WorldWideScience

Sample records for soil increased significantly

  1. Application of Bioorganic Fertilizer Significantly Increased Apple Yields and Shaped Bacterial Community Structure in Orchard Soil.

    Science.gov (United States)

    Wang, Lei; Li, Jing; Yang, Fang; E, Yaoyao; Raza, Waseem; Huang, Qiwei; Shen, Qirong

    2017-02-01

    and Rhodospirillaceae, were found to be the significantly increased by the BOF addition and the genus Lysobacter may identify members of this group effective in biological control-based plant disease management and the members of family Rhodospirillaceae had an important role in fixing molecular nitrogen. These results strengthen the understanding of responses to the BOF and possible interactions within bacterial communities in soil that can be associated with disease suppression and the accumulation of carbon and nitrogen. The increase of apple yields after the application of BOF might be attributed to the fact that the application of BOF increased SOM, and soil total nitrogen, and changed the bacterial community by enriching Rhodospirillaceae, Alphaprotreobateria, and Proteobacteria.

  2. Significance of foundation-soil separation in dynamic soil-structure interaction

    Science.gov (United States)

    Spyrakos, Constantine C.; Patel, P. N.

    1987-01-01

    THe dynamic response of flexible surface strip-foundations allowed to uplift is numerically obtained for externally applied forces of a transient time variation. The soil medium is represented by an isotropic, homogeneous and linear half-space. The soil is treated by a time domain boundary element method, while the flexible foundation is treated by the finite element method. It was concluded that intermediate relative stiffness leads to moderate deformations when uplift is permitted. Very flexible footings produce higher deformations in unilateral contact compared to bilateral contact, and thus should be considered in their design. Unilateral contact does not significantly increase deformations for stiff footings subjected to concentrated central loading. However, relatively large deformation differences occur when the loading is eccentric, necessitating consideration of uplift in their design.

  3. Soil physicochemical properties and their significance for ...

    African Journals Online (AJOL)

    Soil physicochemical properties and their significance for sustainable sugarcane production in Kesem Allaideghe plains irrigation project area, Eastern Ethiopia. ... In order to improve soil structure and water availability, addition of gypsum, plant residues and organic matter are recommended. Keywords: Soil survey ...

  4. Climate Warming Can Increase Soil Carbon Fluxes Without Decreasing Soil Carbon Stocks in Boreal Forests

    Science.gov (United States)

    Ziegler, S. E.; Benner, R. H.; Billings, S. A.; Edwards, K. A.; Philben, M. J.; Zhu, X.; Laganiere, J.

    2016-12-01

    Ecosystem C fluxes respond positively to climate warming, however, the net impact of changing C fluxes on soil organic carbon (SOC) stocks over decadal scales remains unclear. Manipulative studies and global-scale observations have informed much of the existing knowledge of SOC responses to climate, providing insights on relatively short (e.g. days to years) and long (centuries to millennia) time scales, respectively. Natural climate gradient studies capture integrated ecosystem responses to climate on decadal time scales. Here we report the soil C reservoirs, fluxes into and out of those reservoirs, and the chemical composition of inputs and soil organic matter pools along a mesic boreal forest climate transect. The sites studied consist of similar forest composition, successional stage, and soil moisture but differ by 5.2°C mean annual temperature. Carbon fluxes through these boreal forest soils were greatest in the lowest latitude regions and indicate that enhanced C inputs can offset soil C losses with warming in these forests. Respiration rates increased by 55% and the flux of dissolved organic carbon from the organic to mineral soil horizons tripled across this climate gradient. The 2-fold increase in litterfall inputs to these soils coincided with a significant increase in the organic horizon C stock with warming, however, no significant difference in the surface mineral soil C stocks was observed. The younger mean age of the mineral soil C ( 70 versus 330 YBP) provided further evidence for the greater turnover of SOC in the warmer climate soils. In spite of these differences in mean radiocarbon age, mineral SOC exhibited chemical characteristics of highly decomposed material across all regions. In contrast with depth trends in soil OM diagenetic indices, diagenetic shifts with latitude were limited to increases in C:N and alkyl to O-alkyl ratios in the overlying organic horizons in the warmer relative to the colder regions. These data indicate that the

  5. Land use type significantly affects microbial gene transcription in soil.

    Science.gov (United States)

    Nacke, Heiko; Fischer, Christiane; Thürmer, Andrea; Meinicke, Peter; Daniel, Rolf

    2014-05-01

    Soil microorganisms play an essential role in sustaining biogeochemical processes and cycling of nutrients across different land use types. To gain insights into microbial gene transcription in forest and grassland soil, we isolated mRNA from 32 sampling sites. After sequencing of generated complementary DNA (cDNA), a total of 5,824,229 sequences could be further analyzed. We were able to assign nonribosomal cDNA sequences to all three domains of life. A dominance of bacterial sequences, which were affiliated to 25 different phyla, was found. Bacterial groups capable of aromatic compound degradation such as Phenylobacterium and Burkholderia were detected in significantly higher relative abundance in forest soil than in grassland soil. Accordingly, KEGG pathway categories related to degradation of aromatic ring-containing molecules (e.g., benzoate degradation) were identified in high abundance within forest soil-derived metatranscriptomic datasets. The impact of land use type forest on community composition and activity is evidently to a high degree caused by the presence of wood breakdown products. Correspondingly, bacterial groups known to be involved in lignin degradation and containing ligninolytic genes such as Burkholderia, Bradyrhizobium, and Azospirillum exhibited increased transcriptional activity in forest soil. Higher solar radiation in grassland presumably induced increased transcription of photosynthesis-related genes within this land use type. This is in accordance with high abundance of photosynthetic organisms and plant-infecting viruses in grassland.

  6. Melanised endophytic fungi may increase stores of organic carbon in soil

    Science.gov (United States)

    McGee, Peter; Mukasa Mugerwa, Tendo

    2013-04-01

    The processes underlying the carbon cycle in soil, especially sequestration of organic carbon (OC), are poorly understood. Hydrolysis and oxidation reduce organic matter. Hydrolysis degrades linear organic molecules in aerobic and anaerobic conditions, though it is slower in anaerobic conditions. Aromatic compounds are only degraded by oxidation. Oxygen is by far the most common electron acceptor in soil. Anaerobic conditions preclude oxidation in soil and will result in the preservation of aromatic compounds so long as the conditions remain anaerobic. We experimentally tested this model using melanised endophytic fungi. Melanin is a polyaromatic compound that can be readily visualised, though is difficult to quantify. An endophytic association provides the fungus with an ongoing source of energy. Fungal hyphae elongate considerable distances in soil where they may colonise aggregates, the core of which may be anaerobic. The hypothesis we tested is that melanised endophytic fungi increase OC in soil. Seedlings of subterranean clover inoculated with single isolates were grown in split pots where the impact of the fungus could be quantified in the hyphal chamber, separated from the roots by a steel mesh. We found that melanised endophytic fungi significantly increased OC and aromatic carbon in a well-aggregated carbon-rich soil. OC increased by up to 17% within 14 weeks. Twenty out of 24 isolates statistically significantly increased and none decreased OC. Increases differed between fungal isolates. Increases in the hyphal chamber were independent of any change in OC associated with the roots of the host plant. The storage of OC in field soils is being explored. Inoculation of plant roots with melanised endophytic fungi offers one means whereby OC may be increased in field soils.

  7. Evidence for the functional significance of diazotroph community structure in soil.

    Science.gov (United States)

    Hsu, Shi-Fang; Buckley, Daniel H

    2009-01-01

    Microbial ecologists continue to seek a greater understanding of the factors that govern the ecological significance of microbial community structure. Changes in community structure have been shown to have functional significance for processes that are mediated by a narrow spectrum of organisms, such as nitrification and denitrification, but in some cases, functional redundancy in the community seems to buffer microbial ecosystem processes. The functional significance of microbial community structure is frequently obscured by environmental variation and is hard to detect in short-term experiments. We examine the functional significance of free-living diazotrophs in a replicated long-term tillage experiment in which extraneous variation is minimized and N-fixation rates can be related to soil characteristics and diazotroph community structure. Soil characteristics were found to be primarily impacted by tillage management, whereas N-fixation rates and diazotroph community structure were impacted by both biomass management practices and interactions between tillage and biomass management. The data suggest that the variation in diazotroph community structure has a greater impact on N-fixation rates than do soil characteristics at the site. N-fixation rates displayed a saturating response to increases in diazotroph community diversity. These results show that the changes in the community structure of free-living diazotrophs in soils can have ecological significance and suggest that this response is related to a change in community diversity.

  8. Soil warming increases metabolic quotients of soil microorganisms without changes in temperature sensitivity of soil respiration

    Science.gov (United States)

    Marañón-Jiménez, Sara; Soong, Jenniffer L.; Leblans, Niki I. W.; Sigurdsson, Bjarni D.; Dauwe, Steven; Fransen, Erik; Janssens, Ivan A.

    2017-04-01

    Increasing temperatures can accelerate soil organic matter (SOM) decomposition and release large amounts of CO2 to the atmosphere, potentially inducing climate change feedbacks. Alterations to the temperature sensitivity and metabolic pathways of soil microorganisms in response to soil warming can play a key role in these soil carbon (C) losses. Here, we present results of an incubation experiment using soils from a geothermal gradient in Iceland that have been subjected to different intensities of soil warming (+0, +1, +3, +5, +10 and +20 °C above ambient) over seven years. We hypothesized that 7 years of soil warming would led to a depletion of labile organic substrates, with a subsequent decrease of the "apparent" temperature sensitivity of soil respiration. Associated to this C limitation and more sub-optimal conditions for microbial growth, we also hypothesized increased microbial metabolic quotients (soil respiration per unit of microbial biomass), which is associated with increases in the relative amount of C invested into catabolic pathways along the warming gradient. Soil respiration and basal respiration rates decreased with soil warming intensity, in parallel with a decline in soil C availability. Contrasting to our first hypothesis, we did not detect changes in the temperature sensitivity of soil respiration with soil warming or on the availability of nutrients and of labile C substrates at the time of incubation. However, in agreement to our second hypothesis, microbial metabolic quotients (soil respiration per unit of microbial biomass) increased at warmer temperatures, while the C retained in biomass decreased as substrate became limiting. Long-term (7 years) temperature increases thus triggered a change in the metabolic functioning of the soil microbial communities towards increasing energy costs for maintenance or resource acquisition, thereby lowering the capacity of C retention and stabilization of warmed soils. These results highlight the need

  9. Does soil compaction increase floods? A review

    Science.gov (United States)

    Alaoui, Abdallah; Rogger, Magdalena; Peth, Stephan; Blöschl, Günter

    2018-02-01

    Europe has experienced a series of major floods in the past years which suggests that flood magnitudes may have increased. Land degradation due to soil compaction from crop farming or grazing intensification is one of the potential drivers of this increase. A literature review suggests that most of the experimental evidence was generated at plot and hillslope scales. At larger scales, most studies are based on models. There are three ways in which soil compaction affects floods at the catchment scale: (i) through an increase in the area affected by soil compaction; (ii) by exacerbating the effects of changes in rainfall, especially for highly degraded soils; and (iii) when soil compaction coincides with soils characterized by a fine texture and a low infiltration capacity. We suggest that future research should focus on better synthesising past research on soil compaction and runoff, tailored field experiments to obtain a mechanistic understanding of the coupled mechanical and hydraulic processes, new mapping methods of soil compaction that combine mechanical and remote sensing approaches, and an effort to bridge all disciplines relevant to soil compaction effects on floods.

  10. Biochar amendment reduces paddy soil nitrogen leaching but increases net global warming potential in Ningxia irrigation, China.

    Science.gov (United States)

    Wang, Yongsheng; Liu, Yansui; Liu, Ruliang; Zhang, Aiping; Yang, Shiqi; Liu, Hongyuan; Zhou, Yang; Yang, Zhengli

    2017-05-09

    The efficacy of biochar as an environmentally friendly agent for non-point source and climate change mitigation remains uncertain. Our goal was to test the impact of biochar amendment on paddy rice nitrogen (N) uptake, soil N leaching, and soil CH 4 and N 2 O fluxes in northwest China. Biochar was applied at four rates (0, 4.5, 9 and13.5 t ha -1 yr -1 ). Biochar amendment significantly increased rice N uptake, soil total N concentration and the abundance of soil ammonia-oxidizing archaea (AOA), but it significantly reduced the soil NO 3 - -N concentration and soil bulk density. Biochar significantly reduced NO 3 - -N and NH 4 + -N leaching. The C2 and C3 treatments significantly increased the soil CH 4 flux and reduced the soil N 2 O flux, leading to significantly increased net global warming potential (GWP). Soil NO 3 - -N rather than NH 4 + -N was the key integrator of the soil CH 4 and N 2 O fluxes. Our results indicate that a shift in abundance of the AOA community and increased rice N uptake are closely linked to the reduced soil NO 3 - -N concentration under biochar amendment. Furthermore, soil NO 3 - -N availability plays an important role in regulating soil inorganic N leaching and net GWP in rice paddies in northwest China.

  11. Soil acidification increases metal extractability and bioavailability in old orchard soils of Northeast Jiaodong Peninsula in China

    International Nuclear Information System (INIS)

    Li, Lianzhen; Wu, Huifeng; Gestel, Cornelis A.M. van; Peijnenburg, Willie J.G.M.; Allen, Herbert E.

    2014-01-01

    The bioavailability of Cu, Zn, Pb and Cd from field-aged orchard soils in a certified fruit plantation area of the Northeast Jiaodong Peninsula in China was assessed using bioassays with earthworms (Eisenia fetida) and chemical assays. Soil acidity increased with increasing fruit cultivation periods with a lowest pH of 4.34. Metals were enriched in topsoils after decades of horticultural cultivation, with highest concentrations of Cu (132 kg −1 ) and Zn (168 mg kg −1 ) in old apple orchards and Pb (73 mg kg −1 ) and Cd (0.57 mg kg −1 ) in vineyard soil. Earthworm tissue concentrations of Cu and Pb significantly correlated with 0.01 M CaCl 2 -extractable soil concentrations (R 2  = 0.70, p < 0.001 for Cu; R 2  = 0.58, p < 0.01 for Pb). Because of the increased bioavailability, regular monitoring of soil conditions in old orchards and vineyards is recommended, and soil metal guidelines need reevaluation to afford appropriate environmental protection under acidifying conditions. - Highlights: • Soil acidity of Chinese orchards increased with increasing fruit cultivation period. • Metal levels were enriched in topsoils after decades of horticultural cultivation. • Earthworm bioassays and chemical assays were used to assess metal bioavailability. • Earthworm Cu and Pb concentrations correlated with CaCl 2 -extractable concentrations. • Regular monitoring of soil conditions in old orchards and vineyards is recommended. - Long-term cultivation leads to increased acidification and metal accumulation in horticultural soils, with higher metal bioavailability to earthworms

  12. Increased P diffusion as an explanation of increased P availability in flooded rice soils

    International Nuclear Information System (INIS)

    Turner, F.T.; Gilliam, J.W.

    1976-01-01

    Phosphorus supply factors (capacity, kinetic, intensity, and diffusivity) and plant growth were the approaches used to assess P supply of flooded rice soils. Increases in the capacity, intensity and kinetic factors, as measured by E-value, solution P concentration, and soil P release rate to a distilled water 'sink' respectively, were unpronounced and infrequent upon water-saturation of ten soils. However, increases in the diffusivity factor, as measured by 32 P diffusion coefficients, were at least ten-fold as soil moisture increased. The greatest increases in P diffusion occurred as soil moisture increased beyond one-third bar. Using a P-fertilized soil or P treated powdered cellulose as the P source and a minus P nutrient solution to nourish a split root system with water and nutrients, data were obtained which suggested that P uptake and rice shoot growth (indicators of P availability) increased with increasing moisture level. Phosphorus uptake and rice-shoot growth were greatest when the soil or P treated cellulose were water-saturated. These data indicate that increased soil P availability upon flooding can be attributed to an increase in the diffusivity factor

  13. Aerobic Bioremediation of PAH Contaminated Soil Results in Increased Genotoxicity and Developmental Toxicity.

    Science.gov (United States)

    Chibwe, Leah; Geier, Mitra C; Nakamura, Jun; Tanguay, Robert L; Aitken, Michael D; Simonich, Staci L Massey

    2015-12-01

    The formation of more polar and toxic polycyclic aromatic hydrocarbon (PAH) transformation products is one of the concerns associated with the bioremediation of PAH-contaminated soils. Soil contaminated with coal tar (prebioremediation) from a former manufactured gas plant (MGP) site was treated in a laboratory scale bioreactor (postbioremediation) and extracted using pressurized liquid extraction. The soil extracts were fractionated, based on polarity, and analyzed for 88 PAHs (unsubstituted, oxygenated, nitrated, and heterocyclic PAHs). The PAH concentrations in the soil tested, postbioremediation, were lower than their regulatory maximum allowable concentrations (MACs), with the exception of the higher molecular weight PAHs (BaA, BkF, BbF, BaP, and IcdP), most of which did not undergo significant biodegradation. The soil extract fractions were tested for genotoxicity using the DT40 chicken lymphocyte bioassay and developmental toxicity using the embryonic zebrafish (Danio rerio) bioassay. A statistically significant increase in genotoxicity was measured in the unfractionated soil extract, as well as in four polar soil extract fractions, postbioremediation (p toxicity was measured in one polar soil extract fraction, postbioremediation (p soil extract fractions in embryonic zebrafish, both pre- and postbioremediation. The increased toxicity measured postbioremediation is not likely due to the 88 PAHs measured in this study (including quinones), because most were not present in the toxic polar fractions and/or because their concentrations did not increase postbioremediation. However, the increased toxicity measured postbioremediation is likely due to hydroxylated and carboxylated transformation products of the 3- and 4-ring PAHs (PHE, 1MPHE, 2MPHE, PRY, BaA, and FLA) that were most degraded.

  14. Application of Serratia marcescens RZ-21 significantly enhances peanut yield and remediates continuously cropped peanut soil.

