WorldWideScience

Sample records for composition soil organic

  1. Repeated application of organic waste affects soil organic matter composition

    DEFF Research Database (Denmark)

    Peltre, Clément; Gregorich, Edward G.; Bruun, Sander

    2017-01-01

    Land application of organic waste is an important alternative to landfilling and incineration because it helps restore soil fertility and has environmental and agronomic benefits. These benefits may be related to the biochemical composition of the waste, which can result in the accumulation...... of different types of carbon compounds in soil. The objective of this study was to identify and characterise changes in soil organic matter (SOM) composition after repeated applications of organic waste. Soil from the CRUCIAL field experiment in Denmark was sampled after 12 years of annual application...... that there was accumulation in soil of different C compounds for the different types of applied organic waste, which appeared to be related to the degree to which microbial activity was stimulated and the type of microbial communities applied with the wastes or associated with the decomposition of applied wastes...

  2. Soil type-depending effect of paddy management: composition and distribution of soil organic matter

    Science.gov (United States)

    Urbanski, Livia; Kölbl, Angelika; Lehndorff, Eva; Houtermans, Miriam; Schad, Peter; Zhang, Gang-Lin; Rahayu Utami, Sri; Kögel-Knabner, Ingrid

    2016-04-01

    Paddy soil management is assumed to promote soil organic matter accumulation and specifically lignin caused by the resistance of the aromatic lignin structure against biodegradation under anaerobic conditions during inundation of paddy fields. The present study investigates the effect of paddy soil management on soil organic matter composition compared to agricultural soils which are not used for rice production (non-paddy soils). A variety of major soil types, were chosen in Indonesia (Java), including Alisol, Andosol and Vertisol sites (humid tropical climate of Java, Indonesia) and in China Alisol sites (humid subtropical climate, Nanjing). This soils are typically used for rice cultivation and represent a large range of soil properties to be expected in Asian paddy fields. All topsoils were analysed for their soil organic matter composition by solid-state 13C nuclear magnetic resonance spectroscopy and lignin-derived phenols by CuO oxidation method. The soil organic matter composition, revealed by solid-state 13C nuclear magnetic resonance, was similar for the above named different parent soil types (non-paddy soils) and was also not affected by the specific paddy soil management. The contribution of lignin-related carbon groups to total SOM was similar in the investigated paddy and non-paddy soils. A significant proportion of the total aromatic carbon in some paddy and non-paddy soils was attributed to the application of charcoal as a common management practise. The extraction of lignin-derived phenols revealed low VSC (vanillyl, syringyl, cinnamyl) values for all investigated soils, being typical for agricultural soils. An inherent accumulation of lignin-derived phenols due to paddy management was not found. Lignin-derived phenols seem to be soil type-dependent, shown by different VSC concentrations between the parent soil types. The specific paddy management only affects the lignin-derived phenols in Andosol-derived paddy soils which are characterized by

  3. Two-dimensional NMR spectroscopy strongly enhances soil organic matter composition analysis

    Science.gov (United States)

    Soucemarianadin, Laure; Erhagen, Björn; Öquist, Mats; Nilsson, Mats; Hedenström, Mattias; Schleucher, Jürgen

    2016-04-01

    Soil organic matter (SOM) is the largest terrestrial carbon pool and strongly affects soil properties. With climate change, understanding SOM processes and turnover and how they could be affected by increasing temperatures becomes critical. This is particularly key for organic soils as they represent a huge carbon pool in very sensitive ecosystems, like boreal ecosystems and peatlands. Nevertheless, characterization of SOM molecular composition, which is essential to elucidate soil carbon processes, is not easily achieved, and further advancements in that area are greatly needed. Solid-state one-dimensional (1D) 13C nuclear magnetic resonance (NMR) spectroscopy is often used to characterize its molecular composition, but only provides data on a few major functional groups, which regroup many different molecular fragments. For instance, in the carbohydrates region, signals of all monosaccharides present in many different polymers overlap. This overlap thwarts attempts to identify molecular moieties, resulting in insufficient information to characterize SOM composition. Here we show that two-dimensional (2D) liquid-state 1H-13C NMR spectra provided much richer data on the composition of boreal plant litter and organic surface soil. The 2D spectra indeed resolved overlaps observed in 1D 13C spectra and displayed signals from hundreds of identifiable molecular groups. For example, in the aromatics region, signals from individual lignin units could be recognized. It was hence possible to follow the fate of specific structural moieties in soils. We observed differences between litter and soil samples, and were able to relate them to the decomposition of identifiable moieties. Sample preparation and data acquisition were both simple and fast. Further, using multivariate data analysis, we aimed at linking the detailed chemical fingerprints of SOM to turnover rates in a soil incubation experiment. With the multivariate models, we were able to identify specific molecular

  4. Contents and composition of organic matter in subsurface soils affected by land use and soil mineralogy

    Science.gov (United States)

    Ellerbrock, Ruth H.; Kaiser, Michael

    2010-05-01

    Land use and mineralogy affect the ability of surface as well as subsurface soils to sequester organic carbon and their contribution to mitigate the greenhouse effect. This study aimed to investigate the long-term impact of land use (i.e., arable and forest) and soil mineralogy on contents and composition of soil organic matter (SOM) from subsurface soils. Seven soils different in mineralogy (Albic and Haplic Luvisol, Colluvic and Haplic Regosol, Haplic and Vertic Cambisol, Haplic Stagnosol) were selected within Germany. Soil samples were taken from forest and adjacent arable sites. First, particulate and water soluble organic matter were separated from the subsurface soil samples. From the remaining solid residues the OM(PY) fractions were separated, analyzed for its OC content (OCPY) and characterized by FTIR spectroscopy. For the arable subsurface soils multiple regression analyses indicate significant positive relationships between the soil organic carbon contents and the contents of i) exchangeable Ca and oxalate soluble Fe, and Alox contents. Further for the neutral arable subsurface soils the contents OCPY weighted by its C=O contents were found to be related to the contents of Ca indicating interactions between OM(PY) and Ca cations. For the forest subsurface soils (pH <5) the OCPY contents were positively related with the contents of Na-pyrophosphate soluble Fe and Al. For the acidic forest subsurface soils such findings indicate interactions between OM(PY) and Fe3+ and Al3+ cations. The effects of land use and soil mineralogy on contents and composition of SOM and OM(PY) will be discussed.

  5. Organic matter composition of soil macropore surfaces under different agricultural management practices

    Science.gov (United States)

    Glæsner, Nadia; Leue, Marin; Magid, Jacob; Gerke, Horst H.

    2016-04-01

    Understanding the heterogeneous nature of soil, i.e. properties and processes occurring specifically at local scales is essential for best managing our soil resources for agricultural production. Examination of intact soil structures in order to obtain an increased understanding of how soil systems operate from small to large scale represents a large gap within soil science research. Dissolved chemicals, nutrients and particles are transported through the disturbed plow layer of agricultural soil, where after flow through the lower soil layers occur by preferential flow via macropores. Rapid movement of water through macropores limit the contact between the preferentially moving water and the surrounding soil matrix, therefore contact and exchange of solutes in the water is largely restricted to the surface area of the macropores. Organomineral complex coated surfaces control sorption and exchange properties of solutes, as well as availability of essential nutrients to plant roots and to the preferentially flowing water. DRIFT (Diffuse Reflectance infrared Fourier Transform) Mapping has been developed to examine composition of organic matter coated macropores. In this study macropore surfaces structures will be determined for organic matter composition using DRIFT from a long-term field experiment on waste application to agricultural soil (CRUCIAL, close to Copenhagen, Denmark). Parcels with 5 treatments; accelerated household waste, accelerated sewage sludge, accelerated cattle manure, NPK and unfertilized, will be examined in order to study whether agricultural management have an impact on the organic matter composition of intact structures.

  6. Peat decomposability in managed organic soils in relation to land use, organic matter composition and temperature

    Directory of Open Access Journals (Sweden)

    C. Bader

    2018-02-01

    Full Text Available Organic soils comprise a large yet fragile carbon (C store in the global C cycle. Drainage, necessary for agriculture and forestry, triggers rapid decomposition of soil organic matter (SOM, typically increasing in the order forest < grassland < cropland. However, there is also large variation in decomposition due to differences in hydrological conditions, climate and specific management. Here we studied the role of SOM composition on peat decomposability in a variety of differently managed drained organic soils. We collected a total of 560 samples from 21 organic cropland, grassland and forest soils in Switzerland, monitored their CO2 emission rates in lab incubation experiments over 6 months at two temperatures (10 and 20 °C and related them to various soil characteristics, including bulk density, pH, soil organic carbon (SOC content and elemental ratios (C / N, H / C and O / C. CO2 release ranged from 6 to 195 mg CO2-C g−1 SOC at 10 °C and from 12 to 423 mg g−1 at 20 °C. This variation occurring under controlled conditions suggests that besides soil water regime, weather and management, SOM composition may be an underestimated factor that determines CO2 fluxes measured in field experiments. However, correlations between the investigated chemical SOM characteristics and CO2 emissions were weak. The latter also did not show a dependence on land-use type, although peat under forest was decomposed the least. High CO2 emissions in some topsoils were probably related to the accrual of labile crop residues. A comparison with published CO2 rates from incubated mineral soils indicated no difference in SOM decomposability between these soil classes, suggesting that accumulation of recent, labile plant materials that presumably account for most of the evolved CO2 is not systematically different between mineral and organic soils. In our data set, temperature sensitivity of decomposition (Q10 on average 2.57

  7. Mapping soil organic carbon content and composition across Australia to assess vulnerability to climate change

    Science.gov (United States)

    Viscarra Rossel, R. A.

    2015-12-01

    We can effectively monitor soil condition—and develop sound policies to offset the emissions of greenhouse gases—only with accurate data from which to define baselines. Currently, estimates of soil organic C for countries or continents are either unavailable or largely uncertain because they are derived from sparse data, with large gaps over many areas of the Earth. Here, we derive spatially explicit estimates, and their uncertainty, of the distribution and stock of organic C content and composition in the soil of Australia. The composition of soil organic C may be characterized by chemical separation or physical fractionation based on either particle size or particle density (Skjemstad et al., 2004; Gregorich et al., 2006; Kelleher&Simpson, 2006; Zimmermann et al., 2007). In Australia, for example, Skjemstad et al. (2004) used physical separation of soil samples into 50-2000 and solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, giving the three OC pools, particulate organic carbon (POC), humic organic carbon (HOC) and resistant organic carbon (ROC; charcoal or char-carbon). We assembled and harmonized data from several sources to produce the most comprehensive set of data on the current stock of organic C in soil of the continent. Using them, we have produced a fine spatial resolution baseline map of organic C, POC, HOC and ROC at the continental scale. In this presentation I will describe how we made the maps and how we use them to assess the vulnerability of soil organic C to for instance climate change.

  8. Controlled experimental soil organic matter modification for study of organic pollutant interactions in soil

    International Nuclear Information System (INIS)

    Ahmed, Ashour A.; Kühn, Oliver; Leinweber, Peter

    2012-01-01

    Interactions of organic pollutants with soil organic matter can be studied by adsorption of the pollutants on well-characterized soil samples with constant mineralogy but different organic matter compositions. Therefore, the objectives of the current study are establishing a set of different, well-characterized soil samples by systematic modifications of their organic matter content and molecular composition and prove these modifications by advanced complementary analytical techniques. Modifications were done by off-line pyrolysis and removal/addition of hot-water extracted organic fraction (HWE) from/to the original soil sample. Both pyrolysis-field ionization mass spectrometry (Py-FIMS) and synchrotron-based C- and N- X-ray absorption near-edge structure spectroscopy (XANES) were applied to investigate the composition of the soil organic matter. These complementary analytical methods in addition to elemental analysis agreed in showing the following order of organic matter contents: pyrolyzed soil < soil residue < original soil < soil + 3 HWE < soil + 6 HWE < HWE. The addition of HWE to the soil sample increases the relative proportions of carbohydrates, N-containing heterocyclic compounds and peptides, and decreases the relative proportions of phenols, lignin monomers and dimers, and lipids. The most abundant organic compound classes in the pyrolyzed sample are aromatics, aliphatic nitriles, aldehydes, five- and six-membered N-containing heterocyclic compounds, and aliphatic carboxylic acids. It can be expected that removal or addition of HWE, that mimic biomass inputs to soil or soil amendments, change the binding capacity for organic pollutants less intensively than heat impact, e.g. from vegetation burning. It will be possible to interpret kinetic data on the pollutants adsorption by these original and modified soil samples on the basis of the bond- and element-specific speciation data through C-XANES and N-XANES and the molecular-level characterization

  9. Impacts of Fertilization Regimes on Arbuscular Mycorrhizal Fungal (AMF) Community Composition Were Correlated with Organic Matter Composition in Maize Rhizosphere Soil.

    Science.gov (United States)

    Zhu, Chen; Ling, Ning; Guo, Junjie; Wang, Min; Guo, Shiwei; Shen, Qirong

    2016-01-01

    The understanding of the response of arbuscular mycorrhizal fungi (AMF) community composition to fertilization is of great significance in sustainable agriculture. However, how fertilization influences AMF diversity and composition is not well-established yet. A field experiment located in northeast China in typical black soil (Chernozem) was conducted and high-throughput sequencing approach was used to investigate the effects of different fertilizations on the variation of AMF community in the rhizosphere soil of maize crop. The results showed that AMF diversity in the maize rhizosphere was significantly altered by different fertilization regimes. As revealed by redundancy analysis, the application of organic manure was the most important factor impacting AMF community composition between samples with and without organic manure, followed by N fertilizer and P fertilizer inputs. Moreover, the organic matter composition in the rhizosphere, determined by GC-MS, was significantly altered by the organic manure amendment. Many of the chemical components displayed significant relationships with the AMF community composition according to the Mantel test, among those, 2-ethylnaphthalene explained the highest percentage (54.2%) of the variation. The relative contents of 2-ethylnaphthalene and 2, 6, 10-trimethyltetradecane had a negative correlation with Glomus relative abundance, while the relative content of 3-methylbiphenyl displayed a positive correlation with Rhizophagus . The co-occurrence patterns in treatments with and without organic manure amendment were analyzed, and more hubs were detected in the network of soils with organic manure amendment. Additionally, three operational taxonomic units (OTUs) belonging to Glomerales were identified as hubs in all treatments, indicating these OTUs likely occupied broad ecological niches and were always active for mediating AMF species interaction in the maize rhizosphere. Taken together, impacts of fertilization regimes on

  10. Impacts of fertilization regimes on arbuscular mycorrhizal fungal (AMF community composition were correlated with organic matter composition in maize rhizosphere soil

    Directory of Open Access Journals (Sweden)

    Chen Zhu

    2016-11-01

    Full Text Available The understanding of the response of arbuscular mycorrhizal fungi (AMF community composition to fertilization is of great significance in sustainable agriculture. However, how fertilization influences AMF diversity and composition is not well established yet. A field experiment located in northeast China in typical black soil (Chernozem was conducted and high-throughput sequencing approach was used to investigate the effects of different fertilizations on the variation of AMF community in the rhizosphere soil of maize crop. The results showed that AMF diversity in the maize rhizosphere was significantly altered by different fertilization regimes. As revealed by redundancy analysis, the application of organic manure was the most important factor impacting AMF community composition between samples with and without organic manure, followed by N fertilizer and P fertilizer inputs. Moreover, the organic matter composition in the rhizosphere, determined by GC-MS, was significantly altered by the organic manure amendment. Many of the chemical components displayed significant relationships with the AMF community composition according to the Mantel test, among those, 2-ethylnaphthalene explained the highest percentage (54.2% of the variation. The relative contents of 2-ethylnaphthalene and 2, 6, 10-trimethyltetradecane had a negative correlation with Glomus relative abundance, while the relative content of 3-methylbiphenyl displayed a positive correlation with Rhizophagus. The co-occurrence patterns in treatments with and without organic manure amendment were analysed, and more hubs were detected in the network of soils with organic manure amendment. Additionally, three OTUs belonging to Glomerales were identified as hubs in all treatments, indicating these OTUs likely occupied broad ecological niches and were always active for mediating AMF species interaction in the maize rhizosphere. Taken together, impacts of fertilization regimes on AMF community

  11. Drivers of lignin composition in boreal forest organic soils across a climate gradient

    Science.gov (United States)

    Myers-Pigg, A.; Kaiser, K.; Benner, R. H.; Ziegler, S. E.

    2017-12-01

    Lignin diagenesis in soils, including the cumulative effects of degradation and leaching, increases with experimental warming, signifying a potentially important change relevant to soil organic matter accumulation and fate. However, decadal to centennial climatic effects including changes in precipitation, litterfall inputs, and understory sources, on lignin composition are poorly constrained. We examined the lignin content and composition, via cupric oxide oxidation (CuO), within the organic layers of podzolic soils under similar balsam fir forests across a latitudinal climate gradient in Atlantic Canada. By exploring variation in lignin by both soil depth and climate region, this study informs on the climate drivers of lignin stability within boreal forest soil. A two-way analysis of variance (ANOVA) revealed significant variations in common signatures of CuO by-products with depth and/or site, indicating source and/or diagenetic controllers. Importantly, none of these signatures, with the exception of p-hydroxyphenols, exhibited a site by depth interaction indicating a similar degree of diagenetic alternation with depth across climates. The site by depth interaction for p-hydroxyphenols is a result of greater moss input in the northernmost site. To better elucidate this climate-induced source variation on our interpretation of lignin diagenesis, a principle component (PCA) model was built using signatures varying by site (pforest soils. A lignin diagenesis PCA model was built using (1) all non-moss related signatures identified in the first PCA model, and (2) scores for additional sites within each region, calculated from modeled lignin composition based on 13C-NMR spectra. The combined results indicate that the lignin diagenetic states among soils is similar, despite the large increase in soil C turnover with climate warming across this transect. Thus our results indicate that shifts in moss contribution, and not increased diagenesis, controls CuO by

  12. Digging a Little Deeper: Microbial Communities, Molecular Composition and Soil Organic Matter Turnover along Tropical Forest Soil Depth Profiles

    Science.gov (United States)

    Pett-Ridge, J.; McFarlane, K. J.; Heckman, K. A.; Reed, S.; Green, E. A.; Nico, P. S.; Tfaily, M. M.; Wood, T. E.; Plante, A. F.

    2016-12-01

    Tropical forest soils store more carbon (C) than any other terrestrial ecosystem and exchange vast amounts of CO2, water, and energy with the atmosphere. Much of this C is leached and stored in deep soil layers where we know little about its fate or the microbial communities that drive deep soil biogeochemistry. Organic matter (OM) in tropical soils appears to be associated with mineral particles, suggesting deep soils may provide greater C stabilization. However, few studies have evaluated sub-surface soils in tropical ecosystems, including estimates of the turnover times of deep soil C, the sensitivity of this C to global environmental change, and the microorganisms involved. We quantified bulk C pools, microbial communities, molecular composition of soil organic matter, and soil radiocarbon turnover times from surface soils to 1.5m depths in multiple soil pits across the Luquillo Experimental Forest, Puerto Rico. Soil C, nitrogen, and root and microbial biomass all declined exponentially with depth; total C concentrations dropped from 5.5% at the surface to communities in surface soils (Acidobacteria and Proteobacteria) versus those below the active rooting zone (Verrucomicrobia and Thaumarchaea). High resolution mass spectrometry (FTICR-MS) analyses suggest a shift in the composition of OM with depth (especially in the water soluble fraction), an increase in oxidation, and decreasing H/C with depth (indicating higher aromaticity). Additionally, surface samples were rich in lignin-like compounds of plant origin that were absent with depth. Soil OM 14C and mean turnover times were variable across replicate horizons, ranging from 3-1500 years at the surface, to 5000-40,000 years at depth. In comparison to temperate deciduous forests, these 14C values reflect far older soil C. Particulate organic matter (free light fraction), with a relatively modern 14C was found in low but measureable concentration in even the deepest soil horizons. Our results indicate these

  13. How soil organic matter composition controls hexachlorobenzene-soil-interactions: adsorption isotherms and quantum chemical modeling.

    Science.gov (United States)

    Ahmed, Ashour A; Kühn, Oliver; Aziz, Saadullah G; Hilal, Rifaat H; Leinweber, Peter

    2014-04-01

    Hazardous persistent organic pollutants (POPs) interact in soil with the soil organic matter (SOM) but this interaction is insufficiently understood at the molecular level. We investigated the adsorption of hexachlorobenzene (HCB) on soil samples with systematically modified SOM. These samples included the original soil, the soil modified by adding a hot water extract (HWE) fraction (soil+3 HWE and soil+6 HWE), and the pyrolyzed soil. The SOM contents increased in the order pyrolyzed soilsoilsoil+3 HWEsoil+6 HWE. For the latter three samples this order was also valid for the HCB adsorption. The pyrolyzed soil adsorbed more HCB than the other samples at low initial concentrations, but at higher concentrations the HCB adsorption became weaker than in the samples with HWE addition. This adsorption combined with the differences in the chemical composition between the soil samples suggested that alkylated aromatic, phenol, and lignin monomer compounds contributed most to the HCB adsorption. To obtain a molecular level understanding, a test set has been developed on the basis of elemental analysis which comprises 32 representative soil constituents. The calculated binding energy for HCB with each representative system shows that HCB binds to SOM stronger than to soil minerals. For SOM, HCB binds to alkylated aromatic, phenols, lignin monomers, and hydrophobic aliphatic compounds stronger than to polar aliphatic compounds confirming the above adsorption isotherms. Moreover, quantitative structure-activity relationship (QSAR) of the binding energy with independent physical properties of the test set systems for the first time indicated that the polarizability, the partial charge on the carbon atoms, and the molar volume are the most important properties controlling HCB-SOM interactions. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Alteration of Chemical Composition of Soil-leached Dissolved Organic Matter under Cryogenic Cycles

    Science.gov (United States)

    Zhang, X.; Bianchi, T. S.; Schuur, E.

    2016-02-01

    Arctic permafrost thawing has drawn great attention because of the large amount of organic carbon (OC) storage in Arctic soils that are susceptible to increasing global temperatures. Due to microbial activities, some of the OC pool is converted in part to greenhouse gases, like CH4 and CO2 gas, which can result in a positive feedback on global warming. In Artic soils, a portion of OC can be mobilized by precipitation, drainage, and groundwater circulation which can in some cases be transported to rivers and eventually the coastal margins. To determine some of the mechanisms associated with the mobilization of OC from soils to aquatic ecosystems, we conducted a series of laboratory soil leaching experiments. Surface soil samples collected from Healy, Alaska were eluted with artificial rain at a constant rate. Leachates were collected over time and analyzed for dissolved organic carbon (DOC) concentrations. Concentrations began from 387-705 mg/L and then dropped to asymptote states to 25-219 mg/L. High-resolution spectroscopy was used to characterize colored dissolved organic matter (CDOM) and CDOM fluorescence intensity also dropped with time. Fluorescence maximum intensity (Fmax) for peak C ranged from 0.7-4.2 RU, with Exmax/Emmax = 310/450 nm. Fmax for peak T ranged from 0.5-3.2 RU, with Exmax/Emmax = 275/325 nm. Peak C: peak T values indicated preferential leaching of humic-like components over protein-like components. After reaching asymptotic levels, samples were stored frozen and then thawed to study the cryogenic impact on OC composition. CDOM intensity and DOC concentration increased after the freeze-thaw cycle. It was likely that cryogenic processes promoted the breakdown of OC and the releases of more DOC from soils. PARAFAC of CDOM excitation and emission matrices (EEMs) will be used to analyze CDOM composition of the soil leachates.

  15. Assessing the Impact of Land Management on Organic Matter Composition in Peat Soils

    Science.gov (United States)

    Savage, A.; Holden, J.; Wainwright, J.

    2010-05-01

    Peatlands are seen as important stores of terrestrial carbon, accounting for up to one-third of global soil carbon stocks. In some cases peatlands are shown to be emitters of carbon, in other cases carbon sinks depending on the site conditions and nature of degradation. However, carbon budget calculations carried out to date have a number of uncertainties associated with them and the composition of the carbon is generally not considered when determining carbon budgets. Carbon cycling in peat is driven by four key factors (Laiho, 2006):, environmental conditions (e.g. temperature, water table level), substrate quality (e.g. how recalcitrant the peat is), nutrients (e.g. nitrogen required to synthesis the carbon stocks) and microbial community (e.g. are the microbes present able to utilise the available substrate). Land management is also recognised as an additional driver, but the impacts of many types of management are poorly understood. Among the four drivers listed by Laiho (2006) substrate quality is seen as the most significant. To date, little work has been carried out to characterise the quality of organic matter in peat soils; rather crude estimates have been made as to the quantity of carbon that is stored in peatlands, yet without understanding the composition of the peat, limitations are imposed on calculations of rates of carbon loss from peatlands. This work seeks to examine how variations in the chemical composition of organic matter in peat varies with land use. The method published by Wieder and Starr (1998) was followed to determine eight fractions: soluble fats and waxes, hot water soluble, hollocellulose, cellulose, soluble phenolics, acid insoluble carbohydrates, water soluble carbohydrates and lignin. Samples were taken from burnt, grazed, drained, afforested and undisturbed sites at the Moor House UNESCO Biosphere Reserve in Northern England. The method was used to identify if differences were present in the recalcitrance of the peat and linked

  16. DOM composition and transformation in boreal forest soils: The effects of temperature and organic-horizon decomposition state

    Science.gov (United States)

    O’Donnell, Jonathan A.; Aiken, George R.; Butler, Kenna D.; Guillemette, Francois; Podgorski, David C.; Spencer, Robert G. M.

    2016-01-01

    The boreal region stores large amounts of organic carbon (C) in organic-soil horizons, which are vulnerable to destabilization via warming and disturbance. Decomposition of soil organic matter (SOM) contributes to the production and turnover of dissolved organic matter (DOM). While temperature is a primary control on rates of SOM and DOM cycling, little is known about temperature effects on DOM composition in soil leachate. Here we conducted a 30 day incubation to examine the effects of temperature (20 versus 5°C) and SOM decomposition state (moss versus fibric versus amorphous horizons) on DOM composition in organic soils of interior Alaska. We characterized DOM using bulk dissolved organic C (DOC) concentration, chemical fractionation, optical properties, and ultrahigh-resolution mass spectrometry. We observed an increase in DOC concentration and DOM aromaticity in the 20°C treatment compared to the 5°C treatment. Leachate from fibric horizons had higher DOC concentration than shallow moss or deep amorphous horizons. We also observed chemical shifts in DOM leachate over time, including increases in hydrophobic organic acids, polyphenols, and condensed aromatics and decreases in low-molecular weight hydrophilic compounds and aliphatics. We compared ultrahigh-resolution mass spectrometry and optical data and observed strong correlations between polyphenols, condensed aromatics, SUVA254, and humic-like fluorescence intensities. These findings suggest that biolabile DOM was preferentially mineralized, and the magnitude of this transformation was determined by kinetics (i.e., temperature) and substrate quality (i.e., soil horizon). With future warming, our findings indicate that organic soils may release higher concentrations of aromatic DOM to aquatic ecosystems.

  17. [Distribution characteristics of soil organic carbon and its composition in Suaeda salsa wetland in the Yellow River delta].

    Science.gov (United States)

    Dong, Hong-Fang; Yu, Jun-Bao; Guan, Bo

    2013-01-01

    Applying the method of physical fractionation, distribution characteristics of soil organic carbon and its composition in Suaeda salsa wetland in the Yellow River delta were studied. The results showed that the heavy fraction organic carbon was the dominant component of soil organic carbon in the studied region. There was a significantly positive relationship between the content of heavy fraction organic carbon, particulate organic carbon and total soil organic carbon. The ranges of soil light fraction organic carbon ratio and content were 0.008% - 0.15% and 0.10-0.40 g x kg(-1), respectively, and the range of particulate organic carbon ratio was 8.83% - 30.58%, indicating that the non-protection component of soil organic carbon was low and the carbon pool was relatively stable in Suaeda salsa wetland of the Yellow River delta.

  18. Organic matter composition and stabilization in a polygonal tundra soil of the Lena Delta

    Directory of Open Access Journals (Sweden)

    S. Höfle

    2013-05-01

    Full Text Available This study investigated soil organic matter (OM composition of differently stabilized soil OM fractions in the active layer of a polygonal tundra soil in the Lena Delta, Russia, by applying density and particle size fractionation combined with qualitative OM analysis using solid state 13C nuclear magnetic resonance spectroscopy, and lipid analysis combined with 14C analysis. Bulk soil OM was mainly composed of plant-derived, little-decomposed material with surprisingly high and strongly increasing apparent 14C ages with active layer depth suggesting slow microbial OM transformation in cold climate. Most soil organic carbon was stored in clay and fine-silt fractions (n-alkane and n-fatty acid compounds and low alkyl/O-alkyl C ratios. Organo-mineral associations, which are suggested to be a key mechanism of OM stabilization in temperate soils, seem to be less important in the active layer as the mainly plant-derived clay- and fine-silt-sized OM was surprisingly "young", with 14C contents similar to the bulk soil values. Furthermore, these fractions contained less organic carbon compared to density fractionated OM occluded in soil aggregates – a further important OM stabilization mechanism in temperate soils restricting accessibility of microorganisms. This process seems to be important at greater active layer depth where particulate OM, occluded in soil aggregates, was "older" than free particulate OM.

  19. A molecular investigation of soil organic carbon composition across a subalpine catchment

    Science.gov (United States)

    Hsu, Hsiao-Tieh; Lawrence, Corey R.; Winnick, Matthew J.; Bargar, John R.; Maher, Katharine

    2018-01-01

    The dynamics of soil organic carbon (SOC) storage and turnover are a critical component of the global carbon cycle. Mechanistic models seeking to represent these complex dynamics require detailed SOC compositions, which are currently difficult to characterize quantitatively. Here, we address this challenge by using a novel approach that combines Fourier transform infrared spectroscopy (FT-IR) and bulk carbon X-ray absorption spectroscopy (XAS) to determine the abundance of SOC functional groups, using elemental analysis (EA) to constrain the total amount of SOC. We used this SOC functional group abundance (SOC-fga) method to compare variability in SOC compositions as a function of depth across a subalpine watershed (East River, Colorado, USA) and found a large degree of variability in SOC functional group abundances between sites at different elevations. Soils at a lower elevation are predominantly composed of polysaccharides, while soils at a higher elevation have more substantial portions of carbonyl, phenolic, or aromatic carbon. We discuss the potential drivers of differences in SOC composition between these sites, including vegetation inputs, internal processing and losses, and elevation-driven environmental factors. Although numerical models would facilitate the understanding and evaluation of the observed SOC distributions, quantitative and meaningful measurements of SOC molecular compositions are required to guide such models. Comparison among commonly used characterization techniques on shared reference materials is a critical next step for advancing our understanding of the complex processes controlling SOC compositions.

  20. The isotopic composition of soil organic carbon on a north - south transect in western Canada

    Czech Academy of Sciences Publication Activity Database

    Bird, M.; Šantrůčková, Hana; Lloyd, J.; Lawson, E.

    2002-01-01

    Roč. 53, - (2002), s. 393-403 ISSN 1351-0754 Institutional research plan: CEZ:AV0Z6066911 Keywords : isotopic composition * soil organic carbon * western Canada Subject RIV: EH - Ecology, Behaviour Impact factor: 1.452, year: 2002

  1. Organic components and plutonium and americium state in soils and soil solutions

    International Nuclear Information System (INIS)

    Sokolik, G.A.; Ovsyannikova, S.V.; Kimlenko, I.M.

    2002-01-01

    The fraction composition of humus substances of different type soils and soil solutions have been studied. A distribution of Pu 239, 240 and Am 241 between humus substances fractions of different dispersity and mobility in soil-vegetation cover has been established. It was shown that humus of organic soils fixes plutonium and americium in soil medium in greater extent than humus of mineral soils. That leads to lower migration ability of radionuclides in organic soils. The lower ability of americium to form difficultly soluble organic and organic-mineral complexes and predomination of its anion complexes in soil solutions may be a reason of higher mobility and biological availability of americium in comparison to plutonium during soil-plant transfer (authors)

  2. The influence of tree species composition on the storage and mobility of semivolatile organic compounds in forest soils

    Energy Technology Data Exchange (ETDEWEB)

    Komprdová, Klára, E-mail: komprdova@recetox.muni.cz [RECETOX (Research Centre for Toxic Compounds in the Environment), Kamenice 753/5, CZ-625 00 Brno (Czech Republic); Komprda, Jiří [RECETOX (Research Centre for Toxic Compounds in the Environment), Kamenice 753/5, CZ-625 00 Brno (Czech Republic); Menšík, Ladislav [Mendel University in Brno, Faculty of Forestry and Wood Technology, Zemědělská 3, Brno 613 00 (Czech Republic); Vaňková, Lenka [RECETOX (Research Centre for Toxic Compounds in the Environment), Kamenice 753/5, CZ-625 00 Brno (Czech Republic); Kulhavý, Jiří [Mendel University in Brno, Faculty of Forestry and Wood Technology, Zemědělská 3, Brno 613 00 (Czech Republic); Nizzetto, Luca [RECETOX (Research Centre for Toxic Compounds in the Environment), Kamenice 753/5, CZ-625 00 Brno (Czech Republic); Norwegian Institute for Water Research, Gaustadalleen 21, NO-0349 Oslo (Norway)

    2016-05-15

    Soil contamination with PCBs and PAHs in adjacent forest plots, characterized by a distinct composition in tree species (spruce only, mixed and beech only), was analyzed to investigate the influence of ecosystem type on contaminant mobility in soil under very similar climate and exposure conditions. Physical-chemical properties and contaminant concentrations in litter (L), organic (F, H) and mineral (A, B) soil horizons were analyzed. Contaminant distribution in the soil core varied both in relation to forest type and contaminant group/properties. Contaminant mobility in soil was assessed by examining the ratios of total organic carbon (TOC)-standardized concentrations across soil horizons (Enrichment factors, EF{sub TOC}) and the relationship between EF{sub TOC} and the octanol-water equilibrium partitioning coefficient (K{sub OW}). Contaminant distribution appeared to be highly unsteady, with pedogenic/biogeochemical drivers controlling contaminant mobility in organic layers and leaching controlling accumulation in mineral layers. Lighter PCBs displayed higher mobility in all forest types primarily controlled by leaching and, to a minor extent, diffusion. Pedogenic processes controlling the formation of soil horizons were found to be crucial drivers of PAHs and heavier PCBs distribution. All contaminants appeared to be more mobile in the soil of the broadleaved plot, followed by mixed canopy and spruce forest. Increasing proportion of deciduous broadleaf species in the forest can thus lead to faster degradation or the faster leaching of PAHs and PCBs. The composition of humic substances was found to be a better descriptor of contaminant concentration than TOC. - Highlights: • Tree species composition influences vertical distribution of PCBs and PAHs in soils. • PCBs and PAHs were more mobile in the soil of the broadleaved plot. • Low molecular weight PCBs displayed higher mobility in all forest types. • Humic substances were important descriptors of

  3. The influence of tree species composition on the storage and mobility of semivolatile organic compounds in forest soils

    International Nuclear Information System (INIS)

    Komprdová, Klára; Komprda, Jiří; Menšík, Ladislav; Vaňková, Lenka; Kulhavý, Jiří; Nizzetto, Luca

    2016-01-01

    Soil contamination with PCBs and PAHs in adjacent forest plots, characterized by a distinct composition in tree species (spruce only, mixed and beech only), was analyzed to investigate the influence of ecosystem type on contaminant mobility in soil under very similar climate and exposure conditions. Physical-chemical properties and contaminant concentrations in litter (L), organic (F, H) and mineral (A, B) soil horizons were analyzed. Contaminant distribution in the soil core varied both in relation to forest type and contaminant group/properties. Contaminant mobility in soil was assessed by examining the ratios of total organic carbon (TOC)-standardized concentrations across soil horizons (Enrichment factors, EF_T_O_C) and the relationship between EF_T_O_C and the octanol-water equilibrium partitioning coefficient (K_O_W). Contaminant distribution appeared to be highly unsteady, with pedogenic/biogeochemical drivers controlling contaminant mobility in organic layers and leaching controlling accumulation in mineral layers. Lighter PCBs displayed higher mobility in all forest types primarily controlled by leaching and, to a minor extent, diffusion. Pedogenic processes controlling the formation of soil horizons were found to be crucial drivers of PAHs and heavier PCBs distribution. All contaminants appeared to be more mobile in the soil of the broadleaved plot, followed by mixed canopy and spruce forest. Increasing proportion of deciduous broadleaf species in the forest can thus lead to faster degradation or the faster leaching of PAHs and PCBs. The composition of humic substances was found to be a better descriptor of contaminant concentration than TOC. - Highlights: • Tree species composition influences vertical distribution of PCBs and PAHs in soils. • PCBs and PAHs were more mobile in the soil of the broadleaved plot. • Low molecular weight PCBs displayed higher mobility in all forest types. • Humic substances were important descriptors of contaminant

  4. Ofloxacin sorption in soils after long-term tillage: The contribution of organic and mineral compositions

    International Nuclear Information System (INIS)

    Zhou, Dandan; Chen, Bingfa; Wu, Min; Liang, Ni; Zhang, Di; Li, Hao; Pan, Bo

    2014-01-01

    Intensive human activities in agricultural areas resulted in significant alteration of soil properties, which consequently change their interactions with various contaminants. This process needs to be incorporated in contaminant behavior prediction and their risk assessment. However, the relevant study is missing. This work was designed to examine the change of soil properties and ofloxacin (OFL) sorption after tillage. Soil samples were collected in Yuanyang, Mengzi, and Dianchi areas with different agricultural activities. Although the mineral compositions of soils from Yuanyang and Dianchi differed greatly, these compositions are similar after tillage, especially for paddy soils. Soil pH decreased generally after OFL sorption, suggesting that ion exchange of OFL with protons in soil organic matter (SOM) was important for OFL sorption. However, a positive relationship between SOM and OFL sorption was not observed. On the contrary, increased SOM decreased OFL sorption when soils from the same geological location were compared. Generally speaking, tillage activities or dense vegetations greatly decreased OFL sorption. The higher OFL sorption in B horizon than A horizon suggested limited leaching of OFL through soil columns. The summed sorption calculated based on the sorption of individual soil components and their percentages in soils was higher than the intact soil. This phenomenon may be understood from the interactions between soil components, such as the coating of SOM on mineral particles. This study emphasizes that soil should be treat as a dynamic environmental matrix when assessing antibiotic behaviors and risks, especially in the area with intense human activities. - Highlights: • Mineral compositions tend to be similar after tillage. • Increased SOM decreases OFL sorption for soils from the same geological location. • Tillage activities or dense vegetations greatly decrease OFL sorption. • The summed sorption of individual soil components is

  5. Compositional changes of soil organic matter with cropping time were more profound in subsoils and distinct between Phaeozem and Chernozem in Northeast China

    Science.gov (United States)

    Soil organic matter (SOM) contributes to soil processes and is found both in shallow and deep soil layers. Its activity can be affected by its chemical composition, yet knowledge is incomplete of how land use alters the structural composition of SOM throughout the profiles of different soil types. T...

  6. Radiocarbon and stable carbon isotope compositions of chemically fractionated soil organic matter in a temperate-zone forest

    International Nuclear Information System (INIS)

    Koarashi, Jun; Iida, Takao; Asano, Tomohiro

    2005-01-01

    To better understand the role of soil organic matter in terrestrial carbon cycle, carbon isotope compositions in soil samples from a temperate-zone forest were measured for bulk, acid-insoluble and base-insoluble organic matter fractions separated by a chemical fractionation method. The measurements also made it possible to estimate indirectly radiocarbon ( 14 C) abundances of acid- and base-soluble organic matter fractions, through a mass balance of carbon among the fractions. The depth profiles of 14 C abundances showed that (1) bomb-derived 14 C has penetrated the first 16 cm mineral soil at least; (2) Δ 14 C values of acid-soluble organic matter fraction are considerably higher than those of other fractions; and (3) a significant amount of the bomb-derived 14 C has been preserved as the base-soluble organic matter around litter-mineral soil boundary. In contrast, no or little bomb-derived 14 C was observed for the base-insoluble fraction in all sampling depths, indicating that this recalcitrant fraction, accounting for approximately 15% of total carbon in this temperate-zone forest soil, plays a role as a long-term sink in the carbon cycle. These results suggest that bulk soil organic matter cannot provide a representative indicator as a source or a sink of carbon in soil, particularly on annual to decadal timescales

  7. Electrical Conductivity and Chemical Composition of Soil Solution: Comparison of Solution Samplers in Tropical Soils

    Directory of Open Access Journals (Sweden)

    Davi Lopes do Carmo

    2016-01-01

    Full Text Available ABSTRACT Soil solution samplers may have the same working principle, but they differ in relation to chemical and physical characteristics, cost and handling, and these aspects exert influence on the chemical composition of the soil solution obtained. This study was carried out to evaluate, over time, the chemical composition of solutions extracted by Suolo Acqua, with the hydrophilic membrane (HM as a standard, using soils with contrasting characteristics, and to determine the relationship between electrical conductivity (EC and concentration of ions and pH of soil solution samples. This study was carried out under laboratory conditions, using three soils samples with different clay and organic matter (OM contents. Soil solution contents of F−, Cl−, NO−3, Br−, SO42−, Na+, NH4+, K+, Mg2+, Ca2+, were analyzed, as well as inorganic, organic, and total C contents, pH, and EC, in four successive sampling times. Soil solution chemical composition extracted by the Suolo Acqua sampler is similar to that collected by the HM, but the Suolo Acqua extracted more Na+ and soluble organic C than the HM solution. Solution EC, cation and anion concentrations, and soluble C levels are higher in the soil with greater clay and OM contents (Latossolo and Cambissolo in this case. Soil solution composition varied over time, with considerable changes in pH, EC, and nutrient concentrations, especially associated with soil OM. Thus, single and isolated sampling of the soil solution must be avoided, otherwise composition of the soil solution may not be correctly evaluated. Soil solution EC was regulated by pH, as well as the sum of cation and anion concentrations, and the C contents determined in the soil liquid phase.

  8. Effects of organic matter fraction and compositional changes on distribution of cadmium and zinc in long-term polluted paddy soils

    International Nuclear Information System (INIS)

    Zhou, Tong; Wu, Longhua; Luo, Yongming; Christie, Peter

    2018-01-01

    Soil particulate organic matter (POM) has rapid turnover and metal enrichment, but the interactions between organic matter (OM) and metals have not been well studied. The present study aimed to investigate changes in the OM concentration and composition of the POM fraction and their corresponding effects on metal distribution and extractability in long-term polluted paddy soils. Soil 2000–53 μm POM size fractions had higher contents of C–H and C=O bonds, C–H/C=O ratios and concentrations of fulvic acid (FA), humic acid (HA), cadmium (Cd) and zinc (Zn) than the bulk soils. Cadmium and Zn stocks in soil POM fractions were 24.5–27.9% and 7.12–16.7%, respectively, and were more readily EDTA-extractable. Compared with the control soil, the 2000–250 μm POM size fractions had higher organic carbon concentrations and C/N ratios in the polluted soils. However, there were no significant differences in the contents in C–H and C=O bonds or C–H/C=O ratios of POM fractions among the control, slightly and highly polluted soils. In accordance with the lower contents of C=O bonds and FA and HA concentrations, the Cd and Zn concentrations in 250–53 μm POM size fractions were lower than those in 2000–250 μm POM size fractions. Enrichment of Cd in POM fractions increased with increasing soil pollution level. These results support the view that changes in the OM concentration and the size and composition of POM fractions play a key role in determining the distribution of Cd and Zn in paddy soils. - Highlights: • The OC and FA contents and C/N in POM (2000–250 μm) increased in polluted soil. • Enrichment of Cd and Zn decreased with decreasing POM size. • No significant change in content of C=O group in POM was observed in polluted soil. • Changes in the size and composition of soil POM affected the Cd and Zn distribution. - Interactions between soil organic matter and metals.

  9. Influence of organic components on plutonium and americium speciation in soils and soil solutions

    International Nuclear Information System (INIS)

    Sokolik, G.A.; Ovsyannikova, S.V.; Kimlenko, I.M.

    2003-01-01

    Group composition of humic substances of organic and mineral soils sampled in the 30-km zone of the Chernobyl accident was analyzed for studying influence of organic components on migration properties of plutonium and americium in soils and soil solutions by the method of gel-chromatography and chemical fractionation. It was ascertained that humus of organic soils binds plutonium and americium stronger than humus of mineral soils. Elevated mobility of americium compared to plutonium one stems from lower ability of the latter to from hard to solve organic and organomineral complexes, as well as from its ability to form anionic complexes in soil solutions [ru

  10. Characterization of Soil Organic Matter from African Dark Earth (AfDE) Soils

    Science.gov (United States)

    Plante, A. F.; Fujiu, M.; Ohno, T.; Solomon, D.; Lehmann, J.; Fraser, J. A.; Leach, M.; Fairhead, J.

    2014-12-01

    Anthropogenic Dark Earths are soils generated through long-term human inputs of organic and pyrogenic materials. These soils were originally discovered in the Amazon, and have since been found in Australia and in this case in Africa. While tropical soils are typically characterized by low soil organic matter (SOM) concentrations, African Dark Earths (AfDE) are black, highly fertile and carbon-rich soils formed through an extant but ancient soil management system. The objective of this study was to characterize the organic matter accumulated in AfDE and contrast it with non-AfDE soils. Characterization of bulk soil organic matter of several (n=11) AfDE and non-AfDE pairs of surface (0-15 cm) soils using thermal analysis techniques (TG-DSC-EGA) resulted in substantial differences in SOM composition and the presence of pyrogenic C. Such pyrogenic organic matter is generally considered recalcitrant, but the fertility gains in AfDE are generated by labile, more rapidly cycling pools of SOM. As a result, we characterized hot water- and pyrophosphate-extractable pools of SOM using fluorescence (EEM/PARAFAC) and high resolution mass spectrometry (FT-ICR-MS). EEM/PARAFAC data suggests that AfDE samples had a greater fraction of their DOM that was more humic-like than the paired non-AfDE samples. Similarly, FT-ICR-MS analyses of extracts suggest that differences among the sites analyzed were larger than between the paired AfDE and non-AfDE extracts. Overall, in spite of substantial differences in the composition of bulk SOM, the extractable fractions appear to be relatively similar between the AfDE and non-AfDE soils.

  11. Structural composition of organic matter in particle-size fractions of soils along a climo-biosequence in the main range of Peninsular Malaysia

    Science.gov (United States)

    Jafarzadeh-Haghighi, Amir Hossein; Shamshuddin, Jusop; Hamdan, Jol; Zainuddin, Norhazlin

    2016-09-01

    Information on structural composition of organic matter (OM) in particle-size fractions of soils along a climo-biosequence is sparse. The objective of this study was to examine structural composition and morphological characteristics of OM in particle-size fractions of soils along a climo-biosequence in order to better understand the factors and processes affecting structural composition of soil organic matter. To explore changes in structural composition of OM in soils with different pedogenesis, the A-horizon was considered for further analyses including particle-size fractionation, solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy (SEM). Due to the increase in the thickness of organic layer with increasing elevation, the A-horizon was situated at greater depth in soils of higher elevation. The relationship between relative abundances of carbon (C) structures and particle-size fractions was examined using principal component analysis (PCA). It was found that alkyl C (20.1-73.4%) and O-alkyl C (16.8-67.7%) dominated particle-size fractions. The proportion of alkyl C increased with increasing elevation, while O-alkyl C showed an opposite trend. Results of PCA confirmed this finding and showed the relative enrichment of alkyl C in soils of higher elevation. Increase in the proportion of alkyl C in 250-2000 μm fraction is linked to selective preservation of aliphatic compounds derived from root litter. SEM results showed an increase in root contribution to the 250-2000 μm fraction with increasing elevation. For the changes in structural composition of OM in particle-size fractions of soils along the studied climo-biosequence are attributed to site-specific differences in pedogenesis as a function of climate and vegetation.

  12. Effect of variable soil texture, metal saturation of soil organic matter (SOM) and tree species composition on spatial distribution of SOM in forest soils in Poland.

    Science.gov (United States)

    Gruba, Piotr; Socha, Jarosław; Błońska, Ewa; Lasota, Jarosław

    2015-07-15

    In this study we investigated the effect of fine (ϕclay (FF) content in soils, site moisture, metal (Al and Fe) of soil organic matter (SOM) and forest species composition on the spatial distribution of carbon (C) pools in forest soils at the landscape scale. We established 275 plots in regular 200×200m grid in a forested area of 14.4km(2). Fieldwork included soil sampling of the organic horizon, mineral topsoil and subsoil down to 40cm deep. We analysed the vertical and horizontal distribution of soil organic carbon (SOC) stocks, as well as the quantity of physically separated fractions including the free light (fLF), occluded light (oLF) and mineral associated fractions (MAF) in the mineral topsoil (A, AE) horizons. Distribution of C in soils was predominantly affected by the variation in the FF content. In soils richer in the FF more SOC was accumulated in mineral horizons and less in the organic horizons. Accumulation of SOC in mineral soil was also positively affected by the degree of saturation of SOM with Al and Fe. The increasing share of beech influenced the distribution of C stock in soil profiles by reducing the depth of O horizon and increasing C stored in mineral soil. The content of FF was positively correlated with the content of C in MAF and fLF fractions. The content of oLF and MAF fractions was also positively influenced by a higher degree of metal saturation, particularly Al. Our results confirmed that Al plays an important role in the stabilization of SOM inside aggregates (CoLF) and as in CMAF fractions. We also found a significant, positive effect of beech on the CfLF and fir on the CoLF content. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Application of DRIFTS, 13 C NMR, and py-MBMS to Characterize the Effects of Soil Science Oxidation Assays on Soil Organic Matter Composition in a Mollic Xerofluvent

    Energy Technology Data Exchange (ETDEWEB)

    Margenot, Andrew J.; Calderón, Francisco J.; Magrini, Kimberly A.; Evans, Robert J.

    2016-12-20

    Chemical oxidations are routinely employed in soil science to study soil organic matter (SOM), and their interpretation could be improved by characterizing oxidation effects on SOM composition with spectroscopy. We investigated the effects of routinely employed oxidants on SOM composition in a Mollic Xerofluvent representative of intensively managed agricultural soils in the California Central Valley. Soil samples were subjected to oxidation by potassium permanganate (KMnO4), sodium hypochlorite (NaOCl), and hydrogen peroxide (H2O2). Additionally, non-oxidized and oxidized soils were treated with hydrofluoric acid (HF) to evaluate reduction of the mineral component to improve spectroscopy of oxidation effects. Oxidized non-HF and HF-treated soils were characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), 13C cross polarization magic angle spinning (CP-MAS) nuclear magnetic resonance (NMR) spectroscopy, and pyrolysis molecular beam mass spectrometry (py-MBMS), and for particle size distribution (PSD) using laser diffractometry (LD). Across the range of soil organic carbon (OC) removed by oxidations (14-72%), aliphatic C-H stretch at 3000-2800 cm-1 (DRIFTS) decreased with OC removal, and this trend was enhanced by HF treatment due to significant demineralization in this soil (70%). Analysis by NMR spectroscopy was feasible only after HF treatment, and did not reveal trends between OC removal and C functional groups. Pyrolysis-MBMS did not detect differences among oxidations, even after HF treatment of soils. Hydrofluoric acid entailed OC loss (13-39%), and for H2O2 oxidized soils increased C:N and substantially decreased mean particle size. This study demonstrates the feasibility of using HF to improve characterizations of SOM composition following oxidations as practiced in soil science, in particular for DRIFTS. Since OC removal by oxidants, mineral removal by HF, and the interaction of oxidants and HF observed for this soil may

  14. Soil organic matter composition from correlated thermal analysis and nuclear magnetic resonance data in Australian national inventory of agricultural soils

    Science.gov (United States)

    Moore, T. S.; Sanderman, J.; Baldock, J.; Plante, A. F.

    2016-12-01

    National-scale inventories typically include soil organic carbon (SOC) content, but not chemical composition or biogeochemical stability. Australia's Soil Carbon Research Programme (SCaRP) represents a national inventory of SOC content and composition in agricultural systems. The program used physical fractionation followed by 13C nuclear magnetic resonance (NMR) spectroscopy. While these techniques are highly effective, they are typically too expensive and time consuming for use in large-scale SOC monitoring. We seek to understand if analytical thermal analysis is a viable alternative. Coupled differential scanning calorimetry (DSC) and evolved gas analysis (CO2- and H2O-EGA) yields valuable data on SOC composition and stability via ramped combustion. The technique requires little training to use, and does not require fractionation or other sample pre-treatment. We analyzed 300 agricultural samples collected by SCaRP, divided into four fractions: whole soil, coarse particulates (POM), untreated mineral associated (HUM), and hydrofluoric acid (HF)-treated HUM. All samples were analyzed by DSC-EGA, but only the POM and HF-HUM fractions were analyzed by NMR. Multivariate statistical analyses were used to explore natural clustering in SOC composition and stability based on DSC-EGA data. A partial least-squares regression (PLSR) model was used to explore correlations among the NMR and DSC-EGA data. Correlations demonstrated regions of combustion attributable to specific functional groups, which may relate to SOC stability. We are increasingly challenged with developing an efficient technique to assess SOC composition and stability at large spatial and temporal scales. Correlations between NMR and DSC-EGA may demonstrate the viability of using thermal analysis in lieu of more demanding methods in future large-scale surveys, and may provide data that goes beyond chemical composition to better approach quantification of biogeochemical stability.

  15. Spectral estimation of soil properties in siberian tundra soils and relations with plant species composition

    DEFF Research Database (Denmark)

    Bartholomeus, Harm; Schaepman-Strub, Gabriela; Blok, Daan

    2012-01-01

    yields a good prediction model for K and a moderate model for pH. Using these models, soil properties are determined for a larger number of samples, and soil properties are related to plant species composition. This analysis shows that variation of soil properties is large within vegetation classes......Predicted global warming will be most pronounced in the Arctic and will severely affect permafrost environments. Due to its large spatial extent and large stocks of soil organic carbon, changes to organic matter decomposition rates and associated carbon fluxes in Arctic permafrost soils...

  16. Soil carbon dynamics inferred from carbon isotope compositions of soil organic matter and soil respiration

    International Nuclear Information System (INIS)

    Koarashi, Jun; Asano, Tomohiro; Iida, Takao; Moriizumi, Jun

    2004-01-01

    To better understand 14 C cycling in terrestrial ecosystems, 14 C abundances were evaluated for fractionated soil organic matter (SOM) and soil respiration in an urban forest. In 2001 soil profile, Δ 14 C values of litter and bulk SOM increased rapidly from litter surface (62.7 per mille) to uppermost mineral soil layer (244.9 per mille), and then decreased sharply to 6 cm depth of mineral soil (125.0 per mille). Carbon enriched in 14 C by atmospheric nuclear weapons testing had penetrated to at least 16 cm depth of mineral soil. The average Δ 14 C in atmospheric CO 2 was 58.8 per mille in August 2001, suggesting recent carbon input to the topmost litter layer. Although a similar depth distribution was observed for Δ 14 C values of residual SOM after acid hydrolysis, the Δ 14 C values were slightly lower than those in bulk SOM. This indicates input of 'bomb' C into this organic fraction and higher 14 C abundance in acid-soluble SOM. The most of CO 2 may be derived from the microbial decomposition of the acid-soluble, or labile, SOM. Therefore, the labile SOM may become most influential pool for soil carbon cycling. In contrast, carbon in base-insoluble SOM remained considerably low in 14 C abundance at all depths, suggesting no or little incorporation of 'bomb' C to this fraction. Values of Δ 14 C in soil respiration ranged from 91.9 to 146.4 per mille in August 2001, showing a significant contribution from decomposition of SOM fixed over past 2-40 years. These results indicate that the use of bulk SOM as a representative of soil carbon pool would lead to severe misunderstand of the soil C dynamics on decadal and shorter time scales. (author)

  17. Bulk Soil Organic Matter d2H as a Precipitation Proxy

    Science.gov (United States)

    Williams, E. K.; Terwilliger, V. J.; Nakamoto, B. J.; Berhe, A. A.; Fogel, M. L.

    2016-12-01

    The stable hydrogen isotopic composition (d2H) of leaf waxes have traditionally been used to infer modern and paleoclimate precipitation sources. However, the extent to which evapotranspiration of leaf waters affects the d2H of plant leaf waxes remains hotly contested with offsets varying between species. Because of the relative importance of root organic matter contribution to bulk soil pools compared to litter/leaves and the minimal fractionation between soil water and root material, it is plausible that bulk soil organic matter d2H may be an option for modern and paleoclimate precipitation reconstructions. In this study, we analyzed the non-exchangeable d2H composition of roots, litter, leaves, and bulk soils along an elevation gradient in the southern Sierra Nevada range (USA). Our results show a consistent offset of 30 ± 3‰ in bulk soil organic matter in surface soils from the measured precipitation. This consistent relationship with precipitation was not found in any of the other organic materials that we measured and implies that d2H bulk soil organic matter can record precipitation signals regardless of above-ground species composition. Additionally, we utilized physical density fractionation to determine which fractions (which vary in level of mineral association and in turnover time) of the soil control this relationship. These findings and how this relationship holds with depth will be presented in conjunction with data from a soil profile on the Ethiopian plateau spanning 6000 years.

  18. Soil organic matter composition and quality across fire severity gradients in coniferous and deciduous forests of the southern boreal region

    Science.gov (United States)

    Jessica R. Miesel; William C. Hockaday; Randy Kolka; Philip A. Townsend

    2015-01-01

    Recent patterns of prolonged regional drought in southern boreal forests of the Great Lakes region, USA, suggest that the ecological effects of disturbance by wildfire may become increasingly severe. Losses of forest soil organic matter (SOM) during fire can limit soil nutrient availability and forest regeneration. These processes are also influenced by the composition...

  19. Influence of long-term land use (arable and forest) and soil mineralogy on organic carbon stocks as well as composition and stability of soil organic matter

    Science.gov (United States)

    Kaiser, M.; Ellerbrock, R. H.; Wulf, M.; Dultz, S.; Hierath, C.; Sommer, M.

    2009-04-01

    The function of soils to sequester organic carbon (OC) and their related potential to mitigate the greenhouse effect is strongly affected by land use and soil mineralogy. This study is aimed to clarify long-term impacts of arable and forest land use as well as soil mineralogy on topsoil soil organic carbon (SOC) stocks as well as soil organic matter (SOM) composition and stability. Topsoil samples were taken from deciduous forest and adjacent arable sites (within Germany) that are continuously used for more than 100 years. The soils are different in genesis (Albic and Haplic Luvisol (AL, HL), Colluvic and Haplic Regosol (CR, HR), Haplic and Vertic Cambisol (HC, VC), Haplic Stagnosol (HSt)). First, particulate and water soluble organic matter were separated from the topsoil samples (Ap and Ah horizons). From the remaining solid extraction residues the Na-pyrophosphate soluble organic matter fractions (OM(PY)) were extracted, analysed for its OC content (OC(PY)) and characterized by FTIR spectroscopy and 14C analyses. The SOC stocks calculated for 0-40 cm depth are in general larger for the forest as compared to the adjacent arable soils (except VC). The largest difference between forest and arable topsoils was detected for the HR site (5.9 kg m-2) and seemed to be caused by a two times larger stock of exchangeable Ca of the forest topsoil. For the arable topsoils multiple regression analyses indicate a strong influence of clay, oxalate soluble Al and pyrophosphate soluble Mg on the content of OC(PY) weighted with its C=O content. Such relation is not found for the forest topsoils. Further, a positive relation between Δ14C values of OM(PY) and the following independent variables: (i) specific mineral surface area, (ii) relative C=O group content in OM(PY) and (iii) soil pH is found for the arable topsoils (pH 6.7 - 7.5) suggesting an increase in OM(PY) stability with increasing interactions between OM(PY) and soil mineral surfaces via cation bridging. A similar

  20. The effect of composition on stability ({sup 14}C activity) of soil organic matter fractions from the albic and black soils

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Jie [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875 (China); Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003 (United States); Sun, Ke, E-mail: sunke@bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875 (China); Wang, Ziying; Han, Lanfang [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875 (China); Wu, Fengchang [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Xing, Baoshan [Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003 (United States)

    2016-01-15

    The importance of the composition of soil organic matter (SOM) for carbon (C) cycling is still under debate. Here a single soil source was used to examine the specific influence of its composition on stability ({sup 14}C activity) of SOM fractions while constraining other influential C turnover factors such as mineral, climate and plant input. The following SOM fractions were isolated from two soil samples: four humic acids, two humins, non-hydrolyzable carbon, and the demineralized fraction. We examined the isotope ratios of SOM fractions in relation to composition (such as aliphatic and aromatic C content) using solid state {sup 13}C nuclear magnetic resonance (NMR) and thermal analysis. The Δ{sup 14}C values of the fractions isolated from both an albic soil (SOMs-A) and a black soil (SOMs-B) correlated negatively with their peak temperature of decomposition and the temperature where half of the total heat of reaction was evolved, implying a potential link between thermal and biogeochemical stability of SOM fractions. Aryl C contents of SOMs-A determined using {sup 13}C NMR varied inversely with δ{sup 15}N values and directly with δ{sup 13}C values, suggesting that part of aryl C of SOMs-A might be fire-derived. The Δ{sup 14}C values of SOMs-A correlated positively with aliphatic C content and negatively with aromatic C content. We therefore concluded that fire-derived aromatic C in SOMs-A appeared to be more stable than microbially-derived aliphatic C. The greater decomposition of SOMs-B fractions weakened the relationship of their Δ{sup 14}C values with alkyl and aryl C contents. Hence, the role of the composition of SOM fractions in regulating stability might be dependent on the source of specific C forms and their stage of decomposition. - Highlights: • The effect of composition on stability of SOM fractions (SOMs) was examined. • There was a potential link between thermal and biological stability of SOMs. • Fire-derived aromatic C was likely more

  1. The effect of composition on stability ("1"4C activity) of soil organic matter fractions from the albic and black soils

    International Nuclear Information System (INIS)

    Jin, Jie; Sun, Ke; Wang, Ziying; Han, Lanfang; Wu, Fengchang; Xing, Baoshan

    2016-01-01

    The importance of the composition of soil organic matter (SOM) for carbon (C) cycling is still under debate. Here a single soil source was used to examine the specific influence of its composition on stability ("1"4C activity) of SOM fractions while constraining other influential C turnover factors such as mineral, climate and plant input. The following SOM fractions were isolated from two soil samples: four humic acids, two humins, non-hydrolyzable carbon, and the demineralized fraction. We examined the isotope ratios of SOM fractions in relation to composition (such as aliphatic and aromatic C content) using solid state "1"3C nuclear magnetic resonance (NMR) and thermal analysis. The Δ"1"4C values of the fractions isolated from both an albic soil (SOMs-A) and a black soil (SOMs-B) correlated negatively with their peak temperature of decomposition and the temperature where half of the total heat of reaction was evolved, implying a potential link between thermal and biogeochemical stability of SOM fractions. Aryl C contents of SOMs-A determined using "1"3C NMR varied inversely with δ"1"5N values and directly with δ"1"3C values, suggesting that part of aryl C of SOMs-A might be fire-derived. The Δ"1"4C values of SOMs-A correlated positively with aliphatic C content and negatively with aromatic C content. We therefore concluded that fire-derived aromatic C in SOMs-A appeared to be more stable than microbially-derived aliphatic C. The greater decomposition of SOMs-B fractions weakened the relationship of their Δ"1"4C values with alkyl and aryl C contents. Hence, the role of the composition of SOM fractions in regulating stability might be dependent on the source of specific C forms and their stage of decomposition. - Highlights: • The effect of composition on stability of SOM fractions (SOMs) was examined. • There was a potential link between thermal and biological stability of SOMs. • Fire-derived aromatic C was likely more stable than microbial

  2. Measurement of organic carbon stable isotope composition of different soil types by EA-IRMS system

    International Nuclear Information System (INIS)

    Qi Biao; Ding Lingling; Cui Jiehua; Wang Yanhong

    2009-01-01

    Element analyzer-isotope ratio mass spectrometers (EA-IRMS) is a rapid and precise method for measuring stable carbon isotope. Pure CO 2 reference gas was calibrated via international standard-Urea, and the δ 13 C us PDB value of pure CO 2 is (-29.523 ± 0.0181)%. Stability and linearity of the EA-IRMS system, precision of δ 13 C measurement for samples were tested through experimental comparison. Moreover, determination method of organic carbon stable isotope in soil was based on the system. The EA-IRMS system had well linearity when ion intensity ranged from 1.0 to 7.0V, and it excelled the total linearity when the ion intensity was from 1.5 to 5.0V, and the accurate result of δ 13 C for sample analysis could be obtained with precision of 0.015%. If carbon content in sample is more than 5μg, the requirement for analyzing accurate result of δ 13 C could be achieved. The organic carbon stable isotope was measured in 18 different types soil samples, the average natural abundance of 13 C was 1.082%, and the organic carbon stable isotope composition was significantly different among different type soils. (authors)

  3. [Influences of long-term application of organic and inorganic fertilizers on the composition and abundance of nirS-type denitrifiers in black soil].

    Science.gov (United States)

    Yin, Chang; Fan, Fen-Liang; Li, Zhao-Jun; Song, A-Lin; Zhu, Ping; Peng, Chang; Liang, Yong-Chao

    2012-11-01

    The objectives of this study were to explore the effects of long-term organic and inorganic fertilizations on the composition and abundance of nirS-type denitrifiers in black soil. Soil samples were collected from 4 treatments (i. e. no fertilizer treatment, CK; organic manure treatment, OM; chemical fertilizer treatment (NPK) and combination of organic and chemical fertilizers treatment (MNPK)) in Gongzhuling Long-term Fertilization Experiment Station. Composition and abundance of nirS-type denitrifiers were analyzed with terminal restriction fragment length polymorphism (T-RFLP) and real-time quantitative PCR (Q-PCR), respectively. Denitrification enzyme activity (DEA) and soil properties were also measured. Application of organic fertilizers (OM and MNPK) significantly increased the DEAs of black soil, with the DEAs in OM and MNPK being 5.92 and 6.03 times higher than that in CK treatment, respectively, whereas there was no significant difference between NPK and CK. OM and MNPK treatments increased the abundances of nirS-type denitrifiers by 2.73 and 3.83 times relative to that of CK treatment, respectively. The abundance of nirS-type denitrifiers in NPK treatment was not significantly different from that of CK. The T-RFLP analysis of nirS genes showed significant differences in community composition between organic and inorganic treatments, with the emergence of a 79 bp T-RF, a significant decrease in relative abundance of the 84 bp T-RF and a loss of the 99 bp T-RF in all organic treatments. Phylogenetic analysis indicated that the airS-type denitrifiers in the black soil were mainly composed of alpha, beta and gamma-Proteobacteria. The 79 bp-type denitrifiers inhabiting exclusively in organic treatments (OM and MNPK) were affiliated to Pseudomonadaceae in gamma-Proteobacteria and Burkholderiales in beta-Proteobacteria. The 84 bp-types were related to Burkholderiales and Rhodocyclales. Correlation analysis indicated that pH, concentrations of total nitrogen

  4. Soil Fauna Alter the Effects of Litter Composition on Nitrogen Cycling in a Mineral Soil

    Science.gov (United States)

    Plant chemical composition and the soil community are known to influence litter and soil organic matter decomposition. Although these two factors are likely to interact, their mechanisms and outcomes of interaction are not well understood. Studies of their interactive effects are...

  5. Peat decomposability in managed organic soils in relation to land use, organic matter composition and temperature

    Science.gov (United States)

    Bader, Cédric; Müller, Moritz; Schulin, Rainer; Leifeld, Jens

    2018-02-01

    Organic soils comprise a large yet fragile carbon (C) store in the global C cycle. Drainage, necessary for agriculture and forestry, triggers rapid decomposition of soil organic matter (SOM), typically increasing in the order forest accrual of labile crop residues. A comparison with published CO2 rates from incubated mineral soils indicated no difference in SOM decomposability between these soil classes, suggesting that accumulation of recent, labile plant materials that presumably account for most of the evolved CO2 is not systematically different between mineral and organic soils. In our data set, temperature sensitivity of decomposition (Q10 on average 2.57 ± 0.05) was the same for all land uses but lowest below 60 cm in croplands and grasslands. This, in turn, indicates a relative accumulation of recalcitrant peat in topsoils.

  6. Soil amino acid composition across a boreal forest successional sequence

    Science.gov (United States)

    Nancy R. Werdin-Pfisterer; Knut Kielland; Richard D. Boone

    2009-01-01

    Soil amino acids are important sources of organic nitrogen for plant nutrition, yet few studies have examined which amino acids are most prevalent in the soil. In this study, we examined the composition, concentration, and seasonal patterns of soil amino acids across a primary successional sequence encompassing a natural gradient of plant productivity and soil...

  7. Impact of long-term organic residue recycling in agriculture on soil solution composition and trace metal leaching in soils.

    Science.gov (United States)

    Cambier, Philippe; Pot, Valérie; Mercier, Vincent; Michaud, Aurélia; Benoit, Pierre; Revallier, Agathe; Houot, Sabine

    2014-11-15

    Recycling composted organic residues in agriculture can reduce the need of mineral fertilizers and improve the physicochemical and biological properties of cultivated soils. However, some trace elements may accumulate in soils following repeated applications and impact other compartments of the agrosystems. This study aims at evaluating the long-term impact of such practices on the composition of soil leaching water, especially on trace metal concentrations. The field experiment QualiAgro started in 1998 on typical loess Luvisol of the Paris Basin, with a maize-wheat crop succession and five modalities: spreading of three different urban waste composts, farmyard manure (FYM), and no organic amendment (CTR). Inputs of trace metals have been close to regulatory limits, but supplies of organic matter and nitrogen overpassed common practices. Soil solutions were collected from wick lysimeters at 45 and 100 cm in one plot for each modality, during two drainage periods after the last spreading. Despite wide temporal variations, a significant effect of treatments on major solutes appears at 45 cm: DOC, Ca, K, Mg, Na, nitrate, sulphate and chloride concentrations were higher in most amended plots compared to CTR. Cu concentrations were also significantly higher in leachates of amended plots compared to CTR, whereas no clear effect emerged for Zn. The influence of amendments on solute concentrations appeared weaker at 1 m than at 45 cm, but still significant and positive for major anions and DOC. Average concentrations of Cu and Zn at 1m depth lied in the ranges [2.5; 3.8] and [2.5; 10.5 μg/L], respectively, with values slightly higher for plots amended with sewage sludge compost or FYM than for CTR. However, leaching of both metals was less than 1% of their respective inputs through organic amendments. For Cd, most values were <0.05 μg/L. So, metals added through spreading of compost or manure during 14 years may have increased metal concentrations in leachates of

  8. A Molecular Investigation of Soil Organic Carbon Composition, Variability, and Spatial Distribution Across an Alpine Catchment

    Science.gov (United States)

    Hsu, H. T.; Lawrence, C. R.; Winnick, M.; Druhan, J. L.; Williams, K. H.; Maher, K.; Rainaldi, G. R.; McCormick, M. E.

    2016-12-01

    The cycling of carbon through soils is one of the least understood aspects of the global carbon cycle and represents a key uncertainty in the prediction of land-surface response to global warming. Thus, there is an urgent need for advanced characterization of soil organic carbon (SOC) to develop and evaluate a new generation of soil carbon models. We hypothesize that shifts in SOC composition and spatial distribution as a function of soil depth can be used to constrain rates of transformation between the litter layer and the deeper subsoil (extending to a depth of approximately 1 m). To evaluate the composition and distribution of SOC, we collected soil samples from East River, a shale-dominated watershed near Crested Butte, CO, and characterized relative changes in SOC species as a function of depth using elemental analysis (EA), Fourier transform infrared spectroscopy (FT-IR) and bulk C X-ray absorption spectroscopy (XAS). Our results show that total organic carbon (TOC) decreases with depth, and high total inorganic carbon (TIC) content was found in deeper soils (after 75 cm), a characteristic of the bedrock (shale). The distribution of aliphatic C relative to the parent material generally decreases with depth and that polysaccharide can be a substantial component of SOC at various depths. On the other hand, the relative distribution of aromatic C, traditionally viewed as recalcitrant, only makes up a very small part of SOC regardless of depth. These observations confirm that molecular structure is not the only determinant of SOC turnover rate. To study other contributors to SOC decomposition, we studied changes in the spatial correlation of SOC and minerals using X-ray fluorescence spectroscopy (XRF) and scanning transmission X-ray microscopy (STXM). We found that aromatics mostly locate on the surface of small soil aggregates (1-10 μm). Polysaccharides and proteins, both viewed as labile traditionally, are more evenly distributed over the interior of the

  9. Influence of organic components onto state of radioactive strontium in soils

    International Nuclear Information System (INIS)

    Sokolik, G.A.; Ovsyannikova, S.V.; Cherevko, E.S.; Rubinchik, S.Ya.

    2005-01-01

    Influence of soil organic components onto radioactive strontium mobility in the soil medium has been analyzed. Distribution of the Sr 90 between various organic fractions of soils having different quantitative and qualitative composition of organic matter has been studied. The samples of mineral and organic soils contaminated by radionuclides of Chernobyl origin were used as the objects of investigation. Fulvic- and humic-acid fractions differed in solubility and mobility in a soil medium have been separated. Differentiation of soils on the Sr 90 mobility in accordance with portion of radionuclide in the immobile organic fractions has been fulfilled. New types of organic and organomineral additives decreased mobility and biological availability of the Sr 90 have been suggested on a base of obtained data. (authors)

  10. [The influence of root excretions of germinating barley seed (Hordeum vulgare L.) on qualitative and quantitative composition of soil organic components].

    Science.gov (United States)

    Volkov, O I

    2010-01-01

    The data from scientific publications on excretory activity of herbs root endings were analyzed, along with the data on the role of polyvalent metals cations in stabilization of humus substances (HS) of soil organic mineral complex. On the base of the analysis a working hypothesis was proposed considering root endings influence on fractional composition of soil organic components. To detect the changes taking place in soil HS, the chromatographic fractionation method was chosen. The soil aggregates stuck to root endings of germinating barley seed were washed off, and the washouts were used as the samples for the analysis. The soil from the weighed portion was dissolved directly with extenuating concentrations of LiCl and Li2SO4 alkaline solution. The fractionation was carried out in a chromatographic column. Some changes were detected in optical density of chernozem and dark-grey forest soil leached out after 1-2 days of barley seeds germination. Besides, the experiment showed that the content of organic carbon in HS changes as well.

  11. Soil organic matter composition and quality across fire severity gradients in coniferous and deciduous forests of the southern boreal region

    Science.gov (United States)

    Miesel, Jessica R.; Hockaday, William C.; Kolka, Randall K.; Townsend, Philip A.

    2015-06-01

    Recent patterns of prolonged regional drought in southern boreal forests of the Great Lakes region, USA, suggest that the ecological effects of disturbance by wildfire may become increasingly severe. Losses of forest soil organic matter (SOM) during fire can limit soil nutrient availability and forest regeneration. These processes are also influenced by the composition of postfire SOM. We sampled the forest floor layer (i.e., full organic horizon) and 0-10 cm mineral soil from stands dominated by coniferous (Pinus banksiana Lamb.) or deciduous (Populus tremuloides Michx.) species 1-2 months after the 2011 Pagami Creek wildfire in northern Minnesota. We used solid-state 13C NMR to characterize SOM composition across a gradient of fire severity in both forest cover types. SOM composition was affected by fire, even when no statistically significant losses of total C stocks were evident. The most pronounced differences in SOM composition between burned and unburned reference areas occurred in the forest floor for both cover types. Carbohydrate stocks in forest floor and mineral horizons decreased with severity level in both cover types, whereas pyrogenic C stocks increased with severity in the coniferous forest floor and decreased in only the highest severity level in the deciduous forest floor. Loss of carbohydrate and lignin pools contributed to a decreased SOM stability index and increased decomposition index. Our results suggest that increases in fire severity expected to occur under future climate scenarios may lead to changes in SOM composition and dynamics with consequences for postfire forest recovery and C uptake.

  12. Some Remarks on Practical Aspects of Laboratory Testing of Deep Soil Mixing Composites Achieved in Organic Soils

    Science.gov (United States)

    Kanty, Piotr; Rybak, Jarosław; Stefaniuk, Damian

    2017-10-01

    This paper presents the results of laboratory testing of organic soil-cement samples are presented in the paper. The research program continues previously reported the authors’ experiences with cement-fly ash-soil sample testing. Over 100 of compression and a dozen of tension tests have been carried out altogether. Several samples were waiting for failure test for over one year after they were formed. Several factors, like: the large amount of the tested samples, a long observation time, carrying out the tests in complex cycles of loading and the possibility of registering the loads and deformation in the axial and lateral direction - have made it possible to take into consideration numerous interdependencies, three of which have been presented in this work: the increments of compression strength, the stiffness of soil-cement in relation to strength and the tensile strength. Compressive strength, elastic modulus and tensile resistance of cubic samples were examined. Samples were mixed and stored in the laboratory conditions. Further numerical analysis in the Finite Element Method numerical code Z_Soil, were performed on the basis of laboratory test results. Computations prove that cement-based stabilization of organic soil brings serious risks (in terms of material capacity and stiffness) and Deep Soil Mixing technology should not be recommended for achieving it. The numerical analysis presented in the study below includes only one type of organic and sandy soil and several possible geometric combinations. Despite that, it clearly points to the fact that designing the DSM columns in the organic soil may be linked with a considerable risk and the settlement may reach too high values. During in situ mixing, the organic material surrounded by sand layers surely mixes with one another in certain areas. However, it has not been examined and it is difficult to assume such mixing already at the designing stage. In case of designing the DSM columns which goes through a

  13. Soil biota and agriculture production in conventional and organic farming

    Science.gov (United States)

    Schrama, Maarten; de Haan, Joj; Carvalho, Sabrina; Kroonen, Mark; Verstegen, Harry; Van der Putten, Wim

    2015-04-01

    pronounced shifts in soil fauna composition (nematodes, earthworms) and an increase in earthworm activity. Hence, more buffered conditions and shifts in soil fauna composition under organic farming may underlie the observed reduction in spatial variation of soil chemical and biological parameters, which in turn correlates positively with a long-term increase in yield. Our study highlights the need for both policymakers and farmers alike to support spatial stability-increasing farming.

  14. New Approaches in Soil Organic Matter Fluorescence; A Solid Phase Fluorescence Approach

    Science.gov (United States)

    Bowman, M. M.; Sanclements, M.; McKnight, D. M.

    2017-12-01

    Fluorescence spectroscopy is a well-established technique to investigate the composition of organic matter in aquatic systems and is increasingly applied to soil organic matter (SOM). Current methods require that SOM be extracted into a liquid prior to analysis by fluorescence spectroscopy. Soil extractions introduce an additional layer of complexity as the composition of the organic matter dissolved into solution varies based upon the selected extractant. Water is one of the most commonly used extractant, but only extracts the water-soluble fraction of the SOM with the insoluble soil organic matter fluorescence remaining in the soil matrix. We propose the use of solid phase fluorescence on whole soils as a potential tool to look at the composition of organic matter without the extraction bias and gain a more complete understand of the potential for fluorescence as a tool in terrestrial studies. To date, the limited applications of solid phase fluorescence have ranged from food and agriculture to pharmaceutical with no clearly defined methods and limitations available. We are aware of no other studies that use solid phase fluorescence and thus no clear methods to look at SOM across a diverse set of soil types and ecosystems. With this new approach to fluorescence spectroscopy there are new challenges, such as blank correction, inner filter effect corrections, and sample preparation. This work outlines a novel method for analyzing soil organic matter using solid phase fluorescence across a wide range of soils collected from the National Ecological Observatory Network (NEON) eco-domains. This method has shown that organic matter content in soils must be diluted to 2% to reduce backscattering and oversaturation of the detector in forested soils. In mineral horizons (A) there is observed quenching of the humic-like organic matter, which is likely a result of organo-mineral complexation. Finally, we present preliminary comparisons between solid and liquid phase

  15. Variability of Effective Micro-organisms (EM) in bokashi and soil and effects on soil-borne plant pathogens

    NARCIS (Netherlands)

    Shin, Keumchul; Diepen, van G.; Blok, W.; Bruggen, van A.H.C.

    2017-01-01

    The microbial inoculant ‘Effective Microorganisms’ (EM) has been used to promote soil fertility and plant growth in agriculture. We tested effects of commercial EM products on suppression of soil-borne diseases, microbial activity and bacterial composition in organically managed sandy soils. EM was

  16. Legacy effects of anaerobic soil disinfestation on soil bacterial community composition and production of pathogen-suppressing volatiles

    Directory of Open Access Journals (Sweden)

    Maaike evan Agtmaal

    2015-07-01

    Full Text Available There is increasing evidence that microbial volatiles (VOCs play an important role in natural suppression of soil-borne diseases, but little is known on the factors that influence production of suppressing VOCs. In the current study we examined whether a stress-induced change in soil microbial community composition would affect the production by soils of VOCs suppressing the plant-pathogenic oomycete Pythium. Using pyrosequencing of 16S ribosomal gene fragments we compared the composition of bacterial communities in sandy soils that had been exposed to anaerobic disinfestation (AD, a treatment used to kill harmful soil organisms, with the composition in untreated soils. Three months after the AD treatment had been finished, there was still a clear legacy effect of the former anaerobic stress on bacterial community composition with a strong increase in relative abundance of the phylum Bacteroidetes and a significant decrease of the phyla Acidobacteria, Planctomycetes, Nitrospirae, Chloroflexi and Chlorobi. This change in bacterial community composition coincided with loss of production of Pythium suppressing soil volatiles (VOCs and of suppression of Pythium impacts on Hyacinth root development. One year later, the composition of the bacterial community in the AD soils was reflecting that of the untreated soils. In addition, both production of Pythium-suppressing VOCs and suppression of Pythium in Hyacinth bioassays had returned to the levels of the untreated soil. GC/MS analysis identified several VOCs, among which compounds known to be antifungal, that were produced in the untreated soils but not in the AD soils. These compounds were again produced 15 months after the AD treatment. Our data indicate that soils exposed to a drastic stress can temporarily lose pathogen suppressive characteristics and that both loss and return of these suppressive characteristics coincides with shifts in the soil bacterial community composition. Our data are

  17. Differences in chemical composition of soil organic matter in natural ecosystems from different climatic regions: a pyrolysis-GC/MS study

    NARCIS (Netherlands)

    Vancampenhout, K.; Wouters, K.; Vos, de B.; Buurman, P.; Swennen, R.; Deckers, J.

    2009-01-01

    Soil organic matter (SOM) is a key factor in ecosystem dynamics. A better understanding of the global relationship between environmental characteristics, ecosystems and SOM chemistry is vital in order to assess its specific influence on carbon cycles. This study compared the composition of extracted

  18. Soil Organic Matter Erosion by Interrill Processes from Organically and Conventionally farmed Devon Soil

    Science.gov (United States)

    Armstrong, E.; Ling, A.; Kuhn, N. J.

    2012-04-01

    that the net P export from organically farmed soils is not reduced by a similar degree than soil erosion compared to conventional soil management. The enrichment of P and C in the interrill sediment was not directly related to SOC, P content of the soil and soil interrill erodibility. A comparison of soil and sediment properties indicates that crusting, P and C content as well as density and size of eroded aggregate fragments control P and C enrichment. Due to complex and dynamic interactions between P, SOC and interrill erosional processes, the nutrient and C status of sediments cannot be predicted based on soil P content, SOC or interrill erodibility alone. Clearly, further research on crust formation and the composition of fragments generated by aggregate breakdown and their transport in raindrop impacted flow under different rainfall conditions is required. Attaining this critical missing knowledge would enable a comprehensive assessment of the benefits of organic farming on nutrient budgets, off-site effects of interrill erosion and its role in the global C cycle.

  19. Humic Substances in Organic Wastes and their Effects on Amended Soils

    Science.gov (United States)

    Senesi, N.; Ciavatta, C.; Plaza, C.

    2009-04-01

    Soil humic substances (HS) are universally recognized to play a major role in a wide number of agronomic and environmental processes. For example, soil HS are able to bind mineral particles together, thus promoting a good soil structure, constitute an important source of nutrients for plants and microorganisms, contribute largely to the acid-base buffering capacity of soils, and exert a marked control on the biological availability, physico-chemical behavior, and environmental fate of toxic metal ions and xenobiotics. For these reasons, the knowledge of the short- and long-term effects of organic amendments on the status, quality, and reactivity of indigenous soil HS is of paramount importance. The objective of this presentation is to provide an overview of the chemical and physico-chemical data available in the literature for the evaluation of the effects of organic wastes of various origin and nature used as soil amendments on the composition, structure, and chemical reactivity of native soil HS. In general, HS-like components of organic wastes are typically characterized by a relatively larger presence of aliphatic, amide, and polysaccharide structures, simple structural components of wide molecular heterogeneity, smaller contents of oxygen, acidic functional groups, and organic free radicals, and smaller degrees of aromatic ring polycondensation, polymerization, and humification than native soil HS. Further, with respect to native soil HS, HS-like fractions from organic wastes generally exhibit smaller binding capacities and affinities for metal ions and organic xenobiotics. Appropriate treatment processes of raw organic wastes able to produce environmentally safe and agronomically efficient soil amendments, such as composting, yield HS-like fractions characterized by chemical and physico-chemical features that approach those of native soil HS. In general, aliphatic, polysaccharide, and lignin structures and S- and N-containing groups of the HS-like fractions

  20. Influences upon the lead isotopic composition of organic and mineral horizons in soil profiles from the National Soil Inventory of Scotland (2007–09)

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, John G., E-mail: J.G.Farmer@ed.ac.uk [School of GeoSciences, The University of Edinburgh, Crew Building, Alexander Crum Brown Road, Edinburgh, EH9 3FF Scotland (United Kingdom); Graham, Margaret C. [School of GeoSciences, The University of Edinburgh, Crew Building, Alexander Crum Brown Road, Edinburgh, EH9 3FF Scotland (United Kingdom); Eades, Lorna J. [School of Chemistry, The University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ Scotland (United Kingdom); Lilly, Allan; Bacon, Jeffrey R. [James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH Scotland (United Kingdom)

    2016-02-15

    Some 644 individual soil horizons from 169 sites in Scotland were analyzed for Pb concentration and isotopic composition. There were three scenarios: (i) 36 sites where both top and bottom (i.e. lowest sampled) soil horizons were classified as organic in nature, (ii) 67 with an organic top but mineral bottom soil horizon, and (iii) 66 where both top and bottom soil horizons were mineral. Lead concentrations were greater in the top horizon relative to the bottom horizon in all but a few cases. The top horizon {sup 206}Pb/{sup 207}Pb ratio was lesser (outside analytical error) than the corresponding bottom horizon {sup 206}Pb/{sup 207}Pb ratio at (i) 64%, (ii) 94% and (iii) 73% of sites, and greater at only (i) 8%, (ii) 3% and (iii) 8% of sites. A plot of {sup 208}Pb/{sup 207}Pb vs. {sup 208}Pb/{sup 206}Pb ratios showed that the Pb in organic top (i, ii) and bottom (i) horizons was consistent with atmospherically deposited Pb of anthropogenic origin. The {sup 206}Pb/{sup 207}Pb ratio of the organic top horizon in (ii) was unrelated to the {sup 206}Pb/{sup 207}Pb ratio of the mineral bottom horizon as demonstrated by the geographical variation in the negative shift in the ratio, a result of differences in the mineral horizon values arising from the greater influence of radiogenic Pb in the north. In (iii), the lesser values of the {sup 206}Pb/{sup 207}Pb ratio for the mineral top horizon relative to the mineral bottom horizon were consistent with the presence of anthropogenic Pb, in addition to indigenous Pb, in the former. Mean anthropogenic Pb inventories of 1.5 and 4.5 g m{sup −2} were obtained for the northern and southern halves of Scotland, respectively, consistent with long-range atmospheric transport of anthropogenic Pb (mean {sup 206}Pb/{sup 207}Pb ratio ~ 1.16). For cultivated agricultural soils (Ap), this corresponded to about half of the total Pb inventory in the top 30 cm of the soil column. - Highlights: • Pb isotope ratios were determined for 644

  1. Soil organic matter studies

    International Nuclear Information System (INIS)

    1977-01-01

    A total of 77 papers were presented and discussed during this symposium, 37 are included in this Volume II. The topics covered in this volume include: biochemical transformation of organic matter in soils; bitumens in soil organic matter; characterization of humic acids; carbon dating of organic matter in soils; use of modern techniques in soil organic matter research; use of municipal sludge with special reference to heavy metals constituents, soil nitrogen, and physical and chemical properties of soils; relationship of soil organic matter and plant metabolism; interaction between agrochemicals and organic matter; and peat. Separate entries have been prepared for those 20 papers which discuss the use of nuclear techniques in these studies

  2. Associations between soil bacterial community structure and nutrient cycling functions in long-term organic farm soils following cover crop and organic fertilizer amendment.

    Science.gov (United States)

    Fernandez, Adria L; Sheaffer, Craig C; Wyse, Donald L; Staley, Christopher; Gould, Trevor J; Sadowsky, Michael J

    2016-10-01

    Agricultural management practices can produce changes in soil microbial populations whose functions are crucial to crop production and may be detectable using high-throughput sequencing of bacterial 16S rRNA. To apply sequencing-derived bacterial community structure data to on-farm decision-making will require a better understanding of the complex associations between soil microbial community structure and soil function. Here 16S rRNA sequencing was used to profile soil bacterial communities following application of cover crops and organic fertilizer treatments in certified organic field cropping systems. Amendment treatments were hairy vetch (Vicia villosa), winter rye (Secale cereale), oilseed radish (Raphanus sativus), buckwheat (Fagopyrum esculentum), beef manure, pelleted poultry manure, Sustane(®) 8-2-4, and a no-amendment control. Enzyme activities, net N mineralization, soil respiration, and soil physicochemical properties including nutrient levels, organic matter (OM) and pH were measured. Relationships between these functional and physicochemical parameters and soil bacterial community structure were assessed using multivariate methods including redundancy analysis, discriminant analysis, and Bayesian inference. Several cover crops and fertilizers affected soil functions including N-acetyl-β-d-glucosaminidase and β-glucosidase activity. Effects, however, were not consistent across locations and sampling timepoints. Correlations were observed among functional parameters and relative abundances of individual bacterial families and phyla. Bayesian analysis inferred no directional relationships between functional activities, bacterial families, and physicochemical parameters. Soil functional profiles were more strongly predicted by location than by treatment, and differences were largely explained by soil physicochemical parameters. Composition of soil bacterial communities was predictive of soil functional profiles. Differences in soil function were

  3. Composition of structural fragments and the mineralization rate of organic matter in zonal soils

    Science.gov (United States)

    Larionova, A. A.; Zolotareva, B. N.; Kolyagin, Yu. G.; Kvitkina, A. K.; Kaganov, V. V.; Kudeyarov, V. N.

    2015-10-01

    Comparative analysis of the climatic characteristics and the recalcitrance against decomposition of organic matter in the zonal soil series of European Russia, from peat surface-gley tundra soil to brown semidesert soil, has assessed the relationships between the period of biological activity, the content of chemically stable functional groups, and the mineralization of humus. The stability of organic matter has been determined from the ratio of functional groups using the solid-state 13C NMR spectroscopy of soil samples and the direct measurements of organic matter mineralization from CO2 emission. A statistically significant correlation has been found between the period of biological activity and the humification indices: the CHA/CFA ratio, the aromaticity, and the alkyl/ O-alkyl ratio in organic matter. The closest correlation has been observed between the period of biological activity and the alkyl/ O-alkyl ratio; therefore, this parameter can be an important indicator of the soil humus status. A poor correlation between the mineralization rate and the content of chemically stable functional groups in soil organic matter has been revealed for the studied soil series. At the same time, the lowest rate of carbon mineralization has been observed in southern chernozem characterized by the maximum content of aromatic groups (21% Corg) and surface-gley peat tundra soil, where an extremely high content of unsubstituted CH2 and CH3 alkyl groups (41% Corg) has been noted.

  4. Impact of charcoal waste application on the soil organic matter content and composition of an Haplic Cambisol from South Brazil

    Science.gov (United States)

    dos Anjos Leal, Otávio; Pinheiro Dick, Deborah; Cylene Lombardi, Kátia; Gonçalves Maciel, Vanessa

    2014-05-01

    In some regions in Brazil, charcoal is usually applied to the soil with the purpose to improve its fertility and its organic carbon (SOC) content. In Brazil, the use of charcoal waste from steel industry with agronomic purposes represents also an alternative and sustainable fate for this material. In this context, the objective of this work was to evaluate the impact of Eucalyptus charcoal waste application on the SOC content and on the soil organic matter (SOM) composition. Increasing doses of charcoal (0, 10, 20 and 40 Mg ha-1) were applied to an Haplic Cambisol, in Irati, South-Brazil. Charcoal was initially applied on the soil surface, and then it was incorporated at 10 cm with a harrow. Soil undisturbed and disturbed samples (four replicates) were collected in September 2011 (1 y and 9 months) after charcoal incorporation. Four soil depths were evaluated (0-5, 5-10, 10-20 and 20-30 cm) and each replicate was composed by three subsamples collected within each plot. The soil samples were air dried, passed through a 9.51 mm sieve and thereafter through a 2.00 mm sieve. The SOC content and total N were quantified by dry combustion. The SOM was concentrated with fluoridric acid 10% and then the SOM composition was evaluated by thermogravimetric analysis along the soil profile. The main impact of charcoal application occurred at the 0-5 cm layer of the area treated with the highest dose: SOC content increased in 15.5 g kg-1 in comparison to the soil without charcoal application. The intermediary doses also increased the SOC content, but the differences were not significant. No differences for N content were found in this soil depth. Further results were observed in the 10-20 cm soil depth, where the highest dose increased the SOC content and N content. Furthermore, this treatment increased the recalcitrance of the SOM, mainly at the 0-5 cm and 10-20 cm soil layers. No differences between doses of charcoal application were found in the 20-30 cm soil depth, suggesting

  5. Organic nitrogen rearranges both structure and activity of the soil-borne microbial seedbank.

    Science.gov (United States)

    Leite, Márcio F A; Pan, Yao; Bloem, Jaap; Berge, Hein Ten; Kuramae, Eiko E

    2017-02-15

    Use of organic amendments is a valuable strategy for crop production. However, it remains unclear how organic amendments shape both soil microbial community structure and activity, and how these changes impact nutrient mineralization rates. We evaluated the effect of various organic amendments, which range in Carbon/Nitrogen (C/N) ratio and degradability, on the soil microbiome in a mesocosm study at 32, 69 and 132 days. Soil samples were collected to determine community structure (assessed by 16S and 18S rRNA gene sequences), microbial biomass (fungi and bacteria), microbial activity (leucine incorporation and active hyphal length), and carbon and nitrogen mineralization rates. We considered the microbial soil DNA as the microbial seedbank. High C/N ratio favored fungal presence, while low C/N favored dominance of bacterial populations. Our results suggest that organic amendments shape the soil microbial community structure through a feedback mechanism by which microbial activity responds to changing organic inputs and rearranges composition of the microbial seedbank. We hypothesize that the microbial seedbank composition responds to changing organic inputs according to the resistance and resilience of individual species, while changes in microbial activity may result in increases or decreases in availability of various soil nutrients that affect plant nutrient uptake.

  6. Little effects on soil organic matter chemistry of density fractions after seven years of forest soil warming.

    Science.gov (United States)

    Schnecker, Jörg; Borken, Werner; Schindlbacher, Andreas; Wanek, Wolfgang

    2016-12-01

    Rising temperatures enhance microbial decomposition of soil organic matter (SOM) and thereby increase the soil CO 2 efflux. Elevated decomposition rates might differently affect distinct SOM pools, depending on their stability and accessibility. Soil fractions derived from density fractionation have been suggested to represent SOM pools with different turnover times and stability against microbial decomposition. To investigate the effect of soil warming on functionally different soil organic matter pools, we here investigated the chemical and isotopic composition of bulk soil and three density fractions (free particulate organic matter, fPOM; occluded particulate organic matter, oPOM; and mineral associated organic matter, MaOM) of a C-rich soil from a long-term warming experiment in a spruce forest in the Austrian Alps. At the time of sampling, the soil in this experiment had been warmed during the snow-free period for seven consecutive years. During that time no thermal adaptation of the microbial community could be identified and CO 2 release from the soil continued to be elevated by the warming treatment. Our results, which included organic carbon content, total nitrogen content, δ 13 C, Δ 14 C, δ 15 N and the chemical composition, identified by pyrolysis-GC/MS, showed no significant differences in bulk soil between warming treatment and control. Surprisingly, the differences in the three density fractions were mostly small and the direction of warming induced change was variable with fraction and soil depth. Warming led to reduced N content in topsoil oPOM and subsoil fPOM and to reduced relative abundance of N-bearing compounds in subsoil MaOM. Further, warming increased the δ 13 C of MaOM at both sampling depths, reduced the relative abundance of carbohydrates while it increased the relative abundance of lignins in subsoil oPOM. As the size of the functionally different SOM pools did not significantly change, we assume that the few and small

  7. Humic substances elemental composition of selected taiga and tundra soils from Russian European North-East

    Directory of Open Access Journals (Sweden)

    Lodygin Evgeny

    2017-06-01

    Full Text Available Soils of Russian European North were investigated in terms of stability and quality of organic matter as well as in terms of soils organic matter elemental composi­tion. Therefore, soil humic acids (HAs, extracted from soils of different natural zones of Russian North-East were studied to characterize the degree of soil organic matter stabilization along a zonal gradient. HAs were extracted from soil of different zonal environments of the Komi Republic: south, middle and north taiga as well as south tundra. Data on elemental composition of humic acids and fulvic acids (FAs extracted from different soil types were obtained to assess humus formation mechanisms in the soils of taiga and tundra of the European North-East of Russia. The specificity of HAs elemental composition are discussed in relation to environmental conditions. The higher moisture degree of taiga soils results in the higher H/C ratio in humic substances. This reflects the reduced microbiologic activity in Albeluvisols sods and subsequent conser­vation of carbohydrate and amino acid fragments in HAs. HAs of tundra soils, shows the H/C values decreasing within the depth of the soils, which reflects increasing of aromatic compounds in HA structure of mineral soil horizons. FAs were more oxidized and contains less carbon while compared with the HAs. Humic acids, extracted from soil of different polar and boreal environments differ in terms of elemental composition winch reflects the climatic and hydrological regimes of humification.

  8. Carbon and nitrogen molecular composition of soil organic matter fractions resistant to oxidation

    Science.gov (United States)

    Katherine Heckman; Dorisel Torres; Christopher Swanston; Johannes Lehmann

    2017-01-01

    The methods used to isolate and characterise pyrogenic organic carbon (PyC) from soils vary widely, and there is little agreement in the literature as to which method truly isolates the most chemically recalcitrant (inferred from oxidative resistance) and persistent (inferred from radiocarbon abundance) fraction of soil organic matter. In addition, the roles of fire,...

  9. Soil organic matter

    International Nuclear Information System (INIS)

    1976-01-01

    The nature, content and behaviour of the organic matter, or humus, in soil are factors of fundamental importance for soil productivity and the development of optimum conditions for growth of crops under diverse temperate, tropical and arid climatic conditions. In the recent symposium on soil organic matter studies - as in the two preceding ones in 1963 and 1969 - due consideration was given to studies involving the use of radioactive and stable isotopes. However, the latest symposium was a departure from previous efforts in that non-isotopic approaches to research on soil organic matter were included. A number of papers dealt with the behaviour and functions of organic matter and suggested improved management practices, the use of which would contribute to increasing agricultural production. Other papers discussed the turnover of plant residues, the release of plant nutrients through the biodegradation of organic compounds, the nitrogen economy and the dynamics of transformation of organic forms of nitrogen. In addition, consideration was given to studies on the biochemical transformation of organic matter, characterization of humic acids, carbon-14 dating and the development of modern techniques and their impact on soil organic matter research

  10. Complete and Partial Photo-oxidation of Dissolved Organic Matter Draining Permafrost Soils.

    Science.gov (United States)

    Ward, Collin P; Cory, Rose M

    2016-04-05

    Photochemical degradation of dissolved organic matter (DOM) to carbon dioxide (CO2) and partially oxidized compounds is an important component of the carbon cycle in the Arctic. Thawing permafrost soils will change the chemical composition of DOM exported to arctic surface waters, but the molecular controls on DOM photodegradation remain poorly understood, making it difficult to predict how inputs of thawing permafrost DOM may alter its photodegradation. To address this knowledge gap, we quantified the susceptibility of DOM draining the shallow organic mat and the deeper permafrost layer of arctic soils to complete and partial photo-oxidation and investigated changes in the chemical composition of each DOM source following sunlight exposure. Permafrost and organic mat DOM had similar lability to photomineralization despite substantial differences in initial chemical composition. Concurrent losses of carboxyl moieties and shifts in chemical composition during photodegradation indicated that photodecarboxylation could account for 40-90% of DOM photomineralized to CO2. Permafrost DOM had a higher susceptibility to partial photo-oxidation compared to organic mat DOM, potentially due to a lower abundance of phenolic moieties with antioxidant properties. These results suggest that photodegradation will likely continue to be an important control on DOM fate in arctic freshwaters as the climate warms and permafrost soils thaw.

  11. Soil organic (14)C dynamics : Effects of pasture installation on arable land

    NARCIS (Netherlands)

    Romkens, P.F A M; Hassink, J; van der Plicht, Johannes

    1998-01-01

    In a study addressing composition and recovery of soil carbon following pasture installation on arable land, radiocarbon isotope ratios were measured in size- and density-separated soil organic matter (SOM) fractions in a pasture and maize plot. The average soil carbon age increased with depth from

  12. Soil organic 14C dynamics: effects of pasture installation on arable land

    NARCIS (Netherlands)

    Römkens, P.F.A.M.; Plicht, van der J.; Hassink, J.

    1998-01-01

    In a study addressing composition and recovery of soil carbon following pasture installation on arable land, radiocarbon isotope ratios were measured in size-and density-separated soil organic matter (SOM) fractions in a pasture and maize plot. The average soil carbon age increased with depth from

  13. [Microscopic soil fungi - bioindicators organisms contaminated soil].

    Science.gov (United States)

    Donerian, L G; Vodianova, M A; Tarasova, Zh E

    In the paper there are considered methodological issues for the evaluation of soil biota in terms of oil pollution. Experimental studies have shown that under the exposure of a various levels of oil pollution meeting certain gradations of the state and optimal alteration in microbocenosis in sod-podzolic soils, there is occurred a transformation of structure of the complex of micromycetes and the accumulation of toxic species, hardly typical for podzolic soils - primarily represantatives of the genus Aspergillus (A.niger and A. versicolor), Paecilomyces (P.variotii Bainer), Trichoderma (T.hamatum), the genus of phytopathogens Fusarium (F.oxysporum), dermatophytes of genus Sporothrix (S. schenckii) and dark-colored melanin containing fungi of Dematiaceae family. Besides that there are presented data on the study of microbiocenosis of the urban soil, the urban soil differed from the zone soil, but shaped in similar landscape and climatic conditions, and therefore having a tendency to a similar response from the side of microorganisms inhabiting the soil. Isolated complex of soil microscopic fungi is described by many authors as a complex, characteristic for soils of megalopolises. This allowed authors of this work to suggest that in urban soils the gain in the occurrence of pathogenic species micromycetes also increases against a background of chronic, continuously renewed inflow of petroleum hydrocarbons from various sources of pollution. Because changes in the species composition of micromycetes occurred in accordance with the increasing load of oil, so far as microscopic soil fungi can be recommended as a bioindicator organisms for oil. In the article there is also provided information about the distinctive features of modern DNA identification method of soil microscopic fungi and accepted in our country methodology of isolation of micromycetes with the use of a nutrient Czapek medium.

  14. Soil Decomposition of Added Organic C in an Organic Farming System

    Science.gov (United States)

    Kpomblekou-A, Kokoasse; Sissoko, Alassane; McElhenney, Wendell

    2015-04-01

    In the United States, large quantities of poultry waste are added every year to soil under organic management. Decomposition of the added organic C releases plant nutrients, promotes soil structure, and plays a vital role in the soil food web. In organic agriculture the added C serves as the only source of nutrients for plant growth. Thus understanding the decomposition rates of such C in organic farming systems are critical in making recommendations of organic inputs to organic producers. We investigated and compared relative accumulation and decomposition of organic C in an organic farming system trial at the George Washington Carver Agricultural Experiment Station at Tuskegee, Alabama on a Marvyn sandy loam (fine-loamy, kaolinitic, thermic, Typic Kanhapludults) soil. The experimental design was a randomized complete block with four replicates and four treatments. The main plot (54' × 20') was split into three equal subplots to plant three sweet potato cultivars. The treatments included a weed (control with no cover crop, no fertilizer), crimson clover alone (CC), crimson clover plus broiler litter (BL), and crimson clover plus NPK mineral fertilizers (NPK). For five years, late in fall, the field was planted with crimson clover (Trifolium incarnatum L) that was cut with a mower and incorporated into soil the following spring. Moreover, broiler litter (4.65 Mg ha-1) or ammonium nitrate (150 kg N ha-1), triple super phosphate (120 kg P2O5 ha-1), and potassium chloride (160 kg K2O ha-1) were applied to the BL or the NPK plot and planted with sweet potato. Just before harvest, six soil samples were collected within the two middle rows of each sweet potato plot with an auger at incremental depths of 0-1, 1-2, 2-3, 3-5, 5-10, and 10-15 cm. Samples from each subplot and depth were composited and mixed in a plastic bag. The samples were sieved moist through a

  15. Soil biodiversity and soil community composition determine ecosystem multifunctionality

    Science.gov (United States)

    Wagg, Cameron; Bender, S. Franz; Widmer, Franco; van der Heijden, Marcel G. A.

    2014-01-01

    Biodiversity loss has become a global concern as evidence accumulates that it will negatively affect ecosystem services on which society depends. So far, most studies have focused on the ecological consequences of above-ground biodiversity loss; yet a large part of Earth’s biodiversity is literally hidden below ground. Whether reductions of biodiversity in soil communities below ground have consequences for the overall performance of an ecosystem remains unresolved. It is important to investigate this in view of recent observations that soil biodiversity is declining and that soil communities are changing upon land use intensification. We established soil communities differing in composition and diversity and tested their impact on eight ecosystem functions in model grassland communities. We show that soil biodiversity loss and simplification of soil community composition impair multiple ecosystem functions, including plant diversity, decomposition, nutrient retention, and nutrient cycling. The average response of all measured ecosystem functions (ecosystem multifunctionality) exhibited a strong positive linear relationship to indicators of soil biodiversity, suggesting that soil community composition is a key factor in regulating ecosystem functioning. Our results indicate that changes in soil communities and the loss of soil biodiversity threaten ecosystem multifunctionality and sustainability. PMID:24639507

  16. Structure of bacterial communities in soil following cover crop and organic fertilizer incorporation.

    Science.gov (United States)

    Fernandez, Adria L; Sheaffer, Craig C; Wyse, Donald L; Staley, Christopher; Gould, Trevor J; Sadowsky, Michael J

    2016-11-01

    Incorporation of organic material into soils is an important element of organic farming practices that can affect the composition of the soil bacterial communities that carry out nutrient cycling and other functions crucial to crop health and growth. We conducted a field experiment to determine the effects of cover crops and fertilizers on bacterial community structure in agricultural soils under long-term organic management. Illumina sequencing of 16S rDNA revealed diverse communities comprising 45 bacterial phyla in corn rhizosphere and bulk field soil. Community structure was most affected by location and by the rhizosphere effect, followed by sampling time and amendment treatment. These effects were associated with soil physicochemical properties, including pH, moisture, organic matter, and nutrient levels. Treatment differences were apparent in bulk and rhizosphere soils at the time of peak corn growth in the season following cover crop and fertilizer application. Cover crop and fertilizer treatments tended to lower alpha diversity in early season samples. However, winter rye, oilseed radish, and buckwheat cover crop treatments increased alpha diversity in some later season samples compared to a no-amendment control. Fertilizer treatments and some cover crops decreased relative abundance of members of the ammonia-oxidizing family Nitrosomonadaceae. Pelleted poultry manure and Sustane® (a commercial fertilizer) decreased the relative abundance of Rhizobiales. Our data point to a need for future research exploring how (1) cover crops influence bacterial community structure and functions, (2) these effects differ with biomass composition and quantity, and (3) existing soil conditions and microbial community composition influence how soil microbial populations respond to agricultural management practices.

  17. Biomimetic Hydrogel Composites for Soil Stabilization and Contaminant Mitigation.

    Science.gov (United States)

    Zhao, Zhi; Hamdan, Nasser; Shen, Li; Nan, Hanqing; Almajed, Abdullah; Kavazanjian, Edward; He, Ximin

    2016-11-15

    We have developed a novel method to synthesize a hyper-branched biomimetic hydrogel network across a soil matrix to improve the mechanical strength of the loose soil and simultaneously mitigate potential contamination due to excessive ammonium. This method successfully yielded a hierarchical structure that possesses the water retention, ion absorption, and soil aggregation capabilities of plant root systems in a chemically controllable manner. Inspired by the robust organic-inorganic composites found in many living organisms, we have combined this hydrogel network with a calcite biomineralization process to stabilize soil. Our experiments demonstrate that poly(acrylic acid) (PAA) can work synergistically with enzyme-induced carbonate precipitation (EICP) to render a versatile, high-performance soil stabilization method. PAA-enhanced EICP provides multiple benefits including lengthening of water supply time, localization of cementation reactions, reduction of harmful byproduct ammonium, and achievement of ultrahigh soil strength. Soil crusts we have obtained can sustain up to 4.8 × 10 3 kPa pressure, a level comparable to cementitious materials. An ammonium removal rate of 96% has also been achieved. These results demonstrate the potential for hydrogel-assisted EICP to provide effective soil improvement and ammonium mitigation for wind erosion control and other applications.

  18. Compositional differences in simulated root exudates elicit a limited functional and compositional response in soil microbial communities

    Directory of Open Access Journals (Sweden)

    Michael S Strickland

    2015-08-01

    Full Text Available Inputs of low molecular weight carbon (LMW-C to soil −primarily via root exudates− are expected to be a major driver of microbial activity and source of stable soil organic carbon. It is expected that variation in the type and composition of LMW-C entering soil will influence microbial community composition and function. If this is the case then short-term changes in LMW-C inputs may alter processes regulated by these communities. To determine if change in the composition of LMW-C inputs influences microbial community function and composition, we conducted a 90 day microcosm experiment whereby soils sourced from three different land covers (meadows, deciduous forests, and white pine stands were amended, at low concentrations, with one of eight simulated root exudate treatments. Treatments included no addition of LMW-C, and the full factorial combination of glucose, glycine, and oxalic acid. After 90 days, we conducted a functional response assay and determined microbial composition via phospholipid fatty acid analysis. Whereas we noted a statistically significant effect of exudate treatments, this only accounted for ~3% of the variation observed in function. In comparison, land cover and site explained ~46 and ~41% of the variation, respectively. This suggests that exudate composition has little influence on function

  19. Chemical-Structural Changes of Organic Matter in a Semi-Arid Soil After Organic Amendment

    Institute of Scientific and Technical Information of China (English)

    C.NICOL(A)S; G.MASCIANDARO; T.HERN(A)NDEZ; C.GARCIA

    2012-01-01

    A 9-month incubation experiment using composted and non-composted amendments derived from vine pruning waste and sewage sludge was carried out to study the effects of the nature and stability of organic amendments on the structural composition of organic matter (OM) in a semi-arid soil. The changes of soil OM,both in the whole soil and in the extractable carbon with pyrophosphate,were evaluated by pyrolysis-gas chromatography and chemical analyses.By the end of the experiment,the soils amended with pruning waste exhibited less organic carbon loss than those receiving sewage sludge.The non-composted residues increased the aliphatic-pyrolytic products of the OM,both in the whole soil and also in the pyrophosphate extract,with the products derived from peptides and proteins being significantly higher.After 9 months,in the soils amended with pruning waste the relative abundance of phenolic-pyrolytic products derived from phenolic compounds,lignin and proteins in the whole soil tended to increase more than those in the soils amended with sewage sludge.However,the extractable OM with pyrophosphate in the soils amended with composted residues tended to have higher contents of these phenolic-pyrolytic products than that in non-composted ones.Thus,despite the stability of pruning waste,the composting of this material promoted the incorporation of phenolic compounds to the soil OM.The pyrolytic indices (furfural/pyrrole and aliphatic/aromatic ratios) showed the diminution of aliphatic compounds and the increase of aromatic compounds,indicating the stabilization of the OM in the amended soils after 9 months.In conclusion,the changes of soil OM depend on the nature and stability of the organic amendments,with composted vine pruning waste favouring humification.

  20. Chemical composition and Zn bioavailability of the soil solution extracted from Zn amended variable charge soils.

    Science.gov (United States)

    Zampella, Mariavittoria; Adamo, Paola

    2010-01-01

    A study on variable charge soils (volcanic Italian and podzolic Scottish soils) was performed to investigate the influence of soil properties on the chemical composition of soil solution. Zinc speciation, bioavailability and toxicity in the soil solution were examined. The soils were spiked with increasing amounts of Zn (0, 100, 200, 400 and 1000 mg/kg) and the soil solutions were extracted using rhizon soil moisture samplers. The pH, total organic carbon (TOC), base cations, anions, total Zn and free Zn2+ in soil solution were analysed. A rapid bioassay with the luminescent bacterium Escherichia coli HB101 pUCD607 was performed to assess Zn toxicity. The influence of soil type and Zn treatments on the chemical composition of soil solution and on Zn toxicity was considered and discussed. Different trends of total and free Zn concentrations, base cations desorption and luminescence of E. coli HB101 pUCD607 were observed. The soil solution extracted from the volcanic soils had very low total and free Zn concentrations and showed specific Zn2+/Ca2+ exchange. The soil solution from the podzolic soil had much higher total and free Zn concentrations and showed no evidence of specific Zn2+/Ca2+ exchange. In comparison with the subalkaline volcanic soils, the acidic podzol showed enhanced levels of toxic free Zn2+ and consequently stronger effects on E. coli viability.

  1. Measurements of flux and isotopic composition of soil carbon dioxide

    International Nuclear Information System (INIS)

    Gorczyca, Z.; Rozanski, K.; Kuc, T.

    2002-01-01

    The flux and isotope composition of soil CO 2 has been regularly measured at three sites located in the southern Poland, during the time period: January 1998 - October 2000. They represent typical ecosystems appearing in central Europe: (i) mixed forest; (ii) cultivated agricultural field; (iii) grassland. To monitor the flux and isotopic composition of soil CO 2 , a method based on the inverted cup principle was adopted. The flux of soil CO 2 reveals distinct seasonal fluctuations, with maximum values up to ca. 25 mmol/m 2 /h during sommer months and around ten times lower values during winter time. Also significant differences among the monitored sites were detected, the flux density of this gas being highest for the mixed forest site and ca. two times lower for the cultivated grassland. Carbon-13 content of the soil CO 2 reveals little seasonal variability, with δ 13 C values essentially reflecting the isotopic composition of the soil organic matter and the vegetation type. The carbon-14 content of soil CO 2 flux also reveals slight seasonality, with lower δ 14 C values recorded during winter time. Significantly lower δ 14 C values recorded during winter time. Significantly lower δ 14 C values were recorded at depth. (author)

  2. Forms of organic phosphorus in wetland soils

    Science.gov (United States)

    Cheesman, A. W.; Turner, B. L.; Reddy, K. R.

    2014-12-01

    Phosphorus (P) cycling in freshwater wetlands is dominated by biological mechanisms, yet there has been no comprehensive examination of the forms of biogenic P (i.e., forms derived from biological activity) in wetland soils. We used solution 31P NMR spectroscopy to identify and quantify P forms in surface soils of 28 palustrine wetlands spanning a range of climatic, hydrogeomorphic, and vegetation types. Total P concentrations ranged between 51 and 3516 μg P g-1, of which an average of 58% was extracted in a single-step NaOH-EDTA procedure. The extracts contained a broad range of P forms, including phosphomonoesters (averaging 24% of the total soil P), phosphodiesters (averaging 10% of total P), phosphonates (up to 4% of total P), and both pyrophosphate and long-chain polyphosphates (together averaging 6% of total P). Soil P composition was found to be dependant upon two key biogeochemical properties: organic matter content and pH. For example, stereoisomers of inositol hexakisphosphate were detected exclusively in acidic soils with high mineral content, while phosphonates were detected in soils from a broad range of vegetation and hydrogeomorphic types but only under acidic conditions. Conversely inorganic polyphosphates occurred in a broad range of wetland soils, and their abundance appears to reflect more broadly that of a "substantial" and presumably active microbial community with a significant relationship between total inorganic polyphosphates and microbial biomass P. We conclude that soil P composition varies markedly among freshwater wetlands but can be predicted by fundamental soil properties.

  3. Chemical compositions and sources of organic matter in fine particles of soils and sands from the vicinity of Kuwait city.

    Science.gov (United States)

    Rushdi, Ahmed I; Al-Zarban, Sheikha; Simoneit, Bernd R T

    2006-09-01

    Fine particles in the atmosphere from soil and sand resuspension contain a variety of organic compounds from natural biogenic and anthropogenic matter. Soil and sand samples from various sites near Kuwait city were collected, sieved to retain the fine particles, and extracted with a mixture of dichloromethane and methanol. The extracts were derivatized and analyzed by gas chromatography-mass spectrometry in order to characterize the chemical compositions and sources of the organic components. The major inputs of organic compounds were from both natural biogenic and anthropogenic sources in these samples. Vegetation was the major natural source of organic compounds and included n-alkanols, n-alkanoic acids, n-alkanes, sterols and triterpenoids. Saccharides had high concentrations (31-43%) in the sand dune and seafront samples, indicating sources from decomposed vegation materials and/or the presence of viable microbiota such as bacteria and fungi. Vehicular emission products, leakage of lubricating oils, discarded plastics and emissions from cooking operations were the major anthropogenic inputs in the samples from the urban areas. This input was mainly UCM, n-alkanes, hopanes, plasticizers and cholesterol, respectively.

  4. Physical and chemical protection of soil organic carbon in three agricultural soils with different contents of calcium carbonate

    International Nuclear Information System (INIS)

    Clough, A.; Skjemstad, J.O.

    2000-01-01

    The amount of organic carbon physically protected by entrapment within aggregates and through polyvalent cation organic matter bridging was determined on non-calcareous and calcareous soils. The composition of organic carbon in whole soils and 13 C NMR analysis. High energy photo-oxidation was carried out on <53 μm fractions and results from the NMR spectra showed 17-40% of organic carbon was in a condensed aromatic form, most likely charcoal (char). The concept that organic material remaining after photo-oxidation may be physically protected within aggregates was investigated by treating soils with a mild acid prior to photo-oxidation. More organic material was protected in the calcareous than the non-calcareous soils, regardless of whether the calcium occurred naturally or was an amendment. Acid treatment indicated that the presence of exchangeable calcium reduced losses of organic material upon photo-oxidation by about 7% due to calcium bridging. These results have implications for N fertiliser recommendations based upon organic carbon content. Firstly, calcium does not impact upon degradability of organic material to an extent likely to affect N fertiliser recommendations. Secondly, standard assessment techniques overestimate active organic carbon content in soils with high char content. Copyright (2000) CSIRO Publishing

  5. Bacterial diversity and composition in major fresh produce growing soils affected by physiochemical properties and geographic locations

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Jincai [Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021 (China); USDA-ARS U. S. Salinity Laboratory, Riverside, CA 92507 (United States); Ibekwe, A. Mark, E-mail: Mark.Ibekwe@ars.usda.gov [USDA-ARS U. S. Salinity Laboratory, Riverside, CA 92507 (United States); Yang, Ching-Hong [Department of Biological Sciences, University of Wisconsin, Milwaukee, WI 53211 (United States); Crowley, David E. [Department of Environmental Sciences, University of California, Riverside, CA 92521 (United States)

    2016-09-01

    Microbial diversity of agricultural soils has been well documented, but information on leafy green producing soils is limited. In this study, we investigated microbial diversity and community structures in 32 (16 organic, 16 conventionally managed soils) from California (CA) and Arizona (AZ) using pyrosequencing, and identified factors affecting bacterial composition. Results of detrended correspondence analysis (DCA) and dissimilarity analysis showed that bacterial community structures of conventionally managed soils were similar to that of organically managed soils; while the bacterial community structures in soils from Salinas, California were different (P < 0.05) from those in soils from Yuma, Arizona and Imperial Valley, California. Canonical correspondence analysis (CCA) and artificial neural network (ANN) analysis of bacterial community structures and soil variables showed that electrical conductivity (EC), clay content, water-holding capacity (WHC), pH, total nitrogen (TN), and organic carbon (OC) significantly (P < 0.05) correlated with microbial communities. CCA based variation partitioning analysis (VPA) showed that soil physical properties (clay, EC, and WHC), soil chemical variables (pH, TN, and OC) and sampling location explained 16.3%, 12.5%, and 50.9%, respectively, of total variations in bacterial community structure, leaving 13% of the total variation unexplained. Our current study showed that bacterial community composition and diversity in major fresh produce growing soils from California and Arizona is a function of soil physiochemical characteristics and geographic distances of sampling sites. - Highlights: • Geographic distance was the most significant factor affecting microbial composition. • Physical and chemical properties significantly impacted microbial communities. • Higher numbers of OTUs were observed in organic soils than in convention soils.

  6. Bacterial diversity and composition in major fresh produce growing soils affected by physiochemical properties and geographic locations

    International Nuclear Information System (INIS)

    Ma, Jincai; Ibekwe, A. Mark; Yang, Ching-Hong; Crowley, David E.

    2016-01-01

    Microbial diversity of agricultural soils has been well documented, but information on leafy green producing soils is limited. In this study, we investigated microbial diversity and community structures in 32 (16 organic, 16 conventionally managed soils) from California (CA) and Arizona (AZ) using pyrosequencing, and identified factors affecting bacterial composition. Results of detrended correspondence analysis (DCA) and dissimilarity analysis showed that bacterial community structures of conventionally managed soils were similar to that of organically managed soils; while the bacterial community structures in soils from Salinas, California were different (P < 0.05) from those in soils from Yuma, Arizona and Imperial Valley, California. Canonical correspondence analysis (CCA) and artificial neural network (ANN) analysis of bacterial community structures and soil variables showed that electrical conductivity (EC), clay content, water-holding capacity (WHC), pH, total nitrogen (TN), and organic carbon (OC) significantly (P < 0.05) correlated with microbial communities. CCA based variation partitioning analysis (VPA) showed that soil physical properties (clay, EC, and WHC), soil chemical variables (pH, TN, and OC) and sampling location explained 16.3%, 12.5%, and 50.9%, respectively, of total variations in bacterial community structure, leaving 13% of the total variation unexplained. Our current study showed that bacterial community composition and diversity in major fresh produce growing soils from California and Arizona is a function of soil physiochemical characteristics and geographic distances of sampling sites. - Highlights: • Geographic distance was the most significant factor affecting microbial composition. • Physical and chemical properties significantly impacted microbial communities. • Higher numbers of OTUs were observed in organic soils than in convention soils

  7. Influence of management on the composition of organic matter in a red-brown earth as shown by 13C nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Oades, J.M.; Waters, A.G.; Jones, G.P.; Vassallo, A.M.; Wilson, M.A.

    1988-01-01

    Samples were obtained from the same red-brown earth: in an undisturbed state, after 60 years of an exploitive wheat-fallow rotation and after 40 years under a fertilized mixed grass-legume pasture. Organic materials were concentrated in various fractions which enabled comparative chemical composition of the organic materials in the three soils by 13 C CPMAS n.m.r. spectroscopy. Despite more than twofold differences in the organic carbon content of the soils, the chemistry of the organic matter in the soils was similar, particularly organic matter associated with clay fractions. Most of the differences detected were associated with plant debris in particles > 20 μm which contained most of the aromatic carbon. The results indicate a rapid disappearance of phenolic-carbon which originates in lignins. The composition of sodium hydroxide extracts reflects quite well the composition of the organic matter in the soil. It is concluded that in a particulate soil type, changes in amount and nature of added photosynthate do not change the composition of the organic matter which is controlled by the microbial biomass and interactions of the biomass and its decomposition products with the soil matrix. Implications of this conclusion for the turnover of organic carbon in soil and stability of soil structure are discussed. 20 refs., 4 figs

  8. The role of soil biogeochemistry in wine taste: Soil factors influencing grape elemental composition, photosynthetic biomarkers and Cu/Zn isotopic signature of Vitis vinifera

    Science.gov (United States)

    Blotevogel, Simon; Oliva, Priscia; Darrozes, José; Viers, Jérôme; Audry, Stéphane; Courjault-Radé, Pierre; Orgogozo, Laurent; Le Guedard, Marina; Schreck, Eva

    2015-04-01

    to the geological difference. These soils differ in elemental compositions and bioavailability of mineral nutrients, preconditions for a potential influence on plants and wine. Elemental ratios of soils are partly transmitted to leaves and grapes of correspondent plants, including nutrients such as Ca. Plant photosynthetic functioning is significantly better on the limestone vineyard due to lower Cu bioavailability: Omega-3 values are negatively linked to Cu bioavailability in corresponding soils. These observations suggest a difference in organic molecule synthesis depending on the vineyard soil, which might include components relevant for taste and fermentation. Cu and Zn isotopic ratios do not differ between both soils. The main fractionation of Cu and Zn isotopes occurs at the soil-plant interface making those isotopes suitable tracers for uptake mechanisms. As a result Zn isotope ratios reveal a strong recycling of Zn in the soil-plant continuum. Our results show a significant influence of soil composition on grape composition, plant biochemistry and potentially wine taste. Determination of organic and sensorial composition of grapes and wine is ongoing and will be discussed in further communications.

  9. Impact of tree cutting on water-soluble organic compounds in podzolic soils of the European North-East

    Science.gov (United States)

    Lapteva, Elena; Bondarenko, Natalia; Shamrikova, Elena; Kubik, Olesya; Punegov, Vasili

    2016-04-01

    Water-soluble organic compounds (WOCs) and their single components, i.e. low-molecular organic acids, alcohols, and carbohydrates, attain a great deal of attention among soil scientists. WOCs are an important component of soil organic matter (SOM) and form as a results of different biological and chemical processes in soils. These processes are mainly responsible for formation and development of soils in aboveground ecosystems. The purpose of the work was identifying qualitative and quantitative composition of low-molecular organic substances which form in podzolic loamy soils against natural reforestation after spruce forest cutting. The studies were conducted on the territory of the European North-East of Russia, in the middle taiga subzone (Komi Republic, Ust-Kulom region). The study materials were soil of undisturbed bilberry spruce forest (Sample Plot 1 (SP1)) and soils of different-aged tree stands where cutting activities took place in winter 2001/2002 (SP2) and 1969/1970 (SP3). Description of soils and vegetation cover on the plots is given in [1]. Low-molecular organic compounds in soil water extracts were identified by the method of gas chromatography mass-spectrometry [2, 3]. Finally, reforestationafterspruceforestcutting was found to be accompanied by different changes in soil chemical composition. In contrast with soils under undisturbed spruce forest, organic soil horizons under different-aged cuts decreased in organic carbon reserves and production of low-molecular organic compounds, changed in soil acidity. Within the soil series of SP1→SP2→SP3, the highest content of WOCs was identified for undisturbed spruce forest (738 mg kg-1 soil). In soils of coniferous-deciduous forests on SP1 and SP3, WOC content was 294 and 441 mg kg-1 soil, correspondingly. Soils at cuts decreased in concentration of any water-soluble low-molecular SOM components as low-molecular acids, alcohols, and carbohydrates. Structure of low-molecular WOCs in the study podzolic

  10. Compositional differences in simulated root exudates elicit a limited functional and compositional response in soil microbial communities.

    Science.gov (United States)

    Strickland, Michael S; McCulley, Rebecca L; Nelson, Jim A; Bradford, Mark A

    2015-01-01

    Inputs of low molecular weight carbon (LMW-C) to soil - primarily via root exudates- are expected to be a major driver of microbial activity and source of stable soil organic carbon. It is expected that variation in the type and composition of LMW-C entering soil will influence microbial community composition and function. If this is the case then short-term changes in LMW-C inputs may alter processes regulated by these communities. To determine if change in the composition of LMW-C inputs influences microbial community function and composition, we conducted a 90 day microcosm experiment whereby soils sourced from three different land covers (meadows, deciduous forests, and white pine stands) were amended, at low concentrations, with one of eight simulated root exudate treatments. Treatments included no addition of LMW-C, and the full factorial combination of glucose, glycine, and oxalic acid. After 90 days, we conducted a functional response assay and determined microbial composition via phospholipid fatty acid analysis. Whereas we noted a statistically significant effect of exudate treatments, this only accounted for ∼3% of the variation observed in function. In comparison, land cover and site explained ∼46 and ∼41% of the variation, respectively. This suggests that exudate composition has little influence on function compared to site/land cover specific factors. Supporting the finding that exudate effects were minor, we found that an absence of LMW-C elicited the greatest difference in function compared to those treatments receiving any LMW-C. Additionally, exudate treatments did not alter microbial community composition and observable differences were instead due to land cover. These results confirm the strong effects of land cover/site legacies on soil microbial communities. In contrast, short-term changes in exudate composition, at meaningful concentrations, may have little impact on microbial function and composition.

  11. Using saturation water percentage data to predict mechanical composition of soils

    International Nuclear Information System (INIS)

    Mbagwu, J.S.C.; Okafor, D.O.

    1995-04-01

    One hundred and sixty-six soil samples representing eleven textural classes and having wide variations in organic matter (OM) contents and other physico-chemical properties were collected from different locations in southeastern Nigeria to study the relationship between mechanical composition and saturation water percentage (SP). The objective was to develop a prediction model for silt + clay (SC) and clay (C) contents of these soils using the SP values. The magnitude of the correlation coefficients (r) between SC or C and SP was dependent on the amount of organic matter (OM) present in the soils. For soils with ≤ 1.00% OM, the correlation (r) between SC and SP was 0.9659 (p ≤ 0.001) and that between C and SP was 0.9539 (p ≤ 0.001). For soils with ≥ 2.00% OM, the 'r' values were generally low, varying between 0.5320 and 0.2665 for SC and 0.6008 and 0.3000 for C. The best-fit regression models for predicting SC and C were developed with soils having ≤ 1.00% OM. An independent data set from 25 soil samples collected from other parts of the study area was used to test the predictive ability of the best-fit models. These models predicted SC and C accurately in soils having between 0.28 and 1.10% OM, but poorly in soils having between 1.31 and 3.91% OM. These results show that the use of saturation water percentage to predict the mechanical composition of soils is most reliable for soils with low (≤ 1.00%) OM contents. (author). 18 refs, 2 figs, 5 tabs

  12. Response of organic matter quality in permafrost soils to warming

    Science.gov (United States)

    Plaza, C.; Pegoraro, E.; Schuur, E.

    2016-12-01

    Global warming is predicted to thaw large quantities of the perennially frozen organic matter stored in northern permafrost soils. Upon thaw, this organic matter will be exposed to lateral export to water bodies and to microbial decomposition, which may exacerbate climate change by releasing significant amounts of greenhouse gases. To gain an insight into these processes, we investigated how the quality of permafrost soil organic matter responded to five years of warming. In particular, we sampled control and experimentally warmed soils in 2009 and 2013 from an experiment established in 2008 in a moist acidic tundra ecosystem in Healy, Alaska. We examined surface organic (0 to 15 cm), deep organic (15 to 35 cm), and mineral soil layers (35 to 55 cm) separately by means of stable isotope analysis (δ13C and δ15N) and solid-state 13C nuclear magnetic resonance. Compared to the control, the experimental warming did not affect the isotopic and molecular composition of soil organic matter across the depth profile. However, we did find significant changes with time. In particular, in the surface organic layer, δ13C decreased and alkyl/O-alkyl ratio increased from 2009 to 2013, which indicated variations in soil organic sources (e.g., changes in vegetation) and accelerated decomposition. In the deep organic layer, we found a slight increase in δ15N with time. In the mineral layer, δ13C values decreased slightly, whereas alkyl C/O-alkyl ratio increased, suggesting a preferential loss of relatively more degraded organic matter fractions probably by lateral transport by water flowing through the soil. Acknowledgements: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 654132. Web site: http://vulcan.comule.com

  13. Physico-chemical protection, rather than biochemical composition, governs the responses of soil organic carbon decomposition to nitrogen addition in a temperate agroecosystem.

    Science.gov (United States)

    Tan, Wenbing; Wang, Guoan; Huang, Caihong; Gao, Rutai; Xi, Beidou; Zhu, Biao

    2017-11-15

    The heterogeneous responses of soil organic carbon (SOC) decomposition in different soil fractions to nitrogen (N) addition remain elusive. In this study, turnover rates of SOC in different aggregate fractions were quantified based on changes in δ 13 C following the conversion of C 3 to C 4 vegetation in a temperate agroecosystem. The turnover of both total organic matter and specific organic compound classes within each aggregate fraction was inhibited by N addition. Moreover, the intensity of inhibition increases with decreasing aggregate size and increasing N addition level, but does not vary among chemical compound classes within each aggregate fraction. Overall, the response of SOC decomposition to N addition is dependent on the physico-chemical protection of SOC by aggregates and minerals, rather than the biochemical composition of organic substrates. The results of this study could help to understand the fate of SOC in the context of increasing N deposition. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Soil organic carbon dynamics jointly controlled by climate, carbon inputs, soil properties and soil carbon fractions.

    Science.gov (United States)

    Luo, Zhongkui; Feng, Wenting; Luo, Yiqi; Baldock, Jeff; Wang, Enli

    2017-10-01

    Soil organic carbon (SOC) dynamics are regulated by the complex interplay of climatic, edaphic and biotic conditions. However, the interrelation of SOC and these drivers and their potential connection networks are rarely assessed quantitatively. Using observations of SOC dynamics with detailed soil properties from 90 field trials at 28 sites under different agroecosystems across the Australian cropping regions, we investigated the direct and indirect effects of climate, soil properties, carbon (C) inputs and soil C pools (a total of 17 variables) on SOC change rate (r C , Mg C ha -1  yr -1 ). Among these variables, we found that the most influential variables on r C were the average C input amount and annual precipitation, and the total SOC stock at the beginning of the trials. Overall, C inputs (including C input amount and pasture frequency in the crop rotation system) accounted for 27% of the relative influence on r C , followed by climate 25% (including precipitation and temperature), soil C pools 24% (including pool size and composition) and soil properties (such as cation exchange capacity, clay content, bulk density) 24%. Path analysis identified a network of intercorrelations of climate, soil properties, C inputs and soil C pools in determining r C . The direct correlation of r C with climate was significantly weakened if removing the effects of soil properties and C pools, and vice versa. These results reveal the relative importance of climate, soil properties, C inputs and C pools and their complex interconnections in regulating SOC dynamics. Ignorance of the impact of changes in soil properties, C pool composition and C input (quantity and quality) on SOC dynamics is likely one of the main sources of uncertainty in SOC predictions from the process-based SOC models. © 2017 John Wiley & Sons Ltd.

  15. Comparing molecular composition of dissolved organic matter in soil and stream water: Influence of land use and chemical characteristics.

    Science.gov (United States)

    Seifert, Anne-Gret; Roth, Vanessa-Nina; Dittmar, Thorsten; Gleixner, Gerd; Breuer, Lutz; Houska, Tobias; Marxsen, Jürgen

    2016-11-15

    Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) was used to examine the molecular composition of dissolved organic matter (DOM) from soils under different land use regimes and how the DOM composition in the catchment is reflected in adjacent streams. The study was carried out in a small area of the Schwingbach catchment, an anthropogenic-influenced landscape in central Germany. We investigated 30 different soil water samples from 4 sites and different depths (managed meadow (0-5cm, 40-50cm), deciduous forest (0-5cm), mixed-coniferous forest (0-5cm) and agricultural land (0-5cm, 40-50cm)) and 8 stream samples. 6194 molecular formulae and their magnitude-weighted parameters ((O/C)w, (H/C)w, (N/C)w, (AI-mod)w, (DBE/C)w, (DBE/O)w, (DBE-O)w, (C#)w, (MW)w) were used to describe the molecular composition of the samples. The samples can be roughly divided in three groups. Group 1 contains samples from managed meadow 40-50cm and stream water, which are characterized by high saturation compared to samples from group 2 including agricultural samples and samples from the surface meadow (0-5cm), which held more nitrogen containing and aromatic compounds. Samples from both forested sites (group 3) are characterized by higher molecular weight and O/C ratio. Environmental parameters vary between sites and among these parameters pH and nitrate significantly affect chemical composition of DOM. Results indicate that most DOM in streams is of terrestrial origin. However, 120 molecular formulae were detected only in streams and not in any of the soil samples. These compounds share molecular formulae with peptides, unsaturated aliphatics and saturated FA-CHO/FA-CHOX. Compounds only found in soil samples are much more aromatic, have more double bonds and a much lower H/C ratio but higher oxygen content, which indicates the availability of fresh plant material and less microbial processed material compared to stream samples. Copyright

  16. Physical and Human Controls on the Carbon Composition of Organic Matter in Tropical Rivers: An Integrated Analysis of Landscape Properties and River Isotopic Composition

    Energy Technology Data Exchange (ETDEWEB)

    Ballester, M. V.R.; Victoria, R. L.; Krusche, A. V. [Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, Piracicaba (Brazil); Bernardes, M. [Universidade Federal Fluminense, Rio de Janeiro (Brazil); Neill, C.; Deegan, L. [Marine Biological Laboratory, Woods Hole, MA (United States); Richey, J. E. [University of Washington, Seatle, WA (United States)

    2013-05-15

    We applied an integrated analysis of landscape properties including soil properties, land cover and riverine isotopic composition. To evaluate physical and human controls on the carbon composition of organic matter in tropical rivers, we applied an integrated analysis of landscape properties including soil properties, land cover and riverine isotopic composition. Our main objective was to establish the relationship between basin attributes and forms, fluxes and composition of dissolved and particulate organic matter in river channels. A physical template was developed as a GIS-based comprehensive tool to support the understanding of the biogeochemistry of the surface waters of two tropical rivers: the Ji-Parana (Western Amazonia) and the Piracicaba (southeastern of Brazil). For each river we divided the basin into drainage units, organized according to river network morphology and degree of land use impact. Each sector corresponded to a sampling point where river isotopic composition was analysed. River sites and basin characteristics were calculated using datasets compiled as layers in ArcGis Geographical Information System and ERDAS-IMAGINE (Image Processing) software. Each delineated drainage area was individually characterized in terms of topography, soils, river network and land use. Carbon stable isotopic composition of dissolved organic matter (DOM) and particulate organic matter (POM) was determined at several sites along the main tributaries and small streams. The effects of land use on fluvial carbon composition were quantified by a linear regression analysis, relating basin cover and river isotopic composition. The results showed that relatively recent land cover changes have already had an impact on the composition of the riverine DOM and POM, indicating that, as in natural ecosystems, vegetation plays a key role in the composition of riverine organic matter in agricultural ecosystems. (author)

  17. Microbial activity and soil organic matter decay in roadside soils polluted with petroleum hydrocarbons

    Science.gov (United States)

    Mykhailova, Larysa; Fischer, Thomas; Iurchenko, Valentina

    2015-04-01

    positively correlated with the carbohydrate fraction and negatively correlated with the aliphatic fraction of the soil C, while carbohydrate-C and alkyl-C increased and decreased with distance from the road, respectively. It is proposed that petroleum hydrocarbons supress soil biological activity at concentrations above 1500 mg kg-1, and that soil organic matter priming primarily affects the carbohydrate fraction of soil organic matter. It can be concluded that the abundance of solid carbohydrates (O-alkyl C) is of paramount importance for the hydrocarbon mineralization under natural conditions, compared to more recalcitrant SOM fractions (mainly aromatic and alkyl C). References Mykhailova, L., Fischer, T., Iurchenko, V. (2013) Distribution and fractional composition of petroleum hydrocarbons in roadside soils. Applied and Environmental Soil Science, vol. 2013, Article ID 938703, 6 pages, DOI 10.1155/2013/938703 Mykhailova, L., Fischer, T., Iurchenko, V. (2014) Deposition of petroleum hydrocarbons with sediment trapped in snow in roadside areas. Journal of Environmental Engineering and Landscape Management 22(3):237-244, DOI 10.3846/16486897.2014.889698 Nelson P.N. and Baldock J.A. (2005) Estimating the molecular composition of a diverse range of natural organic materials from solid-state 13C NMR and elemental analyses, 2005, Biogeochemistry (2005) 72: 1-34, DOI 10.1007/s10533-004-0076-3 Zyakun, A., Nii-Annang, S., Franke, G., Fischer, T., Buegger, F., Dilly, O. (2011) Microbial Actvity and 13C/12C Ratio as Evidence of N-Hexadecane and N-Hexadecanoic Acid Biodegradation in Agricultural and Forest Soils. Geomicrobiology Journal 28:632-647, DOI 10.1080/01490451.2010.489922

  18. Changes of Organic Carbon Quantity and Quality in Temperate Forest Soils

    Science.gov (United States)

    Kühnel, Anna; Satwika Lestari, Annisa; Schubert, Alfred; Wiesmeier, Martin; Spörlein, Peter; Schilling, Bernd; Kögel-Knabner, Ingrid

    2017-04-01

    Climate change will have profound impacts on organic matter stocks and thus on the functionality of soils. Soil organic carbon (SOC) content in soil is mainly regulated by the fluxes of organic matter which are highly associated with the aboveground and root litter production and their decompositions into CO2 by soil microorganism. The predicted rising temperatures in Bavaria might lead to an increased decomposition and release of soil carbon into the atmosphere, which would deteriorate a number of important soil functions. Here, we present an assessment of SOC stocks in three temperate forest sites over the last 30 years. Soil to a depth of 30 cm was analysed with density fractionation to evaluate SOC stocks and distribution in different pools. Additionally, tree-aboveground organic carbon (OC) stocks were measured to assess their influence on SOC. SOC stocks decreased between 1988 and 2004 and increased between 2004 and 2016. OC changes of litter + O layer and mineral soil differed. Highest changes of SOC occurred in the light fractions, followed by the mineral fractions. Tree-aboveground biomass, stand composition, and changing climate had an influence on SOC stocks. Precipitation change was correlated with the litter + O layer OC stocks. Further studies on the changes of each SOC fraction and the influence of other edaphic factors are needed to better understand the changes in SOC stocks and quality.

  19. Long-term effects of plant diversity and composition on soil nematode communities in grassland.

    NARCIS (Netherlands)

    Viketoft, M.; Bengtsson, J.; Sohlenius, B.; Berg, M.P.; Petchey, O.; Palmborg, C.; Huss-Daniel, K.

    2009-01-01

    An important component of plant-soil feedbacks is how plant species identity and diversity influence soil organism communities. We examine the effects of grassland plant species growing alone and together up to a richness of 12 species on nematode diversity and feeding group composition, eight years

  20. Nutritional status, yield and composition of peach fruit subjected to the application of organic compost

    Directory of Open Access Journals (Sweden)

    George Wellington Bastos de Melo

    2016-01-01

    Full Text Available The purpose of this study was to evaluate the nutritional state, yield and composition of peaches on peach trees subjected to the application of organic compost to the soil. This experiment was conducted during the 2008 and 2009 cropping season in an orchard containing Chimarrita cultivars grafted onto Capdeboscq rootstocks and Haplumbrept soils in the municipality of Farroupilha (RS, Brazil. The treatments included 0, 9, 18, 36, 72 and 144 liters of organic compost per plant-1 year-1. The total nutrient contents in the leaves, yield components, yields per plant and hectare and compositions of the fruits were evaluated in 2008 and 2009 soon after harvest and after 30 days of storage. The application of organic compost to the soil increased the yield components and the yields per plant and hectare in the two treatments with the highest compost additions, which indicated that the addition of 72 L of compost per plant-1 is ideal economically. The organic compost had little effect on the composition of the peach fruit after harvest and after 30 days of storage.

  1. Response of soil organic carbon fractions, microbial community composition and carbon mineralization to high-input fertilizer practices under an intensive agricultural system

    Science.gov (United States)

    Wu, Xueping; Gebremikael, Mesfin Tsegaye; Wu, Huijun; Cai, Dianxiong; Wang, Bisheng; Li, Baoguo; Zhang, Jiancheng; Li, Yongshan; Xi, Jilong

    2018-01-01

    Microbial mechanisms associated with soil organic carbon (SOC) decomposition are poorly understood. We aim to determine the effects of inorganic and organic fertilizers on soil labile carbon (C) pools, microbial community structure and C mineralization rate under an intensive wheat-maize double cropping system in Northern China. Soil samples in 0–10 cm layer were collected from a nine-year field trial involved four treatments: no fertilizer, CK; nitrogen (N) and phosphorus (P) fertilizers, NP; maize straw combined with NP fertilizers, NPS; and manure plus straw and NP fertilizers, NPSM. Soil samples were analyzed to determine labile C pools (including dissolved organic C, DOC; light free organic C, LFOC; and microbial biomass C, MBC), microbial community composition (using phospholipid fatty acid (PLFA) profiles) and SOC mineralization rate (from a 124-day incubation experiment). This study demonstrated that the application of chemical fertilizers (NP) alone did not alter labile C fractions, soil microbial communities and SOC mineralization rate from those observed in the CK treatment. Whereas the use of straw in conjunction with chemical fertilizers (NPS) became an additional labile substrate supply that decreased C limitation, stimulated growth of all PLFA-related microbial communities, and resulted in 53% higher cumulative mineralization of C compared to that of CK. The SOC and its labile fractions explained 78.7% of the variance of microbial community structure. Further addition of manure on the top of straw in the NPSM treatment did not significantly increase microbial community abundances, but it did alter microbial community structure by increasing G+/G- ratio compared to that of NPS. The cumulative mineralization of C was 85% higher under NPSM fertilization compared to that of CK. Particularly, the NPSM treatment increased the mineralization rate of the resistant pool. This has to be carefully taken into account when setting realistic and effective goals

  2. Optical Properties of Airborne Soil Organic Particles

    Energy Technology Data Exchange (ETDEWEB)

    Veghte, Daniel P. [William; China, Swarup [William; Weis, Johannes [Chemical; Department; Kovarik, Libor [William; Gilles, Mary K. [Chemical; Laskin, Alexander [Department

    2017-09-27

    Recently, airborne soil organic particles (ASOP) were reported as a type of solid organic particles emitted after water droplets impacted wet soils. Chemical constituents of ASOP are macromolecules such as polysaccharides, tannins, and lignin (derived from degradation of plants and biological organisms). Optical properties of ASOP were inferred from the quantitative analysis of the electron energy-loss spectra acquired over individual particles in the transmission electron microscope. The optical constants of ASOP are further compared with those measured for laboratory generated particles composed of Suwanee River Fulvic Acid (SRFA) reference material, which was used as a laboratory surrogate of ASOP. The particle chemical compositions were analyzed using energy dispersive x-ray spectroscopy, electron energy-loss spectroscopy, and synchrotron-based scanning transmission x-ray microscopy with near edge x-ray absorption fine structure spectroscopy. ASOP and SRFA exhibit similar carbon composition, but SRFA has minor contributions of S and Na. When ASOP are heated to 350 °C their absorption increases as a result of their pyrolysis and partial volatilization of semi-volatile organic constituents. The retrieved refractive index (RI) at 532 nm of SRFA particles, ASOP, and heated ASOP were 1.22-62 0.07i, 1.29-0.07i, and 1.90-0.38i, respectively. Compared to RISRFA, RIASOP has a higher real part but similar imaginary part. These measurements of ASOP optical constants suggest that they have properties characteristic of atmospheric brown carbon and therefore their potential effects on the radiative forcing of climate need to be assessed in atmospheric models.

  3. Effects of organic amendments and mulches on soil microbial communities in quarry restoration under semiarid climate

    Science.gov (United States)

    Luna Ramos, Lourdes; Pastorelli, Roberta; Miralles Mellado, Isabel; Fabiani, Arturo; Bastida López, Felipe; Hernández Fernández, María Teresa; García Izquierdo, Carlos; Solé Benet, Albert

    2015-04-01

    Mining activities generate loss of the quality of the environment and landscape specially in arid and semiarid Mediterranean regions. A precondition for ecosystem reclamation in such highly disturbed mining areas is the development of functional soils with appropriate levels of organic matter. In an experimental soil restoration in limestone quarries from Sierra de Gádor (Almería), SE Spain, 9 plots 15 x 5 m were prepared to test organic amendments (compost from solid urban residues-DOW-, sludge from urban water treatment-SS-, control-NA-) and different mulches (fine gravel-GM-, wood chips-WM-, control-NM-) with the aim to improve soil/substrate properties and to reduce evaporation and erosion. In each experimental plot, 75 native plants (Macrochloa tenacissima, Anthyllis terniflora and Anthyllis cytisoides) were planted. After 5 years from the start of the experiment, we evaluated how microbial community composition responded to the organic amendments and mulches. Microbial community composition of both bacteria and fungi was determined by phospholipid fatty acid (PLFA) and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) fingerprinting. The results of the two-way ANOVA showed that PLFAs were significantly affected by organic amendments but not by the mulches or interaction of both factors. Experimental plots with DOW showed significantly higher level of fungal PLFAs than those with SS and NA, even higher than the reference undisturbed soil. However, any plot with organic amendments did not reach the content of bacterial PLFAs of the reference soils. The bacterial diversity (evaluated by diversity indices calculated from DGGE profiles) was greater in soil samples taken under NA and GM. Comparing these indices in fungal DGGE, we found greater values for soil samples taken under DOW and without mulches. Results from UPGMA analysis showed significant differences in the structure of soil bacterial communities from the different treatments

  4. Chemistry of organic carbon in soil with relationship to the global carbon cycle

    International Nuclear Information System (INIS)

    Post, W.M. III.

    1988-01-01

    Various ecosystem disturbances alter the balances between production of organic matter and its decomposition and therefore change the amount of carbon in soil. The most severe perturbation is conversion of natural vegetation to cultivated crops. Conversion of natural vegetation to cultivated crops results in a lowered input of slowly decomposing material which causes a reduction in overall carbon levels. Disruption of soil matrix structure by cultivation leads to lowered physical protection of organic matter resulting in an increased net mineralization rate of soil carbon. Climate change is another perturbation that affects the amount and composition of plant production, litter inputs, and decomposition regimes but does not affect soil structure directly. Nevertheless, large changes in soil carbon storage are probable with anticipated CO 2 induced climate change, particularly in northern latitudes where anticipated climate change will be greatest (MacCracken and Luther 1985) and large amounts of soil organic matter are found. It is impossible, given the current state of knowledge of soil organic matter processes and transformations to develop detailed process models of soil carbon dynamics. Largely phenomenological models appear to be developing into predictive tools for understanding the role of soil organic matter in the global carbon cycle. In particular, these models will be useful in quantifying soil carbon changes due to human land-use and to anticipated global climate and vegetation changes. 47 refs., 7 figs., 2 tabs

  5. Two-dimensional NMR spectroscopy as a tool to link soil organic matter composition to ecosystem processes

    Science.gov (United States)

    Soucemarianadin, Laure; Erhagen, Björn; Öquist, Mats; Nilsson, Mats; Schleucher, Jürgen

    2014-05-01

    Environmental factors (e.g. temperature and moisture) and the size and composition of soil microbial populations are often considered the main drivers of soil organic matter (SOM) mineralization. Less consideration is given to the role of SOM as a substrate for microbial metabolism and the importance of the organo-chemical composition of SOM on decomposition. In addition, a fraction of the SOM is often considered as recalcitrant to mineralization leading to accumulation of SOM. However, recently the concept of intrinsic recalcitrance of SOM to mineralization has been questioned. The challenge in investigating the role of SOM composition on its mineralization to a large extent stems from the difficulties in obtaining high resolution characterization of a very complex matrix. 13C nuclear magnetic resonance (NMR) spectroscopy is a widely used tool to characterize SOM. However, SOM is a very complex mixture and in the resulting 13C NMR spectra, the identified functional groups may represent different molecular fragments that appear in the same spectral region leading to broad peaks. These overlaps defy attempts to identify molecular moieties, and this makes it impossible to derive information at a resolution needed for evaluating e.g. recalcitrance of SOM. Here we applied a method, developed in wood science for the pulp paper industry, to achieve a better characterization of SOM. We directly dissolved finely ground organic layers of boreal forest floors-litters, fibric and humic horizons of both coniferous and broadleaved stands-in dimethyl sulfoxide and analyzed the resulting solution with a two-dimensional (2D) 1H-13C NMR experiment. We will discuss methodological aspects related to the ability to identify and quantify individual molecular moieties in SOM. We will demonstrate how the spectra resolve signals of CH groups in a 2D plane determined by the 13C and 1H chemical shifts, thereby vastly increasing the resolving power and information content of NMR spectra. The

  6. Soil Organic Matter Stability and Soil Carbon Storage with Changes in Land Use Intensity in Uganda

    Science.gov (United States)

    Tiemann, L. K.; Grandy, S.; Hartter, J.

    2014-12-01

    As the foundation of soil fertility, soil organic matter (SOM) formation and break-down is a critical factor of agroecosystem sustainability. In tropical systems where soils are quickly weathered, the link between SOM and soil fertility is particularly strong; however, the mechanisms controlling the stabilization and destabilization of SOM are not well characterized in tropical soils. In western Uganda, we collected soil samples under different levels of land use intensity including maize fields, banana plantations and inside an un-cultivated native tropical forest, Kibale National Park (KNP). To better understand the link between land use intensity and SOM stability we measured total soil C and N, and respiration rates during a 369 d soil incubation. In addition, we separated soils into particle size fractions, and mineral adsorbed SOM in the silt (2-50 μm ) and clay (fractions was dissociated, purified and chemically characterized via pyrolysis-GC/MS. Cultivated soil C and N have declined by 22 and 48%, respectively, in comparison to uncultivated KNP soils. Incubation data indicate that over the last decade, relatively accessible and labile soil organic carbon (SOC) pools have been depleted by 55-59% in cultivated soils. As a result of this depletion, the chemical composition of SOM has been altered such that clay and silt associated SOM differed significantly between agricultural fields and KNP. In particular, nitrogen containing compounds were in lower abundance in agricultural compared to KNP soils. This suggests that N depletion due to agriculture has advanced to pools of mineral associated organic N that are typically protected from break-down. In areas where land use intensity is relatively greater, increases in polysaccharides and lipids in maize fields compared to KNP indicate increases in microbial residues and decomposition by-products as microbes mine SOM for organic N. Chemical characterization of post-incubation SOM will help us better understand

  7. The influence of wildfire severity on soil char composition and nitrogen dynamics

    Science.gov (United States)

    Rhoades, Charles; Fegel, Timothy; Chow, Alex; Tsai, Kuo-Pei; Norman, John, III; Kelly, Eugene

    2017-04-01

    Forest fires cause lasting ecological changes and alter the biogeochemical processes that control stream water quality. Decreased plant nutrient uptake is the mechanism often held responsible for lasting post-fire shifts in nutrient supply and demand, though other upland and in-stream factors also likely contribute to elevated stream nutrient losses. Soil heating, for example, creates pyrogenic carbon (C) and char layers that influence C and nitrogen (N) cycling. Char layer composition and persistence vary across burned landscapes and are influenced first by fire behavior through the temperature and duration of combustion and then by post-fire erosion. To evaluate the link between soil char and stream C and N export we studied areas burned by the 2002 Hayman Fire, the largest wildfire in Colorado, USA history. We compared soil C and N pools and processes across ecotones that included 1) unburned forests, 2) areas with moderate and 3) high wildfire severity. We analyzed 1-2 cm thick charred organic layers that remain visible 15 years after the fire, underlying mineral soils, and soluble leachate from both layers. Unburned soils released more dissolved organic C and N (DOC and DON) from organic and mineral soil layers than burned soils. The composition of DOC leachate characterized by UV-fluorescence, emission-excitation matrices (EEMs) and Fluorescence Regional Integration (FRI) found similarity between burned and unburned soils, underscoring a common organic matter source. Humic and fulvic acid-like fractions, contained in regions V and III of the FRI model, comprised the majority of the fluorescing DOM in both unburned and char layers. Similarity between two EEMs indices (Fluorescence and Freshness), further denote that unburned soils and char layers originate from the same source and are consistent with visual evidence char layers contain significant amounts of unaltered OM. However, the EEMs humification index (HIX) and compositional analysis with pyrolysis GCMS

  8. Microbial community composition affects soil fungistasis.

    Science.gov (United States)

    de Boer, Wietse; Verheggen, Patrick; Klein Gunnewiek, Paulien J A; Kowalchuk, George A; van Veen, Johannes A

    2003-02-01

    Most soils inhibit fungal germination and growth to a certain extent, a phenomenon known as soil fungistasis. Previous observations have implicated microorganisms as the causal agents of fungistasis, with their action mediated either by available carbon limitation (nutrient deprivation hypothesis) or production of antifungal compounds (antibiosis hypothesis). To obtain evidence for either of these hypotheses, we measured soil respiration and microbial numbers (as indicators of nutrient stress) and bacterial community composition (as an indicator of potential differences in the composition of antifungal components) during the development of fungistasis. This was done for two fungistatic dune soils in which fungistasis was initially fully or partly relieved by partial sterilization treatment or nutrient addition. Fungistasis development was measured as restriction of the ability of the fungi Chaetomium globosum, Fusarium culmorum, Fusarium oxysporum, and Trichoderma harzianum to colonize soils. Fungistasis did not always reappear after soil treatments despite intense competition for carbon, suggesting that microbial community composition is important in the development of fungistasis. Both microbial community analysis and in vitro antagonism tests indicated that the presence of pseudomonads might be essential for the development of fungistasis. Overall, the results lend support to the antibiosis hypothesis.

  9. Spatial distribution of soil organic carbon stocks in France

    Directory of Open Access Journals (Sweden)

    M. P. Martin

    2011-05-01

    Full Text Available Soil organic carbon plays a major role in the global carbon budget, and can act as a source or a sink of atmospheric carbon, thereby possibly influencing the course of climate change. Changes in soil organic carbon (SOC stocks are now taken into account in international negotiations regarding climate change. Consequently, developing sampling schemes and models for estimating the spatial distribution of SOC stocks is a priority. The French soil monitoring network has been established on a 16 km × 16 km grid and the first sampling campaign has recently been completed, providing around 2200 measurements of stocks of soil organic carbon, obtained through an in situ composite sampling, uniformly distributed over the French territory.

    We calibrated a boosted regression tree model on the observed stocks, modelling SOC stocks as a function of other variables such as climatic parameters, vegetation net primary productivity, soil properties and land use. The calibrated model was evaluated through cross-validation and eventually used for estimating SOC stocks for mainland France. Two other models were calibrated on forest and agricultural soils separately, in order to assess more precisely the influence of pedo-climatic variables on SOC for such soils.

    The boosted regression tree model showed good predictive ability, and enabled quantification of relationships between SOC stocks and pedo-climatic variables (plus their interactions over the French territory. These relationships strongly depended on the land use, and more specifically, differed between forest soils and cultivated soil. The total estimate of SOC stocks in France was 3.260 ± 0.872 PgC for the first 30 cm. It was compared to another estimate, based on the previously published European soil organic carbon and bulk density maps, of 5.303 PgC. We demonstrate that the present estimate might better represent the actual SOC stock distributions of France, and consequently that the

  10. Wind sorting affects differently the organo-mineral composition of saltating and particulate materials in contrasting texture agricultural soils

    Science.gov (United States)

    Iturri, Laura Antonela; Funk, Roger; Leue, Martin; Sommer, Michael; Buschiazzo, Daniel Eduardo

    2017-10-01

    There is little information about the mineral and organic composition of sediments eroded by wind at different heights. Because of that, wind tunnel simulations were performed on four agricultural loess soils of different granulometry and their saltating materials collected at different heights. The particulate matter with an aerodynamic diameter mainly smaller than 10 μm (PM10) of these soils was obtained separately by a laboratory method. Results indicated that the granulometric composition of sediments collected at different heights was more homogeneous in fine- than in sandy-textured soils, which were more affected by sorting effects during wind erosion. This agrees with the preferential transport of quartz at low heights and of clay minerals at greater heights. SOC contents increased with height, but the composition of the organic materials was different: stable carboxylic acids, aldehydes, amides and aromatics were preferentially transported close to the ground because their were found in larger aggregates, while plant debris and polysaccharides, carbohydrates and derivatives of microbial origin from organic matter dominated at greater heights for all soil types. The amount of SOC in the PM10 fraction was higher when it was emitted from sandy than from fine textured soils. Because of the sorting process produced by wind erosion, the stable organic matter compounds will be transported at low heights and local scales, modifying soil fertility due to nutrient exportation, while less stable organic compounds will be part of the suspension losses, which are known to affect some processes at regional- or global scale.

  11. Organic compounds in hot-water-soluble fractions from water repellent soils

    Science.gov (United States)

    Atanassova, Irena; Doerr, Stefan

    2014-05-01

    Water repellency (WR) is a soil property providing hydrophobic protection and preventing rapid microbial decomposition of organic matter entering the soil with litter or plant residues. Global warming can cause changes in WR, thus influencing water storage and plant productivity. Here we assess two different approaches for analysis of organic compounds composition in hot water extracts from accelerated solvent extraction (ASE) of water repellent soils. Extracts were lyophilized, fractionated on SiO2 (sand) and SPE cartridge, and measured by GC/MS. Dominant compounds were aromatic acids, short chain dicarboxylic acids (C4-C9), sugars, short chain fatty acids (C8-C18), and esters of stearic and palmitic acids. Polar compounds (mainly sugars) were adsorbed on applying SPE clean-up procedure, while esters were highly abundant. In addition to the removal of polar compounds, hydrophobic esters and hydrocarbons (alkanes and alkenes particle wettability and C dynamics in soils. Key words: soil water repellency, hot water soluble carbon (HWSC), GC/MS, hydrophobic compounds

  12. Experimental soil warming shifts the fungal community composition at the alpine treeline.

    Science.gov (United States)

    Solly, Emily F; Lindahl, Björn D; Dawes, Melissa A; Peter, Martina; Souza, Rômulo C; Rixen, Christian; Hagedorn, Frank

    2017-07-01

    Increased CO 2 emissions and global warming may alter the composition of fungal communities through the removal of temperature limitation in the plant-soil system, faster nitrogen (N) cycling and changes in the carbon (C) allocation of host plants to the rhizosphere. At a Swiss treeline featuring Larix decidua and Pinus uncinata, the effects of multiple years of CO 2 enrichment and experimental soil warming on the fungal community composition in the organic horizons were analysed using 454-pyrosequencing of ITS2 amplicons. Sporocarp production and colonization of ectomycorrhizal root tips were investigated in parallel. Fungal community composition was significantly altered by soil warming, whereas CO 2 enrichment had little effect. Tree species influenced fungal community composition and the magnitude of the warming responses. The abundance of ectomycorrhizal fungal taxa was positively correlated with N availability, and ectomycorrhizal taxa specialized for conditions of high N availability proliferated with warming, corresponding to considerable increases in inorganic N in warmed soils. Traits related to N utilization are important in determining the responses of ectomycorrhizal fungi to warming in N-poor cold ecosystems. Shifts in the overall fungal community composition in response to higher temperatures may alter fungal-driven processes with potential feedbacks on ecosystem N cycling and C storage at the alpine treeline. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  13. Bacterial diversity in Greenlandic soils as affected by potato cropping and inorganic versus organic fertilization

    DEFF Research Database (Denmark)

    Michelsen, Charlotte Frydenlund; Pedas, Pai Rosager; Glaring, Mikkel Andreas

    2014-01-01

    research has been performed on the effects of these treatments on bacterial communities in Arctic and Subarctic agricultural soils. The major objective of this study was to investigate the short-term impact of conventional (NPK) and organic (sheep manure supplemented with nitrogen) fertilizer treatments...... with only limited pest management, despite the presence of plant pathogenic fungi. The microbial community composition in agricultural soils, which plays an important role for soil and plant health and for crop yield, may be affected by the use of different fertilizer treatments. Currently, only limited...... on bacterial diversity, nutrient composition and crop yield in two Greenlandic agricultural soils. An effect of fertilizer was found on soil and plant nutrient levels and on crop yields. Pyrosequencing of 16S rRNA gene sequences did not reveal any major changes in the overall bacterial community composition...

  14. Correlation between Soil Organic Matter, Total Organic Matter and ...

    African Journals Online (AJOL)

    A total of four sites distributed in different soils of Kelantan State, Malaysia was identified for the study. Soils were collected by depth interval of 0-10cm, 10-20cm and 20-30cm. The correlation of soil organic matter (SOM) content, total organic carbon (TOC) content, water content and soils texture for industrial area at ...

  15. Soil Organic Carbon in the Soil Scapes of Southeastern Tanzania

    OpenAIRE

    Rossi, Joni

    2009-01-01

    Soil organic carbon (SOC) is well known to maintain several functions. On the one hand, being the major component of soil organic matter (SOM),it is a determinant of soil physical and chemical properties, an important proxy for soil biological activity and a measure of soil productivity. Land use management that will enhance soil carbon (C) levels is therefore important for farmers and land use planners, particularly in semiarid and sub-humid Africa where severe soil degradation and desertifi...

  16. Rhizosphere Environment and Labile Phosphorus Release from Organic Waste-Amended Soils.

    Science.gov (United States)

    Dao, Thanh H.

    2015-04-01

    Crop residues and biofertilizers are primary sources of nutrients for organic crop production. However, soils treated with large amounts of nutrient-enriched manure have elevated phosphorus (P) levels in regions of intensive animal agriculture. Surpluses occurred in these amended soils, resulting in large pools of exchangeable inorganic P (Pi) and enzyme-labile organic P (Po) that averaging 30.9 and 68.2 mg kg-1, respectively. Organic acids produced during crop residue decomposition can promote the complexation of counter-ions and decouple and release unbound Pi from metal and alkali metal phosphates. Animal manure and cover crop residues also contain large amounts of soluble organic matter, and likely generate similar ligands. However, a high degree of heterogeneity in P spatial distribution in such amended fields, arising from variances in substrate physical forms ranging from slurries to dried solids, composition, and diverse application methods and equipment. Distinct clusters of Pi and Po were observed, where accumulation of the latter forms was associated with high soil microbial biomass C and reduced phosphomonoesterases' activity. Accurate estimates of plant requirements and lability of soil P pools, and real-time plant and soil P sensing systems are critical considerations to optimally manage manure-derived nutrients in crop production systems. An in situ X-ray fluorescence-based approach to sensing canopy and soil XRFS-P was developed to improve the yield-soil P relationship for optimal nutrient recommendations in addition to allowing in-the-field verification of foliar P status.

  17. Soil management practices under organic farming

    Science.gov (United States)

    Aly, Adel; Chami Ziad, Al; Hamdy, Atef

    2015-04-01

    Organic farming methods combine scientific knowledge of ecology and modern technology with traditional farming practices based on naturally occurring biological processes. Soil building practices such as crop rotations, intercropping, symbiotic associations, cover crops, organic fertilizers and minimum tillage are central to organic practices. Those practices encourage soil formation and structure and creating more stable systems. In farm nutrient and energy cycling is increased and the retentive abilities of the soil for nutrients and water are enhanced. Such management techniques also play an important role in soil erosion control. The length of time that the soil is exposed to erosive forces is decreased, soil biodiversity is increased, and nutrient losses are reduced, helping to maintain and enhance soil productivity. Organic farming as systematized and certifiable approach for agriculture, there is no surprise that it faces some challenges among both farmers and public sector. This can be clearly demonstrated particularly in the absence of the essential conditions needed to implement successfully the soil management practices like green manure and composting to improve soil fertility including crop rotation, cover cropping and reduced tillage. Those issues beside others will be fully discussed highlighting their beneficial impact on the environmental soil characteristics. Keywords: soil fertility, organic matter, plant nutrition

  18. Soil pH is a Key Determinant of Soil Fungal Community Composition in the Ny-Ålesund Region, Svalbard (High Arctic)

    Science.gov (United States)

    Zhang, Tao; Wang, Neng-Fei; Liu, Hong-Yu; Zhang, Yu-Qin; Yu, Li-Yan

    2016-01-01

    This study assessed the fungal community composition and its relationships with properties of surface soils in the Ny-Ålesund Region (Svalbard, High Arctic). A total of thirteen soil samples were collected and soil fungal community was analyzed by 454 pyrosequencing with fungi-specific primers targeting the rDNA internal transcribed spacer (ITS) region. The following eight soil properties were analyzed: pH, organic carbon (C), organic nitrogen (N), ammonium nitrogen (NH4+-N), silicate silicon (SiO42--Si), nitrite nitrogen (NO2--N), phosphate phosphorus (PO43--P), and nitrate nitrogen (NO3--N). A total of 57,952 reads belonging to 541 operational taxonomic units (OTUs) were found. of these OTUs, 343 belonged to Ascomycota, 100 to Basidiomycota, 31 to Chytridiomycota, 22 to Glomeromycota, 11 to Zygomycota, 10 to Rozellomycota, whereas 24 belonged to unknown fungi. The dominant orders were Helotiales, Verrucariales, Agaricales, Lecanorales, Chaetothyriales, Lecideales, and Capnodiales. The common genera (>eight soil samples) were Tetracladium, Mortierella, Fusarium, Cortinarius, and Atla. Distance-based redundancy analysis (db-rda) and analysis of similarities (ANOSIM) revealed that soil pH (p = 0.001) was the most significant factor in determining the soil fungal community composition. Members of Verrucariales were found to predominate in soils of pH 8–9, whereas Sordariales predominated in soils of pH 7–8 and Coniochaetales predominated in soils of pH 6–7. The results suggest the presence and distribution of diverse soil fungal communities in the High Arctic, which can provide reliable data for studying the ecological responses of soil fungal communities to climate changes in the Arctic. PMID:26955371

  19. Soil pH is a key determinant of soil fungal community composition in the Ny-Ålesund Region, Svalbard (High Arctic

    Directory of Open Access Journals (Sweden)

    Tao eZhang

    2016-02-01

    Full Text Available This study assessed the fungal community composition and its relationships with properties of surface soils in the Ny-Ålesund Region (Svalbard, High Arctic. A total of thirteen soil samples were collected and soil fungal community was analyzed by 454 pyrosequencing with fungi-specific primers targeting the rDNA internal transcribed spacer (ITS region. The following eight soil properties were analyzed: pH, organic carbon (C, organic nitrogen (N, ammonium nitrogen (NH4+-N, silicate silicon (SiO42--Si, nitrite nitrogen (NO2--N, phosphate phosphorus (PO43--P and nitrate nitrogen (NO3--N. A total of 57,952 reads belonging to 541 operational taxonomic units (OTUs were found. Of these OTUs, 343 belonged to Ascomycota, 100 to Basidiomycota, 31 to Chytridiomycota, 22 to Glomeromycota, 11 to Zygomycota, 10 to Rozellomycota, whereas 24 belonged to unknown fungi. The dominant orders were Helotiales, Verrucariales, Agaricales, Lecanorales, Chaetothyriales, Lecideales, and Capnodiales. The common genera (>8 soil samples were Tetracladium, Mortierella, Fusarium, Cortinarius, and Atla. Distance-based redundancy analysis (db-rda and analysis of similarities (ANOSIM revealed that soil pH (p=0.001 was the most significant factor in determining the soil fungal community composition. Members of Verrucariales were found to predominate in soils of pH 8-9, whereas Sordariales predominated in soils of pH 7-8 and Coniochaetales predominated in soil samples of pH 6-7. The results suggest the presence and distribution of diverse soil fungal communities in the High Arctic, which can provide reliable data for studying the ecological responses of soil fungal communities to climate changes in the Arctic.