    Science.gov (United States)

    Ma, Hai-Yan; Yang, Bo; Wang, Hong-Wei; Yang, Qi-Yin; Dai, Chuan-Chao

    2016-01-15

    Continuous cropping practices cause a severe decline in peanut yield. The aim of this study was to investigate the remediation effect of Serratia marcescens on continuously cropped peanut soil. A pot experiment was conducted under natural conditions to determine peanut agronomic indices, soil microorganism characteristics, soil enzyme activities and antagonism ability to typical pathogens at different growth stages. Four treatments were applied to red soil as follows: an active fermentation liquor of S. marcescens (RZ-21), an equivalent sterilized fermentation liquor (M), an equivalent fermentation medium (P) and distilled water (CK). S. marcescens significantly inhibited the two typical plant pathogens Fusarium oxysporum A1 and Ralstonia solanacearum B1 and reduced their populations in rhizosphere soil. The RZ-21 treatment significantly increased peanut yield, vine dry weight, root nodules and taproot length by 62.3, 33, 72 and 61.4% respectively, followed by the M treatment. The P treatment also increased root nodules and root length slightly. RZ-21 also enhanced the activities of soil urease, sucrase and hydrogen peroxidase at various stages. In addition, RZ-21 and M treatments increased the average population of soil bacteria and decreased the average population of fungi in the three critical peanut growth stages, except for M in the case of the fungal population at flowering, thus balancing the structure of the soil microorganism community. This is the first report of S. marcescens being applied to continuously cropped peanut soil. The results suggest that S. marcescens RZ-21 has the potential to improve the soil environment and agricultural products and thus allow the development of sustainable management practices. © 2015 Society of Chemical Industry.

  15. Increasing Soil Organic Matter Enhances Inherent Soil Productivity while Offsetting Fertilization Effect under a Rice Cropping System

    Directory of Open Access Journals (Sweden)

    Ya-Nan Zhao

    2016-09-01

    Full Text Available Understanding the role of soil organic matter (SOM in soil quality and subsequent crop yield and input requirements is useful for agricultural sustainability. SOM is widely considered to affect a wide range of soil properties, however, great uncertainty still remains in identifying the relationships between SOM and crop yield due to the difficulty in separating the effect of SOM from other yield-limiting factors. Based on 543 on-farm experiments, where paired treatments with and without NPK fertilizer were conducted during 2005–2009, we quantified the inherent soil productivity, fertilization effect, and their contribution to rice yield and further evaluated their relationships with SOM contents under a rice cropping system in the Sichuan Basin of China. The inherent soil productivity assessed by rice grain yield under no fertilization (Y-CK was 5.8 t/ha, on average, and contributed 70% to the 8.3 t/ha of rice yield under NPK fertilization (Y-NPK while the other 30% was from the fertilization effect (FE. No significant correlation between SOM content and Y-NPK was observed, however, SOM content positively related to Y-CK and its contribution to Y-NPK but negatively to FE and its contribution to Y-NPK, indicating an increased soil contribution but a decreased fertilizer contribution to rice yield with increasing SOM. There were significantly positive relationships between SOM and soil available N, P, and K, indicating the potential contribution of SOM to inherent soil productivity by supplying nutrients from mineralization. As a result, approaches for SOM accumulation are practical to improve the inherent soil productivity and thereafter maintain a high crop productivity with less dependence on chemical fertilizers, while fertilization recommendations need to be adjusted with the temporal and spatial SOM variation.

  16. Is it real or apparent increased aggregate stability sometimes found in burned soils?

    Directory of Open Access Journals (Sweden)

    V. Arcenegui

    2013-05-01

    Full Text Available The increase in soil aggregate stability observed in many cases after burning is discussed in this paper. Soil samples under pine forest from two Mediterranean areas were collected for this experiment: acid soils from El Algibe Range (Los Alcornocales Natural Park, Cádiz, Southern Spain and calcareous soils of Sierra de la Grana (Alicante, Eastern Spain. In each case, soil aggregates (2 to 0.25 mm were selected and exposed to temperatures of 200, 250, 300, 500 and 700 oC during a 20-minutes period. In both cases weight loss after volatilization of substances and a significant destruction of aggregates with increasing temperature were observed. For acid soils, where organic matter is the main cementing agent, destruction of aggregates with temperature was more intense. Water repellency induced by combustion increased between 200 and 250 oC, also the remaining aggregates remaining increased within the initial size fraction after heating, increasing its stability. For temperatures above 300 oC, water repellency disappeared, although an increase in aggregate stability was observed, possibly due to changes in the mineral soil fraction. Therefore, it is concluded that burning may destroy part of the aggregates by combustion of organic matter, so selecting stable aggregates. Water repellency and transformations of soil minerals contribute to increased stability in selected aggregates.

  17. Engineering Significant of Swelling Soils

    OpenAIRE

    Behzad Kalantari

    2012-01-01

    This study describes some of the most important swelling characters of expansive soils when used as foundation materials to support various types of civil engineering structures. Expansive soils are considered among difficult foundation materials and expand upon wetting and shrink upon losing moisture. They are considered problematic soils for architectural and civil engineers. These types of soils may cause minor to major structural damages to pavements as well as buildings. It is therefore ...

  18. 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

  19. Elevated CO2 increases glomalin-related soil protein (GRSP) in the rhizosphere of Robinia pseudoacacia L. seedlings in Pb- and Cd-contaminated soils.

    Science.gov (United States)

    Jia, Xia; Zhao, Yonghua; Liu, Tuo; Huang, Shuping; Chang, Yafei

    2016-11-01

    Glomalin-related soil protein (GRSP), which contains glycoproteins produced by arbuscular mycorrhizal fungi (AMF), as well as non-mycorrhizal-related heat-stable proteins, lipids, and humic materials, is generally categorized into two fractions: easily extractable GRSP (EE-GRSP) and total GRSP (T-GRSP). GRSP plays an important role in soil carbon (C) sequestration and can stabilize heavy metals such as lead (Pb), cadmium (Cd), and manganese (Mn). Soil contamination by heavy metals is occurring in conjunction with rising atmospheric CO 2 in natural ecosystems due to human activities. However, the response of GRSP to elevated CO 2 combined with heavy metal contamination has not been widely reported. Here, we investigated the response of GRSP to elevated CO 2 in the rhizosphere of Robinia pseudoacacia L. seedlings in Pb- and Cd-contaminated soils. Elevated CO 2 (700 μmol mol -1 ) significantly increased T- and EE- GRSP concentrations in soils contaminated with Cd, Pb or Cd + Pb. GRSP contributed more carbon to the rhizosphere soil organic carbon pool under elevated CO 2  + heavy metals than under ambient CO 2 . The amount of Cd and Pb bound to GRSP was significantly higher under elevated (compared to ambient) CO 2 ; and elevated CO 2 increased the ratio of GRSP-bound Cd and Pb to total Cd and Pb. However, available Cd and Pb in rhizosphere soil under increased elevated CO 2 compared to ambient CO 2 . The combination of both metals and elevated CO 2 led to a significant increase in available Pb in rhizosphere soil compared to the Pb treatment alone. In conclusion, increased GRSP produced under elevated CO 2 could contribute to sequestration of soil pollutants by adsorption of Cd and Pb. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Coastal vegetation invasion increases greenhouse gas emission from wetland soils but also increases soil carbon accumulation

    International Nuclear Information System (INIS)

    Chen, Yaping; Chen, Guangcheng; Ye, Yong

    2015-01-01

    Soil properties and soil–atmosphere fluxes of CO 2 , CH 4 and N 2 O from four coastal wetlands were studied throughout the year, namely, native Kandelia obovata mangrove forest vs. exotic Sonneratia apetala mangrove forest, and native Cyperus malaccensis salt marsh vs. exotic Spartina alterniflora salt marsh. Soils of the four wetlands were all net sources of greenhouse gases while Sonneratia forest contributed the most with a total soil–atmosphere CO 2 -equivalent flux of 137.27 mg CO 2 m −2 h −1 , which is 69.23%, 99.75% and 44.56% higher than that of Kandelia, Cyperus and Spartina, respectively. The high underground biomass and distinctive root structure of Sonneratia might be responsible for its high greenhouse gas emission from the soil. Soils in Spartina marsh emitted the second largest amount of total greenhouse gases but it ranked first in emitting trace greenhouse gases. Annual average CH 4 and N 2 O fluxes from Spartina soil were 13.77 and 1.14 μmol m −2 h −1 , respectively, which are 2.08 and 1.46 times that of Kandelia, 1.03 and 1.15 times of Sonneratia, and 1.74 and 1.02 times of Cyperus, respectively. Spartina has longer growing season and higher productivity than native marshes which might increase greenhouse gas emission in cold seasons. Exotic wetland soils had higher carbon stock as compared to their respective native counterparts but their carbon stocks were offset by a larger proportion because of their higher greenhouse gas emissions. Annual total soil–atmosphere fluxes of greenhouse gases reduced soil carbon burial benefits by 8.1%, 9.5%, 6.4% and 7.2% for Kandelia, Sonneratia, Cyperus and Spartina, respectively, which narrowed down the gaps in net soil carbon stock between native and exotic wetlands. The results indicated that the invasion of exotic wetland plants might convert local coastal soils into a considerable atmospheric source of greenhouse gases although they at the same time increase soil carbon accumulation

  1. Coastal vegetation invasion increases greenhouse gas emission from wetland soils but also increases soil carbon accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yaping [Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, College of the Environment and Ecology, Xiamen University, Xiamen 361102, Fujian (China); Chen, Guangcheng [Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, Fujian (China); Ye, Yong, E-mail: yeyong.xmu@gmail.com [Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, College of the Environment and Ecology, Xiamen University, Xiamen 361102, Fujian (China)

    2015-09-01

    Soil properties and soil–atmosphere fluxes of CO{sub 2}, CH{sub 4} and N{sub 2}O from four coastal wetlands were studied throughout the year, namely, native Kandelia obovata mangrove forest vs. exotic Sonneratia apetala mangrove forest, and native Cyperus malaccensis salt marsh vs. exotic Spartina alterniflora salt marsh. Soils of the four wetlands were all net sources of greenhouse gases while Sonneratia forest contributed the most with a total soil–atmosphere CO{sub 2}-equivalent flux of 137.27 mg CO{sub 2} m{sup −2} h{sup −1}, which is 69.23%, 99.75% and 44.56% higher than that of Kandelia, Cyperus and Spartina, respectively. The high underground biomass and distinctive root structure of Sonneratia might be responsible for its high greenhouse gas emission from the soil. Soils in Spartina marsh emitted the second largest amount of total greenhouse gases but it ranked first in emitting trace greenhouse gases. Annual average CH{sub 4} and N{sub 2}O fluxes from Spartina soil were 13.77 and 1.14 μmol m{sup −2} h{sup −1}, respectively, which are 2.08 and 1.46 times that of Kandelia, 1.03 and 1.15 times of Sonneratia, and 1.74 and 1.02 times of Cyperus, respectively. Spartina has longer growing season and higher productivity than native marshes which might increase greenhouse gas emission in cold seasons. Exotic wetland soils had higher carbon stock as compared to their respective native counterparts but their carbon stocks were offset by a larger proportion because of their higher greenhouse gas emissions. Annual total soil–atmosphere fluxes of greenhouse gases reduced soil carbon burial benefits by 8.1%, 9.5%, 6.4% and 7.2% for Kandelia, Sonneratia, Cyperus and Spartina, respectively, which narrowed down the gaps in net soil carbon stock between native and exotic wetlands. The results indicated that the invasion of exotic wetland plants might convert local coastal soils into a considerable atmospheric source of greenhouse gases although they at the

  2. Aerobic Bioremediation of PAH Contaminated Soil Results in Increased Genotoxicity and Developmental Toxicity

    Science.gov (United States)

    Chibwe, Leah; Geier, Mitra C.; Nakamura, Jun; Tanguay, Robert L.; Aitken, Michael D.; Simonich, Staci L. Massey

    2015-01-01

    The formation of more polar and toxic polycyclic aromatic hydrocarbon (PAH) transformation products is one of the concerns associated with the bioremediation of PAH-contaminated soils. Soil contaminated with coal tar (pre-bioremediation) from a former manufactured gas plant (MGP) site was treated in a laboratory scale bioreactor (post-bioremediation) and extracted using pressurized liquid extraction. The soil extracts were fractionated, based on polarity, and analyzed for 88 PAHs (unsubstituted, oxygenated, nitrated, and heterocyclic PAHs). The PAH concentrations in the soil tested, post-bioremediation, were lower than their regulatory maximum allowable concentrations (MACs), with the exception of the higher molecular weight PAHs (BaA, BkF, BbF, BaP, and IcdP), most of which did not undergo significant biodegradation. The soil extract fractions were tested for genotoxicity using the DT40 chicken lymphocyte bioassay and developmental to xicity using the embryonic zebrafish (Danio rerio) bioassay. A statistically significant increase in genotoxicity was measured in the unfractionated soil extract, as well as in four polar soil extract fractions, post-bioremediation (p bioremediation (p bioremediation. The increased toxicity measured post-bioremediation is not likely due to the 88 PAHs measured in this study (including quinones), because most were not present in the toxic polar fractions and/or because their concentrations did not increase post-bioremediation. However, the increased toxicity measured post-bioremediation is likely due to hydroxylated and carboxylated transformation products of the 3- and 4-ring PAHs (PHE, 1MPHE, 2MPHE, PRY, BaA, and FLA) that were most degraded. PMID:26200254

  3. Does the increased air humidity affect soil respiration and carbon stocks?

    Science.gov (United States)

    Kukumägi, Mai; Celi, Luisella; Said-Pullicino, Daniel; Kupper, Priit; Sõber, Jaak; Lõhmus, Krista; Kutti, Sander; Ostonen, Ivika

    2013-04-01

    Climate manipulation experiments at ecosystem-scale enable us to simulate, investigate and predict changes in carbon balance of forest ecosystems. Considering the predicted increase in air humidity and precipitation for northern latitudes, this work aimed at investigating the effect of increased air humidity on soil respiration, distribution of soil organic matter (SOM) among pools having different turnover times, and microbial, fine root and rhizome biomass. The study was carried out in silver birch (Betula pendula Roth.) and hybrid aspen (Populus tremula L. × P. tremuloides Michx.) stands in a Free Air Humidity Manipulation (FAHM) experimental facility containing three humidified (H; on average 7% above current ambient levels since 2008) and three control (C) plots. Soil respiration rates were measured monthly during the growing season using a closed dynamic chamber method. Density fractionation was adopted to separate SOM into two light fractions (free and aggregate-occluded particulate organic matter, fPOM and oPOM respectively), and one heavy fraction (mineral-associated organic matter, MOM). The fine root and rhizome biomass and microbial data are presented for silver birch stands only. In 2011, after 4 growing seasons of humidity manipulation soil organic carbon contents were significantly higher in C plots than H plot (13.5 and 12.5 g C kg-1, respectively), while soil respiration tended to be higher in the latter. Microbial biomass and basal respiration were 13 and 14% higher in H plots than in the C plots, respectively. Twice more fine roots of trees were estimated in H plots, while the total fine root and rhizome biomass (tree + understory) was similar in C and H plots. Fine root turnover was higher for both silver birch and understory roots in H plots. Labile SOM light fractions (fPOM and oPOM) were significantly smaller in H plots with respect to C plots (silver birch and hybrid aspen stands together), whereas no differences were observed in the

  4. An increase in precipitation exacerbates negative effects of nitrogen deposition on soil cations and soil microbial communities in a temperate forest.

    Science.gov (United States)

    Shi, Leilei; Zhang, Hongzhi; Liu, Tao; Mao, Peng; Zhang, Weixin; Shao, Yuanhu; Fu, Shenglei

    2018-04-01

    World soils are subjected to a number of anthropogenic global change factors. Although many previous studies contributed to understand how single global change factors affect soil properties, there have been few studies aimed at understanding how two naturally co-occurring global change drivers, nitrogen (N) deposition and increased precipitation, affect critical soil properties. In addition, most atmospheric N deposition and precipitation increase studies have been simulated by directly adding N solution or water to the forest floor, and thus largely neglect some key canopy processes in natural conditions. These previous studies, therefore, may not realistically simulate natural atmospheric N deposition and precipitation increase in forest ecosystems. In a field experiment, we used novel canopy applications to investigate the effects of N deposition, increased precipitation, and their combination on soil chemical properties and the microbial community in a temperate deciduous forest. We found that both soil chemistry and microorganisms were sensitive to these global change factors, especially when they were simultaneously applied. These effects were evident within 2 years of treatment initiation. Canopy N deposition immediately accelerated soil acidification, base cation depletion, and toxic metal accumulation. Although increased precipitation only promoted base cation leaching, this exacerbated the effects of N deposition. Increased precipitation decreased soil fungal biomass, possible due to wetting/re-drying stress or to the depletion of Na. When N deposition and increased precipitation occurred together, soil gram-negative bacteria decreased significantly, and the community structure of soil bacteria was altered. The reduction of gram-negative bacterial biomass was closely linked to the accumulation of the toxic metals Al and Fe. These results suggested that short-term responses in soil cations following N deposition and increased precipitation could change

  5. Soil mulching significantly enhances yields and water and nitrogen use efficiencies of maize and wheat: a meta-analysis

    Science.gov (United States)

    Qin, Wei; Hu, Chunsheng; Oenema, Oene

    2015-11-01

    Global crop yields are limited by water and nutrient availability. Soil mulching (with plastic or straw) reduces evaporation, modifies soil temperature and thereby affects crop yields. Reported effects of mulching are sometimes contradictory, likely due to differences in climatic conditions, soil characteristics, crop species, and also water and nitrogen (N) input levels. Here we report on a meta-analysis of the effects of mulching on wheat and maize, using 1310 yield observations from 74 studies conducted in 19 countries. Our results indicate that mulching significantly increased yields, WUE (yield per unit water) and NUE (yield per unit N) by up to 60%, compared with no-mulching. Effects were larger for maize than wheat, and larger for plastic mulching than straw mulching. Interestingly, plastic mulching performed better at relatively low temperature while straw mulching showed the opposite trend. Effects of mulching also tended to decrease with increasing water input. Mulching effects were not related to soil organic matter content. In conclusion, soil mulching can significantly increase maize and wheat yields, WUE and NUE, and thereby may contribute to closing the yield gap between attainable and actual yields, especially in dryland and low nutrient input agriculture. The management of soil mulching requires site-specific knowledge.

  6. Soil mulching significantly enhances yields and water and nitrogen use efficiencies of maize and wheat: a meta-analysis.

    Science.gov (United States)

    Qin, Wei; Hu, Chunsheng; Oenema, Oene

    2015-11-20

    Global crop yields are limited by water and nutrient availability. Soil mulching (with plastic or straw) reduces evaporation, modifies soil temperature and thereby affects crop yields. Reported effects of mulching are sometimes contradictory, likely due to differences in climatic conditions, soil characteristics, crop species, and also water and nitrogen (N) input levels. Here we report on a meta-analysis of the effects of mulching on wheat and maize, using 1310 yield observations from 74 studies conducted in 19 countries. Our results indicate that mulching significantly increased yields, WUE (yield per unit water) and NUE (yield per unit N) by up to 60%, compared with no-mulching. Effects were larger for maize than wheat, and larger for plastic mulching than straw mulching. Interestingly, plastic mulching performed better at relatively low temperature while straw mulching showed the opposite trend. Effects of mulching also tended to decrease with increasing water input. Mulching effects were not related to soil organic matter content. In conclusion, soil mulching can significantly increase maize and wheat yields, WUE and NUE, and thereby may contribute to closing the yield gap between attainable and actual yields, especially in dryland and low nutrient input agriculture. The management of soil mulching requires site-specific knowledge.

  7. Microbial carbon pump and its significance for carbon sequestration in soils

    Science.gov (United States)

    Liang, Chao

    2017-04-01

    Studies of the decomposition, transformation and stabilization of soil organic carbon have dramatically increased in recent years due to growing interest in studying the global carbon cycle as it pertains to climate change. While it is readily accepted that the magnitude of the organic carbon reservoir in soils depends upon microbial involvement because soil carbon dynamics are ultimately the consequence of microbial growth and activity, it remains largely unknown how these microbe-mediated processes lead to soil carbon stabilization. Here, two pathways, ex vivo modification and in vivo turnover, were defined to jointly explain soil carbon dynamics driven by microbial catabolism and/or anabolism. Accordingly, a conceptual framework consisting of the raised concept of the soil "microbial carbon pump" (MCP) was demonstrated to describe how microbes act as an active player in soil carbon storage. The hypothesis is that the long-term microbial assimilation process may facilitate the formation of a set of organic compounds that are stabilized (whether via protection by physical interactions or a reduction in activation energy due to chemical composition), ultimately leading to the sequestration of microbial-derived carbon in soils. The need for increased efforts was proposed to seek to inspire new studies that utilize the soil MCP as a conceptual guideline for improving mechanistic understandings of the contributions of soil carbon dynamics to the responses of the terrestrial carbon cycle under global change.

  8. Long-term intensive management increased carbon occluded in phytolith (PhytOC) in bamboo forest soils

    Science.gov (United States)

    Huang, Zhang-Ting; Li, Yong-Fu; Jiang, Pei-Kun; Chang, Scott X.; Song, Zhao-Liang; Liu, Juan; Zhou, Guo-Mo

    2014-01-01

    Carbon (C) occluded in phytolith (PhytOC) is highly stable at millennium scale and its accumulation in soils can help increase long-term C sequestration. Here, we report that soil PhytOC storage significantly increased with increasing duration under intensive management (mulching and fertilization) in Lei bamboo (Phyllostachys praecox) plantations. The PhytOC storage in 0-40 cm soil layer in bamboo plantations increased by 217 Mg C ha-1, 20 years after being converted from paddy fields. The PhytOC accumulated at 79 kg C ha-1 yr-1, a rate far exceeding the global mean long-term soil C accumulation rate of 24 kg C ha-1 yr-1 reported in the literature. Approximately 86% of the increased PhytOC came from the large amount of mulch applied. Our data clearly demonstrate the decadal scale management effect on PhytOC accumulation, suggesting that heavy mulching is a potential method for increasing long-term organic C storage in soils for mitigating global climate change.

  9. Identification and paleoclimatic significance of magnetite nanoparticles in soils

    Science.gov (United States)

    Ahmed, Imad A. M.; Maher, Barbara A.

    2018-02-01

    In the world-famous sediments of the Chinese Loess Plateau, fossil soils alternate with windblown dust layers to record monsoonal variations over the last ˜3 My. The less-weathered, weakly magnetic dust layers reflect drier, colder glaciations. The fossil soils (paleosols) contain variable concentrations of nanoscale, strongly magnetic iron oxides, formed in situ during the wetter, warmer interglaciations. Mineralogical identification of the magnetic soil oxides is essential for deciphering these key paleoclimatic records. Formation of magnetite, a mixed Fe2+/Fe3+ ferrimagnet, has been linked to soil redox oscillations, and thence to paleorainfall. An opposite hypothesis states that magnetite can only form if the soil is water saturated for significant periods in order for Fe3+ to be reduced to Fe2+, and suggests instead the temperature-dependent formation of maghemite, an Fe3+-oxide, much of which ages subsequently into hematite, typically aluminum substituted. This latter, oxidizing pathway would have been temperature, but not rainfall dependent. Here, through structural fingerprinting and scanning transmission electron microscopy and electron energy loss spectroscopy analysis, we prove that magnetite is the dominant soil-formed ferrite. Maghemite is present in lower concentrations, and shows no evidence of aluminum substitution, negating its proposed precursor role for the aluminum-substituted hematite prevalent in the paleosols. Magnetite dominance demonstrates that magnetite formation occurs in well-drained, generally oxidizing soils, and that soil wetting/drying oscillations drive the degree of soil magnetic enhancement. The magnetic variations of the Chinese Loess Plateau paleosols thus record changes in monsoonal rainfall, over timescales of millions of years.

  10. Nitrogen deposition and management practices increase soil microbial biomass carbon but decrease diversity in Moso bamboo plantations

    Science.gov (United States)

    Li, Quan; Song, Xinzhang; Gu, Honghao; Gao, Fei

    2016-06-01

    Because microbial communities play a key role in carbon (C) and nitrogen (N) cycling, changes in the soil microbial community may directly affect ecosystem functioning. However, the effects of N deposition and management practices on soil microbes are still poorly understood. We studied the effects of these two factors on soil microbial biomass carbon (MBC) and community composition in Moso bamboo plantations using high-throughput sequencing of the 16S rRNA gene. Plantations under conventional (CM) or intensive management (IM) were subjected to one of four N treatments for 30 months. IM and N addition, both separately and in combination, significantly increased soil MBC while decreasing bacterial diversity. However, increases in soil MBC were inhibited when N addition exceeded 60 kg N•ha-1•yr-1. IM increased the relative abundances of Actinobacteria and Crenarchaeota but decreased that of Acidobacteria. N addition increased the relative abundances of Acidobacteria, Crenarchaeota, and Actinobacteria but decreased that of Proteobacteria. Soil bacterial diversity was significantly related to soil pH, C/N ratio, and nitrogen and available phosphorus content. Management practices exerted a greater influence over regulation of the soil MBC and microbial diversity compared to that of N deposition in Moso bamboo plantations.

  11. Fungi benefit from two decades of increased nutrient availability in tundra heath soil

    DEFF Research Database (Denmark)

    Rinnan, Riikka; Michelsen, Anders; Bååth, Erland

    2013-01-01

    is a predicted long-term consequence of climatic warming and mimicked by fertilization, both increase soil microbial biomass. However, while fertilization increased the relative abundance of fungi, warming caused only a minimal shift in the microbial community composition based on the phospholipid fatty acid......If microbial degradation of carbon substrates in arctic soil is stimulated by climatic warming, this would be a significant positive feedback on global change. With data from a climate change experiment in Northern Sweden we show that warming and enhanced soil nutrient availability, which...... (PLFA) and neutral lipid fatty acid (NLFA) profiles. The function of the microbial community was also differently affected, as indicated by stable isotope probing of PLFA and NLFA. We demonstrate that two decades of fertilization have favored fungi relative to bacteria, and increased the turnover...

  12. Biochar amendment decreases soil microbial biomass and increases bacterial diversity in Moso bamboo (Phyllostachys edulis) plantations under simulated nitrogen deposition

    Science.gov (United States)

    Li, Quan; Lei, Zhaofeng; Song, Xinzhang; Zhang, Zhiting; Ying, Yeqing; Peng, Changhui

    2018-04-01

    Biochar amendment has been proposed as a strategy to improve acidic soils after overuse of nitrogen fertilizers. However, little is known of the role of biochar in soil microbial biomass carbon (MBC) and bacterial community structure and diversity after soil acidification induced by nitrogen (N) deposition. Using high-throughput sequencing of the 16S rRNA gene, we determined the effects of biochar amendment (BC0, 0 t bamboo biochar ha‑1 BC20, 20 t bamboo biochar ha‑1 and BC40, 40 t bamboo biochar ha‑1) on the soil bacterial community structure and diversity in Moso bamboo plantations that had received simulated N deposition (N30, 30 kg N ha‑1 yr‑1 N60, 60 kg N ha‑1 yr‑1 N90, 90 kg N ha‑1 yr‑1 and N-free) for 21 months. After treatment of N-free plots, BC20 significantly increased soil MBC and bacterial diversity, while BC40 significantly decreased soil MBC but increased bacterial diversity. When used to amend N30 and N60 plots, biochar significantly decreased soil MBC and the reducing effect increased with biochar amendment amount. However, these significant effects were not observed in N90 plots. Under N deposition, biochar amendment largely increased soil bacterial diversity, and these effects depended on the rates of N deposition and biochar amendment. Soil bacterial diversity was significantly related to the soil C/N ratio, pH, and soil organic carbon content. These findings suggest an optimal approach for using biochar to offset the effects of N deposition in plantation soils and provide a new perspective for understanding the potential role of biochar amendments in plantation soil.

  13. Significance of mineralogy in soil mechanics

    Directory of Open Access Journals (Sweden)

    Bojana Dolinar

    2002-12-01

    Full Text Available The research of consistency limits according to Atterberg is of key importance in soil mechanics because it determines, in a simple way, results of interactions between solid and liquid phases in soils, and thus provides possibility to classify them in groups withsimilar mechanic properties. In most cases, the results of these investigations provide a good basis for predicting other properties such as deformability, expansion, hydraulic conductivity and strength of soils. This proves that basis factors influencing the valuesof consistency limits and other mechanic properties are the same. It is known that the values of consistency limits primarily depend on the type and quantity of clay minerals in soils. The article focuses on experimental evidence of dependence between the quantityof water at the liquid limit for soils and type, portion and specific surface of clay grains.Experiments were performed with monomineral soils, their mixtures and composed samples of clay- and non-clay components. It was established that in parallel orientation of clay particles the quantity of water between grains at liquid limit is dependent on their external specific surface.

  14. Long- term manure exposure increases soil bacterial community potential for plasmid uptake

    DEFF Research Database (Denmark)

    Musovic, Sanin; Klümper, Uli; Dechesne, Arnaud

    2014-01-01

    Microbial communities derived from soils subject to different agronomic treatments were challenged with three broad host range plasmids, RP4, pIPO2tet and pRO101, via solid surface filter matings to assess their permissiveness. Approximately 1 in 10 000 soil bacterial cells could receive and main......Microbial communities derived from soils subject to different agronomic treatments were challenged with three broad host range plasmids, RP4, pIPO2tet and pRO101, via solid surface filter matings to assess their permissiveness. Approximately 1 in 10 000 soil bacterial cells could receive...... and maintain the plasmids. The community permissiveness increased up to 100% in communities derived from manured soil. While the plasmid transfer frequency was significantly influenced by both the type of plasmid and the agronomic treatment, the diversity of the transconjugal pools was purely plasmid dependent...

  15. Soil Hydrological Attributes of an Integrated Crop-Livestock Agroecosystem: Increased Adaptation through Resistance to Soil Change

    International Nuclear Information System (INIS)

    Liebig, M.A; Tanaka, D.L; Kronberg, S.L; Karn, J.F; Scholljegerdes, E.J

    2011-01-01

    Integrated crop-livestock systems have been purported to have significant agronomic and environmental benefits compared to specialized, single-enterprise production systems. However, concerns exist regarding the effect of livestock in integrated systems to cause soil compaction, thereby decreasing infiltration of water into soil. Such concerns are compounded by projections of more frequent high-intensity rainfall events from anticipated climate change, which would act to increase surface runoff and soil erosion. A study was conducted to evaluate the effects of residue management, frequency of hoof traffic, season, and production system (e.g., integrated annual cropping versus perennial grass) on infiltration rates from 2001 through 2008 in central North Dakota, USA. Imposed treatments had no effect on infiltration rate at three, six, and nine years after study establishment, implying that agricultural producers should not be concerned with inhibited infiltration in integrated annual cropping systems, where winter grazing is used. The use of no-till management, coupled with annual freeze/thaw and wet/dry cycles, likely conferred an inherent resistance to change in near-surface soil properties affecting soil hydrological attributes. Accordingly, caution should be exercised in applying these results to other regions or management systems.

  16. Competition increases sensitivity of wheat (Triticum aestivum) to biotic plant-soil feedback.

    Science.gov (United States)

    Hol, W H Gera; de Boer, Wietse; ten Hooven, Freddy; van der Putten, Wim H

    2013-01-01

    Plant-soil feedback (PSF) and plant competition play an important role in structuring vegetation composition, but their interaction remains unclear. Recent studies suggest that competing plants could dilute pathogenic effects, whereas the standing view is that competition may increase the sensitivity of the focal plant to PSF. In agro-ecosystems each of these two options would yield contrasting outcomes: reduced versus enhanced effects of weeds on crop biomass production. To test the effect of competition on sensitivity to PSF, we grew Triticum aestivum (Common wheat) with and without competition from a weed community composed of Vicia villosa, Chenopodium album and Myosotis arvensis. Plants were grown in sterilized soil, with or without living field inoculum from 4 farms in the UK. In the conditioning phase, field inocula had both positive and negative effects on T. aestivum shoot biomass, depending on farm. In the feedback phase the differences between shoot biomass in T. aestivum monoculture on non-inoculated and inoculated soils had mostly disappeared. However, T. aestivum plants growing in mixtures in the feedback phase were larger on non-inoculated soil than on inoculated soil. Hence, T. aestivum was more sensitive to competition when the field soil biota was present. This was supported by the statistically significant negative correlation between shoot biomass of weeds and T. aestivum, which was absent on sterilized soil. In conclusion, competition in cereal crop-weed systems appears to increase cereal crop sensitivity to soil biota.

  17. Increased temperature and altered summer precipitation have differential effects on biological soil crusts in a dryland ecosystem

    Science.gov (United States)

    Johnson, Shannon L.; Kuske, Cheryl R.; Carney, Travis D.; Housman, David C.; Gallegos-Graves, La Verne; Belnap, Jayne

    2012-01-01

    Biological soil crusts (biocrusts) are common and ecologically important members of dryland ecosystems worldwide, where they stabilize soil surfaces and contribute newly fixed C and N to soils. To test the impacts of predicted climate change scenarios on biocrusts in a dryland ecosystem, the effects of a 2–3 °C increase in soil temperature and an increased frequency of smaller summer precipitation events were examined in a large, replicated field study conducted in the cold desert of the Colorado Plateau, USA. Surface soil biomass (DNA concentration), photosynthetically active cyanobacterial biomass (chlorophyll a concentration), cyanobacterial abundance (quantitative PCR assay), and bacterial community composition (16S rRNA gene sequencing) were monitored seasonally over 2 years. Soil microbial biomass and bacterial community composition were highly stratified between the 0–2 cm depth biocrusts and 5–10 cm depth soil beneath the biocrusts. The increase in temperature did not have a detectable effect on any of the measured parameters over 2 years. However, after the second summer of altered summer precipitation pattern, significant declines occurred in the surface soil biomass (avg. DNA concentration declined 38%), photosynthetic cyanobacterial biomass (avg. chlorophyll a concentration declined 78%), cyanobacterial abundance (avg. gene copies g−1 soil declined 95%), and proportion of Cyanobacteria in the biocrust bacterial community (avg. representation in sequence libraries declined 85%). Biocrusts are important contributors to soil stability, soil C and N stores, and plant performance, and the loss or reduction of biocrusts under an altered precipitation pattern associated with climate change could contribute significantly to lower soil fertility and increased erosion and dust production in dryland ecosystems at a regional scale.

  18. Nitrogen Cycling from Increased Soil Organic Carbon Contributes Both Positively and Negatively to Ecosystem Services in Wheat Agro-Ecosystems

    Directory of Open Access Journals (Sweden)

    Jeda Palmer

    2017-05-01

    Full Text Available Soil organic carbon (SOC is an important and manageable property of soils that impacts on multiple ecosystem services through its effect on soil processes such as nitrogen (N cycling and soil physical properties. There is considerable interest in increasing SOC concentration in agro-ecosystems worldwide. In some agro-ecosystems, increased SOC has been found to enhance the provision of ecosystem services such as the provision of food. However, increased SOC may increase the environmental footprint of some agro-ecosystems, for example by increasing nitrous oxide emissions. Given this uncertainty, progress is needed in quantifying the impact of increased SOC concentration on agro-ecosystems. Increased SOC concentration affects both N cycling and soil physical properties (i.e., water holding capacity. Thus, the aim of this study was to quantify the contribution, both positive and negative, of increased SOC concentration on ecosystem services provided by wheat agro-ecosystems. We used the Agricultural Production Systems sIMulator (APSIM to represent the effect of increased SOC concentration on N cycling and soil physical properties, and used model outputs as proxies for multiple ecosystem services from wheat production agro-ecosystems at seven locations around the world. Under increased SOC, we found that N cycling had a larger effect on a range of ecosystem services (food provision, filtering of N, and nitrous oxide regulation than soil physical properties. We predicted that food provision in these agro-ecosystems could be significantly increased by increased SOC concentration when N supply is limiting. Conversely, we predicted no significant benefit to food production from increasing SOC when soil N supply (from fertiliser and soil N stocks is not limiting. The effect of increasing SOC on N cycling also led to significantly higher nitrous oxide emissions, although the relative increase was small. We also found that N losses via deep drainage were

  19. Nitrogen Cycling from Increased Soil Organic Carbon Contributes Both Positively and Negatively to Ecosystem Services in Wheat Agro-Ecosystems.