  20. Soil fertility management: Impacts on soil macrofauna, soil aggregation and soil organic matter allocation.

    NARCIS (Netherlands)

    Ayuke, F.O.; Brussaard, L.; Vanlauwe, B.; Six, J.; Lelei, D.K.; Kibunja, C.N.; Pulleman, M.M.

    2011-01-01

    Maintenance of soil organic matter through integrated soil fertility management is important for soil quality and agricultural productivity, and for the persistence of soil faunal diversity and biomass. Little is known about the interactive effects of soil fertility management and soil macrofauna

  1. Soil Organic Matter to Soil Organic Carbon ratios in recovered mountain peatlands using Vis-Nir spectroscopy approach.

    Science.gov (United States)

    Fernandez, Susana del Carmen; Valderrabano, Jesus; Peon, Juan Jose; Bueno, Alvaro

    2015-04-01

    samples was taken. The PCA (Principal Component Analysis) to spectra by soil population was performed in order to recognise the molecular composition of the soil carbon of the peatlands inside and outside the fences and the changes suffered with the transformation of the soil environment by the lack of herbivores pressure. At the time 0 there are not carbonates in the soil samples analysed, also not differences in pH; TOC and OC inside or outside the fences area found. Nevertheless in Liordes pH values reaches 7. 48 and in Comella not surpasses 5.0. Respect Soil Organic Carbon Liordes has a maximum of 48.4 g of TOC and 42.8 g of OC/Kg and Comella 59.2g of TOC and 47.1g/ Kg. There is not too much difference between TOC and SOC amounts highlighting the fact that most of the organic matter in soils correspond to poorly evolve organic matter. The Nir spectra (350-2500nm) reveal the presence of cellulose amorphous and carbohydrates (peaks at ~1500 and ~2000 nm) as the main components of these soils.

  2. Organic management and cover crop species steer soil microbial community structure and functionality along with soil organic matter properties

    NARCIS (Netherlands)

    Martínez-García, Laura B.; Korthals, Gerard; Brussaard, Lijbert; Jørgensen, Helene Bracht; Deyn, de Gerlinde B.

    2018-01-01

    It is well recognized that organic soil management stimulates bacterial biomass and activity and that including cover crops in the rotation increases soil organic matter (SOM). Yet, to date the relative impact of different cover crop species and organic vs. non-organic soil management on soil

  3. The Effect of Climate change on Soil Organic Matter Decomposition

    Directory of Open Access Journals (Sweden)

    TÓTH, János Attila

    2007-01-01

    Full Text Available In the last few decades the climate of Síkfkút ILTER Forest (Hungary became warmerand dryer. Due to the climate change the species composition of forest has been changing, and thetotal leaf litter production has been slightly decreasing. According to our long-term litter manipulationfield experiment, which is part of ILTER Detritus Input and Removal Treatments (DIRT Project, aftera 4-5 year treating period, at the No Litter, No Root and No Input treatments the soil organic C and Ncontent, the soil bacterial and fungal count, the soil pH, the soil enzyme activity, and soil respirationdecreased. Increased soil temperature raises soil respiration exponentially, and thus if the average soiltemperature increased by 2 oC at the dry Síkfkút site, soil respiration would increase by 22.1%. Thisincrease would be higher (29.9% at a wet site, such as Harvard Forest in the USA. Increasing soilrespiration can speed up global warming through a positive feedback mechanism.

  4. Molecular characterization of soil organic matter from native vegetation–pasture–sugarcane transitions in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Dener Márcio da Silva, E-mail: denermsoliveira@gmail.com [University of São Paulo, Luiz de Queiroz College of Agriculture, Department of Soil Science, 11 Páduas Dias Avenue, 13418-900 Piracicaba, SP (Brazil); Colorado State University, Natural Resource Ecology Laboratory, 1231 East Drive, 80523-1499 Fort Collins, CO (United States); Schellekens, Judith; Cerri, Carlos Eduardo Pellegrino [University of São Paulo, Luiz de Queiroz College of Agriculture, Department of Soil Science, 11 Páduas Dias Avenue, 13418-900 Piracicaba, SP (Brazil)

    2016-04-01

    Replacing pastures (PA) with sugarcane (SG) has been deemed an agronomically feasible strategy for sugarcane expansion in Brazil. However, there are some uncertainties about the environmental impacts regarding this land use change (LUC), mainly related to soil organic matter (SOM), a key factor of environmental sustainability of Brazilian ethanol. LUC-related losses of SOM can overcome the C savings from biofuels. The molecular composition of SOM was evaluated to understand the C dynamics regarding LUC from PA to SG, using native vegetation (NV) as reference. Our study area was located in the south-central region of Brazil. Soil sampling was performed at three depths (0–0.1 m, 0.2–0.3 m and 0.9–1 m) in three representative sites with known LUC history and management practice since 1970. Pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) was chosen to study SOM chemistry. Content and isotopic composition of soil organic C and N were also determined. The LUC caused decreases on C and N contents and on δ{sup 13}C isotopic values. Depth was the major factor that influenced SOM composition, while the influence of LUC was mainly evident in surface soils and diminished rapidly with depth. The main difference in SOM composition undergoing the conversion PA-SG was a higher contribution from compounds associated to fresh litter inputs. The high contribution from fresh litter, having a relatively low mean residence time and increasing decomposition rates, is probably a major factor that drives C losses in areas undergoing sugarcane expansion. - Graphical abstract: We chose 3 sites in Brazil (1) and collected soil samples in areas undergoing LUC pasture–sugarcane (2) to evaluate SOM composition using Py–GC/MS (3). The LUC causes shifts on SOM signature (4), highlighting the increase of fresh litter compounds in sugarcane areas (5). - Highlights: • Effect of land use change (LUC) on SOM composition in Brazilian soils • Py-GC/MS of NaOH extractable SOM

  5. Impact of rice cultivar and organ on elemental composition of phytoliths and the release of bio-available silicon

    Directory of Open Access Journals (Sweden)

    Zimin eLi

    2014-10-01

    Full Text Available The continental bio-cycling of silicon (Si plays a key role in global Si cycle and as such partly controls global carbon (C budget through nutrition of marine and terrestrial biota, accumulation of phytolith-occluded organic carbon (PhytOC and weathering of silicate minerals. Despite the key role of elemental composition of phytoliths on their solubility in soils, the impact of plant cultivar and organ on the elemental composition of phytoliths in Si high-accumulator plants, such as rice (Oryza sativa is not yet fully understood. Here we show that rice cultivar significantly impacts the elemental composition of phytoliths (Si, Al, Fe and C in different organs of the shoot system (grains, sheath, leaf and stem. The amount of occluded OC within phytoliths is affected by contents of Si, Al and Fe in plants, while independent of the element composition of phytoliths. Our data document, for different cultivars, higher bio-available Si release from phytoliths of leaves and sheaths, which are characterized by higher enrichment with Al and Fe (i.e., lower Si/Al and Si/Fe ratios, compared to grains and stems. We indicate that phytolith solubility in soils may be controlled by rice cultivar and type of organs. Our results highlight that the role of the morphology, the hydration rate and the chemical composition in the solubility of phytoliths and the kinetic release of Si in soil solution needs to be studied further. This is central to a better understanding of the impact of soil amendment with different plant organs and cultivars on soil OC stock and on the delivery of dissolved Si as we show that sheath and leaf rice organs are both characterized by higher content of OC occluded in phytolith and higher phytolith solubility compared to grains and stems. Our study shows the importance of studying the impact of the agro-management on the evolution of sinks and sources of Si and C in soils used for Si-high accumulator plants.

  6. Effect of land use and soil organic matter quality on the structure and function of microbial communities in pastoral soils: Implications for disease suppression.

    Science.gov (United States)

    Dignam, Bryony E A; O'Callaghan, Maureen; Condron, Leo M; Kowalchuk, George A; Van Nostrand, Joy D; Zhou, Jizhong; Wakelin, Steven A

    2018-01-01

    Cropping soils vary in extent of natural suppression of soil-borne plant diseases. However, it is unknown whether similar variation occurs across pastoral agricultural systems. We examined soil microbial community properties known to be associated with disease suppression across 50 pastoral fields varying in management intensity. The composition and abundance of the disease-suppressive community were assessed from both taxonomic and functional perspectives. Pseudomonas bacteria were selected as a general taxonomic indicator of disease suppressive potential, while genes associated with the biosynthesis of a suite of secondary metabolites provided functional markers (GeoChip 5.0 microarray analysis). The composition of both the Pseudomonas communities and disease suppressive functional genes were responsive to land use. Underlying soil properties explained 37% of the variation in Pseudomonas community structure and up to 61% of the variation in the abundance of disease suppressive functional genes. Notably, measures of soil organic matter quality, C:P ratio, and aromaticity of the dissolved organic matter content (carbon recalcitrance), influenced both the taxonomic and functional disease suppressive potential of the pasture soils. Our results suggest that key components of the soil microbial community may be managed on-farm to enhance disease suppression and plant productivity.

  7. Biological soil crusts: a fundamental organizing agent in global drylands

    Science.gov (United States)

    Belnap, J.; Zhang, Y.

    2013-12-01

    Ecosystem function is profoundly affected by plant community composition, which is ultimately determined by factors that govern seed retention. Dryland ecosystems constitute ~35% of terrestrial surfaces, with most soils in these regions covered by biological soil crusts (biocrusts), a community whose autotrophs are dominated by cyanobacteria, lichens, and mosses. Studies at 550 sites revealed that plant community composition was controlled by the interaction among biocrust type, disturbance regime, and external morphology of seeds. In bare soils (due to disturbance), all seed types were present in the seedbank and plant community. As biocrusts became better developed (i.e., the cover of lichens and mosses increased), they more strongly filtered out seeds with appendages. Thus, soils under late successional biocrusts contained seedbanks dominated by smooth seeds and vascular plants growing in late successional biocrusts were dominated by those with smooth seeds. Therefore, the tension between the removal of biocrusts by soil surface disturbance and their recovery creates a shifting mosaic of plant patch types in both space and time. Because changes in vascular plant communities reverberate throughout both below ground and above ground food webs and thus affect multiple trophic levels, we propose that biocrusts are a fundamental organizing agent in drylands worldwide. Future increased demand for resources will intensify land use both temporally and spatially, resulting in an increased rate of biocrust loss across larger areas. As a result, we can expect shifts in the composition and distribution of plant communities, accompanied by concomitant changes in many aspects of dryland ecosystems. Conceptual model of shifting dryland plant mosaics through space and time. Within the large circles, soil surface type changes with time in the same space, going from bare uncrusted soil (B) to cyanobacterial biocrust (C) to lichen/moss (L/M) biocrust. Disturbance (D) drives the

  8. State-Space Estimation of Soil Organic Carbon Stock

    Science.gov (United States)

    Ogunwole, Joshua O.; Timm, Luis C.; Obidike-Ugwu, Evelyn O.; Gabriels, Donald M.

    2014-04-01

    Understanding soil spatial variability and identifying soil parameters most determinant to soil organic carbon stock is pivotal to precision in ecological modelling, prediction, estimation and management of soil within a landscape. This study investigates and describes field soil variability and its structural pattern for agricultural management decisions. The main aim was to relate variation in soil organic carbon stock to soil properties and to estimate soil organic carbon stock from the soil properties. A transect sampling of 100 points at 3 m intervals was carried out. Soils were sampled and analyzed for soil organic carbon and other selected soil properties along with determination of dry aggregate and water-stable aggregate fractions. Principal component analysis, geostatistics, and state-space analysis were conducted on the analyzed soil properties. The first three principal components explained 53.2% of the total variation; Principal Component 1 was dominated by soil exchange complex and dry sieved macroaggregates clusters. Exponential semivariogram model described the structure of soil organic carbon stock with a strong dependence indicating that soil organic carbon values were correlated up to 10.8m.Neighbouring values of soil organic carbon stock, all waterstable aggregate fractions, and dithionite and pyrophosphate iron gave reliable estimate of soil organic carbon stock by state-space.

  9. [Soil organic carbon fractionation methods and their applications in farmland ecosystem research: a review].

    Science.gov (United States)

    Zhang, Guo; Cao, Zhi-ping; Hu, Chan-juan

    2011-07-01

    Soil organic carbon is of heterogeneity in components. The active components are sensitive to agricultural management, while the inert components play an important role in carbon fixation. Soil organic carbon fractionation mainly includes physical, chemical, and biological fractionations. Physical fractionation is to separate the organic carbon into active and inert components based on the density, particle size, and its spatial distribution; chemical fractionation is to separate the organic carbon into various components based on the solubility, hydrolizability, and chemical reactivity of organic carbon in a variety of extracting agents. In chemical fractionation, the dissolved organic carbon is bio-available, including organic acids, phenols, and carbohydrates, and the acid-hydrolyzed organic carbon can be divided into active and inert organic carbons. Simulated enzymatic oxidation by using KMnO4 can separate organic carbon into active and non-active carbon. Biological fractionation can differentiate microbial biomass carbon and potential mineralizable carbon. Under different farmland management practices, the chemical composition and pool capacity of soil organic carbon fractions will have different variations, giving different effects on soil quality. To identify the qualitative or quantitative relationships between soil organic carbon components and carbon deposition, we should strengthen the standardization study of various fractionation methods, explore the integrated application of different fractionation methods, and sum up the most appropriate organic carbon fractionation method or the appropriate combined fractionation methods for different farmland management practices.

  10. Nonlinear binding of phenanthrene to the extracted fulvic acid fraction in soil in comparison with other organic matter fractions and to the whole soil sample

    International Nuclear Information System (INIS)

    Liu Wenxin; Xu, Shanshan; Xing, Baoshan; Pan, Bo; Tao, Shu

    2010-01-01

    Fractions of soil organic matter in a natural soil were extracted and sorption (or binding) characteristics of phenanthrene on each fraction and to the whole sample were investigated. The organic carbon normalized single point sorption (or binding) coefficient followed lipid > humin (HM) > humic acid (HA) > fulvic acid (FA) > whole soil sample, while the nonlinear exponent exhibited lipid > FA > HA > whole soil sample > HM. FA showed nonlinear binding of phenanthrene as it often does with other fractions. HM and HA contributed the majority of organic carbon in the soil. The calculated sorption coefficients of the whole soil were about two times greater than the measured values at different equilibrium phenanthrene concentrations. As for phenanthrene, the sorption capacity and nonlinearity of the physically mixed HA-HM mixtures were stronger as compared to the chemically reconstituted HA-HM composite. This was attributed to (besides the conditioning effect of the organic solvents) interactions between HA and HM and acid-base additions during fractionation. - Nonlinear binding of phenanthrene to fulvic acid extracted from soil organic matter was found.

  11. Reduced soil cultivation and organic fertilization on organic farms: effects on crop yield and soil physical traits

    Science.gov (United States)

    Surböck, Andreas; Gollner, Gabriele; Klik, Andreas; Freyer, Bernhard; Friedel, Jürgen K.

    2017-04-01

    A continuous investment in soil fertility is necessary to achieve sustainable yields in organic arable farming. Crucial factors here besides the crop rotation are organic fertilization and the soil tillage system. On this topic, an operational group (Project BIOBO*) was established in the frame of an European Innovation Partnership in 2016 consisting of organic farmers, consultants and scientists in the farming region of eastern Austria. The aim of this group is the development and testing of innovative, reduced soil cultivation, green manure and organic fertilization systems under on-farm and on-station conditions to facilitate the sharing and transfer of experience and knowledge within and outside the group. Possibilities for optimization of the farm-specific reduced soil tillage system in combination with green manuring are being studied in field trials on six organic farms. The aim is to determine, how these measures contribute to an increase in soil organic matter contents, yields and income, to an improved nitrogen and nutrient supply to the crops, as well as support soil fertility in general. Within a long-term monitoring project (MUBIL), the effects of different organic fertilization systems on plant and soil traits have been investigated since 2003, when the farm was converted to organic management. The examined organic fertilization systems, i.e. four treatments representing stockless and livestock keeping systems, differ in lucerne management and the supply of organic manure (communal compost, farmyard manure, digestate from a biogas plant). Previous results of this on-station experiment have shown an improvement of some soil properties, especially soil physical properties, since 2003 in all fertilization systems and without differences between them. The infiltration rate of rainwater has increased because of higher hydraulic conductivity. The aggregate stability has shown also positive trends, which reduces the susceptibility to soil erosion by wind and

  12. Distinctive soil organic matter composition in a precipitation contrast of a Hawaiian Andosol

    Science.gov (United States)

    Inagaki, Thiago M.; Grant, Katherine; Mueller, Carsten W.; Lehmann, Johannes; Derry, Louis A.; Kögel-Knabner, Ingrid

    2017-04-01

    Volcanic Andosols are recognized by their strong capacity to accumulate soil organic carbon (SOC), and for presenting a singular aggregation pattern. However, the factors which govern their SOC storage and aggregation hierarchy are still poorly understood. In addition, many methods of fractionation are proposed for these soils and there is no consensus regarding the ideal methodology. In this way, the objective of this study was to evaluate the soil organic matter (SOM) properties of an Andosol through CN analysis, NMR spectroscopy, and Scanning electron microscopy (SEM) + NanoSIMS analysis in the soil mineral fraction testing different dispersion treatments. We tested three Andosol samples from two different sites of the Kohala region - Hawaii with contrasting precipitation levels. The samples tested were as follow: 1784-60 (altitude-average depth cm) and 1784-80: subsoil samples from 0.5-0.7 and 0.7-0.9 m depth, respectively, with annual mean precipitation of 1784 mm and altitude of 1194 m; and 2286-50: subsoil sample from 45-60 cm depth, with annual mean precipitation of 2286 mm and altitude of 1501 m. We performed the SOM fractionation using ultrasonic dispersion at 1500 J ml-1, wet sieving and sedimentation. Five fractions were obtained as follow: free particulate organic matter (fPOM), 4000-63, 63-20, 20-2 and analysis were carried out in the fraction analysis. More than 90% of the soil mass was concentrated in the fractions below 20 µm (i.e. 20-2 and analysis demonstrated distinct spatial differences in the distribution of 12C- and 12C14N- in organo-mineral associations at the micro scale between the two sites. The results of this study suggest that mineral interactions in the smaller size-fractions (<2µm) can be the key to explain the mechanisms of C storage in Andosols and that the pre-dispersion treatment with NaCL does not provide significant changes in the SOM study.

  13. Soil Organic Matter and Soil Productivity: Searching for the Missing Link

    Science.gov (United States)

    Felipe G. Sanchez

    1998-01-01

    Soil-organic matter (SOM) is a complex array of components including soil fauna and flora at different stages of decomposition (Berg et al., 1982). Its concentration in soils can vary from 0.5% in mineral soils to almost 100% in peat soils (Brady, 1974). Organic matter (OM) in the surface mineral soil is considered a major determinant of forest ecosystem productivity...

  14. Can particulate organic matter reveal emerging changes in soil organic carbon?

    DEFF Research Database (Denmark)

    Simonsson, Magnus; Kirchmann, Holger; Magid, Jakob

    2014-01-01

    different cropping systems, N fertilizer applications, and organic amendments, we found that C and N in the fine to medium sand fraction (0.063-0.600 mm, "Fraction B") showed considerably larger relative errors according to ANOVA (RMSE was 11-20% of the mean), slightly lower values of the F statistic......This study assessed whether particulate organic matter (POM) in sand fractions, isolated by wet sieving after treatment with Na hexametaphosphate, can be a sensitive indicator of incipient changes in the content and composition of soil organic matter. In five long-term field experiments including......, and slightly less contrast between treatments than total organic C and N (RMSE 3-9% of the mean). Imprecision in laboratory procedures only explained part of the increase in RMSE for C and N in Fraction B compared with total C and N; within-field spatial variability most likely had a greater influence...

  15. Characterization of extractable soil organic matter pools from African Dark Earths (AfDE): A case study in historical biochar and organic waste amendments

    Science.gov (United States)

    Fujiu, Manna; Plante, Alain; Ohno, Tsutomu; Solomon, Dawit; Lehmann, Johannes; Fraser, James; Leach, Melissa; Fairhead, James

    2014-05-01

    Anthropogenic Dark Earths are soils generated through long-term human inputs of organic and pyrogenic materials. These soils were originally discovered in the Amazon, and have since been found in Australia and in this case in Africa. African Dark Earths (AfDE) are black, highly fertile and carbon-rich soils that were formed from the original highly-weathered infertile yellowish to red Oxisols and Ultisols through an extant but hitherto overlooked climate-smart sustainable soil management system that has long been an important feature of the indigenous West African agricultural repertoire. Studies have demonstrated that ADE soils in general have significantly different organic matter properties compared to adjacent non-DE soils, largely attributable to the presence of high concentrations of ash-derived carbon. Quantification and characterization of bulk soil organic matter of several (n=11) AfDE and non-AfDE pairs of surface (0-15 cm) soils using thermal analysis techniques (TG-DSC-EGA) confirmed substantial differences in SOM composition and the presence of pyrogenic C. Such pyrogenic organic matter is generally considered recalcitrant or relatively stable, but the goal of the current study was to characterize the presumably labile, more rapidly cycling, pools of C in AfDEs through the characterization of hot water- and pyrophosphate-extractable fractions, referred to as HWEOC and PyroC respectively. Extracts were analyzed for carbon content, as well as composition using fluorescence (EEM/PARAFAC) and high resolution mass spectrometry (FTICR-MS). The amount of extractable C as a proportion of total soil C was relatively low: less than ~0.8% for HWEOC and 2.8% for PyroC. The proportion of HWEOC did not differ (P = 0.18, paired t-test) between the AfDE and the non-AfDE soils, while the proportions of PyroC were significantly larger (P = 0.001) in the AfDE soils compared to the non-AfDE soils. Preliminary analysis of the EEM/PARAFAC data suggests that AfDE samples had

  16. [Study on composite stabilization of arsenic (As) contaminated soil].

    Science.gov (United States)

    Wang, Hao; Pan, Li-xiang; Zhang, Xiang-yu; Li, Meng; Song, Bao-hua

    2013-09-01

    Since the contaminated soil may contain various kinds of heavy metals, use of single chemical reagent leads to poor remediation and high cost. In this study, soil containing As, Zn, Cd was sampled, and different reagents were selected to carry out the rapid stabilization of contaminated soil. The TCLP (toxicity characteristic leaching procedure) was used to evaluate the leachate toxicity of heavy metals and the results indicated that calcium-containing, sulphur-containing and iron-containing reagents had good performance in reducing the metal mobility. The stabilization efficiency of the six reagents tested ranked in the order of CaO > Na2S > organic sulfur > Chitosan > FeSO4 > (C2H5)2NCS2Na. Two types of reagents (six reagents) were combined based on the target properties of different reagents and the stabilization efficiency was evaluated and analyzed. The results indicated that the composite reagents had higher stabilization efficiency: the efficiency of 3% FeSO4 + 5% CaO was 81.7%, 97.2% and 68.2% for As, Cd and Zn, respectively, and the efficiency of 3% CaO + 5% organic sulfur was 76.6%, 95.7% and 93.8% for these three metals, respectively. Speciation analysis was carried out in this study and the results suggested that it was the change of metals from the exchangeable state to the reduction (for inorganic reagent) or oxidation state (for organic reagent) that caused the soil stabilization and the degree of change determined the stabilization efficiency.

  17. Alterations in soil microbial community composition and biomass following agricultural land use change.

    Science.gov (United States)

    Zhang, Qian; Wu, Junjun; Yang, Fan; Lei, Yao; Zhang, Quanfa; Cheng, Xiaoli

    2016-11-04

    The effect of agricultural land use change on soil microbial community composition and biomass remains a widely debated topic. Here, we investigated soil microbial community composition and biomass [e.g., bacteria (B), fungi (F), Arbuscular mycorrhizal fungi (AMF) and Actinomycete (ACT)] using phospholipid fatty acids (PLFAs) analysis, and basal microbial respiration in afforested, cropland and adjacent uncultivated soils in central China. We also investigated soil organic carbon and nitrogen (SOC and SON), labile carbon and nitrogen (LC and LN), recalcitrant carbon and nitrogen (RC and RN), pH, moisture, and temperature. Afforestation averaged higher microbial PLFA biomass compared with cropland and uncultivated soils with higher values in top soils than deep soils. The microbial PLFA biomass was strongly correlated with SON and LC. Higher SOC, SON, LC, LN, moisture and lower pH in afforested soils could be explained approximately 87.3% of total variation of higher total PLFAs. Afforestation also enhanced the F: B ratios compared with cropland. The basal microbial respiration was higher while the basal microbial respiration on a per-unit-PLFA basis was lower in afforested land than adjacent cropland and uncultivated land, suggesting afforestation may increase soil C utilization efficiency and decrease respiration loss in afforested soils.

  18. Divergent composition but similar function of soil food webs of individual plants

    DEFF Research Database (Denmark)

    Bezemer, T M; Fountain, M T; Barea, J M

    2010-01-01

    food webs were influenced both by the species identity of the plant individual and the surrounding plant community. Unexpectedly, plant identity had the strongest effects on decomposing soil organisms, widely believed to be generalist feeders. In contrast, quantitative food web modeling showed...... that the composition of the plant community influenced nitrogen mineralization under individual plants, but that plant species identity did not affect nitrogen or carbon mineralization or food web stability. Hence, the composition and structure of entire soil food webs vary at the scale of individual plants...... and are strongly influenced by the species identity of the plant. However, the ecosystem functions these food webs provide are determined by the identity of the entire plant community....

  19. Particulate organic carbon at reclaimed and unreclaimed post-mining soils and its microbial community composition

    Czech Academy of Sciences Publication Activity Database

    Bartuška, Martin; Pawlett, M.; Frouz, Jan

    2015-01-01

    Roč. 131, August (2015), s. 92-98 ISSN 0341-8162 Grant - others:GA ČR(CZ) GAP504/12/1288 Program:GA Institutional support: RVO:60077344 Keywords : soil organic matter * PLFA * chronosequence * succession * reclamation Subject RIV: DF - Soil Science Impact factor: 2.612, year: 2015

  20. Solubility of Benzo[a]pyrene and Organic Matter of Soil in Subcritical Water

    Directory of Open Access Journals (Sweden)

    Svetlana Sushkova

    2015-12-01

    Full Text Available A dynamic subcritical water extraction method of benzo[a]pyrene from soils is under consideration. The optimum conditions for benzo[a]pyrene extraction from soil are described including the soil treatment by subcritical water at 250 °C and 100 atm for 30 min. The effectiveness of developed method was determined using the matrix spiking recovery technique. A comparative analysis was made to evaluate the results of benzo[a]pyrene extraction from soils using the subcritical water and organic solvents. The advantages of the subcritical water extraction involve the use of ecologically friendly solvent, a shorter time for the analysis and a higher amount of benzo[a]pyrene extracted from soil (96 %. The influence of subcritical water extraction on soil properties was measured the investigation of the processes occurring within soil under the influence the high temperature and pressure. Under appropriate conditions of the experiment there is the destruction of the soil organic matter while the composition of the soil mineral fraction remains practically unchanged.

  1. Storage and turnover of organic matter in soil

    Energy Technology Data Exchange (ETDEWEB)

    Torn, M.S.; Swanston, C.W.; Castanha, C.; Trumbore, S.E.

    2008-07-15

    Historically, attention on soil organic matter (SOM) has focused on the central role that it plays in ecosystem fertility and soil properties, but in the past two decades the role of soil organic carbon in moderating atmospheric CO{sub 2} concentrations has emerged as a critical research area. This chapter will focus on the storage and turnover of natural organic matter in soil (SOM), in the context of the global carbon cycle. Organic matter in soils is the largest carbon reservoir in rapid exchange with atmospheric CO{sub 2}, and is thus important as a potential source and sink of greenhouse gases over time scales of human concern (Fischlin and Gyalistras 1997). SOM is also an important human resource under active management in agricultural and range lands worldwide. Questions driving present research on the soil C cycle include: Are soils now acting as a net source or sink of carbon to the atmosphere? What role will soils play as a natural modulator or amplifier of climatic warming? How is C stabilized and sequestered, and what are effective management techniques to foster these processes? Answering these questions will require a mechanistic understanding of how and where C is stored in soils. The quantity and composition of organic matter in soil reflect the long-term balance between plant carbon inputs and microbial decomposition, as well as other loss processes such as fire, erosion, and leaching. The processes driving soil carbon storage and turnover are complex and involve influences at molecular to global scales. Moreover, the relative importance of these processes varies according to the temporal and spatial scales being considered; a process that is important at the regional scale may not be critical at the pedon scale. At the regional scale, SOM cycling is influenced by factors such as climate and parent material, which affect plant productivity and soil development. More locally, factors such as plant tissue quality and soil mineralogy affect

  2. Effect of soil type and soil management on soil physical, chemical and biological properties in commercial organic olive orchards in Southern Spain

    Science.gov (United States)

    Gomez, Jose Alfonso; Auxiliadora Soriano, Maria; Montes-Borrego, Miguel; Navas, Juan Antonio; Landa, Blanca B.

    2014-05-01

    One of the objectives of organic agriculture is to maintain and improve soil quality, while simultaneously producing an adequate yield. A key element in organic olive production is soil management, which properly implemented can optimize the use of rainfall water enhancing infiltration rates and controlling competition for soil water by weeds. There are different soil management strategies: eg. weed mowing (M), green manure with surface tillage in spring (T), or combination with animal grazing among the trees (G). That variability in soil management combined with the large variability in soil types on which organic olive trees are grown in Southern Spain, difficult the evaluation of the impact of different soil management on soil properties, and yield as well as its interpretation in terms of improvement of soil quality. This communications presents the results and analysis of soil physical, chemical and biological properties on 58 soils in Southern Spain during 2005 and 2006, and analyzed and evaluated in different studies since them. Those 58 soils were sampled in 46 certified commercial organic olive orchards with four soil types as well as 12 undisturbed areas with natural vegetation near the olive orchards. The four soil types considered were Eutric Regosol (RGeu, n= 16), Eutric Cambisol (CMeu, n=16), Calcaric Regosol (RGca, n=13 soils sampled) and Calcic Cambisol (CMcc), and the soil management systems (SMS) include were 10 light tillage (LT), 16 sheep grazing (G), 10 tillage (T), 10 mechanical mowing (M), and 12 undisturbed areas covered by natural vegetation (NV-C and NV-S). Our results indicate that soil management had a significant effect on olive yield as well as on key soil properties. Among these soil properties are physical ones, such as infiltration rate or bulk density, chemical ones, especially organic carbon concentration, and biological ones such as soil microbial respiration and bacterial community composition. Superimpose to that soil

  3. Origin and fate of organic matter in sandy soils along a primary vegetation succession

    NARCIS (Netherlands)

    Nierop, K.

    1999-01-01

    Until now little is known about the role vegetation plays in the organic matter formation, particularly at the molecular level. Most ecosystems have a long history, which is unknown or too complex to find distinct relations between vegetation and the chemical composition of soil organic

  4. Decomposition of litter and soil organic matter - Can we distinguish a mechanism for soil organic matter buildup ?

    International Nuclear Information System (INIS)

    Berg, B.; Johansson, M.B.; McClaugherty, C.; Virzo de Santo, A.; Ekbohm, G.

    1995-01-01

    This synthesis paper presents a model for estimating the buildup of soil organic matter in various types of coniferous forests. The knowledge used was obtained from a well-studied forest with good litterfall data, decomposition information and validation measurements of the soil organic matter layer. By constructing a simple model for litterfall, and the information on maximum decomposition levels for litter, we could estimate the annual increase in soil organic matter and extend this to encompass stand age. The validation measurement and the estimated amount of soil organic matter differed by about 8 or 26% over a 120-yr period, depending on the litterfall model. The estimated increased storage of soil organic matter as a consequence of climate change was found to be drastic. We thus found that the soil organic matter layer would grow about four times as fast as a result of the needle component only. This estimate was based on a comparison between latitudes with a difference of 17 degrees. 35 refs, 7 figs, 3 tabs

  5. Plant litter chemistry alters the content and composition of organic carbon associated with soil mineral and aggregate fractions in invaded ecosystems.

    Science.gov (United States)

    Tamura, Mioko; Suseela, Vidya; Simpson, Myrna; Powell, Brian; Tharayil, Nishanth

    2017-10-01

    Through the input of disproportionate quantities of chemically distinct litter, invasive plants may potentially influence the fate of organic matter associated with soil mineral and aggregate fractions in some of the ecosystems they invade. Although context dependent, these native ecosystems subjected to prolonged invasion by exotic plants may be instrumental in distinguishing the role of plant-microbe-mineral interactions from the broader edaphic and climatic influences on the formation of soil organic matter (SOM). We hypothesized that the soils subjected to prolonged invasion by an exotic plant that input recalcitrant litter (Japanese knotweed, Polygonum cuspidatum) would have a greater proportion of plant-derived carbon (C) in the aggregate fractions, as compared with that in adjacent soil inhabited by native vegetation that input labile litter, whereas the soils under an invader that input labile litter (kudzu, Pueraria lobata) would have a greater proportion of microbial-derived C in the silt-clay fraction, as compared with that in adjacent soils that receive recalcitrant litter. At the knotweed site, the higher C content in soils under P. cuspidatum, compared with noninvaded soils inhabited by grasses and forbs, was limited to the macroaggregate fraction, which was abundant in plant biomarkers. The noninvaded soils at this site had a higher abundance of lignins in mineral and microaggregate fractions and suberin in the macroaggregate fraction, partly because of the greater root density of the native species, which might have had an overriding influence on the chemistry of the above-ground litter input. At the kudzu site, soils under P. lobata had lower C content across all size fractions at a 0-5 cm soil depth despite receiving similar amounts of Pinus litter. Contrary to our prediction, the noninvaded soils receiving recalcitrant Pinus litter had a similar abundance of plant biomarkers across both mineral and aggregate fractions, potentially because of

  6. [Effects of variable temperature on organic carbon mineralization in typical limestone soils].

    Science.gov (United States)

    Wang, Lian-Ge; Gao, Yan-Hong; Ding, Chang-Huan; Ci, En; Xie, De-Ti

    2014-11-01

    Soil sampling in the field and incubation experiment in the laboratory were conducted to investigate the responses of soil organic carbon (SOC) mineralization to variable temperature regimes in the topsoil of limestone soils from forest land and dry land. Two incubated limestone soils were sampled from the 0-10 cm layers of typical forest land and dry land respectively, which were distributed in Tianlong Mountain area of Puding county, Guizhou province. The soils were incubated for 56 d under two different temperature regimes including variable temperature (range: 15-25 degrees C, interval: 12 h) and constant temperature (20 degrees C), and the cumulative temperature was the same in the two temperature treatments. In the entire incubation period (56 d), the SOC cumulative mineralization (63.32 mg x kg(-1)) in the limestone soil from dry land (SH) under the variable temperature was lower than that (63.96 mg x kg(-1)) at constant 20 degrees C, and there was no significant difference in the SOC cumulative mineralization between the variable and constant temperature treatments (P variable temperature was significantly lower than that (209.52 mg x kg(-1)) at constant 20 degrees C. The results indicated that the responses of SOC mineralization to the variable temperature were obviously different between SL and SH soils. The SOC content and composition were significantly different between SL and SH soils affected by vegetation and land use type, which suggested that SOC content and composition were important factors causing the different responses of SOC mineralization to variable temperature between SL and SH soils. In addition, the dissolved organic carbon (DOC) content of two limestone soils were highly (P variable temperature mainly influenced SOC mineralization by changing microbial community activity rather than by changing microbial quantity.

  7. Characterizing the release of different composition of dissolved organic matter in soil under acid rain leaching using three-dimensional excitation-emission matrix spectroscopy.

    Science.gov (United States)

    Liu, Li; Song, Cunyi; Yan, Zengguang; Li, Fasheng

    2009-09-01

    Although excitation-emission matrix spectroscopy (EEMS) has been widely used to characterize dissolved organic matter (DOM), there has no report that EEMS has been used to study the effects of acid rain on DOM and its composition in soil. In this work, we employed three-dimensional EEMS to characterize the compositions of DOM leached by simulated acid rain from red soil. The red soil was subjected to leaching of simulated acid rain of different acidity, and the leached DOM presented five main peaks in its EEMS: peak-A, related to humic acid-like (HA-like) material, at Ex/Em of 310-330/395-420nm; peak-B, related to UV fulvic acid-like (FA-like) material, at Ex/Em of 230-280/400-435nm; peak-C and peak-D, both related to microbial byproduct-like material, at Ex/Em of 250-280/335-355nm and 260-280/290-320nm, respectively; and peak-E, related to simple aromatic proteins, at Ex/Em of 210-240/290-340nm. EEMS analysis results indicated that most DOM could be lost from red soil in the early phase of acid rain leaching. In addition to the effects of the pH of acid rain, the loss of DOM also depended on the properties of its compositions and the solubility of their complexes with aluminum. HA-like and microbial byproduct-like materials could be more easily released from red soil by acid rain at both higher pH (4.5 and 5.6) and lower pH (2.5 and 3) than that at middle pH (3.5). On the contrary, FA-like material lost in a similar manner under the action of different acid rains with pH ranging from 2.5 to 5.6.

  8. [Effects of different cultivation patterns on soil aggregates and organic carbon fractions].

    Science.gov (United States)

    Qiu, Xiao-Lei; Zong, Liang-Gang; Liu, Yi-Fan; Du, Xia-Fei; Luo, Min; Wang, Run-Chi

    2015-03-01

    Combined with the research in an organic farm in the past 10 years, differences of soil aggregates composition, distribution and organic carbon fractions between organic and conventional cultivation were studied by simultaneous sampling analysis. The results showed that the percentages of aggregates (> 1 mm, 1-0.5 mm, 0.5-0.25 mm and organic cultivation were 9.73%, 18.41%, 24.46% and 43.90%, respectively. The percentage of organic cultivation than that in conventional cultivation. Organic cultivation increased soil organic carbon (average of 17.95 g x kg(-1)) and total nitrogen contents (average of 1.51 g x kg(-1)). Among the same aggregates in organic cultivation, the average content of heavy organic carbon fraction was significantly higher than that in conventional cultivation. This fraction accumulated in organic carbon. In organic cultivation, the content of labile organic carbon in > 1 mm macro-aggregates was significantly higher than that in conventional cultivation, while no significant difference was found among the other aggregates, indicating that the labile organic carbon was enriched in > 1 mm macro-aggregates. Organic cultivation increased the amounts of organic carbon and its fractions, reduced tillage damage to aggregates, and enhanced the stability of organic carbon. Organic cultivation was therefore beneficial for soil carbon sequestration. The findings of this research may provide theoretical basis for further acceleration of the organic agriculture development.

  9. Base-line data on everglades soil-plant systems: elemental composition, biomass, and soil depth

    International Nuclear Information System (INIS)

    Volk, B.G.; Schemnitz, S.D.; Gamble, J.F.; Sartain, J.B.

    1975-01-01

    Plants and soils from plots in the Everglades Wildlife Management Area, Conservation Area 3, were examined. Chemical composition (N, P, K, Ca, Mg, Na, Cu, Fe, Mn, Zn, Co, Sr, Pb, Ni, Cr, Al, and Si) of most plant and soil digests was determined. Cladium jamaicense was the predominant plant species contributing to biomass in all plots except the wet prairie, where Rhynchospora sp. and Panicum hemitomon were most common. The biomass of dead C. jamaicense was greater than that of the living plants in unburned saw-grass plots. The burned saw grass, muck burn, and wet prairie were characterized by a large number of plant species per square meter but smaller average biomass production than the unburned saw-grass locations. Levels of Cu, Mn, Ca, Mg, K, and N in C. jamaicense differed significantly across locations. Highly significant differences in elemental composition existed between plant species. Concentrations of several elements (particularly Zn, Ca, Mg, P, and N) were low in live C. jamaicense compared with other plant species. Cesium-137 levels ranged from 670 to 3100 pCi/kg in sandy and in organic soils, respectively. Polygonum had a 137 Cs level of 11,600 pCi/kg. Dead C. jamaicense indicated a rapid leaching loss of 137 Cs from dead tissue

  10. How do peat type, sand addition and soil moisture influence the soil organic matter mineralization in anthropogenically disturbed organic soils?

    Science.gov (United States)

    Säurich, Annelie; Tiemeyer, Bärbel; Don, Axel; Burkart, Stefan

    2017-04-01

    Drained peatlands are hotspots of carbon dioxide (CO2) emissions from agriculture. As a consequence of both drainage induced mineralization and anthropogenic sand mixing, large areas of former peatlands under agricultural use contain soil organic carbon (SOC) at the boundary between mineral and organic soils. Studies on SOC dynamics of such "low carbon organic soils" are rare as the focus of previous studies was mainly either on mineral soils or "true" peat soil. However, the variability of CO2 emissions increases with disturbance and therefore, we have yet to understand the reasons behind the relatively high CO2 emissions of these soils. Peat properties, soil organic matter (SOM) quality and water content are obviously influencing the rate of CO2 emissions, but a systematic evaluation of the hydrological and biogeochemical drivers for mineralization of disturbed peatlands is missing. With this incubation experiment, we aim at assessing the drivers of the high variability of CO2 emissions from strongly anthropogenically disturbed organic soil by systematically comparing strongly degraded peat with and without addition of sand under different moisture conditions and for different peat types. The selection of samples was based on results of a previous incubation study, using disturbed samples from the German Agricultural Soil Inventory. We sampled undisturbed soil columns from topsoil and subsoil (three replicates of each) of ten peatland sites all used as grassland. Peat types comprise six fens (sedge, Phragmites and wood peat) and four bogs (Sphagnum peat). All sites have an intact peat horizon that is permanently below groundwater level and a strongly disturbed topsoil horizon. Three of the fen and two of the bog sites have a topsoil horizon altered by sand-mixing. In addition the soil profile was mapped and samples for the determination of soil hydraulic properties were collected. All 64 soil columns (including four additional reference samples) will be installed

  11. Study on the effect of organic fertilizers on soil organic matter and enzyme activities of soil in forest nursery

    Directory of Open Access Journals (Sweden)

    Piaszczyk Wojciech

    2017-09-01

    Full Text Available The aim of the study was to assess the effects of organic fertilization on selected chemical properties of the soil and the activity of dehydrogenase and β-glucosidase in the soil of forest nursery. The main goal was to evaluate the role of organic fertilizers in carbon storage in the forest nursery soil. Sample plots were located in northern Poland in the Polanów Forest District on a forest nursery. Soil samples were collected from horizon 0–20 cm for laboratory analyzes. In soil samples pH, soil texture, and organic carbon, nitrogen, base cation contents, dehydrogenase activity and β-glucosidase activity were determined. The obtained results were used to evaluate the carbon storage. The results confirm the beneficial effect of the applied organic fertilizer on chemical properties of the soils under study and their biological activity. The applied organic fertilizers had an impact on increased accumulation of soil organic matter. In the soils investigated, there was an increase in the activity of such enzymes as dehydrogenases and β-glucosidase.

  12. Mechanical properties of soil buried kenaf fibre reinforced thermoplastic polyurethane composites

    International Nuclear Information System (INIS)

    Sapuan, S.M.; Pua, Fei-ling; El-Shekeil, Y.A.; AL-Oqla, Faris M.

    2013-01-01

    Highlights: • We developed composites from kenaf and thermoplastic polyurethane. • Soil burial of composites after 80 days shows increase in flexural strength. • Soil burial of composites after 80 days shows increase in flexural modulus. • Tensile properties of composites degrade after soil burial tests. • We investigate the morphological fracture through scanning electron microscopy. - Abstract: A study on mechanical properties of soil buried kenaf fibre reinforced thermoplastic polyurethane (TPU) composites is presented in this paper. Kenaf bast fibre reinforced TPU composites were prepared via melt-mixing method using Haake Polydrive R600 internal mixer. The composites with 30% fibre loading were prepared based on some important parameters; i.e. 190 °C for reaction temperature, 11 min for reaction time and 400 rpm for rotating speed. The composites were subjected to soil burial tests where the purpose of these tests was to study the effect of moisture absorption on the mechanical properties of the composites. Tensile and flexural properties of the composites were determined before and after the soil burial tests for 20, 40, 60 and 80 days. The percentages of both moisture uptake and weight gain after soil burial tests were recorded. Tensile strength of kenaf fibre reinforced TPU composite dropped to ∼16.14 MPa after 80 days of soil burial test. It was also observed that there was no significant change in flexural properties of soil buried kenaf fibre reinforced TPU composite specimens

  13. An ecosystem approach to assess soil quality in organically and conventionally managed farms in Iceland and Austria

    Science.gov (United States)

    van Leeuwen, J. P.; Lehtinen, T.; Lair, G. J.; Bloem, J.; Hemerik, L.; Ragnarsdóttir, K. V.; Gísladóttir, G.; Newton, J. S.; de Ruiter, P. C.

    2015-01-01

    Intensive agricultural production can be an important driver for the loss of long-term soil quality. For this reason, the European Critical Zone Observatory (CZO) network adopted four pairs of agricultural CZO sites that differ in their management: conventional or organic. The CZO sites include two pairs of grassland farms in Iceland and two pairs of arable farms in Austria. Conventional fields differed from the organic fields in the use of artificial fertilisers and pesticides. Soils of these eight farms were analysed in terms of their physical, chemical, and biological properties, including soil aggregate size distribution, soil organic matter contents, abundance of soil microbes and soil fauna, and taxonomic diversity of soil microarthropods. In Icelandic grasslands, organically farmed soils had larger mean weight diameters of soil aggregates than the conventional farms, while there were no differences on the Austrian farms. Organic farming did not systematically influence organic matter contents or composition, nor soil carbon and nitrogen contents. Also, soil food web structures, in terms of presence of trophic groups of soil organisms, were highly similar among all farms, indicating a low sensitivity of trophic structure to land use or climate. However, soil organism biomass, especially of bacteria and nematodes, was consistently higher on organic farms than on conventional farms. Within the microarthropods, taxonomic diversity was systematically higher in the organic farms compared to the conventional farms. This difference was found across countries and farm, crop, and soil types. The results do not show systematic differences in physical and chemical properties between organic and conventional farms, but confirm that organic farming can enhance soil biomass and that microarthropod diversity is a sensitive and consistent indicator for land management.

  14. Estimating the Pollution Risk of Cadmium in Soil Using a Composite Soil Environmental Quality Standard

    Science.gov (United States)

    Huang, Biao; Zhao, Yongcun

    2014-01-01

    Estimating standard-exceeding probabilities of toxic metals in soil is crucial for environmental evaluation. Because soil pH and land use types have strong effects on the bioavailability of trace metals in soil, they were taken into account by some environmental protection agencies in making composite soil environmental quality standards (SEQSs) that contain multiple metal thresholds under different pH and land use conditions. This study proposed a method for estimating the standard-exceeding probability map of soil cadmium using a composite SEQS. The spatial variability and uncertainty of soil pH and site-specific land use type were incorporated through simulated realizations by sequential Gaussian simulation. A case study was conducted using a sample data set from a 150 km2 area in Wuhan City and the composite SEQS for cadmium, recently set by the State Environmental Protection Administration of China. The method may be useful for evaluating the pollution risks of trace metals in soil with composite SEQSs. PMID:24672364

  15. Comparing organic versus conventional soil management on soil respiration [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Bence Mátyás

    2018-03-01

    Full Text Available Soil management has great potential to affect soil respiration. In this study, we investigated the effects of organic versus conventional soil management on soil respiration.  We measured the main soil physical-chemical properties from conventional and organic managed soil in Ecuador. Soil respiration was determined using alkaline absorption according to Witkamp.  Soil properties such as organic matter, nitrogen, and humidity, were comparable between conventional and organic soils in the present study, and in a further analysis there was no statically significant correlation with soil respiration. Therefore, even though organic farmers tend to apply more organic material to their fields, but this did not result in a significantly higher CO2 production in their soils in the present study.

  16. Linking the Composition of Bacterial and Archaeal Communities to Characteristics of Soil and Flora Composition in the Atlantic Rainforest.

    Science.gov (United States)

    Lima-Perim, Julia Elidia; Romagnoli, Emiliana Manesco; Dini-Andreote, Francisco; Durrer, Ademir; Dias, Armando Cavalcante Franco; Andreote, Fernando Dini

    2016-01-01

    The description of microbiomes as intrinsic fractions of any given ecosystem is an important issue, for instance, by linking their compositions and functions with other biotic and abiotic components of natural systems and hosts. Here we describe the archaeal and bacterial communities from soils of the Atlantic Rainforest in Brazil. Based on the comparison of three areas located along an altitudinal gradient-namely, Santa Virginia, Picinguaba and Restinga-we detected the most abundant groups of Bacteria (Acidobacteria and Proteobacteria) and Archaea (Thaumarchaeota, Crenarchaeota and Euryarchaeota). The particular composition of such communities in each of these areas was first evidenced by PCR-DGGE patterns [determined for Bacteria, Archaea and ammonia-oxidizing organisms-ammonia-oxidizing archaea (AOA) and bacteria (AOB)]. Moreover, sequence-based analysis provided a better resolution of communities, which indicated distinct frequencies of archaeal phyla and bacterial OTUs across areas. We found, as indicated by the Mantel test and multivariate analyses, a potential effect of the flora composition that outpaces the effect of soil characteristics (either physical and chemical) influencing the assembly of these microbial communities in soils. Our results indicate a collective role of the ecosystem underlying observed differences in microbial communities in these soils. Particularly, we posit that rainforest preservation also needs to take into account the maintenance of the soil biodiversity, as this is prompted to influence major processes that affect ecosystem functioning.

  17. Effect of the cationic composition of sorption solution on the quantification of sorption-desorption parameters of heavy metals in soils

    International Nuclear Information System (INIS)

    Sastre, J.; Rauret, G.; Vidal, M.

    2006-01-01

    We obtained the sorption isotherms of Cd, Cu, Pb and Zn in clay, clay saline and organic soils. The distribution coefficients (K d ) were determined in 0.02 eq l -1 CaCl 2 and in a solution that simulated the soil solution cationic composition. The K d values greatly varied with the composition of the sorption solution and the initial metal concentration. The sorption experiments were complemented with the quantification of the extractable metal, to estimate the reversibility of metal sorption. The extraction yields depended on the metal-soil combination, and the initial metal concentration, showing no correlation with previous K d values. The effect of the solution composition in mobility predictions was estimated through a Retention Factor, defined as the ratio of the K d versus the extraction yield. Results showed that risk was over- or underestimated using the CaCl 2 medium in soils with a markedly different soil solution composition. - Sorption solution composition modifies metal sorption-desorption pattern in soils

  18. Use of high-dimensional spectral data to evaluate organic matter, reflectance relationships in soils

    Science.gov (United States)

    Henderson, T. L.; Baumgardner, M. F.; Coster, D. C.; Franzmeier, D. P.; Stott, D. E.

    1990-01-01

    Recent breakthroughs in remote sensing technology have led to the development of a spaceborne high spectral resolution imaging sensor, HIRIS, to be launched in the mid-1990s for observation of earth surface features. The effects of organic carbon content on soil reflectance over the spectral range of HIRIS, and to examine the contributions of humic and fulvic acid fractions to soil reflectance was evaluated. Organic matter from four Indiana agricultural soils was extracted, fractionated, and purified, and six individual components of each soil were isolated and prepared for spectral analysis. The four soils, ranging in organic carbon content from 0.99 percent, represented various combinations of genetic parameters such as parent material, age, drainage, and native vegetation. An experimental procedure was developed to measure reflectance of very small soil and organic component samples in the laboratory, simulating the spectral coverage and resolution of the HIRIS sensor. Reflectance in 210 narrow (10 nm) bands was measured using the CARY 17D spectrophotometer over the 400 to 2500 nm wavelength range. Reflectance data were analyzed statistically to determine the regions of the reflective spectrum which provided useful information about soil organic matter content and composition. Wavebands providing significant information about soil organic carbon content were located in all three major regions of the reflective spectrum: visible, near infrared, and middle infrared. The purified humic acid fractions of the four soils were separable in six bands in the 1600 to 2400 nm range, suggesting that longwave middle infrared reflectance may be useful as a non-destructive laboratory technique for humic acid characterization.

  19. Influence of Organic Manure on Organic Phosphorus Fraction in Soils

    Institute of Scientific and Technical Information of China (English)

    ZHANGYONG-SONG; NIWU-ZHONG; 等

    1993-01-01

    The transformation of organic P(Po) from organic manures in two types of soils (ultisol and entisol) and the influences of external addition of organic substance or inorganic P(Pi) on Po under the condition of the 60% maximum water capacity were investigated.The results obtained from Po fractionation experiments indicated that all the Po fractions except for the highly resistant Po fraction decreased during incubation.Application of pig feces and cow feces could largely increase each fraction of Po in the soils.Immediately after application of organic manure into the soils a large part of labile and moderately labile Po from organic manure was transferred into moderately resistant Po,which might be due to the fact that Ca-or Mg-inositol P was precipitated into Fe-inositol P.However,the availability of Po from organic manure in the soils would increase again after incubation because of the transformation of moderately labile and resistant Po fractions into labile Po fractions.Addition of cellulose or Pi into the soils showed a good effect on increasing all the Po fractions except for the highly resistant Po,and this effect was much more pronounced when cellulose was applied in combination with Pi.Therefore,in view of the effect of organic manure on improving P nutrition to plant,attention should be paid to both the Po and the organic substances from organic manure,It is suggested that application of Pi fertilizer combined with organic manure may be referred to as an effective means of protecting Pi from chemical fixation in soil.

  20. Solid-state 13C NMR experiments reveal effects of aggregate size on the chemical composition of particulate organic matter in grazed steppe soils

    Science.gov (United States)

    Steffens, M.; Kölbl, A.; Kögel-Knabner, I.

    2009-04-01

    Grazing is one of the most important factors that may reduce soil organic matter (SOM) stocks and subsequently deteriorate aggregate stability in grassland topsoils. Land use management and grazing reduction are assumed to increase the input of OM, improve the soil aggregation and change species composition of vegetation (changes depth of OM input). Many studies have evaluated the impact of grazing cessation on SOM quantity. But until today little is known about the impact of grazing cessation on the chemical quality of SOM in density fractions, aggregate size classes and different horizons. The central aim of this study was to analyse the quality of SOM fractions in differently sized aggregates and horizons as affected by increased inputs of organic matter due to grazing exclusion. We applied a combined aggregate size, density and particle size fractionation procedure to sandy steppe topsoils with different organic matter inputs due to different grazing intensities (continuously grazed = Cg, winter grazing = Wg, ungrazed since 1999 = Ug99, ungrazed since 1979 = Ug79). Three different particulate organic matter (POM; free POM, in aggregate occluded POM and small in aggregate occluded POM) and seven mineral-associated organic matter fractions were separated for each of three aggregate size classes (coarse = 2000-6300 m, medium = 630-2000 m and fine =

  1. Climate-related changes of soil characteristics affect bacterial community composition and function of high altitude and latitude lakes.

    Science.gov (United States)

    Rofner, Carina; Peter, Hannes; Catalán, Núria; Drewes, Fabian; Sommaruga, Ruben; Pérez, María Teresa

    2017-06-01

    Lakes at high altitude and latitude are typically unproductive ecosystems where external factors outweigh the relative importance of in-lake processes, making them ideal sentinels of climate change. Climate change is inducing upward vegetation shifts at high altitude and latitude regions that translate into changes in the pools of soil organic matter. Upon mobilization, this allochthonous organic matter may rapidly alter the composition and function of lake bacterial communities. Here, we experimentally simulate this potential climate-change effect by exposing bacterioplankton of two lakes located above the treeline, one in the Alps and one in the subarctic region, to soil organic matter from below and above the treeline. Changes in bacterial community composition, diversity and function were followed for 72 h. In the subarctic lake, soil organic matter from below the treeline reduced bulk and taxon-specific phosphorus uptake, indicating that bacterial phosphorus limitation was alleviated compared to organic matter from above the treeline. These effects were less pronounced in the alpine lake, suggesting that soil properties (phosphorus and dissolved organic carbon availability) and water temperature further shaped the magnitude of response. The rapid bacterial succession observed in both lakes indicates that certain taxa directly benefited from soil sources. Accordingly, the substrate uptake profiles of initially rare bacteria (copiotrophs) indicated that they are one of the main actors cycling soil-derived carbon and phosphorus. Our work suggests that climate-induced changes in soil characteristics affect bacterioplankton community structure and function, and in turn, the cycling of carbon and phosphorus in high altitude and latitude aquatic ecosystems. © 2016 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

  2. Distribution of transformed organic matter in structural units of loamy sandy soddy-podzolic soil

    Science.gov (United States)

    Kogut, B. M.; Yashin, M. A.; Semenov, V. M.; Avdeeva, T. N.; Markina, L. G.; Lukin, S. M.; Tarasov, S. I.

    2016-01-01

    The effect of land use types and fertilizing systems on the structural and aggregate composition of loamy sandy soddy-podzolic soil and the quantitative parameters of soil organic matter has been studied. The contribution of soil aggregates 2-1 mm in size to the total Corg reserve in the humus horizon is higher than the contributions of other aggregates by 1.3-4.2 times. Reliable correlations have been revealed between the contents of total (Corg), labile (Clab), and active (C0) organic matter in the soil. The proportion of C0 is 44-70% of Clab extractable by neutral sodium pyrophosphate solution. The contributions of each of the 2-1, 0.5-0.25, and fractions to the total C0 reserve are 14-21%; the contributions of each of the other fractions are 4-12%. The chemically labile and biologically active components of humic substances reflect the quality changes of soil organic matter under agrogenic impacts. A conceptual scheme has been proposed for the subdivision of soil organic matter into the active, slow (intermediate), and passive pools. In the humus horizon of loamy sandy soddy-podzolic soil, the active, slow, and passive pools contain 6-11, 34-65, and 26-94% of the total Corg, respectively.

  3. Organic matter in constructed soils from a coal mining area in southern Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Dick, Deborah P.; Avila, Leticia G. [Universidade Federal do Rio Grande do Sul, Inst. de Quimica, Porto Alegre, RS (Brazil); Knicker, Heike [Technische Universitaet Muenchen, Lehrstuhl fuer Bodenkunde, Freising-Weihenstephan (Germany); Inda, Alberto V. Jr.; Giasson, Elvio; Bissani, Carlos A. [Universidade Federal do Rio Grande do Sul, Dept. de Ciencia do Solo, Porto Alegre, RS (Brazil)

    2006-11-15

    In southern Brazil, the landscape restoration after the exhaustion of open cast coal mines involves the filling of mine cavities with both pedogenic and geological material. The objective of this work was to determine the content and chemical composition of the organic matter of two constructed soils (24 years and 2 years) in a coal mining area in southern Brazil. An undisturbed Acrisol and geological material from three sites were also sampled. Samples were analyzed for carbon and nitrogen contents by dry combustion and for chemical composition of the organic matter by {sup 13} C NMR CPMAS and FTIR spectroscopies. Prior to the spectroscopic analyses, the samples were treated with 10% (m/m) hydrofluoric acid solution, which lead to a carbon enrichment in the sample of 2-46 times. The three coal samples were mainly composed of aromatic C (46-63%) and alkyl C (10-28%), and differed largely in the carbon content (18-312 g kg{sup -1}). The C/N ratio of 27 and the proportions of O-alkyl C (26%) and aromatic C (29%) found in the native soil (18 g C kg{sup -1} soil) suggest a coal contamination of the native site. The proportions of O/N-alkyl C (15-17%), alkyl C (22-23%) and aromatic C (39-41%) observed in the organic matter of the A1 horizon of the two constructed soils were intermediate to those of the coal samples and the native soil. In the younger constructed soil the proportion of O/N-alkyl diminished and that of aromatic C increased with depth, whereas in the older constructed soil this trend was less evident. Our results show that, during the 24 years after site reconstruction, the input of vegetation residues diluted the proportion of recalcitrant organic matter. The aromaticity index calculated from the FTIR data (I{sub 1620} /I{sub 2920}) correlated positively with the aryl C/alkyl C ratio, obtained from the NMR data, evidencing the applicability of the FTIR index for geological and coal contaminated samples. (Author)

  4. Radiocarbon enrichment of soil organic matter fractions in New Zealand soils

    International Nuclear Information System (INIS)

    Goh, K.M.; Stout, J.D.; Rafter, T.A.

    1977-01-01

    Soil organic matter was extracted using the classical procedure and fractionated into humin (nonextractable), humic acid, and fulvic acid. The masses of total organic carbon in the whole soil samples and in the fractions, together with their 14 C content and 13 C/ 12 C ratios, were also determined. The following New Zealand soils were studied: a Fluvaquent, with experimental pasture plots, formed from deeply mixing subsoils of low organic carbon content; a Typic Fragiaqualf and a Typic Dystrochrept with moderately productive pastures; and an Umbric Vitrandept at two sites under native tussock and under introduced grasses of low productivity. The degree of radiocarbon enrichment of the different fractions in both topsoil and subsoil samples was examined in relation to differences in soil type, soil biological activity, and vegetation history. There was variation in the distribution and enrichment of the organic matter fractions both within the same soil type and between soil types, as well as between the topsoil and subsoil of the same soil. Differences appeared to be primarily a function of the stage of decomposition and translocation of the fractions through the soil rather than due to vegetation differences

  5. Distribution of some organic components in two forest soils profiles with evidence of soil organic matter leaching.

    Science.gov (United States)

    Álvarez-Romero, Marta; Papa, Stefania; Lozano-García, Beatriz; Parras-Alcántara, Luis; Coppola, Elio

    2015-04-01

    Soil stores organic carbon more often than we can find in living vegetation and atmosphere together. This reservoir is not inert, but it is constantly in a dynamic phase of inputs and losses. Soil organic carbon mainly depends on land cover, environment conditions and soil properties. After soil deposition, the organic residues of different origin and nature, the Soil Organic Matter (SOM) can be seen involved in two different processes during the pedogenesis: mineralization and humification. The transport process along profile happens under certain conditions such as deposition of high organic residues amount on the top soil, high porosity of the soil caused by sand or skeleton particles, that determine a water strong infiltrating capacity, also, extreme temperatures can slow or stop the mineralization and/or humification process in one intermediate step of the degradation process releasing organic metabolites with high or medium solubility and high loads of water percolating in relation to intense rainfall. The transport process along soil profile can take many forms that can end in the formation of Bh horizons (h means accumulation of SOM in depth). The forest cover nature influence to the quantity and quality of the organic materials deposited with marked differences between coniferous and deciduous especially in relation to resistance to degradation. Two soils in the Campania region, located in Lago Laceno (Avellino - Italy) with different forest cover (Pinus sp. and Fagus sp.) and that meets the requirements of the place and pedological formation suitable for the formation and accumulation of SOM in depth (Bh horizon) were studied. The different soil C fractions were determinated and were assessed (Ciavatta C. et al. 1990; Dell'Abate M.T. et al. 2002) for each soil profile the Total Extractable Lipids (TEL). Furthermore, the lignin were considered as a major component of soil organic matter (SOM), influencing its pool-size and its turnover, due to the high

  6. The influence of different concentrations of bio-organic fertilizer on cucumber Fusarium wilt and soil microflora alterations.

    Directory of Open Access Journals (Sweden)

    Nan Huang

    Full Text Available Fusarium wilt is one of the main diseases of cucumber, and bio-organic fertilizer has been used to control Fusarium wilt. In this study, a pot experiment was conducted to evaluate the effects of bio-organic fertilizer applied at four levels on the suppression of Fusarium wilt disease in cucumber, the soil physico-chemical properties and the microbial communities. In comparison with the control (CK, low concentrations of bio-organic fertilizer (BIO2.5 and BIO5 did not effectively reduce the disease incidence and had little effect on soil microorganisms. High concentrations of bio-organic fertilizer (BIO10 and BIO20 significantly reduced the disease incidence by 33.3%-66.7% and the production was significantly improved by 83.8%-100.3%. The soil population of F. oxysporum f. sp. cucumerinum was significantly lower in bio-organic fertilizer treatments, especially in BIO10 and BIO20. The microorganism activity increased with the bio-organic fertilizer concentration. High-throughput sequencing demonstrated that, at the order level, Sphingomonadales, Bacillales, Solibacterales and Xylariales were significantly abundant in BIO10 and BIO20 soils. At the genus level, the abundance and composition of bacterial and fungal communities in BIO10 and BIO20 were similar, illustrating that high concentrations of bio-organic fertilizer activated diverse groups of microorganisms. Redundancy analysis (RDA showed that Xanthomonadales, Sphingomonadales, Bacillales, Orbiliales, Sordariales, and Mucorales occurred predominantly in the BIO10 and BIO20. These microorganisms were related to the organic matter, available potassium and available phosphorus contents. In conclusion, a high concentration of bio-organic fertilizer application suppressed the Fusarium wilt disease and increased cucumber production after continuous cropping might through improving soil chemical condition and manipulating the composition of soil microbial community.

  7. STUDY ON MICROBIAL COMMUNITIES AND SOIL ORGANIC MATTER IN IRRIGATED AND NON-IRRIGATED VERTISOL FROM BOIANU

    Directory of Open Access Journals (Sweden)

    Sorina Dumitru

    2012-12-01

    Full Text Available Irrigation, when administered correctly, confers the producers the possibility to overcome drought effects and obtain higher yields, supplementing the quality of food for animals or human consumers. In the mean time, soil erosion, pathogens attack and nutrients or pesticides spreading can be prevented by an adequate management of irrigation water. As a consequence, soil microbial community structure, composition and activities, as well as the organic matter quality can be different from those in non-irrigated soil. Research have been carried out in order to assess changes in bacterial and fungal communities and activity in irrigated Vertisol from Boianu, as compared with non-irrigated. The paper presents the results concerning the taxonomical composition of bacterial and fungalmicroflora in the horizons of the two soil profiles, as well as the level of CO2 released by microorganisms. Chromatographic aspects of humus fractions were used to characterize the organic matter in irrigated and nonirrigated soil. Increased moisture and lowered temperature in Ap horizon of irrigated soil increased bacterial counts(18 x106 viable cells x g-1 dry soil and their metabolic activity expressed by carbon dioxide released (46.838mg CO2 x g-1 dry soil comparatively with non- irrigated soil. Fungal microflora was more abundant after 25-50cm under irrigation. Species diversity slightly increased under irrigation in both upper and lower part of soil profile. In irrigated soil, associations of species belonging to bacterial genera Pseudomonas and Bacillus were dominant in surface and white actinomycetes in the depth. Fungal consortia of Penicillium, Aspergillus and Fusarium dominated in both soil profiles.Irrigation induced changes in the quantity and quality of soil organic matter, as well as in the aspect of their migration pattern, as revealed on circular chromatograms.

  8. Soil factors involved in the diversity and structure of soil bacterial communities in commercial organic olive orchards in Southern Spain.

    Science.gov (United States)

    Landa, B B; Montes-Borrego, M; Aranda, S; Soriano, M A; Gómez, J A; Navas-Cortés, J A

    2014-04-01

    Nowadays, there is a tendency in olive production systems to reduce tillage or keep a vegetative cover to reduce soil erosion and degradation. However, there is scarce information on the effects of different soil management systems (SMS) in soil bacterial community composition of olive groves. In this study, we have evaluated the effects of soil type and different SMS implemented to control weeds in the structure and diversity of bacterial communities of 58 soils in the two geographic areas that best represent the organic olive production systems in Spain. Bacterial community composition assessed by frequency and intensity of occurrence of terminal restriction profiles (TRFs) derived from terminal restriction fragment length polymorphism (T-RFLP) analysis of amplified 16S ribosomal deoxyribonucleic acid were strongly correlated with soil type/field site (Eutric/Calcaric) that differed mainly in soil particle size distribution and soil pH, followed by a strong effect of SMS, in that order. Canonical discriminant (CD) analysis of TRFs properly classified all of the olive orchard soils as belonging to their respective soil type or SMS. Furthermore, only a small set of TRFs were enough to clearly and significantly differentiate soil samples according to soil type or SMS. Those specific TRFs could be used as bioindicators to assess the effect of changes in SMS aimed to enhance soil quality in olive production systems. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  9. [Effect of Long-Term Fertilization on Organic Nitrogen Functional Groups in Black Soil as Revealed by Synchrotron-Based X-Ray Absorption Near-Edge Structure Spectroscopy].

    Science.gov (United States)

    Li, Hui; Gao, Qiang; Wang, Shuai; Zhu, Ping; Zhang, Jin-jing; Zhao, Yi-dong

    2015-07-01

    Nitrogen (N) is a common limiting nutrient in crop production. The N content of soil has been used as an important soil fertility index. Organic N is the major form of N in soil. In most agricultural surface soils, more than 90% of total N occurs in organic forms. Therefore, understanding the compositional characteristics of soil organic N functional groups can provide the scientific basis for formulating the reasonable farmland management strategies. Synchrotron radiation soft X-ray absorption near-edge structure (N K-edge XANES) spectroscopy is the most powerful tool to characterize in situ organic N functional groups compositions in soil. However, to our most knowledge, no studies have been conducted to examine the organic N functional groups compositions of soil using N K-edge XANES spectroscopy under long-term fertilization practices. Based on a long-term field experiment (started in 1990) in a black soil (Gongzhuling, Northeast China), we investigated the differences in organic N functional groups compositions in bulk soil and clay-size soil fraction among fertilization patterns using synchrotron-based N K- edge XANES spectroscopy. Composite soil samples (0-20 cm) were collected in 2008. The present study included six treatments: farmland fallow (FALL), no-fertilization control (CK), chemical nitrogen, phosphorus, and potassium fertilization (NPK), NPK in combination with organic manure (NPKM), 1.5 times of NPKM (1.5 NPKM), and NPK in combination with maize straw (NPKS). The results showed that N K-edge XANES spectra of all the treatments under study exhibited characteristic absorption peaks in the ranges of 401.2-401.6 and 402.7-403.1 eV, which were assigned as amides/amine-N and pyrrole-N, respectively. These characteristic absorption peaks were more obvious in clay-size soil fraction than in bulk soil. The results obtained from the semi-quantitative analysis of N K-edge XANES spectra indicated that the relative proportion of amides/amine-N was the highest

  10. Organic radionuclide compounds in soil solutions and their role in elements absorption in plants

    International Nuclear Information System (INIS)

    Agapkin, G.I.; Tikhomirov, F.A.

    1991-01-01

    The results of reference experiments with introduction of radioactive labels ( 35 S, 45 Ca, 59 Fe, 85 , 125 I) into 5 types of climatophytic soils by the method of radiogel-chromatography allow to ascertain that in soil solutions 59 Fe and 125 I incorporate completely and 35 S, 45 Ca and 85 Sr incorporate by 60-90 % into the composition of one of three fractions of organic compounds with molecular masses of 4x10 2 -6x10 4 . It is shown that significant variations between soils in the absorption of such radionuclides as 4 5 Ca, 58 Fe, 85 Sr and 125 I are celated to a different degree of their transport into soil solutions as well as to differencies in their distribution by molecular-mass fractions of water-soluble organic compounds

  11. Experimental Study of Soil Organic Matter Loss From Cultivated Field Plots In The Venezuelan Andes.

    Science.gov (United States)

    Bellanger, B.; Huon, S.; Velasquez, F.; Vallès, V.; Girardin A, C.; Mariotti, A. B.

    The question of discriminating sources of organic matter in suspended particles of stream flows can be addressed by using total organic carbon (TOC) concentration and stable isotope (13C, 15N) measurements when constant fluxes of organic matter supply can be assumed. However, little is known on the dynamics of organic matter release during soil erosion and on the temporal stability of its isotopic signature. In this study, we have monitored soil organic carbon loss and water runoff using natural rainfall events on three experimental field plots with different vegetation cover (bare soil, maize and coffee fields), set up on natural slopes of a tropical mountainous watershed in NW Venezuela (09°13'32'' ­ 09°10'00''N, 70°13'49'' ­ 70°18'34''W). Runoff and soil loss are markedly superior for the bare field plot than for the coffee field plot: by a factor 15 ­ 36, respectively, for the five-month experiment, and by a factor 30 ­ 120, respectively, during a single rainfall event experiment. Since runoff and soil organic matter loss are closely linked during most of the flow (at the time scales of this study), TOC concentration in suspended matter is constant. Furthermore, stable isotope compositions reflect those of top-soil organic matter from which they originate.

  12. Let's Break it Down: A Study of Organic Decomposition Rates in Clay Soil

    Science.gov (United States)

    Weiss, E.

    2016-12-01

    In this experiment I will be testing if temperature affects the organic decomposition rates in clay soil. I will need to be able to clean and weigh each filter paper without disrupting my data damaging or brushing off additional paper material. From there I need to be able to analyze and interpret my data to factor anything else that may affect the decomposition rates in the soil. Soil decomposers include bacteria and fungi. They obtain energy from plant and animal detritus through aerobic decomposition, which is similar to how humans break down sugar. The formula is: C6H12O6 + O2 → CO2 + H2O + energy. Besides oxygen and sugar the organisms need nutrients such as water and sustainable temperatures. Decomposition is important to us because it helps regulate soil structure, moisture, temperature, and provides nutrients to soil organisms. This matters on a global scale since decomposers release a large amount of carbon when breaking down matter, which contributes to greenhouse gasses such as carbon dioxide and methane. These greenhouse gasses affect the earth's climate. People who care about decomposition are farmers and those in agriculture, as well as environmental scientists. Even national parks might care because decomposition may affect park safety, how the park looks, and the amount of plants and wildlife. Things that can affect decomposition are the decomposers in the soil, temperature, and water or moisture. My secondary research also showed that PH and chemical composition of the soil affect the rate of decomposition.Cold or freezing temperatures can help preserve organic material in soil because it freezes the soil and moisture, making it too dense for the organic decomposers to break down the organic matter. Soil also can be preserved by drying out and being stored at 4º Celsius (or 39º Fahrenheit) for 28 days. However, soil can degrade slowly in these conditions because it is not frozen and can be oxidized.

  13. Soil greenhouse gas emissions from afforested organic soil croplands and cutaway peatlands

    International Nuclear Information System (INIS)

    Maekiranta, P.; Hytoenen, J.; Aro, L.

    2007-01-01

    The effects of land-use and land-use change on soil greenhouse gas (GHG) fluxes are of concern due to Kyoto Protocol requirements. To quantify the soil GHG-fluxes of afforested organic soils in Finland, chamber measurements of soil CO 2 , CH 4 and N 2 O fluxes were made during the years 2002 to 2005 on twelve organic soil cropland and six cutaway peatland sites afforested 9 to 35 years ago. The annual soil CO 2 effluxes were statistically modelled using soil temperature as the driving variable and the annual CH 4 and N 2 O fluxes were estimated using the average fluxes during the measurement period. Soil CO 2 effluxes on afforested organic soil croplands varied from 207 to 539 g CO 2 -C m -2 a -1 and on cutaway peatlands from 276 to 479 g CO 2 -C m -2 a -1 . Both the afforested organic soil cropland and cutaway peatland sites acted mainly as small sinks for CH 4 ; the annual flux ranged from -0.32 to 0.61 g CH 4 -C m -2 . Afforested organic croplands emitted more N 2 O (from 0.1 to over 3.0 g N 2 O-N m -2 a -1 ) than cutaway peatland sites (from 0.01 to 0.48 g N 2 O-N m -2 a -1 ). Due to the decrease in soil CO 2 efflux, and no change in CH 4 and N 2 O fluxes, afforestation of organic croplands appears to decrease the greenhouse impact of these lands. (orig.)

  14. Characterization of Soil Organic Matter in Peat Soil with Different Humification Levels using FTIR

    Science.gov (United States)

    Teong, I. T.; Felix, N. L. L.; Mohd, S.; Sulaeman, A.

    2016-07-01

    Peat soil is defined as an accumulation of the debris and vegetative under the water logging condition. Soil organic matter of peat soil was affected by the environmental, weather, types of vegetative. Peat soil was normally classified based on its level of humification. Humification can be defined as the transformation of numerous group of substances (proteins, carbohydrates, lipids, etc.) and individual molecules present in living organic matter into group of substances with similar properties (humic substances). During the peat transformation process, content of soil organic matter also will change. Hence, that is important to determine out the types of the organic compound. FTIR (Fourier Transform Infrared) is a machine which is used to differential soil organic matter by using infrared. Infrared is a types of low energy which can determine the organic minerals. Hence, FTIR can be suitable as an indicator on its level of humification. The main objective of this study is to identify an optimized method to characterization of the soil organic content in different level of humification. The case study areas which had been chosen for this study are Parit Sulong, Batu Pahat and UCTS, Sibu. Peat soil samples were taken by every 0.5 m depth until it reached the clay layer. However, the soil organic matter in different humification levels is not significant. FTIR is an indicator which is used to determine the types of soil, but it is unable to differentiate the soil organic matter in peat soil FTIR can determine different types of the soil based on different wave length. Generally, soil organic matter was found that it is not significant to the level of humification.

  15. Heat impact caused molecular level changes in solid and dissolved soil organic matter

    Science.gov (United States)

    Hofmann, Diana; Steffen, Bernhard; Eckhardt, Kai-Uwe; Leinweber, Peter

    2015-04-01

    The ubiquitous abundance of pyrolysed, highly aromatic organic matter, called "Black Carbon" (BC), in all environmental compartments became increasingly important in different fields of research beyond intensive investigated atmospheric aerosol due to climatic relevance. Its predominant high resistance to abiotic and biotic degradation resulted in turnover times from less than a century to several millennia. This recalcitrance led to the enrichment of BC in soils, accounting for 1-6% (European forest soils) to 60% (Chernozems) of total soil organic matter (SOM). Hence, soil BC acts an important sink in the global carbon cycle. In contrast, consequences for the nitrogen cycle up to date are rather inconsistently discussed. Soil related dissolved organic matter (DOM) is a major controlling factor in soil formation, an important pathway of organic matter transport and one of the largest active carbon reservoirs on earth, if considering oceans and other bodies of water. The aim of this study was to evaluate the effects of artificially simulated wildfire by thermal treatment on the molecular composition of water extractable soil organic matter (DOM). Soils from two outdoor lysimeters with different management history were investigated. Soil samples, non-heated and heated up to 350°C were analyzed for elemental composition (carbon, nitrogen and sulfur) and for bulk molecular composition by Pyrolysis-Field Ionization Mass Spectrometry (Py-FIMS) and synchrotron-based X-ray Absorption Near-Edge Spectroscopy (XANES) at the C- and N K-edges. DOM-samples obtained by hot water extraction, desalting and concentration by solid phase extraction were subsequently analyzed by flow injection analysis in a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FTICR-MS), equipped with an ESI source and a 7 T supra-conducting magnet (LTQ-FT Ultra, ThermoFisher Scientific). This technique is the key technique for the analysis of complex samples due to its outstanding mass

  16. [Response of mineralization of dissolved organic carbon to soil moisture in paddy and upland soils in hilly red soil region].

    Science.gov (United States)

    Chen, Xiang-Bi; Wang, Ai-Hua; Hu, Le-Ning; Huang, Yuan; Li, Yang; He, Xun-Yang; Su, Yi-Rong

    2014-03-01

    Typical paddy and upland soils were collected from a hilly subtropical red-soil region. 14C-labeled dissolved organic carbon (14C-DOC) was extracted from the paddy and upland soils incorporated with 14C-labeled straw after a 30-day (d) incubation period under simulated field conditions. A 100-d incubation experiment (25 degrees C) with the addition of 14C-DOC to paddy and upland soils was conducted to monitor the dynamics of 14C-DOC mineralization under different soil moisture conditions [45%, 60%, 75%, 90%, and 105% of the field water holding capacity (WHC)]. The results showed that after 100 days, 28.7%-61.4% of the labeled DOC in the two types of soils was mineralized to CO2. The mineralization rates of DOC in the paddy soils were significantly higher than in the upland soils under all soil moisture conditions, owing to the less complex composition of DOC in the paddy soils. The aerobic condition was beneficial for DOC mineralization in both soils, and the anaerobic condition was beneficial for DOC accumulation. The biodegradability and the proportion of the labile fraction of the added DOC increased with the increase of soil moisture (45% -90% WHC). Within 100 days, the labile DOC fraction accounted for 80.5%-91.1% (paddy soil) and 66.3%-72.4% (upland soil) of the cumulative mineralization of DOC, implying that the biodegradation rate of DOC was controlled by the percentage of labile DOC fraction.

  17. Stimulation of soil microorganisms in pesticide-contaminated soil using organic materials

    Directory of Open Access Journals (Sweden)

    Ima Yudha Perwira

    2016-08-01

    Full Text Available Agrochemicals such as pesticides have contributed to significant increases in crop yields; however, they can also be linked to adverse effects on human health and soil microorganisms. For efficient bioremediation of pesticides accumulated in agricultural fields, stimulation of microorganisms is necessary. In this study, we investigated the relationships between bacterial biomass and total carbon (TC and total nitrogen (TN in 427 agricultural soils. The soil bacterial biomass was generally positively correlated with TC and TN contents in the soil, but some soils had a low bacterial biomass despite containing high amounts of TC and TN. Soils of two fields (fields A and B with low bacterial biomass but high TC and TN contents were investigated. Long-term pesticide use (dichloropropane-dichloropropene and fosthiazate in field A and chloropicrin in field B appeared to have contributed to the low bacterial biomass observed in these soils. Soil from field A was treated with different organic materials and incubated for 1 month under laboratory conditions. The bacterial biomass in field A soil was enhanced in treatments containing organic materials rich in TN. Application of organic materials stimulated the growth of microorganisms with the potential to bioremediate pesticide-polluted soils.

  18. Increased precipitation accelerates soil organic matter turnover associated with microbial community composition in topsoil of alpine grassland on the eastern Tibetan Plateau.

    Science.gov (United States)

    Han, Conghai; Wang, Zongli; Si, Guicai; Lei, Tianzhu; Yuan, Yanli; Zhang, Gengxin

    2017-10-01

    Large quantities of carbon are stored in alpine grassland of the Tibetan Plateau, which is extremely sensitive to climate change. However, it remains unclear whether soil organic matter (SOM) in different layers responds to climate change analogously, and whether microbial communities play vital roles in SOM turnover of topsoil. In this study we measured and collected SOM turnover by the 14 C method in alpine grassland to test climatic effects on SOM turnover in soil profiles. Edaphic properties and microbial communities in the northwestern Qinghai Lake were investigated to explore microbial influence on SOM turnover. SOM turnover in surface soil (0-10 cm) was more sensitive to precipitation than that in subsurface layers (10-40 cm). Precipitation also imposed stronger effects on the composition of microbial communities in the surface layer than that in deeper soil. At the 5-10 cm depth, the SOM turnover rate was positively associated with the bacteria/fungi biomass ratio and the relative abundance of Acidobacteria, both of which are related to precipitation. Partial correlation analysis suggested that increased precipitation could accelerate the SOM turnover rate in topsoil by structuring soil microbial communities. Conversely, carbon stored in deep soil would be barely affected by climate change. Our results provide valuable insights into the dynamics and storage of SOM in alpine grasslands under future climate scenarios.

  19. Role of soil micro-organisms in the sorption of radionuclides in organic systems

    International Nuclear Information System (INIS)

    Parekh, N.R.; Potter, E.D.; Poskitt, J.M.; Dodd, B.A.; Sanchez, A.

    2004-01-01

    Although the fraction of radionuclides linked to soil organic matter and soil microorganisms may be relatively small when compared to the amount bound to the mineral constituents, (mostly irreversibly bound), this fraction is of great importance as it remains readily exchangeable and is thus available for plant uptake. Many studies have measured the uptake of radionuclides by organic soils but the role of soil micro-organisms may have been masked by the presence of even small amounts of clay minerals occurring in these soils. We have carried out a series of experiments using a biologically active, 'mineral-free' organic soil produced under laboratory conditions, to determine the potential of soil micro-organisms to accumulate radionuclides Cs-134 and Sr-85. Biological uptake and release was differentiated from abiotic processes by comparing experimental results with inoculated and non-inoculated sterile organic material. We have investigated the role of different clay minerals, competing potassium and calcium ions, and changes in temperature on the sorption of Cs and Sr isotopes. The results from studies so far show conclusively that living components of soil systems are of primary importance in the uptake of radionuclides in organic material, microorganisms also influence the importance of chemical factors (e.g. adsorption to clay minerals) which may play a secondary role in these highly organic systems. In further experiments we hope to define the precise role of specific soil micro-organisms in these organic systems. (author)

  20. Acidity controls on dissolved organic carbon mobility in organic soils

    Czech Academy of Sciences Publication Activity Database

    Evans, Ch. D.; Jones, T.; Burden, A.; Ostle, N.; Zielinski, P.; Cooper, M.; Peacock, M.; Clark, J.; Oulehle, Filip; Cooper, D.; Freeman, Ch.