    Science.gov (United States)

    Palmer, Jeda; Thorburn, Peter J; Biggs, Jody S; Dominati, Estelle J; Probert, Merv E; Meier, Elizabeth A; Huth, Neil I; Dodd, Mike; Snow, Val; Larsen, Joshua R; Parton, William J

    2017-01-01

    Soil organic carbon (SOC) is an important and manageable property of soils that impacts on multiple ecosystem services through its effect on soil processes such as nitrogen (N) cycling and soil physical properties. There is considerable interest in increasing SOC concentration in agro-ecosystems worldwide. In some agro-ecosystems, increased SOC has been found to enhance the provision of ecosystem services such as the provision of food. However, increased SOC may increase the environmental footprint of some agro-ecosystems, for example by increasing nitrous oxide emissions. Given this uncertainty, progress is needed in quantifying the impact of increased SOC concentration on agro-ecosystems. Increased SOC concentration affects both N cycling and soil physical properties (i.e., water holding capacity). Thus, the aim of this study was to quantify the contribution, both positive and negative, of increased SOC concentration on ecosystem services provided by wheat agro-ecosystems. We used the Agricultural Production Systems sIMulator (APSIM) to represent the effect of increased SOC concentration on N cycling and soil physical properties, and used model outputs as proxies for multiple ecosystem services from wheat production agro-ecosystems at seven locations around the world. Under increased SOC, we found that N cycling had a larger effect on a range of ecosystem services (food provision, filtering of N, and nitrous oxide regulation) than soil physical properties. We predicted that food provision in these agro-ecosystems could be significantly increased by increased SOC concentration when N supply is limiting. Conversely, we predicted no significant benefit to food production from increasing SOC when soil N supply (from fertiliser and soil N stocks) is not limiting. The effect of increasing SOC on N cycling also led to significantly higher nitrous oxide emissions, although the relative increase was small. We also found that N losses via deep drainage were minimally

  20. Different continuous cropping spans significantly affect microbial community membership and structure in a vanilla-grown soil as revealed by deep pyrosequencing.

    Science.gov (United States)

    Xiong, Wu; Zhao, Qingyun; Zhao, Jun; Xun, Weibing; Li, Rong; Zhang, Ruifu; Wu, Huasong; Shen, Qirong

    2015-07-01

    In the present study, soil bacterial and fungal communities across vanilla continuous cropping time-series fields were assessed through deep pyrosequencing of 16S ribosomal RNA (rRNA) genes and internal transcribed spacer (ITS) regions. The results demonstrated that the long-term monoculture of vanilla significantly altered soil microbial communities. Soil fungal diversity index increased with consecutive cropping years, whereas soil bacterial diversity was relatively stable. Bray-Curtis dissimilarity cluster and UniFrac-weighted principal coordinate analysis (PCoA) revealed that monoculture time was the major determinant for fungal community structure, but not for bacterial community structure. The relative abundances (RAs) of the Firmicutes, Actinobacteria, Bacteroidetes, and Basidiomycota phyla were depleted along the years of vanilla monoculture. Pearson correlations at the phyla level demonstrated that Actinobacteria, Armatimonadetes, Bacteroidetes, Verrucomicrobia, and Firmicutes had significant negative correlations with vanilla disease index (DI), while no significant correlation for fungal phyla was observed. In addition, the amount of the pathogen Fusarium oxysporum accumulated with increasing years and was significantly positively correlated with vanilla DI. By contrast, the abundance of beneficial bacteria, including Bradyrhizobium and Bacillus, significantly decreased over time. In sum, soil weakness and vanilla stem wilt disease after long-term continuous cropping can be attributed to the alteration of the soil microbial community membership and structure, i.e., the reduction of the beneficial microbes and the accumulation of the fungal pathogen.

  1. Carbon input increases microbial nitrogen demand, but not microbial nitrogen mining in boreal forest soils

    Science.gov (United States)

    Wild, Birgit; Alaei, Saeed; Bengtson, Per; Bodé, Samuel; Boeckx, Pascal; Schnecker, Jörg; Mayerhofer, Werner; Rütting, Tobias

    2016-04-01

    Plant primary production at mid and high latitudes is often limited by low soil N availability. It has been hypothesized that plants can indirectly increase soil N availability via root exudation, i.e., via the release of easily degradable organic compounds such as sugars into the soil. These compounds can stimulate microbial activity and extracellular enzyme synthesis, and thus promote soil organic matter (SOM) decomposition ("priming effect"). Even more, increased C availability in the rhizosphere might specifically stimulate the synthesis of enzymes targeting N-rich polymers such as proteins that store most of the soil N, but are too large for immediate uptake ("N mining"). This effect might be particularly important in boreal forests, where plants often maintain high primary production in spite of low soil N availability. We here tested the hypothesis that increased C availability promotes protein depolymerization, and thus soil N availability. In a laboratory incubation experiment, we added 13C-labeled glucose to a range of soil samples derived from boreal forests across Sweden, and monitored the release of CO2 by C mineralization, distinguishing between CO2 from the added glucose and from the native, unlabeled soil organic C (SOC). Using a set of 15N pool dilution assays, we further measured gross rates of protein depolymerization (the breakdown of proteins into amino acids) and N mineralization (the microbial release of excess N as ammonium). Comparing unamended control samples, we found a high variability in C and N mineralization rates, even when normalized by SOC content. Both C and N mineralization were significantly correlated to SOM C/N ratios, with high C mineralization at high C/N and high N mineralization at low C/N, suggesting that microorganisms adjusted C and N mineralization rates to the C/N ratio of their substrate and released C or N that was in excess. The addition of glucose significantly stimulated the mineralization of native SOC in soils

  2. Warming-related increases in soil CO2 efflux are explained by increased below-ground carbon flux

    Science.gov (United States)

    Christian P. Giardina; Creighton M. Litton; Susan E. Crow; Gregory P Asner

    2014-01-01

    The universally observed exponential increase in soil-surface CO2 effux (‘soil respiration’; FS) with increasing temperature has led to speculation that global warming will accelerate soil organic carbon (SOC) decomposition, reduce SOC storage, and drive a positive feedback to future warming. However, interpreting temperature–FS relationships,...

  3. Fungi benefit from two decades of increased nutrient availability in tundra heath soil.

    Science.gov (United States)

    Rinnan, Riikka; Michelsen, Anders; Bååth, Erland

    2013-01-01

    If microbial degradation of carbon substrates in arctic soil is stimulated by climatic warming, this would be a significant positive feedback on global change. With data from a climate change experiment in Northern Sweden we show that warming and enhanced soil nutrient availability, which is a predicted long-term consequence of climatic warming and mimicked by fertilization, both increase soil microbial biomass. However, while fertilization increased the relative abundance of fungi, warming caused only a minimal shift in the microbial community composition based on the phospholipid fatty acid (PLFA) and neutral lipid fatty acid (NLFA) profiles. The function of the microbial community was also differently affected, as indicated by stable isotope probing of PLFA and NLFA. We demonstrate that two decades of fertilization have favored fungi relative to bacteria, and increased the turnover of complex organic compounds such as vanillin, while warming has had no such effects. Furthermore, the NLFA-to-PLFA ratio for (13)C-incorporation from acetate increased in warmed plots but not in fertilized ones. Thus, fertilization cannot be used as a proxy for effects on warming in arctic tundra soils. Furthermore, the different functional responses suggest that the biomass increase found in both fertilized and warmed plots was mediated via different mechanisms.

  4. Dramatic Increases of Soil Microbial Functional Gene Diversity at the Treeline Ecotone of Changbai Mountain.

    Science.gov (United States)

    Shen, Congcong; Shi, Yu; Ni, Yingying; Deng, Ye; Van Nostrand, Joy D; He, Zhili; Zhou, Jizhong; Chu, Haiyan

    2016-01-01

    The elevational and latitudinal diversity patterns of microbial taxa have attracted great attention in the past decade. Recently, the distribution of functional attributes has been in the spotlight. Here, we report a study profiling soil microbial communities along an elevation gradient (500-2200 m) on Changbai Mountain. Using a comprehensive functional gene microarray (GeoChip 5.0), we found that microbial functional gene richness exhibited a dramatic increase at the treeline ecotone, but the bacterial taxonomic and phylogenetic diversity based on 16S rRNA gene sequencing did not exhibit such a similar trend. However, the β-diversity (compositional dissimilarity among sites) pattern for both bacterial taxa and functional genes was similar, showing significant elevational distance-decay patterns which presented increased dissimilarity with elevation. The bacterial taxonomic diversity/structure was strongly influenced by soil pH, while the functional gene diversity/structure was significantly correlated with soil dissolved organic carbon (DOC). This finding highlights that soil DOC may be a good predictor in determining the elevational distribution of microbial functional genes. The finding of significant shifts in functional gene diversity at the treeline ecotone could also provide valuable information for predicting the responses of microbial functions to climate change.

  5. Restoration using Azolla imbricata increases nitrogen functional bacterial groups and genes in soil.

    Science.gov (United States)

    Lu, Xiao-Ming; Lu, Peng-Zhen; Yang, Ke

    2017-05-01

    Microbial groups are major factors that influence soil function. Currently, there is a lack of studies on microbial functional groups. Although soil microorganisms play an important role in the nitrogen cycle, systematic studies of the effects of environmental factors on microbial populations in relation to key metabolic processes in the nitrogen cycle are seldom reported. In this study, we conducted a systematic analysis of the changes in nitrogen functional groups in mandarin orange garden soil treated with Azolla imbricata. The structures of the major functional bacterial groups and the functional gene abundances involved in key processes of the soil nitrogen cycle were analyzed using high-throughput sequencing (HTS) and quantitative real-time PCR, respectively. The results indicated that returning A. imbricata had an important influence on the composition of soil nitrogen functional bacterial communities. Treatment with A. imbricata increased the diversity of the nitrogen functional bacteria. The abundances of nitrogen functional genes were significantly higher in the treated soil compared with the control soil. Both the diversity of the major nitrogen functional bacteria (nifH bacteria, nirK bacteria, and narG bacteria) and the abundances of nitrogen functional genes in the soil showed significant positive correlations with the soil pH, the organic carbon content, available nitrogen, available phosphorus, and NH 4 + -N and NO 3 - -N contents. Treatment with 12.5 kg fresh A. imbricata per mandarin orange tree was effective to improve the quality of the mandarin orange garden soil. This study analyzed the mechanism of the changes in functional bacterial groups and genes involved in key metabolic processes of the nitrogen cycle in soil treated by A. imbricata.

  6. Greenhouse-gas emissions from soils increased by earthworms

    NARCIS (Netherlands)

    Lubbers, I.M.; Groenigen, van K.J.; Fonte, S.J.; Six, J.; Brussaard, L.; Groenigen, van J.W.

    2013-01-01

    Earthworms play an essential part in determining the greenhouse-gas balance of soils worldwide, and their influence is expected to grow over the next decades. They are thought to stimulate carbon sequestration in soil aggregates, but also to increase emissions of the main greenhouse gases carbon

  7. Effects of increased temperature and CO{sub 2} on soil quality

    Energy Technology Data Exchange (ETDEWEB)

    Ogner, G.

    1996-03-01

    This paper was read at the workshop ``The Norwegian Climate and Ozone Research Programme`` held on 11-12 March 1996. The Norwegian Forest Research Institute has studied the effects of increased CO{sub 2} and temperature on forest soil, soil leachate and plants in an open top chamber experiment. The purpose was to analyze the changes in soil parameters and the leaching of elements. Nitrate and aluminium received special attention. The growth of Norway spruce and birch was followed, and its impact on the soil parameters. Preliminary results indicate that the temperature increase of the soil and consequently an increased turnover of soil organic matter had the major effect on the quality of soil leachates. CO{sub 2} was less important. Leaching of NO{sub 3}{sup -} was high from control lysimeters with moss cover. Lysimeters with birch hardly leached NO{sub 3}{sup -} at all. Spruce is in an intermediate position. Increased leaching of Al{sup n+} is found for moss lysimeters. Leachates from birch lysimeters have high concentrations of Al{sup n+} only at the end of the growth seasons. Plant growth is to some extent increased by the CO{sub 2} treatment. Birch grew well in all lysimeters and all treatments, spruce developed clear symptoms of stress. This result does not fit with the increased availability of nutrients in soil solution

  8. Forest wildfire increases soil microbial biomass C:N:P stoichiometry in long-term effects

    Science.gov (United States)

    Zhou, Xuan

    2017-04-01

    Boreal forest fire strongly influences carbon (C) stock in permafrost soil by thawing permafrost table which accelerated microbe decomposition process. We studied soil microbial biomass stoichiometry in a gradient of four (3 yr, 25 yr, 46 yr and more than 100 yr) ages since fire in Canada boreal forest. Soil microbial biomass (MB) in long-term after fire is significantly higher than in short-term. MB C and nitrogen (N) were mainly dominated by corresponding soil element concentration and inorganic P, while MB phosphorus (P) changes were fully explained by soil N. Fire ages and soil temperature positively increased MB N and P, indicating the negative impact by fire. Microbial C:N:P gradually increased with fire ages from 15:2:1 to 76:6:1 and then drop down to 17:2:1 in the oldest fire ages. The degree of homeostasis of microbial C, N and P are close to 1 indicates non-homoeostasis within microbial elements, while it of C:N:P is close to 8 shows a strong homeostasis within element ratios and proved microbial stoichiometric ratio is not driven by soil element ratios. In conclusion, i) microbial biomass elements highly depends on soil nutrient supply rather than fire ages; ii) wildfire decreased microbial stoichiometry immediate after fire but increased with years after fire (YF) which at least 3 times higher than > 100 fire ages; iii) microbial biomass C, N and P deviated from strict homeostasis but C:N:P ratio reflects stronger homeostasis.

  9. Dramatic increases of soil microbial functional gene diversity at the treeline ecotone of Changbai Mountain

    Directory of Open Access Journals (Sweden)

    Congcong Shen

    2016-07-01

    Full Text Available The elevational and latitudinal diversity patterns of microbial taxa have attracted great attention in the past decade. Recently, the distribution of functional attributes has been in the spotlight. Here, we report a study profiling soil microbial communities along an elevation gradient (500 to 2200 m on Changbai Mountain. Using a comprehensive functional gene microarray (GeoChip 5.0, we found that microbial functional gene richness exhibited a dramatic increase at the treeline ecotone, but the bacterial taxonomic and phylogenetic diversity based on 16S rRNA gene sequencing did not exhibit such a similar trend. However, the β-diversity (compositional dissimilarity among sites for both bacterial taxa and functional genes was similar, showing significant elevational distance-decay patterns which presented increased dissimilarity with elevation. The bacterial taxonomic diversity/structure was strongly influenced by soil pH, while the functional gene diversity/structure was significantly correlated with soil dissolved organic carbon (DOC. This finding highlights that soil DOC may be a good predictor in determining the elevational distribution of microbial functional genes. The finding of significant shifts in functional gene diversity at the treeline ecotone could also provide valuable information for predicting the responses of microbial functions to climate change.

  10. Soil amendment with biochar increases the competitive ability of legumes via increased potassium availability

    NARCIS (Netherlands)

    Oram, N.J.; Van de Voorde, T.F.J.; Ouwehand, G.J.; Bezemer, T.M.; Mommer, Liesje; Jeffery, S.; van Groeningen, J.W.

    2014-01-01

    Soil amendment with biochar is currently proposed as a management strategy to improve soil quality and enhance plant productivity. Relatively little is known about how biochar affects plant competition, although it has been suggested that it can increase the competitive ability of legumes. This

  11. Improvements of soil quality for increased food production in Norway

    Science.gov (United States)

    Øygarden, Lillian; Klakegg, Ove; Børresen, Trond; Krogstad, Tore; Kjersti Uhlen, Anne

    2016-04-01

    Since the 1990ties, agricultural land in use in Norway has diminished and yields per hectare for cereals and forages have stagnated. An expert panel appointed to advice on how to increase Norwegian grain production emphasizes low profitability and poor soil quality as limiting factors. A White Paper from the Norwegian Government, Report No.9 (2011-2012), stated that the main goal for the agricultural sector is to increase food production proportional to the expected increase in population (20 % by 2030) in order to maintain self-sufficiency at the present level. This is the background for the interdisciplinary project AGROPRO "Agronomy for increased food production - Challenges and solutions" (2013 - 2017)" financed by the Norwegian research council. A mail goal is seeking possibilities for improvements in agronomic practices for increased and sustainable food production and to identify drivers and challenges for their implementation. Are the key to higher yields hidden in the soil? The paper present an overview of the research activities in the project and some results of the improvements of soil quality to minimize yield gap in cereal and forage production. Detailed new soil maps provide soil information on field scale of soil quality and the suitability for growing different crops like cereal production or vegetables. The detailed soil information is also beeing used for development and adaptation of the planning tool «Terranimo» to reduce risk of soil compaction.The farmer get available soil information for each field, provide information about the maschinery in use- tractors and equipment, tyres, pressure. The decision tool evaluate when the soil is suitable for tillage, calculate the risk of compaction for dry, moist and wet soil. New research data for compaction on Norwegian clay and silt soil are included. Climate change with wetter conditions gives challenges for growing cereals. The project is testing genetic variation in cereals for tolerance to water

  12. Excessive application of pig manure increases the risk of P loss in calcic cinnamon soil in China.

    Science.gov (United States)

    Yang, Yanju; Zhang, Haipeng; Qian, Xiaoqing; Duan, Jiannan; Wang, Gailan

    2017-12-31

    Soil phosphorus (P) is a critical factor affecting crop yields and water environmental quality. To investigate the degree of loss risk and forms of soil P in calcic cinnamon soil, the P fraction activities in soils were analysed using chemical methods, combined with an in situ field experiment. Seven treatments were set in this study, including control (unfertilized), no P fertilizer (No-P), mineral P fertilizer (Min-P), low (L-Man) and high (H-Man) quantities of pig manure, Min-P+L-Man, and Min-P+H-Man. The results showed that manure fertilizer could not only significantly increase maize yield but could also enhance the accumulation of soil P in organic and inorganic forms. After 23years of repeated fertilization, the soil Olsen-P contents respectively showed 64.7-, 43.7- and 31.9-fold increases in the Min-P+H-Man, Min-P+L-Man and H-Man treatments, while the soil Olsen-P in Min-P treatment only increased 23.7-fold. The soil Olsen-P thresholds ranged from 22.59 to 32.48mgkg -1 in calcic cinnamon soil to maintain a higher maize yield as well as a lower risk of P loss. Therefore, long-term excessive manure application could obviously raise the content of soil Olsen-P and increase the risk of P loss in calcic cinnamon soil. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Mapping Soil Properties of Africa at 250 m Resolution: Random Forests Significantly Improve Current Predictions.

    Directory of Open Access Journals (Sweden)

    Tomislav Hengl

    Full Text Available 80% of arable land in Africa has low soil fertility and suffers from physical soil problems. Additionally, significant amounts of nutrients are lost every year due to unsustainable soil management practices. This is partially the result of insufficient use of soil management knowledge. To help bridge the soil information gap in Africa, the Africa Soil Information Service (AfSIS project was established in 2008. Over the period 2008-2014, the AfSIS project compiled two point data sets: the Africa Soil Profiles (legacy database and the AfSIS Sentinel Site database. These data sets contain over 28 thousand sampling locations and represent the most comprehensive soil sample data sets of the African continent to date. Utilizing these point data sets in combination with a large number of covariates, we have generated a series of spatial predictions of soil properties relevant to the agricultural management--organic carbon, pH, sand, silt and clay fractions, bulk density, cation-exchange capacity, total nitrogen, exchangeable acidity, Al content and exchangeable bases (Ca, K, Mg, Na. We specifically investigate differences between two predictive approaches: random forests and linear regression. Results of 5-fold cross-validation demonstrate that the random forests algorithm consistently outperforms the linear regression algorithm, with average decreases of 15-75% in Root Mean Squared Error (RMSE across soil properties and depths. Fitting and running random forests models takes an order of magnitude more time and the modelling success is sensitive to artifacts in the input data, but as long as quality-controlled point data are provided, an increase in soil mapping accuracy can be expected. Results also indicate that globally predicted soil classes (USDA Soil Taxonomy, especially Alfisols and Mollisols help improve continental scale soil property mapping, and are among the most important predictors. This indicates a promising potential for transferring

  14. Boreal coniferous forest density leads to significant variations in soil physical and geochemical properties

    Science.gov (United States)

    Bastianelli, Carole; Ali, Adam A.; Beguin, Julien; Bergeron, Yves; Grondin, Pierre; Hély, Christelle; Paré, David

    2017-07-01

    At the northernmost extent of the managed forest in Quebec, Canada, the boreal forest is currently undergoing an ecological transition between two forest ecosystems. Open lichen woodlands (LW) are spreading southward at the expense of more productive closed-canopy black spruce-moss forests (MF). The objective of this study was to investigate whether soil properties could distinguish MF from LW in the transition zone where both ecosystem types coexist. This study brings out clear evidence that differences in vegetation cover can lead to significant variations in soil physical and geochemical properties.Here, we showed that soil carbon, exchangeable cations, and iron and aluminium crystallinity vary between boreal closed-canopy forests and open lichen woodlands, likely attributed to variations in soil microclimatic conditions. All the soils studied were typical podzolic soil profiles evolved from glacial till deposits that shared a similar texture of the C layer. However, soil humus and the B layer varied in thickness and chemistry between the two forest ecosystems at the pedon scale. Multivariate analyses of variance were used to evaluate how soil properties could help distinguish the two types at the site scale. MF humus (FH horizons horizons composing the O layer) showed significantly higher concentrations of organic carbon and nitrogen and of the main exchangeable base cations (Ca, Mg) than LW soils. The B horizon of LW sites held higher concentrations of total Al and Fe oxides and particularly greater concentrations of inorganic amorphous Fe oxides than MF mineral soils, while showing a thinner B layer. Overall, our results show that MF store three times more organic carbon in their soils (B+FH horizons, roots apart) than LW. We suggest that variations in soil properties between MF and LW are linked to a cascade of events involving the impacts of natural disturbances such as wildfires on forest regeneration that determines the vegetation structure (stand density

  15. Bio fertilization of Cereal and Legume Crops for Increasing Soil available P Uptake Using Nuclear Technique

    International Nuclear Information System (INIS)

    Soliman, S.; El-Gandour, E. A.; El Gala, A. M.; Ishac, Y. Z.

    2004-01-01

    Application of N and P in uncommon sources such as N 2 -fixers and AM fungi considered as an important source to save money and reduce pollution. In this concern, two pot experiments were carried out in sandy soils, to study the role of these neutral organisms in increasing the fertility of sandy soil. Wheat and faba bean were used. Seeds of wheat or faba bean were inoculated with Azotobacter or Rhizobium and planted in soils inoculated with and without AM fungi. A 20 mg P/kg soil in the form of single super phosphate (15.5 % P 2 O 5 ) or rock-P (26.6% P 2 O 5 ) were applied in the first experiment while KH 2 PO 4 was added in the second one. Dry weight, spore number, root infection, total and specific P were also determined. Maximum shoot growth were gained when either, wheat or faba bean inoculated with mycorrhizae and N2-fixers relative to the control. it was reached to 54 and 73%, respectively. Phosphorus uptake for shoots of both wheat and faba bean had been significantly increased upon inoculating with AM and/or Azotobacter or Rhizobium. Addition of fertilizer P help to identify the P uptake from soil or fertilizer. Mycorrhizal plants induced significant increase in Pdff by about 39 and 27% over inoculated with Azotobacter for wheat and Rhizobium for faba bean and it reached to 95 and 79% when inoculated with combined inoculation. This may be due to AM fungi absorb more available P than do nonmycorrhizal roots. FUE was increased from about 5 to 10% for wheat; 6 to 19% for faba bean. It can be concluded that, bio fertilizers can increase crop production and soil fertility. Rock-P might be recommended as a source of P fertilizer to be applied with AM fungi. (Authors)

  16. Microbial respiration per unit microbial biomass increases with carbon-to-nutrient ratios in soils

    Science.gov (United States)

    Spohn, Marie; Chodak, Marcin

    2015-04-01

    and the litter C:N ratio resulted from an increase in respiration with the C:N ratio in combination with no significant effect of the litter C:N ratio on the soil microbial biomass C concentration. The results suggest that soil microorganisms respire more C both in absolute terms and per unit microbial biomass C when decomposing N-poor substrate. Thus, the findings indicate that atmospheric N deposition, leading to decreased litter C:N ratios, might decrease microbial respiration in soils. Together, the two studies show that the respiration rate per unit microbial biomass C is not constant but increases with the soil carbon-to-nutrient ratio. References Spohn, M; Chodak, M (2015): Microbial respiration per unit biomass increases with carbon-to-nutrient ratios in forest soils, Soil Biology & Biochemistry 81, 128-133, doi:10.1016/j.soilbio.2014.11.008 Spohn, M (2014): Microbial respiration per unit microbial biomass depends on soil litter carbon-to-nitrogen ratio, Biogeosciences Discussions 11, 15037-15051, doi:10.5194/bgd-11-15037-2014

  17. Biochar increased water holding capacity but accelerated organic carbon leaching from a sloping farmland soil in China.

    Science.gov (United States)

    Liu, Chen; Wang, Honglan; Tang, Xiangyu; Guan, Zhuo; Reid, Brian J; Rajapaksha, Anushka Upamali; Ok, Yong Sik; Sun, Hui

    2016-01-01

    A hydrologically contained field study, to assess biochar (produced from mixed crop straws) influence upon soil hydraulic properties and dissolved organic carbon (DOC) leaching, was conducted on a loamy soil (entisol). The soil, noted for its low plant-available water and low soil organic matter, is the most important arable soil type in the upper reaches of the Yangtze River catchment, China. Pore size distribution characterization (by N2 adsorption, mercury intrusion, and water retention) showed that the biochar had a tri-modal pore size distribution. This included pores with diameters in the range of 0.1-10 μm that can retain plant-available water. Comparison of soil water retention curves between the control (0) and the biochar plots (16 t ha(-1) on dry weight basis) demonstrated biochar amendment to increase soil water holding capacity. However, significant increases in DOC concentration of soil pore water in both the plough layer and the undisturbed subsoil layer were observed in the biochar-amended plots. An increased loss of DOC relative to the control was observed upon rainfall events. Measurements of excitation-emission matrix (EEM) fluorescence indicated the DOC increment originated primarily from the organic carbon pool in the soil that became more soluble following biochar incorporation.

  18. Boreal coniferous forest density leads to significant variations in soil physical and geochemical properties

    Directory of Open Access Journals (Sweden)

    C. Bastianelli

    2017-07-01

    Full Text Available At the northernmost extent of the managed forest in Quebec, Canada, the boreal forest is currently undergoing an ecological transition between two forest ecosystems. Open lichen woodlands (LW are spreading southward at the expense of more productive closed-canopy black spruce–moss forests (MF. The objective of this study was to investigate whether soil properties could distinguish MF from LW in the transition zone where both ecosystem types coexist. This study brings out clear evidence that differences in vegetation cover can lead to significant variations in soil physical and geochemical properties.Here, we showed that soil carbon, exchangeable cations, and iron and aluminium crystallinity vary between boreal closed-canopy forests and open lichen woodlands, likely attributed to variations in soil microclimatic conditions. All the soils studied were typical podzolic soil profiles evolved from glacial till deposits that shared a similar texture of the C layer. However, soil humus and the B layer varied in thickness and chemistry between the two forest ecosystems at the pedon scale. Multivariate analyses of variance were used to evaluate how soil properties could help distinguish the two types at the site scale. MF humus (FH horizons horizons composing the O layer showed significantly higher concentrations of organic carbon and nitrogen and of the main exchangeable base cations (Ca, Mg than LW soils. The B horizon of LW sites held higher concentrations of total Al and Fe oxides and particularly greater concentrations of inorganic amorphous Fe oxides than MF mineral soils, while showing a thinner B layer. Overall, our results show that MF store three times more organic carbon in their soils (B+FH horizons, roots apart than LW. We suggest that variations in soil properties between MF and LW are linked to a cascade of events involving the impacts of natural disturbances such as wildfires on forest regeneration that determines the vegetation

  19. 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

  20. 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.

  1. [Effect of trampling disturbance on soil infiltration of biological soil crusts].

    Science.gov (United States)

    Shi, Ya Fang; Zhao, Yun Ge; Li, Chen Hui; Wang, Shan Shan; Yang, Qiao Yun; Xie, Shen Qi

    2017-10-01

    The effect of trampling disturbance on soil infiltration of biological soil crusts was investigated by using simulated rainfall. The results showed that the trampling disturbance significantly increased soil surface roughness. The increasing extent depended on the disturbance intensity. Soil surface roughness values at 50% disturbance increased by 91% compared with the undisturbed treatment. The runoff was delayed by trampling disturbance. A linear increase in the time of runoff yield was observed along with the increasing disturbance intensity within 20%-50%. The time of runoff yield at 50% disturbance increased by 169.7% compared with the undisturbed treatment. Trampling disturbance increased soil infiltration and consequently decreased the runoff coefficient. The cumulative infiltration amount at 50% disturbance increased by 12.6% compared with the undisturbed treatment. Soil infiltration significant decreased when biocrusts were removed. The cumulative infiltration of the treatment of biocrusts removal decreased by 30.2% compared with the undisturbed treatment. Trampling disturbance did not significantly increase the soil loss when the distur bance intensity was lower than 50%, while the biocrusts removal resulted in 10 times higher in soil erosion modulus. The trampling disturbance of lower than 50% on biocrusts might improve soil infiltration and reduce the risk of runoff, thus might improve the soil moisture without obviously increa sing the soil loss.

  2. Tolerance of soil flagellates to increased NaCl levels

    DEFF Research Database (Denmark)

    Ekelund, Flemming

    2002-01-01

    The ability of heterotrophic flagellates to survive and adapt to increasing salinities was investigated in this study. Whole soil samples were subjected to salinities corresponding to marine conditions and clonal cultures were used to perform growth and adaptation experiments at a wide range...... of different salinities (0-50 ppm). More morphotypes tolerant to elevated NaCl levels were found in road verge soil that was heavily exposed to de-icing salt than in less exposed soils, though there were fewer tolerant than intolerant morphotypes in all soils examined. Heterotrophic flagellates isolated...... on a freshwater medium from a non-exposed soil were unable to thrive at salinities above 15 ppt, and showed reduced growth rates even at low salt salinities (1-5 ppt). The findings suggest that heterotrophic soil flagellates are less tolerant to NaCl than their aquatic relatives, possibly due to their long...

  3. Reduction of exchangeable calcium and magnesium in soil with increasing pH

    Directory of Open Access Journals (Sweden)

    Miyazawa Mário

    2001-01-01

    Full Text Available A laboratory study was conducted with soil samples and synthetic solutions to investigate possible mechanisms related with reduction in KCl exchangeable Ca and Mg with increasing pH. Increasing soil pH over 5.3 with CaCO3 added to the soil and with NaOH solution added to soil/KCl suspension increased adsorptions of Ca and Mg. The reduction of Mg was greater than Ca and was related to the concentration of soil exchangeable Al. The decreases of soluble Ca and Mg following addition of Al in synthetic solution were at pH > 7.5. The isomorphic coprecipitation reaction with Al compounds may be the most possible mechanism responsible for the decrease of exchangeable Ca and Mg with increasing pH. Possible chemical reactions are presented.

  4. Soil acidification increases metal extractability and bioavailability in old orchard soils of Northeast Jiaodong Peninsula in China

    NARCIS (Netherlands)

    Li, Lianzhen; Wu, Huifeng; van Gestel, C.A.M.; Peijnenburg, W.J.G.M.; Allen, Herbert E.

    2014-01-01

    The bioavailability of Cu, Zn, Pb and Cd from field-aged orchard soils in a certified fruit plantation area of the Northeast Jiaodong Peninsula in China was assessed using bioassays with earthworms (Eisenia fetida) and chemical assays. Soil acidity increased with increasing fruit cultivation periods

  5. Green manure addition to soil increases grain zinc concentration in bread wheat.

    Directory of Open Access Journals (Sweden)

    Forough Aghili

    Full Text Available Zinc (Zn deficiency is a major problem for many people living on wheat-based diets. Here, we explored whether addition of green manure of red clover and sunflower to a calcareous soil or inoculating a non-indigenous arbuscular mycorrhizal fungal (AMF strain may increase grain Zn concentration in bread wheat. For this purpose we performed a multifactorial pot experiment, in which the effects of two green manures (red clover, sunflower, ZnSO4 application, soil γ-irradiation (elimination of naturally occurring AMF, and AMF inoculation were tested. Both green manures were labeled with 65Zn radiotracer to record the Zn recoveries in the aboveground plant biomass. Application of ZnSO4 fertilizer increased grain Zn concentration from 20 to 39 mg Zn kg-1 and sole addition of green manure of sunflower to soil raised grain Zn concentration to 31 mg Zn kg-1. Adding the two together to soil increased grain Zn concentration even further to 54 mg Zn kg-1. Mixing green manure of sunflower to soil mobilized additional 48 µg Zn (kg soil-1 for transfer to the aboveground plant biomass, compared to the total of 132 µg Zn (kg soil-1 taken up from plain soil when neither green manure nor ZnSO4 were applied. Green manure amendments to soil also raised the DTPA-extractable Zn in soil. Inoculating a non-indigenous AMF did not increase plant Zn uptake. The study thus showed that organic matter amendments to soil can contribute to a better utilization of naturally stocked soil micronutrients, and thereby reduce any need for major external inputs.

  6. Increasing temperature reduces the coupling between available nitrogen and phosphorus in soils of Chinese grasslands

    Science.gov (United States)

    Geng, Yan; Baumann, Frank; Song, Chao; Zhang, Mi; Shi, Yue; Kühn, Peter; Scholten, Thomas; He, Jin-Sheng

    2017-03-01

    Changes in climatic conditions along geographical gradients greatly affect soil nutrient cycling processes. Yet how climate regimes such as changes in temperature influence soil nitrogen (N) and phosphorus (P) concentrations and their stoichiometry is not well understood. This study investigated the spatial pattern and variability of soil N and P availability as well as their coupling relationships at two soil layers (0-10 and 10-20 cm) along a 4000-km climate transect in two grassland biomes of China, the Inner Mongolian temperate grasslands and the Tibetan alpine grasslands. Our results found that in both grasslands, from cold to warm sites the amounts of soil total N, total P and available P all decreased. By contrast, the amount of available N was positively related to mean annual temperature in the Tibetan grasslands. Meanwhile, with increasing temperature ratio of available N to P significantly increased but the linear relationship between them was considerably reduced. Thus, increasing temperature may not only induce a stoichiometric shift but also loose the coupling between available N and P. This N-P decoupling under warmer conditions was more evident in the Tibetan alpine grasslands where P limitation might become more widespread relative to N as temperatures continue to rise.