    2012-01-01

    Roč. 18, č. 11 (2012), s. 3317-3331 ISSN 1354-1013 Institutional support: RVO:67179843 Keywords : acidity * dissolved organic carbon * organic soil * peat * podzol * soil carbon * sulphur Subject RIV: EH - Ecology, Behaviour Impact factor: 6.910, year: 2012

  1. Soil Organic Matter Accumulation and Carbon Fractions along a Moisture Gradient of Forest Soils

    Directory of Open Access Journals (Sweden)

    Ewa Błońska

    2017-11-01

    Full Text Available The aim of the study was to present effects of soil properties, especially moisture, on the quantity and quality of soil organic matter. The investigation was performed in the Czarna Rózga Reserve in Central Poland. Forty circular test areas were located in a regular grid of points (100 × 300 m. Each plot was represented by one soil profile located at the plot’s center. Sample plots were located in the area with Gleysols, Cambisols and Podzols with the water table from 0 to 100 cm. In each soil sample, particle size, total carbon and nitrogen content, acidity, base cations content and fractions of soil organic matter were determined. The organic carbon stock (SOCs was calculated based on its total content at particular genetic soil horizons. A Carbon Distribution Index (CDI was calculated from the ratio of the carbon accumulation in organic horizons and the amount of organic carbon accumulation in the mineral horizons, up to 60 cm. In the soils under study, in the temperate zone, moisture is an important factor in the accumulation of organic carbon in the soil. The highest accumulation of carbon was observed in soils of swampy variant, while the lowest was in the soils of moist variant. Large accumulation of C in the soils with water table 80–100 cm results from the thick organic horizons that are characterized by lower organic matter decomposition and higher acidity. The proportion of carbon accumulation in the organic horizons to the total accumulation in the mineral horizons expresses the distribution of carbon accumulated in the soil profile, and is a measure of quality of the organic matter accumulated. Studies have confirmed the importance of moisture content in the formation of the fractional organic matter. With greater soil moisture, the ratio of humic to fulvic acids (HA/FA decreases, which may suggest an increase in carbon mobility in soils.

  2. Uncovering trophic positions and food resources of soil animals using bulk natural stable isotope composition.

    Science.gov (United States)

    Potapov, Anton M; Tiunov, Alexei V; Scheu, Stefan

    2018-06-19

    Despite the major importance of soil biota in nutrient and energy fluxes, interactions in soil food webs are poorly understood. Here we provide an overview of recent advances in uncovering the trophic structure of soil food webs using natural variations in stable isotope ratios. We discuss approaches of application, normalization and interpretation of stable isotope ratios along with methodological pitfalls. Analysis of published data from temperate forest ecosystems is used to outline emerging concepts and perspectives in soil food web research. In contrast to aboveground and aquatic food webs, trophic fractionation at the basal level of detrital food webs is large for carbon and small for nitrogen stable isotopes. Virtually all soil animals are enriched in 13 C as compared to plant litter. This 'detrital shift' likely reflects preferential uptake of 13 C-enriched microbial biomass and underlines the importance of microorganisms, in contrast to dead plant material, as a major food resource for the soil animal community. Soil organic matter is enriched in 15 N and 13 C relative to leaf litter. Decomposers inhabiting mineral soil layers therefore might be enriched in 15 N resulting in overlap in isotope ratios between soil-dwelling detritivores and litter-dwelling predators. By contrast, 13 C content varies little between detritivores in upper litter and in mineral soil, suggesting that they rely on similar basal resources, i.e. little decomposed organic matter. Comparing vertical isotope gradients in animals and in basal resources can be a valuable tool to assess trophic interactions and dynamics of organic matter in soil. As indicated by stable isotope composition, direct feeding on living plant material as well as on mycorrhizal fungi is likely rare among soil invertebrates. Plant carbon is taken up predominantly by saprotrophic microorganisms and channelled to higher trophic levels of the soil food web. However, feeding on photoautotrophic microorganisms and non

  3. Organic matter dynamics and N mineralization in grassland soils

    OpenAIRE

    Hassink, J.

    1995-01-01


    The aims of this study are i) to improve our understanding of the interactions between soil texturelsoil structure, soil organic matter, soil biota and mineralization in grassland soils, ii) to develop a procedure that yields soil organic matter fractions that can be determined directly and can be used in soil organic matter models, iii) to develop a model that predicts the long-term dynamics of soil organic matter, iv) to develop a simple model that can be used by farmers and advi...

  4. Decontaminating soil organic pollutants with manufactured nanoparticles.

    Science.gov (United States)

    Li, Qi; Chen, Xijuan; Zhuang, Jie; Chen, Xin

    2016-06-01

    Organic pollutants in soils might threaten the environmental and human health. Manufactured nanoparticles are capable to reduce this risk efficiently due to their relatively large capacity of sorption and degradation of organic pollutants. Stability, mobility, and reactivity of nanoparticles are prerequisites for their efficacy in soil remediation. On the basis of a brief introduction of these issues, this review provides a comprehensive summary of the application and effectiveness of various types of manufactured nanoparticles for removing organic pollutants from soil. The main categories of nanoparticles include iron (oxides), titanium dioxide, carbonaceous, palladium, and amphiphilic polymeric nanoparticles. Their advantages (e.g., unique properties and high sorption capacity) and disadvantages (e.g., high cost and low recovery) for soil remediation are discussed with respect to the characteristics of organic pollutants. The factors that influence the decontamination effects, such as properties, surfactants, solution chemistry, and soil organic matter, are addressed.

  5. Long-term effects of rainforest disturbance on the nutrient composition of throughfall, organic layer percolate and soil solution at Mt. Kilimanjaro.

    Science.gov (United States)

    Schrumpf, Marion; Axmacher, Jan C; Zech, Wolfgang; Lehmann, Johannes; Lyaruu, Herbert V C

    2007-04-15

    At the lower parts of the forest belt at Mt. Kilimanjaro, selective logging has led to a mosaic of mature forest, old secondary forests ( approximately 60 years), and old clearings ( approximately 10 years) covered by shrub vegetation. These variations in the vegetation are reflected by differences in nutrient leaching from the canopy and in both amount and quality of litter reaching the ground, thereby also influencing mineralization rates and the composition of seepage water in litter percolate and soil solution. The aim of this study was to investigate how above- and belowground nutrient dynamics vary between regeneration stages, and if forest regeneration at the clearings is hampered by a deterioration of abiotic site conditions. K, Mg, Ca, Na and N compounds were analysed in rainfall, throughfall, organic layer percolate and the soil solution to a depth of 1.00 m at three clearings, three secondary forest and four mature forest sites. Element fluxes via throughfall showed only small variations among regeneration stages except for K and NO(3)-N. With 57-83 kg ha(-1) a(-1)and 2.6-4.1 kg ha(-1) a(-1) respectively, K and NO(3)-N fluxes via throughfall were significantly higher at the clearings than at the mature forest sites (32-37 and 0.7-1.0 kg ha(-1) a(-1) for K and NO(3)-N). In organic layer percolate and in soil solution at 0.15-m soil depth, concentrations of K, Mg, Ca and N were highest at the clearings. In the organic layer percolate, median K concentrations were e.g. 7.4 mg l(-1) for the clearings but only 1.4 mg l(-1) for the mature forests, and for NO(3)-N, median concentrations were 3.1 mg l(-1) for the clearings but only 0.92 mg l(-1) for the mature forest sites. Still, differences in annual means between clearings and mature forests were not always significant due to a high variability within the clearings. With the exception of NO(3)-N, belowground nutrient concentrations in secondary forests ranged between concentrations in mature forests and

  6. Management of soil-borne diseases of organic vegetables

    Directory of Open Access Journals (Sweden)

    Shafique Hafiza Asma

    2016-07-01

    Full Text Available With the rising awareness of the adverse effects of chemical pesticides, people are looking for organically grown vegetables. Consumers are increasingly choosing organic foods due to the perception that they are healthier than those conventionally grown. Vegetable crops are vulnerable to a range of pathogenic organisms that reduce yield by killing the plant or damaging the product, thus making it unmarketable. Soil-borne diseases are among the major factors contributing to low yields of organic produce. Apart from chemical pesticides there are several methods that can be used to protect crops from soil-borne pathogens. These include the introduction of biocontrol agents against soil-borne plant pathogens, plants with therapeutic effects and organic soil amendments that stimulate antagonistic activities of microorganisms to soil-borne diseases. The decomposition of organic matter in soil also results in the accumulation of specific compounds that may be antifungal or nematicidal. With the growing interest in organic vegetables, it is necessary to find non chemical means of plant disease control. This review describes the impact of soil-borne diseases on organic vegetables and methods used for their control.

  7. Soil moisture effects on the carbon isotopic composition of soil respiration

    Science.gov (United States)

    The carbon isotopic composition ( 13C) of recently assimilated plant carbon is known to depend on water-stress, caused either by low soil moisture or by low atmospheric humidity. Air humidity has also been shown to correlate with the 13C of soil respiration, which suggests indir...

  8. Molecular composition of recycled organic wastes, as determined by solid-state 13C NMR and elemental analyses

    International Nuclear Information System (INIS)

    Eldridge, S.M.; Chen, C.R.; Xu, Z.H.; Nelson, P.N.; Boyd, S.E.; Meszaros, I.; Chan, K.Y.

    2013-01-01

    Highlights: • Model estimated the molecular C components well for most RO wastes. • Molecular nature of organic matter in RO wastes varied widely. • Molecular composition by NMR modelling preferable to extraction techniques. • Some model shortcomings in estimating molecular composition of biochars. • Waste molecular composition important for carbon/nutrient outcomes in soil. - Abstract: Using solid state 13 C NMR data and elemental composition in a molecular mixing model, we estimated the molecular components of the organic matter in 16 recycled organic (RO) wastes representative of the major materials generated in the Sydney basin area. Close correspondence was found between the measured NMR signal intensities and those predicted by the model for all RO wastes except for poultry manure char. Molecular nature of the organic matter differed widely between the RO wastes. As a proportion of organic C, carbohydrate C ranged from 0.07 to 0.63, protein C from <0.01 to 0.66, lignin C from <0.01 to 0.31, aliphatic C from 0.09 to 0.73, carbonyl C from 0.02 to 0.23, and char C from 0 to 0.45. This method is considered preferable to techniques involving imprecise extraction methods for RO wastes. Molecular composition data has great potential as a predictor of RO waste soil carbon and nutrient outcomes

  9. Seasonal Variation in Soil Microbial Biomass, Bacterial Community Composition and Extracellular Enzyme Activity in Relation to Soil Respiration in a Northern Great Plains Grassland

    Science.gov (United States)

    Wilton, E.; Flanagan, L. B.

    2014-12-01

    Soil respiration rate is affected by seasonal changes in temperature and moisture, but is this a direct effect on soil metabolism or an indirect effect caused by changes in microbial biomass, bacterial community composition and substrate availability? In order to address this question, we compared continuous measurements of soil and plant CO2 exchange made with an automatic chamber system to analyses conducted on replicate soil samples collected on four dates during June-August. Microbial biomass was estimated from substrate-induced respiration rate, bacterial community composition was determined by 16S rRNA amplicon pyrosequencing, and β-1,4-N-acetylglucosaminidase (NAGase) and phenol oxidase enzyme activities were assayed fluorometrically or by absorbance measurements, respectively. Soil microbial biomass declined from June to August in strong correlation with a progressive decline in soil moisture during this time period. Soil bacterial species richness and alpha diversity showed no significant seasonal change. However, bacterial community composition showed a progressive shift over time as measured by Bray-Curtis dissimilarity. In particular, the change in community composition was associated with increasing relative abundance in the alpha and delta classes, and declining abundance of the beta and gamma classes of the Proteobacteria phylum during June-August. NAGase showed a progressive seasonal decline in potential activity that was correlated with microbial biomass and seasonal changes in soil moisture. In contrast, phenol oxidase showed highest potential activity in mid-July near the time of peak soil respiration and ecosystem photosynthesis, which may represent a time of high input of carbon exudates into the soil from plant roots. This input of exudates may stimulate the activity of phenol oxidase, a lignolytic enzyme involved in the breakdown of soil organic matter. These analyses indicated that seasonal change in soil respiration is a complex

  10. Changes of soil organic matter and microbial activity in irrigated and non irrigated olive groves

    Science.gov (United States)

    Kavvadias, Victor; Papadopoulou, Maria; Theocharopoulos, Sideris; Vavoulidou, Evagelia; Doula, Maria; Reppas, Spiros

    2014-05-01

    The implementation of olive cultivation techniques in Greece has not been systematically tested under the prevailing Mediterranean conditions. A LIFE+ project was initiated (oLIVE-CLIMA; LIFE 11/ENV/000942) aiming to introduce new management practices in olive tree crops that lead to increased carbon dioxide uptake by plants as well as carbon sequestration from the atmosphere and reverse the trend of soil organic matter decline, erosion and desertification. This paper presents data on soil organic matter and microbial activity from a soil campaign in a pilot region in Greece, and particularly in the area of Chora, prefecture of Messinia, South west Peloponnese. The soil campaign took place during the period December 2012-February 2013. Twelve soil parcels of olive groves were selected (6 irrigated and 6 rainfed) and in each soil parcel six composite soil samples were taken from 0-10 cm depth at equal intervals along a straight line of the trunk of the tree to the middle of the distance from the nearest tree of the next tree series. The first three samples were under olive tree canopy. An additional composite sample was taken at depth of 10-40 cm. Soil samples were analyzed for soil physicochemical and biological properties. In this study results for total organic carbon (TOC), soil basal microbial respiration (BR), microbial biomass C (MB-C) from the region of Messinia, are presented. Organic matter was determined by dichromate oxidation. The microbial activity was measured by the amount of CO2 evolution, while microbial biomass C was determined by substrate-induced respiration, after the addition of glucose. The results showed considerable differences in TOC, BR and MB-C associated with the sampling position and soil depth. The higher TOC, BR and MB-C values, in most cases, were determined in samples taken from points under the canopy, but not close to the tree trunk compared to the sampling points outside the canopy. This indicates the positive effect of

  11. Effects of thermal desorption on the composition of two coking plant soils: Impact on solvent extractable organic compounds and metal bioavailability

    Energy Technology Data Exchange (ETDEWEB)

    Biache, Coralie [G2R UMR 7566, Nancy Universite, CNRS, Boulevard des Aiguillettes B.P. 239, F-54506 Vandoeuvre-les-Nancy (France); LIMOS UMR 7137, Nancy Universite, CNRS, Boulevard des Aiguillettes B.P. 239, F-54506 Vandoeuvre-les-Nancy (France)], E-mail: coralie.biache@g2r.uhp-nancy.fr; Mansuy-Huault, Laurence; Faure, Pierre [G2R UMR 7566, Nancy Universite, CNRS, Boulevard des Aiguillettes B.P. 239, F-54506 Vandoeuvre-les-Nancy (France); Munier-Lamy, Colette; Leyval, Corinne [LIMOS UMR 7137, Nancy Universite, CNRS, Boulevard des Aiguillettes B.P. 239, F-54506 Vandoeuvre-les-Nancy (France)

    2008-12-15

    To evaluate the efficiency and the influence of thermal desorption on the soil organic compartment, contaminated soils from coking plant sites (NM and H) were compared to their counterparts treated with thermodesorption. The extractable organic matter, and the metal content and distribution with soil compartments were studied. In both thermodesorbed soils, PAH (polycyclic aromatic hydrocarbon) degradation exceeded 90%. However, the thermal desorption led not only to a volatilization of the organic compounds but also to the condensation of extractable organic matter. The treatments only affected the Fe and Zn distribution within the more stable fractions, whereas the organic compound degradation did not affect their mobility and availability. - Thermal desorption does not induce a metal mobilization but condensation seems to occur during the treatment.

  12. Predicting soil particle density from clay and soil organic matter contents

    DEFF Research Database (Denmark)

    Schjønning, Per; McBride, R.A.; Keller, T.

    2017-01-01

    Soil particle density (Dp) is an important soil property for calculating soil porosity expressions. However, many studies assume a constant value, typically 2.65Mgm−3 for arable, mineral soils. Fewmodels exist for the prediction of Dp from soil organic matter (SOM) content. We hypothesized...

  13. Soil microorganisms determine the sorption of radionuclides within organic soil systems

    International Nuclear Information System (INIS)

    Parekh, N.R.; Poskitt, J.M.; Dodd, B.A.; Potter, E.D.; Sanchez, A.

    2008-01-01

    The potential of soil microorganisms to enhance the retention of 137 Cs and 85 Sr in organic systems was assessed in a series of experiments. A biologically active, 'mineral-free', organic material, produced under laboratory conditions from leaves, was used as the uptake matrix in all experiments to minimise potential interference from competing clay minerals. Biological uptake and release were differentiated from abiotic processes by comparing the sorption of radionuclides in sterilised organic material with sterile material inoculated with soil extracts or single fungal strains. Our results show conclusively that living components of soil systems are of primary importance in the uptake of radionuclides in organic material. The presence of soil microorganisms significantly enhanced the retention of Cs in organic systems and ∼70% of the Cs spike was strongly (irreversibly) bound (remained non-extractable) in the presence of microorganisms compared to only ∼10% in abiotic systems. Sorption of 85 Sr was not significantly influenced by the presence of soil microorganisms. A non-linear temperature response was observed for the retention in biotic systems with increased uptake at between 10 and 30 deg. C and lower retention at temperatures above or below the optimum range. The optimum temperatures for biological uptake were between 15 and 20 deg. C for Cs, and 25 and 30 deg. C for Sr. Our results indicate that single strains of soil and saprotrophic fungi make an important contribution to the sorption of Cs and Sr in organic systems, but can only account for part of the strong, irreversible binding observed in biotic systems. Single strains of soil fungi increased the amount of non-extractable 137 Cs (by ∼30%) and 85 Sr (by ∼20%) in the organic systems as compared to abiotic systems, but the major fraction of 137 Cs and 85 Sr sorbed in systems inoculated with saprotrophic fungi remained extractable

  14. Metal oxides, clay minerals and charcoal determine the composition of microbial communities in matured artificial soils and their response to phenanthrene.

    Science.gov (United States)

    Babin, Doreen; Ding, Guo-Chun; Pronk, Geertje Johanna; Heister, Katja; Kögel-Knabner, Ingrid; Smalla, Kornelia

    2013-10-01

    Microbial communities in soil reside in a highly heterogeneous habitat where diverse mineral surfaces, complex organic matter and microorganisms interact with each other. This study aimed to elucidate the long-term effect of the soil mineral composition and charcoal on the microbial community composition established in matured artificial soils and their response to phenanthrene. One year after adding sterile manure to different artificial soils and inoculating microorganisms from a Cambisol, the matured soils were spiked with phenanthrene or not and incubated for another 70 days. 16S rRNA gene and internal transcribed spacer fragments amplified from total community DNA were analyzed by denaturing gradient gel electrophoresis. Metal oxides and clay minerals and to a lesser extent charcoal influenced the microbial community composition. Changes in the bacterial community composition in response to phenanthrene differed depending on the mineral composition and presence of charcoal, while no shifts in the fungal community composition were observed. The abundance of ring-hydroxylating dioxygenase genes was increased in phenanthrene-spiked soils except for charcoal-containing soils. Here we show that the formation of biogeochemical interfaces in soil is an ongoing process and that different properties present in artificial soils influenced the bacterial response to the phenanthrene spike. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  15. Soil organic matter dynamics in Mediterranean A-horizons-The use of analytical pyrolysis to ascertain land-use history

    NARCIS (Netherlands)

    Schellekens, J.; Barbera, G.G.; Buurman, P.; Perez-Jorda, G.; Martinez-Cortizas, A.

    2013-01-01

    In archaeology and nature conservation studies, knowledge about (pre)historical land-use is important. The molecular composition of soil organic matter (SOM) supplies information about its history, as its composition is controlled by input material and decay processes. In this study, the molecular

  16. Preservation of labile organic matter in soils of drained thaw lakes in Northern Alaska

    Science.gov (United States)

    Mueller, Carsten W.; Rethemeyer, Janet; Kao-Kniffin, Jenny; Löppmann, Sebastian; Hinkel, Kenneth; Bockheim, James

    2014-05-01

    A large number of studies predict changing organic matter (OM) dynamics in arctic soils due to global warming. In contrast to rather slowly altering bulk soil properties, single soil organic matter (SOM) fractions can provide a more detailed picture of the dynamics of differently preserved SOM pools in climate sensitive arctic regions. By the study of the chemical composition of such distinctive SOM fractions using nuclear magnetic resonance spectroscopy (NMR) together with radiocarbon analyses it is possible to evaluate the stability of the major OM pools. Approximately 50-75% of Alaska's Arctic Coastal Plain is covered with thaw lakes and drained thaw lakes that follow a 5,000 yr cycle of development (between creation and final drainage), thus forming a natural soil chronosequence. The drained thaw lakes offer the possibility to study SOM dynamics affected by permafrost processes over millennial timescales. In April 2010 we sampled 16 soil cores (including the active and permanent layer) reaching from young drained lakes (0-50 years since drainage) to ancient drained lakes (3000-5500 years since drainage). Air dried soil samples from soil horizons of the active and permanent layer were subjected to density fractionation in order to differentiate particulate OM and mineral associated OM. The chemical composition of the SOM fractions was analyzed by 13C CPMAS NMR spectroscopy. For a soil core of a young and an ancient drained thaw lake basin we also analyzed the 14C content. For the studied soils we can show that up to over 25 kg OC per square meter are stored mostly as labile, easily degradable organic matter rich in carbohydrates. In contrast only 10 kg OC per square meter were sequestered as presumably more stable mineral associated OC dominated by aliphatic compounds. Comparable to soils of temperate regions, we found small POM (dating we could show the stabilization of younger more labile OM at greater depth in buried O horizons. Additionally the study of the

  17. Soil Microbial Activity in Conventional and Organic Agricultural Systems

    Directory of Open Access Journals (Sweden)

    Romero F.V. Carneiro

    2009-06-01

    Full Text Available The aim of this study was to evaluate microbial activity in soils under conventional and organic agricultural system management regimes. Soil samples were collected from plots under conventional management (CNV, organic management (ORG and native vegetation (AVN. Soil microbial activity and biomass was significantly greater in ORG compared with CNV. Soil bulk density decreased three years after adoption of organic system. Soil organic carbon (SOC was higher in the ORG than in the CNV. The soil under organic agricultural system presents higher microbial activity and biomass and lower bulk density than the conventional agricultural system.

  18. Stable carbon isotope depth profiles and soil organic carbon dynamics in the lower Mississippi Basin

    Science.gov (United States)

    Wynn, J.G.; Harden, J.W.; Fries, T.L.

    2006-01-01

    Analysis of depth trends of 13C abundance in soil organic matter and of 13C abundance from soil-respired CO2 provides useful indications of the dynamics of the terrestrial carbon cycle and of paleoecological change. We measured depth trends of 13C abundance from cropland and control pairs of soils in the lower Mississippi Basin, as well as the 13C abundance of soil-respired CO2 produced during approximately 1-year soil incubation, to determine the role of several candidate processes on the 13C depth profile of soil organic matter. Depth profiles of 13C from uncultivated control soils show a strong relationship between the natural logarithm of soil organic carbon concentration and its isotopic composition, consistent with a model Rayleigh distillation of 13C in decomposing soil due to kinetic fractionation during decomposition. Laboratory incubations showed that initially respired CO 2 had a relatively constant 13C content, despite large differences in the 13C content of bulk soil organic matter. Initially respired CO2 was consistently 13C-depleted with respect to bulk soil and became increasingly 13C-depleted during 1-year, consistent with the hypothesis of accumulation of 13C in the products of microbial decomposition, but showing increasing decomposition of 13C-depleted stable organic components during decomposition without input of fresh biomass. We use the difference between 13C / 12C ratios (calculated as ??-values) between respired CO 2 and bulk soil organic carbon as an index of the degree of decomposition of soil, showing trends which are consistent with trends of 14C activity, and with results of a two-pooled kinetic decomposition rate model describing CO2 production data recorded during 1 year of incubation. We also observed inconsistencies with the Rayleigh distillation model in paired cropland soils and reasons for these inconsistencies are discussed. ?? 2005 Elsevier B.V. All rights reserved.

  19. Linking measurements of biodegradability, thermal stability and chemical composition to evaluate the effects of management on soil organic matter

    Science.gov (United States)

    Gregorich, Ed; Gillespie, Adam; Beare, Mike; Curtin, Denis; Sanei, Hamed; Yanni, Sandra

    2015-04-01

    The stability of soil organic matter (SOM) as it relates to resistance to microbial degradation has important implications for nutrient cycling, emission of greenhouse gases, and C sequestration. Hence, there is interest in developing new ways to accurately quantify and characterise the labile and stable forms of soil organic C. Our objectives in this study were to evaluate and describe relationships among the biodegradability, thermal stability and chemistry of SOM in soil under widely contrasting management regimes. Samples from the same soil under permanent pasture, an arable cropping rotation, and chemical fallow were fractionated (sand: 2000-50 μm; silt: 50-5 μm, and clay: managements and that sand-associated organic matter was significantly more susceptible than that in the silt or clay fractions. Analysis by XANES showed accumulation of carboxylates and strong depletion of amides (protein) and aromatics in the fallow whole soil. Moreover, protein depletion was most significant in the sand fraction of the fallow soil. Sand fractions in fallow and cropped soils were, however, enriched in plant-derived phenols, aromatics and carboxylates compared to the sand fraction of pasture soils. In contrast, ketones, which have been identified as products of microbially-processed organic matter, were slightly enriched in the silt fraction of the pasture soil. These data suggest reduced inputs and cropping restrict the decomposition of plant residues and, without supplemental N additions, protein-N in native SOM is significantly mineralized in fallow systems to meet microbial C mineralization demands. Analytical pyrolysis showed distinct differences in the thermal stability of SOM among the size fractions and management treatments; it also showed that the loss of SOM generally involved dehydrogenation. The temperature at which half of the C was pyrolyzed showed strong correlation with mineralizable C and thus provides solid evidence for a link between the biological and

  20. Denitrification potential and its relation to organic carbon quality in three coastal wetland soils

    International Nuclear Information System (INIS)

    Dodla, Syam K.; Wang, Jim J.; DeLaune, Ron D.; Cook, Robert L.

    2008-01-01

    Capacity of a wetland to remove nitrate through denitrification is controlled by its physico-chemical and biological characteristics. Understanding these characteristics will help better to guide beneficial use of wetlands in processing nitrate. This study was conducted to determine the relationship between soil organic carbon (SOC) quality and denitrification rate in Louisiana coastal wetlands. Composite soil samples of different depths were collected from three different wetlands along a salinity gradient, namely, bottomland forest swamp (FS), freshwater marsh (FM), and saline marsh (SM) located in the Barataria Basin estuary. Potential denitrification rate (PDR) was measured by acetylene inhibition method and distribution of carbon (C) moieties in organic C was determined by 13 C solid-state NMR. Of the three wetlands, the FM soil profile exhibited the highest PDR on both unit weight and unit volume basis as compared to FS and SM. The FM also tended to yield higher amount of N 2 O as compared to the FS and SM especially at earlier stages of denitrification, suggesting incomplete reduction of NO 3 - at FM and potential for emission of N 2 O. Saline marsh soil profile had the lowest PDR on the unit volume basis. Increasing incubation concentration from 2 to 10 mg NO 3 - -N L -1 increased PDR by 2 to 6 fold with the highest increase in the top horizons of FS and SM soils. Regression analysis showed that across these three wetland systems, organic C has significant effect in regulating PDR. Of the compositional C moieties, polysaccharides positively influenced denitrification rate whereas phenolics (likely phenolic adehydes and ketonics) negatively affected denitrification rate in these wetland soils. These results could have significant implication in integrated assessment and management of wetlands for treating nutrient-rich biosolids and wastewaters, non-point source agricultural runoff, and nitrate found in the diverted Mississippi River water used for coastal

  1. High heterogeneity in soil composition and quality in different mangrove forests of Venezuela.

    Science.gov (United States)

    Otero, X L; Méndez, A; Nóbrega, G N; Ferreira, T O; Meléndez, W; Macías, F

    2017-09-18

    Mangrove forests play an important role in biogeochemical cycles of metals, nutrients, and C in coastal ecosystems. However, these functions could be strongly affected by the mangrove soil degradation. In this study, we performed an intensive sampling characterizing mangrove soils under different types of environment (lagoon/gulf) and vegetation (Rhizophora/Avicennia/dead mangrove) in the Venezuelan coast. To better understand the spatial heterogeneity of the composition and characteristics of the soils, a wide range of the soil attributes were analyzed. In general, the soils were anoxic (Eh mangroves presented a low Fe Pyrite content due to a limitation in the Fe oxyhydroxide contents, especially in soils with higher organic C content (TOC > 15%). Finally, the dead mangrove showed significantly lower amounts of TOC and fibers (in comparison to the well-preserved mangrove forest), which indicates that the C pools in mangrove soils are highly sensitive also to natural impact, such as ENSO.

  2. Ecological effects of combined pollution associated with e-waste recycling on the composition and diversity of soil microbial communities.

    Science.gov (United States)

    Liu, Jun; He, Xiao-Xin; Lin, Xue-Rui; Chen, Wen-Ce; Zhou, Qi-Xing; Shu, Wen-Sheng; Huang, Li-Nan

    2015-06-02

    The crude processing of electronic waste (e-waste) has led to serious contamination in soils. While microorganisms may play a key role in remediation of the contaminated soils, the ecological effects of combined pollution (heavy metals, polychlorinated biphenyls, and polybrominated diphenyl ethers) on the composition and diversity of microbial communities remain unknown. In this study, a suite of e-waste contaminated soils were collected from Guiyu, China, and the indigenous microbial assemblages were profiled by 16S rRNA high-throughput sequencing and clone library analysis. Our data revealed significant differences in microbial taxonomic composition between the contaminated and the reference soils, with Proteobacteria, Acidobacteria, Bacteroidetes, and Firmicutes dominating the e-waste-affected communities. Genera previously identified as organic pollutants-degrading bacteria, such as Acinetobacter, Pseudomonas, and Alcanivorax, were frequently detected. Canonical correspondence analysis revealed that approximately 70% of the observed variation in microbial assemblages in the contaminated soils was explained by eight environmental variables (including soil physiochemical parameters and organic pollutants) together, among which moisture content, decabromodiphenyl ether (BDE-209), and copper were the major factors. These results provide the first detailed phylogenetic look at the microbial communities in e-waste contaminated soils, demonstrating that the complex combined pollution resulting from improper e-waste recycling may significantly alter soil microbiota.

  3. Transformation of soil organic matter in a Japanese larch forest. Radiocarbon and stable carbon isotope compositions versus soil depth

    International Nuclear Information System (INIS)

    Liu Wei; Moriizumi, Jun; Yamazawa, Hiromi; Iida, Takao

    2008-01-01

    Soil organic matter at a depth of 0-55 cm, collected from a Japanese larch forest area, was separated into particulate organic matter (size >53 μm), particulate organic matter (size 14 C and δ 13 C values were determined. The Δ 14 C values of particulate matters decreased greatly from 128 per mille to -278 per mille, indicating a relative increase of resistant organic components in particulate matters. That of humic acid matter decreased from 183 per mille to -139 per mille. For these of organic matter fractions at the same depth, the Δ 14 C values of particulate matter (size >53μm) are smallest and those of humic acid matter are the largest. That indicates that a high contribution of young organic matter to the humic acid matter exists and transformation tendency of particulate matter may be from coarse to small in the particulate size. Positive Δ 14 C values appeared at a depth of 10 cm, 25 cm, and 35 cm for the particulate organic matter (size >53μm), particulate organic matter (size 14 C values of the humic acid matter also infects that the bomb carbon has reached the depth of 35 cm. Additionally, the Δ 14 C values of these three kinds of organic matters ranged from 50 per mille to 183 per mille at a depth of 0-7 cm, which were not smaller than that of litter in the forest area, indicating high proportion of modern, plants-derived soil organic matter in this depth ranges. The δ 13 C values increased from -28 per mille to -23 per mille with the increase depth of 0-55 cm. The δ 13 C values of humic acid matter are approximately less than that of particulate matters at the same depth, which may be explained as a high contribution of young organic matter to the humic acid matter. (author)

  4. Molecular composition of several soil organic matter fractions from anthropogenic black soils (Terra Preta de Índio) in Amazonia — A pyrolysis-GC/MS study

    NARCIS (Netherlands)

    Schellekens, Judith; Almeida-Santos, Taís; Macedo, Rodrigo Santana; Buurman, Peter; Kuyper, Thomas W.; Vidal-Torrado, Pablo

    2017-01-01

    The stability of soil organic matter (OM) in Amazonian anthropogenic soils, Terra Preta de Índio (TPI), is still not completely understood. The large contribution from black carbon (BC) and minerals to these soils is well-known; OM stability is therefore frequently explained by these properties,

  5. Short communication. Response of bacterial community composition to long-term applications of different composts in agricultural soils

    Energy Technology Data Exchange (ETDEWEB)

    Ros, M; Knapp, B A; Peintner, U; Insam, H

    2011-07-01

    Differences in the bacterial community composition of agricultural soils caused by a long-term (12 year) application of different composts were identified by cultivation-dependent and -independent methods (PCR-DGGE and 16S rRNA clone libraries). The number of colony forming units indicated that the successive incorporation of organic amendments increased the bacterial abundance (6.41-5.66 log10 cfu g-1dry soil) compared to control and mineral soils (5.54-3.74 log10 cfu g-1 dry soil). Isolated bacteria were dominated by Actinobacteria, whereby compost-amended soils and green compost-amended soils showed, respectively, higher number of members of Actinobacteria (100% and 64%) than control and mineral soils (50% and 40%). The 16S rRNA clone libraries were dominated by Proteobacteria (43%), Acidobacteria (21%) and Actinobacteria (13%). Proteobacteria and Actinobacteria were most abundant in compost amended soils while Acidobacteria were more frequently found in mineral fertilizer and control soils. Partial 16S rRNA gene clone libraries revealed a higher bacterial diversity than cultivation. In conclusion, we found differences of bacterial community composition with a cultivation approach and clone libraries between compost amended soils and control and mineral soil. (Author) 31 refs.

  6. Soil Fertility and Electrical Conductivity Affected by Organic Waste Rates and Nutrient Inputs

    Directory of Open Access Journals (Sweden)

    Davi Lopes do Carmo

    2016-01-01

    Full Text Available ABSTRACT The composition of organic waste (OW and its effect on soil processes may change soil fertility and electrical conductivity (EC. The side effects of waste use in crop fertilization are poorly understood for Brazilian soils. This study examined the effect of the addition of 15 different organic wastes to Oxisols and a Neosol on pH, base saturation, EC, cation exchange capacity (CEC at pH 7, and the availability of Al, macro (P, K, Ca2+, Mg2+ and S and micronutrients (B, Fe2+, Mn2+, Cu2+ and Zn2+. Soil samples (150 g were treated with chicken, pig, horse, cattle, and quail manures, sewage sludge 1 and 2, eucalyptus sawdust, plant substrate, coconut fiber, pine bark, coffee husk, peat, limed compost, and biochar. Wastes were added considering a fixed amount of C (2 g kg-1, which resulted in waste rates ranging from 2.5 to 25.6 Mg ha-1. The soil-waste mixtures were incubated for 330 days in laboratory conditions. The waste liming or acidification values were soil-dependent. The use of some manures and compost increased the pH to levels above of those considered adequate for plant growth. The soil EC was slightly increased in the Neosol and in the medium textured Oxisol, but it was sharply changed (from 195 to 394 µS cm-1 by the addition of organic wastes in the clayey Oxisol, although the EC values were below the range considered safe for plant growth. Changes in the soil availability of P, K+, Ca2+ and Zn2+ were highly related to the inputs of these nutrients by the wastes, and other factors in soil changed due to waste use. Organic waste use simultaneously affects different soil fertility attributes; thus, in addition to the target nutrient added to the soil, the soil acidity buffering capacity and the waste liming and agronomic value must be taken into account in the waste rate definition.

  7. Biochar Decelerates Soil Organic Nitrogen Cycling but Stimulates Soil Nitrification in a Temperate Arable Field Trial

    Science.gov (United States)

    Prommer, Judith; Wanek, Wolfgang; Hofhansl, Florian; Trojan, Daniela; Offre, Pierre; Urich, Tim; Schleper, Christa; Sassmann, Stefan; Kitzler, Barbara; Soja, Gerhard; Hood-Nowotny, Rebecca Clare

    2014-01-01

    Biochar production and subsequent soil incorporation could provide carbon farming solutions to global climate change and escalating food demand. There is evidence that biochar amendment causes fundamental changes in soil nutrient cycles, often resulting in marked increases in crop production, particularly in acidic and in infertile soils with low soil organic matter contents, although comparable outcomes in temperate soils are variable. We offer insight into the mechanisms underlying these findings by focusing attention on the soil nitrogen (N) cycle, specifically on hitherto unmeasured processes of organic N cycling in arable soils. We here investigated the impacts of biochar addition on soil organic and inorganic N pools and on gross transformation rates of both pools in a biochar field trial on arable land (Chernozem) in Traismauer, Lower Austria. We found that biochar increased total soil organic carbon but decreased the extractable organic C pool and soil nitrate. While gross rates of organic N transformation processes were reduced by 50–80%, gross N mineralization of organic N was not affected. In contrast, biochar promoted soil ammonia-oxidizer populations (bacterial and archaeal nitrifiers) and accelerated gross nitrification rates more than two-fold. Our findings indicate a de-coupling of the soil organic and inorganic N cycles, with a build-up of organic N, and deceleration of inorganic N release from this pool. The results therefore suggest that addition of inorganic fertilizer-N in combination with biochar could compensate for the reduction in organic N mineralization, with plants and microbes drawing on fertilizer-N for growth, in turn fuelling the belowground build-up of organic N. We conclude that combined addition of biochar with fertilizer-N may increase soil organic N in turn enhancing soil carbon sequestration and thereby could play a fundamental role in future soil management strategies. PMID:24497947

  8. Biochar decelerates soil organic nitrogen cycling but stimulates soil nitrification in a temperate arable field trial.

    Directory of Open Access Journals (Sweden)

    Judith Prommer

    Full Text Available Biochar production and subsequent soil incorporation could provide carbon farming solutions to global climate change and escalating food demand. There is evidence that biochar amendment causes fundamental changes in soil nutrient cycles, often resulting in marked increases in crop production, particularly in acidic and in infertile soils with low soil organic matter contents, although comparable outcomes in temperate soils are variable. We offer insight into the mechanisms underlying these findings by focusing attention on the soil nitrogen (N cycle, specifically on hitherto unmeasured processes of organic N cycling in arable soils. We here investigated the impacts of biochar addition on soil organic and inorganic N pools and on gross transformation rates of both pools in a biochar field trial on arable land (Chernozem in Traismauer, Lower Austria. We found that biochar increased total soil organic carbon but decreased the extractable organic C pool and soil nitrate. While gross rates of organic N transformation processes were reduced by 50-80%, gross N mineralization of organic N was not affected. In contrast, biochar promoted soil ammonia-oxidizer populations (bacterial and archaeal nitrifiers and accelerated gross nitrification rates more than two-fold. Our findings indicate a de-coupling of the soil organic and inorganic N cycles, with a build-up of organic N, and deceleration of inorganic N release from this pool. The results therefore suggest that addition of inorganic fertilizer-N in combination with biochar could compensate for the reduction in organic N mineralization, with plants and microbes drawing on fertilizer-N for growth, in turn fuelling the belowground build-up of organic N. We conclude that combined addition of biochar with fertilizer-N may increase soil organic N in turn enhancing soil carbon sequestration and thereby could play a fundamental role in future soil management strategies.

  9. Biochar decelerates soil organic nitrogen cycling but stimulates soil nitrification in a temperate arable field trial.

    Science.gov (United States)

    Prommer, Judith; Wanek, Wolfgang; Hofhansl, Florian; Trojan, Daniela; Offre, Pierre; Urich, Tim; Schleper, Christa; Sassmann, Stefan; Kitzler, Barbara; Soja, Gerhard; Hood-Nowotny, Rebecca Clare

    2014-01-01

    Biochar production and subsequent soil incorporation could provide carbon farming solutions to global climate change and escalating food demand. There is evidence that biochar amendment causes fundamental changes in soil nutrient cycles, often resulting in marked increases in crop production, particularly in acidic and in infertile soils with low soil organic matter contents, although comparable outcomes in temperate soils are variable. We offer insight into the mechanisms underlying these findings by focusing attention on the soil nitrogen (N) cycle, specifically on hitherto unmeasured processes of organic N cycling in arable soils. We here investigated the impacts of biochar addition on soil organic and inorganic N pools and on gross transformation rates of both pools in a biochar field trial on arable land (Chernozem) in Traismauer, Lower Austria. We found that biochar increased total soil organic carbon but decreased the extractable organic C pool and soil nitrate. While gross rates of organic N transformation processes were reduced by 50-80%, gross N mineralization of organic N was not affected. In contrast, biochar promoted soil ammonia-oxidizer populations (bacterial and archaeal nitrifiers) and accelerated gross nitrification rates more than two-fold. Our findings indicate a de-coupling of the soil organic and inorganic N cycles, with a build-up of organic N, and deceleration of inorganic N release from this pool. The results therefore suggest that addition of inorganic fertilizer-N in combination with biochar could compensate for the reduction in organic N mineralization, with plants and microbes drawing on fertilizer-N for growth, in turn fuelling the belowground build-up of organic N. We conclude that combined addition of biochar with fertilizer-N may increase soil organic N in turn enhancing soil carbon sequestration and thereby could play a fundamental role in future soil management strategies.

  10. About the possibility of obtaining cementitious soil composites of high strength on the basis of belozems of carbonate composition

    Science.gov (United States)

    Karapetyan, K. A.; Hayroyan, S. G.; Manukyan, E. S.

    2018-04-01

    The problem of manufacturing high strength cementitious soils based on belozems of carbonate composition, which experience compression (no less than 10 MPa), without application of surface active substances is considered. The portland cement of type 400 was used as a binding agent to develop compositions of cementitious soil composites, and the ordinary pipe water was used to obtain solutions of cementitious soils. The chemical and mineralogical composition of the initial ingredients and the granulometric composition of belozems were determined. The measurements showed that the upper and lower plasticity limits, the optimum moisture content, and the maximal density of the skeleton of belozems, as well as the considered compositions of cementitious soils, are insignificant, while the plasticity index of cementitious soils is less than one for belozems. It is experimentally proved that an increase in the portland cement amount lead to an increase in the compressive strength of cementitious soils with a decreasing speed. But for the same amount of portland cement used in the cementitious soil compositions, the values of the strength ratio of the pieces tested at the age of 60 and 28 days remain the same and are approximately equal to 1.2. A comparison of experimental data showed that it seems to be real to manufacture a cementitious soil on the basis of belozems of carbonate composition, which contain 10% of cement of the weight of dry mixture and have strength more than 10 MPa, without adding any surfactants to the material composition.

  11. Fertilization increases paddy soil organic carbon density*

    Science.gov (United States)

    Wang, Shao-xian; Liang, Xin-qiang; Luo, Qi-xiang; Fan, Fang; Chen, Ying-xu; Li, Zu-zhang; Sun, Huo-xi; Dai, Tian-fang; Wan, Jun-nan; Li, Xiao-jun

    2012-01-01

    Field experiments provide an opportunity to study the effects of fertilization on soil organic carbon (SOC) sequestration. We sampled soils from a long-term (25 years) paddy experiment in subtropical China. The experiment included eight treatments: (1) check, (2) PK, (3) NP, (4) NK, (5) NPK, (6) 7F:3M (N, P, K inorganic fertilizers+30% organic N), (7) 5F:5M (N, P, K inorganic fertilizers+50% organic N), (8) 3F:7M (N, P, K inorganic fertilizers+70% organic N). Fertilization increased SOC content in the plow layers compared to the non-fertilized check treatment. The SOC density in the top 100 cm of soil ranged from 73.12 to 91.36 Mg/ha. The SOC densities of all fertilizer treatments were greater than that of the check. Those treatments that combined inorganic fertilizers and organic amendments had greater SOC densities than those receiving only inorganic fertilizers. The SOC density was closely correlated to the sum of the soil carbon converted from organic amendments and rice residues. Carbon sequestration in paddy soils could be achieved by balanced and combined fertilization. Fertilization combining both inorganic fertilizers and organic amendments is an effective sustainable practice to sequestrate SOC. PMID:22467369

  12. Fertilization increases paddy soil organic carbon density.

    Science.gov (United States)

    Wang, Shao-xian; Liang, Xin-qiang; Luo, Qi-xiang; Fan, Fang; Chen, Ying-xu; Li, Zu-zhang; Sun, Huo-xi; Dai, Tian-fang; Wan, Jun-nan; Li, Xiao-jun

    2012-04-01

    Field experiments provide an opportunity to study the effects of fertilization on soil organic carbon (SOC) sequestration. We sampled soils from a long-term (25 years) paddy experiment in subtropical China. The experiment included eight treatments: (1) check, (2) PK, (3) NP, (4) NK, (5) NPK, (6) 7F:3M (N, P, K inorganic fertilizers+30% organic N), (7) 5F:5M (N, P, K inorganic fertilizers+50% organic N), (8) 3F:7M (N, P, K inorganic fertilizers+70% organic N). Fertilization increased SOC content in the plow layers compared to the non-fertilized check treatment. The SOC density in the top 100 cm of soil ranged from 73.12 to 91.36 Mg/ha. The SOC densities of all fertilizer treatments were greater than that of the check. Those treatments that combined inorganic fertilizers and organic amendments had greater SOC densities than those receiving only inorganic fertilizers. The SOC density was closely correlated to the sum of the soil carbon converted from organic amendments and rice residues. Carbon sequestration in paddy soils could be achieved by balanced and combined fertilization. Fertilization combining both inorganic fertilizers and organic amendments is an effective sustainable practice to sequestrate SOC.

  13. Soil moisture effects on the carbon isotope composition of soil respiration

    Science.gov (United States)

    Claire L. Phillips; Nick Nickerson; David Risk; Zachary E. Kayler; Chris Andersen; Alan Mix; Barbara J. Bond

    2010-01-01

    The carbon isotopic composition (δ13C) of recently assimilated plant carbon is known to depend on water-stress, caused either by low soil moisture or by low atmospheric humidity. Air humidity has also been shown to correlate with the δ13C of soil respiration, which suggests indirectly that recently fixed photosynthates...

  14. Soil organic carbon and nitrogen pools drive soil C-CO2 emissions from selected soils in Maritime Antarctica.

    Science.gov (United States)

    Pires, C V; Schaefer, C E R G; Hashigushi, A K; Thomazini, A; Filho, E I F; Mendonça, E S

    2017-10-15

    The ongoing trend of increasing air temperatures will potentially affect soil organic matter (SOM) turnover and soil C-CO 2 emissions in terrestrial ecosystems of Maritime Antarctica. The effects of SOM quality on this process remain little explored. We evaluated (i) the quantity and quality of soil organic matter and (ii) the potential of C release through CO 2 emissions in lab conditions in different soil types from Maritime Antarctica. Soil samples (0-10 and 10-20cm) were collected in Keller Peninsula and the vicinity of Arctowski station, to determine the quantity and quality of organic matter and the potential to emit CO 2 under different temperature scenarios (2, 5, 8 and 11°C) in lab. Soil organic matter mineralization is low, especially in soils with low organic C and N contents. Recalcitrant C form is predominant, especially in the passive pool, which is correlated with humic substances. Ornithogenic soils had greater C and N contents (reaching to 43.15gkg -1 and 5.22gkg -1 for total organic carbon and nitrogen, respectively). C and N were more present in the humic acid fraction. Lowest C mineralization was recorded from shallow soils on basaltic/andesites. C mineralization rates at 2°C were significant lower than at higher temperatures. Ornithogenic soils presented the lowest values of C-CO 2 mineralized by g of C. On the other hand, shallow soils on basaltic/andesites were the most sensitive sites to emit C-CO 2 by g of C. With permafrost degradation, soils on basaltic/andesites and sulfates are expected to release more C-CO 2 than ornithogenic soils. With greater clay contents, more protection was afforded to soil organic matter, with lower microbial activity and mineralization. The trend of soil temperature increases will favor C-CO 2 emissions, especially in the reduced pool of C stored and protected on permafrost, or in occasional Histosols. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Molecular composition of recycled organic wastes, as determined by solid-state {sup 13}C NMR and elemental analyses

    Energy Technology Data Exchange (ETDEWEB)

    Eldridge, S.M., E-mail: simon.eldridge@dpi.nsw.gov.au [Environmental Futures Centre, School of Environment, Griffith University, Nathan, QLD 4111 (Australia); NSW Department of Primary Industries, Bruxner Highway, Wollongbar, NSW 2477 (Australia); Chen, C.R. [Environmental Futures Centre, School of Environment, Griffith University, Nathan, QLD 4111 (Australia); Xu, Z.H. [Environmental Futures Centre, School of Biomolecular and Physical Sciences, Griffith University, Nathan, QLD 4111 (Australia); Nelson, P.N. [School of Earth and Environmental Sciences, James Cook University, Cairns, QLD 4870 (Australia); Boyd, S.E. [Environmental Futures Centre, School of Biomolecular and Physical Sciences, Griffith University, Nathan, QLD 4111 (Australia); Meszaros, I. [Formerly NSW Department of Primary Industries, Richmond, NSW 2753 (Australia); Chan, K.Y. [Graduate School of Environment, Macquarie University, North Ryde, NSW 2109 (Australia); Formerly NSW Department of Primary Industries, Richmond, NSW 2753 (Australia)

    2013-11-15

    Highlights: • Model estimated the molecular C components well for most RO wastes. • Molecular nature of organic matter in RO wastes varied widely. • Molecular composition by NMR modelling preferable to extraction techniques. • Some model shortcomings in estimating molecular composition of biochars. • Waste molecular composition important for carbon/nutrient outcomes in soil. - Abstract: Using solid state {sup 13}C NMR data and elemental composition in a molecular mixing model, we estimated the molecular components of the organic matter in 16 recycled organic (RO) wastes representative of the major materials generated in the Sydney basin area. Close correspondence was found between the measured NMR signal intensities and those predicted by the model for all RO wastes except for poultry manure char. Molecular nature of the organic matter differed widely between the RO wastes. As a proportion of organic C, carbohydrate C ranged from 0.07 to 0.63, protein C from <0.01 to 0.66, lignin C from <0.01 to 0.31, aliphatic C from 0.09 to 0.73, carbonyl C from 0.02 to 0.23, and char C from 0 to 0.45. This method is considered preferable to techniques involving imprecise extraction methods for RO wastes. Molecular composition data has great potential as a predictor of RO waste soil carbon and nutrient outcomes.

  16. Lability of soil organic carbon in tropical soils with different clay minerals

    DEFF Research Database (Denmark)

    Bruun, Thilde Bech; Elberling, Bo; Christensen, Bent Tolstrup

    2010-01-01

    Soil organic carbon (SOC) storage and turnover is influenced by interactions between organic matter and the mineral soil fraction. However, the influence of clay content and type on SOC turnover rates remains unclear, particularly in tropical soils under natural vegetation. We examined the lability...... of SOC in tropical soils with contrasting clay mineralogy (kaolinite, smectite, allophane and Al-rich chlorite). Soil was sampled from A horizons at six sites in humid tropical areas of Ghana, Malaysian Borneo and the Solomon Islands and separated into fractions above and below 250 µm by wet sieving....... Basal soil respiration rates were determined from bulk soils and soil fractions. Substrate induced respiration rates were determined from soil fractions. SOC lability was significantly influenced by clay mineralogy, but not by clay content when compared across contrasting clay minerals. The lability...

  17. Initial water repellency affected organic matter depletion rates of manure amended soils in Sri Lanka

    Directory of Open Access Journals (Sweden)

    Leelamanie D.A.L.

    2014-12-01

    . Hydrophobic protection may prevent rapid microbial decomposition of SOM and it is conceivable that hydrophobic substances in appropriate composition may reduce organic matter mineralization in soil. These results suggest the contribution of hydrophobic organic substances in bioresistance of SOM and their long-term accumulation in soils

  18. Pasture degradation modifies soil organic matter properties and biochemical functioning in Tibetan grasslands

    Science.gov (United States)

    Spielvogel, Sandra; Steingräber, Laura; Schleuß, Per; Kuzyakov, Yakov; Guggenberger, Georg

    2015-04-01

    Kobresia pastures of the Tibetan Plateau represent the world's largest alpine ecosystem. Moderate husbandry on Kobresia pastures is beneficial for the storage of soil organic carbon (OC), nitrogen (N) and other nutrients and prevents erosion by establishment of sedge-turf root mats with high OC allocation rates below ground. However, undisturbed root mats are affected by freezing and thawing processes, which cause initial ice cracks. As a consequence decomposition of root mat layers will be accelerated and current sedentarization programs with concomitant increased grazing intensity may additionally enhance root mat degradation. Finally, cracks are enlarged by water and wind erosion as well as pika activities until bare soil surface areas without root mat horizons occur. The aim of this study was to understand the impact of the root mat layer on soil organic carbon stabilization and microbial functioning depending on soil depths and to predict future changes (OC, N and nutrient losses, soil microbial functioning in SOM transformation) by overgrazing and climate change. We investigated the mineral soil below Kobresia root mats along a false time degradation sequence ranging from stage 1 (intact root mat) to stage 4 (mats with large cracks and bare soil patches). Vertical gradients of δ13C values, neutral sugar, cutin and suberin contents as well as microbial biomass estimated by total phospholipid fatty acid (PLFA), microbial community composition (PLFA profiles) and activities of six extracellular enzymes involved in the C, N, and P cycle were assessed. Soil OC and N contents as well as C/N ratios indicate an increasing illuviation of topsoil material into the subsoil with advancing root mat degradation. This was confirmed by more negative δ13C values as well as significantly (p ≤ 0.05) increasing contributions of cutin derived hydroxy fatty acids to OC in the subsoils from degradation stages 1 to 4. PLFA profiles were surprisingly similar in the subsoils of

  19. Changes in soil organic matter compositrion after introduction of riparian vegetation on shores of hydroelectric reservoires (Southeast of Brazil)

    NARCIS (Netherlands)

    Alcantara, de F.A.; Buurman, P.; Curi, N.; Furtini Neto, A.E.; Lagen, van B.; Meijer, E.M.

    2004-01-01

    This work is part of a research program with the general objective of evaluating soil sustainability in areas surrounding hydroelectric reservoirs, which have been planted with riparian forest. The specific aims were: (i) to assess if and how the soil organic matter (SOM) chemical composition has

  20. Long-term stabilization of crop residues and soil organic carbon affected by residue quality and initial soil pH.

    Science.gov (United States)

    Wang, Xiaojuan; Butterly, Clayton R; Baldock, Jeff A; Tang, Caixian

    2017-06-01

    Residues differing in quality and carbon (C) chemistry are presumed to contribute differently to soil pH change and long-term soil organic carbon (SOC) pools. This study examined the liming effect of different crop residues (canola, chickpea and wheat) down the soil profile (0-30cm) in two sandy soils differing in initial pH as well as the long-term stability of SOC at the amended layer (0-10cm) using mid-infrared (MIR) and solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy. A field column experiment was conducted for 48months. Chickpea- and canola-residue amendments increased soil pH at 0-10cm in the Podzol by up to 0.47 and 0.36units, and in the Cambisol by 0.31 and 0.18units, respectively, at 48months when compared with the non-residue-amended control. The decomposition of crop residues was greatly retarded in the Podzol with lower initial soil pH during the first 9months. The MIR-predicted particulate organic C (POC) acted as the major C sink for residue-derived C in the Podzol. In contrast, depletion of POC and recovery of residue C in MIR-predicted humic organic C (HOC) were detected in the Cambisol within 3months. Residue types showed little impact on total SOC and its chemical composition in the Cambisol at 48months, in contrast to the Podzol. The final HOC and resistant organic C (ROC) pools in the Podzol amended with canola and chickpea residues were about 25% lower than the control. This apparent priming effect might be related to the greater liming effect of these two residues in the Podzol. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Long-term variation in above and belowground plant inputs alters soil organic matter biogeochemistry at the molecular-level

    Science.gov (United States)

    Simpson, M. J.; Pisani, O.; Lin, L.; Lun, O.; Simpson, A.; Lajtha, K.; Nadelhoffer, K. J.

    2015-12-01

    The long-term fate of soil carbon reserves with global environmental change remains uncertain. Shifts in moisture, altered nutrient cycles, species composition, or rising temperatures may alter the proportions of above and belowground biomass entering soil. However, it is unclear how long-term changes in plant inputs may alter the composition of soil organic matter (SOM) and soil carbon storage. Advanced molecular techniques were used to assess SOM composition in mineral soil horizons (0-10 cm) after 20 years of Detrital Input and Removal Treatment (DIRT) at the Harvard Forest. SOM biomarkers (solvent extraction, base hydrolysis and cupric (II) oxide oxidation) and both solid-state and solution-state nuclear magnetic resonance (NMR) spectroscopy were used to identify changes in SOM composition and stage of degradation. Microbial activity and community composition were assessed using phospholipid fatty acid (PLFA) analysis. Doubling aboveground litter inputs decreased soil carbon content, increased the degradation of labile SOM and enhanced the sequestration of aliphatic compounds in soil. The exclusion of belowground inputs (No roots and No inputs) resulted in a decrease in root-derived components and enhanced the degradation of leaf-derived aliphatic structures (cutin). Cutin-derived SOM has been hypothesized to be recalcitrant but our results show that even this complex biopolymer is susceptible to degradation when inputs entering soil are altered. The PLFA data indicate that changes in soil microbial community structure favored the accelerated processing of specific SOM components with littler manipulation. These results collectively reveal that the quantity and quality of plant litter inputs alters the molecular-level composition of SOM and in some cases, enhances the degradation of recalcitrant SOM. Our study also suggests that increased litterfall is unlikely to enhance soil carbon storage over the long-term in temperate forests.

  2. The origin of soil organic matter controls its composition and bioreactivity across a mesic boreal forest latitudinal gradient

    Science.gov (United States)

    Kohl, L.; Philben, M. J.; Edwards, K. A.; Podrebarac, F. A.; Jamie, W.; Ziegler, S. E.

    2017-12-01

    Warmer climates have been associated with reduced soil organic matter (SOM) bioreactivity, lower respiration rates at a given temperature, which is typically attributed to the presence of more decomposed SOM. Cross site studies, however, indicate that ecosystem regime shifts associated with long-term climate warming can affect SOM properties through changes in vegetation and plant litter inputs to soils. The relative importance of these two controls, diagenesis and inputs, on SOM properties as ecosystems experience climate warming remains poorly understood. To address this, we characterized the elemental, chemical (nuclear magnetic resonance spectroscopy and total hydrolysable amino acids), and isotopic composition of plant litter and SOM across a well-constrained mesic boreal forest latitudinal transect in Atlantic Canada. Results across forest sites within each of three climate regions indicated that (1) climate history and diagenesis affect distinct parameters of SOM chemistry, (2) increases in SOM bioreactivity with latitude were associated with elevated proportions of carbohydrates relative to plant waxes and lignin, and (3) despite the common forest type across regions, differences in SOM chemistry by climate region were associated with chemically distinct litter inputs and not different degrees of diagenesis. Climate effects on vascular plant litter chemistry explained only part of the regional differences in SOM chemistry, most notably the higher protein content of SOM from warmer regions. Greater proportions of lignin and aliphatic compounds and smaller proportions of carbohydrates in warmer sites' soils were explained by the higher proportion of vascular plant relative to moss litter in the warmer forests. These results indicate that a climate induced decrease in the proportion of moss inputs will not only impact SOM chemistry but also increase the resistance of SOM to decomposition, thus significantly altering SOM cycling in these boreal forest soils.

  3. Dissolved organic carbon and nitrogen release from boreal Holocene permafrost and seasonally frozen soils of Alaska

    Science.gov (United States)

    Wickland, Kimberly P.; Waldrop, Mark P.; Aiken, George R.; Koch, Joshua C.; Torre Jorgenson, M.; Striegl, Robert G.

    2018-06-01

    Permafrost (perennially frozen) soils store vast amounts of organic carbon (C) and nitrogen (N) that are vulnerable to mobilization as dissolved organic carbon (DOC) and dissolved organic and inorganic nitrogen (DON, DIN) upon thaw. Such releases will affect the biogeochemistry of permafrost regions, yet little is known about the chemical composition and source variability of active-layer (seasonally frozen) and permafrost soil DOC, DON and DIN. We quantified DOC, total dissolved N (TDN), DON, and DIN leachate yields from deep active-layer and near-surface boreal Holocene permafrost soils in interior Alaska varying in soil C and N content and radiocarbon age to determine potential release upon thaw. Soil cores were collected at three sites distributed across the Alaska boreal region in late winter, cut in 15 cm thick sections, and deep active-layer and shallow permafrost sections were thawed and leached. Leachates were analyzed for DOC, TDN, nitrate (NO3 ‑), and ammonium (NH4 +) concentrations, dissolved organic matter optical properties, and DOC biodegradability. Soils were analyzed for C, N, and radiocarbon (14C) content. Soil DOC, TDN, DON, and DIN yields increased linearly with soil C and N content, and decreased with increasing radiocarbon age. These relationships were significantly different for active-layer and permafrost soils such that for a given soil C or N content, or radiocarbon age, permafrost soils released more DOC and TDN (mostly as DON) per gram soil than active-layer soils. Permafrost soil DOC biodegradability was significantly correlated with soil Δ14C and DOM optical properties. Our results demonstrate that near-surface Holocene permafrost soils preserve greater relative potential DOC and TDN yields than overlying seasonally frozen soils that are exposed to annual leaching and decomposition. While many factors control the fate of DOC and TDN, the greater relative yields from newly thawed Holocene permafrost soils will have the largest

  4. Carbon nanomaterials alter plant physiology and soil bacterial community composition in a rice-soil-bacterial ecosystem.

    Science.gov (United States)

    Hao, Yi; Ma, Chuanxin; Zhang, Zetian; Song, Youhong; Cao, Weidong; Guo, Jing; Zhou, Guopeng; Rui, Yukui; Liu, Liming; Xing, Baoshan

    2018-01-01

    The aim of this study was to compare the toxicity effects of carbon nanomaterials (CNMs), namely fullerene (C 60 ), reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs), on a mini-ecosystem of rice grown in a loamy potted soil. We measured plant physiological and biochemical parameters and examined bacterial community composition in the CNMs-treated plant-soil system. After 30 days of exposure, all the three CNMs negatively affected the shoot height and root length of rice, significantly decreased root cortical cells diameter and resulted in shrinkage and deformation of cells, regardless of exposure doses (50 or 500 mg/kg). Additionally, at the high exposure dose of CNM, the concentrations of four phytohormones, including auxin, indoleacetic acid, brassinosteroid and gibberellin acid 4 in rice roots significantly increased as compared to the control. At the high exposure dose of MWCNTs and C 60 , activities of the antioxidant enzymes superoxide dismutase (SOD) and peroxidase (POD) in roots increased significantly. High-throughput sequencing showed that three typical CNMs had little effect on shifting the predominant soil bacterial species, but the presence of CNMs significantly altered the composition of the bacterial community. Our results indicate that different CNMs indeed resulted in environmental toxicity to rice and soil bacterial community in the rhizosphere and suggest that CNMs themselves and their incorporated products should be reasonably used to control their release/discharge into the environment to prevent their toxic effects on living organisms and the potential risks to food safety. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Soil microbial community composition is correlated to soil carbon processing along a boreal wetland formation gradient

    Science.gov (United States)

    Chapman, Eric; Cadillo-Quiroz, Hinsby; Childers, Daniel L.; Turetsky, Merritt R.; Waldrop, Mark P.

    2017-01-01

    Climate change is modifying global biogeochemical cycles. Microbial communities play an integral role in soil biogeochemical cycles; knowledge about microbial composition helps provide a mechanistic understanding of these ecosystem-level phenomena. Next generation sequencing approaches were used to investigate changes in microbial functional groups during ecosystem development, in response to climate change, in northern boreal wetlands. A gradient of wetlands that developed following permafrost degradation was used to characterize changes in the soil microbial communities that mediate C cycling: a bog representing an “undisturbed” system with intact permafrost, and a younger bog and an older bog that formed following the disturbance of permafrost thaw. Reference 16S rRNA databases and several diversity indices were used to assess structural differences among these communities, to assess relationships between soil microbial community composition and various environmental variables including redox potential and pH. Rates of potential CO2 and CH4 gas production were quantified to correlate sequence data with gas flux. The abundance of organic C degraders was highest in the youngest bog, suggesting higher rates of microbial processes, including potential CH4 production. In addition, alpha diversity was also highest in the youngest bog, which seemed to be related to a more neutral pH and a lower redox potential. These results could potentially be driven by increased niche differentiation in anaerobic soils. These results suggest that ecosystem structure, which was largely driven by changes in edaphic and plant community characteristics between the “undisturbed” permafrost bog and the two bogs formed following permafrost thaw, strongly influenced microbial function.

  6. Carbon storage in soil: how different land uses affect particulate organic matter composition. A molecular approach using nuclear magnetic resonance spectroscopy.

    Science.gov (United States)

    Panettieri, Marco; Courtier-Murias, Denis; Rumpel, Cornelia; Dignac, Marie-France; Doumert, Bertrand; Chabbi, Abad

    2017-04-01

    The future soil carbon stocks in a climate change scenario is being closely monitored. However, the huge edaphoclimatic variability impedes to disclose the mechanisms which underlie the cycle of accumulation/mineralization of soil organic matter (SOM). Soil environment could be described as a complex three phases matrix in which gases, liquids, and solids are not uniformly mixed, and in which microbes, fungi, vegetal residues, and roots are continuously interacting with the soil matrix and with each other. Molecular analyses on soil samples are crucial to estimate how stable those pools are and to predict which practices may accumulate larger C stocks. However, the study of land use impact through molecular characterization of a complex mixture like SOM is a challenge that requires a multidisciplinary approach. The present study applied a combination of soil physical fractionation (separation by density of the particulate organic matter (POM) within water stable aggregate fractions) followed by nuclear magnetic resonance (NMR) spectroscopy as a way to overcome spatial variability and to quantify the changes in the composition of SOM induced by land-use changes. The objective of the study was to assess, at a molecular level, the impact of different land managements, i.e. the introduction of temporary (ley) grassland into cropping cycles, on the chemical composition of SOM. Soil samples were collected at the long-term experimental observatory in Lusignan (http://www.soere-acbb.com/), in which control plots under permanent grassland, permanent cropland, and bare fallow are part of the experiment. To improve the signal-to-noise ratio (especially in the aromatic-C region), samples were analyzed using a ramped cross polarization-single pulse/magic angle spinning (CPSP/MAS) experiment. Peak integrals of different spectral regions (indicating different compound classes) were compared between treatments and two different molecular mixing models, calibrated against standard

  7. Biologically Active Organic Matter in Soils of European Russia

    Science.gov (United States)

    Semenov, V. M.; Kogut, B. M.; Zinyakova, N. B.; Masyutenko, N. P.; Malyukova, L. S.; Lebedeva, T. N.; Tulina, A. S.

    2018-04-01

    Experimental and literature data on the contents and stocks of active organic matter in 200 soil samples from the forest-tundra, southern-taiga, deciduous-forest, forest-steppe, dry-steppe, semidesert, and subtropical zones have been generalized. Natural lands, agrocenoses, treatments of long-term field experiments (bare fallow, unfertilized and fertilized crop rotations, perennial plantations), and different layers of soil profile are presented. Sphagnum peat and humus-peat soil in the tundra and forest-tundra zones are characterized by a very high content of active organic matter (300-600 mg C/100 g). Among the zonal soils, the content of active organic matter increases from the medium (75-150 mg C/100 g) to the high (150-300 mg C/100 g) level when going from soddy-podzolic soil to gray forest and dark-gray forest soils and then to leached chernozem. In the series from typical chernozem to ordinary and southern chernozem and chestnut and brown semidesert soils, a decrease in the content of active organic matter to the low (35-75 mg C/100 g) and very low (organic matter. Most arable soils are mainly characterized by low or very low contents of active organic matter. In the upper layers of soils, active organic matter makes up 1.2-11.1% of total Corg. The profile distribution of active organic matter in the studied soils coincides with that of Corg: their contents appreciably decrease with depth, except for brown semidesert soil. The stocks of active organic matter vary from 0.4 to 5.4 t/ha in the layer of 0-20 cm and from 1.0 to 12.4/ha in the layer of 0-50 cm of different soil types.

  8. Modeling the influence of organic acids on soil weathering

    Science.gov (United States)

    Lawrence, Corey R.; Harden, Jennifer W.; Maher, Kate

    2014-01-01

    Biological inputs and organic matter cycling have long been regarded as important factors in the physical and chemical development of soils. In particular, the extent to which low molecular weight organic acids, such as oxalate, influence geochemical reactions has been widely studied. Although the effects of organic acids are diverse, there is strong evidence that organic acids accelerate the dissolution of some minerals. However, the influence of organic acids at the field-scale and over the timescales of soil development has not been evaluated in detail. In this study, a reactive-transport model of soil chemical weathering and pedogenic development was used to quantify the extent to which organic acid cycling controls mineral dissolution rates and long-term patterns of chemical weathering. Specifically, oxalic acid was added to simulations of soil development to investigate a well-studied chronosequence of soils near Santa Cruz, CA. The model formulation includes organic acid input, transport, decomposition, organic-metal aqueous complexation and mineral surface complexation in various combinations. Results suggest that although organic acid reactions accelerate mineral dissolution rates near the soil surface, the net response is an overall decrease in chemical weathering. Model results demonstrate the importance of organic acid input concentrations, fluid flow, decomposition and secondary mineral precipitation rates on the evolution of mineral weathering fronts. In particular, model soil profile evolution is sensitive to kaolinite precipitation and oxalate decomposition rates. The soil profile-scale modeling presented here provides insights into the influence of organic carbon cycling on soil weathering and pedogenesis and supports the need for further field-scale measurements of the flux and speciation of reactive organic compounds.

  9. The Role of Microbial Community Composition in Controlling Soil Respiration Responses to Temperature.

    Science.gov (United States)

    Auffret, Marc D; Karhu, Kristiina; Khachane, Amit; Dungait, Jennifer A J; Fraser, Fiona; Hopkins, David W; Wookey, Philip A; Singh, Brajesh K; Freitag, Thomas E; Hartley, Iain P; Prosser, James I

    2016-01-01

    Rising global temperatures may increase the rates of soil organic matter decomposition by heterotrophic microorganisms, potentially accelerating climate change further by releasing additional carbon dioxide (CO2) to the atmosphere. However, the possibility that microbial community responses to prolonged warming may modify the temperature sensitivity of soil respiration creates large uncertainty in the strength of this positive feedback. Both compensatory responses (decreasing temperature sensitivity of soil respiration in the long-term) and enhancing responses (increasing temperature sensitivity) have been reported, but the mechanisms underlying these responses are poorly understood. In this study, microbial biomass, community structure and the activities of dehydrogenase and β-glucosidase enzymes were determined for 18 soils that had previously demonstrated either no response or varying magnitude of enhancing or compensatory responses of temperature sensitivity of heterotrophic microbial respiration to prolonged cooling. The soil cooling approach, in contrast to warming experiments, discriminates between microbial community responses and the consequences of substrate depletion, by minimising changes in substrate availability. The initial microbial community composition, determined by molecular analysis of soils showing contrasting respiration responses to cooling, provided evidence that the magnitude of enhancing responses was partly related to microbial community composition. There was also evidence that higher relative abundance of saprophytic Basidiomycota may explain the compensatory response observed in one soil, but neither microbial biomass nor enzymatic capacity were significantly affected by cooling. Our findings emphasise the key importance of soil microbial community responses for feedbacks to global change, but also highlight important areas where our understanding remains limited.

  10. Organic matter dynamics and N mineralization in grassland soils

    NARCIS (Netherlands)

    Hassink, J.

    1995-01-01


    The aims of this study are i) to improve our understanding of the interactions between soil texturelsoil structure, soil organic matter, soil biota and mineralization in grassland soils, ii) to develop a procedure that yields soil organic matter fractions that can be determined directly

  11. Soil organic matter stabilization in buried paleosols of the Great Plains

    Science.gov (United States)

    Chaopricha, N. T.; Marin-Spiotta, E.; Mason, J. A.; Mueller, C. W.

    2010-12-01

    Understanding the mechanisms that control soil organic matter (SOM) stabilization is important for understanding how soil carbon is sequestered over millennia, and for predicting how future disturbances may affect soil carbon stocks. We are studying the mechanisms controlling SOM stabilization in the Brady Soil, a buried paleosol in Holocene loess deposits spanning much of the central Great Plains of the United States. The Brady Soil developed 9,000-13,500 years ago during a time of warming and drying that resulted in a shift from C3 to C4 dominated plants. The Brady soil is unusual in that it has very dark coloring, although it contains less than separate particulate organic matter associated with minerals from that within and outside of soil aggregates. We found the largest and darkest amounts of organic C in aggregate-protected SOM greater than 20 µm in diameter. Density and textural fractionation revealed that much of the SOM is bound within aggregates, indicating that protection within aggregates is a major contributor to SOM- stabilization in the Brady Soil. We are conducting a long-term lab soil incubation with soils collected from the modern A horizon and the Brady Soil to determine if the buried SOM becomes microbially available when exposed to the modern atmosphere. We are measuring potential rates of respiration and production of CH4 and N2O. Results so far show respiration rates at field moisture for both modern and buried horizons are limited by water, suggesting dry environmental conditions may have helped to preserve SOM in the Brady Soil. We are investigating the potential for chemical stabilization of the dark SOM preserved in the buried paleosol by characterizing C chemistry using solid-state 13C-NMR spectroscopy. Furthermore, we plan to use lipid analyses and pyrolysis GC/MS to determine likely sources for the SOM: microbial vs plant. Combining information on the physical location of SOM in the soil, its chemical composition, decomposability

  12. Observed effects of soil organic matter content on the microwave emissivity of soils

    International Nuclear Information System (INIS)

    O'Neill, P.E.; Jackson, T.J.

    1990-01-01

    In order to determine the significance of organic matter content on the microwave emissivity of soils when estimating soil moisture, a series of field experiments were conducted in which 1.4 GHz microwave emissivity data were collected over test plots of sandy loam soil with different organic matter levels (1.8%, 4.0%, and 6.1%) for a range of soil moisture values. Analyses of the observed data showed only minor variation in microwave emissivity due to a change in organic matter content at a given moisture level for soils with similar texture and structure. Predictions of microwave emissivity made using a dielectric model for aggregated soils exhibited the same trends and type of response as the measured data when adjusted values for the input parameters were utilized

  13. Stocks of organic carbon in Estonian soils

    Directory of Open Access Journals (Sweden)

    Kõlli, Raimo

    2009-06-01

    Full Text Available The soil organic carbon (SOC stocks (Mg ha–1 ofautomorphic mineral (9 soil groups, hydromorphic mineral (7, and lowland organic soils (4 are given for the soil cover or solum layer as a whole and also for its epipedon (topsoil layer. The SOC stocks for forest, arable lands, and grasslands and for the entire Estonian soil cover were calculated on the basis of the mean SOC stock and distribution area of the respective soil type. In the Estonian soil cover (42 400 km2, a total of 593.8 ± 36.9 Tg of SOC is retained, with 64.9% (385.3 ± 27.5 Tg in the epipedon layer (O, H, and A horizons and 35.1% in the subsoil (B and E horizons. The pedo-ecological regularities of SOC retention in soils are analysed against the background of the Estonian soil ordination net.

  14. The effect of feed water dissolved organic carbon concentration and composition on organic micropollutant removal and microbial diversity in soil columns simulating river bank filtration.

    Science.gov (United States)

    Bertelkamp, C; van der Hoek, J P; Schoutteten, K; Hulpiau, L; Vanhaecke, L; Vanden Bussche, J; Cabo, A J; Callewaert, C; Boon, N; Löwenberg, J; Singhal, N; Verliefde, A R D

    2016-02-01

    This study investigated organic micropollutant (OMP) biodegradation rates in laboratory-scale soil columns simulating river bank filtration (RBF) processes. The dosed OMP mixture consisted of 11 pharmaceuticals, 6 herbicides, 2 insecticides and 1 solvent. Columns were filled with soil from a RBF site and were fed with four different organic carbon fractions (hydrophilic, hydrophobic, transphilic and river water organic matter (RWOM)). Additionally, the effect of a short-term OMP/dissolved organic carbon (DOC) shock-load (e.g. quadrupling the OMP concentrations and doubling the DOC concentration) on OMP biodegradation rates was investigated to assess the resilience of RBF systems. The results obtained in this study imply that - in contrast to what is observed for managed aquifer recharge systems operating on wastewater effluent - OMP biodegradation rates are not affected by the type of organic carbon fraction fed to the soil column, in case of stable operation. No effect of a short-term DOC shock-load on OMP biodegradation rates between the different organic carbon fractions was observed. This means that the RBF site simulated in this study is resilient towards transient higher DOC concentrations in the river water. However, a temporary OMP shock-load affected OMP biodegradation rates observed for the columns fed with the river water organic matter (RWOM) and the hydrophilic fraction of the river water organic matter. These different biodegradation rates did not correlate with any of the parameters investigated in this study (cellular adenosine triphosphate (cATP), DOC removal, specific ultraviolet absorbance (SUVA), richness/evenness of the soil microbial population or OMP category (hydrophobicity/charge). Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Increased nitrogen availability counteracts climatic change feedback from increased temperature on boreal forest soil organic matter degradation

    Science.gov (United States)

    Erhagen, Bjorn; Nilsson, Mats; Oquist, Mats; Ilstedt, Ulrik; Sparrman, Tobias; Schleucher, Jurgen

    2014-05-01

    Over the last century, the greenhouse gas concentrations in the atmosphere have increased dramatically, greatly exceeding pre-industrial levels that had prevailed for the preceding 420 000 years. At the same time the annual anthropogenic contribution to the global terrestrial nitrogen cycle has increased and currently exceeds natural inputs. Both temperature and nitrogen levels have profound effects on the global carbon cycle including the rate of organic matter decomposition, which is the most important biogeochemical process that returns CO2 to the atmosphere. Here we show for the first time that increasing the availability of nitrogen not only directly affects the rate of organic matter decomposition but also significantly affects its temperature dependence. We incubated litter and soil organic matter from a long-term (40 years) nitrogen fertilization experiment in a boreal Scots pine (Pinus silvestris L.) forest at different temperatures and determined the temperature dependence of the decomposition of the sample's organic matter in each case. Nitrogen fertilization did not affect the temperature sensitivity (Q10) of the decomposition of fresh plant litter but strongly reduced that for humus soil organic matter. The Q10 response of the 0-3 cm soil layer decreased from 2.5±0.35 to an average of 1.9±0.21 over all nitrogen treatments, and from 2.2±0.19 to 1.6±0.16 in response to the most intense nitrogen fertilization treatment in the 4-7 cm soil layer. Long-term nitrogen additions also significantly affected the organic chemical composition (as determined by 13C CP-MAS NMR spectroscopy) of the soil organic matter. These changes in chemical composition contributed significantly (p<0.05) to the reduced Q10 response. These new insights into the relationship between nitrogen availability and the temperature sensitivity of organic matter decomposition will be important for understanding and predicting how increases in global temperature and rising anthropogenic

  16. Long-term citrus organic farming strategy results in soil organic matter recovery

    Science.gov (United States)

    Novara, Agata; Pereira, Paulo; Barone, Ettore; Giménez Morera, Antonio; Keesstra, Saskia; Gristina, Luciano; Jordán, Antonio; Parras-Alcantara, Luis; Cerdà, Artemi

    2017-04-01

    ABSTRACT Soils play a key role in the Earth System (Keesstra et al., 2012; Brevick et al., 2015). Soils are a key resource for the human societies (Mol and Keesstra, 2012) and they are relevant to achieve the sustainability such as the United Nations Goals highlight (Keesstra et al., 2016). Agriculture soils, especially those under conventional tillage, are prone to organic matter mineralization, soil erosion, compaction and increase of greenhouse gases emission (Novara et al., 2011; Bruun et al., 2015; de Moraes et al., 2015; Choudhury et al., 2016; del Mar et al., 2016). The adoption of organic farming and sustainable management practices may provide a sustainable crop productivity, and in the meanwhile mitigate the negative impact of agriculture on ecosystem services benefits (Laudicina et al., 2015; Parras-Alcantara et al., 2015; 2016). The aim of this study was to examine, under field conditions, the long-term changes of soil organic matter under organic farming management in citrus orchards in Mediterranean environment and evaluate the ecosystem service on C sequestration in terms of economic benefits. The research was carried out at the Alcoleja Experimental Station located in the Cànyoles river watershed in the Eastern Spain on 45year old citrus plantation. Soil Organic Matter (SOM) content was monitored for 20 years at 6 different soil depth. The profitability of citrus plantation was estimated under conventional and organic management. Results showed that SOM in the 0-30 cm soil depth was the double after 20 years of organic farming management, ranging from 0.8 g kg-1 in 1995 to 1.5 g kg-1 in 2006. The highest SOM increase was in the top soil layer (368% of SOM increase in comparison to the initial SOM content) and decreased with soil depth. The effect of organic farming was relevant after 5 years since land management change, indicating that in Mediterranean environment the duration of long term studies should be higher than five years and proper policy

  17. Development of a composite soil degradation assessment index for cocoa agroecosystems in southwestern Nigeria

    Science.gov (United States)

    Adenrele Adeniyi, Sunday; de Clercq, Willem Petrus; van Niekerk, Adriaan

    2017-08-01

    Cocoa agroecosystems are a major land-use type in the tropical rainforest belt of West Africa, reportedly associated with several ecological changes, including soil degradation. This study aims to develop a composite soil degradation assessment index (CSDI) for determining the degradation level of cocoa soils under smallholder agroecosystems of southwestern Nigeria. Plots where natural forests have been converted to cocoa agroecosystems of ages 1-10, 11-40, and 41-80 years, respectively representing young cocoa plantations (YCPs), mature cocoa plantations (MCPs), and senescent cocoa plantations (SCPs), were identified to represent the biological cycle of the cocoa tree. Soil samples were collected at a depth of 0 to 20 cm in each plot and analysed in terms of their physical, chemical, and biological properties. Factor analysis of soil data revealed four major interacting soil degradation processes: decline in soil nutrients, loss of soil organic matter, increase in soil acidity, and the breakdown of soil textural characteristics over time. These processes were represented by eight soil properties (extractable zinc, silt, soil organic matter (SOM), cation exchange capacity (CEC), available phosphorus, total porosity, pH, and clay content). These soil properties were subjected to forward stepwise discriminant analysis (STEPDA), and the result showed that four soil properties (extractable zinc, cation exchange capacity, SOM, and clay content) are the most useful in separating the studied soils into YCP, MCP, and SCP. In this way, we have sufficiently eliminated redundancy in the final selection of soil degradation indicators. Based on these four soil parameters, a CSDI was developed and used to classify selected cocoa soils into three different classes of degradation. The results revealed that 65 % of the selected cocoa farms are moderately degraded, while 18 % have a high degradation status. The numerical value of the CSDI as an objective index of soil degradation

  18. The Effect of Climate change on Soil Organic Matter Decomposition

    OpenAIRE

    TÓTH, János Attila; LAJTHA, Kate; BOWDEN, Richard; KOTROCZÓ, Zsolt; KRAKOMPERGER, Zsolt; CALDWELL, Bruce; PAPP, Mária

    2007-01-01

    In the last few decades the climate of Síkfkút ILTER Forest (Hungary) became warmerand dryer. Due to the climate change the species composition of forest has been changing, and thetotal leaf litter production has been slightly decreasing. According to our long-term litter manipulationfield experiment, which is part of ILTER Detritus Input and Removal Treatments (DIRT) Project, aftera 4-5 year treating period, at the No Litter, No Root and No Input treatments the soil organic C and Ncontent, t...