  7. Long-term field application of sewage sludge increases the abundance of antibiotic resistance genes in soil.

    Science.gov (United States)

    Chen, Qinglin; An, Xinli; Li, Hu; Su, Jianqiang; Ma, Yibing; Zhu, Yong-Guan

    2016-01-01

    Sewage sludge and manure are common soil amendments in crop production; however, their impact on the abundance and diversity of the antibiotic resistome in soil remains elusive. In this study, by using high-throughput sequencing and high-throughput quantitative PCR, the patterns of bacterial community and antibiotic resistance genes (ARGs) in a long-term field experiment were investigated to gain insights into these impacts. A total of 130 unique ARGs and 5 mobile genetic elements (MGEs) were detected and the long-term application of sewage sludge and chicken manure significantly increased the abundance and diversity of ARGs in the soil. Genes conferring resistance to beta-lactams, tetracyclines, and multiple drugs were dominant in the samples. Sewage sludge or chicken manure applications caused significant enrichment of 108 unique ARGs and MGEs with a maximum enrichment of up to 3845 folds for mexF. The enrichment of MGEs suggested that the application of sewage sludge or manure may accelerate the dissemination of ARGs in soil through horizontal gene transfer (HGT). Based on the co-occurrence pattern of ARGs subtypes revealed by network analysis, aacC, oprD and mphA-02, were proposed to be potential indicators for quantitative estimation of the co-occurring ARGs subtypes abundance by power functions. The application of sewage sludge and manure resulted in significant increase of bacterial diversity in soil, Proteobacteria, Acidobacteria, Actinobacteria and Chloroflexi were the dominant phyla (>10% in each sample). Five bacterial phyla (Chloroflexi, Planctomycetes, Firmicutes, Gemmatimonadetes and Bacteroidetes) were found to be significantly correlated with the ARGs in soil. Mantel test and variation partitioning analysis (VPA) suggested that bacterial community shifts, rather than MGEs, is the major driver shaping the antibiotic resistome. Additionally, the co-occurrence pattern between ARGs and microbial taxa revealed by network analysis indicated that four

  8. Organic fertilizer application increases the soil respiration and net ecosystem carbon dioxide absorption of paddy fields under water-saving irrigation.

    Science.gov (United States)

    Yang, Shihong; Xiao, Ya Nan; Xu, Junzeng

    2018-04-01

    Quantifying carbon sequestration in paddy soil is necessary to understand the effect of agricultural practices on carbon cycles. The objective of this study was to assess the effect of organic fertilizer addition (MF) on the soil respiration and net ecosystem carbon dioxide (CO 2 ) absorption of paddy fields under water-saving irrigation (CI) in the Taihu Lake Region of China during the 2014 and 2015 rice-growing seasons. Compared with the traditional fertilizer and water management (FC), the joint regulation of CI and MF (CM) significantly increased the rice yields and irrigation water use efficiencies of paddy fields by 4.02~5.08 and 83.54~109.97% (p < 0.05). The effects of organic fertilizer addition on soil respiration and net ecosystem CO 2 absorption rates showed inter-annual differences. CM paddy fields showed a higher soil respiration and net CO 2 absorption rates during some periods of the rice growth stage in the first year and during most periods of the rice growth stage in the second year. These fields also had significantly higher total CO 2 emission through soil respiration (total R soil ) and total net CO 2 absorption compared with FC paddy fields (p < 0.05). The total R soil and net ecosystem CO 2 absorption of CM paddy fields were 67.39~91.55 and 129.41~113.75 mol m -2 , which were 27.66~135.52 and 12.96~31.66% higher than those of FC paddy fields. The interaction between water and fertilizer management had significant effects on total net ecosystem CO 2 absorption. The frequent alternate wet-dry cycles of CI paddy fields increased the soil respiration and reduced the net CO 2 absorption. Organic fertilizer promoted the soil respiration of paddy soil but also increased its net CO 2 absorption and organic carbon content. Therefore, the joint regulation of water-saving irrigation and organic fertilizer is an effective measure for maintaining yield, increasing irrigation water use efficiency, mitigating CO 2 emission, and promoting paddy

  9. Time series modelling of increased soil temperature anomalies during long period

    Science.gov (United States)

    Shirvani, Amin; Moradi, Farzad; Moosavi, Ali Akbar

    2015-10-01

    Soil temperature just beneath the soil surface is highly dynamic and has a direct impact on plant seed germination and is probably the most distinct and recognisable factor governing emergence. Autoregressive integrated moving average as a stochastic model was developed to predict the weekly soil temperature anomalies at 10 cm depth, one of the most important soil parameters. The weekly soil temperature anomalies for the periods of January1986-December 2011 and January 2012-December 2013 were taken into consideration to construct and test autoregressive integrated moving average models. The proposed model autoregressive integrated moving average (2,1,1) had a minimum value of Akaike information criterion and its estimated coefficients were different from zero at 5% significance level. The prediction of the weekly soil temperature anomalies during the test period using this proposed model indicated a high correlation coefficient between the observed and predicted data - that was 0.99 for lead time 1 week. Linear trend analysis indicated that the soil temperature anomalies warmed up significantly by 1.8°C during the period of 1986-2011.

  10. Faster turnover of new soil carbon inputs under increased atmospheric CO2.

    Science.gov (United States)

    van Groenigen, Kees Jan; Osenberg, Craig W; Terrer, César; Carrillo, Yolima; Dijkstra, Feike A; Heath, James; Nie, Ming; Pendall, Elise; Phillips, Richard P; Hungate, Bruce A

    2017-10-01

    Rising levels of atmospheric CO 2 frequently stimulate plant inputs to soil, but the consequences of these changes for soil carbon (C) dynamics are poorly understood. Plant-derived inputs can accumulate in the soil and become part of the soil C pool ("new soil C"), or accelerate losses of pre-existing ("old") soil C. The dynamics of the new and old pools will likely differ and alter the long-term fate of soil C, but these separate pools, which can be distinguished through isotopic labeling, have not been considered in past syntheses. Using meta-analysis, we found that while elevated CO 2 (ranging from 550 to 800 parts per million by volume) stimulates the accumulation of new soil C in the short term (soil C pool over either temporal scale. Our results are inconsistent with predictions of conventional soil C models and suggest that elevated CO 2 might increase turnover rates of new soil C. Because increased turnover rates of new soil C limit the potential for additional soil C sequestration, the capacity of land ecosystems to slow the rise in atmospheric CO 2 concentrations may be smaller than previously assumed. © 2017 John Wiley & Sons Ltd.

  11. Application of nanoparticle of rock phosphate and biofertilizer in increasing some soil chemical characteristics of variable charge soil

    Science.gov (United States)

    Devnita, Rina; Joy, Benny; Arifin, Mahfud; Hudaya, Ridha; Oktaviani, Nurul

    2018-02-01

    Soils in Indonesia are dominated by variable charge soils where the technology like fertilization did not give the same result as the soils with permanent charge. The objectives of this research is to increase some chemical characteristic of variable charge soils by using the high negative charge ameliorations like rock phosphate in nanoparticle combined with biofertilizer. The research used a complete randomized experimental design in factorial with two factors. The first factor was nanoparticle of rock phosphate consists of four doses on soil weight percentage (0%, 2.5%, 5.0% and 7.5%). The second factor was biofertilizer consisted of two doses (without biofertilizer and 1 g.kg-1 soil biofertilizer). The combination treatments replicated three times. Variable charge soil used was Andisol. Andisol and the treatments were incubated for 4 months. Soil samples were taken after one and four months during incubation period to be analyzed for P-retention, available P and potential P. The result showed that all combinations of rock phosphate and biofertilizer decreased the P-retention to 75-77% after one month. Independently, application of 7.5% of rock phosphate decreased P-retention to 87.22% after four months, increased available P (245.37 and 19.12 mg.kg-1) and potential P (1354.78 and 3000.99 mg/100) after one and four months. Independently, biofertilizer increased the P-retention to 91.66% after four months, decreased available P to 121.55 mg.kg-1 after one month but increased to 12.55 mg.kg-1 after four months, decreased potential P to 635.30 after one month but increased to 1810.40 mg.100 g-1 after four months.

  12. Uptake and utilization of soil and fertilizer phosphorus by wheat in medium black soils

    International Nuclear Information System (INIS)

    Mahajan, J.P.

    1980-01-01

    A field experiment was conducted using labelled superphosphate to study the uptake and utilization of soil and fertilizer phosphorus by wheat under different soil fertility gradients and phosphorus levels. Grain, straw and total dry matter yield and total P uptake in wheat increased significantly with increasing soil fertility status and P levels (P 0 to P 90 kg P 2 O 5 /ha). Percent P derived from fertilizer increased significantly with increase in P levels but decreased with increasing fertility status of soil. Similar trend was observed in fertilizer P uptake in grain, straw and total dry matter, however, percent utilization of applied P decreased significantly with increasing P levels and fertility status of soil. Soil P uptake increased with increasing fertility status of soil. (author)

  13. Charcoal Increases Microbial Activity in Eastern Sierra Nevada Forest Soils

    Directory of Open Access Journals (Sweden)

    Zachary W. Carter

    2018-02-01

    Full Text Available Fire is an important component of forests in the western United States. Not only are forests subjected to wildfires, but fire is also an important management tool to reduce fuels loads. Charcoal, a product of fire, can have major impacts on carbon (C and nitrogen (N cycling in forest soils, but it is unclear how these effects vary by dominant vegetation. In this study, soils collected from Jeffrey pine (JP or lodgepole pine (LP dominated areas and amended with charcoal derived from JP or LP were incubated to assess the importance of charcoal on microbial respiration and potential nitrification. In addition, polyphenol sorption was measured in unamended and charcoal-amended soils. In general, microbial respiration was highest at the 1% and 2.5% charcoal additions, but charcoal amendment had limited effects on potential nitrification rates throughout the incubation. Microbial respiration rates decreased but potential nitrification rates increased over time across most treatments. Increased microbial respiration may have been caused by priming of native organic matter rather than the decomposition of charcoal itself. Charcoal had a larger stimulatory effect on microbial respiration in LP soils than JP soils. Charcoal type had little effect on microbial processes, but polyphenol sorption was higher on LP-derived than JP-derived charcoal at higher amendment levels despite surface area being similar for both charcoal types. The results from our study suggest that the presence of charcoal can increase microbial activity in soils, but the exact mechanisms are still unclear.

  14. Limited carbon storage in soil and litter of experimental forest plots under increased atmospheric CO2

    International Nuclear Information System (INIS)

    Schlesinger, W.H.; Lichter, J.

    2001-01-01

    The current rise in atmospheric CO 2 concentration is thought to be mitigated in part by carbon sequestration within forest ecosystems, where carbon can be stored in vegetation or soils. The storage of carbon in soils is determined by the fraction that is sequestered in persistent organic materials, such as humus. In experimental forest plots of loblolly pine (Pinus taeda) exposed to high CO 2 concentrations, nearly half of the carbon uptake is allocated to short-lived tissues, largely foliage. These tissues fall to the ground and decompose, normally contributing only a small portion of their carbon content to refractory soil humic materials. Such findings call into question the role of soils as long-term carbon sinks, and show the need for a better understanding of carbon cycling in forest soils. Here we report a significant accumulation of carbon in the litter layer of experimental forest plots after three years of growth at increased CO 2 concentrations (565 μ l 1 ). But fast turnover times of organic carbon in the litter layer (of about three years) appear to constrain the potential size of this carbon sink. Given the observation that carbon accumulation in the deeper mineral soil layers was absent, we suggest that significant, long-term net carbon sequestration in forest soils is unlikely. (author)

  15. Why does carbon increase in highly weathered soil under no-till upon lime and gypsum use?

    Science.gov (United States)

    Inagaki, Thiago Massao; de Moraes Sá, João Carlos; Caires, Eduardo Fávero; Gonçalves, Daniel Ruiz Potma

    2017-12-01

    Field experiments have been used to explain how soil organic carbon (SOC) dynamics is affected by lime and gypsum applications, however, how SOC storage occurs is still debatable. We hypothesized that although many studies conclude that Ca-based soil amendments such as lime and gypsum may lead to SOC depletion due to the enhancement of microbial activity, the same does not occur under conservation agriculture conditions. Thus, the objective of this study was to elucidate the effects of lime and gypsum applications on soil microbial activity and SOC stocks in a no-till field and in a laboratory incubation study simulating no-till conditions. The field experiment was established in 1998 in a clayey Oxisol in southern Brazil following a completely randomized blocks design with a split-plot arrangement and three replications. Lime and gypsum were surface applied in 1998 and reapplied in 2013. Undisturbed soil samples were collected before the treatments reapplications, and one year after. The incubation experiment was carried out during 16months using these samples adding crop residues on the soil surface to simulate no-till field conditions. Lime and gypsum applications significantly increased the labile SOC stocks, microbial activity and soil fertility attributes in both field and laboratory experiments. Although the microbial activity was increased, no depletion of SOC stocks was observed in both experiments. Positive correlations were observed between microbial activity increase and SOC gains. Labile SOC and Ca 2+ content increase leads to forming complex with mineral soil fractions. Gypsum applications performed a higher influence on labile SOC pools in the field than in the laboratory experiment, which may be related to the presence of active root system in the soil profile. We conclude that incubation experiments using lime and gypsum in undisturbed samples confirm that soil microbial activity increase does not deplete SOC stocks under conservation agriculture

  16. Planting increases the abundance and structure complexity of soil core functional genes relevant to carbon and nitrogen cycling.

    Science.gov (United States)

    Wang, Feng; Liang, Yuting; Jiang, Yuji; Yang, Yunfeng; Xue, Kai; Xiong, Jinbo; Zhou, Jizhong; Sun, Bo

    2015-09-23

    Plants have an important impact on soil microbial communities and their functions. However, how plants determine the microbial composition and network interactions is still poorly understood. During a four-year field experiment, we investigated the functional gene composition of three types of soils (Phaeozem, Cambisols and Acrisol) under maize planting and bare fallow regimes located in cold temperate, warm temperate and subtropical regions, respectively. The core genes were identified using high-throughput functional gene microarray (GeoChip 3.0), and functional molecular ecological networks (fMENs) were subsequently developed with the random matrix theory (RMT)-based conceptual framework. Our results demonstrated that planting significantly (P soils and 83.5% of microbial alpha-diversity can be explained by the plant factor. Moreover, planting had significant impacts on the microbial community structure and the network interactions of the microbial communities. The calculated network complexity was higher under maize planting than under bare fallow regimes. The increase of the functional genes led to an increase in both soil respiration and nitrification potential with maize planting, indicating that changes in the soil microbial communities and network interactions influenced ecological functioning.

  17. Increase of rotation angle of soil layers during plow operation

    Science.gov (United States)

    Vasilenko, VV; Afonichev, D. N.; Vasilenko, S. V.; Khakhulin, A. N.

    2018-03-01

    One of the advantages of plowing is the ability of the plow to hide the weed seeds deep into the soil. The depth of the embankment exceeds 10-12 cm, from there the weeds can not rise to the surface of the soil. They perish halfway. But for this, it is necessary to wrap the soil layers at an angle close to 180 °. Modern ploughs can not turn the layers of soil at an angle of more than 135 °, therefore the plow is required to be equipped with additional working elements. The aim of the study is to create an adaptation to the plow to expand the furrow before laying the next soil layer. In a wide furrow, the formation will completely tip, the previous layer will not interfere with it. The device is a set of vertical shields. Each shield is fixed behind the working body of the plow. It is installed with an angle of attack of 20-25 ° to move the previous layer to expand the furrow by 10-12 cm. The model and industrial samples of the plow have shown improved agrotechnical indicators. The average angle of the formation rotation was 177 °, the burial of plant residues in the soil increased from 61 to 99%. The field surface with blocks more than 5 cm decreased from 36.3 to 13.4%, the height of the ridges decreased from 7 to 4 cm. The force of soil pressure on the shield was measured by a strain gage. It is 130-330 N depending on the depth of processing and the speed of movement. The increase in power costs for the four-hull plow was 190-750 W. The coulters on the plow are unnecessary, and this saves energy more than its increase for shields.

  18. 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.

  19. Assessment the effect of homogenized soil on soil hydraulic properties and soil water transport

    Science.gov (United States)

    Mohawesh, O.; Janssen, M.; Maaitah, O.; Lennartz, B.

    2017-09-01

    Soil hydraulic properties play a crucial role in simulating water flow and contaminant transport. Soil hydraulic properties are commonly measured using homogenized soil samples. However, soil structure has a significant effect on the soil ability to retain and to conduct water, particularly in aggregated soils. In order to determine the effect of soil homogenization on soil hydraulic properties and soil water transport, undisturbed soil samples were carefully collected. Five different soil structures were identified: Angular-blocky, Crumble, Angular-blocky (different soil texture), Granular, and subangular-blocky. The soil hydraulic properties were determined for undisturbed and homogenized soil samples for each soil structure. The soil hydraulic properties were used to model soil water transport using HYDRUS-1D.The homogenized soil samples showed a significant increase in wide pores (wCP) and a decrease in narrow pores (nCP). The wCP increased by 95.6, 141.2, 391.6, 3.9, 261.3%, and nCP decreased by 69.5, 10.5, 33.8, 72.7, and 39.3% for homogenized soil samples compared to undisturbed soil samples. The soil water retention curves exhibited a significant decrease in water holding capacity for homogenized soil samples compared with the undisturbed soil samples. The homogenized soil samples showed also a decrease in soil hydraulic conductivity. The simulated results showed that water movement and distribution were affected by soil homogenizing. Moreover, soil homogenizing affected soil hydraulic properties and soil water transport. However, field studies are being needed to find the effect of these differences on water, chemical, and pollutant transport under several scenarios.

  20. Increasing atmospheric deposition nitrogen and ammonium reduced microbial activity and changed the bacterial community composition of red paddy soil.

    Science.gov (United States)

    Zhou, Fengwu; Cui, Jian; Zhou, Jing; Yang, John; Li, Yong; Leng, Qiangmei; Wang, Yangqing; He, Dongyi; Song, Liyan; Gao, Min; Zeng, Jun; Chan, Andy

    2018-03-27

    Atmospheric deposition nitrogen (ADN) increases the N content in soil and subsequently impacts microbial activity of soil. However, the effects of ADN on paddy soil microbial activity have not been well characterized. In this study, we studied how red paddy soil microbial activity responses to different contents of ADN through a 10-months ADN simulation on well managed pot experiments. Results showed that all tested contents of ADN fluxes (27, 55, and 82kgNha -1 when its ratio of NH 4 + /NO 3 - -N (R N ) was 2:1) enhanced the soil enzyme activity and microbial biomass carbon and nitrogen and 27kgNha -1 ADN had maximum effects while comparing with the fertilizer treatment. Generally, increasing of both ADN flux and R N (1:2, 1:1 and 2:1 with the ADN flux of 55kgNha -1 ) had similar reduced effects on microbial activity. Furthermore, both ADN flux and R N significantly reduced soil bacterial alpha diversity (pADN flux and R N were the main drivers in shaping paddy soil bacteria community. Overall, the results have indicated that increasing ADN flux and ammonium reduced soil microbial activity and changed the soil bacterial community. The finding highlights how paddy soil microbial community response to ADN and provides information for N management in paddy soil. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Significant relationship between soil bacterial community structure and incidence of bacterial wilt disease under continuous cropping system.

    Science.gov (United States)

    She, Siyuan; Niu, Jiaojiao; Zhang, Chao; Xiao, Yunhua; Chen, Wu; Dai, Linjian; Liu, Xueduan; Yin, Huaqun

    2017-03-01

    Soil bacteria are very important in biogeochemical cycles and play significant role in soil-borne disease suppression. Although continuous cropping is responsible for soil-borne disease enrichment, its effect on tobacco plant health and how soil bacterial communities change are yet to be elucidated. In this study, soil bacterial communities across tobacco continuous cropping time-series fields were investigated through high-throughput sequencing of 16S ribosomal RNA genes. The results showed that long-term continuous cropping could significantly alter soil microbial communities. Bacterial diversity indices and evenness indices decreased over the monoculture span and obvious variations for community structures across the three time-scale tobacco fields were detected. Compared with the first year, the abundances of Arthrobacter and Lysobacter showed a significant decrease. Besides, the abundance of the pathogen Ralstonia spp. accumulated over the monoculture span and was significantly correlated with tobacco bacterial wilt disease rate. Moreover, Pearson's correlation demonstrated that the abundance of Arthrobacter and Lysobacter, which are considered to be beneficial bacteria had significant negative correlation with tobacco bacterial wilt disease. Therefore, after long-term continuous cropping, tobacco bacterial wilt disease could be ascribed to the alteration of the composition as well as the structure of the soil microbial community.

  2. Medicinal significance of vegetables cultivated over minerals supplemented soil

    International Nuclear Information System (INIS)

    Bangash, J.A.; Arif, M.; Khan, F.; Khan, F.; Khan, A.S.

    2010-01-01

    Three winter season vegetables Fenugreek/Methi (Trigonella-foenum-graceum), Sarson (Brassica-campestris-var-sarson) and Garlic (Allium-sativum) were included in the present study to determine some of their mineral components and see if some of their mineral (Cr, Zn, Mn, Cu, Mg and Fe) content could be increased by supplementation through their roots. Thus calculated amount of Cr, Zn, Mn, Cu, Mg and Fe salts (as fertilizer) were applied in solution form to the roots of vegetables in different concentration as individual or in combinations. These vegetables were grown from seeds in the soil plot. After harvesting vegetables were dried, acid digested and analyzed for Cr, Mn, Zn, Cu, Fe and Mg on Hitachi Zeeman Japan Z-8000, Atomic Absorption Spectrophotometer. Thus in Fenugreek/Methi (Trigonella-foenum-graceum) total increase of Cr, Zn, Mn, Mg and Fe recorded was (10, 94, 10, 256 and 520) mg/Kg dry weight basis; in Sarson (Brassica-campestris-var-sarson) total increase of Cr, Zn, Mn and Mg recorded was (12, 30, 22 and 424) mg/Kg dry weight basis and ( Garlic) (Allium-sativum) total increase of Cr, Zn, Mn, Cu, Mg and Fe recorded was (14, 28, 4, 4, 116 and 10) mg/Kg dry weight basis. From the present study it can be concluded that by changing the soil minerals environment the uptake of required mineral content of vegetables, perhaps could be enhanced. This could play important role in management of diabetes control and also in the elimination of other deficiency diseases like anemia. (author)

  3. Plant-based assessment of inherent soil productivity and contributions to China's cereal crop yield increase since 1980.

    Directory of Open Access Journals (Sweden)

    Mingsheng Fan

    Full Text Available OBJECTIVE: China's food production has increased 6-fold during the past half-century, thanks to increased yields resulting from the management intensification, accomplished through greater inputs of fertilizer, water, new crop strains, and other Green Revolution's technologies. Yet, changes in underlying quality of soils and their effects on yield increase remain to be determined. Here, we provide a first attempt to quantify historical changes in inherent soil productivity and their contributions to the increase in yield. METHODS: The assessment was conducted based on data-set derived from 7410 on-farm trials, 8 long-term experiments and an inventory of soil organic matter concentrations of arable land. RESULTS: Results show that even without organic and inorganic fertilizer addition crop yield from on-farm trials conducted in the 2000s was significantly higher compared with those in the 1980s - the increase ranged from 0.73 to 1.76 Mg/ha for China's major irrigated cereal-based cropping systems. The increase in on-farm yield in control plot since 1980s was due primarily to the enhancement of soil-related factors, and reflected inherent soil productivity improvement. The latter led to higher and stable yield with adoption of improved management practices, and contributed 43% to the increase in yield for wheat and 22% for maize in the north China, and, 31%, 35% and 22% for early and late rice in south China and for single rice crop in the Yangtze River Basin since 1980. CONCLUSIONS: Thus, without an improvement in inherent soil productivity, the 'Agricultural Miracle in China' would not have happened. A comprehensive strategy of inherent soil productivity improvement in China, accomplished through combining engineering-based measures with biological-approaches, may be an important lesson for the developing world. We propose that advancing food security in 21st century for both China and other parts of world will depend on continuously improving

  4. Priority areas in the Soil Framework Directive : the significance of soil biodiversity and ecosystem services

    NARCIS (Netherlands)

    Rutgers, M.; Jagers op Akkerhuis, G.A.J.M.; Bloem, J.

    2010-01-01

    Seven soil threats are distinguished in the draft text of the Soil Framework Directive of the European Commission. Soil organic matter decline and soil compaction are the most relevant for the Netherlands due to intensive agricultural land management. Loss of soil biodiversity should be considered

  5. Earthworms (Amynthas spp. increase common bean growth, microbial biomass, and soil respiration

    Directory of Open Access Journals (Sweden)

    Julierme Zimmer Barbosa

    2017-10-01

    Full Text Available Few studies have evaluated the effect of earthworms on plants and biological soil attributes, especially among legumes. The objective of this study was to evaluate the influence of earthworms (Amynthas spp. on growth in the common bean (Phaseolus vulgaris L. and on soil biological attributes. The experiment was conducted in a greenhouse using a completely randomized design with five treatments and eight repetitions. The treatments consisted of inoculation with five different quantities of earthworms of the genus Amynthas (0, 2, 4, 6, and 8 worms per pot. Each experimental unit consisted of a plastic pot containing 4 kg of soil and two common bean plants. The experiment was harvested 38 days after seedling emergence. Dry matter and plant height, soil respiration, microbial respiration, microbial biomass, and metabolic quotient were determined. Earthworm recovery in our study was high in number and mass, with all values above 91.6% and 89.1%, respectively. In addition, earthworm fresh biomass decreased only in the treatment that included eight earthworms per pot. The presence of earthworms increased the plant growth and improved soil biological properties, suggesting that agricultural practices that favor the presence of these organisms can be used to increase the production of common bean, and the increased soil CO2 emission caused by the earthworms can be partially offset by the addition of common bean crop residues to the soil.

  6. Hydrodynamic behaviour of crusted soils in the Sahel: a possible cause for runoff increase?

    Science.gov (United States)

    Malam Abdou, M.; Vandervaere, J.-P.; Bouzou Moussa, I.; Descroix, L.

    2012-04-01

    Crusted soils are in extension in the Sahel. As rainfall has decreased over the past decades (it is now increasing again in the central Sahel) and no significant change was observed in rainfall intensity and in its time and space distribution, it is supposed that land use management is the main cause for crusts cover increase. Fallow shortening, lack of manure, and land overexploitation (wood harvesting, overgrazing) are frequently cited as main factors of soil degradation. Based on field measurements in some small catchments of Western Niger, the hydrodynamics behaviour of the newly crusted soils of this area is described, mostly constituted by erosion crusts. A strong fall in soil saturated conductivity and in the active porosity as well as a rise in bulk density all lead to a quick onset of runoff production. Results are shown from field experiments in sedimentary and basement areas leading to similar conclusions. In both contexts, runoff plot production was measured at the rain event scale from 10-m2 parcels as well as at the catchment outlet. Soil saturated conductivity was reduced by one order of magnitude when crusting occurs, leading to a sharp runoff coefficient increase, from 4% in a weeded millet field and 10% in an old fallow to more than 60% in a erosion-crusted topsoil at the plot scale. At the experimental catchment scale, runoff coefficient has doubled in less than 20 years. In pure Sahelian basins, this resulted in endorheism breaching, and in a widespread river discharge increase. For some right bank tributaries of the Niger River, discharge is three times higher now than before the drought years, in spite of the remaining rainfall deficit. On the other hand, a general increase in flooding hazard frequency is observed in the whole Sahelian stripe. The role of surface crusts in the Sahel is discussed leading to the implementation of new experiments in the future.

  7. Reduced tillage and cover crops as a strategy for mitigating atmospheric CO2 increase through soil organic carbon sequestration in dry Mediterranean agroecosystems.

    Science.gov (United States)

    Almagro, María; Garcia-Franco, Noelia; de Vente, Joris; Boix-Fayos, Carolina; Díaz-Pereira, Elvira; Martínez-Mena, María

    2016-04-01

    The implementation of sustainable land management (SLM) practices in semiarid Mediterranean agroecosystems can be beneficial to maintain or enhance levels of soil organic carbon and mitigate current atmospheric CO2 increase. In this study, we assess the effects of different tillage treatments (conventional tillage (CT), reduced tillage (RT), reduced tillage combined with green manure (RTG), and no tillage (NT)) on soil CO2 efflux, aggregation and organic carbon stabilization in two semiarid organic rainfed almond (Prunus dulcis Mill., var. Ferragnes) orchards located in SE Spain Soil CO2 efflux, temperature and moisture were measured monthly between May 2012 and December 2014 (site 1), and between February 2013 and December 2014 (site 2). In site 1, soil CO2 efflux rates were also measured immediately following winter and spring tillage operations. Aboveground biomass inputs were estimated at the end of the growing season in each tillage treatment. Soil samples (0-15 cm) were collected in the rows between the trees (n=4) in October 2012. Four aggregate size classes were distinguished by sieving (large and small macroaggregates, free microaggregates, and free silt plus clay fraction), and the microaggregates occluded within macroaggregates (SMm) were isolated. Soil CO2efflux rates in all tillage treatments varied significantly during the year, following changes during the autumn, winter and early spring, or changes in soil moisture during late spring and summer. Repeated measures analyses of variance revealed that there were no significant differences in soil CO2 efflux between tillage treatments throughout the study period at both sites. Average annual values of C lost by soil respiration were slightly but not significantly higher under RT and RTG treatments (492 g C-CO2 m-2 yr-1) than under NT treatment (405 g C-CO2 m-2 yr-1) in site 1, while slightly but not significantly lower values were observed under RT and RTG treatments (468 and 439 g C-CO2 m-2 yr-1

  8. Copper Pollution Increases the Resistance of Soil Archaeal Community to Changes in Water Regime.

    Science.gov (United States)

    Li, Jing; Liu, Yu-Rong; Cui, Li-Juan; Hu, Hang-Wei; Wang, Jun-Tao; He, Ji-Zheng

    2017-11-01

    Increasing efforts have been devoted to exploring the impact of environmental stresses on soil bacterial communities, but the work on the archaeal community is seldom. Here, we constructed microcosm experiments to investigate the responses of archaeal communities to the subsequent dry-rewetting (DW) disturbance in two contrasting soils (fluvo-aquic and red soil) after 6 years of copper pollution. Ten DW cycles were exerted on the two soils with different copper levels, followed by a 6-week recovery period. In both soils, archaeal diversity (Shannon index) in the high copper-level treatments increased over the incubation period, and archaeal community structure changed remarkably as revealed by the non-metric multidimensional scaling ordinations. In both soils, copper pollution altered the response of dominant operational taxonomic units (OTUs) to the DW disturbance. Throughout the incubation and recovery period, the resistance of archaeal abundance to the DW disturbance was higher in the copper-polluted soils than soils without pollution. Taken together, copper pollution altered the response of soil archaeal diversity and community composition to the DW disturbance and increased the resistance of the archaeal abundance. These findings have important implications for understanding soil microbial responses to ongoing environmental change.

  9. Engineered biochar from microwave-assisted catalytic pyrolysis of switchgrass for increasing water-holding capacity and fertility of sandy soil

    International Nuclear Information System (INIS)

    Mohamed, Badr A.; Ellis, Naoko; Kim, Chang Soo; Bi, Xiaotao; Emam, Ahmed El-raie

    2016-01-01

    Engineered biochars produced from microwave-assisted catalytic pyrolysis of switchgrass have been evaluated in terms of their ability on improving water holding capacity (WHC), cation exchange capacity (CEC) and fertility of loamy sand soil. The addition of K 3 PO 4 , clinoptilolite and/or bentonite as catalysts during the pyrolysis process increased biochar surface area and plant nutrient contents. Adding biochar produced with 10 wt.% K 3 PO 4 + 10 wt.% clinoptilolite as catalysts to the soil at 2 wt% load increased soil WHC by 98% and 57% compared to the treatments without biochar (control) and with 10 wt.% clinoptilolite, respectively. Synergistic effects on increased soil WHC were manifested for biochars produced from combinations of two additives compared to single additive, which may be the result of increased biochar microporosity due to increased microwave heating rate. Biochar produced from microwave catalytic pyrolysis was more efficient in increasing the soil WHC due to its high porosity in comparison with the biochar produced from conventional pyrolysis at the same conditions. The increases in soil CEC varied widely compared to the control soil, ranging from 17 to 220% for the treatments with biochars produced with 10 wt% clinoptilolite at 400 °C, and 30 wt% K 3 PO 4 at 300 °C, respectively. Strong positive correlations also exist among soil WHC with CEC and biochar micropore area. Biochar from microwave-assisted catalytic pyrolysis appears to be a novel approach for producing biochar with high sorption affinity and high CEC. These catalysts remaining in the biochar product would provide essential nutrients for the growth of bioenergy and food crops. - Highlights: • High quality biochar was made by catalytic pyrolysis in a microwave reactor. • High heating rate and good biochar quality were achieved using K 3 PO 4 and clinoptilolite mixture. • Biochars showed significant increase in soil WHC and CEC. • Microwave catalytic pyrolysis can produce

  10. Engineered biochar from microwave-assisted catalytic pyrolysis of switchgrass for increasing water-holding capacity and fertility of sandy soil

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, Badr A. [Department of Chemical and Biological Engineering, University of British Columbia, Vancouver BC V6T 1Z3 (Canada); Agricultural Engineering Department, Cairo University, Giza (Egypt); Ellis, Naoko [Department of Chemical and Biological Engineering, University of British Columbia, Vancouver BC V6T 1Z3 (Canada); Kim, Chang Soo [Department of Chemical and Biological Engineering, University of British Columbia, Vancouver BC V6T 1Z3 (Canada); Clean Energy Research Center, Korea Institute of Science and Technology, 14 gil 5 Hwarang-no Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Bi, Xiaotao, E-mail: tony.bi@ubc.ca [Department of Chemical and Biological Engineering, University of British Columbia, Vancouver BC V6T 1Z3 (Canada); Emam, Ahmed El-raie [Agricultural Engineering Department, Cairo University, Giza (Egypt)

    2016-10-01

    Engineered biochars produced from microwave-assisted catalytic pyrolysis of switchgrass have been evaluated in terms of their ability on improving water holding capacity (WHC), cation exchange capacity (CEC) and fertility of loamy sand soil. The addition of K{sub 3}PO{sub 4}, clinoptilolite and/or bentonite as catalysts during the pyrolysis process increased biochar surface area and plant nutrient contents. Adding biochar produced with 10 wt.% K{sub 3}PO{sub 4} + 10 wt.% clinoptilolite as catalysts to the soil at 2 wt% load increased soil WHC by 98% and 57% compared to the treatments without biochar (control) and with 10 wt.% clinoptilolite, respectively. Synergistic effects on increased soil WHC were manifested for biochars produced from combinations of two additives compared to single additive, which may be the result of increased biochar microporosity due to increased microwave heating rate. Biochar produced from microwave catalytic pyrolysis was more efficient in increasing the soil WHC due to its high porosity in comparison with the biochar produced from conventional pyrolysis at the same conditions. The increases in soil CEC varied widely compared to the control soil, ranging from 17 to 220% for the treatments with biochars produced with 10 wt% clinoptilolite at 400 °C, and 30 wt% K{sub 3}PO{sub 4} at 300 °C, respectively. Strong positive correlations also exist among soil WHC with CEC and biochar micropore area. Biochar from microwave-assisted catalytic pyrolysis appears to be a novel approach for producing biochar with high sorption affinity and high CEC. These catalysts remaining in the biochar product would provide essential nutrients for the growth of bioenergy and food crops. - Highlights: • High quality biochar was made by catalytic pyrolysis in a microwave reactor. • High heating rate and good biochar quality were achieved using K{sub 3}PO{sub 4} and clinoptilolite mixture. • Biochars showed significant increase in soil WHC and CEC.