  19. Enzyme activities by indicator of quality in organic soil

    Science.gov (United States)

    Raigon Jiménez, Mo; Fita, Ana Delores; Rodriguez Burruezo, Adrián

    2016-04-01

    The analytical determination of biochemical parameters, as soil enzyme activities and those related to the microbial biomass is growing importance by biological indicator in soil science studies. The metabolic activity in soil is responsible of important processes such as mineralization and humification of organic matter. These biological reactions will affect other key processes involved with elements like carbon, nitrogen and phosphorus , and all transformations related in soil microbial biomass. The determination of biochemical parameters is useful in studies carried out on organic soil where microbial processes that are key to their conservation can be analyzed through parameters of the metabolic activity of these soils. The main objective of this work is to apply analytical methodologies of enzyme activities in soil collections of different physicochemical characteristics. There have been selective sampling of natural soils, organic farming soils, conventional farming soils and urban soils. The soils have been properly identified conserved at 4 ° C until analysis. The enzyme activities determinations have been: catalase, urease, cellulase, dehydrogenase and alkaline phosphatase, which bring together a representative group of biological transformations that occur in the soil environment. The results indicate that for natural and agronomic soil collections, the values of the enzymatic activities are within the ranges established for forestry and agricultural soils. Organic soils are generally higher level of enzymatic, regardless activity of the enzyme involved. Soil near an urban area, levels of activities have been significantly reduced. The vegetation cover applied to organic soils, results in greater enzymatic activity. So the quality of these soils, defined as the ability to maintain their biological productivity is increased with the use of cover crops, whether or spontaneous species. The practice of cover based on legumes could be used as an ideal choice

  20. Using soil organic matter fractions as indicators of soil physical quality

    DEFF Research Database (Denmark)

    Pulido Moncada, Mansonia A.; Lozano, Z; Delgado, M

    2018-01-01

    The objective of this study was to evaluate the use of chemical and physical fractions of soil organic matter (SOM), rather than SOM per se, as indicators of soil physical quality (SPQ) based on their effect on aggregate stability (AS). Chemically extracted humic and fulvic acids (HA and FA) were...... used as chemical fractions, and heavy and light fractions (HF and LF) obtained by density separation as physical fractions. The analyses were conducted on medium-textured soils from tropical and temperate regions under cropland and pasture. Results show that soil organic carbon (SOC), SOM fractions...... and AS appear to be affected by land use regardless of the origin of the soils. A general separation of structurally stable and unstable soils between samples of large and small SOC content, respectively, was observed. SOM fractions did not show a better relationship with AS than SOC per se. In both...

  1. [Priming effect of biochar on the minerialization of native soil organic carbon and the mechanisms: A review.

    Science.gov (United States)

    Chen, Ying; Liu, Yu Xue; Chen, Chong Jun; Lyu, Hao Hao; Wa, Yu Ying; He, Li Li; Yang, Sheng Mao

    2018-01-01

    In recent years, studies on carbon sequestration of biochar in soil has been in spotlight owing to the specific characteristics of biochar such as strong carbon stability and well developed pore structure. However, whether biochar will ultimately increase soil carbon storage or promote soil carbon emissions when applied into the soil? This question remains controversial in current academic circles. Further research is required on priming effect of biochar on mineralization of native soil organic carbon and its mechanisms. Based on the analysis of biochar characteristics, such as its carbon composition and stability, pore structure and surface morphology, research progress on the priming effect of biochar on the decomposition of native soil organic carbon was reviewed in this paper. Furthermore, possible mechanisms of both positive and negative priming effect, that is promoting and suppressing the mineralization, were put forward. Positive priming effect is mainly due to the promotion of soil microbial activity caused by biochar, the preferential mineralization of easily decomposed components in biochar, and the co-metabolism of soil microbes. While negative priming effect is mainly based on the encapsulation and adsorption protection of soil organic matter due to the internal pore structure and the external surface of biochar. Other potential reasons for negative priming effect can be the stabilization resulted from the formation of organic-inorganic complex promoted by biochar in the soil, and the inhibition of activity of soil microbes and its enzymes by biochar. Finally, future research directions were proposed in order to provide theoretical basis for the application of biochar in soil carbon sequestration.

  2. Particulate Organic Matter Affects Soil Nitrogen Mineralization under Two Crop Rotation Systems.

    Directory of Open Access Journals (Sweden)

    Rongyan Bu

    Full Text Available Changes in the quantity and/or quality of soil labile organic matter between and after different types of cultivation system could play a dominant role in soil nitrogen (N mineralization. The quantity and quality of particulate organic matter (POM and potentially mineralizable-N (PMN contents were measured in soils from 16 paired rice-rapeseed (RR/cotton-rapeseed (CR rotations sites in Hubei province, central China. Then four paired soils encompassing low (10th percentile, intermediate (25th and 75th percentiles, and high (90th percentile levels of soil PMN were selected to further study the effects of POM on soil N mineralization by quantifying the net N mineralization in original soils and soils from which POM was removed. Both soil POM carbon (POM-C and N (POM-N contents were 45.8% and 55.8% higher under the RR rotation compared to the CR rotation, respectively. The PMN contents were highly correlated with the POM contents. The PMN and microbial biomass N (MBN contents concurrently and significantly decreased when POM was removed. The reduction rate of PMN was positively correlated with changes in MBN after the removal of POM. The reduction rates of PMN and MBN after POM removal are lower under RR rotations (38.0% and 16.3%, respectively than CR rotations (45.6% and 19.5%, respectively. Furthermore, infrared spectroscopy indicated that compounds with low-bioavailability accumulated (e.g., aromatic recalcitrant materials in the soil POM fraction under the RR rotation but not under the CR rotation. The results of the present study demonstrated that POM plays a vital role in soil N mineralization under different rotation systems. The discrepancy between POM content and composition resulting from different crop rotation systems caused differences in N mineralization in soils.

  3. Composition of organic matter in earthworm casts depending on litter quality

    Science.gov (United States)

    Ellerbrock, R. H.; Gerke, H. H.; Schrader, S.; Leue, M.

    2009-04-01

    Earthworms contribute to decomposition and stabilization of organic matter (OM) in soil. The digestion during intestinal passage inside worms may lead to a change in the composition of OM. It is largely unknown if and how the type of litter the earthworm is feeding on is affecting the OM composition in the casts. Fourier Transform infrared spectroscopy (FTIR) is used to determine the hydrophobic CH- (A) and the hydrophilic CO- (B) functional groups in OM. The objective was to compare the A/B- ratios of litter samples with that of (i) the corresponding casts of the primary decomposer Lumbricus terrestris and (ii) the water contact angles of ground cast samples and at intact cast surfaces. Litter from 10 different plant species including leaves of birch, beech, oak, spruce, pear, mustard and wheat straw (3 replicates) was offered separately to L. terrestris in microcosms containing a Luvisol soil. The OM composition of litter and that of casts, collected from the soil surface after 4-weeks was analyzed with FTIR (DRIFT technique). The A/B ratio of casts was generally increased as compared to that of the soil. For most litter types, the A/B ratio of cast was relatively similar except for casts from birch (Betula pendula) and pear (Pyrus communis) where the OM show a 3-times higher A/B ratio as compared to wheat (Triticum aestivum) or beech (Fagus sylvatica) casts. The higher A/B ratios seem to be related to the relative higher C/N ratios in the casts from Betula pendula and Pyrus communis feeding experiments. The results indicate that digestion of litter by the worm may change OM composition. The assumption that earthworm casts may enrich hydrophobic OM components could be verified only partly. However particulate and soluble OM fractions in the earthworm casts could have contributed to such differentiation.

  4. Denitrification potential and its relation to organic carbon quality in three coastal wetland soils

    Energy Technology Data Exchange (ETDEWEB)

    Dodla, Syam K. [School of Plant, Environmental and Soil Sciences, Louisiana State Univ. Agricultural Center, Baton Rouge, LA 70803 (United States); Wang, Jim J. [School of Plant, Environmental and Soil Sciences, Louisiana State Univ. Agricultural Center, Baton Rouge, LA 70803 (United States)], E-mail: jjwang@agctr.lsu.edu; DeLaune, Ron D. [Wetland Biogeochemistry Institute, School of the Coast and Environment, Louisiana State University, Baton Rouge, LA 70803 (United States); Cook, Robert L. [Chemistry Department, Louisiana State University, Baton Rouge, LA 70803 (United States)

    2008-12-15

    Capacity of a wetland to remove nitrate through denitrification is controlled by its physico-chemical and biological characteristics. Understanding these characteristics will help better to guide beneficial use of wetlands in processing nitrate. This study was conducted to determine the relationship between soil organic carbon (SOC) quality and denitrification rate in Louisiana coastal wetlands. Composite soil samples of different depths were collected from three different wetlands along a salinity gradient, namely, bottomland forest swamp (FS), freshwater marsh (FM), and saline marsh (SM) located in the Barataria Basin estuary. Potential denitrification rate (PDR) was measured by acetylene inhibition method and distribution of carbon (C) moieties in organic C was determined by {sup 13}C solid-state NMR. Of the three wetlands, the FM soil profile exhibited the highest PDR on both unit weight and unit volume basis as compared to FS and SM. The FM also tended to yield higher amount of N{sub 2}O as compared to the FS and SM especially at earlier stages of denitrification, suggesting incomplete reduction of NO{sub 3}{sup -} at FM and potential for emission of N{sub 2}O. Saline marsh soil profile had the lowest PDR on the unit volume basis. Increasing incubation concentration from 2 to 10 mg NO{sub 3}{sup -}-N L{sup -1} increased PDR by 2 to 6 fold with the highest increase in the top horizons of FS and SM soils. Regression analysis showed that across these three wetland systems, organic C has significant effect in regulating PDR. Of the compositional C moieties, polysaccharides positively influenced denitrification rate whereas phenolics (likely phenolic adehydes and ketonics) negatively affected denitrification rate in these wetland soils. These results could have significant implication in integrated assessment and management of wetlands for treating nutrient-rich biosolids and wastewaters, non-point source agricultural runoff, and nitrate found in the diverted

  5. Biogenic volatile organic compound emissions along a high arctic soil moisture gradient.

    Science.gov (United States)

    Svendsen, Sarah Hagel; Lindwall, Frida; Michelsen, Anders; Rinnan, Riikka

    2016-12-15

    Emissions of biogenic volatile organic compounds (BVOCs) from terrestrial ecosystems are important for the atmospheric chemistry and the formation of secondary organic aerosols, and may therefore influence the climate. Global warming is predicted to change patterns in precipitation and plant species compositions, especially in arctic regions where the temperature increase will be most pronounced. These changes are potentially highly important for the BVOC emissions but studies investigating the effects are lacking. The aim of this study was to investigate the quality and quantity of BVOC emissions from a high arctic soil moisture gradient extending from dry tundra to a wet fen. Ecosystem BVOC emissions were sampled five times in the July-August period using a push-pull enclosure technique, and BVOCs trapped in absorbent cartridges were analyzed using gas chromatography-mass spectrometry. Plant species compositions were estimated using the point intercept method. In order to take into account important underlying ecosystem processes, gross ecosystem production, ecosystem respiration and net ecosystem production were measured in connection with chamber-based BVOC measurements. Highest emissions of BVOCs were found from vegetation communities dominated by Salix arctica and Cassiope tetragona, which had emission profiles dominated by isoprene and monoterpenes, respectively. These results show that emissions of BVOCs are highly dependent on the plant cover supported by the varying soil moisture, suggesting that high arctic BVOC emissions may affect the climate differently if soil water content and plant cover change. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Assessing the stability of soil organic matter by fractionation and 13C isotope techniques

    Science.gov (United States)

    Larionova, A. A.; Zolotareva, B. N.; Kvitkina, A. K.; Evdokimov, I. V.; Bykhovets, S. S.; Stulin, A. F.; Kuzyakov, Ya. V.; Kudeyarov, V. N.

    2015-02-01

    Carbon pools of different stabilities have been separated from the soil organic matter of agrochernozem and agrogray soil samples. The work has been based on the studies of the natural abundance of the carbon isotope composition by C3-C4 transition using the biokinetic, size-density, and chemical fractionation (6 M HCl hydrolysis) methods. The most stable pools with the minimum content of new carbon have been identified by particle-size and chemical fractionation. The content of carbon in the fine fractions has been found to be close to that in the nonhydrolyzable residue. This pool makes up 65 and 48% of Corg in the agrochernozems and agrogray soils, respectively. The combination of the biokinetic approach with particle-size fractionation or 6 M HCl hydrolysis has allowed assessing the size of the medium-stable organic carbon pool with a turnover time of several years to several decades. The organic matter pool with this turnover rate is usually identified from the variation in the 13C abundance by C3-C4 transition. In the agrochernozems and agrogray soils, the medium-stable carbon pool makes up 35 and 46% of Corg, respectively. The isotope indication may be replaced by a nonisotope method to significantly expand the study of the inert and mediumstable organic matter pools in the geographical aspect, but this requires a comparative analysis of particle-size and chemical fractionation data for all Russian soils.

  7. Cycling downwards - dissolved organic matter in soils

    NARCIS (Netherlands)

    Kaiser, K.; Kalbitz, K.

    2012-01-01

    Dissolved organic matter has been recognized as mobile, thus crucial to translocation of metals, pollutants but also of nutrients in soil. We present a conceptual model of the vertical movement of dissolved organic matter with soil water, which deviates from the view of a chromatographic stripping

  8. Methods of soil organic carbon determination in Brazilian savannah soils

    Directory of Open Access Journals (Sweden)

    Juliana Hiromi Sato

    2014-08-01

    Full Text Available Several methods exist for determining soil organic carbon, and each one has its own advantages and limitations. Consequently, a comparison of the experimental results obtained when these methods are employed is hampered, causing problems in the comparison of carbon stocks in soils. This study aimed at evaluating the analytical procedures used in the determination of carbon and their relationships with soil mineralogy and texture. Wet combustion methods, including Walkley-Black, Mebius and Colorimetric determination as well as dry combustion methods, such as Elemental and Gravimetric Analysis were used. Quantitative textural and mineralogical (kaolinite, goethite and gibbsite analyses were also carried out. The wet digestion methods underestimated the concentration of organic carbon, while the gravimetric method overestimated. Soil mineralogy interfered with the determination of carbon, with emphasis on the gravimetric method that was greatly influenced by gibbsite.

  9. Organic contaminants in soil : desorption kinetics and microbial degradation

    NARCIS (Netherlands)

    Schlebaum, W.

    1999-01-01

    The availability of organic contaminants in soils or sediments for microbial degradation or removal by physical means (e.g.) soil washing or soil venting) depends on the desorption kinetics of these contaminants from the soil matrix. When the organic contaminants desorb very slow from the

  10. Clay-associated organic matter in kaolinitic and smectitic soils

    NARCIS (Netherlands)

    Wattel-Koekkoek, E.J.W.

    2002-01-01

    The primary source of soil organic matter is plant debris of all kinds, such as dead roots, leaves and branches that enter into the soil and are then biologically decomposed at variable rates. Organic matter has many different important functions on a local and global scale. Soil organic matter is

  11. Soil salinity decreases global soil organic carbon stocks.

    Science.gov (United States)

    Setia, Raj; Gottschalk, Pia; Smith, Pete; Marschner, Petra; Baldock, Jeff; Setia, Deepika; Smith, Jo

    2013-11-01

    Saline soils cover 3.1% (397 million hectare) of the total land area of the world. The stock of soil organic carbon (SOC) reflects the balance between carbon (C) inputs from plants, and losses through decomposition, leaching and erosion. Soil salinity decreases plant productivity and hence C inputs to the soil, but also microbial activity and therefore SOC decomposition rates. Using a modified Rothamsted Carbon model (RothC) with a newly introduced salinity decomposition rate modifier and a plant input modifier we estimate that, historically, world soils that are currently saline have lost an average of 3.47 tSOC ha(-1) since they became saline. With the extent of saline soils predicted to increase in the future, our modelling suggests that world soils may lose 6.8 Pg SOC due to salinity by the year 2100. Our findings suggest that current models overestimate future global SOC stocks and underestimate net CO2 emissions from the soil-plant system by not taking salinity effects into account. From the perspective of enhancing soil C stocks, however, given the lower SOC decomposition rate in saline soils, salt tolerant plants could be used to sequester C in salt-affected areas. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Proposal and Research Direction of Soil Mass Organic Reorganization

    Science.gov (United States)

    Zhang, Lu; Han, Jichang

    2018-01-01

    Land engineering as a new discipline has been temporarily outrageous. The proposition of soil body organic reorganization undoubtedly enriches the research content for the construction of land engineering disciplines. Soil body organic reconstruction is designed to study how to realize the ecological ecology of the land by studying the external force of nature, to study the influence of sunlight, wind and water on soil body, how to improve the soil physical structure, to further strengthen the research of biological enzymes and microbes, and promote the release and utilization of beneficial inert elements in soil body. The emerging of frontier scientific research issues with soil body organic reorganization to indicate directions for the future development of soil engineering.

  13. Selective Leaching of Dissolved Organic Matter From Alpine Permafrost Soils on the Qinghai-Tibetan Plateau

    Science.gov (United States)

    Wang, Yinghui; Xu, Yunping; Spencer, Robert G. M.; Zito, Phoebe; Kellerman, Anne; Podgorski, David; Xiao, Wenjie; Wei, Dandan; Rashid, Harunur; Yang, Yuanhe

    2018-03-01

    Ongoing global temperature rise has caused significant thaw and degradation of permafrost soils on the Qinghai-Tibetan Plateau (QTP). Leaching of organic matter from permafrost soils to aquatic systems is highly complex and difficult to reproduce in a laboratory setting. We collected samples from natural seeps of active and permafrost layers in an alpine swamp meadow on the QTP to shed light on the composition of mobilized dissolved organic matter (DOM) by combining optical measurements, ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry, radiocarbon (14C), and solid-state 13C nuclear magnetic resonance spectroscopy. Our results show that even though the active layer soils contain large amounts of proteins and carbohydrates, there is a selective release of aromatic components, whereas in the deep permafrost layer, carbohydrate and protein components are preferentially leached during the thawing process. Given these different chemical characteristics of mobilized DOM, we hypothesize that photomineralization contributes significantly to the loss of DOM that is leached from the seasonally thawed surface layer. However, with continued warming, biodegradation will become more important since biolabile materials such as protein and carbohydrate are preferentially released from deep-layer permafrost soils. This transition in DOM leachate source and associated chemical composition has ramifications for downstream fluvial networks on the QTP particularly in terms of processing of carbon and associated fluxes.

  14. Ecology and Evolution of Soil Nematode Chemotaxis

    NARCIS (Netherlands)

    Rasmann, S.; Ali, J.G.; Helder, J.; Putten, van der W.H.

    2012-01-01

    Plants influence the behavior of and modify community composition of soil-dwelling organisms through the exudation of organic molecules. Given the chemical complexity of the soil matrix, soil-dwelling organisms have evolved the ability to detect and respond to these cues for successful foraging. A

  15. Experimental increase in availability of a PAH complex organic contamination from an aged contaminated soil: Consequences on biodegradation

    International Nuclear Information System (INIS)

    Cébron, Aurélie; Faure, Pierre; Lorgeoux, Catherine; Ouvrard, Stéphanie; Leyval, Corinne

    2013-01-01

    Although high PAH content and detection of PAH-degraders, the PAH biodegradation is limited in aged-contaminated soils due to low PAH availability (i.e., 1%). Here, we tried to experimentally increase the soil PAH availability by keeping both soil properties and contamination composition. Organic extract was first removed and then re-incorporated in the raw soil as fresh contaminants. Though drastic, this procedure only allowed a 6-time increase in the PAH availability suggesting that the organic constituents more than ageing were responsible for low availability. In the re-contaminated soil, the mineralization rate was twice more important, the proportion of 5–6 cycles PAH was higher indicating a preferential degradation of lower molecular weight PAH. The extraction treatment induced bacterial and fungal community structures modifications, Pseudomonas and Fusarium solani species were favoured, and the relative quantity of fungi increased. In re-contaminated soil the percentage of PAH-dioxygenase gene increased, with 10 times more Gram negative representatives. -- Highlights: ► Re-incorporation of soil organic extract increased 6-times the PAH availability. ► Complexity of organic contamination is the main driver of PAH availability. ► Biodegradation of PAH with less than 5-cycles increased with increasing PAH availability. ► Pseudomonas and Fusarium species are favoured when PAH availability increased. -- More than ageing, the complexity of organic contamination is the main driver of PAH availability

  16. EFFECT OF IRRIGATION INTERVAL AND SOIL AMENDMENTS ON SOIL ORGANIC C, NITROGEN AND POTASSIUM OF SANDY SOIL AND GROWTH OF Jatropha curcas L.

    Directory of Open Access Journals (Sweden)

    Djajadi

    2013-06-01

    Full Text Available Inherently, sandy soil is the unfertile soil with low in all aspects of soil fertility and has a low capacity to retain water applied nutrients. To improve the fertility of sandy soil as media growth of Jatropha curcas, clay and organic matter may have important role when they are incorporated to the sandy soil. This study investigated the effect of irrigation interval and incorporation of clay together with organic matter to sandy soil on soil organic C, N, and K and growth of J. curcas. The rates of clay and organic matter incorporated to top sandy soil were 5% clay + 0.8% organic matter and 10% clay + 1.6% organic matter. Two irrigation intervals tested were 10 day and 20 day. The results found that incorporation of 10% clay + 1.6% organic matter to sandy soil increased soil C organic, N total and exchangeable K which in turn increased number of leaves and number of lateral branches of J curcas. Irrigation intervals had no effect on all parameters observed.

  17. Can differences in soil community composition after peat meadow restoration lead to different decomposition and mineralization rates?

    NARCIS (Netherlands)

    Dijk, van J.; Didden, W.A.M.; Kuenen, F.; Bodegom, van P.M.; Verhoef, H.A.; Aerts, R.

    2009-01-01

    Reducing decomposition and mineralization of organic matter by increasing groundwater levels is a common approach to reduce plant nutrient availability in many peat meadow restoration projects. The soil community is the main driver of these processes, but how community composition is affected by

  18. Soil organic matter status in forest soils - possible indicators for climate change induced site shifts

    Science.gov (United States)

    Koch, Nadine; Thiele-Bruhn, Sören

    2010-05-01

    The quantity and quality of soil organic matter (SOM) and SOM pools and thus the soil properties related to carbon sequestration and water retention are not constant but exhibit considerable variation through changing climate. In total changes in soil fertility and an increase in plant stress are expected. This is relevant for northwest Europe as well and may have economic and social impacts since functions of forests for wood production, groundwater recharge, soil protection and recreation might be affected. The study is done by comparative investigation of selected sites at four watersheds that represent typical forest stands in the region of Luxembourg and South West Germany. The aim is to identify SOM storage and stability in forest soils and its dependence on site properties and interaction with tree stand conditions. According to state of the art fractionation schemes functional C pools in forest soils and their stabilization mechanisms are investigated. In particular, distribution patterns are determined depending on location, tree stand and climatic conditions. Aim is to identify characteristics of SOM stability through fractionation of SOM according to density, particle size and chemical extractability and their subsequent analytical characterization. So far, reasons about the origin, composition and stabilization mechanisms underlying the different SOM pools are not fully understood. Presented are different patterns of distribution of SOM in relation to land use and site conditions, as well as similarities and differences between the different forest soils and results in addition to passive OM pool, which is mainly responsible for long-term stabilization of carbon in soils. These are aligned with selected general' soil properties such as pH, CEC and texture.

  19. Spectral Assessment of Soil Properties: Standoff Quantification of Soil Organic Matter Content in Surface Mineral Soils and Alaskan Peat

    Science.gov (United States)

    2017-08-01

    Soil Properties Standoff Quantification of Soil Organic Matter Content in Surface Mineral Soils and Alaskan Peat En gi ne er R es ea rc h an d D...ERDC 6.2 GRE ARTEMIS STO-R DRTSPORE ERDC TR-17-9 August 2017 Spectral Assessment of Soil Properties Standoff Quantification of Soil Organic...Matter Content in Surface Mineral Soils and Alaskan Peat Stacey L. Jarvis, Karen L. Foley, Robert M. Jones, Stephen D. Newman, and Robyn A. Barbato

  20. [Soil Microbial Respiration Under Different Soil Temperature Conditions and Its Relationship to Soil Dissolved Organic Carbon and Invertase].

    Science.gov (United States)

    Wu, Jing; Chen, Shu-tao; Hu, Zheng-hua; Zhang, Xu

    2015-04-01

    In order to investigate the soil microbial respiration under different temperature conditions and its relationship to soil dissolved organic carbon ( DOC) and invertase, an indoor incubation experiment was performed. The soil samples used for the experiment were taken from Laoshan, Zijinshan, and Baohuashan. The responses of soil microbial respiration to the increasing temperature were studied. The soil DOC content and invertase activity were also measured at the end of incubation. Results showed that relationships between cumulative microbial respiration of different soils and soil temperature could be explained by exponential functions, which had P values lower than 0.001. The coefficient of temperature sensitivity (Q10 value) varied from 1.762 to 1.895. The Q10 value of cumulative microbial respiration decreased with the increase of soil temperature for all soils. The Q10 value of microbial respiration on 27 days after incubation was close to that of 1 day after incubation, indicating that the temperature sensitivity of recalcitrant organic carbon may be similar to that of labile organic carbon. For all soils, a highly significant ( P = 0.003 ) linear relationship between cumulative soil microbial respiration and soil DOC content could be observed. Soil DOC content could explain 31.6% variances of cumulative soil microbial respiration. For the individual soil and all soils, the relationship between cumulative soil microbial respiration and invertase activity could be explained by a highly significant (P soil microbial respiration.

  1. Soil organic matter dynamics and the global carbon cycle

    International Nuclear Information System (INIS)

    Post, W.M.; Emanuel, W.R.; King, A.W.

    1992-01-01

    The large size and potentially long residence time of the soil organic matter pool make it an important component of the global carbon cycle. Net terrestrial primary production of about 60 Pg C·yr -1 is, over a several-year period of time, balanced by an equivalent flux of litter production and subsequent decomposition of detritus and soil organic matter. We will review many of the major factors that influence soil organic matter dynamics that need to be explicitly considered in development of global estimates of carbon turnover in the world's soils. We will also discuss current decomposition models that are general enough to be used to develop a representation of global soil organic matter dynamics

  2. Age heterogeneity of soil organic matter

    International Nuclear Information System (INIS)

    Rethemeyer, J.; Grootes, P.M.; Bruhn, F.; Andersen, N.; Nadeau, M.J.; Kramer, C.; Gleixner, G.

    2004-01-01

    Accelerator mass spectrometry (AMS) radiocarbon measurements were used to investigate the heterogeneity of organic matter in soils of agricultural long-term trial sites in Germany and Great Britain. The strong age heterogeneity of the soil organic matter (SOM) is reflected by highly variable 14 C values of different organic components, ranging from modern (>100 pMC) to 7% modern carbon (pMC). At the field experiment in Halle (Germany), located in a heavily industrialized area, an increase of 14 C content with increasing depth was observed even though the input of modern plant debris should be highest in the topsoil. This is attributed to a significant contribution of old carbon (of up to 50% in the topsoil) to SOM. As a test to exclude the old carbon contamination, more specific SOM fractions were extracted. However, even a phospholipid fraction representing viable microbial biomass that is supposed to be short-lived in SOM, shows a strong influence of old, refractory carbon, when radiocarbon dated. In contrast, 14 C data of other field trials distant from industrial areas indicate that there inputs of old carbon to the soil are lower or even absent. Such locations are more favorable to study SOM stabilization and to quantify turnover of organic carbon in soils

  3. The potential impact on the biodegradation of organic pollutants from composting technology for soil remediation.

    Science.gov (United States)

    Ren, Xiaoya; Zeng, Guangming; Tang, Lin; Wang, Jingjing; Wan, Jia; Wang, Jiajia; Deng, Yaocheng; Liu, Yani; Peng, Bo

    2018-02-01

    Large numbers of organic pollutants (OPs), such as polycyclic aromatic hydrocarbons, pesticides and petroleum, are discharged into soil, posing a huge threat to natural environment. Traditional chemical and physical remediation technologies are either incompetent or expensive, and may cause secondary pollution. The technology of soil composting or use of compost as soil amendment can utilize quantities of active microbes to degrade OPs with the help of available nutrients in the compost matrix. It is highly cost-effective for soil remediation. On the one hand, compost incorporated into contaminated soil is capable of increasing the organic matter content, which improves the soil environment and stimulates the metabolically activity of microbial community. On the other hand, the organic matter in composts would increase the adsorption of OPs and affect their bioavailability, leading to decreased fraction available for microorganism-mediated degradation. Some advanced instrumental analytical approaches developed in recent years may be adopted to expound this process. Therefore, the study on bioavailability of OPs in soil is extremely important for the application of composting technology. This work will discuss the changes of physical and chemical properties of contaminated soils and the bioavailability of OPs by the adsorption of composting matrix. The characteristics of OPs, types and compositions of compost amendments, soil/compost ratio and compost distribution influence the bioavailability of OPs. In addition, the impact of composting factors (composting temperature, co-substrates and exogenous microorganisms) on the removal and bioavailability of OPs is also studied. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. The soil organic carbon content of anthropogenically altered organic soils effects the dissolved organic matter quality, but not the dissolved organic carbon concentrations

    Science.gov (United States)

    Frank, Stefan; Tiemeyer, Bärbel; Bechtold, Michel; Lücke, Andreas; Bol, Roland

    2016-04-01

    Dissolved organic carbon (DOC) is an important link between terrestrial and aquatic ecosystems. This is especially true for peatlands which usually show high concentrations of DOC due to the high stocks of soil organic carbon (SOC). Most previous studies found that DOC concentrations in the soil solution depend on the SOC content. Thus, one would expect low DOC concentrations in peatlands which have anthropogenically been altered by mixing with sand. Here, we want to show the effect of SOC and groundwater level on the quantity and quality of the dissolved organic matter (DOM). Three sampling sites were installed in a strongly disturbed bog. Two sites differ in SOC (Site A: 48%, Site B: 9%) but show the same mean annual groundwater level of 15 and 18 cm below ground, respectively. The SOC content of site C (11%) is similar to Site B, but the groundwater level is much lower (-31 cm) than at the other two sites. All sites have a similar depth of the organic horizon (30 cm) and the same land-use (low-intensity sheep grazing). Over two years, the soil solution was sampled bi-weekly in three depths (15, 30 and 60 cm) and three replicates. All samples were analyzed for DOC and selected samples for dissolved organic nitrogen (DON) and delta-13C and delta-15N. Despite differences in SOC and groundwater level, DOC concentrations did not differ significantly (A: 192 ± 62 mg/L, B: 163 ± 55 mg/L and C: 191 ± 97 mg/L). At all sites, DOC concentrations exceed typical values for peatlands by far and emphasize the relevance even of strongly disturbed organic soils for DOC losses. Individual DOC concentrations were controlled by the temperature and the groundwater level over the preceding weeks. Differences in DOM quality were clearer. At site B with a low SOC content, the DOC:DON ratio of the soil solution equals the soil's C:N ratio, but the DOC:DON ratio is much higher than the C:N ratio at site A. In all cases, the DOC:DON ratio strongly correlates with delta-13C. There is no

  5. Mapping Soil Organic Matter with Hyperspectral Imaging

    Science.gov (United States)

    Moni, Christophe; Burud, Ingunn; Flø, Andreas; Rasse, Daniel

    2014-05-01

    Soil organic matter (SOM) plays a central role for both food security and the global environment. Soil organic matter is the 'glue' that binds soil particles together, leading to positive effects on soil water and nutrient availability for plant growth and helping to counteract the effects of erosion, runoff, compaction and crusting. Hyperspectral measurements of samples of soil profiles have been conducted with the aim of mapping soil organic matter on a macroscopic scale (millimeters and centimeters). Two soil profiles have been selected from the same experimental site, one from a plot amended with biochar and another one from a control plot, with the specific objective to quantify and map the distribution of biochar in the amended profile. The soil profiles were of size (30 x 10 x 10) cm3 and were scanned with two pushbroomtype hyperspectral cameras, one which is sensitive in the visible wavelength region (400 - 1000 nm) and one in the near infrared region (1000 - 2500 nm). The images from the two detectors were merged together into one full dataset covering the whole wavelength region. Layers of 15 mm were removed from the 10 cm high sample such that a total of 7 hyperspectral images were obtained from the samples. Each layer was analyzed with multivariate statistical techniques in order to map the different components in the soil profile. Moreover, a 3-dimensional visalization of the components through the depth of the sample was also obtained by combining the hyperspectral images from all the layers. Mid-infrared spectroscopy of selected samples of the measured soil profiles was conducted in order to correlate the chemical constituents with the hyperspectral results. The results show that hyperspectral imaging is a fast, non-destructive technique, well suited to characterize soil profiles on a macroscopic scale and hence to map elements and different organic matter quality present in a complete pedon. As such, we were able to map and quantify biochar in our

  6. Assessing soil constituents and labile soil organic carbon by mid-infrared photoacoustic spectroscopy

    DEFF Research Database (Denmark)

    Peltre, Clément; Bruun, Sander; Du, Changwen

    2014-01-01

    ) degradability. The objective of this study was to assess the potential of FTIR-PAS for the characterisation of the labile fraction of SOC and more classical soil parameters, such as carbon and clay content, for a range of 36 soils collected from various field experiments in Denmark. Partial least squares (PLS...... signal. This also means that it should be advantageous for soil analysis because of its highly opaque nature. However, only a limited number of studies have so far applied FTIR-PAS to soil characterization and investigation is still required into its potential to determine soil organic carbon (SOC......) regression was used to correlate the collected FTIR-PAS spectra with the proportion of soil organic carbon mineralised after 238 days of incubation at 15°C and pF 2 (C238d) taken as an indicator of the labile fraction of SOC. Results showed that it is possible to predict total organic carbon content, total...

  7. Stabilization of organic matter in the raised-bed soils of tidal swamplands is influenced by the types and the amounts of organic matter application

    Directory of Open Access Journals (Sweden)

    A R Saidy

    2015-05-01

    Full Text Available Farmers in tidal swamplands annually added organic matter (OM onto the raised beds to maintain organic matter contents and thereby maintain soil productivity of the raised beds. This experiment aimed to study the influence of the types and the amounts of OM on the stabilization of organic matter in the raised-bed soils. Four types of OM: rice straw, eceng gondok (Eichornia crassipes, purun tikus  (Eleocharis dulcis and mixed  rice straw-eceng gondok were added to a 27-year raised bed soil with 4 different rates: 0, 0.5, 1.0 and 2.0  of maximum sorption capacity (Qmax, and the OM stabilization was quantified after 10 weeks of OM addition.  Results of this study showed with the exception of rice straw, OM addition to soil resulted in increases in the mineralization of soil OM thereby inducing priming effect. Addition of rice straw at rate of 0.5 of Qmax resulted in stabilization of 46% added OM, while only 30% and 37% of added OM was stabilized when OM was added to soils at rates of 1.0 and 2.0 Qmax, respectively.  This study showed that the stabilization of OM in raised bed soils were influenced by the chemical composition of OM and the amount of added OM.

  8. Stabilization of organic matter in the raised-bed soils of tidal swamplands is influenced by the types and the amounts of organic matter application

    Directory of Open Access Journals (Sweden)

    A R Saidy

    2015-03-01

    Full Text Available Farmers in tidal swamplands annually added organic matter (OM onto the raised beds to maintain organic matter contents and thereby maintain soil productivity of the raised beds. This experiment aimed to study the influence of the types and the amounts of OM on the stabilization of organic matter in the raised-bed soils. Four types of OM: rice straw, eceng gondok (Eichornia crassipes, purun tikus  (Eleocharis dulcis and mixed  rice straw-eceng gondok were added to a 27-year raised bed soil with 4 different rates: 0, 0.5, 1.0 and 2.0  of maximum sorption capacity (Qmax, and the OM stabilization was quantified after 10 weeks of OM addition.  Results of this study showed with the exception of rice straw, OM addition to soil resulted in increases in the mineralization of soil OM thereby inducing priming effect. Addition of rice straw at rate of 0.5 of Qmax resulted in stabilization of 46% added OM, while only 30% and 37% of added OM was stabilized when OM was added to soils at rates of 1.0 and 2.0 Qmax, respectively.  This study showed that the stabilization of OM in raised bed soils were influenced by the chemical composition of OM and the amount of added OM.

  9. Soil Organic Carbon dynamics in agricultural soils of Veneto Region

    Science.gov (United States)

    Bampa, F. B.; Morari, F. M.; Hiederer, R. H.; Toth, G. T.; Giandon, P. G.; Vinci, I. V.; Montanarella, L. M.; Nocita, M.

    2012-04-01

    One of the eight soil threats expressed in the European Commission's Thematic Strategy for Soil Protection (COM (2006)231 final) it's the decline in Soil Organic Matter (SOM). His preservation is recognized as with the objective to ensure that the soils of Europe remain healthy and capable of supporting human activities and ecosystems. One of the key goals of the strategy is to maintain and improve Soil Organic Carbon (SOC) levels. As climate change is identified as a common element in many of the soil threats, the European Commission (EC) intends to assess the actual contribution of the soil protection to climate change mitigation and the effects of climate change on the possible depletion of SOM. A substantial proportion of European land is occupied by agriculture, and consequently plays a crucial role in maintaining natural resources. Organic carbon preservation and sequestration in the EU's agricultural soils could have some potential to mitigate the effects of climate change, particularly linked to preventing certain land use changes and maintaining SOC stocks. The objective of this study is to assess the SOC dynamics in agricultural soils (cropland and grassland) at regional scale, focusing on changes due to land use. A sub-objective would be the evaluation of the most used land management practices and their effect on SOC content. This assessment aims to determine the geographical distribution of the potential GHG mitigation options, focusing on hot spots in the EU, where mitigation actions would be particularly efficient and is linked with the on-going work in the JRC SOIL Action. The pilot area is Veneto Region. The data available are coming from different sources, timing and involve different variables as: soil texture, climate, soil disturbance, managements and nutrients. The first source of data is the LUCAS project (Land Use/Land Cover Area Frame statistical Survey). Started in 2001, the LUCAS project aims to monitor changes in land cover/use and

  10. SOIL NITROGEN TRANSFORMATIONS AND ROLE OF LIGHT FRACTION ORGANIC MATTER IN FOREST SOILS

    Science.gov (United States)

    Depletion of soil organic matter through cultivation may alter substrate availability for microbes, altering the dynamic balance between nitrogen (N) immobilization and mineralization. Soil light fraction (LF) organic matter is an active pool that decreases upon cultivation, and...

  11. Studying soil organic carbon in Mediterranean soils. Different techniques and the effects of land management and use, climatic and topographic conditions, organic waste addition

    Science.gov (United States)

    Lozano-García, Beatriz; Parras-Alcántara, Luis

    2014-05-01

    Soil organic carbon (SOC) is an important component of global carbon cycle, and the changes of its accumulation and decomposition directly affect terrestrial ecosystem carbon storage and global carbon balance. The ability of soil to store SOC depends to a great extent on climate and some soil properties, in addition to the cultivation system in agricultural soils. Soils in Mediterranean areas are very poor in organic matter and are exposed to progressive degradation processes. Therefore, a lot of actions are conducted to improve soil quality and hence mitigate the negative environmental and agronomic limitations of these soils. Improved cultivation systems (conversion of cropland to pastoral and forest lands, conventional tillage to conservation tillage, no manure use to regular addition of manure) have been introduced in recent years, increasing the contents in SOC and therefore, enhancing the soil quality, reducing soil erosion and degradation, improving surface water quality and increasing soil productivity. Moreover, the organic waste addition to the soils is especially useful in Mediterranean regions, where the return of organic matter to soil not only does it help soils store SOC and improve soil structure and soil fertility but also it allows to reuse a wide range of agro-industrial wastes.

  12. Greenhouse gas fluxes from agricultural soils under organic and non-organic management — A global meta-analysis

    International Nuclear Information System (INIS)

    Skinner, Colin; Gattinger, Andreas; Muller, Adrian; Mäder, Paul; Fließbach, Andreas; Stolze, Matthias; Ruser, Reiner; Niggli, Urs

    2014-01-01

    It is anticipated that organic farming systems provide benefits concerning soil conservation and climate protection. A literature search on measured soil-derived greenhouse gas (GHG) (nitrous oxide and methane) fluxes under organic and non-organic management from farming system comparisons was conducted and followed by a meta-analysis. Up to date only 19 studies based on field measurements could be retrieved. Based on 12 studies that cover annual measurements, it appeared with a high significance that area-scaled nitrous oxide emissions from organically managed soils are 492 ± 160 kg CO 2 eq. ha −1 a −1 lower than from non-organically managed soils. For arable soils the difference amounts to 497 ± 162 kg CO 2 eq. ha −1 a −1 . However, yield-scaled nitrous oxide emissions are higher by 41 ± 34 kg CO 2 eq. t −1 DM under organic management (arable and use). To equalize this mean difference in yield-scaled nitrous oxide emissions between both farming systems, the yield gap has to be less than 17%. Emissions from conventionally managed soils seemed to be influenced mainly by total N inputs, whereas for organically managed soils other variables such as soil characteristics seemed to be more important. This can be explained by the higher bioavailability of the synthetic N fertilisers in non-organic farming systems while the necessary mineralisation of the N sources under organic management leads to lower and retarded availability. Furthermore, a higher methane uptake of 3.2 ± 2.5 kg CO 2 eq. ha −1 a −1 for arable soils under organic management can be observed. Only one comparative study on rice paddies has been published up to date. All 19 retrieved studies were conducted in the Northern hemisphere under temperate climate. Further GHG flux measurements in farming system comparisons are required to confirm the results and close the existing knowledge gaps. - Highlights: • Lower area-scaled nitrous oxide emissions from soils managed organically compared

  13. Invasive soil organisms and their effects on belowground processes

    Science.gov (United States)

    Erik Lilleskov; Jr. Mac A. Callaham; Richard Pouyat; Jane E. Smith; Michael Castellano; Grizelle Gonzalez; D. Jean Lodge; Rachel Arango; Frederick. Green

    2010-01-01

    Invasive species have a wide range of effects on soils and their inhabitants. By altering soils, through their direct effects on native soil organisms (including plants), and by their interaction with the aboveground environment, invasive soil organisms can have dramatic effects on the environment, the economy and human health. The most widely recognized effects...

  14. Soil-soil solution distribution coefficient of soil organic matter is a key factor for that of radioiodide in surface and subsurface soils.

    Science.gov (United States)

    Unno, Yusuke; Tsukada, Hirofumi; Takeda, Akira; Takaku, Yuichi; Hisamatsu, Shun'ichi

    2017-04-01

    We investigated the vertical distribution of the soil-soil-solution distribution coefficients (K d ) of 125 I, 137 Cs, and 85 Sr in organic-rich surface soil and organic-poor subsurface soil of a pasture and an urban forest near a spent-nuclear-fuel reprocessing plant in Rokkasho, Japan. K d of 137 Cs was highly correlated with water-extractable K + . K d of 85 Sr was highly correlated with water-extractable Ca 2+ and SOC. K d of 125 I - was low in organic-rich surface soil, high slightly below the surface, and lowest in the deepest soil. This kinked distribution pattern differed from the gradual decrease of the other radionuclides. The thickness of the high- 125 I - K d middle layer (i.e., with high radioiodide retention ability) differed between sites. K d of 125 I - was significantly correlated with K d of soil organic carbon. Our results also showed that the layer thickness is controlled by the ratio of K d -OC between surface and subsurface soils. This finding suggests that the addition of SOC might prevent further radioiodide migration down the soil profile. As far as we know, this is the first report to show a strong correlation of a soil characteristic with K d of 125 I - . Further study is needed to clarify how radioiodide is retained and migrates in soil. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Preparation of Sandy Soil Stabilizer for Roads Based on Radiation Modified Polymer Composite

    International Nuclear Information System (INIS)

    Elnahas, H.H.

    2016-01-01

    Radiation modified polymer composite (RMPC) was studied to build an extremely durable sandy road, construct a trail or bath, or control dust and erosion. A dilute solution of composite binds sandy soil fines through a coagulation bonding process. The result is a dense soil structure that has superior resistance to cracks and water penetration and can also solve erosion control problems. In erosion control applications, diluted composite is merely sprayed into sandy soil without compaction, effectively sealing the surface to prevent air-born dust or deterioration from erosion. The prepared composite has an elastic and melt-able film formation that imparts thermal compacting to the stabilized sandy soil after full dryness for sandy road leveling, repairing and restoration processes. The prepared composite is environmentally economical when compared with traditional sandy soil stabilizing (SSS) or sealing methods.

  16. Soil nitrogen mineralisation and organic matter composition revealed by 13C NMR spectroscopy under repeated prescribed burning in eucalypt forests of south-east Queensland

    International Nuclear Information System (INIS)

    Guinto, D. F.; Saffigna, P. G.; Xu, Z. H.; House, A. P. N.; Perera, M. C. S.

    1999-01-01

    The effects of burning on in situ extractable nitrogen (NH + 4 -N+NO - 3 -N) and net N mineralisation following scheduled fuel reduction burns in repeatedly burnt dry and wet sclerophyll forest sites in south-east Queensland were assessed. In addition, soil organic matter composition in the wet sclerophyll site was assessed by 13 C NMR spectroscopy. The results showed that at the dry sclerophyll site, extractable N and net N mineralisation for 1 year were largely unaffected by burning, while at the wet sclerophyll site, these parameters decreased. 13 C NMR analysis of soil samples from the wet sclerophyll site revealed that there was a significant reduction in the proportion of O-alkyl (alkoxy/carbohydrate) C with increasing burning frequency. Statistically significant effects on the other chemical shift regions were not detected. The ratio of alkyl C to O-alkyl C, a proposed index of organic matter decomposition, increased with increasing burning frequency. A high ratio of alkyl C to O-alkyl C suggests low amounts of carbohydrates relative to waxes and cutins, which could in turn lead to slower mineralisation. The findings are in accord with this hypothesis. There were significant linear relationships between cumulative N mineralisation for 1 year and the proportions of alkyl C and O-alkyl C, and the ratio of alkyl C/O-alkyl C. Thus, in addition to reductions in substrate quantity (low organic C and total N for burnt soils), there was also an alteration of substrate quality as revealed by 13 C NMR spectroscopy which is reflected in low N mineralisation. Copyright (1999) CSIRO Publishing

  17. The evaluation of polycyclic aromatic hydrocarbons (PAHs) biodegradation kinetics in soil amended with organic fertilizers and bulking agents.

    Science.gov (United States)

    Włóka, Dariusz; Placek, Agnieszka; Rorat, Agnieszka; Smol, Marzena; Kacprzak, Małgorzata

    2017-11-01

    The aim of this study was to investigate the polycyclic aromatic hydrocarbons (PAHs) biodegradation kinetics in soils fertilized with organic amendments (sewage sludge, compost), bulking agents (mineral sorbent, silicon dioxide in form of nano powder), and novel compositions of those materials. The scope of conducted works includes a cyclic CO 2 production measurements and the determinations of PAHs content in soil samples, before and after 3-months of incubation. Obtained results show that the use of both type of organic fertilizers have a positive effect on the PAHs removal from soil. However, the CO 2 emission remains higher only in the first stage of the process. The best acquired means in terms of PAHs removal as well as most sustained CO 2 production were noted in samples treated with the mixtures of organic fertilizers and bulking agents. In conclusion the addition of structural forming materials to the organic fertilizers was critical for the soil bioremediation efficiency. Therefore, the practical implementation of collected data could find a wide range of applications during the design of new, more effective solutions for the soil bioremediation purposes. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Disturbance of Soil Organic Matter and Nitrogen Dynamics: Implications for Soil and Water Quality

    Science.gov (United States)

    2004-06-30

    Elliott, E.T., 1992. Particulate soil organic- matter changes across a grassland cultivation sequence. Soil Sci. Soc. Am. J. 56, 777–783. Dale, V.H...C.A., Elliott, E.T., 1992. Particulate soil organic-matter changes across a grassland cultivation sequence. Soil Science Society of America Journal...1645-1650. Van Straalen, N.M. 1997. How to measure no effect. 2. Threshold effects in ecotoxicology . Environmetrics 8: 249-253. Verburg, P.S.J

  19. Effects of Tillage Practices on Soil Organic Carbon and Soil Respiration

    Science.gov (United States)

    Rusu, Teodor; Ioana Moraru, Paula; Bogdan, Ileana; Ioan Pop, Adrian

    2016-04-01

    Soil tillage system and its intensity modify by direct and indirect action soil temperature, moisture, bulk density, porosity, penetration resistance and soil structural condition. Minimum tillage and no-tillage application reduce or completely eliminate the soil mobilization, due to this, soil is compacted in the first years of application. The degree of compaction is directly related to soil type and its state of degradation. All this physicochemical changes affect soil biology and soil respiration. Soil respiration leads to CO2 emissions from soil to the atmosphere, in significant amounts for the global carbon cycle. Soil respiration is one measure of biological activity and decomposition. Soil capacity to produce CO2 varies depending on soil, season, intensity and quality of agrotechnical tillage, soil water, cultivated plant and fertilizer. Our research follows the effects of the three tillage systems: conventional system, minimum tillage and no-tillage on soil respiration and finally on soil organic carbon on rotation soybean - wheat - maize, obtained on an Argic Faeoziom from the Somes Plateau, Romania. To quantify the change in soil respiration under different tillage practices, determinations were made for each crop in four vegetative stages (spring, 5-6 leaves, bean forming, harvest). Soil monitoring system of CO2 and O2 included gradient method, made by using a new generation of sensors capable of measuring CO2 concentration in-situ and quasi-instantaneous in gaseous phase. At surface soil respiration is made by using ACE Automated Soil CO2 Exchange System. These areas were was our research presents a medium multi annual temperature of 8.20C medium of multi annual rain drowns: 613 mm. The experimental variants chosen were: i). Conventional system: reversible plough (22-25 cm) + rotary grape (8-10 cm); ii). Minimum tillage system: paraplow (18-22 cm) + rotary grape (8-10 cm); iii). No-tillage. The experimental design was a split-plot design with three

  20. Effects of elevated atmospheric CO2 on soil organic carbon dynamics in a mediterranean forest ecosystem

    NARCIS (Netherlands)

    Gahrooee, F.R.

    1998-01-01

    Elevated atmospheric CO 2 has the potential to change the composition and dynamics of soil organic matter (SOM) and consequently C and N cycling in terrestrial ecosystems. Because of the long-lived nature of SOM, long-lasting experiments are required for studying the

  1. [Organic carbon and carbon mineralization characteristics in nature forestry soil].

    Science.gov (United States)

    Yang, Tian; Dai, Wei; An, Xiao-Juan; Pang, Huan; Zou, Jian-Mei; Zhang, Rui

    2014-03-01

    Through field investigation and indoor analysis, the organic carbon content and organic carbon mineralization characteristics of six kinds of natural forest soil were studied, including the pine forests, evergreen broad-leaved forest, deciduous broad-leaved forest, mixed needle leaf and Korean pine and Chinese pine forest. The results showed that the organic carbon content in the forest soil showed trends of gradual decrease with the increase of soil depth; Double exponential equation fitted well with the organic carbon mineralization process in natural forest soil, accurately reflecting the mineralization reaction characteristics of the natural forest soil. Natural forest soil in each layer had the same mineralization reaction trend, but different intensity. Among them, the reaction intensity in the 0-10 cm soil of the Korean pine forest was the highest, and the intensities of mineralization reaction in its lower layers were also significantly higher than those in the same layers of other natural forest soil; comparison of soil mineralization characteristics of the deciduous broad-leaved forest and coniferous and broad-leaved mixed forest found that the differences of litter species had a relatively strong impact on the active organic carbon content in soil, leading to different characteristics of mineralization reaction.

  2. Dynamics of soil organic carbon and microbial activity in treated wastewater irrigated agricultural soils along soil profiles

    Science.gov (United States)

    Jüschke, Elisabeth; Marschner, Bernd; Chen, Yona; Tarchitzky, Jorge

    2010-05-01

    Treated wastewater (TWW) is an important source for irrigation water in arid and semiarid regions and already serves as an important water source in Jordan, the Palestinian Territories and Israel. Reclaimed water still contains organic matter (OM) and various compounds that may effect microbial activity and soil quality (Feigin et al. 1991). Natural soil organic carbon (SOC) may be altered by interactions between these compounds and the soil microorganisms. This study evaluates the effects of TWW irrigation on the quality, dynamics and microbial transformations of natural SOC. Priming effects (PE) and SOC mineralization were determined to estimate the influence of TWW irrigation on SOC along soil profiles of agricultural soils in Israel and the Westbank. The used soil material derived from three different sampling sites allocated in Israel and The Palestinian Authority. Soil samples were taken always from TWW irrigated sites and control fields from 6 different depths (0-10, 10-20, 20-30, 30-50, 50-70, 70-100 cm). Soil carbon content and microbiological parameters (microbial biomass, microbial activities and enzyme activities) were investigated. In several sites, subsoils (50-160 cm) from TWW irrigated plots were depleted in soil organic matter with the largest differences occurring in sites with the longest TWW irrigation history. Laboratory incubation experiments with additions of 14C-labelled compounds to the soils showed that microbial activity in freshwater irrigated soils was much more stimulated by sugars or amino acids than in TWW irrigated soils. The lack of such "priming effects" (Hamer & Marschner 2005) in the TWW irrigated soils indicates that here the microorganisms are already operating at their optimal metabolic activity due to the continuous substrate inputs with soluble organic compounds from the TWW. The fact that PE are triggered continuously due to TWW irrigation may result in a decrease of SOC over long term irrigation. Already now this could be

  3. Wildfire Ash: Chemical Composition, Ash-Soil Interactions and Environmental Impacts

    Science.gov (United States)

    Brook, Anna; Hamzi, Seham; Wittenberg, Lea

    2015-04-01

    produced ash has significant and not always constructive pedological, ecological, hydrological and geomorphological effects and impacts (Shakesby, 2011). Abundant scientific information is assembled either from control fires by collecting samples before and after wildfire event, or conducting laboratory experiments exanimating data under truly isolated conditions (Lugassi et al., 2013). However, an integration and synthesis of the knowledge about ash including deeper understanding of inter-correlation between chemical, physical and morphological compounds in open post-burn environment and its possible interactions in soil formation or impact on soil composition are highly needed. The main aim of the presented study was to advance the science of soil-fire relationship by recognizing the remains ash as a new soil-forming factor, on par with the traditionally recognized factors: parent material, topography, time, climate, organisms, and recently recognized human activity as the sixth factor. This research was conducted to develop new methods to assess impacts and quantify the contributions/influences of post-fire products, mainly ash, on soil composition and soil properties in post-burned environment. We conducted several controlled experiments using 40 soil samples (typical Mediterranean Rendzina soil, pH 6.84, a grayish-brown, humus- and free calcium carbonate- rich, intra-zonal). The samples include bare soils and different types and loads of forest litter, were exposed to different temperatures (200° C, 400° C and 600° C) in a muffle furnace for 2 hours (Pereira et al. 2011) as fire temperature plays a key role in determining ash properties. The ash produced at a low temperatures (50% carbon and retains many of the structural characteristics of the parent material. At higher temperatures, the residue ash is greyish, consisted of very fine particles that preserve almost none of the original structural characteristics of the fuel (Woods and Balfour, 2008) creating

  4. [Thermodynamic forecasting of reagents composition for soils decontamination].

    Science.gov (United States)

    Nikolaev, V P; Nikolaevskiĭ, V B; Chirkina, I V; Shcheglov, M Iu

    2009-01-01

    Based on thermodynamic studies, the authors conducted laboratory experiments on searching optimal composition of leaching reagents solution for soils decontamination, when contaminated with Cs-137, of activity coefficient for caesium sulfate microquantities in macrocomponents solutions. The method could be used for modelling the radionuclides phase equillibrium and relocations in soils.

  5. Missing links in the root-soil organic matter continuum

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, Sarah L. [Argonne National Laboratory (ANL); Iversen, Colleen M [ORNL

    2009-01-01

    The soil environment remains one of the most complex and poorly understood research frontiers in ecology. Soil organic matter (SOM), which spans a continuum from fresh detritus to highly processed, mineral-associated organic matter, is the foundation of sustainable terrestrial ecosystems. Heterogeneous SOM pools are fueled by inputs from living and dead plants, driven by the activity of micro- and mesofauna, and are shaped by a multitude of abiotic factors. The specialization required to measure unseen processes that occur on a wide range of spatial and temporal scales has led to the partitioning of soil ecology research across several disciplines. In the organized oral session 'Missing links in the root-soil organic matter continuum' at the annual Ecological Society of America meeting in Albuquerque, NM, USA, we joined the call for greater communication and collaboration among ecologists who work at the root-soil interface (e.g. Coleman, 2008). Our goal was to bridge the gap between scientific disciplines and to synthesize disconnected pieces of knowledge from root-centric and soil-centric studies into an integrated understanding of belowground ecosystem processes. We focused this report around three compelling themes that arose from the session: (1) the influence of the rhizosphere on SOM cycling, (2) the role of soil heterotrophs in driving the transformation of root detritus to SOM, and (3) the controlling influence of the soil environment on SOM dynamics. We conclude with a discussion of new approaches for gathering data to bridge gaps in the root-SOM continuum and to inform the next generation of ecosystem models. Although leaf litter has often been considered to be the main source of organic inputs to soil, Ann Russell synthesized a convincing body of work demonstrating that roots, rather than surface residues, control the accumulation of SOM in a variety of ecosystems. Living roots, which are chemically diverse and highly dynamic, also influence a

  6. Litter decomposition rate and soil organic matter quality in a patchwork heathland of Southern Norway

    Science.gov (United States)

    Certini, G.; Vestgarden, L. S.; Forte, C.; Tau Strand, L.

    2014-07-01

    Norwegian heathland soils, although scant and shallow, are major reservoirs of carbon (C). We aimed at assessing whether vegetation cover and, indirectly, its driving factor soil drainage are good proxies for soil organic matter (SOM) composition and dynamics in a typical heathland area of Southern Norway consisting in a patchwork of three different types of vegetation, dominated by Calluna, Molinia, or Sphagnum. Such vegetation covers were clearly associated to microtopographic differences, which in turn dictated differences in soil moisture regime, Calluna growing in the driest sites, Sphagnum in the wettest, and Molinia in sites with intermediate moisture. Litter decomposition was followed over a period of 1 year, by placing litterbags filled with biomass from each dominant species under each type of vegetation cover. The composition of the living biomass, the bulk SOM and some extractable fractions of SOM were investigated by chemical methods and solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Litter decomposition was faster for Molinia and Calluna, irrespective of the vegetation cover of the site where they were placed. Sphagnum litter decomposed very slowly, especially under Calluna, where the soil environment is by far more oxidising than under itself. In terms of SOM quality, Calluna covered areas showed the greatest differences from the others, in particular a much higher contribution from lipids and aliphatic biopolymers, apparently related to biomass composition. Our findings showed that in the studied environment litter decomposition rate and SOM composition are actually dependent on vegetation cover and/or soil drainage. On this basis, monitoring changes in the patchwork of vegetation types in boreal heathlands could be a reliable cost-effective way to account for modifications in the SOM potential to last induced by climate change.

  7. Composition and Diversity of Soil Arthropods of Rajegwesi Meru Betiri National Park

    Directory of Open Access Journals (Sweden)

    Hasan Zayadi

    2013-09-01

    Full Text Available Meru Betiri National Park (MBNP is one of the nature conservation area that has the potential of flora, fauna, and ecosystems that could develop as a nature-based tourism attraction. The existence of certain indicator species was related to estimation of stress level and disturbance on ecosystem stability for making strategic decisions about the restoration in this area. One of the important indicator species at forest ecosystem were soil arthropods. Aim this research were analyzed composition and diversity of soil arthropods at Rajegwesi, MBNP areas. The methods in this research used pitfall trap, measurement of distribution structure and soil arthropods composition based on the Shannon - Wiener index, Morisita similarity index and Importance Value Index (IVI. The number of families and individuals of soil arthropods found in the coastal area of Rajegwesi consists of 10 order with 21 families (702 individual. The number of individuals of the order Hymenoptera, Coleoptera, Collembola and Araneida was more widely found. Soil arthropods diversity index on each land use indicated that soil arthropod diversity in these areas were moderate. Soil arthropod community of orchards and forest had a similarity of species composition, whereas soil arthropod community of savanna had a similarity of species composition with paddy fields.

  8. Greenhouse gas fluxes from agricultural soils under organic and non-organic management — A global meta-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Colin, E-mail: colin.skinner@fibl.org [Research Institute of Organic Agriculture (FiBL), Ackerstrasse 21, 5070 Frick (Switzerland); Gattinger, Andreas, E-mail: andreas.gattinger@fibl.org [Research Institute of Organic Agriculture (FiBL), Ackerstrasse 21, 5070 Frick (Switzerland); Muller, Adrian, E-mail: adrian.mueller@fibl.org [Research Institute of Organic Agriculture (FiBL), Ackerstrasse 21, 5070 Frick (Switzerland); Mäder, Paul, E-mail: paul.maeder@fibl.org [Research Institute of Organic Agriculture (FiBL), Ackerstrasse 21, 5070 Frick (Switzerland); Fließbach, Andreas, E-mail: andreas.fliessbach@fibl.org [Research Institute of Organic Agriculture (FiBL), Ackerstrasse 21, 5070 Frick (Switzerland); Stolze, Matthias, E-mail: matthias.stolze@fibl.org [Research Institute of Organic Agriculture (FiBL), Ackerstrasse 21, 5070 Frick (Switzerland); Ruser, Reiner, E-mail: reiner.ruser@uni-hohenheim.de [Fertilisation and Soil Matter Dynamics (340i), Institute of Crop Science, University of Hohenheim, Fruwirthstraße 20, 70599 Stuttgart (Germany); Niggli, Urs, E-mail: urs.niggli@fibl.org [Research Institute of Organic Agriculture (FiBL), Ackerstrasse 21, 5070 Frick (Switzerland)

    2014-01-01

    It is anticipated that organic farming systems provide benefits concerning soil conservation and climate protection. A literature search on measured soil-derived greenhouse gas (GHG) (nitrous oxide and methane) fluxes under organic and non-organic management from farming system comparisons was conducted and followed by a meta-analysis. Up to date only 19 studies based on field measurements could be retrieved. Based on 12 studies that cover annual measurements, it appeared with a high significance that area-scaled nitrous oxide emissions from organically managed soils are 492 ± 160 kg CO{sub 2} eq. ha{sup −1} a{sup −1} lower than from non-organically managed soils. For arable soils the difference amounts to 497 ± 162 kg CO{sub 2} eq. ha{sup −1} a{sup −1}. However, yield-scaled nitrous oxide emissions are higher by 41 ± 34 kg CO{sub 2} eq. t{sup −1} DM under organic management (arable and use). To equalize this mean difference in yield-scaled nitrous oxide emissions between both farming systems, the yield gap has to be less than 17%. Emissions from conventionally managed soils seemed to be influenced mainly by total N inputs, whereas for organically managed soils other variables such as soil characteristics seemed to be more important. This can be explained by the higher bioavailability of the synthetic N fertilisers in non-organic farming systems while the necessary mineralisation of the N sources under organic management leads to lower and retarded availability. Furthermore, a higher methane uptake of 3.2 ± 2.5 kg CO{sub 2} eq. ha{sup −1} a{sup −1} for arable soils under organic management can be observed. Only one comparative study on rice paddies has been published up to date. All 19 retrieved studies were conducted in the Northern hemisphere under temperate climate. Further GHG flux measurements in farming system comparisons are required to confirm the results and close the existing knowledge gaps. - Highlights: • Lower area-scaled nitrous

  9. Microbial Contribution to Organic Carbon Sequestration in Mineral Soil

    Science.gov (United States)

    Soil productivity and sustainability are dependent on soil organic matter (SOM). Our understanding on how organic inputs to soil from microbial processes become converted to SOM is still limited. This study aims to understand how microbes affect carbon (C) sequestration and the formation of recalcit...

  10. Organic soil production from urban soil, spent mushroom substrate, and other additives

    Science.gov (United States)

    Pham, Nhung Thi Ha

    2017-09-01

    In recent years, spent mushroom substrate (SMS) is becoming the huge problem in environmental pollution issues from mushroom production. However, SMS is also a nutrient-rich ogranic material with available nutrients and high porosity. Therefore, the value of products made from SMS should be exploited to take full advantage of agricultural by-product, support organic agriculture development without environmental pollution. The research has built 5 experimental formulas (4 mixed formulas and 1 control formulas with only urban soil). The analysis results of soil samples from mixed formulas and the control formula witness a significant increase in moisture and OM of mixed formulas (moisture from 36-42%, OM from 5.5-6.9%) after 20 treatment days, and N-P-K contents are also improved remarkably. 60 days later, soil nutrients in mixed formulas continue to rise, with highest OM (8.679%) at CT1; N (0.154%) at CT4; K2O (0,698%) and P2O5 (0,172%) at CT3, in addition, heavy metal contents in all formulas are under standard limit. Synthetic assessment of all norms indicates that the best organic soil product comes from CT3. The pak choi planting experiments are performed show that the growth of plants cultivated on organic soil products made from mixed formulas are much better than plants are grown on initially soil, and they also have no pestilent insect. Specially, pak choi planted on organic soil from CT3 have sharp developing with excellent tolerance ability, quantity and area of leaves are high. Thus, CT3 is the most suitable formula to increase soil nutrients, to solve spent mushroom subtrate streament problems after harvest, and for sustainable agricultural development.

  11. Changes in Soil Organic Matter Abundance, Molecular Composition, and Diversity in an Arid Ecosystem in Response to Long-term Elevated CO2 Manipulation.

    Science.gov (United States)

    Hess, N. J.; Tfaily, M.; Evans, R. D.; Koyama, A.

    2017-12-01

    Little is known about how soils in arid ecosystems will respond to rising atmospheric CO2 concentration yet arid and semi-arid ecosystems cover more than 40% of Earth's land surface. Previous work in the Mojave Desert (Evans et al., 2014 Nature Climate Change) reported higher soil organic carbon (SOC) and total nitrogen (N) concentrations following 10 years exposure to elevated atmospheric CO2 at the Nevada Desert Free-Air-Carbon dioxide-Enrichment (FACE) Facility (NDFF). In this study, we investigated potential mechanisms that resulted in increased SOC and total N accumulation and stabilization using high resolution mass spectrometry at the NDFF site. Samples were collected from soil profiles to 1 m in depth with a 0.2 m a increment under the dominant evergreen shrub Larrea tridentata. The differences in the molecular composition and diversity of soil organic matter (SOM) were more evident in surface soils and declined with depth, and were consistent with higher SOC and total N concentrations under elevated than ambient CO2. Our molecular analysis also suggested increased root exudation and/or microbial necromass from stabilization of labile C and N contributed to SOM and N stocks. Increased microbial activity and metabolism under elevated CO2 compared to ambient plots suggested that elevated CO2 altered microbial carbon (C) use patterns, reflecting changes in the quality and quantity of SOC inputs. We found that plant-derived compounds were primary substrates for microbial activity under elevated CO2 and microbial products were the main constituents of stabilized SOM. Our results suggest that arid ecosystems are a potential large C sink under elevated CO2, give the extensive coverage of the land surface, and that labile compounds are transformed to stable SOM via microbial processes. Arid systems are limited by water, and thus may have a different C storage potential under changing climates than other ecosystems that are limited by nitrogen or phosphorus.

  12. Soil types effect on grape and wine composition in Helan Mountain area of Ningxia.

    Directory of Open Access Journals (Sweden)

    Rui Wang

    Full Text Available Different soil types can significantly affect the composition of wine grapes and the final wine product. In this study, the effects of soil types on the composition of Cabernet Sauvignon grapes and wine produced in the Helan Mountains were evaluated. Three different representative soil types--aeolian, sierozem and irrigation silting soil were studied. The compositions of grapes and wines were measured, and in addition, the weights of 100-berry samples were determined. The grapes that grown on the aeolian and sierozem soils matured sooner than those grown on the irrigation silting soil. The highest sugar content, total soluble solids content, sugar to acid ratio and anthocyanin content were found in the grapes that grown on the aeolian soil. The wine produced from this soil had improved chroma and tone and higher-quality phenols. The grapes grown on the sierozem soil had the highest total phenol and tannin contents, which affected the wine composition. The grapes grown on the irrigation silting soil had higher acidities, but the remaining indices were lower. In addition, the grapes grown on the aeolian soil resulted in wines with better chroma and aroma. The sierozem soil was beneficial for the formation of wine tannins and phenols and significantly affected the wine composition. The quality of the grapes from the irrigation silting soil was relatively low, resulting in lower-quality wine.

  13. Soil types effect on grape and wine composition in Helan Mountain area of Ningxia.

    Science.gov (United States)

    Wang, Rui; Sun, Quan; Chang, Qingrui

    2015-01-01

    Different soil types can significantly affect the composition of wine grapes and the final wine product. In this study, the effects of soil types on the composition of Cabernet Sauvignon grapes and wine produced in the Helan Mountains were evaluated. Three different representative soil types--aeolian, sierozem and irrigation silting soil were studied. The compositions of grapes and wines were measured, and in addition, the weights of 100-berry samples were determined. The grapes that grown on the aeolian and sierozem soils matured sooner than those grown on the irrigation silting soil. The highest sugar content, total soluble solids content, sugar to acid ratio and anthocyanin content were found in the grapes that grown on the aeolian soil. The wine produced from this soil had improved chroma and tone and higher-quality phenols. The grapes grown on the sierozem soil had the highest total phenol and tannin contents, which affected the wine composition. The grapes grown on the irrigation silting soil had higher acidities, but the remaining indices were lower. In addition, the grapes grown on the aeolian soil resulted in wines with better chroma and aroma. The sierozem soil was beneficial for the formation of wine tannins and phenols and significantly affected the wine composition. The quality of the grapes from the irrigation silting soil was relatively low, resulting in lower-quality wine.

  14. Soil Types Effect on Grape and Wine Composition in Helan Mountain Area of Ningxia

    Science.gov (United States)

    Wang, Rui; Sun, Quan; Chang, Qingrui

    2015-01-01

    Different soil types can significantly affect the composition of wine grapes and the final wine product. In this study, the effects of soil types on the composition of Cabernet Sauvignon grapes and wine produced in the Helan Mountains were evaluated. Three different representative soil types—aeolian, sierozem and irrigation silting soil were studied. The compositions of grapes and wines were measured, and in addition, the weights of 100-berry samples were determined. The grapes that grown on the aeolian and sierozem soils matured sooner than those grown on the irrigation silting soil. The highest sugar content, total soluble solids content, sugar to acid ratio and anthocyanin content were found in the grapes that grown on the aeolian soil. The wine produced from this soil had improved chroma and tone and higher-quality phenols. The grapes grown on the sierozem soil had the highest total phenol and tannin contents, which affected the wine composition. The grapes grown on the irrigation silting soil had higher acidities, but the remaining indices were lower. In addition, the grapes grown on the aeolian soil resulted in wines with better chroma and aroma. The sierozem soil was beneficial for the formation of wine tannins and phenols and significantly affected the wine composition. The quality of the grapes from the irrigation silting soil was relatively low, resulting in lower-quality wine. PMID:25706126

  15. Variations of the natural isotopic composition (15N) of mineral nitrogen from calcareous soils, studied during incubation experiment and on the field

    International Nuclear Information System (INIS)

    Mariotti, A.; Guillemot, J.

    1980-01-01

    This study was intended to follow the variations of isotope composition of mineral nitrogen formed during incubation of calcareous soils (rendzine), humidity and temperature conditions approximating natural ones. We compared the isotope composition with that of mineral nitrogen formed in a lysimeter cut out from a natural soil with the same pedological features. During the incubation experiments, two steps were recognized. A step with production of nitrates and nitrites depleted in 15 N and a second step where the isotope composition leans towards an equilibrium value. During the first step, the 15 N depletion for the sum NO 3 + NO 2 correlates with a 15 N enrichment for ammonium. On the whole, the total mineral nitrogen isotope composition is approximately constant. This first step corresponds also to a great speed of nitrification, to the presence of nitrite and to a large evolution (production or use) of ammonium. On the contrary, nitrites have disappeared and ammonium is in dynamic equilibrium (constant concentration) when the delta 15 N of nitrates is stabilized. In another set of experiments, with the same conditions, small quantity of a nitrogen substrate (vegetal proteins or amino acids) easily mineralizable, was added to the soil: the 15 N depletion of NO 3 + NO 2 formed during the first step is much greater than with the mere soil. It is concluded that the initial step corresponds to the fast mineralization of a very labile organic component which could be, for the mere soil, the microbial biomass destroyed during air-drying of sample before incubations: this could correspond to the 'flush effect'. On the contrary, the step when nitrates becomes constant could correspond to the mineralization (slower and more regular) of an another organic pool, perhaps part of humified organic matter [fr

  16. The sources and composition of humus in some soils of West Antarctica

    Science.gov (United States)

    Abakumov, E. V.

    2010-05-01

    Original data on humus-forming substances and their elemental and biochemical compositions in Antarctic soils are discussed. Mosses, lichens, algae, remains of higher vascular plants, and penguin guano of two types differ considerably in their chemical compositions. This leads to significant differences in the formation of humic substances in plant materials themselves in the course of their transformation. However, no significant differences in the composition of humus in the fine earth of soils developing under different humus-forming materials have been revealed, which may be related to the extremely low rates of humification. Significant differences between the soils of Antarctic landscapes proper and the soils of the Subantarctic King George Island are only observed in the humus enrichment with nitrogen. The soils of Antarctica are low-humus soils with the humate-fulvate or fulvate types of humus.

  17. Soil organic matter chemistry changes upon secondary succession in Imperata Grasslands , Indonesia: A pyrolysis - GC/MS study

    NARCIS (Netherlands)

    Yassir, I.; Buurman, P.

    2012-01-01

    The chemical composition of soil organic matter (SOM) following secondary succession in Imperata grassland was investigated by Pyrolysis-Gas Chromatography/Mass Spectrometry (GC/MS). We studied 46 samples from different stages of succession using plots that last burned 3 and 9 years previously,

  18. Soil Carbon: Compositional and Isotopic Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Moran, James J.; Alexander, M. L.; Laskin, Alexander

    2016-11-01

    This is a short chapter to be included in the next edition of the Encyclopedia of Soil Science. The work here describes techniques being developed at PNNL for investigating organic carbon in soils. Techniques discussed include: laser ablation isotope ratio mass spectrometry, laser ablation aerosol mass spectrometry, and nanospray desorption electrospray ionization mass spectrometry.

  19. Application of Remote Sensing for Mapping Soil Organic Matter Content

    Directory of Open Access Journals (Sweden)

    Bangun Muljo Sukojo

    2010-10-01

    Full Text Available Information organic content is important in monitoring and managing the environment as well as doing agricultural production activities. This research tried to map soil organic content in Malang using remote sensing technology. The research uses 6 bands of data captured by Landsat TM (Thematic Mapper satellite (band 1, 2, 3, 4, 5, 7. The research focuses on pixels having Normalized Difference Soil Index (NDSI more than 0.3. Ground-truth data were collected by analysing organic content of soil samples using Black-Walkey method. The result of analysis shows that digital number of original satellite image can be used to predict soil organic matter content. The implementation of regression equation in predicting soil organic content shows that 63.18% of research area contains of organic in a moderate category.

  20. Beta particle dose rates to micro-organisms in soil

    International Nuclear Information System (INIS)

    Kabir, M.; Spiers, F.W.; Iinuma, Takeshi.

    1977-01-01

    Studies were made to estimate the beta-particle dose rates to micro-organisms of various sizes in soil. The small insects and organisms living in soil are constantly exposed to beta-radiation arising from naturally occuring radionuclides in soil as in this case no overlying tissue shields them. The technique of measuring beta-particle dose rate consisted of using of a thin plastic scintillator to measure the pulse height distribution as the beta particle traverses the scintillator. The integrated response was determined by the number and size of the photomultiplier pulses. From the data of soil analyses it was estimated that typically about 29% of the beta particles emitted per gm. of soil were contributed by the U/Ra series, 21% by the Th series and about 50% by potassium. By combining the individual spectra of these three radionuclides in the proportion found in a typical soil, a resultant spectrum was computed representing the energy distribution of the beta particles. The dose rate received by micro-organisms of different shape and size in soil was derived from the equilibrium dose rates combined with a 'Geometrical Factor' of the organisms. For small organisms, the dose rates did not vary between the spherical and cylindrical types, but in the case of larger organisms, the dose rates were found to be greater for the spherical types of the same diameter. (auth.)

  1. Organic nitrogen components in soils from southeast China*

    Science.gov (United States)

    Chen, Xian-you; Wu, Liang-huan; Cao, Xiao-chuang; Zhu, Yuan-hong

    2013-01-01

    Objective: To investigate the amounts of extractable organic nitrogen (EON), and the relationships between EON and total extractable nitrogen (TEN), especially the amino acids (AAs) adsorbed by soils, and a series of other hydrolyzed soil nitrogen indices in typical land use soil types from southeast China. Under traditional agricultural planting conditions, the functions of EON, especially AAs in the rhizosphere and in bulk soil zones were also investigated. Methods: Pot experiments were conducted using plants of pakchoi (Brassica chinensis L.) and rice (Oryza sativa L.). In the rhizosphere and bulk soil zone studies, organic nitrogen components were extracted with either distilled water, 0.5 mol/L K2SO4 or acid hydrolysis. Results: K2SO4-EON constituted more than 30% of TEN pools. K2SO4-extractable AAs accounted for 25% of EON pools and nearly 10% of TEN pools in rhizosphere soils. Overall, both K2SO4-EON and extractable AAs contents had positive correlations with TEN pools. Conclusions: EON represented a major component of TEN pools in garden and paddy soils under traditional planting conditions. Although only a small proportion of the EON was present in the form of water-extractable and K2SO4-extractable AAs, the release of AAs from soil exchangeable sites might be an important source of organic nitrogen (N) for plant growth. Our findings suggest that the content of most organic forms of N was significantly greater in rhizosphere than in bulk soil zone samples. However, it was also apparent that the TEN pool content was lower in rhizosphere than in bulk soil samples without added N. PMID:23549843

  2. Effects of Pig Manure Organic Fertilizer Application on Available Nutrient Content and Soil Aggregate Distribution in Fluvo-aquic Soil

    Directory of Open Access Journals (Sweden)

    SHI Wen-xuan

    2017-08-01

    Full Text Available This paper focuses on environmental risk caused by livestock manure disorderly discharged from integrated livestock and poultry industry. 2-year pot experiment was carried out to study the effects of pig manure organic fertilizer on fluvo-aquic soil organic carbon, available nutrient content and soil aggregate distribution, which designed in 5 levels of organic fertilizer application(0, 6.7, 13.3, 26.7, 40.0 g·kg-1 soil. The results showed that the organic carbon, alkali-hydrolyzable nitrogen, available P and available K contents in soil were enhanced with organic fertilizer application increasing, and the indicators of soil were increased significantly in second year, such as organic carbon content was 2.7%~54.0% higher than that of the first year, alkali-hydrolyzable nitrogen content was higher 6.7%~34.6%, available P content was higher 36.8%~159.5% and available K content was higher 20.3%~35.7%. There was a significant linear relationship between soil organic carbon content and external organic carbon input. Organic fertilizer application could significantly improve lettuce yield, and it had a significant effect. The soil micro-aggregate contents for 0.053~0.25 mm and 0.5 mm soil macro-aggregates were increased with organic fertilizer application increasing. Organic fertilizer application could promote soil macro-aggregates formation, when the pig manure organic fertilizer applied 40.0 g·kg-1 soil, the contents of >0.25 mm soil aggregates reached maximum, and also the mean weight diameter(MWD and geometric average diameter(GWD of soil aggregates were higher than that of other treatments, the soil agglomeration became more stronger and the soil structure became more stable.

  3. Effects of organic and inorganic amendments on soil erodibility

    Directory of Open Access Journals (Sweden)

    Nutullah Özdemir

    2015-10-01

    Full Text Available The objective of the present investigation is to find out the effect of incorporating of various organic and inorganic matter sources such as lime (L, zeolit (Z, polyacrylamide (PAM and biosolid (BS on the instability index. A bulk surface (0–20 cm depth soil sample was taken from Samsun, in northern part of Turkey. Some soil properties were determined as follows; fine in texture, modarete in organic matter content, low in pH and free of alkaline problem. The soil samples were treated with the inorganic and organic materials at four different levels including the control treatments in a randomized factorial block design. The soil samples were incubated for ten weeks. After the incubation period, corn was grown in all pots. The results can be summarized as organic and inorganic matter treatments increased structure stability and decreased soil erodibility. Effectiveness of the treatments varied depending on the types and levels of organic and inorganic materials.

  4. Organic matter composition and substrate diversity under elevated CO2 in the Mojave Desert

    Science.gov (United States)

    Tfaily, M. M.; Hess, N. J.; Koyama, A.; Evans, R. D.

    2016-12-01

    Little is known about how rising atmospheric CO2 concentration will impact long-term plant biomass or the dynamics of soil organic matter (SOM) in arid ecosystems. In this study, we investigated the change in the molecular composition of SOM by high resolution mass spectrometry after 10 years exposure to elevated atmospheric CO2 concentrations at the Nevada Desert FACE Facility. Samples were collected from soil profiles from 0 to 1m in 0.2m increments under the dominant evergreen shrub (Larrea tridentata). The differences in the composition of SOM were more evident in soils close to the surface and consistent with higher bulk soil organic carbon (C) and total nitrogen (N) concentrations under elevated than ambient CO2, reflecting increased net productivity of shrubs under elevated CO2, which could be attributed to increased litter input from above-ground biomass and/or shallow roots, root exudation and/or microbial residues. This was further supported by the significant increase in the abundance of amino sugars-, protein- and carbohydrate-like compounds. These compounds are involved in diverse pathways ranging from sugars and amino-acid metabolism to lipid biosynthesis. This indicates increased activity and metabolism under elevated CO2 and suggests that elevated CO2 have altered microbial C use patterns, reflecting changes in the quality and quantity of soil C inputs. A significant increase in the mineral-bound soil organic C was also observed in the surface soils under elevated CO2. This was accompanied by increased microbial residues as identified by mass spectrometry that supports microbial lipid analysis, and reflecting accelerated microbial turnover under elevated CO2. Fungal neutral lipid fatty acids (NLFA) abundance doubled under elevated CO2. When provided with excess labile compounds, such as root exudates, and with limited supply of nutrients, fungi assimilate the excess labile C and store it as NLFA likely contributing to increased total N

  5. Fate of lignin, cutin and suberin in soil organic matter fractions - an incubation experiment

    Science.gov (United States)

    Mueller, Carsten W.; Mueller, Kevin E.; Freeman, Katherine H.; Ingrid, Kögel-Knabner

    2010-05-01

    The turnover of soil organic matter (SOM) is controlled by its chemical composition, its spatial accessibility and the association with the mineral phase. Separation of bulk soils by physical fractionation and subsequent chemical analysis of these fractions should give insights to how compositional differences in SOM drive turnover rates of different size-defined carbon pools. The main objective of this study was to elucidate the relative abundance and recalcitrance of lignin, cutin and suberin in aggregated bulk soils and SOM fractions in the course of SOM decomposition. Bulk soils and physically-separated size fractions (sand, silt and clay) of the Ah horizon of a forest soil (under Picea abies L.Karst) were parallel incubated over a period of one year. In order to differentiate between particulate OM (POM) and mineral-associated SOM the particle size fractions were additionally separated by density after the incubation experiment. We used solid-state 13C-CPMAS NMR spectroscopy and GC-MS (after copper oxide oxidation and solvent extraction) to analyze the composition of the incubated samples. The abundance and isotopic composition (including 13C and 14C) of the respired CO2 further enabled us to monitor the dynamics of SOM mineralization. This approach allowed for differentiating between C stabilization of soil fractions due to accessibility/aggregation and to biochemical recalcitrance at different scales of resolution (GC-MS, NMR). We found a relative enrichment of alkyl C and decreasing lignin contents in the order of sand particulate OM (POM). For the fresh particulate OM (POM) of the sand fraction a clear decay of lignin was observed in the course of the incubation experiment, indicated by decreasing C/V and increasing ac/alV ratios. A relative decrease of aliphatic C in the incubated fractions compared to the incubated bulk soils showed the preferential mineralization of less recalcitrant C compounds that were spatially inaccessible in aggregates of the bulk

  6. Soil structure and microbial activity dynamics in 20-month field-incubated organic-amended soils

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Schjønning, Per; Møldrup, Per

    2014-01-01

    to determine compressive strength. During incubation, the amount of WDC depended on soil carbon content while the trends correlated with moisture content. Organic amendment only yielded modest decreases (mean of 14% across all sampling times and soils) in WDC, but it was sufficient to stimulate the microbial......Soil structure formation is essential to all soil ecosystem functions and services. This study aims to quantify changes in soil structure and microbial activity during and after field incubation and examine the effect of carbon, organic amendment and clay on aggregate characteristics. Five soils...... community (65–100% increase in FDA). Incubation led to significant macroaggregate formation (>2 mm) for all soils. Friability and strength of newly-formed aggregates were negatively correlated with clay content and carbon content, respectively. Soil workability was best for the kaolinite-rich soil...

  7. Soil contamination with cadmium, consequences and remediation using organic amendments.

    Science.gov (United States)

    Khan, Muhammad Amjad; Khan, Sardar; Khan, Anwarzeb; Alam, Mehboob

    2017-12-01

    Cadmium (Cd) contamination of soil and food crops is a ubiquitous environmental problem that has resulted from uncontrolled industrialization, unsustainable urbanization and intensive agricultural practices. Being a toxic element, Cd poses high threats to soil quality, food safety, and human health. Land is the ultimate source of waste disposal and utilization therefore, Cd released from different sources (natural and anthropogenic), eventually reaches soil, and then subsequently bio-accumulates in food crops. The stabilization of Cd in contaminated soil using organic amendments is an environmentally friendly and cost effective technique used for remediation of moderate to high contaminated soil. Globally, substantial amounts of organic waste are generated every day that can be used as a source of nutrients, and also as conditioners to improve soil quality. This review paper focuses on the sources, generation, and use of different organic amendments to remediate Cd contaminated soil, discusses their effects on soil physical and chemical properties, Cd bioavailability, plant uptake, and human health risk. Moreover, it also provides an update of the most relevant findings about the application of organic amendments to remediate Cd contaminated soil and associated mechanisms. Finally, future research needs and directions for the remediation of Cd contaminated soil using organic amendments are discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Organic carbon and nitrogen availability determine bacterial community composition in paddy fields of the Indo-Gangetic plain.

    Science.gov (United States)

    Kumar, Arvind; Rai, Lal Chand

    2017-07-01

    Soil quality is an important factor and maintained by inhabited microorganisms. Soil physicochemical characteristics determine indigenous microbial population and rice provides food security to major population of the world. Therefore, this study aimed to assess the impact of physicochemical variables on bacterial community composition and diversity in conventional paddy fields which could reflect a real picture of the bacterial communities operating in the paddy agro-ecosystem. To fulfill the objective; soil physicochemical characterization, bacterial community composition and diversity analysis was carried out using culture-independent PCR-DGGE method from twenty soils distributed across eight districts. Bacterial communities were grouped into three clusters based on UPGMA cluster analysis of DGGE banding pattern. The linkage of measured physicochemical variables with bacterial community composition was analyzed by canonical correspondence analysis (CCA). CCA ordination biplot results were similar to UPGMA cluster analysis. High levels of species-environment correlations (0.989 and 0.959) were observed and the largest proportion of species data variability was explained by total organic carbon (TOC), available nitrogen, total nitrogen and pH. Thus, results suggest that TOC and nitrogen are key regulators of bacterial community composition in the conventional paddy fields. Further, high diversity indices and evenness values demonstrated heterogeneity and co-abundance of the bacterial communities.

  9. Clay minerals, metallic oxides and oxy-hydroxides and soil organic carbon distribution within soil aggregates in temperate forest soils

    Science.gov (United States)

    Gartzia-Bengoetxea, Nahia; Fernández-Ugalde, Oihane; Virto, Iñigo; Arias-González, Ander

    2017-04-01

    Soil mineralogy is of primary importance for key environmental services provided by soils like carbon sequestration. However, current knowledge on the effects of clay mineralogy on soil organic carbon (SOC) stabilization is based on limited and conflicting data. In this study, we investigated the relationship between clay minerals, metallic oxides and oxy-hydroxides and SOC distribution within soil aggregates in mature Pinus radiata D.Don forest plantations. Nine forest stands located in the same geographical area of the Basque Country (North of Spain) were selected. These stands were planted on different parent material (3 on each of the following: sandstone, basalt and trachyte). There were no significant differences in climate and forest management among them. Moreover, soils under these plantations presented similar content of clay particles. We determined bulk SOC storage, clay mineralogy, the content of Fe-Si-Al-oxides and oxyhydroxides and the distribution of organic C in different soil aggregate sizes at different soil depths (0-5 cm and 5-20 cm). The relationship between SOC and abiotic factors was investigated using a factor analysis (PCA) followed by stepwise regression analysis. Soils developed on sandstone showed significantly lower concentration of SOC (29 g C kg-1) than soils developed on basalts (97 g C kg-1) and trachytes (119 g C kg-1). The soils on sandstone presented a mixed clay mineralogy dominated by illite, with lesser amounts of hydroxivermiculite, hydrobiotite and kaolinite, and a total absence of interstratified chlorite/vermiculite. In contrast, the major crystalline clay mineral identified in the soils developed on volcanic rocks was interstratified chlorite/vermiculite. Nevertheless, no major differences were observed between basaltic and trachytic soils in the clay mineralogy. The selective extraction of Fe showed that the oxalate extractable iron was significantly lower in soils on sandstone (3.7%) than on basalts (11.2%) and

  10. Role of primary substrate composition and concentration on attenuation of trace organic chemicals in managed aquifer recharge systems

    KAUST Repository

    Alidina, Mazahirali; Li, Dong; Ouf, Mohamed; Drewes, Jorg

    2014-01-01

    This study was undertaken to investigate the role of primary substrate composition and concentration on the attenuation of biodegradable emerging trace organic chemicals (TOrCs) in simulated managed aquifer recharge (MAR) systems. Four sets of soil

  11. Vegetation composition and soil nutrients status from polyculture to ...

    African Journals Online (AJOL)

    use

    The values for soil moisture, organic carbon, nitrogen, and phosphorus were markedly higher at high ... temperature, humidity and light interception) was measured at the .... particles (clay) help in retention of more organic C and. TKN in soil of ...

  12. Effects of simulated acid rain on soil fauna community composition and their ecological niches.

    Science.gov (United States)

    Wei, Hui; Liu, Wen; Zhang, Jiaen; Qin, Zhong

    2017-01-01

    Acid rain is one of the severest environmental issues globally. Relative to other global changes (e.g., warming, elevated atmospheric [CO 2 ], and nitrogen deposition), however, acid rain has received less attention than its due. Soil fauna play important roles in multiple ecological processes, but how soil fauna community responds to acid rain remains less studied. This microcosm experiment was conducted using latosol with simulated acid rain (SAR) manipulations to observe potential changes in soil fauna community under acid rain stress. Four pH levels, i.e., pH 2.5, 3.5, 4.5, and 5.5, and a neutral control of pH 7.0 were set according to the current pH condition and acidification trend of precipitation in southern China. As expected, we observed that the SAR treatments induced changes in soil fauna community composition and their ecological niches in the tested soil; the treatment effects tended to increase as acidity increased. This could be attributable to the environmental stresses (such as acidity, porosity and oxygen supply) induced by the SAR treatments. In addition to direct acidity effect, we propose that potential changes in permeability and movability of water and oxygen in soils induced by acid rain could also give rise to the observed shifts in soil fauna community composition. These are most likely indirect pathways of acid rain to affect belowground community. Moreover, we found that nematodes, the dominating soil fauna group in this study, moved downwards to mitigate the stress of acid rain. This is probably detrimental to soil fauna in the long term, due to the relatively severer soil conditions in the deep than surface soil layer. Our results suggest that acid rain could change soil fauna community and the vertical distribution of soil fauna groups, consequently changing the underground ecosystem functions such as organic matter decomposition and greenhouse gas emissions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. A snapshot of soil water composition as an indicator of contrasted redox environments in a hedged farmland plot.

    Science.gov (United States)

    Albéric, Patrick; Vennink, Aurélie; Cornu, Sophie; Bourennane, Hocine; Bruand, Ary

    2009-10-15

    While soil water composition has long been recognised as being related to soil type (characteristics of the horizons), the influence of structures resulting from agricultural activities (hedges, ditches, wheel ruts, etc) is still under discussion. This work was undertaken to show that a snapshot of spatial variability of the geochemical characteristics of soil water at the scale of a plot can improve our understanding of soil geochemistry in a farmland setting. We selected a 3 hectare hedged plot located on a hillside, limited by a stream and used as pasture where soils have developed in weathered gneiss. The water depth, electrical conductivity, major ions, temperature, pH, dissolved organic carbon (DOC) content, dissolved oxygen content, fluorescence, alkalinity, Fe(2+), Mn(2+), NO(2)(-), Fe(III) and F(-) contents were measured in 62 auger holes randomly drilled on the site. Four sectors were identified in order to describe the distribution of the main geochemical parameters. Electrical conductivity and some major ions, especially sulphate, had larger concentrations near hedges where oxic conditions prevailed. These features were attributed to the impact of the linear anthropogenic network on the circulation of subsurface soil waters and evapo-transpiration and represent sector I. Dissolved Mn was an indicator of well channelled runoff subsurfaces facilitating the circulation of more highly reducing water (sector III), while DOC probably marked areas drained less well, with a prolonged contact time between soil solutions and organic topsoil horizons (sector II). The presence of dissolved Mn and Fe(II) indicates bottomland anoxic conditions (sector IV). It is concluded that a survey of the chemical composition of soil water may be a direct approach to show the influence of permanent structures on current soil properties and dynamics.

  14. (Tropical) soil organic matter modelling: problems and prospects

    NARCIS (Netherlands)

    Keulen, van H.

    2001-01-01

    Soil organic matter plays an important role in many physical, chemical and biological processes. However, the quantitative relations between the mineral and organic components of the soil and the relations with the vegetation are poorly understood. In such situations, the use of models is an

  15. Soil organic matter regulates molybdenum storage and mobility in forests

    Science.gov (United States)

    Marks, Jade A; Perakis, Steven; King, Elizabeth K.; Pett-Ridge, Julie

    2015-01-01

    The trace element molybdenum (Mo) is essential to a suite of nitrogen (N) cycling processes in ecosystems, but there is limited information on its distribution within soils and relationship to plant and bedrock pools. We examined soil, bedrock, and plant Mo variation across 24 forests spanning wide soil pH gradients on both basaltic and sedimentary lithologies in the Oregon Coast Range. We found that the oxidizable organic fraction of surface mineral soil accounted for an average of 33 %of bulk soil Mo across all sites, followed by 1.4 % associated with reducible Fe, Al, and Mn-oxides, and 1.4 % in exchangeable ion form. Exchangeable Mo was greatest at low pH, and its positive correlation with soil carbon (C) suggests organic matter as the source of readily exchangeable Mo. Molybdenum accumulation integrated over soil profiles to 1 m depth (τMoNb) increased with soil C, indicating that soil organic matter regulates long-term Mo retention and loss from soil. Foliar Mo concentrations displayed no relationship with bulk soil Mo, and were not correlated with organic horizon Mo or soil extractable Mo, suggesting active plant regulation of Mo uptake and/or poor fidelity of extractable pools to bioavailability. We estimate from precipitation sampling that atmospheric deposition supplies, on average, over 10 times more Mo annually than does litterfall to soil. In contrast, bedrock lithology had negligible effects on foliar and soil Mo concentrations and on Mo distribution among soil fractions. We conclude that atmospheric inputs may be a significant source of Mo to forest ecosystems, and that strong Mo retention by soil organic matter limits ecosystem Mo loss via dissolution and leaching pathways.

  16. Global Change Effects on Plant-Soil Interactions

    DEFF Research Database (Denmark)

    Dam, Marie

    of this dissertation has been to determine how soil food web structure and function is affected when the quantity and quality of plant input is altered under global change. By studying the abundance and composition of soil organisms, particularly those in the rhizosphere, closely associated with living plants, we...... (Paper III). Furthermore, by way of meta-analysis, the role of organisms in global change effects on ecosystem function is modelled (Paper IV). Among CO2, warming and summer drought, CO2 is the factor most consistently impacting soil organisms. CO2 increases abundance of microorganisms and nematodes...... suggest that not only the global change effects on established ecosystems, but also the global change effects on plant community composition as well as land use management may determine the composition and function of soil food webs in the future....

  17. Using LUCAS topsoil database to estimate soil organic carbon content in local spectral libraries

    Science.gov (United States)

    Castaldi, Fabio; van Wesemael, Bas; Chabrillat, Sabine; Chartin, Caroline

    2017-04-01

    The quantification of the soil organic carbon (SOC) content over large areas is mandatory to obtain accurate soil characterization and classification, which can improve site specific management at local or regional scale exploiting the strong relationship between SOC and crop growth. The estimation of the SOC is not only important for agricultural purposes: in recent years, the increasing attention towards global warming highlighted the crucial role of the soil in the global carbon cycle. In this context, soil spectroscopy is a well consolidated and widespread method to estimate soil variables exploiting the interaction between chromophores and electromagnetic radiation. The importance of spectroscopy in soil science is reflected by the increasing number of large soil spectral libraries collected in the world. These large libraries contain soil samples derived from a consistent number of pedological regions and thus from different parent material and soil types; this heterogeneity entails, in turn, a large variability in terms of mineralogical and organic composition. In the light of the huge variability of the spectral responses to SOC content and composition, a rigorous classification process is necessary to subset large spectral libraries and to avoid the calibration of global models failing to predict local variation in SOC content. In this regard, this study proposes a method to subset the European LUCAS topsoil database into soil classes using a clustering analysis based on a large number of soil properties. The LUCAS database was chosen to apply a standardized multivariate calibration approach valid for large areas without the need for extensive field and laboratory work for calibration of local models. Seven soil classes were detected by the clustering analyses and the samples belonging to each class were used to calibrate specific partial least square regression (PLSR) models to estimate SOC content of three local libraries collected in Belgium (Loam belt

  18. [Variations of soil microbial community composition and enzyme activities with different salinities on Yuyao coast, Zhejiang, China].

    Science.gov (United States)

    Sun, Hui; Zhang, Jian Feng; Xu, Hua Sen; Chen, Guang Cai; Wang, Li Ping

    2016-10-01

    In October 2015, soil samples with different salinity were collected in a coast area in Yuyao, Zhejiang, and soil microbial community composition, soil catalase, urease activities, as well as soil physical and chemical properties were studied. The results showed that Nitrospira took absolute advantage in the bacterial community, and showed good correlations to total potassium. Cladosporium and Fusarium were predominant in the fungal community. Meanwhile, Cladosporium was related to soil urease and total nitrogen, and same correlation was found between Fusarium and soil urease. Catalase activity ranged from 3.52 to 4.56 mL·g -1 , 3.08 to 4.61 mL·g -1 and 5.81 to 6.91 mL·g -1 for soils with heavy, medium and weak salinity, respectively. Catalase activity increased with the soil layer deepening, which was directly related to soil total potassium, and indirectly related to pH, organic matter, total nitrogen and total phosphorus through total potassium. Soil urease activity ranged among 0.04 to 0.52 mg·g -1 , 0.08 to 1.07 mg·g -1 and 0.27 to 8.21 mg·g -1 for each saline soil, respectively. Urease activity decreased with soil layer deepening which was directly related to soil total nitrogen, and was indirectly related to pH, organic matter and total potassium through total nitrogen. The total phosphorus was the largest effect factor on the bacterial community CCA ordination, and the urease was on fungal community.

  19. Soil organism in organic and conventional cropping systems.

    OpenAIRE

    Bettiol, Wagner; Ghini, Raquel; Galvão, José Abrahão Haddad; Ligo, Marcos Antônio Vieira; Mineiro, Jeferson Luiz de Carvalho

    2002-01-01

    Despite the recent interest in organic agriculture, little research has been carried out in this area. Thus, the objective of this study was to compare, in a dystrophic Ultisol, the effects of organic and conventional agricultures on soil organism populations, for the tomato (Lycopersicum esculentum) and corn (Zea mays) crops. In general, it was found that fungus, bacterium and actinomycet populations counted by the number of colonies in the media, were similar for the two cropping systems. C...

  20. Rain-induced changes in soil CO2 flux and microbial community composition in a tropical forest of China.

    Science.gov (United States)

    Deng, Qi; Hui, Dafeng; Chu, Guowei; Han, Xi; Zhang, Quanfa

    2017-07-17

    Rain-induced soil CO 2 pulse, a rapid excitation in soil CO 2 flux after rain, is ubiquitously observed in terrestrial ecosystems, yet the underlying mechanisms in tropical forests are still not clear. We conducted a rain simulation experiment to quantify rain-induced changes in soil CO 2 flux and microbial community composition in a tropical forest. Soil CO 2 flux rapidly increased by ~83% after rains, accompanied by increases in both bacterial (~51%) and fungal (~58%) Phospholipid Fatty Acids (PLFA) biomass. However, soil CO 2 flux and microbial community in the plots without litters showed limited response to rains. Direct releases of CO 2 from litter layer only accounted for ~19% increases in soil CO 2 flux, suggesting that the leaching of dissolved organic carbon (DOC) from litter layer to the topsoil is the major cause of rain-induced soil CO 2 pulse. In addition, rain-induced changes in soil CO 2 flux and microbial PLFA biomass decreased with increasing rain sizes, but they were positively correlated with litter-leached DOC concentration rather than total DOC flux. Our findings reveal an important role of litter-leached DOC input in regulating rain-induced soil CO 2 pulses and microbial community composition, and may have significant implications for CO 2 losses from tropical forest soils under future rainfall changes.

  1. Organic carbon, nitrogen and phosphorus contents of some tea soils

    International Nuclear Information System (INIS)

    Ahmed, M.S.; Zamir, M.R.; Sanauallah, A.F.M.

    2005-01-01

    Soil samples were collected from Rungicherra Tea-Estate of Moulvibazar district, Bangladesh. Organic carbon, organic matter, total nitrogen and available phosphorus content of the collected soil of different topographic positions have been determined. The experimental data have been analyzed statistically and plotted against topography and soil depth. Organic carbon and organic matter content varied from 0.79 to 1.24% and 1.37 to 2.14%. respectively. Total nitrogen and available phosphorus content of these soils varied respectively from 0.095 to 0.13% and 2.31 to 4.02 ppm. (author)

  2. Assessment of environmental stability of agroserous soil according to indicator of energy potential of organic substances

    Science.gov (United States)

    Murtazina, S. G.; Gaffarova, L. G.; Murtazin, MG

    2018-01-01

    Studies of the group and fractional composition of humus have determineded that the long-term use of soil (for 20 years) without the use of fertilizers (control) leads to a decrease in the content of humic acids and fulvic acids relative to the initial soil, which indicates an increase in mineralization of the soil humus. Under the influence of a long application of high doses of mineral fertilizers, the content of mobile fractions of humic and fulvic acids in the field rotation increases in the humus content. In systems of agriculture that are not balanced by organic matter, which are predominant in most farms of the Republic of Tatarstan, the use of very high doses of potassium fertilizers is not justified energetically. To compensate for losses of humus and its energy potential in calculating organic fertilizers on backgrounds with high doses of mineral fertilizers, the humification coefficients of organic residues should be increased by 30-40% during the rotational period of 5-6 years, which will reduce the loss of energy reserves and thereby improve the ecological stability of soils and the stability of agricultural landscapes

  3. Relationship between soil texture and soil organic matter content on mined-out lands in Berau, East Kalimantan, Indonesia

    Directory of Open Access Journals (Sweden)

    WAHJUNI HARTATI

    2016-01-01

    Full Text Available Abstract. Hartati, Sudarmadji T. 2016. Relationship between soil texture and soil organic matter content on mined-out lands in Berau, East Kalimantan, Indonesia. Nusantara Bioscience 8: 83-88. Post open pit mining may in most cases leave unarable and degraded lands due to heavy soil disturbances and therefore reclamation efforts of such area should be addressed on the revitalization of the soil functions for plant growth. The capability of tropical humid soils, including post open pit mining soils, to support plant growth is largely determined by their organic matter content-nutrient pool, soil aggregation, microbial activity, etc. However, soil organic matter content is, to large extent, governed by the soil clay content which is most likely permanent. This may imply that the soil texture couple with soil organic matter content could be a sound measurement to assess the recovery stages of the mined-out lands in term of soil functions for plant growth. This research was conducted in three sites of reclamation area in Berau, East Kalimantan. Soil texture varied from moderately fine (35-40% clay to fine (40-50% clay and very fine (>50% clay for the BMO, SMO and LMO sites respectively. Soil clay eluviations were found in both of SMO (8 years old revegetation and BMO (>12 years old revegetation sites but not in LMO site. Soil organic matter content ranged from very low (12 and 8 years old revegetation when the organic matter content reaching its maximum. The very fine soil texture does not show clay eluviations process until > 12 years old revegetation even containing the highest organic C content and reaches its maximum at 8-10 years old revegetation.

  4. Oligotrophic bacteria and root disease suppression in organically managed soils

    NARCIS (Netherlands)

    Senechkin, I.V.

    2013-01-01

    The objective of this thesis was to obtain a better understanding of soil health in terms of microbial and chemical characteristics as well as suppression of soil borne plant pathogens. Organic soils were chosen as an appropriate model for studying soil health. Four different organic

  5. The VULCAN Project: Toward a better understanding of the vulnerability of soil organic matter to climate change in permafrost ecosystems

    Science.gov (United States)

    Plaza, C.; Schuur, E.; Maestre, F. T.

    2015-12-01

    Despite much recent research, high uncertainty persists concerning the extent to which global warming influences the rate of permafrost soil organic matter loss and how this affects the functioning of permafrost ecosystems and the net transfer of C to the atmosphere. This uncertainty continues, at least in part, because the processes that protect soil organic matter from decomposition and stabilize fresh plant-derived organic materials entering the soil are largely unknown. The objective of the VULCAN (VULnerability of soil organic CArboN to climate change in permafrost and dryland ecosystems) project is to gain a deeper insight into these processes, especially at the molecular level, and to explore potential implications in terms of permafrost ecosystem functioning and feedback to climate change. We will capitalize on a globally unique ecosystem warming experiment in Alaska, the C in Permafrost Experimental Heating Research (CiPEHR) project, which is monitoring soil temperature and moisture, thaw depth, water table depth, plant productivity, phenology, and nutrient status, and soil CO2 and CH4 fluxes. Soil samples have been collected from the CiPEHR experiment from strategic depths, depending on thaw depth, and allow us to examine effects related to freeze/thaw, waterlogging, and organic matter relocation along the soil profile. We will use physical fractionation methods to separate soil organic matter pools characterized by different preservation mechanisms of aggregation and mineral interaction. We will determine organic C and total N content, transformation rates, turnovers, ages, and structural composition of soil organic matter fractions by elemental analysis, stable and radioactive isotope techniques, and nuclear magnetic resonance tools. Acknowledgements: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 654132. Web site: http://vulcan.comule.com

  6. Similar processes but different environmental filters for soil bacterial and fungal community composition turnover on a broad spatial scale.

    Directory of Open Access Journals (Sweden)

    Nicolas Chemidlin Prévost-Bouré

    Full Text Available Spatial scaling of microorganisms has been demonstrated over the last decade. However, the processes and environmental filters shaping soil microbial community structure on a broad spatial scale still need to be refined and ranked. Here, we compared bacterial and fungal community composition turnovers through a biogeographical approach on the same soil sampling design at a broad spatial scale (area range: 13300 to 31000 km2: i to examine their spatial structuring; ii to investigate the relative importance of environmental selection and spatial autocorrelation in determining their community composition turnover; and iii to identify and rank the relevant environmental filters and scales involved in their spatial variations. Molecular fingerprinting of soil bacterial and fungal communities was performed on 413 soils from four French regions of contrasting environmental heterogeneity (LandesSoil Quality Monitoring Network to evaluate the communities' composition turnovers. The relative importance of processes and filters was assessed by distance-based redundancy analysis. This study demonstrates significant community composition turnover rates for soil bacteria and fungi, which were dependent on the region. Bacterial and fungal community composition turnovers were mainly driven by environmental selection explaining from 10% to 20% of community composition variations, but spatial variables also explained 3% to 9% of total variance. These variables highlighted significant spatial autocorrelation of both communities unexplained by the environmental variables measured and could partly be explained by dispersal limitations. Although the identified filters and their hierarchy were dependent on the region and organism, selection was systematically based on a common group of environmental variables: pH, trophic resources, texture and land use. Spatial autocorrelation was also important at

  7. Soil mixing design methods and construction techniques for use in high organic soils.

    Science.gov (United States)

    2015-06-01

    Organic soils present a difficult challenge for roadway designers and construction due to the high : compressibility of the soil structure and the often associated high water table and moisture content. For : other soft or loose inorganic soils, stab...

  8. Fractionation and characterization of soil organic carbon during transition to organic farming

    Science.gov (United States)

    Abdelrahman, H.; Olk, D.; Cocozza, C.; Miano, T.

    2012-04-01

    The transition from conventional to organic farming is the most difficult period faced by organic growers as it could be characterized by unstable conditions, such as nutrient availability, production reductions, mineralization extents. As soil organic matter (SOM), specifically soil organic carbon (SOC), is known to play important roles in maintenance and improvement of many soil properties, it is important to define its changes during the transition period. Total SOC might not be the suitable tool to track the changes in organically based soil fertility within a 3- to 5-yr transition period. Labile fractions that are important for nutrient cycling and supply are likely to be controlled by management to a much greater extent than is total SOM. Two field experiments, in south of Italy, were established in 2009 to study the changes in SOC during transition to organic farming. Experiments included a cereal/leguminous rotation with triplicates treatments of permitted amendments (compost and fertilizers). Soils were sampled at the beginning of the project, and after each crop harvest in 2010 and 2011. A sequential fractionation procedure was used to separate different SOC-fractions: light fraction (LF), two size classes of particulate organic matter (POM), mobile humic acid (MHA) and Ca++ bound humic acid (CaHA). Isolated fractions were quantified and analyzed for their content of C, N, carbohydrates and amino compounds fingerprints. The obtained results showed that compost application contributed to significantly higher quantities of LF, POM and MHA than did fertilizers application. Carbohydrates content decreased in LF while increased noticeably in POM and slightly in MHA fractions, which indicates that decomposing materials are converted, within the time span of humification, from young fractions into more mature fractions. Amino compounds were found to provide up to 40% of total soil N with a major contribution of the humified fractions, MHA and CaHA. The utilized

  9. Stepwise Rock-Eval pyrolysis as a tool for typing heterogeneous organic matter in soils

    Energy Technology Data Exchange (ETDEWEB)

    Hetenyi, M.; Nyilas, T.; Toth, T.M. [Department of Mineralogy, Geochemistry and Petrology, University of Szeged, P.O. Box 651, H-6701 Szeged (Hungary)

    2005-08-15

    This paper presents an application of Rock-Eval pyrolysis for estimating the proportion of the components with different thermal stability in soil organic matter, the maturity of which corresponds to the early stage of diagenesis. For testing the validity of the modified Rock-Eval method, parallel series of pyrolysis were carried out on sedimentary rock samples. The temperature program was selected on the basis of the results obtained from stepwise Rock-Eval pyrolysis and from the mathematical deconvolution of pyrograms. The proportion of the original biomolecules in soil organic matter was calculated by the integration of pyrograms below 350{sup o}C and could be determined rapidly by one single pyrolysis using 350{sup o}C as initial cracking temperature. At 380{sup o}C, both the mathematical and the experimental methods provide reliable information about the proportion of the humic substances. Conversely, for rock samples, mathematical deconvolution of the pyrograms showed the heterogeneity of the sedimentary organic matter, the maturity of which corresponds to late diagenesis, without any estimation of the proportion of the different components. The rate of organic carbon accumulation in the studied soils and the decomposition rate of biopolymers were interpreted as a function of land-use and redox conditions. Differences in the precursor vegetation and in the environmental parameters resulted in markedly reduced carbon storage and higher degree of humification in the agricultural soil than in the adjacent forest soil. Redox conditions strongly affected both the amount and the elemental composition of the stored organic matter. The decomposition rate of biopolymers appeared to be controlled mainly by the contribution of resistant lignin components to the source biomass and, to a lesser extent, by redox conditions.

  10. Physical disturbance to ecological niches created by soil structure alters community composition of methanotrophs.

    Science.gov (United States)

    Kumaresan, Deepak; Stralis-Pavese, Nancy; Abell, Guy C J; Bodrossy, Levente; Murrell, J Colin

    2011-10-01

    Aggregates of different sizes and stability in soil create a composite of ecological niches differing in terms of physico-chemical and structural characteristics. The aim of this study was to identify, using DNA-SIP and mRNA-based microarray analysis, whether shifts in activity and community composition of methanotrophs occur when ecological niches created by soil structure are physically perturbed. Landfill cover soil was subject to three treatments termed: 'control' (minimal structural disruption), 'sieved' (sieved soil using 2 mm mesh) and 'ground' (grinding using mortar and pestle). 'Sieved' and 'ground' soil treatments exhibited higher methane oxidation potentials compared with the 'control' soil treatment. Analysis of the active community composition revealed an effect of physical disruption on active methanotrophs. Type I methanotrophs were the most active methanotrophs in 'sieved' and 'ground' soil treatments, whereas both Type I and Type II methanotrophs were active in the 'control' soil treatment. The result emphasize that changes to a particular ecological niche may not result in an immediate change to the active bacterial composition and change in composition will depend on the ability of the bacterial communities to respond to the perturbation. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  11. Existing Versus Added Soil Organic Matter in Relation to Phosphorus Availability on Lateritic Soils

    Directory of Open Access Journals (Sweden)

    Fadly Hairannoor Yusran

    2008-01-01

    Full Text Available Lateritic soils (Ultisols and Oxisols are commonly characterised by high phosphate sorbing capacity due to the type of clay and present high content of aluminium (Al and iron (Fe oxides. Addition of fresh organic matter (OM may contribute to management of these soils by releasing more bicarbonate-extractable phosphorus (BP through organic phosphorus (OP transformation, or by the soluble component of OM additions desorbing phosphate by ligand exchange. It is not known, however, whether BP results solely from addition of new OM (by either mineralisation or desorption or from transformation of inherent or pre-existing in soil. We considered that removing the existing soil OM and replacing it with an equivalent amount of new OM may help to resolve this issue, especially with respect to P transformation after OM additions. Three lateritic soils of Western Australia (including a deep regolith material with very low inherent soil OM (SOM were used, and sub-samples of the three soils were combusted (450° C to obtain soils effectively free from existing OM. A further sub-sample of the soils was not combusted. Both soil groups, receiving the same amount of organic carbon (OC, from 80 ton ha-1 biomass + soil OM or biomass equal to soil OM from peat, wheat straw (Triticum aestivum L. and lucerne hay (Medicago sativa L., were incubated for nine months. Soil bicarbonate-extractable P as well as non-extractable P (NP, measured as Total-P (TP-BP increased due to new OM application in the order lucerne hay>peat>wheat straw. The correlation between BP with soil organic carbon (SOC became more positive over time. Microbial biomass phosphorus (MBP was not well correlated with the increase of NP content and phosphatase was not related to the increase in BP. Overall, freshly applied (new OM not only contributed to the increased level of P compared with the existing OM treatment.

  12. Worldwide organic soil carbon and nitrogen data

    Energy Technology Data Exchange (ETDEWEB)

    Zinke, P.J.; Stangenberger, A.G. [Univ. of California, Berkeley, CA (United States). Dept. of Forestry and Resource Management; Post, W.M.; Emanual, W.R.; Olson, J.S. [Oak Ridge National Lab., TN (United States)

    1986-09-01

    The objective of the research presented in this package was to identify data that could be used to estimate the size of the soil organic carbon pool under relatively undisturbed soil conditions. A subset of the data can be used to estimate amounts of soil carbon storage at equilibrium with natural soil-forming factors. The magnitude of soil properties so defined is a resulting nonequilibrium values for carbon storage. Variation in these values is due to differences in local and geographic soil-forming factors. Therefore, information is included on location, soil nitrogen content, climate, and vegetation along with carbon density and variation.

  13. Biochemical stability of organic matter in soils amended with organic slow N-release fertilizer derived from charred plant residues and ammonoxidized lignin

    Science.gov (United States)

    Knicker, Heike; de la Rosa, José Maria; López Martín, María; Clemente Barragan, Reyes; Liebner, Falk

    2013-04-01

    As an important plant nutrient, N that has been removed from the soil by plant growth is replaced mainly by the use of synthetic fertilizers. Although this practice has dramatically increased food production, the unintended costs to the environment and human health due to surplus and inefficient application have also been substantial. Major losses of N to the environment can be minimized if "sustainable" agricultural practices are combined with reasonable fertilization. The latter can be achieved by applying slow N-release fertilizers. Here, the N is incorporated into an organic matrix, which after its amendment to soils, slowly decompose, allowing the liberation of the nutrient. Deriving from organic waste, such an amendment helps to efficiently recycle resources and increases the C sequestration potential of soils. However, in order to turn this approach into a successful strategy, the material has to be bioavailable but still sufficiently recalcitrant to ensure slow and controlled N-release. In the present study, we tested potential slow N-release fertilizers recycled from organic waste for their biochemical stability in soils. They comprised N-rich charred grass residues and N-lignin derived from waste of the pulp and paper industry and enriched in N by ammonoxidation. The substrates were mixed with soil of an Histic Humaquept and subsequently subjected to microbial degradation at 28°C in a Respicond IV Apparatus for 10 weeks. Additionally, soil material without organic amendment and soils mixed with lignin or charcoal both with and without KNO3 were included into the experiment. During the degradation experiment the CO2 production was determined on an hourly base. The degradation rate constants and the mean residence times were calculated using a double exponential decay model (pools with fast and slow turnover). Alterations of the chemical composition of the organic matter during degradation were studied by solid-state 13C NMR spectroscopy. First results

  14. [Dynamics of unprotected soil organic carbon with the restoration process of Pinus massoniana plantation in red soil erosion area].

    Science.gov (United States)

    Lü, Mao-Kui; Xie, Jin-Sheng; Zhou, Yan-Xiang; Zeng, Hong-Da; Jiang, Jun; Chen, Xi-Xiang; Xu, Chao; Chen, Tan; Fu, Lin-Chi

    2014-01-01

    By the method of spatiotemporal substitution and taking the bare land and secondary forest as the control, we measured light fraction and particulate organic carbon in the topsoil under the Pinus massoniana woodlands of different ages with similar management histories in a red soil erosion area, to determine their dynamics and evaluate the conversion processes from unprotected to protected organic carbon. The results showed that the content and storage of soil organic carbon increased significantly along with ages in the process of vegetation restoration (P organic carbon content and distribution proportion to the total soil organic carbon increased significantly (P organic carbon mostly accumulated in the form of unprotected soil organic carbon during the initial restoration period, and reached a stable level after long-term vegetation restoration. Positive correlations were found between restoration years and the rate constant for C transferring from the unprotected to the protected soil pool (k) in 0-10 cm and 10-20 cm soil layers, which demonstrated that the unprotected soil organic carbon gradually transferred to the protected soil organic carbon in the process of vegetation restoration.

  15. Organic matter and soil moisture content and double cropping with organic matter sourceplants

    OpenAIRE

    John Bako Baon; Aris Wibawa

    2005-01-01

    Double cropping of coffee with organic matter source plants is thought to increase organic matter content of soil. This study examined the effect of double cropping of coffee and organic matter source plants on soil organic matter content and yield of coffee plants. Arabica coffee trees in Andungsari Experimental Station (Bondowoso district), 1400 m asl. and climate type C; and Robusta coffee trees in Sumberasin Experimental Station (Malang district), 550 m asl. and climate type C, were used ...

  16. [Composition and stability of soil aggregates in hedgerow-crop slope land].

    Science.gov (United States)

    Pu, Yu-Lin; Lin, Chao-Wen; Xie, De-Ti; Wei, Chao-Fu; Ni, Jiu-Pai

    2013-01-01

    Based on a long-term experiment of using hedgerow to control soil and water loss, this paper studied the composition and stability of soil aggregates in a hedgerow-crop slope land. Compared with those under routine contour cropping, the contents of > 0.25 mm soil mechanical-stable and water-stable aggregates under the complex mode hedgerow-crop increased significantly by 13.3%-16.1% and 37.8% -55.6%, respectively. Under the complex mode, the contents of > 0.25 mm soil water-stable aggregates on each slope position increased obviously, and the status of > 0.25 mm soil water-stable aggregates being relatively rich at low slope and poor at top slope was improved. Planting hedgerow could significantly increase the mean mass diameter and geometric mean diameter of soil aggregates, decrease the fractal dimension of soil aggregates and the destruction rate of > 0.25 mm soil aggregates, and thus, increase the stability and erosion-resistance of soil aggregates in slope cropland. No significant effects of slope and hedgerow types were observed on the composition, stability and distribution of soil aggregates.

  17. Effects of Spent Engine Oil Polluted Soil and Organic Amendment ...

    African Journals Online (AJOL)

    Effects of Spent Engine Oil Polluted Soil and Organic Amendment on Soil ... AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING AJOL ... of using organic fertilizer as bioremediant for spent engine oil polluted soils.

  18. Spectroscopic characteristics of soil organic matter as a tool to assess soil physical quality in Mediterranean ecosystems

    Science.gov (United States)

    Recio Vázquez, Lorena; Almendros, Gonzalo; Knicker, Heike; López-Martín, María; Carral, Pilar; Álvarez, Ana

    2014-05-01

    In Mediterranean areas, the loss of soil physical quality is of particular concern due to the vulnerability of these ecosystems in relation to unfavourable climatic conditions, which usually lead to soil degradation processes and severe decline of its functionality. As a result, increasing scientific attention is being paid on the exploration of soil properties which could be readily used as quality indicators, including organic matter which, in fact, represents a key factor in the maintenance of soil physical status. In this line, the present research tackles the assessment of the quality of several soils from central Spain with the purpose of identifying the physical properties most closely correlated with the organic matter, considering not only the quantity but also the quality of the different C-forms. The studied attributes consist of a series of physical properties determined in field and laboratory conditions-total porosity, aggregate stability, available water capacity, air provision, water infiltration rate and soil hydric saturation-.The bulk organic matter was characterised by solid-state 13C NMR spectroscopy and the major organic fractions (lipids, free particulate organic matter, fulvic acids, humic acids and humin) were quantified using standard procedures. The humic acids were also analysed by visible and infrared spectroscopies. The use of multidimensional scaling to classify physical properties in conjunction with molecular descriptors of soil organic matter, suggested significant correlations between the two set of variables, which were confirmed with simple and canonical regression models. The results pointed to two well-defined groups of physical attributes in the studied soils: (i) those associated with organic matter of predominantly aromatic character (water infiltration descriptors), and (ii) soil physical variables related to organic matter with marked aliphatic character, high preservation of the lignin signature and comparatively low

  19. Tree mycorrhizal type predicts within-site variability in the storage and distribution of soil organic matter.

    Science.gov (United States)

    Craig, Matthew E; Turner, Benjamin L; Liang, Chao; Clay, Keith; Johnson, Daniel J; Phillips, Richard P

    2018-03-24

    Forest soils store large amounts of carbon (C) and nitrogen (N), yet how predicted shifts in forest composition will impact long-term C and N persistence remains poorly understood. A recent hypothesis predicts that soils under trees associated with arbuscular mycorrhizas (AM) store less C than soils dominated by trees associated with ectomycorrhizas (ECM), due to slower decomposition in ECM-dominated forests. However, an incipient hypothesis predicts that systems with rapid decomposition-e.g. most AM-dominated forests-enhance soil organic matter (SOM) stabilization by accelerating the production of microbial residues. To address these contrasting predictions, we quantified soil C and N to 1 m depth across gradients of ECM-dominance in three temperate forests. By focusing on sites where AM- and ECM-plants co-occur, our analysis controls for climatic factors that covary with mycorrhizal dominance across broad scales. We found that while ECM stands contain more SOM in topsoil, AM stands contain more SOM when subsoil to 1 m depth is included. Biomarkers and soil fractionations reveal that these patterns are driven by an accumulation of microbial residues in AM-dominated soils. Collectively, our results support emerging theory on SOM formation, demonstrate the importance of subsurface soils in mediating plant effects on soil C and N, and indicate that shifts in the mycorrhizal composition of temperate forests may alter the stabilization of SOM. © 2018 John Wiley & Sons Ltd.

  20. SOMPROF: A vertically explicit soil organic matter model

    NARCIS (Netherlands)

    Braakhekke, M.C.; Beer, M.; Hoosbeek, M.R.; Kruijt, B.; Kabat, P.

    2011-01-01

    Most current soil organic matter (SOM) models represent the soil as a bulk without specification of the vertical distribution of SOM in the soil profile. However, the vertical SOM profile may be of great importance for soil carbon cycling, both on short (hours to years) time scale, due to

  1. Effects of Biochar Blends on Microbial Community Composition in Two Coastal Plain Soils

    Directory of Open Access Journals (Sweden)

    Thomas F. Ducey

    2015-11-01

    Full Text Available The amendment of soil with biochar has been demonstrated to have an effect not only on the soil physicochemical properties, but also on soil microbial community composition and activity. Previous reports have demonstrated significant impacts on soil microbial community structure. These impacts are modulated not only by the biochar composition, but also on the soil’s physicochemical characteristics. This indicates that soil characteristics must be considered prior to biochar amendment. A significant portion of the soils of the southeastern coastal plain are severely degraded and, therefore, candidates for biochar amendment to strengthen soil fertility. In this study we focused on two common soil series in the southeastern coastal plain, utilizing feedstocks endemic to the area. We chose feedstocks in four ratios (100% pine chip; 80:20 mixture of pine chip to poultry litter; 50:50 mixture of pine chip to poultry litter; 100% poultry litter prior to pyrolysis and soil amendment as a biochar product. Soil was analyzed for bioavailable nutrients via Mehlich-1 extractions, as well as microbial community composition using phospholipid fatty acid analysis (PLFA. Our results demonstrated significant shifts in microbial community composition in response to biochar amendment, the effects of which were greatest with 100% poultry litter biochar. Strong relationships between PLFAs and several Mehlich-1 extractable nutrients (Al, Cu, Fe, and P were observed.

  2. Assessment of Soil Health in Urban Agriculture: Soil Enzymes and Microbial Properties

    Directory of Open Access Journals (Sweden)

    Avanthi Deshani Igalavithana

    2017-02-01

    Full Text Available Urban agriculture has been recently highlighted with the increased importance for recreation in modern society; however, soil quality and public health may not be guaranteed because of continuous exposure to various pollutants. The objective of this study was to evaluate the soil quality of urban agriculture by soil microbial assessments. Two independent variables, organic and inorganic fertilizers, were considered. The activities of soil enzymes including dehydrogenase, β-glucosidase, arylsulfatase, urease, alkaline and acid phosphatases were used as indicators of important microbial mediated functions and the soil chemical properties were measured in the soils applied with organic or inorganic fertilizer for 10 years. Fatty acid methyl ester analysis was applied to determine the soil microbial community composition. Relatively higher microbial community richness and enzyme activities were found in the organic fertilizers applied soils as compared to the inorganic fertilizers applied soils. Principal component analysis explained the positive influence of organic fertilizers on the microbial community. The application of organic fertilizers can be a better alternative compared to inorganic fertilizers for the long-term health and security of urban agriculture.

  3. Similar processes but different environmental filters for soil bacterial and fungal community composition turnover on a broad spatial scale.

    Science.gov (United States)

    Chemidlin Prévost-Bouré, Nicolas; Dequiedt, Samuel; Thioulouse, Jean; Lelièvre, Mélanie; Saby, Nicolas P A; Jolivet, Claudy; Arrouays, Dominique; Plassart, Pierre; Lemanceau, Philippe; Ranjard, Lionel

    2014-01-01

    Spatial scaling of microorganisms has been demonstrated over the last decade. However, the processes and environmental filters shaping soil microbial community structure on a broad spatial scale still need to be refined and ranked. Here, we compared bacterial and fungal community composition turnovers through a biogeographical approach on the same soil sampling design at a broad spatial scale (area range: 13300 to 31000 km2): i) to examine their spatial structuring; ii) to investigate the relative importance of environmental selection and spatial autocorrelation in determining their community composition turnover; and iii) to identify and rank the relevant environmental filters and scales involved in their spatial variations. Molecular fingerprinting of soil bacterial and fungal communities was performed on 413 soils from four French regions of contrasting environmental heterogeneity (Landescommunities' composition turnovers. The relative importance of processes and filters was assessed by distance-based redundancy analysis. This study demonstrates significant community composition turnover rates for soil bacteria and fungi, which were dependent on the region. Bacterial and fungal community composition turnovers were mainly driven by environmental selection explaining from 10% to 20% of community composition variations, but spatial variables also explained 3% to 9% of total variance. These variables highlighted significant spatial autocorrelation of both communities unexplained by the environmental variables measured and could partly be explained by dispersal limitations. Although the identified filters and their hierarchy were dependent on the region and organism, selection was systematically based on a common group of environmental variables: pH, trophic resources, texture and land use. Spatial autocorrelation was also important at coarse (80 to 120 km radius) and/or medium (40 to 65 km radius) spatial scales, suggesting dispersal limitations at these scales.

  4. Speciation of organic matter in sandy soil size fractions as revealed by analytical pyrolysis (Py-GC/MS) and FT-IR spectroscopy

    Science.gov (United States)

    Jiménez-Morillo, Nicasio T.; González-Vila, Francisco J.; Jordán, Antonio; Zavala, Lorena M.; de la Rosa, José M.; González-Pérez, José A.

    2015-04-01

    This research deals with the assessment of organic matter structural differences in soil physical fractions before and after lipid extractions. Soil samples were collected in sandy soils, Arenosols (WRB 2006) from the Doñana National Park (SW Spain) under different vegetation cover: cork oak (Quercus suber, QS), eagle fern (Pteridium aquilinum, PA), pine (Pinus pinea, PP) and rockrose (Halimium halimifolium, HH). Two size fractions; coarse (C: 1-2 mm) and fine (F: 0.05-0.25 mm) were studied from each soil. . In addition, the two fractions from each soil were exhaustively Soxhlet extracted with a Dichlorometane-Methanol (3:1) mixture to obtain the lipid-free fractions (LF) from each size fraction (LFC and LFF). The composition of the organic matter at a molecular level in the different soil fractions was approached by analytical pyrolysis (Py-GC/MS) and FT-IR spectroscopy. These techniques are complementary and have been found suitable for the structural characterization of complex organic matrices (Moldoveanu, 1998; Piccolo and Stevenson, 1982); whereas Py-GC/MS provides detailed structural information of individual compounds present and a finger-printing of soil organic matter, FT-IR is informative about major functional groups present. The advantages of these techniques are well known: no need for pretreatment are fast to perform, highly reproducible and only small amount of samples are needed. Soil size fractions show contrasting differences in organic matter content (C 4-7 % and F > 40 %) and conspicuous differences were found in the pyrolysis products released by the fractions studied. The main families of pyrolysis compounds have well defined macromolecular precursors, such as lignin, polypeptides, polysaccharides and lipids (González-Vila et al., 2001). The C fractions yield higher relative abundance of lignin and polysaccharide derived pyrolysis compounds. Regarding the differences in the soil organic matter as affected by the different vegetation covers

  5. Soil organic matter degradation and enzymatic profiles of intertidal and subaqueous soils

    Science.gov (United States)

    Ferronato, Chiara; Marinari, Sara; Bello, Diana; Vianello, Gilmo; Trasar-Cepeda, Carmen; Vittori Antisari, Livia

    2017-04-01

    The interest on intertidal and subaqueous soils has recently arisen because of the climate changes forecasts. The preservation of these habitats represents an important challenge for the future of humanity, because these systems represent an important global C sink since soil organic matter (SOM) on intertidal and subaqueous soils undergoes very slow degradation rates due to oxygen limitation. Publications on SOM cycle in saltmarshes are very scarce because of the difficulties involved on those studies i.e. the interaction of many abiotic and biotic factors (e.g., redox changes, water and bio-turbation processes, etc) and stressors (e.g., salinity and anoxia). However, saltmarshes constitute an unique natural system to observe the influence of anoxic conditions on SOM degradation, because the tide fluctuations on the soil surface allow the formation of provisionally or permanently submerged soils. With the aim to investigate the quality of SOM in subaqueous soils, triplicates of subaqueous soils (SASs), intertidal soils (ITSs) and terrestrial soils (TESs) were collected in the saltmarshes of the Baiona Lagoon (Northern Italy) and classified according to their pedogenetic horizons. The SOM quality on each soil horizon was investigated by quantifying SOM, total and water-soluble organic carbon (TOC, WSC) and microbial biomass carbon (MBC). Given the contribution of soil enzymes to the degradation of SOM, some enzymatic assays were also performed. Thereafter, soil classification and humus morpho-functional classification were used to join together similar soil profiles to facilitate the description and discussion of results. Soils were ranked as Aquent or Wassent Entisols, with an A/AC/C pedosequence. SOM, TOC and MBC were statistically higher in A than in AC and C horizons. Among the A horizons, ITSs were those showing the highest values for these parameters (11% TOC, 1.6 mg kg-1 MBC, 0.9 mg kg-1 WSC). These results, combined with the morpho-functional classification

  6. Organic Matter Dynamics in Soils Regenerating from Degraded ...

    African Journals Online (AJOL)

    The area of secondary forest (SF) regenerating from degraded abandoned rubber (Hevea brasiliensis) plantation is increasing in the rainforest zone of south southern Nigeria; however, the build-up of soil organic matter following abandonment is not well understood. This study examined the build-up of soil organic matter in ...

  7. Plant community and litter composition in temperate deciduous woodlots along two field gradients of soil Ni, Cu and Co concentrations

    International Nuclear Information System (INIS)

    Hale, Beverley; Robertson, Paul

    2016-01-01

    Perennial plant communities in the proximity of metal smelters and refineries may receive substantial inputs of base metal particulate as well as sulphate from the co-emission of sulphur dioxide. The Ni refinery at Port Colborne (Canada) operated by Inco (now Vale Canada Ltd.) emitted Ni, Co and Cu, along with sulphur dioxide, between 1918 and 1984. The objectives were to determine if vascular plant community composition, including standing litter, in twenty-one woodlots on clay or organic soil, were related to soil Ni concentration which decreased in concentration with distance from the Ni refinery. The soil Ni concentration in the clay woodlots ranged from 16 to 4130 mg Ni/kg, and in the organic woodlots, ranged from 98 to 22,700 mg Ni/kg. The concentrations of Co and Cu in the soils were also elevated, and highly correlated with soil Ni concentration. In consequence, each series of woodlots constituted a ‘fixed ratio ray’ of metal mixture exposure. For each of the woodlots, there were 16 independent measurements of ‘woodlot status’ which were correlated with elevated soil Ni concentration. Of the 32 combinations, there were eight linear correlations with soil Ni concentration, considerably more than would be expected by chance alone at a p-value of 0.05. With the exception of mean crown rating for shrubs at the clay sites, the correlations were consistent with the hypothesis that increased soil metal concentrations would be correlated with decreased diversity, plant community health or fitness, and increased accumulation of litter. Only five of the eight linear correlations were from the organic woodlots, suggesting that the observations were not confounded with soil type nor range in soil metal concentrations. - Highlights: • Temperate woodlots on organic or clay soils with gradient of soil Ni were studied. • Soil Ni ranged up to 4100 mg/kg on clay and up to 22,700 mg/kg on organic. • Most indices of plant community status were not correlated

  8. Organic matter and soil structure in the Everglades Agricultural Area

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Alan L. [Univ. of Florida, Gainesville, FL (United States); Hanlon, Edward A. [Univ. of Florida, Gainesville, FL (United States)

    2013-01-01

    This publication pertains to management of organic soils (Histosols) in the Everglades Agricultural Area (EAA). These former wetland soils are a major resource for efficient agricultural production and are important globally for their high organic matter content. Recognition of global warming has led to considerable interest in soils as a repository for carbon. Soils rich in organic matter essentially sequester or retain carbon in the profile and can contribute directly to keeping that sequestered carbon from entering the atmosphere. Identification and utilization of management practices that minimize the loss of carbon from organic soils to the atmosphere can minimize effects on global warming and increase the longevity of subsiding Histosols for agricultural use. Understanding and predicting how these muck soils will respond to current and changing land uses will help to manage soil carbon. The objectives of this document are to: a. Discuss organic soil oxidation relative to storing or releasing carbon and nitrogen b. Evaluate effects of cultivation (compare structure for sugarcane vs. uncultivated soil) Based upon the findings from the land-use comparison (sugarcane or uncultivated), organic carbon was higher with cultivation in the lower depths. There is considerable potential for minimum tillage and residue management to further enhance carbon sequestration in the sugarcane system. Carbon sequestration is improved and soil subsidence is slowed with sugarcane production, and both of these are positive outcomes. Taking action to increase or maintain carbon sequestration appears to be appropriate but may introduce some risk to farming operations. Additional management methods are needed to reduce this risk. For both the longevity of these organic soils and from a global perspective, slowing subsidence through BMP implementation makes sense. Since these BMPs also have considerable societal benefit, it remains to be seen if society will help to offset a part or all

  9. LOSS OF ORGANIC CHEMICALS IN SOIL: PURE COMPOUND TREATABILITY STUDIES

    Science.gov (United States)

    Comprehensive screening data on the treatability of 32 organic chemicals in soil were developed. Of the evaluated chemicals, 22 were phenolic compounds. Aerobic batch laboratory microcosm experiments were conducted using two soils: an acidic clay soil with <1% organic matter and ...

  10. Organic Matter Stocks and the Interactions of Humic Substances with Metals in Araucaria Moist Forest Soil with Humic and Histic Horizons

    Directory of Open Access Journals (Sweden)

    Daniel Hanke

    Full Text Available ABSTRACT Soils with humic and histic horizons in tropical and subtropical ecosystems play an important role in determining the atmospheric C stock and its stabilization, climate regulation, water holding capacity, and environmental filtering, due to the different functions of soil organic matter (SOM. However, the processes and mechanisms that regulate SOM dynamics in these soils are not clear. The objectives of this study were: i determine the C and N stocks and ii investigate the SOM chemical fractions and their interactions with Fe and Al ions in soils with humic and histic horizons of a toposequence under Araucaria moist forest in southern Brazil. The soils sampled were classified as Humic Hapludox (top - not hydromorphic, Fluvaquentic Humaquepts (lower third - hydromorphic, and Typic Haplosaprists (floodplain - hydromorphic. The C and N contents were determined in bulk soil samples and SOM chemical fractions; in these fractions, Fe and Al co-extracted contents were also determined. The chemical composition of humin and humic acid fractions was investigated by FTIR spectroscopy. The C content in the toposequence increased from the top to the lowest position. The differences observed in SOM content and SOM chemical composition were defined by the differences in soil water regime. The amount of C stored in the subsurface horizons is about 70 % of total organic C. The carbohydrate-like structures in the humin fraction were protected from solubilization through interaction with iron oxides, which may represent an important mechanism for labile organic compound preservation in these soils. The soluble humic substances showed the highest Fe and Al contents, and their compartments have different affinities for Fe and Al.

  11. Soil organic matter dynamics in a North America tallgrass prairie after 9 yr of experimental warming

    Directory of Open Access Journals (Sweden)

    X. Cheng

    2011-06-01

    Full Text Available The influence of global warming on soil organic matter (SOM dynamics in terrestrial ecosystems remains unclear. In this study, we combined soil fractionation with isotope analyses to examine SOM dynamics after nine years of experimental warming in a North America tallgrass prairie. Soil samples from the control plots and the warmed plots were separated into four aggregate sizes (>2000 μm, 250–2000 μm, 53–250 μm, and <53 μm, and three density fractions (free light fraction – LF, intra-aggregate particulate organic matter – iPOM, and mineral-associated organic matter – mSOM. All fractions were analyzed for their carbon (C and nitrogen (N content, and δ13C and δ15N values. Warming did not significantly effect soil aggregate distribution and stability but increased C4-derived C input into all fractions with the greatest in LF. Warming also stimulated decay rates of C in whole soil and all aggregate sizes. C in LF turned over faster than that in iPOM in the warmed soils. The δ15N values of soil fractions were more enriched in the warmed soils than those in the control, indicating that warming accelerated loss of soil N. The δ15N values changed from low to high, while C:N ratios changed from high to low in the order LF, iPOM, and mSOM due to increased degree of decomposition and mineral association. Overall, warming increased the input of C4-derived C by 11.6 %, which was offset by the accelerated loss of soil C. Our results suggest that global warming simultaneously stimulates C input via shift in species composition and decomposition of SOM, resulting in negligible net change in soil C.

  12. Comparative effects of organic compost and NPK fertilizer on soil ...

    African Journals Online (AJOL)

    Pre-treatment and post planting soil samples were taken for laboratory soil analysis of soil chemical properties for a comparison of the assessment of the cumulative effects of organic compost and inorganic fertilizer in improving soil fertility over a period of three years. The organic matter increased by 23.3% and 0.6% in the ...

  13. Soil mineral composition matters: response of microbial communities to phenanthrene and plant litter addition in long-term matured artificial soils.

    Science.gov (United States)

    Babin, Doreen; Vogel, Cordula; Zühlke, Sebastian; Schloter, Michael; Pronk, Geertje Johanna; Heister, Katja; Spiteller, Michael; Kögel-Knabner, Ingrid; Smalla, Kornelia

    2014-01-01

    The fate of polycyclic aromatic hydrocarbons (PAHs) in soil is determined by a suite of biotic and abiotic factors, and disentangling their role in the complex soil interaction network remains challenging. Here, we investigate the influence of soil composition on the microbial community structure and its response to the spiked model PAH compound phenanthrene and plant litter. We used long-term matured artificial soils differing in type of clay mineral (illite, montmorillonite) and presence of charcoal or ferrihydrite. The soils received an identical soil microbial fraction and were incubated for more than two years with two sterile manure additions. The matured artificial soils and a natural soil were subjected to the following spiking treatments: (I) phenanthrene, (II) litter, (III) litter + phenanthrene, (IV) unspiked control. Total community DNA was extracted from soil sampled on the day of spiking, 7, 21, and 63 days after spiking. Bacterial 16S rRNA gene and fungal internal transcribed spacer amplicons were quantified by qPCR and subjected to denaturing gradient gel electrophoresis (DGGE). DGGE analysis revealed that the bacterial community composition, which was strongly shaped by clay minerals after more than two years of incubation, changed in response to spiked phenanthrene and added litter. DGGE and qPCR showed that soil composition significantly influenced the microbial response to spiking. While fungal communities responded only in presence of litter to phenanthrene spiking, the response of the bacterial communities to phenanthrene was less pronounced when litter was present. Interestingly, microbial communities in all artificial soils were more strongly affected by spiking than in the natural soil, which might indicate the importance of higher microbial diversity to compensate perturbations. This study showed the influence of soil composition on the microbiota and their response to phenanthrene and litter, which may increase our understanding of

  14. The Role of Physical and Human Landscape Properties on Carbon Composition of Organic Matter in Tropical Rivers

    Science.gov (United States)

    Ballester, M. R.; Krusche, A. V.; Victoria, R. L.; Richey, J. E.; Deegan, L.; Neill, C.

    2011-12-01

    To evaluate physical and human controls organic matter carbon composition in tropical rivers, we applied an integrated analysis of landscape properties and riverine isotopic composition. Our goal was to establish the relationships between basin attributes and forms and composition of dissolved and particulate organic matter in rivers. A GIS template was developed as tool to support the understanding of the biogeochemistry of the surface waters of the Ji-Paraná (Western Amazonia) and the Piracicaba (southeastern of Brazil)rivers. Each basin was divided into drainage units, organized according to river network morphology and degree of land-use impact. The delineated drainage areas were individually characterized in terms of topography, soils and land use using data sets compiled as layers in ArcGis and ERDAS-IMAGINE software. DOM and POM carbon stable isotopic composition were determined at several sites along the main tributaries and small streams. The effects of these drivers on the fluvial carbon was quantified by a multiple linear regression analysis, relating basin characteristics and river isotopic composition. The results showed that relatively recent land cover changes have already had an impact on the composition of the riverine DOM and POM, indicating that, as in natural ecosystems, the vegetation plays a key role in the composition of the riverine organic matter in agricultural systems.

  15. SOIL ORGANIC CARBON LEVELS IN SOILS OF CONTRASTING LAND USES IN SOUTHEASTERN NIGERIA

    Directory of Open Access Journals (Sweden)

    Chinyere Blessing Okebalama

    2017-12-01

    Full Text Available Land use change affects soil organic carbon (SOC storage in tropical soils, but information on the influence of land use change on segmental topsoil organic carbon stock is lacking. The study investigated SOC levels in Awgu (L, Okigwe (CL, Nsukka I (SL, and Nsukka II (SCL locations in southeastern Nigeria. Land uses considered in each location were the cultivated (manually-tilled and the adjacent uncultivated (4-5 year bush-fallow soils from which samples at 0-10, 10-20, and 20-30 cm topsoil depth were assessed. The SOC level decreased with topsoil depth in both land uses. Overall, the SOC level at 0-30 cm was between 285.44 and 805.05 Mg ha-1 amongst the soils.  The uncultivated sites stored more SOC than its adjacent cultivated counterpart at 0-10 and 10-20 cm depth, except in Nsukka II soils, which had significantly higher SOC levels in the cultivated than the uncultivated site. Nonetheless, at 20-30 cm depth, the SOC pool across the fallowed soils was statistically similar when parts of the same soil utilization type were tilled and cultivated. Therefore, while 4 to 5 years fallow may be a useful strategy for SOC stabilization within 20-30 cm topsoil depth in the geographical domain, segmental computation of topsoil organic carbon pool is critical.

  16. Soils of postpyrogenic larch stands in Central Siberia: Morphology, physicochemical properties, and specificity of soil organic matter

    Science.gov (United States)

    Startsev, V. V.; Dymov, A. A.; Prokushkin, A. S.

    2017-08-01

    Morphological features, physicochemical properties, and specific characteristics of the organic matter of cryozems (Cryosols) under postpyrogenic larch forests affected by fires 2, 6, 22, 55, and 116 years ago are considered. The morphological changes in the soils affected by fires are manifested by the burning of the upper organic horizons with preservation of pyrogenic features in the soils for more than a century after the fire. In the first years (2 and 6 years) after the fire, the acidity of the organic horizons and their base saturation become lower. The postpyrogenic soils are characterized by the smaller contribution of the organic horizons to the total pools of soil organic carbon. In the studied cryozems, the organic carbon content is correlated with the contents of oxalate-extractable iron and aluminum. A decrease in the content of water-soluble organic compounds in the soils is observed after the fires; gradually, their content increases upon restoration of the ground cover.

  17. Use of stable isotope techniques in soil organic matter studies

    International Nuclear Information System (INIS)

    Gerzabek, M.H.

    1998-01-01

    Plants differ distinctly in their C-isotopic composition. The largest differences occur between plant species with different photosynthetic pathways. C 3 - and C 4 -plants are differentiated by approximately 1.4% on the δ-scale (approx. -2.7% 13 C versus -1.3% 13 C). Modern elemental analyser - mass spectrometer combinations reach accuracies of at least 0.01% δ 13 C. Therefore, the difference between C 3 and C 4 plants is sufficient to be used for tracer studies. Several investigations of soil organic mater (SOM) turnover under field conditions were undertaken using the fact that the vegetation cover changed between C 3 and C 4 plants. The discrimination between SOM originating from indigenous vegetation (forest, C 3 ) and sugar cane (C 4 ) after 50 years of cropping introducing two SOM compartments of different stability was described. Another example is the change from prairie vegetation (C 4 ) to different C 3 -crops and the evaluation of the carbon origin at or near equilibrium. More recent studies use 15 N-labelled C 4 -plant residues or 13 C-labelled C 3 -plants to elucidate the fate of carbon and nitrogen in soils developed under C 3 -vegetation. Both in situ experiments and laboratory incubations were used to evaluate carbon and nitrogen fluxes from crop residues. Physical fractionation of bulk soil into particle sizes proved to be of advantage to follow short and long-term dynamics of crop residues within SOM. Changes in the natural abundance of 13 C and 15 N within soil profiles can elucidate leaching or mineralization of humic substances. Changes in the natural abundance of stable isotopes are also possible due to the application of organic manures, quantification, however is not easy because of the small isotopic differences between soil and manure carbon and nitrogen. 15 N labelling of soil nitrogen has been widely used in the last two decades to quantify biological nitrogen fixation. Considerable progress has been made due to the isotope dilution

  18. ON THE DIVISION OF NORTH BOUNDARY OF SUBTROPICAL ZONE ACCORDING TO THE COMPOSITIONS AND PROPERTIES OF SOIL HUMUS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In this paper predecessors′ achievements about the division between subtropical zone and warm temperate zone on the south slope of Funiu Mountain are firstly summarized, and the cause why these viewpoints about the division are different also has been presented. Seven soil profiles at different heights above sea level are dug along the south slope of Funiu Mountain. Many compositions and properties of soil humus have been analyzed in laboratory. A comprehensive study has been made about the division according to the compositions and properties of soil humus with mathematical method. During the analysis process eight indexes have been used, such as altitude, organic carbon, humic acid (HA), fulvic acid (FA), the ratio of humic acid and fulvic acid (HA/FA), two extinction coefficients (E4,E6), and their ratio (E4/E6).The result indicates that the boundary is at about 1000 meters above sea level.

  19. ON THE DIVISION OF NORTH BOUNDARY OF SUBTROPICAL ZONE ACCORDING TO THE COMPOSITIONS AND PROPERTIES OF SOIL HUMUS

    Institute of Scientific and Technical Information of China (English)

    MAJian-hua; ZHAOQing-liang; 等

    2002-01-01

    In this paper predecessorsˊ achievements about the division between subtropical zone and warm temperate zone on the south slope of Funiu Mountain are firstly summarized,and the cause why these viewpoints about the division are different also has been presented.Seven soil profiles at different heights above sea level are dug along the south slope of Funiu Mountain.Many compositions and properties of soil humus have been analyzed in laboratory.A comprehensive study has been made about the division according to the compositions and properties of soil humus with mathematical method.During the analysis process eitht indexes have been used,such as altitude,organic carbon,humic acid(HA),fulvic acid(FA),the ratio of humic acid and fulvic acid(HA/FA),two extinction coefficients(E4,E6), and their ratio (E4/E6).The result indicates that the boundary is at about 1000 meters above sea level.

  20. Composition of soil microbiome along elevation gradients in southwestern highlands of Saudi Arabia.

    Science.gov (United States)

    Yasir, Muhammad; Azhar, Esam I; Khan, Imran; Bibi, Fehmida; Baabdullah, Rnda; Al-Zahrani, Ibrahim A; Al-Ghamdi, Ahmed K

    2015-03-14

    Saudi Arabia is mostly barren except the southwestern highlands that are susceptible to environmental changes, a hotspot for biodiversity, but poorly studied for microbial diversity and composition. In this study, 454-pyrosequencing of 16S rRNA gene hypervariable region V6 was used to analyze soil bacterial community along elevation gradients of the southwestern highlands. In general, lower percentage of total soil organic matter (SOM) and nitrogen were detected in the analyzed soil samples. Total 33 different phyla were identified across the samples, including dominant phyla Proteobacteria, Actinobacteria and Acidobacteria. Representative OTUs were grouped into 329 and 508 different taxa at family and genus level taxonomic classification, respectively. The identified OTUs unique to each sample were very low irrespective of the altitude. Jackknifed principal coordinates analysis (PCoA) revealed, overall differences in the bacterial community were more related to the quantity of specific OTUs than to their diversity among the studied samples. Bacterial diversity and soil physicochemical properties did not show consistent changes along the elevation gradients. The large number of OTUs shared between the studied samples suggest the presence of a core soil bacterial community in the southwestern highlands of Saudi Arabia.

  1. Composite Sampling Approaches for Bacillus anthracis Surrogate Extracted from Soil.

    Directory of Open Access Journals (Sweden)

    Brian France

    Full Text Available Any release of anthrax spores in the U.S. would require action to decontaminate the site and restore its use and operations as rapidly as possible. The remediation activity would require environmental sampling, both initially to determine the extent of contamination (hazard mapping and post-decon to determine that the site is free of contamination (clearance sampling. Whether the spore contamination is within a building or outdoors, collecting and analyzing what could be thousands of samples can become the factor that limits the pace of restoring operations. To address this sampling and analysis bottleneck and decrease the time needed to recover from an anthrax contamination event, this study investigates the use of composite sampling. Pooling or compositing of samples is an established technique to reduce the number of analyses required, and its use for anthrax spore sampling has recently been investigated. However, use of composite sampling in an anthrax spore remediation event will require well-documented and accepted methods. In particular, previous composite sampling studies have focused on sampling from hard surfaces; data on soil sampling are required to extend the procedure to outdoor use. Further, we must consider whether combining liquid samples, thus increasing the volume, lowers the sensitivity of detection and produces false negatives. In this study, methods to composite bacterial spore samples from soil are demonstrated. B. subtilis spore suspensions were used as a surrogate for anthrax spores. Two soils (Arizona Test Dust and sterilized potting soil were contaminated and spore recovery with composites was shown to match individual sample performance. Results show that dilution can be overcome by concentrating bacterial spores using standard filtration methods. This study shows that composite sampling can be a viable method of pooling samples to reduce the number of analysis that must be performed during anthrax spore remediation.

  2. Predicting long-term organic carbon dynamics in organically amended soils using the CQESTR model

    Energy Technology Data Exchange (ETDEWEB)

    Plaza, Cesar; Polo, Alfredo [Consejo Superior de Investigaciones Cientificas, Madrid (Spain). Inst. de Ciencias Agrarias; Gollany, Hero T. [Columbia Plateau Conservation Research Center, Pendleton, OR (United States). USDA-ARS; Baldoni, Guido; Ciavatta, Claudio [Bologna Univ. (Italy). Dept. of Agroenvironmental Sciences and Technologies

    2012-04-15

    Purpose: The CQESTR model is a process-based C model recently developed to simulate soil organic matter (SOM) dynamics and uses readily available or easily measurable input parameters. The current version of CQESTR (v. 2.0) has been validated successfully with a number of datasets from agricultural sites in North America but still needs to be tested in other geographic areas and soil types under diverse organic management systems. Materials and methods: We evaluated the predictive performance of CQESTR to simulate long-term (34 years) soil organic C (SOC) changes in a SOM-depleted European soil either unamended or amended with solid manure, liquid manure, or crop residue. Results and discussion: Measured SOC levels declined over the study period in the unamended soil, remained constant in the soil amended with crop residues, and tended to increase in the soils amended with manure, especially with solid manure. Linear regression analysis of measured SOC contents and CQESTR predictions resulted in a correlation coefficient of 0.626 (P < 0.001) and a slope and an intercept not significantly different from 1 and 0, respectively (95% confidence level). The mean squared deviation and root mean square error were relatively small. Simulated values fell within the 95% confidence interval of the measured SOC, and predicted errors were mainly associated with data scattering. Conclusions: The CQESTR model was shown to predict, with a reasonable degree of accuracy, the organic C dynamics in the soils examined. The CQESTR performance, however, could be improved by adding an additional parameter to differentiate between pre-decomposed organic amendments with varying degrees of stability. (orig.)

  3. Cost effective tools for soil organic carbon monitoring

    Science.gov (United States)

    Shepherd, Keith; Aynekulu, Ermias

    2013-04-01

    There is increasing demand for data on soil properties at fine spatial resolution to support management and planning decisions. Measurement of soil organic carbon has attracted much interest because (i) soil organic carbon is widely cited as a useful indicator of soil condition and (ii) of the importance of soil carbon in the global carbon cycle and climate mitigation strategies. However in considering soil measurement designs there has been insufficient attention given to careful analysis of the specific decisions that the measurements are meant to support and on what measurements have high information value for decision-making. As a result, much measurement effort may be wasted or focused on the wrong variables. A cost-effective measurement is one that reduces risk in decisions and does not cost more than the societal returns to additional evidence. A key uncertainty in measuring soil carbon as a soil condition indicator is what constitutes a good or bad level of carbon on a given soil. A measure of soil organic carbon concentration may have limited value for informing management decisions without the additional information required to interpret it, and so expending further efforts on improving measurements to increase precision may then have no value to improving the decision. Measuring soil carbon stock changes for carbon trading purposes requires high levels of measurement precision but there is still large uncertainty on whether the costs of measurement exceed the benefits. Since the largest cost component in soil monitoring is often travel to the field and physically sampling soils, it is generally cost-effective to meet multiple objectives by analysing a number of properties on a soil sample. Diffuse reflectance infrared spectroscopy is playing a key role in allowing multiple soil properties to be determined rapidly and at low cost. The method provides estimation of multiple soil properties (e.g. soil carbon, texture and mineralogy) in one measurement

  4. Migration through soil of organic solutes in an oil-shale process water

    Science.gov (United States)

    Leenheer, J.A.; Stuber, H.A.

    1981-01-01

    The migration through soil of organic solutes in an oil-shale process water (retort water) was studied by using soil columns and analyzing leachates for various organic constituents. Retort water extracted significant quantities of organic anions leached from ammonium-saturated-soil organic matter, and a distilled-water rinse, which followed retort-water leaching, released additional organic acids from the soil. After being corrected for organic constitutents extracted from soil by retort water, dissolved-organic-carbon fractionation analyses of effluent fractions showed that the order of increasing affinity of six organic compound classes for the soil was as follows: hydrophilic neutrals nearly equal to hydrophilic acids, followed by the sequence of hydrophobic acids, hydrophilic bases, hydrophobic bases, and hydrophobic neutrals. Liquid-chromatographic analysis of the aromatic amines in the hydrophobic- and hydrophilic-base fractions showed that the relative order of the rates of migration through the soil column was the same as the order of migration on a reversed-phase, octadecylsilica liquid-chromatographic column.

  5. Long-term litter manipulation alters soil organic matter turnover in a temperate deciduous forest.

    Science.gov (United States)

    Wang, Jun-Jian; Pisani, Oliva; Lin, Lisa H; Lun, Olivia O Y; Bowden, Richard D; Lajtha, Kate; Simpson, André J; Simpson, Myrna J

    2017-12-31

    Understanding soil organic matter (OM) biogeochemistry at the molecular-level is essential for assessing potential impacts from management practices and climate change on shifts in soil carbon storage. Biomarker analyses and nuclear magnetic resonance (NMR) spectroscopy were used in an ongoing detrital input and removal treatment experiment in a temperate deciduous forest in Pennsylvania, USA, to examine how above- and below-ground plant inputs control soil OM quantity and quality at the molecular-level. From plant material to surface soils, the free acyclic lipids and cutin, suberin, and lignin biomarkers were preferentially retained over free sugars and free cyclic lipids. After 20years of above-ground litter addition (Double Litter) or exclusion (No Litter) treatments, soil OM composition was relatively more degraded, as revealed by solid-state 13 C NMR spectroscopy. Under Doubled Litter inputs, soil carbon and phospholipid fatty acid (PLFA) concentrations were unchanged, suggesting that the current OM degradation status is a reflection of microbial-mediated degradation that occurred prior to the 20-year sampling campaign. Soil OM degradation was higher in the No Litter treatments, likely due to the decline in fresh, above-ground litter inputs over time. Furthermore, root and root and litter exclusion treatments (No Roots and No Inputs, respectively) both significantly reduced free sugars and PLFAs and increased preservation of suberin-derived compounds. PLFA stress ratios and the low N-acetyl resonances from diffusion edited 1 H NMR also indicate substrate limitations and reduced microbial biomass with these treatments. Overall, we highlight that storage of soil carbon and its biochemical composition do not linearly increase with plant inputs because the microbial processing of soil OM is also likely altered in the studied forest. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Microbial interactions with organic contaminants in soil: Definitions, processes and measurement

    International Nuclear Information System (INIS)

    Semple, Kirk T.; Doick, Kieron J.; Wick, Lukas Y.; Harms, Hauke

    2007-01-01

    There has been and continues to be considerable scientific interest in predicting bioremediation rates and endpoints. This requires the development of chemical techniques capable of reliably predicting the bioavailability of organic compounds to catabolically active soil microbes. A major issue in understanding the link between chemical extraction and bioavailability is the problem of definition; there are numerous definitions, of varying degrees of complexity and relevance, to the interaction between organic contaminants and microorganisms in soil. The aim of this review is to consider the bioavailability as a descriptor for the rate and extent of biodegradation and, in an applied sense, bioremediation of organic contaminants in soil. To address this, the review will (i) consider and clarify the numerous definitions of bioavailability and discuss the usefulness of the term 'bioaccessibility'; (ii) relate definition to the microbiological and chemical measurement of organic contaminants' bioavailability in soil, and (iii) explore the mechanisms employed by soil microorganisms to attack organic contaminants in soil. - Understanding organic contaminant's behaviour in soil is key to chemically predicting biodegradation

  7. Process based modelling of soil organic carbon redistribution on landscape scale

    Science.gov (United States)

    Schindewolf, Marcus; Seher, Wiebke; Amorim, Amorim S. S.; Maeso, Daniel L.; Jürgen, Schmidt

    2014-05-01

    Recent studies have pointed out the great importance of erosion processes in global carbon cycling. Continuous erosion leads to a massive loss of top soils including the loss of organic carbon accumulated over long time in the soil humus fraction. Lal (2003) estimates that 20% of the organic carbon eroded with top soils is emitted into atmosphere, due to aggregate breakdown and carbon mineralization during transport by surface runoff. Furthermore soil erosion causes a progressive decrease of natural soil fertility, since cation exchange capacity is associated with organic colloids. As a consequence the ability of soils to accumulate organic carbon is reduced proportionately to the drop in soil productivity. The colluvial organic carbon might be protected from further degradation depending on the depth of the colluvial cover and local decomposing conditions. Some colluvial sites can act as long-term sinks for organic carbon. The erosional transport of organic carbon may have an effect on the global carbon budget, however, it is uncertain, whether erosion is a sink or a source for carbon in the atmosphere. Another part of eroded soils and organic carbon will enter surface water bodies and might be transported over long distances. These sediments might be deposited in the riparian zones of river networks. Erosional losses of organic carbon will not pass over into atmosphere for the most part. But soil erosion limits substantially the potential of soils to sequester atmospheric CO2 by generating humus. The present study refers to lateral carbon flux modelling on landscape scale using the process based EROSION 3D soil loss simulation model, using existing parameter values. The selective nature of soil erosion results in a preferentially transport of fine particles while less carbonic larger particles remain on site. Consequently organic carbon is enriched in the eroded sediment compared to the origin soil. For this reason it is essential that EROSION 3D provides the

  8. Physico-Chemical Properties of Kaolin-Organic Acid

    Directory of Open Access Journals (Sweden)

    Yeo S.W.

    2017-01-01

    Full Text Available Soil with more than 20% of organic content is classified as organic soil in Malaysia. Contents of organic soil consist of different types of organic and inorganic matter. Each type of organic matter has its own characteristic and its effect on the properties of the soil is different. Hence, a good understanding on the effect of specific organic and inorganic matter on the physico-chemical characteristic of organic soils can serve as a guide for predicting the properties of organic soils. The main objective is to unveil the effect of organic acid on the physico-chemical properties of soil. Artificial organic soil (kaolin mixed with organic acid was utilized in order to minimize the geochemical variability of studied soil. The organic acid which consists of humic acid and fulvic acid was extracted from highly humificated plant–based compost. The effect of organic acid on the physico-chemical properties of soil was determined by varying the concentration of organic acid. The specific gravity, Atterberg limits, pH, bulk chemical composition and the functional group of kaolin-organic acid were determined. It was found that the plasticity index, specific gravity and pH value were decreased with lowered concentration of organic acid. However, the liquid limits and plastic limits were found to be increased with the concentration decrement of organic acid. The analysis of XRF on the bulk chemical composition and analysis of FTIR spectra on the functional group of artificial organic soils with different concentration have confirmed little geochemical variability between samples.

  9. Changes in diversity, biomass and abundance of soil macrofauna, Parrotio-Carpinetum forest at organic and semi-organic horizons

    Directory of Open Access Journals (Sweden)

    Masomeh Izadi

    2016-07-01

    Full Text Available Present study evaluates diversity, abundance and biomass of soil macrofauna in organic and semi-organic horizons in Parrotia persica-Carpinus betulus forest in Shast kola area. Totally 70 sample points were randomly selected from organic and semi-organic horizons then sampling was done by a rectangle 100 cm2 area. Soil macrofauna were separated from soil samples by hand sorting and using Berlese funnel then dried at 60°C for 72h and weighted in 0.001 gr. With using taxonomic classification key, thirteen macrofauna orders were identified. Most of abundance of soil macrofauna in both soil horizons were allocated to Millipedes order. Changes in diversity, abundance and biomass of macrofauna in both soil horizons were calculated. The results showed Shannon diversity index, Simpson evenness and Margalef richness indices in semi-organic horizon were more than organic horizon. Abundance and biomass of macrofauna in semi-organic horizon were more than organic horizon.

  10. Repeated soil application of organic waste amendments reduces draught force and fuel consumption for soil tillage

    DEFF Research Database (Denmark)

    Peltrea, Clément; Nyord, Tavs; Bruun, Sander

    2015-01-01

    Abstract Soil application of organic waste products (OWP) can maintain or increase soil organic carbon (SOC) content, which in turn could lead to increased porosity and potentially to reduced energy use for soil tillage. Only a few studies have addressed the effect of SOC content on draught force...... for soil tillage, and this still needs to be addressed for fields that receive diverse types of organic waste of urban, agricultural and agro-industrial origin. The objective of this study was to determine the effect of changes in SOC induced by repeated soil application of OWP on draught force for soil...... tillage and tractor fuel consumption. Draught force was measured for tillage with conventional spring tillage tines, as well as bulk density, soil texture and SOC content in the CRUCIAL field experiment, Denmark in which diverse types of OWP had been applied annually for 11 years. The OWP included...

  11. High plant uptake of radiocesium from organic soils due to Cs mobility and low soil K content

    International Nuclear Information System (INIS)

    Sanchez, A.L.; Wright, S.M.; Naylor, C.; Kennedy, V.H.; Dodd, B.A.; Singleton, D.L.; Barnett, C.L.; Stevens, P.A.

    1999-01-01

    Post-Chernobyl experience has demonstrated that persistently high plant transfer of 137 Cs occurs from organic soils in upland and seminatural ecosystems. The soil properties influencing this transfer have been known for some time but have not been quantified. A pot experiment was conducted using 23 soils collected from selected areas of Great Britain, which were spiked with 134 Cs, and Agrostis capillaris grown for 19--45 days. The plant-to-soil 134 Cs concentration ratio (CR) varied from 0.06 to 44; log CR positively correlated to soil organic matter content (R 2 = 0.84), and CR values were highest for soils with low distribution coefficients (K d ) of 134 Cs. Soils with high organic matter contents and high concentrations of NH 4 + in solution showed high 134 Cs mobility (low K d ). The plant-to-soil solution 134 Cs ratio decreased sharply with increasing soil solution K + . A two parameter linear model, used to predict log CR from soil solution K + and K d , explained 94% of the variability in CR values. In conclusion, the high transfer of 134 Cs in organic soils is related to both the high 134 Cs mobility (low clay content and high NH 4 + concentrations) and low K availability

  12. Compositions and methods of making and using metal-organic framework compositions

    KAUST Repository

    Mohideen, Mohamed Infas Haja; Adil, Karim; Belmabkhout, Youssef; Eddaoudi, Mohamed; Bhatt, Prashant M.

    2017-01-01

    Embodiments of the present disclosure include a metal-organic framework (MOF) composition comprising one or more metal ions, a plurality of organic ligands, and a solvent, wherein the one or more metal ions associate with the plurality of organic ligands sufficient to form a MOF with kag topology. Embodiments of the present disclosure further include a method of making a MOF composition comprising contacting one or more metal ions with a plurality of organic ligands in the presence of a solvent, sufficient to form a MOF with kag topology, wherein the solvent comprises water only. Embodiments of the present disclosure also describe a method of capturing chemical species from a fluid composition comprising contacting a MOF composition with kag topology and pore size of about 3.4Å to 4.8Å with a fluid composition comprising two or more chemical species and capturing one or more captured chemical species from the fluid composition.

  13. Compositions and methods of making and using metal-organic framework compositions

    KAUST Repository

    Mohideen, Mohamed Infas Haja

    2017-05-04

    Embodiments of the present disclosure include a metal-organic framework (MOF) composition comprising one or more metal ions, a plurality of organic ligands, and a solvent, wherein the one or more metal ions associate with the plurality of organic ligands sufficient to form a MOF with kag topology. Embodiments of the present disclosure further include a method of making a MOF composition comprising contacting one or more metal ions with a plurality of organic ligands in the presence of a solvent, sufficient to form a MOF with kag topology, wherein the solvent comprises water only. Embodiments of the present disclosure also describe a method of capturing chemical species from a fluid composition comprising contacting a MOF composition with kag topology and pore size of about 3.4Å to 4.8Å with a fluid composition comprising two or more chemical species and capturing one or more captured chemical species from the fluid composition.

  14. Sorption of perfluoroalkyl substances (PFASs) to an organic soil horizon - Effect of cation composition and pH.

    Science.gov (United States)

    Campos Pereira, Hugo; Ullberg, Malin; Kleja, Dan Berggren; Gustafsson, Jon Petter; Ahrens, Lutz

    2018-09-01

    Accurate prediction of the sorption of perfluoroalkyl substances (PFASs) in soils is essential for environmental risk assessment. We investigated the effect of solution pH and calculated soil organic matter (SOM) net charge on the sorption of 14 PFASs onto an organic soil as a function of pH and added concentrations of Al 3+ , Ca 2+ and Na + . Often, the organic C-normalized partitioning coefficients (K OC ) showed a negative relationship to both pH (Δlog K OC /ΔpH = -0.32 ± 0.11 log units) and the SOM bulk net negative charge (Δlog K OC  = -1.41 ± 0.40 per log unit mol c g -1 ). Moreover, perfluorosulfonic acids (PFSAs) sorbed more strongly than perfluorocarboxylic acids (PFCAs) and the PFAS sorption increased with increasing perfluorocarbon chain length with 0.60 and 0.83 log K OC units per CF 2 moiety for C 3 -C 10 PFCAs and C 4 , C 6 , and C 8 PFSAs, respectively. The effects of cation treatment and SOM bulk net charge were evident for many PFASs with low to moderate sorption (C 5 -C 8 PFCAs and C 6 PFSA). However for the most strongly sorbing and most long-chained PFASs (C 9 -C 11 and C 13 PFCAs, C 8 PFSA and perfluorooctane sulfonamide (FOSA)), smaller effects of cations were seen, and instead sorption was more strongly related to the pH value. This suggests that the most long-chained PFASs, similar to other hydrophobic organic compounds, are preferentially sorbed to the highly condensed domains of the humin fraction, while shorter-chained PFASs are bound to a larger extent to humic and fulvic acid, where cation effects are significant. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Stability of Soil Organic Matter in Alpine Ecosystems: No Relationship with Vegetation

    Science.gov (United States)

    Matteodo, M.; Sebag, D.; Vittoz, P.; Verrecchia, E. P.

    2016-12-01

    There is an emerging understanding of mechanisms governing soil organic matter (SOM) stability, which is challenging the historical view of carbon persistence1. According to this alternative vision, SOM stability is not directly regulated by the molecular structure of plant inputs (i.e. the historical view), but the biotic and abiotic conditions of the surrounding environment which play a major role and mediate the influence of compound chemistry. The persistence of SOM is thus influenced by ecological conditions, controlling the access and activity of decomposers' enzymes and being ecosystem-dependent. In this study, we investigated differences of (1) carbon content, and (2) stability of organic matter in litter and organomineral layers from the most widespread plant communities at the subalpine-alpine level of the Swiss Alps. For this purpose, 230 samples from 47 soil profiles have been analysed across seven plant communities, along a subalpine-alpine elevation gradient. Both calcareous and siliceous grasslands were studied, as well as snowbed and ridge communities. Aboveground litter and A horizons were sampled and analysed using Rock-Eval Pyrolysis, a proxy-technique commonly used for the investigation of organic matter composition and stability2,3. Results show that the litter layers of the seven plant communities are significantly different in terms of total organic carbon (TOC) content, but slightly variable in terms of stability. The situation is radically different in the organomineral horizons where the amount of organic carbon is interestingly homogeneous, as well as the SOM stability. In mineral horizons, the amount and stability of SOM are mainly driven by the geological settings, and therefore vary in the different plant communities. These results show a clear disconnection between organic, organomineral, and mineral horizons in terms of factors governing soil organic matter stability. Consistent with the recent view of the carbon balance, plant input

  16. Steel-soil composite bridge

    DEFF Research Database (Denmark)

    Du, Guangli; Pettersson, Lars; Karoumi, Raid

    2017-01-01

    viability, while their environmental performance is overlooked. Today’s designers are urged to seek new design options to reduce the environmental burdens. Sweden owns more than 24574 bridges and most of them are short spans. Among them, the slab frame bridge (CFB) is a common solution. Soil steel composite...... bridge (SSCB), alternatively, is a functionally equivalent solution to CFB and shows advantages in low cost and easy construction. This paper compares the environmental performance between these two bridge types based on life cycle assessment (LCA). The analysis and result shows that, the SSCB...

  17. Can Biochar Protect Labile Organic Matter Against Mineralization in Soil?

    Institute of Scientific and Technical Information of China (English)

    Giovanna B.MELAS; Oriol ORTIZ; Josep M.ALACA(N)IZ

    2017-01-01

    Biochar could help to stabilize soil organic (SOM) matter,thus sequestering carbon (C) into the soil.The aim of this work was to determine an easy method i) to estimate the effects of the addition of biochar and nutrients on the organic matter (SOM)mineralization in an artificial soil,proposed by the Organization for Economic Co-operation and Development (OECD),amended with glucose and ii) to measure the amount of labile organic matter (glucose) that can be sorbed and thus be partially protected in the same soil,amended or not amended with biochar.A factorial experiment was designed to check the effects of three single factors (biochar,nutrients,and glucose) and their interactions on whole SOM mineralization.Soil samples were inoculated with a microbial inoculum and preincubated to ensure that their biological activities were not limited by a small amount of microbial biomass,and then they were incubated in the dark at 21 ℃ for 619 d.Periodical measurements of C mineralized to carbon dioxide (CO2) were carried out throughout the 619-d incubation to allow the mineralization of both active and slow organic matter pools.The amount of sorbed glucose was calculated as the difference between the total and remaining amounts of glucose added in a soil extract.Two different models,the Freundlich and Langmuir models,were selected to assess the equilibrium isotherms of glucose sorption.The CO2-C release strongly depended on the presence of nutrients only when no biochar was added to the soil.The mineralization of organic matter in the soil amended with both biochar and glucose was equal to the sum of the mineralization of the two C sources separately.Furthermore,a significant amount of glucose can be sorbed on the biochar-amended soil,suggesting the involvement of physico-chemical mechanisms in labile organic matter protection.

  18. Organic fertilization alters the community composition of root associated fungi in Pisum sativum

    DEFF Research Database (Denmark)

    Yu, L.; Nicolaisen, M.; Ravnskov, S.

    2013-01-01

    Organic fertilization is well known to affect individual functional groups of root associated fungi such as arbuscular mycorrhizal (AM) fungi and root pathogens, but limited information is available on the effect of organic fertilization at the fungal community composition level. The main objective...... of the present study was to examine the response of communities of root associated fungi in Pisum sativum to Protamylasse, an organic fertilizer used in pea production. Plants were grown in pots with field soil amended with four different levels of Protamylasse. 454 pyrosequencing was employed to examine......, the organic fertilizer Protamylasse clearly affects communities of root associated fungi, which seems to be linked to the life strategy of the different functional groups of root associated fungi. --------------------------------------------------------------------------------...

  19. Soils, time, and primate paleoenvironments

    Science.gov (United States)

    Bown, T.M.; Kraus, M.J.

    1993-01-01

    Soils are the skin of the earth. From both poles to the equator, wherever rocks or sediment are exposed at the surface, soils are forming through the physical and chemical action of climate and living organisms. The physical attributes (color, texture, thickness) and chemical makeup of soils vary considerably, depending on the composition of the parent material and other variables: temperature, rainfall and soil moisture, vegetation, soil fauna, and the length of time that soil-forming processes have been at work. United States soil scientists1 have classified modern soils into ten major groups and numerous subgroups, each reflecting the composition and architecture of the soils and, to some extent, the processes that led to their formation. The physical and chemical processes of soil formation have been active throughout geologic time; the organic processes have been active at least since the Ordovician.2 Consequently, nearly all sedimentary rocks that were deposited in nonmarine settings and exposed to the elements contain a record of ancient, buried soils or paleosols. A sequence of these rocks, such as most ancient fluvial (stream) deposits, provides a record of soil paleoenvironments through time. Paleosols are also repositories of the fossils of organisms (body fossils) and the traces of those organisms burrowing, food-seeking, and dwelling activities (ichnofossils). Indeed, most fossil primates are found in paleosols. Careful study of ancient soils gives new, valuable insights into the correct temporal reconstruction of the primate fossil record and the nature of primate paleoenvironments. ?? 1993 Wiley-Liss, Inc.

  20. Organic Acids Regulation of Chemical-Microbial Phosphorus Transformations in Soils.

    Science.gov (United States)

    Menezes-Blackburn, Daniel; Paredes, Cecilia; Zhang, Hao; Giles, Courtney D; Darch, Tegan; Stutter, Marc; George, Timothy S; Shand, Charles; Lumsdon, David; Cooper, Patricia; Wendler, Renate; Brown, Lawrie; Blackwell, Martin; Wearing, Catherine; Haygarth, Philip M

    2016-11-01

    We have used an integrated approach to study the mobility of inorganic phosphorus (P) from soil solid phase as well as the microbial biomass P and respiration at increasing doses of citric and oxalic acid in two different soils with contrasting agronomic P status. Citric or oxalic acids significantly increased soil solution P concentrations for doses over 2 mmol kg -1 . However, low organic acid doses (<2 mmol kg -1 ) were associated with a steep increase in microbial biomass P, which was not seen for higher doses. In both soils, treatment with the tribasic citric acid led to a greater increase in soil solution P than the dibasic oxalic acid, likely due to the rapid degrading of oxalic acids in soils. After equilibration of soils with citric or oxalic acids, the adsorbed-to-solution distribution coefficient (K d ) and desorption rate constants (k -1 ) decreased whereas an increase in the response time of solution P equilibration (T c ) was observed. The extent of this effect was shown to be both soil and organic acid specific. Our results illustrate the critical thresholds of organic acid concentration necessary to mobilize sorbed and precipitated P, bringing new insight on how the exudation of organic acids regulate chemical-microbial soil phosphorus transformations.

  1. Urban tree effects on soil organic carbon.

    Directory of Open Access Journals (Sweden)

    Jill L Edmondson

    Full Text Available Urban trees sequester carbon into biomass and provide many ecosystem service benefits aboveground leading to worldwide tree planting schemes. Since soils hold ∼75% of ecosystem organic carbon, understanding the effect of urban trees on soil organic carbon (SOC and soil properties that underpin belowground ecosystem services is vital. We use an observational study to investigate effects of three important tree genera and mixed-species woodlands on soil properties (to 1 m depth compared to adjacent urban grasslands. Aboveground biomass and belowground ecosystem service provision by urban trees are found not to be directly coupled. Indeed, SOC enhancement relative to urban grasslands is genus-specific being highest under Fraxinus excelsior and Acer spp., but similar to grasslands under Quercus robur and mixed woodland. Tree cover type does not influence soil bulk density or C∶N ratio, properties which indicate the ability of soils to provide regulating ecosystem services such as nutrient cycling and flood mitigation. The trends observed in this study suggest that genus selection is important to maximise long-term SOC storage under urban trees, but emerging threats from genus-specific pathogens must also be considered.

  2. Soil mixing design methods and construction techniques for use in high organic soils : [summary].

    Science.gov (United States)

    2015-10-01

    The soils which serve as foundations for construction projects may be roughly classified as : inorganic or organic. Inorganic soils vary in firmness and suitability for construction. Soft : or loose inorganic soils may be stabilized using cement or s...

  3. Temporal dynamics of the compositions and activities of soil microbial communities post-application of the insecticide chlorantraniliprole in paddy soils.

    Science.gov (United States)

    Wu, Meng; Liu, Jia; Li, Weitao; Liu, Ming; Jiang, Chunyu; Li, Zhongpei

    2017-10-01

    Chlorantraniliprole (CAP) is a newly developed insecticide widely used in rice fields in China. There has been few studies evaluating the toxicological effects of CAP on soil-associated microbes. An 85-day microcosm experiment was performed to reveal the dissipation dynamics of CAP in three types of paddy soils in subtropical China. The effects of CAP on microbial activities (microbial biomass carbon-MBC, basal soil respiration-BSR, microbial metabolic quotient-qCO 2 , acid phosphatase and sucrose invertase activities) in the soils were periodically evaluated. Microbial phospholipid fatty acid (PLFA) analysis was used to evaluate the change of soil microbial community composition on day 14 and 50 of the experiment. CAP residues were extracted using the quick, easy, cheap, effective, rugged, and safe (QuChERS) method and quantification was measured by high performance liquid chromatography (HPLC). The half-lives (DT 50 ) of CAP were in the range of 41.0-53.0 days in the three soils. The results showed that CAP did not impart negative effects on MBC during the incubation. CAP inhibited BSR, qCO 2 , acid phosphatase and sucrose invertase activities in the first 14 days of incubation in all the soils. After day 14, the soil microbial parameters of CAP-treated soils became statistically at par with their controls. Principal component analysis (PCA) determining abundance of biomarker PLFAs indicated that the application of CAP significantly changed the compositions of microbial communities in all three paddy soils on day 14 but the compositions of soil microbial communities recovered by day 50. This study indicates that CAP does not ultimately impair microbial activities and microbial compositions of these three paddy soil types. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Elemental, stable isotopic and biochemical characterization of soil organic matter alteration across a natural peatland gradient

    Science.gov (United States)

    Cowie, G.; Mowbray, S.; Belyea, L.; Laing, C.; Allton, K.; Abbott, G.; Muhammad, A.

    2010-12-01

    Northern peatlands store around one third of global soil C and thus represent a key reservoir. To elucidate how these systems might respond to climate change, field- and laboratory-based experimental incubation studies are being conducted at sites across a natural peatland gradient in the boreonemoral zone of central Sweden (Ryggmossen). The site comprises four successional stages, from edge to centre; Swamp Forest (SF), Lagg Fen (LF), Bog Margin (BM) and Bog Plateau (BP). The well-preserved succession shows strong decreases in mineral cations and pH, and distinct changes in vegetation and water-table depth. As an underpinning to these experiments, comprehensive characterization of natural soil organic matter (SOM) alteration has been carried out through detailed analyses of vegetation and downcore profiles at contrasting topographic sites (hummock vs hollow) in each of the four locations. As illustrated in Figure 1, while some similarities occur in downcore trends, contrasts are observed in C and N elemental and stable isotopic compositions, between stages and, in some cases, between microtopographic settings. Downcore trends and intersite differences are also observed in biochemical yields and molecular composition (carbohydrates, amino acids, phenols, lipids and D/L amino acid ratios). These reflect SOM decay and alteration combined with the effects of contrasting hydrologic, redox and nutrient regimes and differing vegetation and microbial inputs at each of the study sites. Multivariate analysis is used to to elucidate compositional patterns that characterize and delineate progressive SOM decay, specific vegetation types, and the effects of contrasting environmental conditions at the different sites. Figure 1. A. Organic carbon content (wt %), B. Atomic ratio of organic C to total N, C. Stable C isotopic composition of organic C (d13Corg), and D. Stable N isotopic composition of total nitrogen (d15N), all for core profiles from contrasting settings (hummock and

  5. Wettability, soil organic matter and structure-properties of typical chernozems under the forest and under the arable land

    Science.gov (United States)

    Bykova, Galina; Umarova, Aminat; Tyugai, Zemfira; Milanovskiy, Evgeny; Shein, Evgeny

    2017-04-01

    Intensive tillage affects the properties of soil: decrease in content of soil organic matter and in hydrophobicity of the soil's solid phase, the reduction of amount of water stable aggregates - all this leads to deterioration of the structure of the soil and affects the process of movement of moisture in the soil profile. One of the hypotheses of soil's structure formation ascribes the formation of water stable aggregates with the presence of hydrophobic organic substances on the surface of the soil's solid phase. The aim of this work is to study the effect of tillage on properties of typical chernozems (pachic Voronic Chernozems, Haplic Chernozems) (Russia, Kursk region), located under the forest and under the arable land. The determination of soil-water contact angle was performed by a Drop Shape Analyzer DSA100 (Krüss GmbH, Germany) by the static sessile drop method. For all samples the content of total and organic carbon by dry combustion in oxygen flow and the particle size distribution by the laser diffraction method on the device Analysette 22 comfort, FRITCH, Germany were determined. The estimation of aggregate composition was performed by dry sieving (AS 200, Retsch, Germany), the content of water stable aggregates was estimated by the Savvinov method. There was a positive correlation between the content of organic matter and soil's wettability in studied soils, a growth of contact angle with the increasing the content of organic matter. Under the forest the content of soil organic matter was changed from 6,41% on the surface up to 1,9% at the depth of 100 cm. In the Chernozem under the arable land the organic carbon content in arable horizon is almost two times less. The maximum of hydrophobicity (78.1o) was observed at the depth of 5 cm under the forest. In the profile under the arable land the contact angle value at the same depth was 50o. The results of the structure analysis has shown a decrease in the content of agronomically valuable and water

  6. Visualization of soil particulate organic matter by means of X-ray CT?

    Science.gov (United States)

    Sleutel, Steven; Van Loo, Denis; Maenhout, Peter; Van Hoorebeke, Luc; Cnudde, Veerle; De Neve, Stefaan

    2014-05-01

    composition of the soil mineral matrix. Furthermore, techniques such as multiple-energy scanning and K-edge imaging, even in the future perhaps in combination with spectral resolving detectors or spectroscopic techniques can could further enhance the potential benefit from this study of X-ray CT staining agents. The high Z elements of the staining agents have unique and characteristic traits that can be detected or quantified with the abovementioned techniques and methods. We conclude that, given resolution limits and inherent presence of partial volume effects staining, X-ray CT-based localization of discrete SOM particles will be limited to a lower limit of 20-50 µm. Still, the improved 3D visualization of OM and soil pore space opens up possibilities for tailored lab experiments with measures of microbial activity, which could generate new insights in carbon cycling at small scales. In addition, we report on a lab incubation experiment in which CO2 respiration from soil cores was monitored (headspace GC analysis) and an X-ray CT approach yielded soil pore size distributions. We incubated a sandy loam soil (with application of ground grass or sawdust) in 18 small aluminium rings (Ø 1 cm, h 1 cm). Bulk density was adjusted to 1.1 or 1.3 Mg m-3 (compaction) and 6 rings were filled at a coarser Coarse Sand:Fine Sand:Silt+Clay ratio. While compaction induced a strong reduction in the cumulative C mineralization for both grass and sawdust substrates, artificial change to a coarser soil texture only reduced net C mineralization from the added sawdust. There thus appears to be a strong interaction effect between soil pore structure and substrate type on substrate decomposition. Correlation coefficients between the C mineralization rates and volumes of 7 pore size classes (from the X-ray CT data) also showed an increasing positive correlation with increasing pore size. Since any particulate organic matter initially present in the soil was removed prior to the experiment (sieving

  7. Chemical Compositions of Soils in Parts of Edo State, Southwest ...

    African Journals Online (AJOL)

    MICHAEL HORSFALL

    www.bioline.org.br/ja. Chemical Compositions of Soils in Parts of Edo State, Southwest Nigeria and their ... the soil in agriculture and engineering (Imasuen et al. 1989b). Clay mineral ..... Unpublished Ph.D. Thesis, The. University of Western ...

  8. Aliphatic, cyclic, and aromatic organic acids, vitamins, and carbohydrates in soil: a review.

    Science.gov (United States)

    Vranova, Valerie; Rejsek, Klement; Formanek, Pavel

    2013-11-10

    Organic acids, vitamins, and carbohydrates represent important organic compounds in soil. Aliphatic, cyclic, and aromatic organic acids play important roles in rhizosphere ecology, pedogenesis, food-web interactions, and decontamination of sites polluted by heavy metals and organic pollutants. Carbohydrates in soils can be used to estimate changes of soil organic matter due to management practices, whereas vitamins may play an important role in soil biological and biochemical processes. The aim of this work is to review current knowledge on aliphatic, cyclic, and aromatic organic acids, vitamins, and carbohydrates in soil and to identify directions for future research. Assessments of organic acids (aliphatic, cyclic, and aromatic) and carbohydrates, including their behaviour, have been reported in many works. However, knowledge on the occurrence and behaviour of D-enantiomers of organic acids, which may be abundant in soil, is currently lacking. Also, identification of the impact and mechanisms of environmental factors, such as soil water content, on carbohydrate status within soil organic matter remains to be determined. Finally, the occurrence of vitamins in soil and their role in biological and biochemical soil processes represent an important direction for future research.

  9. Aliphatic, Cyclic, and Aromatic Organic Acids, Vitamins, and Carbohydrates in Soil: A Review

    Directory of Open Access Journals (Sweden)

    Valerie Vranova

    2013-01-01

    Full Text Available Organic acids, vitamins, and carbohydrates represent important organic compounds in soil. Aliphatic, cyclic, and aromatic organic acids play important roles in rhizosphere ecology, pedogenesis, food-web interactions, and decontamination of sites polluted by heavy metals and organic pollutants. Carbohydrates in soils can be used to estimate changes of soil organic matter due to management practices, whereas vitamins may play an important role in soil biological and biochemical processes. The aim of this work is to review current knowledge on aliphatic, cyclic, and aromatic organic acids, vitamins, and carbohydrates in soil and to identify directions for future research. Assessments of organic acids (aliphatic, cyclic, and aromatic and carbohydrates, including their behaviour, have been reported in many works. However, knowledge on the occurrence and behaviour of D-enantiomers of organic acids, which may be abundant in soil, is currently lacking. Also, identification of the impact and mechanisms of environmental factors, such as soil water content, on carbohydrate status within soil organic matter remains to be determined. Finally, the occurrence of vitamins in soil and their role in biological and biochemical soil processes represent an important direction for future research.

  10. Aliphatic, Cyclic, and Aromatic Organic Acids, Vitamins, and Carbohydrates in Soil: A Review

    Science.gov (United States)

    Vranova, Valerie; Rejsek, Klement; Formanek, Pavel

    2013-01-01

    Organic acids, vitamins, and carbohydrates represent important organic compounds in soil. Aliphatic, cyclic, and aromatic organic acids play important roles in rhizosphere ecology, pedogenesis, food-web interactions, and decontamination of sites polluted by heavy metals and organic pollutants. Carbohydrates in soils can be used to estimate changes of soil organic matter due to management practices, whereas vitamins may play an important role in soil biological and biochemical processes. The aim of this work is to review current knowledge on aliphatic, cyclic, and aromatic organic acids, vitamins, and carbohydrates in soil and to identify directions for future research. Assessments of organic acids (aliphatic, cyclic, and aromatic) and carbohydrates, including their behaviour, have been reported in many works. However, knowledge on the occurrence and behaviour of D-enantiomers of organic acids, which may be abundant in soil, is currently lacking. Also, identification of the impact and mechanisms of environmental factors, such as soil water content, on carbohydrate status within soil organic matter remains to be determined. Finally, the occurrence of vitamins in soil and their role in biological and biochemical soil processes represent an important direction for future research. PMID:24319374

  11. USE OF ORGANIC RESIDUES FOR THE RECOVERY OF SOIL AND ENVIRONMENTAL SUSTAINABILITY

    Directory of Open Access Journals (Sweden)

    Antonia Galvez

    2011-12-01

    Full Text Available The aim of this work was to investigate the effects of different organic residues on soil fertility and climate change, through the evaluation of soil organic matter mineralisation, greenhouse gas emission, nutrient availability and soil microbial biomass content and activity. A degraded agricultural soil was amended with three different organic residues (pig slurry digestate, rapeseed meal, and compost at three different doses (0.1, 0.25 and 0.5% w/w and incubated for 30 days at 20 ºC. During incubation, soil CO2 and N2O emissions, K2SO4 extractable organic C, N, NH4+, NO3- and P, soil microbial biomass and some enzymatic activities were determined. Results obtained showed that rapeseed meal and pig slurry are best suited to improve soil chemical and biological fertility, while compost is more appropriate for the enhancement of soil organic matter content and to promote soil C sequestration.

  12. Organic and inorganic amendment application on mercury-polluted soils: effects on soil chemical and biochemical properties.

    Science.gov (United States)

    García-Sánchez, Mercedes; Klouza, Martin; Holečková, Zlata; Tlustoš, Pavel; Száková, Jiřina

    2016-07-01

    On the basis of a previous study performed in our laboratory, the use of organic and inorganic amendments can significantly modify the Hg mobility in soil. We have compared the effectiveness of organic and inorganic amendments such as digestate and fly ash, respectively, reducing the Hg mobility in Chernozem and Luvisol soils differing in their physicochemical properties. Hence, the aim of this work was to compare the impact of digestate and fly ash application on the chemical and biochemical parameters in these two mercury-contaminated soils in a model batch experiment. Chernozem and Luvisol soils were artificially contaminated with Hg and then incubated under controlled conditions for 21 days. Digestate and fly ash were applied to both soils in a dose of 10 and 1.5 %, respectively, and soil samples were collected after 1, 7, 14, and 21 days of incubation. The presence of Hg in both soils negatively affected to processes such as nitrification, provoked a decline in the soil microbial biomass C (soil microbial biomass C (MBC)), and the microbial activities (arylsulfatase, and β-glucosaminidase) in both soils. Meanwhile, the digestate addition to Chernozem and Luvisol soils contaminated with Hg improved the soil chemical properties (pH, dissolved organic carbon (DOC), N (Ntot), inorganic-N forms (N-NH4 (+) and N-NO3 (-))), as consequence of high content in C and N contained in digestate. Likewise, the soil MBC and soil microbial activities (dehydrogenase, arylsulfatase, and β-glucosaminidase) were greatly enhanced by the digestate application in both soils. In contrast, fly ash application did not have a remarkable positive effect when compared to digestate in Chernozem and Luvisol soil contaminated with mercury. These results may indicate that the use of organic amendments such as digestate considerably improved the soil health in Chernozem and Luvisol compared with fly ash, alleviating the detrimental impact of Hg. Probably, the chemical properties present in

  13. Soil Fertility Status on Organic Paddy Experiment

    Directory of Open Access Journals (Sweden)

    Mujiyo

    2015-07-01

    Full Text Available The study aims to determine fertility status of the soil after organic paddy experiments using kinds and doses of organic fertilizers. Experiment was conducted at greenhouse laboratory in Faculty of Agriculture Sebelas Maret University Surakarta. Experimental design used completely randomized design with 9 kinds of treatment was replicated 3 times. Experiments were the use of cow manure, Azolla fertilizer, Azolla inoculum and its combinations that are based on fulfilling nutrient requirements of 120 kg N ha-1. Result shows that the use of cow manure, Azolla fertilizers and Azolla inoculum had no effect on changes of soil fertility status. Soil fertility status was not significantly correlated with cow manure (0,16ns, Azolla fertilizer (0,26ns and Azolla inoculum (0,16ns. Average of final soil fertility status included fertile category, which was similar as the initial soil fertility status. Average of final soil properties of treatment but nevertheless was relatively higher than in no treatment, indicating the use of cow manure, Azolla fertilizer, Azolla inoculum and its combinations had greater impact to soil properties. Cow manure despite increased available K2O and dry grain, but it did not significantly increase the soil fertility status from fertile to very fertile. This was presumably due to the relatively short experiment period, only one planting season had not given significant effect to soil properties. Implication of this study is the use of cow manure, Azolla fertilizer, Azolla inoculum and its combinations although did not increase the soil fertility status but could maintain soil fertility status as the initial conditions before planting.

  14. Behavior of oxyfluorfen in soils amended with different sources of organic matter. Effects on soil biology.

    Science.gov (United States)

    Gómez, Isidoro; Rodríguez-Morgado, Bruno; Parrado, Juan; García, Carlos; Hernández, Teresa; Tejada, Manuel

    2014-05-30

    We performed a laboratory study on the effect of oxyfluorfen at a rate of 4lha(-1) on biological properties of a soil amended with four organic wastes (two biostimulants/biofertilizers, obtained from rice bran, RB1 and RB2; municipal solid waste, MSW; and sheep manure, SM). Soil was mixed with SM at a rate of 1%, MSW at a rate of 0.52%, RB1 at a rate of 0.39% and RB2 at a rate of 0.30%, in order to apply the same amount of organic matter to the soil. The enzymatic activities and microbial community in the soil were determined during the incubation times. The application of RB1 and RB2 to soil without oxyfluorfen increased the enzymatic activities and biodiversity, peaking at day 10 of the incubation period. This stimulation was higher in the soil amended with RB2 than in that amended with RB1. In SM and CF-amended soils, the stimulation of enzymatic activities and soil biodiversity increased during the experiment. The application of herbicide in organic-amended soils decreased the inhibition of soil enzymatic activities and soil biodiversity. Possibly the low molecular weight protein content easily assimilated by soil microorganisms and the higher fat content in the biostimulants/biofertilizers are responsible for the lower inhibition of these soil biological properties. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Seasonal changes in the chemical quality and biodegradability of dissolved organic matter exported from soils to streams in coastal temperate rainforest watersheds

    Science.gov (United States)

    Jason B. Fellman; Eran Hood; David V. D' Amore; Richard T. Edwards; Dan White

    2009-01-01

    The composition and biodegradability of streamwater dissolved organic matter (DOM) varies with source material and degree of transformation. We combined PARAFAC modeling of fluorescence excitation-emission spectroscopy and biodegradable dissolved organic carbon (BDOC) incubations to investigate seasonal changes in the lability of DOM along a soil-stream continuum in...

  16. Biological oxygen demand in soils and hydrogel compositions for plant protection of the rhizosphere

    Science.gov (United States)

    Valentinovich Smagin, Andrey

    2018-02-01

    Potential biological activity of mineral and organogenic samples from light-textured sod-podzolic soils as well as of hydrogel compositions for protecting the root layer from pathogenic microflora and unfavorable edaphic factors were studied in laboratory conditions by oxygen consumption under the optimal hydrothermic conditions with portable gas analyzers. We have conducted ecological standardization of biological activity and organic matter destruction estimated by biological oxygen demand (BOD) in the widespread sandy soils. The primary outcome was the scale of gradations of biological oxygen uptake in soils with a range of quantities of potential biological activity from “very low” (140 g·m-3·hour-1), obtained on the basis of statistical processing of data array 1308 measurements. Acrylic polymer hydrogels had BOD = 0.2-2 g·m-3·hour-1, which corresponded to the periods of their half-lives from 0.2±0.1 to 6.8± 4.5 years, or relatively low resistance to biodestruction. In contrast to the pure gels, hydrogel compositions for rhizosphere based on ionic and colloidal silver showed low biological activity (BOD=0.01-0.2 g·m-3· hour-1) and, accordingly, significant resistance to biodegradation with half-lives from 5 to 70 years and above.

  17. Assessment of Soil Water Composition in the Northern Taiga Coniferous Forests of Background Territories in the Industrially Developed Region

    Science.gov (United States)

    Lukina, N. V.; Ershov, V. V.; Gorbacheva, T. T.; Orlova, M. A.; Isaeva, L. G.; Teben'kova, D. N.

    2018-03-01

    The composition of soil water under coniferous forests of Murmansk oblast—an industrially developed region of northern Russia—was investigated. The studied objects were dwarf-shrub-green-moss spruce forests and dwarf-shrub-lichen pine forests on Al-Fe-humus podzols ( Albic Rustic Podzols) that are widespread in the boreal zone. The concentrations and removal of organic carbon performing the most important biogeochemical and pedogenic functions were estimated. The results proved significant intra- and inter-biogeocenotic variability in the composition of atmospheric depositions and soil water. Carbon removal with soil water from organic and mineral horizons within elementary biogeoareas (EBGA) under tree crowns was 2-5 and 2-3 times (in some cases, up to 10 times) greater than that in the intercrown areas, respectively. The lowest critical level of mineral nitrogen (0.2 mg/L) was, as a rule, exceeded in tree EBGAs contrary to intercrown areas. Concentrations of sulfates and heavy metals in water of tree EBGA were 3-5 times greater than those in inter-crown areas. Significant inter-biogeocenotic variations related to differences in the height of trees and tree stand density were found. It is argued that adequate characterization of biochemical cycles and assessment of critical levels of components in soil water of forest ecosystems should be performed with due account for the intra- and inter-biogeocenotic variability.

  18. Influence of soil solution cation composition on boron adsorption by soils

    Science.gov (United States)

    Boron (B) adsorption on five arid-zone soil samples from California was investigated as a function of solution pH (4-10) and cation composition (Na, Ca, or Mg). Boron adsorption increased with increasing solution pH, reached an adsorption maximum near pH 9, and decreased with further increases with...

  19. Water repellency of clay, sand and organic soils in Finland

    Directory of Open Access Journals (Sweden)

    K. RASA

    2008-12-01

    Full Text Available Water repellency (WR delays soil wetting process, increases preferential flow and may give rise to surface runoff and consequent erosion. WR is commonly recognized in the soils of warm and temperate climates. To explore the occurrence of WR in soils in Finland, soil R index was studied on 12 sites of different soil types. The effects of soil management practice, vegetation age, soil moisture and drying temperature on WR were studied by a mini-infiltrometer with samples from depths of 0-5 and 5-10 cm. All studied sites exhibited WR (R index >1.95 at the time of sampling. WR increased as follows: sand (R = 1.8-5.0 < clay (R = 2.4-10.3 < organic (R = 7.9-undefined. At clay and sand, WR was generally higher at the soil surface and at the older sites (14 yr., where organic matter is accumulated. Below 41 vol. % water content these mineral soils were water repellent whereas organic soil exhibited WR even at saturation. These results show that soil WR also reduces water infiltration at the prevalent field moisture regime in the soils of boreal climate. The ageing of vegetation increases WR and on the other hand, cultivation reduces or hinders the development of WR.;

  20. Fire Frequency and Vegetation Composition Influence Soil Nitrogen Cycling and Base Cations in an Oak Savanna Ecosystem

    Science.gov (United States)

    McLauchlan, K. K.; Nelson, D. M.; Perakis, S.; Marcotte, A. L.

    2017-12-01

    Fire frequency is crucial for maintaining savannas in the transition between forests and grasslands. In general, increasing fire frequency has two effects: it increases herbaceous plant cover more than woody plant cover, and it lowers soil organic matter stocks. These effects have been demonstrated at a long-term prescribed fire experiment in an oak savanna ecosystem at Cedar Creek Ecosystem Science Reserve, Minnesota, U.S.A. The fire experiment began in 1964 and oak savannas are burned at various frequencies ranging from every year to not at all. This has led to changes in vegetation ranging from almost 100% grassland to 100% oak forest. Additionally, nitrogen stocks almost doubled in the sites that were not burned, as it accumulated in the trees, leaf litter, and soil. We addressed additional soil changes taking place at this experiment by asking the question: How have fire and oak-grass balance affected soil nutrients, specifically nitrogen and base cations? Surface soils were collected from 12 plots on the oak savanna burn experiment. Soils were collected in increments to 100 cm depth, from under grass-dominated vegetation and from under tree-dominated vegetation. We non-destructively estimated soil base cations by measuring elemental concentrations of dried soil subsamples with a handheld x-ray fluorescence analyzer. We also measured carbon and nitrogen concentrations and isotopic composition of the soil samples. Soils in plots with high fire frequency had higher concentrations of calcium than soils in unburned plots (low fire frequency). Similar trends were seen for soil potassium, magnesium, and phosphorus concentrations. In contrast, soils in plots with high fire frequency had dramatically lowered nitrogen cycling rates and stocks across the oak savanna. The contrast between the responses of different nutrients to changing fire frequency has important implications for the consequences of fire and tree-grass composition on nutrient cycling dynamics.

  1. Extractability of water-soluble soil organic matter as monitored by spectroscopic and chromatographic analyses.

    Science.gov (United States)

    Nkhili, Ezzhora; Guyot, Ghislain; Vassal, Nathalie; Richard, Claire

    2012-07-01

    Cold and hot water processes have been intensively used to recover soil organic matter, but the effect of extraction conditions on the composition of the extracts were not well investigated. Our objective was to optimize the extraction conditions (time and temperature) to increase the extracted carbon efficiency while minimizing the possible alteration of water extractable organic matter of soil (WEOM). WEOM were extracted at 20°C, 60°C, or 80°C for 24 h, 10-60 min, and 20 min, respectively. The different processes were compared in terms of pH of suspensions, yield of organic carbon, spectroscopic properties (ultraviolet-visible absorption and fluorescence), and by chromatographic analyses. For extraction at 60°C, the time 30 min was optimal in terms of yield of organic carbon extracted and concentration of absorbing and fluorescent species. The comparison of WEOM 20°C, 24 h; 60°C, 30 min; and 80°C, 20 min highlighted significant differences. The content of total organic carbon, the value of specific ultraviolet absorbance (SUVA(254)), the absorbance ratio at 254 and 365 nm (E (2)/E (3)), and the humification index varied in the order: WEOM (20°C, 24 h) < WEOM (80°C, 20 min) < WEOM (60°C, 30 min). The three WEOM contained common fluorophores associated with simple aromatic structures and/or fulvic-like and common peaks of distinct polarity as detected by ultra performance liquid chromatography. For the soil chosen, extraction at 60°C for 30 min is the best procedure for enrichment in organic chemicals and minimal alteration of the organic matter.

  2. Soil health: a comparison between organically and conventionally managed arable soils in the Netherlands

    NARCIS (Netherlands)

    Diepeningen, van A.D.; Blok, W.J.; Korthals, G.W.; Bruggen, van A.H.C.; Ariena, H.C.

    2005-01-01

    A comparative study of 13 organic and 13 neighboring conventional arable farming systems was conducted in the Netherlands to determine the effect of management practices on chemical and biological soil properties and soil health. Soils were analyzed using a polyphasic approach combining traditional

  3. A simple approach to estimate soil organic carbon and soil co/sub 2/ emission

    International Nuclear Information System (INIS)

    Abbas, F.

    2013-01-01

    SOC (Soil Organic Carbon) and soil CO/sub 2/ (Carbon Dioxide) emission are among the indicator of carbon sequestration and hence global climate change. Researchers in developed countries benefit from advance technologies to estimate C (Carbon) sequestration. However, access to the latest technologies has always been challenging in developing countries to conduct such estimates. This paper presents a simple and comprehensive approach for estimating SOC and soil CO/sub 2/ emission from arable- and forest soils. The approach includes various protocols that can be followed in laboratories of the research organizations or academic institutions equipped with basic research instruments and technology. The protocols involve soil sampling, sample analysis for selected properties, and the use of a worldwide tested Rothamsted carbon turnover model. With this approach, it is possible to quantify SOC and soil CO/sub 2/ emission over short- and long-term basis for global climate change assessment studies. (author)

  4. Soil aggregation and organic carbon of Oxisols under coffee in agroforestry systems

    Directory of Open Access Journals (Sweden)

    Gabriel Pinto Guimarães

    2014-02-01

    Full Text Available Intensive land use can lead to a loss of soil physical quality with negative impacts on soil aggregates, resistance to root penetration, porosity, and bulk density. Organic and agroforestry management systems can represent sustainable, well-balanced alternatives in the agroecosystem for promoting a greater input of organic matter than the conventional system. Based on the hypothesis that an increased input of organic matter improves soil physical quality, this study aimed to evaluate the impact of coffee production systems on soil physical properties in two Red-Yellow Oxisols (Latossolos Vermelho-Amarelos in the region of Caparaó, Espirito Santo, Brazil. On Farm 1, we evaluated the following systems: primary forest (Pf1, organic coffee (Org1 and conventional coffee (Con1. On Farm 2, we evaluated: secondary forest (Sf2, organic coffee intercropped with inga (Org/In2, organic coffee intercropped with leucaena and inga (Org/In/Le2, organic coffee intercropped with cedar (Org/Ced2 and unshaded conventional coffee (Con2. Soil samples were collected under the tree canopy from the 0-10, 10-20 and 20-40 cm soil layers. Under organic and agroforestry coffee management, soil aggregation was higher than under conventional coffee. In the agroforestry system, the degree of soil flocculation was 24 % higher, soil moisture was 80 % higher, and soil resistance to penetration was lower than in soil under conventional coffee management. The macroaggregates in the organic systems, Org/In2, Org/In/Le2, and Org/Ced2 contained, on average, 29.1, 40.1 and 34.7 g kg-1 organic carbon, respectively. These levels are higher than those found in the unshaded conventional system (Con2, with 20.2 g kg-1.

  5. Impact of soil organic matter on the distribution of polycyclic aromatic hydrocarbons (PAHs) in soils

    International Nuclear Information System (INIS)

    Yang, Y.; Zhang, N.; Xue, M.; Tao, S.

    2010-01-01

    The knowledge on the distribution of hydrophobic organic contaminants in soils can provide better understanding for their fate in the environment. In the present study, the n-butanol extraction and humic fractionation were applied to investigate the impact of SOM on the distribution of polycyclic aromatic hydrocarbons (PAHs). The results indicated that 80.5%-94.8% of the target PAHs could be extracted by n-butanol and 63.1%-94.6% of PAHs were associated with fulvic acid (FA). Concentrations of un-extracted PAHs increased significantly with the increasing soil organic matter (SOM), however, such an association was absent for the extractable fractions. The results suggested that the sequestration played a critical role in the accumulation of PAHs in soils. SOM also retarded the diffusion of PAHs into the humin fractions. It implied that sequestration in SOM was critical for PAH distribution in soils, while the properties of PAH compounds also had great influences. - Soil organic matter played an important role in the distribution of PAHs in soils through sequestration.

  6. Ground-fire effects on the composition of dissolved and total organic matter in forest floor and soil solutions from Scots pine forests in Germany: new insights from solid state 13C NMR analysis

    Science.gov (United States)

    Näthe, Kerstin; Michalzik, Beate; Levia, Delphis; Steffens, Markus

    2016-04-01

    Fires represent an ecosystem disturbance and are recognized to seriously pertubate the nutrient budgets of forested ecosystems. While the effects of fires on chemical, biological, and physical soil properties have been intensively studied, especially in Mediterranean areas and North America, few investigations examined the effects of fire-induced alterations in the water-bound fluxes and the chemical composition of dissolved and particulate organic carbon and nitrogen (DOC, POC, DN, PN). The exclusion of the particulate organic matter fraction (0.45 μm Independent from fire manipulation, the composition of TOM was generally less aromatic (aromaticity index [%] according to Hatcher et al., 1981) with values between 18 (FF) - 25% (B horizon) than the DOM fraction with 23 (FF) - 27% (B horizon). For DOM in FF solution, fire manipulation caused an increase in aromaticity from 23 to 27% compared to the control, due to an increase of the aryl-C and a decrease of the O-alkyl-C and alkyl-C signal. Fire effects were leveled out in the mineral soil. For TOM, fire effects became notable only in the A horizon, exhibiting a decrease in aromaticity from 22 to 18% compared to the control, due to increased O-alkyl-C and diminished aryl-C proportions. Compared to the control, fire only caused minor DOC release rates (events did not significantly enhance the proportion of POC and PN in the total C and N amounts exhibiting values between 10 and 20%. To fully understand the quality and amount of translocated organic C and N compounds within soils under both ambient as well as fire environments, dissolved and particulate size fractions need to be considered.

  7. Energy Transformations of Soil Organic Matter in a Changing World

    Science.gov (United States)

    Herrmann, A. M.; Coucheney, E.; Grice, S. M.; Ritz, K.; Harris, J.

    2011-12-01

    The role of soils in governing the terrestrial carbon balance is acknowledged as being important but remains poorly understood within the context of climate change. Soils exchange energy with their surroundings and are therefore open systems thermodynamically, but little is known how energy transformations of decomposition processes are affected by temperature. Soil organic matter and the soil biomass can be conceptualised as analogous to the 'fuel' and 'biological engine' of the earth, respectively, and are pivotal in driving the belowground carbon cycle. Thermodynamic principles of soil organic matter decomposition were evaluated by means of isothermal microcalorimetry (TAM Air, TA Instruments, Sollentuna Sweden: (i) Mineral forest soils from the Flakaliden long-term nitrogen fertilisation experiment (Sweden) were amended with a range of different substrates representing structurally simple to complex, ecologically pertinent organic matter and heat signatures were determined at temperatures between 5 and 25°C. (ii) Thermodynamic and resource-use efficiencies of the biomass were determined in arable soils which received contrasting long-term management regimes with respect to organic matter and nitrogen since 1956. The work showed that (i) structurally labile components have higher activation energy and temperature dependence than structurally more complex organic components. This is, however, in contrast to the thermodynamic argument which suggests the opposite that reactions metabolising structurally complex, aromatic components have higher temperature dependence than reactions metabolising structurally more labile components. (ii) Microbial communities exposed to long-term stress by heavy metal and low pH were less thermodynamic efficient and showed a decrease in resource-use efficiency in comparison with conventional input regimes. Differences in efficiencies were mirrored in both the phenotypic and functional profiles of the communities. We will present our

  8. Cosorption study of organic pollutants and dissolved organic matter in a soil

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Cespedes, F. [Department of Inorganic Chemistry, University of Almeria, La Canada de San Urbano s/n, 04120 Almeria (Spain); Fernandez-Perez, M. [Department of Inorganic Chemistry, University of Almeria, La Canada de San Urbano s/n, 04120 Almeria (Spain)]. E-mail: mfernand@ual.es; Villafranca-Sanchez, M. [Department of Inorganic Chemistry, University of Almeria, La Canada de San Urbano s/n, 04120 Almeria (Spain); Gonzalez-Pradas, E. [Department of Inorganic Chemistry, University of Almeria, La Canada de San Urbano s/n, 04120 Almeria (Spain)

    2006-08-15

    In this study we have evaluated the effects of dissolved organic matter (DOM) on sorption of imidacloprid, 3,4-dichloroaniline (3,4-DCA) and 4-bromoaniline (4-BA) on a typical calcareous soil (Luvic Xerosol) from south-eastern Spain. Two different types of DOM were used, that is to say, dissolved natural organic matter extracts from a commercial peat (DNOM) and a high-purity tannic acid (TA) solution. The experiments were carried out in a 0.01 M CaCl{sub 2} aqueous medium at 25 deg. C. The results indicated that the presence of both DNOM and TA, over a concentration range of 15-100 mg L{sup -1}, produced an increase in the amount of 3,4-DCA and 4-BA sorbed and a decrease in the amount of imidacloprid retained on the soil studied. A modified distribution coefficient, K {sub doc}, has been proposed as a safer parameter for soil sorption predictions of organic pollutants and it could be of help to model the fate of these in the environment. - Cosorption of organic pollutants and DOM.

  9. Cosorption study of organic pollutants and dissolved organic matter in a soil

    International Nuclear Information System (INIS)

    Flores-Cespedes, F.; Fernandez-Perez, M.; Villafranca-Sanchez, M.; Gonzalez-Pradas, E.

    2006-01-01

    In this study we have evaluated the effects of dissolved organic matter (DOM) on sorption of imidacloprid, 3,4-dichloroaniline (3,4-DCA) and 4-bromoaniline (4-BA) on a typical calcareous soil (Luvic Xerosol) from south-eastern Spain. Two different types of DOM were used, that is to say, dissolved natural organic matter extracts from a commercial peat (DNOM) and a high-purity tannic acid (TA) solution. The experiments were carried out in a 0.01 M CaCl 2 aqueous medium at 25 deg. C. The results indicated that the presence of both DNOM and TA, over a concentration range of 15-100 mg L -1 , produced an increase in the amount of 3,4-DCA and 4-BA sorbed and a decrease in the amount of imidacloprid retained on the soil studied. A modified distribution coefficient, K doc , has been proposed as a safer parameter for soil sorption predictions of organic pollutants and it could be of help to model the fate of these in the environment. - Cosorption of organic pollutants and DOM

  10. The effects of organic matter-mineral interactions and organic matter chemistry on diuron sorption across a diverse range of soils.

    Science.gov (United States)

    Smernik, Ronald J; Kookana, Rai S

    2015-01-01

    Sorption of non-ionic organic compounds to soil is usually expressed as the carbon-normalized partition coefficient (KOC), because it is assumed that the main factor that influences the amount sorbed is the organic carbon content of the soil. However, KOC can vary by a factor of at least ten across a range of soils. We investigated two potential causes of variation in diuron KOC - organic matter-mineral interactions and organic matter chemistry - for a diverse set of 34 soils from Sri Lanka, representing a wide range of soil types. Treatment with hydrofluoric acid (HF-treatment) was used to concentrate soil organic matter. HF-treatment increased KOC for the majority of soils (average factor 2.4). We attribute this increase to the blocking of organic matter sorption sites in the whole soils by minerals. There was no significant correlation between KOC for the whole soils and KOC for the HF-treated soils, indicating that the importance of organic matter-mineral interactions varied greatly amongst these soils. There was as much variation in KOC across the HF-treated soils as there was across the whole soils, indicating that the nature of soil organic matter is also an important contributor to KOC variability. Organic matter chemistry, determined by solid-state (13)C nuclear magnetic resonance (NMR) spectroscopy, was correlated with KOC for the HF-treated soils. In particular, KOC increased with the aromatic C content (R=0.64, p=1×10(-6)), and decreased with O-alkyl C (R=-0.32, p=0.03) and alkyl C (R=-0.41, p=0.004) content. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Effect of long-term industrial waste effluent pollution on soil enzyme activities and bacterial community composition.

    Science.gov (United States)

    Subrahmanyam, Gangavarapu; Shen, Ju-Pei; Liu, Yu-Rong; Archana, Gattupalli; Zhang, Li-Mei

    2016-02-01

    Although numerous studies have addressed the influence of exogenous pollutants on microorganisms, the effect of long-term industrial waste effluent (IWE) pollution on the activity and diversity of soil bacteria was still unclear. Three soil samples characterized as uncontaminated (R1), moderately contaminated (R2), and highly contaminated (R3) receiving mixed organic and heavy metal pollutants for more than 20 years through IWE were collected along the Mahi River basin, Gujarat, western India. Basal soil respiration and in situ enzyme activities indicated an apparent deleterious effect of IWE on microbial activity and soil function. Community composition profiling of soil bacteria using 16S rRNA gene amplification and denaturing gradient gel electrophoresis (DGGE) method indicated an apparent bacterial community shift in the IWE-affected soils. Cloning and sequencing of DGGE bands revealed that the dominated bacterial phyla in polluted soil were affiliated with Firmicutes, Acidobacteria, and Actinobacteria, indicating that these bacterial phyla may have a high tolerance to pollutants. We suggested that specific bacterial phyla along with soil enzyme activities could be used as relevant biological indicators for long-term pollution assessment on soil quality. Graphical Abstract Bacterial community profiling and soil enzyme activities in long-term industrial waste effluent polluted soils.

  12. Parameter Sensitivity Analysis on Deformation of Composite Soil-Nailed Wall Using Artificial Neural Networks and Orthogonal Experiment

    Directory of Open Access Journals (Sweden)

    Jianbin Hao

    2014-01-01

    Full Text Available Based on the back-propagation algorithm of artificial neural networks (ANNs, this paper establishes an intelligent model, which is used to predict the maximum lateral displacement of composite soil-nailed wall. Some parameters, such as soil cohesive strength, soil friction angle, prestress of anchor cable, soil-nail spacing, soil-nail diameter, soil-nail length, and other factors, are considered in the model. Combined with the in situ test data of composite soil-nail wall reinforcement engineering, the network is trained and the errors are analyzed. Thus it is demonstrated that the method is applicable and feasible in predicting lateral displacement of excavation retained by composite soil-nailed wall. Extended calculations are conducted by using the well-trained intelligent forecast model. Through application of orthogonal table test theory, 25 sets of tests are designed to analyze the sensitivity of factors affecting the maximum lateral displacement of composite soil-nailing wall. The results show that the sensitivity of factors affecting the maximum lateral displacement of composite soil nailing wall, in a descending order, are prestress of anchor cable, soil friction angle, soil cohesion strength, soil-nail spacing, soil-nail length, and soil-nail diameter. The results can provide important reference for the same reinforcement engineering.

  13. Effects of short-chain chlorinated paraffins on soil organisms.

    Science.gov (United States)

    Bezchlebová, Jitka; Cernohlávková, Jitka; Kobeticová, Klára; Lána, Jan; Sochová, Ivana; Hofman, Jakub

    2007-06-01

    Despite the fact that chlorinated paraffins have been produced in relatively large amounts, and high concentrations have been found in sewage sludge applied to soils, there is little information on their concentrations in soils and the effect on soil organisms. The aim of this study was to investigate the toxicity of chlorinated paraffins in soils. The effects of short-chain chlorinated paraffins (64% chlorine content) on invertebrates (Eisenia fetida, Folsomia candida, Enchytraeus albidus, Enchytraeus crypticus, Caenorhabditis elegans) and substrate-induced respiration of indigenous microorganisms were studied. Differences were found in the sensitivity of the tested organisms to short-chain chlorinated paraffins. F. candida was identified as the most sensitive organism with LC(50) and EC(50) values of 5733 and 1230 mg/kg, respectively. Toxicity results were compared with available studies and the predicted no effect concentration (PNEC) of 5.28 mg/kg was estimated for the soil environment, based on our data.

  14. Effects of Rice Straw and Its Biochar Addition on Soil Labile Carbon and Soil Organic Carbon

    Institute of Scientific and Technical Information of China (English)

    YIN Yun-feng; HE Xin-hua; GAO Ren; MA Hong-liang; YANG Yu-sheng

    2014-01-01

    Whether the biochar amendment could affect soil organic matter (SOM) turnover and hence soil carbon (C) stock remains poorly understood. Effects of the addition of 13C-labelled rice straw or its pyrolysed biochar at 250 or 350°C to a sugarcane soil (Ferrosol) on soil labile C (dissolved organic C, DOC;microbial biomass C, MBC;and mineralizable C, MC) and soil organic C (SOC) were investigated after 112 d of laboratory incubation at 25°C. Four treatments were examined as (1) the control soil without amendment (Soil);(2) soil plus 13C-labelled rice straw (Soil+Straw);(3) soil plus 250°C biochar (Soil+B250) and (4) soil plus 350°C biochar (Soil+B350). Compared to un-pyrolysed straw, biochars generally had an increased aryl C, carboxyl C, C and nitrogen concentrations, a decreased O-alkyl C and C:N ratio, but similar alkyl C and d13C (1 742-1 877‰). Among treatments, signiifcant higher DOC, MBC and MC derived from the new C (straw or biochar) ranked as Soil+Straw>Soil+B250>Soil+B350, whilst signiifcant higher SOC from the new C as Soil+B250>Soil+Straw≈Soil+B350. Compared to Soil, DOC and MBC derived from the native soil were decreased under straw or biochar addition, whilst MC from the native soil was increased under straw addition but decreased under biochar addition. Meanwhile, native SOC was similar among the treatments, irrespective of the straw or biochar addition. Compared to Soil, signiifcant higher total DOC and total MBC were under Soil+Straw, but not under Soil+B250 and Soil+B350, whilst signiifcant higher total MC and total SOC were under straw or biochar addition, except for MC under Soil+B350. Our results demonstrated that the application of biochar to soil may be an appropriate management practice for increasing soil C storage.

  15. Sorption of Cu and Zn in low organic matter-soils as influenced by soil properties and by the degree of soil weathering.

    Science.gov (United States)

    Antoniadis, V; Golia, E E

    2015-11-01

    Copper and Zn sorption and desorption, among other factors, depend on soil pH, but in soils with different degree of weathering the role of other soil properties (e.g., oxides content and the level of their crystallinity) has not been thoroughly examined. We conducted batch sorption and desorption tests using 21 low-organic C soils that belonged to the soil orders of Entisols, newly developed soils, Inceptisols, and Alfisols, the most weathered soils. Zinc sorption was lower than that of Cu, and its desorption faster, confirming that it is a highly mobile metal. Alfisols had the weaker affinity for metals, due to the lower soil pH typical of this soil order, but also due to the low reactivity colloids they contained. Correlation analyses showed that Fe oxides in Alfisols increased metal release from soils, while they decreased metal desorption from Entisols. We conclude that in low organic matter-content soils, where the protective role of organic colloids is not to be expected, high soil pH alone is not sufficient to protect against metal contamination, but the degree of soil weathering is also important, due to the dominant role of other mineral phases (here, Fe oxides). Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. The impact of mineral composition on compressibility of saturated soils

    OpenAIRE

    Dolinar, Bojana

    2012-01-01

    This article analyses the impact of soils` mineral composition on their compressibility. Physical and chemical properties of minerals which influence the quantity of intergrain water in soils and, consequently, the compressibility of soils are established by considering the previous theoretical findings. Test results obtained on artificially prepared samples are used to determine the analytical relationship between the water content and stress state, depending on the mineralogical properties ...

  17. Interactive effects of elevated CO2 and nitrogen deposition on fatty acid molecular and isotope composition of above- and belowground tree biomass and forest soil fractions.

    Science.gov (United States)

    Griepentrog, Marco; Eglinton, Timothy I; Hagedorn, Frank; Schmidt, Michael W I; Wiesenberg, Guido L B

    2015-01-01

    Atmospheric carbon dioxide (CO2) and reactive nitrogen (N) concentrations have been increasing due to human activities and impact the global carbon (C) cycle by affecting plant photosynthesis and decomposition processes in soil. Large amounts of C are stored in plants and soils, but the mechanisms behind the stabilization of plant- and microbial-derived organic matter (OM) in soils are still under debate and it is not clear how N deposition affects soil OM dynamics. Here, we studied the effects of 4 years of elevated (13C-depleted) CO2 and N deposition in forest ecosystems established in open-top chambers on composition and turnover of fatty acids (FAs) in plants and soils. FAs served as biomarkers for plant- and microbial-derived OM in soil density fractions. We analyzed above- and belowground plant biomass of beech and spruce trees as well as soil density fractions for the total organic C and FA molecular and isotope (δ13C) composition. FAs did not accumulate relative to total organic C in fine mineral fractions, showing that FAs are not effectively stabilized by association with soil minerals. The δ13C values of FAs in plant biomass increased under high N deposition. However, the N effect was only apparent under elevated CO2 suggesting a N limitation of the system. In soil fractions, only isotope compositions of short-chain FAs (C16+18) were affected. Fractions of 'new' (experimental-derived) FAs were calculated using isotope depletion in elevated CO2 plots and decreased from free light to fine mineral fractions. 'New' FAs were higher in short-chain compared to long-chain FAs (C20-30), indicating a faster turnover of short-chain compared to long-chain FAs. Increased N deposition did not significantly affect the quantity of 'new' FAs in soil fractions, but showed a tendency of increased amounts of 'old' (pre-experimental) C suggesting that decomposition of 'old' C is retarded by high N inputs. © 2014 John Wiley & Sons Ltd.

  18. Analysis of Seasonal Soil Organic Carbon Content at Bukit Jeriau Forest, Fraser Hill, Pahang

    International Nuclear Information System (INIS)

    Ahmad Adnan Mohamed; Ahmad Adnan Mohamed; Sahibin Abd Rahim; David Allan Aitman; Mohd Khairul Amri Kamarudin; Mohd Khairul Amri Kamarudin

    2016-01-01

    Soil carbon is the carbon held within the soil, primarily in association with its organic content. The total soil organic carbon study was determined in a plot at Bukit Jeriau forest in Bukit Fraser, Pahang, Malaysia. The aim of this study is to determine the changing of soil organic carbon between wet season and dry season. Soil organic carbon was fined out using titrimetric determination. The soil organic carbon content in wet season is 223.24 t/ ha while dry season is 217.90 t/ ha. The soil pH range in wet season is between 4.32 to 4.45 and in dry season in 3.95 to 4.08 which is considered acidic. Correlation analysis showed that soil organic carbon value is influenced by pH value and climate. Correlation analysis between clay and soil organic carbon with depth showed positively significant differences and clay are very much influenced soil organic carbon content. Correlation analysis between electrical conductivity and soil organic carbon content showed negative significantly difference on wet season and positively significant different in dry season. (author)

  19. Determination of solute organic concentration in contaminated soils using a chemical-equilibrium soil column system

    DEFF Research Database (Denmark)

    Gamst, Jesper; Kjeldsen, Peter; Christensen, Thomas Højlund

    2007-01-01

    using two soils with different content of organic carbon (f(oc) of 1.5 and 6.5%, respectively). A quadruple blind test of the ER-V system using glass beads in stead of soil showed an acceptable recovery (65-85%) of all of the 11 VOCs tested. Only for the most volatile compound (heptane, K-H similar...... to 80) an unacceptable recovery was found (9%). The contact time needed for obtaining chemical equilibrium was tested in the ER-H system by performing five test with different duration (1, 2, 4, 7 and 19 days) using the low organic carbon soil. Seven days of contact time appeared sufficient...... for determination of solute concentration in a contaminated soil were developed; (1) a chemical Equilibrium and Recirculation column test for Volatile organic chemicals (ER-V) and (2) a chemical Equilibrium and Recirculation column test for Hydrophobic organic chemicals (ER-H). The two test systems were evaluated...

  20. Bulk soil and maize rhizosphere resistance genes, mobile genetic elements and microbial communities are differently impacted by organic and inorganic fertilization

    DEFF Research Database (Denmark)

    Wolters, Birgit; Jacquiod, Samuel Jehan Auguste; Sørensen, Søren Johannes

    2018-01-01

    Organic soil fertilizers, such as livestock manure and biogas digestate, frequently contain bacteria carrying resistance genes (RGs) to antimicrobial substances and mobile genetic elements (MGEs). The effects of different fertilizers (inorganic, manure, digestate) on RG and MGE abundance...... and microbial community composition were investigated in a field plot experiment. The relative abundances of RGs [sul1, sul2, tet(A), tet(M), tet(Q), tet(W), qacEΔ1/qacE] and MGEs [intI1, intI2, IncP-1, IncP-1ε and LowGC plasmids] in total community (TC)-DNA from organic fertilizers, bulk soil and maize......, integrons and few genera affiliated to Bacteroidetes and Firmicutes in bulk soil, while digestate increased sul2, tet(W) and intI2. At harvest, treatment effects vanished in bulk soil. However, organic fertilizer effects were still detectable in the rhizosphere for RGs [manure: intI1, sul1; digestate: tet...

  1. Sorption of Emerging Organic Wastewater Contaminants to Four Soils

    Directory of Open Access Journals (Sweden)

    Sarah Roberts

    2014-04-01

    Full Text Available Conventional onsite wastewater treatment system design relies on a septic tank and soil treatment unit (STU for treatment of wastewater and integration of the final effluent into the environment. Organic water contaminants (OWCs, chemicals found in pharmaceutical drugs, detergents, surfactants, and other personal care and cleaning products, have been observed in septic tank effluent and the environment. Sorption of OWC mass to soil is a key mechanism in the removal and retardation of many of these chemicals in effluent as it travels through an STU. The primary purpose of this study was to investigate the relationship between the fraction of organic carbon of soil and the equilibrium sorption partitioning coefficient of a selected group of relevant and diverse OWCs. A secondary goal is to evaluate current methods of modeling the sorption of selected OWCs in soil. Five point Freundlich isotherms were constructed from equilibrium sorption batch tests for target OWCs with four different soils. For soils with organic carbon fraction between 0.021 and 0.054, Kd values were calculated between 60 and 185 for 4-nonylphenol, 75 to 260 for triclosan, 115 to 270 for bisphenol-A, 3 to 255 for 17β-estradiol, 40 to 55 for 17α-ethynylestradiol, and 28 to 70 for estrone. An empirically derived, direct relationship between foc and Kd may be a useful approach to estimating sorption for a soil based on organic carbon content.

  2. Soil-ecological risks for soil degradation estimation

    Science.gov (United States)

    Trifonova, Tatiana; Shirkin, Leonid; Kust, German; Andreeva, Olga

    2016-04-01

    Soil degradation includes the processes of soil properties and quality worsening, primarily from the point of view of their productivity and decrease of ecosystem services quality. Complete soil cover destruction and/or functioning termination of soil forms of organic life are considered as extreme stages of soil degradation, and for the fragile ecosystems they are normally considered in the network of their desertification, land degradation and droughts /DLDD/ concept. Block-model of ecotoxic effects, generating soil and ecosystem degradation, has been developed as a result of the long-term field and laboratory research of sod-podzol soils, contaminated with waste, containing heavy metals. The model highlights soil degradation mechanisms, caused by direct and indirect impact of ecotoxicants on "phytocenosis- soil" system and their combination, frequently causing synergistic effect. The sequence of occurring changes here can be formalized as a theory of change (succession of interrelated events). Several stages are distinguished here - from heavy metals leaching (releasing) in waste and their migration downward the soil profile to phytoproductivity decrease and certain phytocenosis composition changes. Phytoproductivity decrease leads to the reduction of cellulose content introduced into the soil. The described feedback mechanism acts as a factor of sod-podzolic soil self-purification and stability. It has been shown, that using phytomass productivity index, integrally reflecting the worsening of soil properties complex, it is possible to solve the problems dealing with the dose-reflecting reactions creation and determination of critical levels of load for phytocenosis and corresponding soil-ecological risks. Soil-ecological risk in "phytocenosis- soil" system means probable negative changes and the loss of some ecosystem functions during the transformation process of dead organic substance energy for the new biomass composition. Soil-ecological risks estimation is

  3. Potential for Increasing Soil Nutrient Availability via Soil Organic Matter Improvement Using Pseudo Panel Data

    NARCIS (Netherlands)

    Chavez Clemente, M.D.; Berentsen, P.B.M.; Oenema, O.; Oude Lansink, A.G.J.M.

    2014-01-01

    Fixed and random effect models were applied to a pseudo-panel data built of soil analysis reports from tobacco farms to analyze relationships between soil characteristics like soil organic matter (SOM) and soil nitrogen (N), phosphorous (P) and potassium (K) and to explore the potential for

  4. Soils and organic sediments

    International Nuclear Information System (INIS)

    Head, M.J.

    1999-01-01

    The organic component of soils is basically made up of substances of an individual nature (fats, waxes, resins, proteins, tannic substances, and many others), and humic substances (Kononova, 1966). These are complex polymers formed from breakdown products of the chemical and biological degradation of plant and animal residues. They are dark coloured, acidic, predominantly aromatic compounds ranging in molecular weight from less than one thousand to tens of thousands (Schnitzer, 1977). They can be partitioned into three main fractions:(i) Humic acid, which is soluble in dilute alkaline solution, but can be precipitated by acidification of the alkaline extract.(ii) Fulvic acid, which is soluble in alkaline solution, but is also soluble on acidification.(iii) Humin that cannot be extracted from the soil or sediment by dilute acid or alkaline solutions. It has mostly been assumed that the humic and fulvic acid components of the soil are part of the mobile, or 'active' component, and the humin component is part of the 'passive' component. Other types of organic sediments are likely to contain chemical breakdown products of plant material, plant fragments and material brought in from outside sources. The outside material can be contemporaneous with sediment deposition, can be older material, or younger material incorporated into the sediment long after deposition. Recognition of 'foreign' material is essential for dating, but is not an easy task. Examples of separation techniques for humic and non humic components are evaluated for their efficiency

  5. Concentrations and geographic distribution of selected organic pollutants in Scottish surface soils

    International Nuclear Information System (INIS)

    Rhind, S.M.; Kyle, C.E.; Kerr, C.; Osprey, M.; Zhang, Z.L.; Duff, E.I.; Lilly, A.; Nolan, A.; Hudson, G.; Towers, W.; Bell, J.; Coull, M.; McKenzie, C.

    2013-01-01

    Concentrations of selected persistent organic pollutants (POPs) representing three chemical classes (polycyclic aromatic hydrocarbons (PAH), polybrominated diphenyl ethers (PBDE) and polychlorinated biphenyls (PCB) and the organic pollutant diethylhexyl phthalate (DEHP), were determined in surface soil samples (0–5 cm) collected at 20 km grid intersects throughout Scotland over a three-year period. Detectable amounts of all chemical classes and most individual congeners were present in all samples. There were no consistent effects of soil or vegetation type, soil carbon content, pH, altitude or distance from centres of population on concentrations which exhibited extreme variation, even in adjacent samples. It is concluded that soil POPs and DEHP concentrations and associated rates of animal and human exposure were highly variable, influenced by multiple, interacting factors, and not clearly related to local sources but possibly related to wet atmospheric deposition and the organic carbon content of the soil. -- Highlights: •Concentrations of selected organic pollutants in Scottish soils were determined. •Concentrations were highly variable. •There were few effects of soil or vegetation type, soil carbon, pH or altitude. •Distance from cities was not an important determinant of concentrations. •Atmospheric deposition and soil organic carbon content may affect concentrations. -- Soil concentrations of anthropogenic persistent organic pollutants are not clearly related to soil type or pH, vegetation, altitude, or distance from pollutant sources

  6. Theory study of global density influence and soils chemical composition at neutron probes response

    International Nuclear Information System (INIS)

    Crispino, M.L.

    1980-06-01

    Three energy group diffusion theory is applied to calculate the thermal neutron flux through a soil-water mixture at the neutron source. The soils studies are taken from two horizons of different composition, of a representative soil of the Litoral-Mata Zone of Pernambuco State. The thermal flux is obtained taking into consideration increasing values of the water volume percent, H, and the bulk density of the soil. The cross-sections of the mixture are calculated from the chemical composition of the soils. (author)

  7. Sorption interactions of organic compounds with soils affected by agricultural olive mill wastewater.

    Science.gov (United States)

    Keren, Yonatan; Borisover, Mikhail; Bukhanovsky, Nadezhda

    2015-11-01

    The organic compound-soil interactions may be strongly influenced by changes in soil organic matter (OM) which affects the environmental fate of multiple organic pollutants. The soil OM changes may be caused by land disposal of various OM-containing wastes. One unique type of OM-rich waste is olive mill-related wastewater (OMW) characterized by high levels of OM, the presence of fatty aliphatics and polyphenolic aromatics. The systematic data on effects of the land-applied OMW on organic compound-soil interactions is lacking. Therefore, aqueous sorption of simazine and diuron, two herbicides, was examined in batch experiments onto three soils, including untreated and OMW-affected samples. Typically, the organic compound-soil interactions increased following the prior land application of OMW. This increase is associated with the changes in sorption mechanisms and cannot be attributed solely to the increase in soil organic carbon content. A novel observation is that the OMW application changes the soil-sorbent matrix in such a way that the solute uptake may become cooperative or the existing ability of a soil sorbent to cooperatively sorb organic molecules from water may become characterized by a larger affinity. The remarkable finding of this study was that in some cases a cooperative uptake of organic molecules by soils makes itself evident in distinct sigmoidal sorption isotherms rarely observed in soil sorption of non-ionized organic compounds; the cooperative herbicide-soil interactions may be characterized by the Hill model coefficients. However, no single trend was found for the effect of applied OMW on the mechanisms of organic compound-soil interactions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Mineralogical composition changes of postagrogenic soils under different plant communities.

    Science.gov (United States)

    Churilin, Nikita; Chizhikova, Natalia; Varlamov, Evgheni; Churilina, Alexandra

    2017-04-01

    Plant communities play the leading role in transformation of soil. The need of studying former arable lands increases due to large number of abandoned lands in Russia. It is necessary to study mineralogical composition of soils involved into natural processes to understand the trends of their development after agricultural activities in the past. The aim of the study is to identify changes in mineralogical composition of soils under the influence of different plant communities. Soils were sampled in the south of Arkhangelsk region, Ustyansky district, near Akichkin Pochinok village. Soils are formed on clay moraine of Moscow glaciation. Soil profiles were dug on interfluve. We selected 4 plant communities on different stages of succession: upland meadow with domination of sod grasses (Phleum pratense, Agrostis tenuis), 16-year-old birch forest where dominants are herbaceous plants such as Poa sp., Chamerion angustiflium, Agrostis tenuis, 16-year-old spruce forest with no herbaceous vegetation and 70-year-old bilberry spruce forest with domination of Vaccinium myrtillus and Vaccinium vitis-idaea. To separate soil fractions mineral content. We noticed a clear differentiation of studied soils both in the content of fraction and composition of minerals. Mineralogical composition and major mineral phases correlation of profiles under 70 years and 16 years of spruce forests are different. Mineralogical content in upper part of profile under the young spruce is more differentiated than in old spruce forest: the amount of quartz and kaolinite increases in upper horizon, although in this case the overall pattern of profile formation of clay material during podzolization remains unchanged. There is more substantial desilting under the birch forest, compared with profile under the spruce of same age within top 50 cm. Under the meadow vegetation we've discovered differentiation in mineral composition. Upper horizons contain smectite phase and differ from the underlying

  9. Influence of dissolved organic matter and manganese oxides on metal speciation in soil solution: A modelling approach.

    Science.gov (United States)

    Schneider, Arnaud R; Ponthieu, Marie; Cancès, Benjamin; Conreux, Alexandra; Morvan, Xavier; Gommeaux, Maxime; Marin, Béatrice; Benedetti, Marc F

    2016-06-01

    Trace element (TE) speciation modelling in soil solution is controlled by the assumptions made about the soil solution composition. To evaluate this influence, different assumptions using Visual MINTEQ were tested and compared to measurements of free TE concentrations. The soil column Donnan membrane technique (SC-DMT) was used to estimate the free TE (Cd, Cu, Ni, Pb and Zn) concentrations in six acidic soil solutions. A batch technique using DAX-8 resin was used to fractionate the dissolved organic matter (DOM) into four fractions: humic acids (HA), fulvic acids (FA), hydrophilic acids (Hy) and hydrophobic neutral organic matter (HON). To model TE speciation, particular attention was focused on the hydrous manganese oxides (HMO) and the Hy fraction, ligands not considered in most of the TE speciation modelling studies in soil solution. In this work, the model predictions of free ion activities agree with the experimental results. The knowledge of the FA fraction seems to be very useful, especially in the case of high DOM content, for more accurately representing experimental data. Finally, the role of the manganese oxides and of the Hy fraction on TE speciation was identified and, depending on the physicochemical conditions of the soil solution, should be considered in future studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Organic vs. conventional grassland management: do (15)N and (13)C isotopic signatures of hay and soil samples differ?

    Science.gov (United States)

    Klaus, Valentin H; Hölzel, Norbert; Prati, Daniel; Schmitt, Barbara; Schöning, Ingo; Schrumpf, Marion; Fischer, Markus; Kleinebecker, Till

    2013-01-01

    Distinguishing organic and conventional products is a major issue of food security and authenticity. Previous studies successfully used stable isotopes to separate organic and conventional products, but up to now, this approach was not tested for organic grassland hay and soil. Moreover, isotopic abundances could be a powerful tool to elucidate differences in ecosystem functioning and driving mechanisms of element cycling in organic and conventional management systems. Here, we studied the δ(15)N and δ(13)C isotopic composition of soil and hay samples of 21 organic and 34 conventional grasslands in two German regions. We also used Δδ(15)N (δ(15)N plant - δ(15)N soil) to characterize nitrogen dynamics. In order to detect temporal trends, isotopic abundances in organic grasslands were related to the time since certification. Furthermore, discriminant analysis was used to test whether the respective management type can be deduced from observed isotopic abundances. Isotopic analyses revealed no significant differences in δ(13)C in hay and δ(15)N in both soil and hay between management types, but showed that δ(13)C abundances were significantly lower in soil of organic compared to conventional grasslands. Δδ(15)N values implied that management types did not substantially differ in nitrogen cycling. Only δ(13)C in soil and hay showed significant negative relationships with the time since certification. Thus, our result suggest that organic grasslands suffered less from drought stress compared to conventional grasslands most likely due to a benefit of higher plant species richness, as previously shown by manipulative biodiversity experiments. Finally, it was possible to correctly classify about two third of the samples according to their management using isotopic abundances in soil and hay. However, as more than half of the organic samples were incorrectly classified, we infer that more research is needed to improve this approach before it can be efficiently

  11. Organic vs. Conventional Grassland Management: Do 15N and 13C Isotopic Signatures of Hay and Soil Samples Differ?

    Science.gov (United States)

    Klaus, Valentin H.; Hölzel, Norbert; Prati, Daniel; Schmitt, Barbara; Schöning, Ingo; Schrumpf, Marion; Fischer, Markus; Kleinebecker, Till

    2013-01-01

    Distinguishing organic and conventional products is a major issue of food security and authenticity. Previous studies successfully used stable isotopes to separate organic and conventional products, but up to now, this approach was not tested for organic grassland hay and soil. Moreover, isotopic abundances could be a powerful tool to elucidate differences in ecosystem functioning and driving mechanisms of element cycling in organic and conventional management systems. Here, we studied the δ15N and δ13C isotopic composition of soil and hay samples of 21 organic and 34 conventional grasslands in two German regions. We also used Δδ15N (δ15N plant - δ15N soil) to characterize nitrogen dynamics. In order to detect temporal trends, isotopic abundances in organic grasslands were related to the time since certification. Furthermore, discriminant analysis was used to test whether the respective management type can be deduced from observed isotopic abundances. Isotopic analyses revealed no significant differences in δ13C in hay and δ15N in both soil and hay between management types, but showed that δ13C abundances were significantly lower in soil of organic compared to conventional grasslands. Δδ15N values implied that management types did not substantially differ in nitrogen cycling. Only δ13C in soil and hay showed significant negative relationships with the time since certification. Thus, our result suggest that organic grasslands suffered less from drought stress compared to conventional grasslands most likely due to a benefit of higher plant species richness, as previously shown by manipulative biodiversity experiments. Finally, it was possible to correctly classify about two third of the samples according to their management using isotopic abundances in soil and hay. However, as more than half of the organic samples were incorrectly classified, we infer that more research is needed to improve this approach before it can be efficiently used in practice

  12. Dissolved organic carbon (DOC) in soil extracts investigated by FT-ICR-MS

    Science.gov (United States)

    Hofmann, D.; Steffen, D.; Jablonowski, N. D.; Burauel, P.

    2012-04-01

    . The characteristics of measured DOM mass spectra were demonstrated. Furthermore, an algorithm to compute all chemically relevant C,H,O-, C,H,(O,S),N- as well as C,H,(O),S molecular compositions, designed and exercised by ourself using Scilab routines, was used for entire structure elucidation. Various methods for data evaluation of such an amount of peaks are applied to describe the characteristics of DOC. The van Krevelen diagram is widely used to classify the DOC compounds regarding polarity and aromaticity, whereas the Kendrick diagram allow to identify ions with elemental formulas that differ only in CH2, and molecular formulas with similar Kendrick Mass Defect (KMD) can be sorted by nominal mass series. Both kind of diagrams were developed and results are discussed together with the findings of ETD, MBT, and metabolites after soil drying and rewetting. Overall, the results suggest that intermittent soil drying and rewetting alters the disaggregation of soil aggregates, resulting in a release of entrapped organic carbon as well as pesticide molecules.

  13. Chemical and geotechnical assessment of low organic foundation soils across the coastal area of Southwestern Nigeria

    Science.gov (United States)

    Adebisi, N. O.; Osammor, J.; Oluwafemi, O. S.

    2018-04-01

    Pressure on land use has caused great site development along the coastal area of south western Nigeria. However, research works for the purpose of evaluating appropriate depths of foundations in the area were without cognizance of engineering challenges that may ensue as a result of the organic content, and associated factors of the soils. This paper evaluates the compositional effects of the soils on foundation materials, and a phenomenological model of compressibility of fines during design and construction of problem-free foundations in the area. Thirty (30) disturbed soils were analysed for moisture content, grain size distribution, consistency limits, chloride, pH and sulphate, while the oedometer consolidation test was carried out on another 30 undisturbed soils. The stratigraphic sequence in the profile comprises medium dense to coarse grained silty clayey sand to 16.80 m depth, below loose grey organic silty clayey sand from the surface. Results show in most cases, that the foundation soils contain insignificant percentages (0.95-5.8%) of organic solids. Moisture content (44-70%), chloride (74.9 ppm), sulphate (420 ppm) ions concentration and pH (8.96) could enhance the corrosive potential of the soils. It is recommended that Portland cement concrete will be suitable in the environment. Foundation settlement with respect to surface area (0.028≤ mv ≤ 0.434m2MN-1 at 200 kNm-2; 0.038mv ≤ 0.776m2MN-1 at 400 kNm-2; 0.038≤ mv ≤ 0.879m2MN-1 at 800 kNm-2) ranges from low to medium compressibility with respect to consolidation pressure. Therefore, footings load need be spread over the soils, and foundation design need be based on site-specific soil information.

  14. Sequestration of organochlorine pesticides in soils of distinct organic carbon content

    International Nuclear Information System (INIS)

    Zhang Na; Yang Yu; Tao Shu; Liu Yan; Shi Kelu

    2011-01-01

    In the present study, five soil samples with organic carbon contents ranging from 0.23% to 7.1% and aged with technical dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) for 15 months were incubated in a sealed chamber to investigate the dynamic changes of the OCP residues. The residues in the soils decreased over the incubation period and finally reached a plateau. Regression analysis showed that degradable fractions of OCPs were negatively correlated with soil organic carbon (SOC) except for α-HCH, while no correlation was found between degradation rate and SOC, which demonstrated that SOC content determines the OCP sequestration fraction in soil. Analysis of the ratio of DDT and its primary metabolites showed that, since it depends on differential sequestration among them, magnitude of (p,p'-DDE + p,p'-DDD)/p,p'-DDT is not a reliable criterion for the identification of new DDT sources. - Research highlights: → Soil organic carbon content determines the OCP sequestration fraction in soil. → Magnitude of (p,p'-DDE + p,p'-DDD)/p,p'-DDT is not a reliable criterion for the identification of new DDT sources. → The more hydrophobic compounds have relatively higher sequestration fractions in soils with SOC contents >2%. → DDD may have higher sorption by soil organic matter than DDE. - The effect of soil organic matter on the sequestration of organochlorine pesticides (HCHs and DDTs) in soils was investigated in an innovative microcosm chamber.

  15. Dissolved organic nitrogen (DON) losses from nested artificially drained lowland catchments with contrasting soil types

    Science.gov (United States)

    Tiemeyer, Bärbel; Kahle, Petra; Lennartz, Bernd

    2010-05-01

    Artificial drainage is a common practice to improve moisture and aeration conditions of agricultural land. It shortens the residence time of water in the soil and may therefore contribute to the degradation of peatlands as well as to the still elevated level of diffuse pollution of surface water bodies, particularly if flow anomalies like preferential flow cause a further acceleration of water and solute fluxes. Especially in the case of nitrate, artificially drained sub-catchments are found to control the catchment-scale nitrate losses. However, it is frequently found that nitrate losses and nitrogen field balances do not match. At the same time, organic fertilizers are commonly applied and, especially in lowland catchments, organic soils have been drained for agricultural use. Thus, the question arises whether dissolved organic nitrogen (DON) forms an important component of the nitrogen losses from artificially drained catchments. However, in contrast to nitrate and even to dissolved organic carbon (DOC), this component is frequently overlooked, especially in nested catchment studies with different soil types and variable land use. Here, we will present data from a hierarchical water quantity and quality measurement programme in the federal state Mecklenburg-Vorpommern (North-Eastern Germany). The monitoring programme in the pleistocene lowland catchment comprises automatic sampling stations at a collector drain outlet (4.2 ha catchment), at a ditch draining arable land on mineral soils (179 ha), at a ditch mainly draining grassland on organic soils (85 ha) and at a brook with a small rural catchment (15.5 km²) of mixed land use and soil types. At all sampling stations, daily to weekly composite samples were taken, while the discharge and the meteorological data were recorded continuously. Water samples were analyzed for nitrate-nitrogen, ammonium-nitrogen and total nitrogen. We will compare two years: 2006/07 was a very wet year (P = 934 mm) with a high summer

  16. Modification of the RothC model to simulate soil C mineralization of exogenous organic matter

    Science.gov (United States)

    Mondini, Claudio; Cayuela, Maria Luz; Sinicco, Tania; Fornasier, Flavio; Galvez, Antonia; Sánchez-Monedero, Miguel Angel

    2017-07-01

    The development of soil organic C (SOC) models capable of producing accurate predictions for the long-term decomposition of exogenous organic matter (EOM) in soils is important for the effective management of organic amendments. However, reliable C modeling in amended soils requires specific optimization of current C models to take into account the high variability in EOM origin and properties. The aim of this work was to improve the prediction of C mineralization rates in amended soils by modifying the RothC model to encompass a better description of EOM quality. The standard RothC model, involving C input to the soil only as decomposable (DPM) or resistant (RPM) organic material, was modified by introducing additional pools of decomposable (DEOM), resistant (REOM) and humified (HEOM) EOM. The partitioning factors and decomposition rates of the additional EOM pools were estimated by model fitting to the respiratory curves of amended soils. For this task, 30 EOMs from 8 contrasting groups (compost, anaerobic digestates, sewage sludge, agro-industrial waste, crop residues, bioenergy by-products, animal residues and meat and bone meals) were added to 10 soils and incubated under different conditions. The modified RothC model was fitted to C mineralization curves in amended soils with great accuracy (mean correlation coefficient 0.995). In contrast to the standard model, the EOM-optimized RothC was able to better accommodate the large variability in EOM source and composition, as indicated by the decrease in the root mean square error of the simulations for different EOMs (from 29.9 to 3.7 % and 20.0 to 2.5 % for soils amended with bioethanol residue and household waste compost, respectively). The average decomposition rates for DEOM and REOM pools were 89 and 0.4 yr-1, higher than the standard model coefficients for DPM (10 yr-1) and RPM (0.3 yr-1). The results indicate that the explicit treatment of EOM heterogeneity enhances the model ability to describe amendment

  17. CHANGES IN SOIL CHEMICAL PROPERTIES OF ORGANIC PADDY FIELD WITH AZOLLA APPLICATION

    Directory of Open Access Journals (Sweden)

    Jauhari Syamsiyah

    2016-12-01

    Full Text Available The use of organic fertilizer is a way to improve soil fertility. Azolla can be used as organic fertilizer. This study aims to determine the effect of Azolla (Azolla mycrophylla. L on some soil chemical properties on organic paddy field. The field experiments used factorial complete randomized block design of three factors, namely Azolla (0 and 2 tons/ha, Manure (0 and 10 tons/ha and Rice Varieties (Mira1, Mentik Wangi and Merah Putih, with three times replication. Using Azolla on an organic paddy field does not significantly increase the levels of soil N, organic C, Cation Exchange Capacity and soil pH. However Azolla’s influence on soil available P is significant.

  18. Formation and Stability of Microbially Derived Soil Organic Matter

    Science.gov (United States)

    Waldrop, M. P.; Creamer, C.; Foster, A. L.; Lawrence, C. R.; Mcfarland, J. W.; Schulz, M. S.

    2017-12-01

    Soil carbon is vital to soil health, food security, and climate change mitigation, but the underlying mechanisms controlling the stabilization and destabilization of soil carbon are still poorly understood. There has been a conceptual paradigm shift in how soil organic matter is formed which now emphasizes the importance of microbial activity to build stable (i.e. long-lived) and mineral-associated soil organic matter. In this conceptual model, the consumption of plant carbon by microorganisms, followed by subsequent turnover of microbial bodies closely associated with mineral particles, produces a layering of amino acid and lipid residues on the surfaces of soil minerals that remains protected from destabilization by mineral-association and aggregation processes. We tested this new model by examining how isotopically labeled plant and microbial C differ in their fundamental stabilization and destabilization processes on soil minerals through a soil profile. We used a combination of laboratory and field-based approaches to bridge multiple spatial scales, and used soil depth as well as synthetic minerals to create gradients of soil mineralogy. We used Raman microscopy as a tool to probe organic matter association with mineral surfaces, as it allows for the simultaneous quantification and identification of living microbes, carbon, minerals, and isotopes through time. As expected, we found that the type of minerals present had a strong influence on the amount of C retained, but the stabilization of new C critically depends on growth, death, and turnover of microbial cells. Additionally, the destabilization of microbial residue C on mineral surfaces was little affected by flushes of DOC relative to wet-dry cycles alone. We believe this new insight into microbial mechanisms of C stabilization in soils will eventually lead to new avenues for measuring and modeling SOM dynamics in soils, and aid in the management of soil C to mediate global challenges.

  19. Soil organic matter in fire-affected pastures and in an Araucaria forest in South-Brazilian Leptosols

    Directory of Open Access Journals (Sweden)

    Mariana da Luz Potes

    2012-05-01

    Full Text Available The objective of this work was to evaluate the distribution pattern and composition of soil organic matter (SOM and its physical pools of Leptosols periodically affected by fire over the last 100 years in South Brazil. Soil samples at 0-5, 5-10, and 10-15 cm depths were collected from the following environments: native pasture without burning in the last year and grazed with 0.5 livestock per hectare per year (1NB; native pasture without burning in the last 23 years and grazed with 2.0 livestock per hectare per year (23NB; and an Araucaria forest (AF. Physical fractionation was performed with the 0-5 and 5-10 cm soil layers. Soil C and N stocks were determined in the three depths and in the physical pools, and organic matter was characterized by infrared spectroscopy and thermogravimetry. The largest C stocks in all depths and physical pools were found under the AF. The 23NB environment showed the lowest soil C and N stocks at the 5-15 cm depth, which was related to the end of burning and to the higher grazing intensity. The SOM of the occluded light fraction showed a greater chemical recalcitrance in 1NB than in 23NB. Annual pasture burning does not affect soil C stocks up to 15 cm of depth.

  20. ES1406 COST Action: Soil fauna: Key to Soil Organic Matter Dynamicsand Fertility. How far have we got?

    DEFF Research Database (Denmark)

    Jiménez, Juan; Filser, Juliane; Barot, Sébastien

    Soil organic matter (SOM) is key to soil fertility, climate change mitigation, combatting land degradation, and the conservation of above- and below-ground biodiversity and associated ecosystem services like decomposition, nutrient cycling, carbon sequestration, detoxification and maintenance...... of soil physico-chemical properties. SOM dynamics represent the balance between the input of plant material (residues, root-derived materials) and the output through decomposition (OM mineralization) by organisms, erosion and leaching. Approximately 20% of global CO2 emissions, one third of global CH4...... emissions and two thirds of N2O emissions originate from soils. In many soils, most of the macro-aggregate structure is formed by the activities of soil invertebrates and roots, with important consequences for soil organic matter dynamics, carbon sequestration and water infiltration at several spatial...

  1. Effects of biochar blends on microbial community composition in two coastal plain soils

    Science.gov (United States)

    The amendment of soil with biochar has been demonstrated to have an effect not only on the soil physicochemical properties, but also on soil microbial community composition and activity. Previous reports have demonstrated significant impacts on soil microbial community structure....

  2. [Species composition and diversity of soil mesofauna in the 'Holy Hills' fragmentary tropical rain forest of Xishuangbanna, China].

    Science.gov (United States)

    Yang, X; Sha, L

    2001-04-01

    The species composition and diversity of soil mesofauna were examined in fragmented dry tropical seasonal rainforest of tow 'Holy Hills' of Dai nationality, compared with the continuous moist tropical seasonal rain forest of Nature Reserve in Xishuangbanna area. 5 sample quadrats were selected along the diagonal of 20 m x 20 m sampling plot, and the samples of litterfall and 0-3 cm soil were collected from each 50 cm x 10 cm sample quadrat. Animals in soil sample were collected by using dry-funnel(Tullgren's), were identified to their groups according to the order. The H' index, D.G index and the pattern of relative abundance of species were used to compare the diversity of soil mesofauna. The results showed that the disturbance of vegetation and soil resulted by tropical rainforest fragmentation was the major factor affecting the diversity of soil mesofauna. Because the fragmented forest was intruded by some pioneer tree species and the "dry and warm" effect operated, this forest had more litterfall on the floor and more humus in the soil than the continuous moist rain forest. The soil condition with more soil organic matter, total N and P, higher pH value and lower soil bulk density became more favorable to the soil mesofauna. Therefore, the species richness, abundance and diversity of soil mesofauna in fragmented forests were higher than those in continuous forest, but the similarity of species composition in fragmented forest to the continuous forest was minimal. Soil mesofauna diversity in fragmented forests did not change with decreasing fragmented area, indicating that there was no species-area effect operation in this forest. The pattern of relative abundance of species in these forest soils was logarithmic series distribution.

  3. Managing soil nutrients with compost in organic farms of East Georgia

    Science.gov (United States)

    Ghambashidze, Giorgi

    2013-04-01

    Soil Fertility management in organic farming relies on a long-term integrated approach rather than the more short-term very targeted solutions common in conventional agriculture. Increasing soil organic matter content through the addition of organic amendments has proven to be a valuable practice for maintaining or restoring soil quality. Organic agriculture relies greatly on building soil organic matter with compost typically replacing inorganic fertilizers and animal manure as the fertility source of choice. In Georgia, more and more attention is paid to the development of organic farming, occupying less than 1% of total agricultural land of the country. Due to increased interest towards organic production the question about soil amendments is arising with special focus on organic fertilizers as basic nutrient supply sources under organic management practice. In the frame of current research two different types of compost was prepared and their nutritional value was studied. The one was prepared from organic fraction municipal solid waste and another one using fruit processing residues. In addition to main nutritional properties both composts were tested on heavy metals content, as one of the main quality parameter. The results have shown that concentration of main nutrient is higher in municipal solid waste compost, but it contains also more heavy metals, which is not allowed in organic farming system. Fruit processing residue compost also has lower pH value and is lower in total salt content being is more acceptable for soil in lowlands of East Georgia, mainly characterised by alkaline reaction. .

  4. Increased microbial functional diversity under long-term organic and integrated fertilization in a paddy soil.

    Science.gov (United States)

    Ding, Long-Jun; Su, Jian-Qiang; Sun, Guo-Xin; Wu, Jin-Shui; Wei, Wen-Xue

    2018-02-01

    Microbes play key roles in diverse biogeochemical processes including nutrient cycling. However, responses of soil microbial community and functional genes to long-term integrated fertilization (chemical combined with organic fertilization) remain unclear. Here, we used pyrosequencing and a microarray-based GeoChip to explore the shifts of microbial community and functional genes in a paddy soil which received over 21-year fertilization with various regimes, including control (no fertilizer), rice straw (R), rice straw plus chemical fertilizer nitrogen (NR), N and phosphorus (NPR), NP and potassium (NPKR), and reduced rice straw plus reduced NPK (L-NPKR). Significant shifts of the overall soil bacterial composition only occurred in the NPKR and L-NPKR treatments, with enrichment of certain groups including Bradyrhizobiaceae and Rhodospirillaceae families that benefit higher productivity. All fertilization treatments significantly altered the soil microbial functional structure with increased diversity and abundances of genes for carbon and nitrogen cycling, in which NPKR and L-NPKR exhibited the strongest effect, while R exhibited the least. Functional gene structure and abundance were significantly correlated with corresponding soil enzymatic activities and rice yield, respectively, suggesting that the structural shift of the microbial functional community under fertilization might promote soil nutrient turnover and thereby affect yield. Overall, this study indicates that the combined application of rice straw and balanced chemical fertilizers was more pronounced in shifting the bacterial composition and improving the functional diversity toward higher productivity, providing a microbial point of view on applying a cost-effective integrated fertilization regime with rice straw plus reduced chemical fertilizers for sustainable nutrient management.

  5. Spatio-temporal variability of the molecular fingerprint of soil dissolved organic matter in a headwater agricultural catchment

    Science.gov (United States)

    Jeanneau, Laurent; Pierson-Wickmann, Anne-Catherine; Jaffrezic, Anne; Lambert, Thibault; Gruau, Gérard

    2013-04-01

    Dissolved organic matter (DOM) is implied in (i) ecosystem services such as the support of biodiversity, (ii) the alteration of the drinkable water quality by formation of trihalomethane and (iii) the transfer of micropollutants from soils to rivers. Moreover, since DOM connects soils and oceans that are interacting with the atmosphere, understanding its biogeochemistry will help in investigating the carbon cycle and in creating strategies to mitigate climate change. DOM in headwater stream ecosystems is mainly inherited from allochtonous inputs with different reservoirs being mobilized during storm and interstorm events at the scale of an hydrological year. Those changes in DOM reservoirs, if accompanied by composition and reactivity changes, may impact DOM ecosystem services and drinking water production processes. Elucidating the compositional changes due to changes in the source of DOM in rivers has thus become a important axis of DOM research. The aim of this study is to test the ability of the molecular tools of the organic geochemistry and more specifically the combination of thermochemiolysis and gas chromatography - mass spectrometry (THM-GC-MS) to (i) link the variability of the river DOM composition to different DOM reservoirs in catchment soils and (ii) provide hypothesis on the nature and the mechanisms of formation (microbial growth, litter decomposition) of those reservoirs. This analytical method seems particularly adapted since it allows the differentiation between vegetal and microbial inputs and the determination of the extent of the biodegradation process of biomolecules such as lignin. To test this method, the molecular fingerprint of soil DOM has been investigated in the wetland area of a small (500 ha) agricultural catchment (the so-called Kervidy-Naizin catchment) located in Brittany, western France. The soil DOM was sampled fortnightly at three depths using zero-tension lysimeters during the hydrological year 2010-2011. The samples were

  6. Persistent organic pollutants in the Tibetan surface soil: Spatial distribution, air–soil exchange and implications for global cycling

    International Nuclear Information System (INIS)

    Wang Xiaoping; Sheng Jiujiang; Gong Ping; Xue Yonggang; Yao Tandong; Jones, Kevin C.

    2012-01-01

    There are limited data on persistent organic pollutants (POPs) in the soils of the Tibetan Plateau. This paper presents data from a survey of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in 40 background surface (0–5 cm) soils of the Tibetan Plateau. Soil concentrations (pg/g, dw) ranged as follows: DDTs, 13-7700; HCHs, 64-847; HCB, 24-564; sum of 15 PCBs, 75-1021; and sum of 9 PBDEs, below detection limit −27. Soil DDT, HCB, PCB and PBDE concentrations were strongly influenced by soil organic carbon content. HCH concentrations were clearly associated with the proximity to source regions in south Asia. The air–soil equilibrium status of POPs suggested the Tibetan soils may be partial “secondary sources” of HCB, low molecular weight PCBs and HCHs and will likely continue to be “sinks” for the less volatile DDE and DDT. - Highlights: ► Soil organic carbon content influence the spatial distribution of persistent organic pollutants. ► The Tibetan soil acts as “secondary sources” for HCB, low molecular weight PCBs and HCHs. ► The Tibetan soil will continue to be “sinks” for DDE and DDT. - Tibetan soils may be potential “secondary sources” of the HCB, low molecular weight PCBs and HCHs that are observed in air.

  7. Application of wastewater with high organic load for saline-sodic soil reclamation focusing on soil purification ability

    Directory of Open Access Journals (Sweden)

    M.A. Kameli

    2017-04-01

    Full Text Available Fresh water source scarcity in arid and semiarid area is limitation factor for saline-sodic soil reclamation. The reusing of agricultural drainage and industrial wastewater are preferred strategies for combating with this concern. The objective of current study was evaluation in application of industrial sugar manufacture wastewater due to high soluble organic compounds in saline-sodic and sodic soil. Also soil ability in wastewater organic compounds removal was second aim of present study. Saline-sodic and sodic soil sample was leached in soil column by diluted wastewater of amirkabir sugar manufacture in Khuzestan Province of Iran at constant water head. Sodium, electric conductivity and chemical oxygen demand of soil column leachate were measured per each pore volume. The experimental kinetics of wastewater organic compounds on two saline-sodic and sodic soil were also investigated by three pseudo second order, intra particle diffusion and elovich model. The results of current study showed that electric conductivity of saline-sodic soil was decreased to 90% during 3 initial pore volumes, from other side exchangeable sodium percent of saline-sodic and sodic soil decreased 30 and 71 percent, respectively. There were no significant different between wastewater chemical oxygen demand removal by saline-sodic and sodic soil in both batch and column studies. Wastewater chemical oxygen demand was decreased to 35% during pass through soil column. The results showed that the adsorption kinetics of wastewater organic compounds were best fitted by the pseudo-second order model with 99 percent correlation coefficient (r2=0.99%.

  8. Plant species and functional group effects on abiotic and microbial soil properties and plant-soil feedback responses in two grasslands

    NARCIS (Netherlands)

    Bezemer, T.M.; Lawson, C.S.; Hedlund, K.; Edwards, A.R.; Brooks, A.J.; Igual, J.M.; Mortimer, S.R.; Putten, van der W.H.

    2006-01-01

    1 Plant species differ in their capacity to influence soil organic matter, soil nutrient availability and the composition of soil microbial communities. Their influences on soil properties result in net positive or negative feedback effects, which influence plant performance and plant community

  9. Sorption, degradation and leaching of pesticides in soils amended with organic matter: A review

    Directory of Open Access Journals (Sweden)

    Fardin Sadegh-Zadeh

    2017-04-01

    Full Text Available The use of pesticides in modern agriculture is unavoidable because they are required to control weeds. Pesticides are poisonous; hence, they are dangerous if misused. Understanding the fate of pesticides will be useful to use them safely. Therefore, contaminations of water and soil resources could be avoided. The fates of pesticides in soils are influenced by their sorption, decomposition and movement. Degradation and leaching of pesticides are control by sorption. Soil organic matter and clay content are main soil constituents that have a high capacity for sorption of pesticides. Addition of organic maters to amend the soils is a usual practice that every year has been done in a huge area of worldwide.  The added organic amendments to the soils affect the fate of pesticides in soils as well. Pesticides fates in different soils are different. The addition of organic matter to soils causes different fates for pesticides as well. It is known from the studies that sorption of non-ionic pesticides by soil in aqueous system is controlled mainly by the organic matter content of the soils. Sorption of pesticides has been reported to increase by amending soils with organic matter. In general, conditions that promote microbial activity enhance the rate of pesticides degradation, and those that inhibit the growth of microorganisms reduce the rate of degradation. Amendment of soils with organic matter may modify leaching of pesticides in soil. Some studies showed that organic matter added to soils reduced pesticides in ground water. Generally, organic amendments induces the restriction of pesticides leaching in soils.

  10. Does Miscanthus cultivation on organic soils compensate for carbon loss from peat oxidation? A dual label study

    Science.gov (United States)

    Bader, Cédric; Leifeld, Jens; Müller, Moritz; Schulin, Rainer

    2016-04-01

    Agricultural use of organic soils requires drainage and thereby changes conditions in these soils from anoxic to oxic. As a consequence, organic carbon that had been accumulated over millennia is rapidly mineralized, so that these soils are converted from a CO2 sink to a source. The peat mineralization rate depends mainly on drainage depth, but also on crop type. Various studies show that Miscanthus, a C4 bioenergy plant, shows potential for carbon sequestration in mineral soils because of its high productivity, its dense root system, absence of tillage and high preharvest litterfall. If Miscanthus cropping would have a similar effect in organic soils, peat consumption and thus CO2 emissions might be reduced. For our study we compared two adjacent fields, on which organic soil is cultivated with Miscanthus (since 20 years) and perennial grass (since 6 years). Both sites are located in the Bernese Seeland, the largest former peatland area of Switzerland. To determine wether Miscanthus-derived carbon accumulated in the organic soil, we compared the stable carbon isotopic signatures of the experimental soil with those of an organic soil without any C4-plant cultivation history. To analyze the effect of C4-C accumulation on peat degradability we compared the CO2 emissions by incubating 90 soil samples of the two fields for more than one year. Additionally, we analysed the isotopic CO2 composition (13C, 14C) during the first 25 days of incubation after trapping the emitted CO2 in NaOH and precipitating it as BaCO3. The ∂13C values of the soil imply, that the highest share of C4-C of around 30% is situated at a depth of 10-20 cm. Corn that used to be cultivated on the grassland field before 2009 still accounts for 8% of SOC. O/C and H/C ratios of the peat samples indicate a stronger microbial imprint of organic matter under Miscanthus cultivation. The amount of CO2 emitted was not affected by the cultivation type. On average 57% of the CO2 was C4 derived in the

  11. Spatial patterns of soil organic carbon stocks in Estonian arable soils

    Science.gov (United States)

    Suuster, Elsa; Astover, Alar; Kõlli, Raimo; Roostalu, Hugo; Reintam, Endla; Penu, Priit

    2010-05-01

    Soil organic carbon (SOC) determines ecosystem functions, influencing soil fertility, soil physical, chemical and biological properties and crop productivity. Therefore the spatial pattern of SOC stocks and its appropriate management is important at various scales. Due to climate change and the contribution of carbon store in the soils, the national estimates of soil carbon stocks should be determined. Estonian soils have been well studied and mapped at a scale 1:10,000. Previous studies have estimated SOC stocks based on combinations of large groups of Estonian soils and the mean values of the soil profile database, but were not embedded into the geo-referenced databases. These studies have estimated SOC stocks of Estonian arable soils 122.3 Tg. Despite of available soil maps and databases, this information is still very poorly used for spatial soil modelling. The aim of current study is to assess and model spatial pattern of SOC stocks of arable soils on a pilot area Tartu County (area 3089 sq km). Estonian digital soil map and soil monitoring databases are providing a good opportunity to assess SOC stocks at various scales. The qualitative nature of the initial data from a soil map prohibits any straightforward use in modelling. Thus we have used several databases to construct models and linkages between soil properties that can be integrated into soil map. First step was to reorganize the soil map database (44,046 mapping units) so it can be used as an input to modelling. Arable areas were distinguished by a field layer of Agricultural Registers and Information Board, which provides precise information of current land use as it is the basis of paying CAP subsidies. The estimates of SOC content were found by using the arable land evaluation database of Tartu from the Estonian Land Board (comprising 950 sq km and 31,226 fields), where each soil type was assessed separately and average SOC content grouped by texture was derived. SOC content of epipedon varies in

  12. Tillage-induced changes to soil structure and organic carbon fractions in New Zealand soils

    International Nuclear Information System (INIS)

    Shepherd, T. G.; Saggar, S.; Ross, C. W.; Dando, J. L.; Newman, R. H.

    2001-01-01

    The effects of increasing cropping and soil compaction on aggregate stability and dry-sieved aggregate-size distribution, and their relationship to total organic C (TOC) and the major functional groups of soil organic carbon, were investigated on 5 soils of contrasting mineralogy. All soils except the allophanic soil showed a significant decline in aggregate stability under medium- to long-term cropping. Mica-rich, fine-textured mineral and humic soils showed the greatest increase in the mean weight diameter (MWD) of dry aggregates, while the oxide-rich soils, and particularly the allophanic soils, showed only a slight increase in the MWD after long-term cropping. On conversion back to pasture, the aggregate stability of the mica-rich soils increased and the MWD of the aggregate-size distribution decreased, with the humic soil showing the greatest recovery. Aggregate stability and dry aggregate-size distribution patterns show that soil resistance to structural degradation and soil resilience increased from fine-textured to coarse-textured to humic mica-rich soils to oxide-rich soils to allophanic soils. Coarse- and fine-textured mica-rich and oxide-rich soils under pasture contained medium amounts of TOC, hot-water soluble carbohydrate (WSC), and acid hydrolysable carbohydrate (AHC), all of which declined significantly under cropping. The rate of decline varied with soil type in the initial years of cropping, but was similar under medium- and long-term cropping. TOC was high in the humic mica-rich and allophanic soils, and levels did not decline appreciably under medium- and long-term cropping. 13 C-nuclear magnetic resonance evidence also indicates that all major functional groups of soil organic carbon declined under cropping, with O-alkyl C and alkyl C showing the fastest and slowest rate of decline, respectively. On conversion back to pasture, both WSC and AHC returned to levels originally present under long-term pasture. TOC recovered to original pasture

  13. Cs adsorption on the clay-sized fraction of various soils: effect of organic matter destruction and charge compensating cation

    International Nuclear Information System (INIS)

    Staunton, S.; Levacic, P.

    1999-01-01

    The association of organic matter with clay minerals may decrease their affinity for Cs and thus enhance its bioavailability. We have investigated this hypothesis by comparing Cs adsorption on several soils, both topsoils and the corresponding subsoils, before and after organic matter destruction with H 2 O 2 . The clay-sized fractions were homoionic in either K, Na or Ca, to avoid artefacts due to variable composition of the exchange complex. All experiments were carried out in dilute suspension under controlled conditions. The affinity of the clay-sized fractions for Cs and the value of the Freundlich b parameter are typical of illites. This supports the hypothesis that the adsorption properties of soils are dominated by small amounts of illite. However, if this is the case, the affinity of soil illites is higher than that of reference illites. The destruction of organic matter has a variable effect. In some cases, a marked enhancement is observed, in others there is no significant effect, or a small decrease. There is no clear pattern relating the effect of organic matter destruction and either dominant clay mineralogy or organic matter content. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  14. Soil enzymology in the recycling of organic wastes and environmental restoration

    Energy Technology Data Exchange (ETDEWEB)

    Trasar-Cepeda, Carmen [IIAG-CSIC, Santiago de Compostela (Spain). Dept. de Bioquimica del Suelo; Rad, Carlos [Burgos Univ. (Spain). Soil Science and Agricultural Chemistry, Faculty of Science; Hernandez, Teresa; Garcia, Carlos (eds.) [CEBAS-CSIC, Murcia (Spain). Dept. of Soil and Water Conservation; Gonzalez-Carcedo, Salvador [Burgos Univ. (Spain). Soil Science and Agricultural Chemistry, Polytechnic High School

    2012-07-01

    Soil enzymes play a fundamental role in many soil processes such as the mineralization of organic matter, the synthesis of humic substances, the degradation of xenobiotics or the mechanisms involved in the biocontrol of plant pathogens. Their direct link with soil microorganisms gives them a key role as biomonitors of the evolution of soil quality or in the monitoring of the application of organic amendments to degraded soils. As a consequence of the importance of soil enzymes on soil processes, there is an increasing interest in their study, as well as in the application of molecular techniques as diagnostic tools. (orig.)

  15. Radionuclide - Soil Organic Matter Interactions

    DEFF Research Database (Denmark)

    Carlsen, Lars

    1985-01-01

    Interactions between soil organic matter, i.e. humic and fulvic acids, and radionuclides of primary interest to shallow land burial of low activity solid waste have been reviewed and to some extent studied experimentally. The radionuclides considered in the present study comprise cesium, strontium...

  16. Response of soil dissolved organic matter to microplastic addition in Chinese loess soil

    NARCIS (Netherlands)

    Liu, Hongfei; Yang, Xiaomei; Liu, Guobin; Liang, Chutao; Xue, Sha; Chen, Hao; Ritsema, Coen J.; Geissen, Violette

    2017-01-01

    Plastic debris is accumulating in agricultural land due to the increased use of plastic mulches, which is causing serious environmental problems, especially for biochemical and physical properties of the soil. Dissolved organic matter (DOM) plays a central role in driving soil biogeochemistry, but

  17. Total organic carbon in aggregates as a soil recovery indicator

    Science.gov (United States)

    Luciene Maltoni, Katia; Rodrigues Cassiolato, Ana Maria; Amorim Faria, Glaucia; Dubbin, William

    2015-04-01

    The soil aggregation promotes physical protection of organic matter, preservation of which is crucial to improve soil structure, fertility and ensure the agro-ecosystems sustainability. The no-tillage cultivation system has been considered as one of the strategies to increase total soil organic carbono (TOC) contents and soil aggregation, both are closely related and influenced by soil management systems. The aim of this study was to evaluate the distribution of soil aggregates and the total organic carbon inside aggregates, with regard to soil recovery, under 3 different soil management systems, i.e. 10 and 20 years of no-tillage cultivation as compared with soil under natural vegetation (Cerrado). Undisturbed soils (0-5; 5-10; and 10-20 cm depth) were collected from Brazil, Central Region. The soils, Oxisols from Cerrado, were collected from a field under Natural Vegetation-Cerrado (NV), and from fields that were under conventional tillage since 1970s, and 10 and 20 years ago were changed to no-tillage cultivation system (NT-10; NT-20 respectively). The undisturbed samples were sieved (4mm) and the aggregates retained were further fractionated by wet sieving through five sieves (2000, 1000, 500, 250, and 50 μm) with the aggregates distribution expressed as percentage retained by each sieve. The TOC was determined, for each aggregate size, by combustion (Thermo-Finnigan). A predominance of aggregates >2000 μm was observed under NV treatment (92, 91, 82 %), NT-10 (64, 73, 61 %), and NT-20 (71, 79, 63 %) for all three depths (0-5; 5-10; 10-20 cm). In addition greater quantities of aggregates in sizes 1000, 500, 250 and 50 μm under NT-10 and NT-20 treatments, explain the lower aggregate stability under these treatments compared to the soil under NV. The organic C concentration for NV in aggregates >2000 μm was 24,4; 14,2; 8,7 mg/g for each depth (0-5; 5-10; 10-20 cm, respectively), higher than in aggregates sized 250-50 μm (7,2; 5,5; 4,4 mg/g) for all depths

  18. Effect of N and P addition on soil organic C potential mineralization in forest soils in South China

    Institute of Scientific and Technical Information of China (English)

    OUYANG Xuejun; ZHOU Guoyi; HUANG Zhongliang; ZHOU Cunyu; LI Jiong; SHI Junhui; ZHANG Deqiang

    2008-01-01

    Atmospheric nitrogen deposition is at a high level in some forests of South China. The effects of addition of exogenous N and P on soil organic carbon mineralization were studied to address: (1) if the atmospheric N deposition promotes soil C storage through decreasing mineralization; (2) if the soil available P is a limitation to organic carbon mineralization. Soils (0-10 cm) was sampled from monsoon evergreen broad-leaved forest (MEBF), coniferous and broad-leaved mixed forest (CBMF), and Pinus massoniana forest (PMF) in Dinghushan Biosphere Reserve (located in Gnangdong Province, China). The soils were incubated at 25℃ for 45 weeks, with addition of N (NH4NO3 solution) or P (KH2PO4 solution). CO2-C emission and the inorganic N (NH4+-N and NO3--N) of the soils were determined during the incubation. The results showed that CO2-C emission decreased with the N addition. The addition of P led to a short-term sharp increase in CO2 emission after P application, and the responses of CO2-C evolution to P addition in the later period of incubation related to forest types. Strong P inhibition to CO2 emission occurred in both PMF and CBMF soils in the later incubation. The two-pool kinetic model was fitted well to the data for C turnover in this experiment. The model analysis demonstrated that the addition of N and P changed the distribution of soil organic C between the labile and recalcitrant pool, as well as their mineralization rates. In our experiment, soil pH can not completely explain the negative effect of N addition on CO2-C emission. The changes of soil inorganic N during incubation seemed to support the hypothesis that the polymerization of added nitrogen with soil organic compound by abiotic reactions during incubation made the added nitrogen retard the soil organic carbon mineralization. We conclude that atmospheric N deposition contributes to soil C accretion in the three subtropical forest ecosystems, however, the shortage of soil available P in CBMF and

  19. Out of sight - Profiling soil characteristics, nutrients and microbial communities affected by organic amendments down to one meter in a long-term maize cultivation experiment

    Science.gov (United States)

    Lehtinen, Taru; Mikkonen, Anu; Zavattaro, Laura; Grignani, Carlo; Baumgarten, Andreas; Spiegel, Heide

    2016-04-01

    Soil characteristics, nutrients and microbial activity in the deeper soil layers are topics not of-ten covered in agricultural studies since the main interest lies within the most active topsoils and deep soils are more time-consuming to sample. Studies have shown that deep soil does matter, although biogeochemical cycles are not fully understood yet. The main aim of this study is to investigate the soil organic matter dynamics, nutrients and microbial community composition in the first meter of the soil profiles in the long-term maize cropping system ex-periment Tetto Frati, in the vicinity of the Po River in Northern Italy. The trial site lies on a deep, calcareous, free-draining soil with a loamy texture. The following treatments have been applied since 1992: 1) maize for silage with 250 kg mineral N ha-1 (crop residue removal, CRR), 2) maize for grain with 250 kg mineral N ha-1 (crop residue incorporation, CRI), 3) maize for silage with 250 kg bovine slurry N ha-1 (SLU), 4) maize for silage with 250 kg farm yard manure N ha-1 (FYM). Soil characteristics (pH, carbonate content, soil organic carbon (SOC), aggregate stability (WSA)), and nutrients (total nitrogen (Nt), CAL-extractable phos-phorous (P) and potassium (K), potential N mineralisation) were investigated. Bacteri-al community composition was investigated with Ion PGM high-throughput sequencing at the depth of 8000 sequences per sample. Soil pH was moderately alkaline in all soil samples, in-creasing with increasing soil depth, as the carbonate content increased. SOC was significantly higher in the treatments with organic amendments (CRI, SLU and FYM) compared to CRR in 0-25 cm (11.1, 11.6, 14.7 vs. 9.8 g kg-1, respectively), but not in the deeper soil. At 50-75 cm soil depth FYM treatment revealed higher WSA compared to CRR, as well as higher CAL-extractable K (25 and 15 mg kg-1, respectively) and potential N mineralisation (11.30 and 8.78 mg N kg-1 7d-1, respectively). At 75-100 cm soil depth, SLU and

  20. Defining the Glass Composition Limits for SRS Contaminated Soils

    International Nuclear Information System (INIS)

    Cicero, C.A.; Bickford, D.F.; Crews, W.O.

    1995-01-01

    Contaminated soil resulting from the excavation, repair, and decommissioning of facilities located at the Savannah River Site (SRS) is currently being disposed of by shallow land burial or is being stored when considered only hazardous. Vitrification of this waste is being investigated, since it will bind the hazardous and radioactive species in a stable and durable glass matrix, which will reduce the risk of ground water contamination. However, the composition limits for producing durable glass have to be determined before the technology can be applied. Glass compositions, consisting of SRS soil and glass forming additives, were tested on a crucible-scale in three ternary phase systems. Nine different glass compositions were produced, with waste loadings ranging from 43 to 58 weight percent. These were characterized using varoius chemical methods and tested for durability in both alkaline and acidic environments. All nine performed well in alkaline environments, but only three met the strictest criteria for the acidic environment tests. Although the glasses did not meet all of the limits for the acidic tests, the test was performed on very conservative size samples, so the results were also conservative. Therefore, enough evidence was found to provide proof that SRS soil can be vitrified in a durable glass matrix

  1. A laboratory examination of organic matter degradation in a B horizon soil from post-mining reconstructed prime farmland soil

    International Nuclear Information System (INIS)

    Felton, G.K.; Taraba, J.L.

    1994-01-01

    A laboratory study was conducted to assess the effect of reclamation treatment on the aerobic degradation rate of organic matter composed of horse faeces, urine, and straw bedding. It was hypothesized that different physical treatments of soil removed during the mining process would alter the rate of organic matter decomposition. The soils were from the B horizon of reclaimed prime farmland. The B horizon was reconstructed using one of two treatments: soil direct hauled from the mining site to the reconstruction site; soil hauled from a 6-month-old stockpile. The soil that was immediately replaced exhibited organic matter degradation rates similar to a control whereas the stockpiled soil organic matter degradation rates were depressed. This implies that stockpiling adversely affects the microbial population. Prescription limiting, typically done during reclamation, did have the desired effect on pH and did not interfere with organic matter degradation. 15 refs., 1 fig., 4 tabs

  2. Carbon sequestration in soil by in situ catalyzed photo-oxidative polymerization of soil organic matter.

    Science.gov (United States)

    Piccolo, Alessandro; Spaccini, Riccardo; Nebbioso, Antonio; Mazzei, Pierluigi

    2011-08-01

    Here we describe an innovative mechanism for carbon sequestration in soil by in situ photopolymerization of soil organic matter under biomimetic catalysis. Three different Mediterranean soils were added with a synthetic water-soluble iron-porphyrin, irradiated by solar light, and subjected first to 5 days incubation and, then, 15, and 30 wetting and drying (w/d) cycles. The in situ catalyst-assisted photopolymerization of soil organic carbon (SOC) increased water stability of soil aggregates both after 5 days incubation and 15 w/d cycles, but not after 30 w/d cycles. Particle-size distribution of all treated soils confirmed the induced soil physical improvement, by showing a concomitant lower yield of the clay-sized fraction and larger yields of either coarse sand- or fine sand-size fractions, depending on soil texture, though only after 5 days incubation. The gain in soil physical quality was reflected by the shift of OC content from small to large soil aggregates, thereby suggesting that photopolymerization stabilized OC by both chemical and physical processes. A further evidence of the carbon sequestration capacity of the photocatalytic treatment was provided by the significant reduction of CO(2) respired by all soils after both incubation and w/d cycles. Our findings suggest that "green" catalytic technologies may potentially be the bases for future practices to increase soil carbon stabilization and mitigate CO(2) emissions from arable soils.

  3. Soil organic matter on citrus plantation in Eastern Spain

    Science.gov (United States)

    Cerdà, Artemi; Pereira, Paulo; Novara, Agata; Prosdocimi, Massimo

    2015-04-01

    Citrus plantations in Eastern Spain are the main crop and Valencia region is the largest world exporter. The traditional plantation are located on flood irrigated areas and the new plantation are located on slopes were drip irrigation is the source of the wetting. It has been demonstrate that the citrus plantations contribute to high erosion rates on slopes (Cerdà et al., 2009b) as it is usual on agriculture land (Cerdà et al., 2009a), but when organic farming is present the soil erosion is much lower (Cerdà and Jurgensen, 2008; Cerdà et al., 2009; Cerdà and Jurgensen, 2011). This is a worldwide phenomenon (Wu et al., 2007; Wu et al., 2011; Xu et al., 2010; Xu et al., 2012a; Xu et al., 2012b), which are a key factor of the high erosion rates in rural areas (García Orenes et al., 2009: García Orenes et al., 20010; García Orenes et al., 2012; Haregewyn et al., 2013; Zhao et al., 2013). The key factor of the contrasted response of soils to the rain in citrus is the organic matter cover. This is why the Soil Erosion and Degradation Research Team developed a survey to determine the soil erosion rates on citrus orchards under different managements. A hundred of samples were collected in a citrus plantation on slope under conventional management (Chemical management), one on organic farming, one on traditional flood irrigated organic farming and one on traditional chemical flooding farm. The organic farming soils were treated with 10000 Kg ha-1 of manure yearly. The results show that the mean soil organic matter content was 1.24 %, 3.54%, 5,43% and 2.1% respectively, which show a clear impact of organic farming in the recovery of the soil organic matter. meanwhile the on the slopes and the flood-irrigated soils are Acknowledgements The research projects GL2008-02879/BTE, LEDDRA 243857 and PREVENTING AND REMEDIATING DEGRADATION OF SOILS IN EUROPE THROUGH LAND CARE (RECARE)FP7- ENV-2013- supported this research. References Cerdà, A., Flanagan, D.C., le Bissonnais

  4. Soil microbial biomass, activity and community composition along altitudinal gradients in the High Arctic (Billefjorden, Svalbard)

    Science.gov (United States)

    Kotas, Petr; Šantrůčková, Hana; Elster, Josef; Kaštovská, Eva

    2018-03-01

    The unique and fragile High Arctic ecosystems are vulnerable to global climate warming. The elucidation of factors driving microbial distribution and activity in arctic soils is essential for a comprehensive understanding of ecosystem functioning and its response to environmental change. The goals of this study were to investigate microbial biomass and activity, microbial community structure (MCS), and their environmental controls in soils along three elevational transects in the coastal mountains of Billefjorden, central Svalbard. Soils from four different altitudes (25, 275, 525 and 765 m above sea level) were analyzed for a suite of characteristics including temperature regimes, organic matter content, base cation availability, moisture, pH, potential respiration, and microbial biomass and community structure using phospholipid fatty acids (PLFAs). We observed significant spatial heterogeneity of edaphic properties among transects, resulting in transect-specific effects of altitude on most soil parameters. We did not observe any clear elevation pattern in microbial biomass, and microbial activity revealed contrasting elevational patterns between transects. We found relatively large horizontal variability in MCS (i.e., between sites of corresponding elevation in different transects), mainly due to differences in the composition of bacterial PLFAs, but also a systematic altitudinal shift in MCS related to different habitat preferences of fungi and bacteria, which resulted in high fungi-to-bacteria ratios at the most elevated sites. The biological soil crusts on these most elevated, unvegetated sites can host microbial assemblages of a size and activity comparable to those of the arctic tundra ecosystem. The key environmental factors determining horizontal and vertical changes in soil microbial properties were soil pH, organic carbon content, soil moisture and Mg2+ availability.

  5. Soil microbial biomass, activity and community composition along altitudinal gradients in the High Arctic (Billefjorden, Svalbard

    Directory of Open Access Journals (Sweden)

    P. Kotas

    2018-03-01

    Full Text Available The unique and fragile High Arctic ecosystems are vulnerable to global climate warming. The elucidation of factors driving microbial distribution and activity in arctic soils is essential for a comprehensive understanding of ecosystem functioning and its response to environmental change. The goals of this study were to investigate microbial biomass and activity, microbial community structure (MCS, and their environmental controls in soils along three elevational transects in the coastal mountains of Billefjorden, central Svalbard. Soils from four different altitudes (25, 275, 525 and 765 m above sea level were analyzed for a suite of characteristics including temperature regimes, organic matter content, base cation availability, moisture, pH, potential respiration, and microbial biomass and community structure using phospholipid fatty acids (PLFAs. We observed significant spatial heterogeneity of edaphic properties among transects, resulting in transect-specific effects of altitude on most soil parameters. We did not observe any clear elevation pattern in microbial biomass, and microbial activity revealed contrasting elevational patterns between transects. We found relatively large horizontal variability in MCS (i.e., between sites of corresponding elevation in different transects, mainly due to differences in the composition of bacterial PLFAs, but also a systematic altitudinal shift in MCS related to different habitat preferences of fungi and bacteria, which resulted in high fungi-to-bacteria ratios at the most elevated sites. The biological soil crusts on these most elevated, unvegetated sites can host microbial assemblages of a size and activity comparable to those of the arctic tundra ecosystem. The key environmental factors determining horizontal and vertical changes in soil microbial properties were soil pH, organic carbon content, soil moisture and Mg2+ availability.

  6. Soil-mediated filtering organizes tree assemblages in regenerating tropical forests

    NARCIS (Netherlands)

    Pinho, Bruno Ximenes; Melo, de Felipe Pimentel Lopes; Arroyo-Rodríguez, Víctor; Pierce, Simon; Lohbeck, Madelon; Tabarelli, Marcelo

    2018-01-01

    Secondary forests are increasingly dominant in human-modified tropical landscapes, but the drivers of forest recovery remain poorly understood. Soil conditions influence plant community composition, and are expected to change over a gradient of succession. However, the role of soil conditions as

  7. [Spatial characteristics of soil organic carbon and nitrogen storages in Songnen Plain maize belt].

    Science.gov (United States)

    Zhang, Chun-Hua; Wang, Zong-Ming; Ren, Chun-Ying; Song, Kai-Shan; Zhang, Bai; Liu, Dian-Wei

    2010-03-01

    By using the data of 382 typical soil profiles from the second soil survey at national and county levels, and in combining with 1:500000 digital soil maps, a spatial database of soil profiles was established. Based on this, the one meter depth soil organic carbon and nitrogen storage in Songnen Plain maize belt of China was estimated, with the spatial characteristics of the soil organic carbon and nitrogen densities as well as the relationships between the soil organic carbon and nitrogen densities and the soil types and land use types analyzed. The soil organic carbon and nitrogen storage in the maize belt was (163.12 +/- 26.48) Tg and (9.53 +/- 1.75) Tg, respectively, mainly concentrated in meadow soil, chernozem, and black soil. The soil organic carbon and nitrogen densities were 5.51-25.25 and 0.37-0.80 kg x m(-2), respectively, and the C/N ratio was about 7.90 -12.67. The eastern and northern parts of the belt had much higher carbon and nitrogen densities than the other parts of the belt, and upland soils had the highest organic carbon density [(19.07 +/- 2.44) kg x m(-2)], forest soils had the highest nitrogen density [(0.82 +/- 0.25) kg x m(-2)], while lowland soils had the lower organic carbon and nitrogen densities.

  8. The second wave of earthworm invasion: soil organic matter dynamics from the stable isotope perspective

    Science.gov (United States)

    Chang, C.; Szlavecz, K. A.; Bernard, M.; Pitz, S.

    2013-12-01

    airtight chamber. Stable isotope mass balance calculation is used to estimate the recovery of litter-derived carbon from three pools (earthworm tissue, SOM, remaining litter), the loss of litter-derived carbon through soil respiration, and the contribution of different carbon sources to soil CO2 efflux in different earthworm treatments. Our results show that earthworm species recognized as 'soil feeders' have 13C and 15N values that are 1.2‰ and 3.8‰ higher than those of 'litter feeders', and 15N also differ significantly amount different soil feeders, suggesting different food resource usage even within the same functional group. There are strong species effects on both leaf litter disappearance rate and CO2 efflux rate, both being high when Amynthas earthworms are present. Our results suggest that changing earthworm species composition leads to changing resource use, which alters the fate of organic carbon in the forest floor and soil and could potentially affect long-term SOM dynamics in temperate forests.

  9. Electroremediation of PCB contaminated soil combined with iron nanoparticles: Effect of the soil type

    DEFF Research Database (Denmark)

    Gomes, Helena I.; Dias-Ferreira, Celia; Ottosen, Lisbeth M.

    2015-01-01

    Polychlorinated biphenyls (PCB) are carcinogenic and persistent organic pollutants that accumulate in soils and sediments. Currently, there is no cost-effective and sustainable remediation technology for these contaminants. In this work, a new combination of electrodialytic remediation and zero...... nanoparticles. Remediation experiments are made with two different historically PCB contaminated soils, which differ in both soil composition and contamination source. Soil 1 is a mix of soils with spills of transformer oils, while Soil 2 is a superficial soil from a decommissioned school where PCB were used...... as windows sealants. Saponin, a natural surfactant, was also tested to increase the PCB desorption from soils and enhance dechlorination. Remediation of Soil 1 (with highest pH, carbonate content, organic matter and PCB concentrations) obtained the maximum 83% and 60% PCB removal with the two...

  10. Primary immigration and succession of soil organisms on reclaimed opencast coal mining areas in eastern Germany

    Energy Technology Data Exchange (ETDEWEB)

    Wanner, M.; Dunger, W. [Staatliches Museum Naturkunde, Gorlitz (Germany)

    2002-07-01

    Immigration to and colonisation of recultivated opencast coal mining areas by soil organisms were investigated in eastern Germany during the period 1996-1998 in freshly exposed substrates (immigration test) and two up to 46-year-old afforested mine soils (stage-dependent succession). The results indicate that immigration by air is characteristic for protists, soil microarthropods and spiders, while active locomotion is more important for the soil macrofauna. Testate amoebae assemblages showed no evident differences between 30-37-year-old Tertiary afforestations (ash-ameliorated, pyrite-rich, low soil pH) and 46-year-old Pleistocene sites (liming, low pyrite content, moderate soil pH), while comparisons in soil animals revealed pronounced differences in abundance, biomass and species composition. Generally, all investigated soil animal groups indicated taxon-specific immigration and colonisation strategies with pronounced site preferences, dependent on substrate quality, age and afforestation. Within 40 years, a consistent trend is visible from an open pioneer to a woodland community. Furthermore, it was demonstrated that long-term investigations as well as numerous taxa of different trophic levels are essential for a comprehensive evaluation of recultivated mine dumps.

  11. Soil-Water Repellency Characteristic Curves for Soil Profiles with Organic Carbon Gradients

    DEFF Research Database (Denmark)

    Wijewardana, Nadeeka Senani; Muller, Karin; Moldrup, Per

    2016-01-01

    Soil water repellency (SWR) of soils is a property with significant consequences for agricultural water management, water infiltration, contaminant transport, and for soil erosion. It is caused by the presence of hydrophobic agents on mineral grain surfaces. Soils were samples in different depths......, and the sessile drop method (SDM). The aim to (i) compare the methods, (ii) characterize the soil-water repellency characteristic curves (SWRCC) being SWR as a function of the volumetric soil-water content (θ) or matric potential (ψ), and (iii) find relationships between SWRCC parameters and SOC content. The WDPT...... at three forest sites in Japan and three pasture sites in New Zealand, covering soil organic carbon (SOC) contents between 1 and 26%. The SWR was measured over a range of water contents by three common methods; the water drop penetration time (WDPT) test, the molarity of an ethanol droplet (MED) method...

  12. [Characteristics of soil organic carbon and enzyme activities in soil aggregates under different vegetation zones on the Loess Plateau].

    Science.gov (United States)

    Li, Xin; Ma, Rui-ping; An, Shao-shan; Zeng, Quan-chao; Li, Ya-yun

    2015-08-01

    In order to explore the distribution characteristics of organic carbon of different forms and the active enzymes in soil aggregates with different particle sizes, soil samples were chosen from forest zone, forest-grass zone and grass zone in the Yanhe watershed of Loess Plateau to study the content of organic carbon, easily oxidized carbon, and humus carbon, and the activities of cellulase, β-D-glucosidase, sucrose, urease and peroxidase, as well as the relations between the soil aggregates carbon and its components with the active soil enzymes were also analyzed. It was showed that the content of organic carbon and its components were in order of forest zone > grass zone > forest-grass zone, and the contents of three forms of organic carbon were the highest in the diameter group of 0.25-2 mm. The content of organic carbon and its components, as well as the activities of soil enzymes were higher in the soil layer of 0-10 cm than those in the 10-20 cm soil layer of different vegetation zones. The activities of cellulase, β-D-glucosidase, sucrose and urease were in order of forest zone > grass zone > forest-grass zone. The peroxidase activity was in order of forest zone > forest-grass zone > grass zone. The activities of various soil enzymes increased with the decreasing soil particle diameter in the three vegetation zones. The activities of cellulose, peroxidase, sucrose and urease had significant positive correlations with the contents of various forms of organic carbon in the soil aggregates.

  13. Physical properties of organic soils. Chapter 5.

    Science.gov (United States)

    Elon S. Verry; Don H. Boelter; Juhani Paivanen; Dale S. Nichols; Tom Malterer; Avi Gafni

    2011-01-01

    Compared with research on mineral soils, the study of the physical properties of organic soils in the United States is relatively new. A comprehensive series of studies on peat physical properties were conducted by Don Boelter (1959-1975), first at the Marcell Experimental Forest (MEF) and later throughout the northern Lakes States to investigate how to express bulk...

  14. Soil organic carbon pools and stocks in permafrost-affected soils on the tibetan plateau.

    Directory of Open Access Journals (Sweden)

    Corina Dörfer

    Full Text Available The Tibetan Plateau reacts particularly sensitively to possible effects of climate change. Approximately two thirds of the total area is affected by permafrost. To get a better understanding of the role of permafrost on soil organic carbon pools and stocks, investigations were carried out including both discontinuous (site Huashixia, HUA and continuous permafrost (site Wudaoliang, WUD. Three organic carbon fractions were isolated using density separation combined with ultrasonic dispersion: the light fractions (1.6 g cm(-3 of mineral associated organic matter (MOM. The fractions were analyzed for C, N, and their portion of organic C. FPOM contained an average SOC content of 252 g kg(-1. Higher SOC contents (320 g kg(-1 were found in OPOM while MOM had the lowest SOC contents (29 g kg(-1. Due to their lower density the easily decomposable fractions FPOM and OPOM contribute 27% (HUA and 22% (WUD to the total SOC stocks. In HUA mean SOC stocks (0-30 cm depth account for 10.4 kg m(-2, compared to 3.4 kg m(-2 in WUD. 53% of the SOC is stored in the upper 10 cm in WUD, in HUA only 39%. Highest POM values of 36% occurred in profiles with high soil moisture content. SOC stocks, soil moisture and active layer thickness correlated strongly in discontinuous permafrost while no correlation between SOC stocks and active layer thickness and only a weak relation between soil moisture and SOC stocks could be found in continuous permafrost. Consequently, permafrost-affected soils in discontinuous permafrost environments are susceptible to soil moisture changes due to alterations in quantity and seasonal distribution of precipitation, increasing temperature and therefore evaporation.

  15. Study on Dynamic Characteristics of Heavy Machine Tool-Composite Pile Foundation-Soil

    Directory of Open Access Journals (Sweden)

    CAI Li-Gang

    2014-09-01

    Full Text Available Heavy duty computer numerical control machine tools have characteristics of large self-weight, load and. The insufficiency of foundation bearing capacity leads to deformation of lathe bed, which effects machining accuracy. A combined-layer foundation model is created to describe the pile group foundation of multi-soil layer in this paper. Considering piles and soil in pile group as transversely isotropic material, equivalent constitutive relationship of composite foundation is constructed. A mathematical model is established by the introduction of boundary conditions, which is based on heavy duty computer numerical control machine tools-composite pile foundation-soil interaction system. And then, the response of different soil and pile depth is studied by a case. The model improves motion accuracy of machine tools.

  16. Scale-dependent variation in nitrogen cycling and soil fungal communities along gradients of forest composition and age in regenerating tropical dry forests.

    Science.gov (United States)

    Waring, Bonnie G; Adams, Rachel; Branco, Sara; Powers, Jennifer S

    2016-01-01

    Rates of ecosystem nitrogen (N) cycling may be mediated by the presence of ectomycorrhizal fungi, which compete directly with free-living microbes for N. In the regenerating tropical dry forests of Central America, the distribution of ectomycorrhizal trees is affected by succession and soil parent material, both of which may exert independent influence over soil N fluxes. In order to quantify these interacting controls, we used a scale-explicit sampling strategy to examine soil N cycling at scales ranging from the microsite to ecosystem level. We measured fungal community composition, total and inorganic N pools, gross proteolytic rate, net N mineralization and microbial extracellular enzyme activity at multiple locations within 18 permanent plots that span dramatic gradients of soil N concentration, stand age and forest composition. The ratio of inorganic to organic N cycling was correlated with variation in fungal community structure, consistent with a strong influence of ectomycorrhiza on ecosystem-scale N cycling. However, on average, > 61% of the variation in soil biogeochemistry occurred within plots, and the effects of forest composition were mediated by this local-scale heterogeneity in total soil N concentrations. These cross-scale interactions demonstrate the importance of a spatially explicit approach towards an understanding of controls on element cycling. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  17. The origin of lead in the organic horizon of tundra soils: Atmospheric deposition, plant translocation from the mineral soil or soil mineral mixing?

    International Nuclear Information System (INIS)

    Klaminder, Jonatan; Farmer, John G.; MacKenzie, Angus B.

    2011-01-01

    Knowledge of the anthropogenic contribution to lead (Pb) concentrations in surface soils in high latitude ecosystems is central to our understanding of the extent of atmospheric Pb contamination. In this study, we reconstructed fallout of Pb at a remote sub-arctic region by using two ombrotrophic peat cores and assessed the extent to which this airborne Pb is able to explain the isotopic composition ( 206 Pb/ 207 Pb ratio) in the O-horizon of tundra soils. In the peat cores, long-range atmospheric fallout appeared to be the main source of Pb as indicated by temporal trends that followed the known European pollution history, i.e. accelerated fallout at the onset of industrialization and peak fallout around the 1960s-70s. The Pb isotopic composition of the O-horizon of podzolic tundra soil ( 206 Pb/ 207 Pb = 1.170 ± 0.002; mean ± SD) overlapped with that of the peat ( 206 Pb/ 207 Pb = 1.16 ± 0.01) representing a proxy for atmospheric aerosols, but was clearly different from that of the parent soil material ( 206 Pb/ 207 Pb = 1.22-1.30). This finding indicated that long-range fallout of atmospheric Pb is the main driver of Pb accumulation in podzolic tundra soil. In O-horizons of tundra soil weakly affected by cryoturbation (cryosols) however, the input of Pb from the underlying mineral soil increased as indicated by 206 Pb/ 207 Pb ratios of up to 1.20, a value closer to that of local soil minerals. Nevertheless, atmospheric Pb appeared to be the dominant source in this soil compartment. We conclude that Pb concentrations in the O-horizon of studied tundra soils - despite being much lower than in boreal soils and representative for one of the least exposed sites to atmospheric Pb contaminants in Europe - are mainly controlled by atmospheric inputs from distant anthropogenic sources. - Highlights: → We used Pb isotopic composition to aid interpretation of Pb profiles in tundra soils. → Ombrotrophic peat cores were used as records of atmospheric inputs of Pb.

  18. Drivers of soil organic matter vulnerability to climate change. Part I: Laboratory incubations of Swiss forest soils and radiocarbon analysis

    Science.gov (United States)

    González Domínguez, Beatriz; Studer, Mirjam S.; Niklaus, Pascal A.; Haghipour, Negar; McIntyre, Cameron; Wacker, Lukas; Zimmermann, Stephan; Walthert, Lorenz; Hagedorn, Frank; Abiven, Samuel

    2016-04-01

    Given the key role of soil organic carbon (SOC) on climate and greenhouse gas regulation, there is an increasing need to incorporate the carbon (C) feedback between SOC and the atmosphere into earth system models. The evaluation of these models points towards uncertainties on the response of CO2-C fluxes, derived from the decomposition of SOC, to the influence of controls/drivers. SOC vulnerability refers to the likelihood of losing previously stabilized soil organic matter, by the effect of environmental factors. The objective of this study is to produce a SOC vulnerability ranking of soils and to provide new insights into the influence of environmental and soil properties controls. Research on SOC vulnerability tends to focus on climatic controls and neglect the effect of other factors, such as soil geochemistry and mineralogy, on C stabilization/de-stabilization processes. In this work, we hypothesized that climate (mean annual temperature and soil moisture status proxy at the research sites in the period 1981-2010), soil (pH and % clay) and terrain (slope gradient and orientation) characteristics are the main controls of the CO2-C fluxes from SOC. Following a statistics-based approach, we selected 54 forest sites across Switzerland, which cover a broad spectrum of values for the hypothesized controls. Then, we selected the study sites so that the controls are orthogonal to each other; thus, their effect was not confounded. At each site, we collected three non-overlapping topsoil (i.e. 20 cm) composites within 40 x 40 m2 plots. In the laboratory, we sieved fresh soils at 2 mm and run a 2-weeks pre-incubation, before beginning a 6-months aerobic soil incubation under controlled conditions of moisture and temperature. Periodically, we collected NaOH (1M) traps containing the CO2-C derived from microbial heterotrophic respiration. We calculated the cumulative CO2-C respired and the one-pool SOC decomposition rates from the 54 forest sites, and linked these data to

  19. Impact of carbonaceous materials in soil on the transport of soil-bound PAHs during rainfall-runoff events

    International Nuclear Information System (INIS)

    Luo, Xiaolin; Zheng, Yi; Wu, Bin; Lin, Zhongrong; Han, Feng; Zhang, Wei; Wang, Xuejun

    2013-01-01

    Polycyclic Aromatic Hydrocarbons (PAHs) transported from contaminated soils by surface runoff pose significant risk for aquatic ecosystems. Based on a rainfall-runoff simulation experiment, this study investigated the impact of carbonaceous materials (CMs) in soil, identified by organic petrology analysis, on the transport of soil-bound PAHs under rainfall conditions. The hypothesis that composition of soil organic matter significantly impacts the enrichment and transport of PAHs was proved. CMs in soil, varying significantly in content, mobility and adsorption capacity, act differently on the transport of PAHs. Anthropogenic CMs like black carbon (BC) largely control the transport, as PAHs may be preferentially attached to them. Eventually, this study led to a rethink of the traditional enrichment theory. An important implication is that CMs in soil have to be explicitly considered to appropriately model the nonpoint source pollution of PAHs (possibly other hydrophobic chemicals as well) and assess its environmental risk. -- Highlights: •Composition of SOM significantly impacts the enrichment and transport of PAHs. •Anthropogenic carbonaceous materials in soil largely control the transport of PAHs. •The classic enrichment theory is invalid if anthropogenic CMs are abundant in the soil. •Organic petrology analysis introduced to study the fate and transport of PAHs. -- Anthropogenic carbonaceous materials in soil, especially black carbon, largely control the transport of soil-bound PAHs during rainfall-runoff events

  20. Soil biochar amendment shapes the composition of N2O-reducing microbial communities.

    Science.gov (United States)

    Harter, Johannes; Weigold, Pascal; El-Hadidi, Mohamed; Huson, Daniel H; Kappler, Andreas; Behrens, Sebastian

    2016-08-15

    Soil biochar amendment has been described as a promising tool to improve soil quality, sequester carbon, and mitigate nitrous oxide (N2O) emissions. N2O is a potent greenhouse gas. The main sources of N2O in soils are microbially-mediated nitrogen transformation processes such as nitrification and denitrification. While previous studies have focused on the link between N2O emission mitigation and the abundance and activity of N2O-reducing microorganisms in biochar-amended soils, the impact of biochar on the taxonomic composition of the nosZ gene carrying soil microbial community has not been subject of systematic study to date. We used 454 pyrosequencing in order to study the microbial diversity in biochar-amended and biochar-free soil microcosms. We sequenced bacterial 16S rRNA gene amplicons as well as fragments of common (typical) nosZ genes and the recently described 'atypical' nosZ genes. The aim was to describe biochar-induced shifts in general bacterial community diversity and taxonomic variations among the nosZ gene containing N2O-reducing microbial communities. While soil biochar amendment significantly altered the 16S rRNA gene-based community composition and structure, it also led to the development of distinct functional traits capable of N2O reduction containing typical and atypical nosZ genes related to nosZ genes found in Pseudomonas stutzeri and Pedobacter saltans, respectively. Our results showed that biochar amendment can affect the relative abundance and taxonomic composition of N2O-reducing functional microbial traits in soil. Thus these findings broaden our knowledge on the impact of biochar on soil microbial community composition and nitrogen cycling. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Influence of Scots pine encroachment into alpine grassland in the quality and stability of soil organic matter aggregation

    Science.gov (United States)

    Ortiz, Carlos; Díaz-Pinés, Eugenio; Benito, Marta; José Fernández, María; Rubio, Agustín

    2013-04-01

    Ecotone areas are dynamic zones potentially suitable for detecting ecosystem sensitivity to climate change effects. Climate change scenarios proposed by IPCC predict a temperature increase in Mediterranean areas with the consequent altitudinal advance of Scots pine treeline (Pinus sylvestris L.) at the extent of grassland-shrubland areas. Therefore, variations in physical, chemical and biological properties of soils due to plant dynamics are expected. We present a study located in the grassland-forest ecotone of Scots pine on a Mediterranean mountain in Central Spain, considering three different vegetation types: high mountain grassland-shrubland, shrubland-Scots pine high mountain forest and Scots pine mountain forest. We worked on the hypothesis that different plant species compositions influence both the size distribution and aggregate protection of the organic carbon (C), as a result of the different quality of C inputs to the soil from different vegetation types. To test this assumption, topsoil samples were firstly separated into four aggregate fractions (6-2 mm, 2-0.250 mm, 0.250-0.053 mm and centrifuging and decanting the supernatants; and thirdly, different iPOM (coarse iPOM and fine iPOM) and mineral associated soil organic C were released from each remaining aggregate fraction by sonication at 300 J ml-1 and further quantified by wet sieving. We expect differences between light fraction, different iPOM and mineral associated soil organic C from the different aggregates fractions obtained among vegetation types as a result of different quality and quantity organic matter inputs to the soil. Thus, we will be able to predict (i) the evolution of protected soil organic matter with the encroachment of Scots pine on Mediterranean mountains due to climate change effects, (ii) the rate of macroaggregate formation and degradation in those vegetation areas, and (iii) whether they will behave as source or sink of atmospheric C.

  2. An isotopic investigation of the temperature response of young and old soil organic matter respiration

    Science.gov (United States)

    Burns, Nancy; Cloy, Joanna; Garnett, Mark; Reay, David; Smith, Keith; Otten, Wilfred

    2010-05-01

    The effect of temperature on rates of soil respiration is critical to our understanding of the terrestrial carbon cycle and potential feedbacks to climate change. The relative temperature sensitivity of labile and recalcitrant soil organic matter (SOM) is still controversial; different studies have produced contrasting results, indicating limited understanding of the underlying relationships between stabilisation processes and temperature. Current global carbon cycle models still rely on the assumption that SOM pools with different decay rates have the same temperature response, yet small differences in temperature response between pools could lead to very different climate feedbacks. This study examined the temperature response of soil respiration and the age of soil carbon respired from radiocarbon dated fractions of SOM (free, intra-aggregate and mineral-bound) and whole soils (organic and mineral layers). Samples were collected from a peaty gley soil from Harwood Forest, Northumberland, UK. SOM fractions were isolated from organic layer (5 - 17 cm) material using high density flotation and ultrasonic disaggregation - designated as free (aggregate (aggregates > 1.8 g cm-3) and mineral-bound (> 1.8 g cm-3) SOM. Fractions were analysed for chemical composition (FTIR, CHN analysis, ICP-OES), 14C (AMS), δ13C and δ15N (MS) and thermal properties (DSC). SOM fractions and bulk soil from the organic layer and the mineral layer (20 - 30 cm) were incubated in sealed vessels at 30 ° C and 10 ° C for 3 or 9 months to allow accumulation of CO2 sufficient for sampling. Accumulated respired CO2 samples were collected on zeolite molecular sieve cartridges and used for AMS radiocarbon dating. In parallel, material from the same fractions and layers were incubated at 10 ° C, 15 ° C, 25 ° C and 30 ° C for 6 months and sampled weekly for CO2 flux measurements using GC chromatography. Initial data have shown radiocarbon ages ranging from modern to 219 y BP in bulk soil from

  3. Physicochemical characteristics of communal rangeland soils along ...

    African Journals Online (AJOL)

    This study investigated the relative association of surface (0–20 cm) soil physicochemical properties, viz. electrical conductivity, cation exchange capacity (CEC), soil organic carbon, available phosphorus, particle size composition, soil aggregate stability and microbial respiration, along a toposequence in two vegetation ...

  4. Radiation resistant organic composites for superconducting fusion magnets

    International Nuclear Information System (INIS)

    Nishijima, S.; Okada, T.

    1993-01-01

    Organic composite materials (usually reinforced by glas fibers: GFRP) are to be used in fusion superconducting magnets as insulating and/or structural materials. The fusion superconducting magnets are operated under radiation environments and hence the radiation induced degradation of magnet components is ought to be estimated. Among the components the organic composite materials were evaluated to be the most radiation sensitive. Consequently the development of radiation resistant organic composite materials is thought one of the 'key' technologies for fusion superconducting magnets. The mechanism of radiation-induced degradation was studied and the degradation of interlaminar shear strength (ILSS) was found to be the intrinsic phenomenon which controlled the overall degradation of organic composite materials. The degradation of ILSS was studied changing matrix resin, reinforcement and type of fabrics. The possible combination of the organic composites for the fusion superconducting magnet will be discussed. (orig.)

  5. Impacts of soil redistribution on the transport and fate of organic carbon in loess soils

    NARCIS (Netherlands)

    Wang, X.

    2014-01-01

    Soil erosion is an important environmental process leading to loss of topsoil including carbon (C) and nutrients, reducing soil quality and loss of biomass production. So far, the fate of soil organic carbon (SOC) in eroding landscapes is not yet fully understood and remains an important uncertainty

  6. Cosorption study of organic pollutants and dissolved organic matter in a soil.

    Science.gov (United States)

    Flores-Céspedes, F; Fernández-Pérez, M; Villafranca-Sánchez, M; González-Pradas, E

    2006-08-01

    In this study we have evaluated the effects of dissolved organic matter (DOM) on sorption of imidacloprid, 3,4-dichloroaniline (3,4-DCA) and 4-bromoaniline (4-BA) on a typical calcareous soil (Luvic Xerosol) from south-eastern Spain. Two different types of DOM were used, that is to say, dissolved natural organic matter extracts from a commercial peat (DNOM) and a high-purity tannic acid (TA) solution. The experiments were carried out in a 0.01 M CaCl2 aqueous medium at 25 degrees C. The results indicated that the presence of both DNOM and TA, over a concentration range of 15-100 mg L(-1), produced an increase in the amount of 3,4-DCA and 4-BA sorbed and a decrease in the amount of imidacloprid retained on the soil studied. A modified distribution coefficient, K(doc), has been proposed as a safer parameter for soil sorption predictions of organic pollutants and it could be of help to model the fate of these in the environment.

  7. ORCHIDEE-SOM: modeling soil organic carbon (SOC) and dissolved organic carbon (DOC) dynamics along vertical soil profiles in Europe

    Science.gov (United States)

    Camino-Serrano, Marta; Guenet, Bertrand; Luyssaert, Sebastiaan; Ciais, Philippe; Bastrikov, Vladislav; De Vos, Bruno; Gielen, Bert; Gleixner, Gerd; Jornet-Puig, Albert; Kaiser, Klaus; Kothawala, Dolly; Lauerwald, Ronny; Peñuelas, Josep; Schrumpf, Marion; Vicca, Sara; Vuichard, Nicolas; Walmsley, David; Janssens, Ivan A.

    2018-03-01

    Current land surface models (LSMs) typically represent soils in a very simplistic way, assuming soil organic carbon (SOC) as a bulk, and thus impeding a correct representation of deep soil carbon dynamics. Moreover, LSMs generally neglect the production and export of dissolved organic carbon (DOC) from soils to rivers, leading to overestimations of the potential carbon sequestration on land. This common oversimplified processing of SOC in LSMs is partly responsible for the large uncertainty in the predictions of the soil carbon response to climate change. In this study, we present a new soil carbon module called ORCHIDEE-SOM, embedded within the land surface model ORCHIDEE, which is able to reproduce the DOC and SOC dynamics in a vertically discretized soil to 2 m. The model includes processes of biological production and consumption of SOC and DOC, DOC adsorption on and desorption from soil minerals, diffusion of SOC and DOC, and DOC transport with water through and out of the soils to rivers. We evaluated ORCHIDEE-SOM against observations of DOC concentrations and SOC stocks from four European sites with different vegetation covers: a coniferous forest, a deciduous forest, a grassland, and a cropland. The model was able to reproduce the SOC stocks along their vertical profiles at the four sites and the DOC concentrations within the range of measurements, with the exception of the DOC concentrations in the upper soil horizon at the coniferous forest. However, the model was not able to fully capture the temporal dynamics of DOC concentrations. Further model improvements should focus on a plant- and depth-dependent parameterization of the new input model parameters, such as the turnover times of DOC and the microbial carbon use efficiency. We suggest that this new soil module, when parameterized for global simulations, will improve the representation of the global carbon cycle in LSMs, thus helping to constrain the predictions of the future SOC response to global

  8. Dynamic aspects of soil organic matter and its relationship to the physical properties and fertility of soils

    International Nuclear Information System (INIS)

    Wagner, G.H.

    1980-01-01

    Soil organic matter plays a critical role in determining the physical, chemical, and biological nature of soils. Its dynamic nature is explored with reference to the cycling of C and N in the biosphere. Optimum soil structure is developed under a grass sod, but adequate water stable aggregates can be maintained under proper cultivation to ensure deep root penetration, rapid water infiltration for storage in the rooting zone, and the prevention of surface crusting. Perhaps the most important role of organic material is its prevention of soil erosion by directly stabilizing the soil during the growing season, providing residues for protection between crops, and improving surface aggregation to make the soil less subject to erosion. (author)

  9. Self-organizing biochemical cycle in dynamic feedback with soil structure

    Science.gov (United States)

    Vasilyeva, Nadezda; Vladimirov, Artem; Smirnov, Alexander; Matveev, Sergey; Tyrtyshnikov, Evgeniy; Yudina, Anna; Milanovskiy, Evgeniy; Shein, Evgeniy

    2016-04-01

    In the present study we perform bifurcation analysis of a physically-based mathematical model of self-organized structures in soil (Vasilyeva et al., 2015). The state variables in this model included microbial biomass, two organic matter types, oxygen, carbon dioxide, water content and capillary pore size. According to our previous experimental studies, organic matter affinity to water is an important property affecting soil structure. Therefore, organic matter wettability was taken as principle distinction between organic matter types in this model. It considers general known biological feedbacks with soil physical properties formulated as a system of parabolic type non-linear partial differential equations with elements of discrete modeling for water and pore formation. The model shows complex behavior, involving emergence of temporal and spatial irregular auto-oscillations from initially homogeneous distributions. The energy of external impact on a system was defined by a constant oxygen level on the boundary. Non-linear as opposed to linear oxygen diffusion gives possibility of modeling anaerobic micro-zones formation (organic matter conservation mechanism). For the current study we also introduced population competition of three different types of microorganisms according to their mobility/feeding (diffusive, moving and fungal growth). The strongly non-linear system was solved and parameterized by time-optimized algorithm combining explicit and implicit (matrix form of Thomas algorithm) methods considering the time for execution of the evaluated time-step according to accuracy control. The integral flux of the CO2 state variable was used as a macroscopic parameter to describe system as a whole and validation was carried out on temperature series of moisture dependence for soil heterotrophic respiration data. Thus, soil heterotrophic respiration can be naturally modeled as an integral result of complex dynamics on microscale, arising from biological processes

  10. Using biochar for remediation of soils contaminated with heavy metals and organic pollutants.

    Science.gov (United States)

    Zhang, Xiaokai; Wang, Hailong; He, Lizhi; Lu, Kouping; Sarmah, Ajit; Li, Jianwu; Bolan, Nanthi S; Pei, Jianchuan; Huang, Huagang

    2013-12-01

    Soil contamination with heavy metals and organic pollutants has increasingly become a serious global environmental issue in recent years. Considerable efforts have been made to remediate contaminated soils. Biochar has a large surface area, and high capacity to adsorb heavy metals and organic pollutants. Biochar can potentially be used to reduce the bioavailability and leachability of heavy metals and organic pollutants in soils through adsorption and other physicochemical reactions. Biochar is typically an alkaline material which can increase soil pH and contribute to stabilization of heavy metals. Application of biochar for remediation of contaminated soils may provide a new solution to the soil pollution problem. This paper provides an overview on the impact of biochar on the environmental fate and mobility of heavy metals and organic pollutants in contaminated soils and its implication for remediation of contaminated soils. Further research directions are identified to ensure a safe and sustainable use of biochar as a soil amendment for remediation of contaminated soils.

  11. Molecular C dynamics downstream: the biochemical decomposition sequence and its impact on soil organic matter structure and function.

    Science.gov (United States)

    Grandy, A Stuart; Neff, Jason C

    2008-10-15

    Advances in spectroscopic and other chemical methods have greatly enhanced our ability to characterize soil organic matter chemistry. As a result, the molecular characteristics of soil C are now known for a range of ecosystems, soil types, and management intensities. Placing this knowledge into a broader ecological and management context is difficult, however, and remains one of the fundamental challenges of soil organic matter research. Here we present a conceptual model of molecular soil C dynamics to stimulate inter-disciplinary research into the ecological implications of molecular C turnover and its management- and process-level controls. Our model describes three properties of soil C dynamics: 1) soil size fractions have unique molecular patterns that reflect varying degrees of biological and physical control over decomposition; 2) there is a common decomposition sequence independent of plant inputs or other ecosystem properties; and 3) molecular decomposition sequences, although consistent, are not uniform and can be altered by processes that accelerate or slow the microbial transformation of specific molecules. The consequences of this model include several key points. First, lignin presents a constraint to decomposition of plant litter and particulate C (>53 microm) but exerts little influence on more stable mineral-associated soil fractions stabilized onto mineral fractions has a distinct composition related more to microbially processed organic matter than to plant-related compounds. Third, disturbances, such as N fertilization and tillage, which alter decomposition rates, can have "downstream effects"; that is, a disturbance that directly alters the molecular dynamics of particulate C may have a series of indirect effects on C stabilization in silt and clay fractions.

  12. Organic carbon stocks and sequestration rates of forest soils in Germany.

    Science.gov (United States)

    Grüneberg, Erik; Ziche, Daniel; Wellbrock, Nicole

    2014-08-01

    The National Forest Soil Inventory (NFSI) provides the Greenhouse Gas Reporting in Germany with a quantitative assessment of organic carbon (C) stocks and changes in forest soils. Carbon stocks of the organic layer and the mineral topsoil (30 cm) were estimated on the basis of ca. 1.800 plots sampled from 1987 to 1992 and resampled from 2006 to 2008 on a nationwide grid of 8 × 8 km. Organic layer C stock estimates were attributed to surveyed forest stands and CORINE land cover data. Mineral soil C stock estimates were linked with the distribution of dominant soil types according to the Soil Map of Germany (1 : 1 000 000) and subsequently related to the forest area. It appears that the C pool of the organic layer was largely depending on tree species and parent material, whereas the C pool of the mineral soil varied among soil groups. We identified the organic layer C pool as stable although C was significantly sequestered under coniferous forest at lowland sites. The mineral soils, however, sequestered 0.41 Mg C ha(-1) yr(-1) . Carbon pool changes were supposed to depend on stand age and forest transformation as well as an enhanced biomass input. Carbon stock changes were clearly attributed to parent material and soil groups as sandy soils sequestered higher amounts of C, whereas clayey and calcareous soils showed small gains and in some cases even losses of soil C. We further showed that the largest part of the overall sample variance was not explained by fine-earth stock variances, rather by the C concentrations variance. The applied uncertainty analyses in this study link the variability of strata with measurement errors. In accordance to other studies for Central Europe, the results showed that the applied method enabled a reliable nationwide quantification of the soil C pool development for a certain period. © 2014 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

  13. The Effect of paper mill waste and sewage sludge amendments on soil organic matter

    Science.gov (United States)

    Méndez, Ana; Barriga, Sandra; Guerrero, Francisca; Gascó, Gabriel

    2013-04-01

    In general, Mediterranean soils have low organic matter content, due to the climate characteristics of this region and inadequate land management. Traditionally, organic wastes such as manure are used as amendment in order to improve the soil quality, increasing soil fertility by the accumulation of nitrogen, phosphorus and other plant nutrients in the soil. In the last decade, other anthropogenic organic wastes such as sewage sludge or paper waste materials have been studied as soil amendments to improve physical, chemical and biological properties of soils. The objective of the present work was to study the influence of waste from a paper mill and sewage sludge amendments on soil organic matter. For this reason, soil organic matter evolution was studied using thermogravimetric analysis (TGA), the derivative (dTG) and differential thermal analysis (DTA). Thermal analytical techniques have the advantage of using full samples without pre-treatments and have been extensively used to study the evolution of organic matter in soils, to evaluate composting process or to study the evolution of organic matter of growing media.

  14. The Unified North American Soil Map and Its Implication on the Soil Organic Carbon Stock in North America

    Science.gov (United States)

    Wei, Y.; Liu, S.; Huntzinger, D. N.; Michalak, A. M.; Post, W. M.; Cook, R. B.; Schaefer, K. M.; Thornton, M.

    2014-12-01

    The Unified North American Soil Map (UNASM) was developed by Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP) to provide more accurate regional soil information for terrestrial biosphere modeling. The UNASM combines information from state-of-the-art US STATSGO2 and Soil Landscape of Canada (SLCs) databases. The area not covered by these datasets is filled by using the Harmonized World Soil Database version 1.21 (HWSD1.21). The UNASM contains maximum soil depth derived from the data source as well as seven soil attributes (including sand, silt, and clay content, gravel content, organic carbon content, pH, and bulk density) for the topsoil layer (0-30 cm) and the subsoil layer (30-100 cm), respectively, of the spatial resolution of 0.25 degrees in latitude and longitude. There are pronounced differences in the spatial distributions of soil properties and soil organic carbon between UNASM and HWSD, but the UNASM overall provides more detailed and higher-quality information particularly in Alaska and central Canada. To provide more accurate and up-to-date estimate of soil organic carbon stock in North America, we incorporated Northern Circumpolar Soil Carbon Database (NCSCD) into the UNASM. The estimate of total soil organic carbon mass in the upper 100 cm soil profile based on the improved UNASM is 365.96 Pg, of which 23.1% is under trees, 14.1% is in shrubland, and 4.6% is in grassland and cropland. This UNASM data has been provided as a resource for use in terrestrial ecosystem modeling of MsTMIP both for input of soil characteristics and for benchmarking model output.

  15. Effect of four herbicides on microbial population, soil organic matter ...

    African Journals Online (AJOL)

    The effect of four herbicides (atrazine, primeextra, paraquat and glyphosate) on soil microbial population, soil organic matter and dehydrogenase activity was assessed over a period of six weeks. Soil samples from cassava farms were treated with herbicides at company recommended rates. Soil dehydrogenase activity was ...

  16. Which soil tillage is better in terms of the soil organic matter and soil structure changes?

    Directory of Open Access Journals (Sweden)

    VLADIMÍR ŠIMANSKÝ

    2016-06-01

    Full Text Available This study was performed to evaluate effects of minimum (MT and conventional tillage (CT on soil organic matter and soil structure in haplic Chernozems and mollic Fluvisols. The content of soil organic carbon (Corg as well as parameters of stability and vulnerability of soil structure were quantified. The results showed that soil type had statistically significant influence on Corg. In haplic Chernozems the Corg content near the surface (0–0.1 m was significantly higher under MT (by 6% compared to CT, however, in layer 0–0.3 m under CT the average Corg content was by 16% higher than under MT. In mollic Fulvisols under MT, the average Corg content (17.5 ± 5.4 g*kg-1 was significantly less for the 0–0.3 m layer than the CT (22.7 ± 0.4 g*kg-1. In Chernozems, total content of water-stable micro-aggregates (WSAmi was higher in MT (90.8% than in CT (69.5%. In mollic Fluvisols, the average content of WSAmi was higher in CT (62.5% than in MT (53.2%. The low aggregate stability and the high structure vulnerability were reflected also due to the high contents of WSAmi in both soils. The stability of aggregates was a higher in mollic Fluvisols than in haplic Chernozems. In haplic Chernozems, better soil structure stability was under CT than MT, on the other hand, in mollic Fluvisols, the average value of coefficient of aggregate stability was lower by 32% in CT than MT.

  17. Organic vs. organic - soil arthropods as bioindicators of ecological sustainability in greenhouse system experiment under Mediterranean conditions.

    Science.gov (United States)

    Madzaric, Suzana; Ceglie, F G; Depalo, L; Al Bitar, L; Mimiola, G; Tittarelli, F; Burgio, G

    2017-11-23

    Organic greenhouse (OGH) production is characterized by different systems and agricultural practices with diverse environmental impact. Soil arthropods are widely used as bioindicators of ecological sustainability in open field studies, while there is a lack of research on organic production for protected systems. This study assessed the soil arthropod abundance and diversity over a 2-year crop rotation in three systems of OGH production in the Mediterranean. The systems under assessment differed in soil fertility management: SUBST - a simplified system of organic production, based on an input substitution approach (use of guano and organic liquid fertilizers), AGROCOM - soil fertility mainly based on compost application and agroecological services crops (ASC) cultivation (tailored use of cover crops) as part of crop rotation, and AGROMAN - animal manure and ASC cultivation as part of crop rotation. Monitoring of soil fauna was performed by using pitfall traps and seven taxa were considered: Carabidae, Staphylinidae, Araneae, Opiliones, Isopoda, Myriapoda, and Collembola. Results demonstrated high potential of ASC cultivation as a technique for beneficial soil arthropod conservation in OGH conditions. SUBST system was dominated by Collembola in all crops, while AGROMAN and AGROCOM had more balanced relative abundance of Isopoda, Staphylinidae, and Aranea. Opiliones and Myriapoda were more affected by season, while Carabidae were poorly represented in the whole monitoring period. Despite the fact that all three production systems are in accordance with the European Union regulation on organic farming, findings of this study displayed significant differences among them and confirmed the suitability of soil arthropods as bioindicators in protected systems of organic farming.

  18. Indexing Permafrost Soil Organic Matter Degradation Using High-Resolution Mass Spectrometry.

    Science.gov (United States)

    Mann, Benjamin F; Chen, Hongmei; Herndon, Elizabeth M; Chu, Rosalie K; Tolic, Nikola; Portier, Evan F; Roy Chowdhury, Taniya; Robinson, Errol W; Callister, Stephen J; Wullschleger, Stan D; Graham, David E; Liang, Liyuan; Gu, Baohua

    2015-01-01

    Microbial degradation of soil organic matter (SOM) is a key process for terrestrial carbon cycling, although the molecular details of these transformations remain unclear. This study reports the application of ultrahigh resolution mass spectrometry to profile the molecular composition of SOM and its degradation during a simulated warming experiment. A soil sample, collected near Barrow, Alaska, USA, was subjected to a 40-day incubation under anoxic conditions and analyzed before and after the incubation to determine changes of SOM composition. A CHO index based on molecular C, H, and O data was utilized to codify SOM components according to their observed degradation potentials. Compounds with a CHO index score between -1 and 0 in a water-soluble fraction (WSF) demonstrated high degradation potential, with a highest shift of CHO index occurred in the N-containing group of compounds, while similar stoichiometries in a base-soluble fraction (BSF) did not. Additionally, compared with the classical H:C vs O:C van Krevelen diagram, CHO index allowed for direct visualization of the distribution of heteroatoms such as N in the identified SOM compounds. We demonstrate that CHO index is useful not only in characterizing arctic SOM at the molecular level but also enabling quantitative description of SOM degradation, thereby facilitating incorporation of the high resolution MS datasets to future mechanistic models of SOM degradation and prediction of greenhouse gas emissions.

  19. Carbohydrates and thermal analysis reflects changes in soil organic matter stability after forest expansion on abandoned grassland

    Science.gov (United States)

    Guidi, Claudia; Vesterdal, Lars; Cannella, David; Leifeld, Jens; Gianelle, Damiano; Rodeghiero, Mirco

    2014-05-01

    Grassland abandonment, followed by progressive forest expansion, is the dominant land-use change in the Southern Alps, Europe. Land-use change can affect not only the amount of organic matter (OM) in soil but also its composition and stability. Our objective was to investigate changes in organic matter properties after forest expansion on abandoned grasslands, combining analysis of carbohydrates, indicative of labile OM compounds with prevalent plant or microbial origin, with thermal analysis. Thermal analysis was used as a rapid assessment method for the characterization of SOM stability. A land-use gradient was investigated in four land-use types in the subalpine area of Trentino region, Italy: i) managed grassland, mown and fertilized for the past 100 years; ii) grassland abandoned since 10 years, with sparse shrubs and Picea abies saplings; iii) early-stage forest, dominated by P. abies and established on a grassland abandoned around 1970; iv) old forest, dominated by Fagus sylvatica and P. abies. Mineral soil was sampled at three subplots in each land use type with eight soil cores, which were subsequently pooled by depth (0-5 cm, 5-10 cm, 10-20 cm). Sugars were extracted from bulk soil samples through acid hydrolysis with H2SO4 (0.5 M). The analytical composition of sugar monomers was performed with HPAEC technology (Dionex ICS5000), equipped with PAD-detection. Thermal stability was assessed with a differential scanning calorimeter DSC100, heating soil samples up to 600°C at a heating rate of 10°C min-1 in synthetic air. Peak height (W g OC-1) of 1st DSC exotherm, dominated by burning of labile OM compounds, was used as thermal stability index. In the abandoned grassland, carbohydrates compounds accounted for a greater proportion of soil OC than in other land use types. Microbially derived sugars, as rhamnose and galactose, were more abundant in managed and abandoned grasslands compared with early-stage and old forest. The amount of thermally labile sugars

  20. Application of compost for effective bioremediation of organic contaminants and pollutants in soil.

    Science.gov (United States)

    Kästner, Matthias; Miltner, Anja

    2016-04-01

    Soils contaminated with hazardous chemicals worldwide are awaiting remediation activities; bioremediation is often considered as a cost-effective remediation approach. Potential bioapproaches are biostimulation, e.g. by addition of nutrients, fertiliser and organic substrates, and bioaugmentation by addition of compound-degrading microbes or of organic amendments containing active microorganisms, e.g. activated sludge or compost. In most contaminated soils, the abundance of the intrinsic metabolic potential is too low to be improved by biostimulation alone, since the physical and chemical conditions in these soils are not conducive to biodegradation. In the last few decades, compost or farmyard manure addition as well as composting with various organic supplements have been found to be very efficient for soil bioremediation. In the present minireview, we provide an overview of the composting and compost addition approaches as 'stimulants' of natural attenuation. Laboratory degradation experiments are often biased either by not considering the abiotic factors or by focusing solely on the elimination of the chemicals without taking the biotic factors and processes into account. Therefore, we first systemise the concepts of composting and compost addition, then summarise the relevant physical, chemical and biotic factors and mechanisms for improved contaminant degradation triggered by compost addition. These factors and mechanisms are of particular interest, since they are more relevant and easier to determine than the composition of the degrading community, which is also addressed in this review. Due to the mostly empirical knowledge and the nonstandardised biowaste or compost materials, the field use of these approaches is highly challenging, but also promising. Based on the huge metabolic diversity of microorganisms developing during the composting processes, a highly complex metabolic diversity is established as a 'metabolic memory' within developing and mature