  11. Acacia Changes Microbial Indicators and Increases C and N in Soil Organic Fractions in Intercropped Eucalyptus Plantations

    Directory of Open Access Journals (Sweden)

    Arthur P. A. Pereira

    2018-04-01

    Full Text Available Intercropping forest plantations of Eucalyptus with nitrogen-fixing trees can increase soil N inputs and stimulate soil organic matter (OM cycling. However, microbial indicators and their correlation in specific fractions of soil OM are unclear in the tropical sandy soils. Here, we examined the microbial indicators associated with C and N in the soil resulting from pure and intercropped Eucalyptus grandis and Acacia mangium plantations. We hypothesized that introduction of A. mangium in a Eucalyptus plantation promotes changes in microbial indicators and increases C and N concentrations on labile fractions of the soil OM, when compared to pure eucalyptus plantations. We determined the microbial and enzymatic activity, and the potential for C degradation by the soil microbial community. Additionally, we evaluated soil OM fractions and litter parameters. Soil (0–20 cm and litter samples were collected at 27 and 39 months after planting from the following treatments: pure E. grandis (E and A. mangium (A plantations, pure E. grandis plantations with N fertilizer (E+N and an E. grandis, and A. mangium intercropped plantations (E+A. The results showed that intercropped plantations (E+A increase 3, 45, and 70% microbial biomass C as compared to A, E+N, and E, at 27 months after planting. The metabolic quotient (qCO2 showed a tendency toward stressful values in pure E. grandis plantations and a strong correlation with dehydrogenase activity. A and E+A treatments also exhibited the highest organic fractions (OF and C and N contents. A canonical redundancy analysis revealed positive correlations between microbial indicators of soil and litter attributes, and a strong effect of C and N variables in differentiating A and E+A from E and E+N treatments. The results suggested that a significant role of A. mangium enhance the dynamics of soil microbial indicators which help in the accumulation of C and N in soil OF in intercropped E. grandis plantations. Our

  12. Acacia Changes Microbial Indicators and Increases C and N in Soil Organic Fractions in Intercropped Eucalyptus Plantations

    Science.gov (United States)

    Pereira, Arthur P. A.; Zagatto, Maurício R. G.; Brandani, Carolina B.; Mescolotti, Denise de Lourdes; Cotta, Simone R.; Gonçalves, José L. M.; Cardoso, Elke J. B. N.

    2018-01-01

    Intercropping forest plantations of Eucalyptus with nitrogen-fixing trees can increase soil N inputs and stimulate soil organic matter (OM) cycling. However, microbial indicators and their correlation in specific fractions of soil OM are unclear in the tropical sandy soils. Here, we examined the microbial indicators associated with C and N in the soil resulting from pure and intercropped Eucalyptus grandis and Acacia mangium plantations. We hypothesized that introduction of A. mangium in a Eucalyptus plantation promotes changes in microbial indicators and increases C and N concentrations on labile fractions of the soil OM, when compared to pure eucalyptus plantations. We determined the microbial and enzymatic activity, and the potential for C degradation by the soil microbial community. Additionally, we evaluated soil OM fractions and litter parameters. Soil (0–20 cm) and litter samples were collected at 27 and 39 months after planting from the following treatments: pure E. grandis (E) and A. mangium (A) plantations, pure E. grandis plantations with N fertilizer (E+N) and an E. grandis, and A. mangium intercropped plantations (E+A). The results showed that intercropped plantations (E+A) increase 3, 45, and 70% microbial biomass C as compared to A, E+N, and E, at 27 months after planting. The metabolic quotient (qCO2) showed a tendency toward stressful values in pure E. grandis plantations and a strong correlation with dehydrogenase activity. A and E+A treatments also exhibited the highest organic fractions (OF) and C and N contents. A canonical redundancy analysis revealed positive correlations between microbial indicators of soil and litter attributes, and a strong effect of C and N variables in differentiating A and E+A from E and E+N treatments. The results suggested that a significant role of A. mangium enhance the dynamics of soil microbial indicators which help in the accumulation of C and N in soil OF in intercropped E. grandis plantations. Our results are

  13. Acacia Changes Microbial Indicators and Increases C and N in Soil Organic Fractions in Intercropped Eucalyptus Plantations.

    Science.gov (United States)

    Pereira, Arthur P A; Zagatto, Maurício R G; Brandani, Carolina B; Mescolotti, Denise de Lourdes; Cotta, Simone R; Gonçalves, José L M; Cardoso, Elke J B N

    2018-01-01

    Intercropping forest plantations of Eucalyptus with nitrogen-fixing trees can increase soil N inputs and stimulate soil organic matter (OM) cycling. However, microbial indicators and their correlation in specific fractions of soil OM are unclear in the tropical sandy soils. Here, we examined the microbial indicators associated with C and N in the soil resulting from pure and intercropped Eucalyptus grandis and Acacia mangium plantations. We hypothesized that introduction of A. mangium in a Eucalyptus plantation promotes changes in microbial indicators and increases C and N concentrations on labile fractions of the soil OM, when compared to pure eucalyptus plantations. We determined the microbial and enzymatic activity, and the potential for C degradation by the soil microbial community. Additionally, we evaluated soil OM fractions and litter parameters. Soil (0-20 cm) and litter samples were collected at 27 and 39 months after planting from the following treatments: pure E. grandis (E) and A. mangium (A) plantations, pure E. grandis plantations with N fertilizer (E+N) and an E. grandis , and A. mangium intercropped plantations (E+A). The results showed that intercropped plantations (E+A) increase 3, 45, and 70% microbial biomass C as compared to A, E+N, and E, at 27 months after planting. The metabolic quotient ( q CO 2 ) showed a tendency toward stressful values in pure E. grandis plantations and a strong correlation with dehydrogenase activity. A and E+A treatments also exhibited the highest organic fractions (OF) and C and N contents. A canonical redundancy analysis revealed positive correlations between microbial indicators of soil and litter attributes, and a strong effect of C and N variables in differentiating A and E+A from E and E+N treatments. The results suggested that a significant role of A. mangium enhance the dynamics of soil microbial indicators which help in the accumulation of C and N in soil OF in intercropped E. grandis plantations. Our results

  14. Soil microbes and soil respiration of Mongolian Steppe soils under grazing stress.

    Science.gov (United States)

    Bölter, Manfred; Krümmelbein, Julia; Horn, Rainer; Möller, Rolf; Scheltz, Annette

    2012-04-01

    Soils of Northern China were analysed for their microbiological and soil physical properties with respect to different grazing stress. An important factor for this is soil compaction and related aeration due to pore size shifts. Bulk density increases significantly with increasing grazing intensity and soil carbon contents show decreasing values from top to depth. Organic carbon (LOI) concentrations decrease significantly with increasing grazing intensity. The data on LOI (2-5.8%) approximate 10-30 mg C, our data on glucose show values between 0.4-1.2 mg, i.e. approx. 4% of total carbon. Numbers and biomass of bacteria show generally a decreasing trend of those data at grazed and ungrazed sites, numbers range between 0.4 and 8.7 x10(8) g(-1) d.wt., bacterial biomass between 0.4 and 3.8 microg Cg(-1). This need to be recorded in relation to soil compaction and herewith-hampered aeration and nutrient flow. The temperature-respiration data also allow getting an idea of the Q10-values for soil respiration. The data are between 2.24 (5-15 degrees C) and 1.2 (25-35 degrees C). Our data are presented with a general review of biological properties of Mongolian Steppe soils.

  15. Low moisture availability inhibits the enhancing effect of increased soil temperature on net photosynthesis of white birch (Betula papyrifera) seedlings grown under ambient and elevated carbon dioxide concentrations.

    Science.gov (United States)

    Ambebe, Titus F; Dang, Qing-Lai

    2009-11-01

    White birch (Betula papyrifera Marsh.) seedlings were grown under two carbon dioxide concentrations (ambient: 360 micromol mol(-1) and elevated: 720 micromol mol(-1)), three soil temperatures (5, 15 and 25 degrees C initially, increased to 7, 17 and 27 degrees C, respectively, 1 month later) and three moisture regimes (low: 30-40%; intermediate: 45-55% and high: 60-70% field water capacity) in greenhouses. In situ gas exchange and chlorophyll fluorescence were measured after 2 months of treatments. Net photosynthetic rate (A(n)) of seedlings grown under the intermediate and high moisture regimes increased from low to intermediate T(soil) and then decreased to high T(soil). There were no significant differences between the low and high T(soil), with the exception that A(n) was significantly higher under high than low T(soil) at the high moisture regime. No significant T(soil) effect on A(n) was observed at the low moisture regime. The intermediate T(soil) increased stomatal conductance (g(s)) only at intermediate and high but not at low moisture regime, whereas there were no significant differences between the low and high T(soil) treatments. Furthermore, the difference in g(s) between the intermediate and high T(soil) at high moisture regime was not statistically significant. The low moisture regime significantly reduced the internal to ambient CO2 concentration ratio at all T(soil). There were no significant individual or interactive effects of treatment on maximum carboxylation rate of Rubisco, light-saturated electron transport rate, triose phosphate utilization or potential photochemical efficiency of photosystem II. The results of this study suggest that soil moisture condition should be taken into account when predicting the responses of white birch to soil warming.

  16. Seasonal Patterns of Soil Respiration and Related Soil Biochemical Properties under Nitrogen Addition in Winter Wheat Field.

    Science.gov (United States)

    Liang, Guopeng; Houssou, Albert A; Wu, Huijun; Cai, Dianxiong; Wu, Xueping; Gao, Lili; Li, Jing; Wang, Bisheng; Li, Shengping

    2015-01-01

    Understanding the changes of soil respiration under increasing N fertilizer in cropland ecosystems is crucial to accurately predicting global warming. This study explored seasonal variations of soil respiration and its controlling biochemical properties under a gradient of Nitrogen addition during two consecutive winter wheat growing seasons (2013-2015). N was applied at four different levels: 0, 120, 180 and 240 kg N ha(-1) year(-1) (denoted as N0, N12, N18 and N24, respectively). Soil respiration exhibited significant seasonal variation and was significantly affected by soil temperature with Q10 ranging from 2.04 to 2.46 and from 1.49 to 1.53 during 2013-2014 and 2014-2015 winter wheat growing season, respectively. Soil moisture had no significant effect on soil respiration during 2013-2014 winter wheat growing season but showed a significant and negative correlation with soil respiration during 2014-2015 winter wheat growing season. Soil respiration under N24 treatment was significantly higher than N0 treatment. Averaged over the two growing seasons, N12, N18 and N24 significantly increased soil respiration by 13.4, 16.4 and 25.4% compared with N0, respectively. N addition also significantly increased easily extractable glomalin-related soil protein (EEG), soil organic carbon (SOC), total N, ammonium N and nitrate N contents. In addition, soil respiration was significantly and positively correlated with β-glucosidase activity, EEG, SOC, total N, ammonium N and nitrate N contents. The results indicated that high N fertilization improved soil chemical properties, but significantly increased soil respiration.

  17. Significance of agricultural row structure on the microwave emissivity of soils

    Science.gov (United States)

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

    1987-01-01

    A series of field experiments was carried out to extend the data base available for verifying agricultural row effect models of emissivity. The row effects model was used to simulate a data base from which an algorithm could be developed to account for row effects when the scene dielectric constant and small-scale roughness are unknown. One objective of the study was to quantify the significance of row structure and to develop a practical procedure for removing the effects of periodic row structure on the microwave emissivity of a soil in order to use the emissivity values to estimate the soil moisture. A second objective was to expand the data set available for model verification through field observations using a truck-mounted 1.4-GHz microwave radiometer.

  18. Grazing disturbance increases transient but decreases persistent soil seed bank.

    Science.gov (United States)

    Ma, Miaojun; Walck, Jeffrey L; Ma, Zhen; Wang, Lipei; Du, Guozhen

    2018-04-30

    Very few studies have examined whether the impacts of grazing disturbance on soil seed banks occur directly or indirectly through aboveground vegetation and soil properties. The potential role of the seed bank in alpine wetland restoration is also unknown. We used SEM (structural equation modeling) to explore the direct effect of grazing disturbance on the seed bank and the indirect effect through aboveground vegetation and soil properties. We also studied the role of the seed bank on the restoration potential in wetlands with various grazing intensities: low (fenced, winter grazed only), medium (seasonally grazed), and high (whole-year grazed). For the seed bank, species richness and density per plot showed no difference among grazing intensities for each depth (0-5, 5-10, 10-15 cm) and for the whole depth (0-15 cm) in spring and summer. There was no direct effect of grazing disturbance on seed bank richness and density both in spring and summer, and also no indirect effect on the seed bank through its direct effect on vegetation richness and abundance. Grazing disturbance indirectly increased spring seed bank density but decreased summer seed bank density through its direct effect (negative correlation) on soil moisture and total nitrogen and its indirect effect on vegetation abundance. Species composition of the vegetation changed with grazing regime, but that of the seed bank did not. An increased trend of similarity between the seed bank and aboveground vegetation with increased grazing disturbance was found in the shallow depth and in the whole depth only in spring. Although there was almost no change in seed bank size with grazing intensities, grazing disturbance increased the quantity of transient seeds but decreased persistent seeds. Persistent seeds stored in the soil could play a crucial role in vegetation regeneration and in restoration of degraded wetland ecosystems. The seed bank should be an integral part of alpine wetland restoration programs.

  19. Parametrization of the increase of the aeolian erosion threshold wind friction velocity due to soil moisture for arid and semi-arid areas

    Directory of Open Access Journals (Sweden)

    F. Fécan

    1999-01-01

    Full Text Available Large-scale simulation of the soil-derived dust emission in semi-arid regions needs to account for the influence of the soil moisture on the wind erosion threshold. Soil water retention consists of molecular adsorption on the soil grain surface and capillary forces between the grain. Interparticle capillary forces (characterized by the moisture tension are the main factor responsible for the increase of the wind erosion threshold observed when the soil moisture increases. When the soil moisture content is close to but smaller than the maximum amount of adsorbed water, w' (depending on the soil texture, these capillary forces are considered as not strong enough to significantly increase the erosion threshold. An expression of the moisture tension as a function of soil moisture and w' is derived from retention curves. From this expression, a parametrization of the ratio of the wet to dry erosion thresholds has been developed as a function of soil moisture and soil texture. The coefficients of this parametrization have been determined by using experimental data from the literature. An empirical relationship between w' and soil clay content has been established. The erosion threshold ratios simulated for different soil textures were found to be in good agreement with the experimental data.Key words. Atmospheric composition and structure (Aerosols and particles · Hydrology (soil moisture

  20. Plants increase laccase activity in soil with long-term elevated CO2 legacy

    DEFF Research Database (Denmark)

    Partavian, Asrin; Mikkelsen, Teis Nørgaard; Vestergård, Mette

    2015-01-01

    [CO2] stimulate laccase activity. We incubated soil exposed to seven years of elevated or ambient field [CO2] in ambient or elevated [CO2] chambers for six months either with or without plants (Deschampsia flexuosa). Elevated chamber [CO2] increased D. flexuosa production and belowground respiration....... Interestingly, plants also grew larger in soil with an elevated [CO2] legacy. Plants stimulated soil microbial biomass, belowground respiration and laccase activity, and the plant-induced laccase stimulation was particularly apparent in soil exposed to long-term elevated [CO2] in the field, whereas laccase......Actively growing plants can stimulate mineralization of recalcitrant soil organic matter (SOM), and increased atmospheric [CO2] can further enhance such plant-mediated SOM degradation. Laccases are central for recalcitrant SOM decomposition, and we therefore hypothesized that plants and elevated...

  1. Seasonal Patterns of Soil Respiration and Related Soil Biochemical Properties under Nitrogen Addition in Winter Wheat Field

    Science.gov (United States)

    Liang, Guopeng; Houssou, Albert A.; Wu, Huijun; Cai, Dianxiong; Wu, Xueping; Gao, Lili; Li, Jing; Wang, Bisheng; Li, Shengping

    2015-01-01

    Understanding the changes of soil respiration under increasing N fertilizer in cropland ecosystems is crucial to accurately predicting global warming. This study explored seasonal variations of soil respiration and its controlling biochemical properties under a gradient of Nitrogen addition during two consecutive winter wheat growing seasons (2013–2015). N was applied at four different levels: 0, 120, 180 and 240 kg N ha-1 year-1 (denoted as N0, N12, N18 and N24, respectively). Soil respiration exhibited significant seasonal variation and was significantly affected by soil temperature with Q10 ranging from 2.04 to 2.46 and from 1.49 to 1.53 during 2013–2014 and 2014–2015 winter wheat growing season, respectively. Soil moisture had no significant effect on soil respiration during 2013–2014 winter wheat growing season but showed a significant and negative correlation with soil respiration during 2014–2015 winter wheat growing season. Soil respiration under N24 treatment was significantly higher than N0 treatment. Averaged over the two growing seasons, N12, N18 and N24 significantly increased soil respiration by 13.4, 16.4 and 25.4% compared with N0, respectively. N addition also significantly increased easily extractable glomalin-related soil protein (EEG), soil organic carbon (SOC), total N, ammonium N and nitrate N contents. In addition, soil respiration was significantly and positively correlated with β-glucosidase activity, EEG, SOC, total N, ammonium N and nitrate N contents. The results indicated that high N fertilization improved soil chemical properties, but significantly increased soil respiration. PMID:26629695

  2. Forest-to-pasture conversion increases the diversity of the phylum Verrucomicrobia in Amazon rainforest soils.

    Science.gov (United States)

    Ranjan, Kshitij; Paula, Fabiana S; Mueller, Rebecca C; Jesus, Ederson da C; Cenciani, Karina; Bohannan, Brendan J M; Nüsslein, Klaus; Rodrigues, Jorge L M

    2015-01-01

    The Amazon rainforest is well known for its rich plant and animal diversity, but its bacterial diversity is virtually unexplored. Due to ongoing and widespread deforestation followed by conversion to agriculture, there is an urgent need to quantify the soil biological diversity within this tropical ecosystem. Given the abundance of the phylum Verrucomicrobia in soils, we targeted this group to examine its response to forest-to-pasture conversion. Both taxonomic and phylogenetic diversities were higher for pasture in comparison to primary and secondary forests. The community composition of Verrucomicrobia in pasture soils was significantly different from those of forests, with a 11.6% increase in the number of sequences belonging to subphylum 3 and a proportional decrease in sequences belonging to the class Spartobacteria. Based on 99% operational taxonomic unit identity, 40% of the sequences have not been detected in previous studies, underscoring the limited knowledge regarding the diversity of microorganisms in tropical ecosystems. The abundance of Verrucomicrobia, measured with quantitative PCR, was strongly correlated with soil C content (r = 0.80, P = 0.0016), indicating their importance in metabolizing plant-derived carbon compounds in soils.

  3. Facilitation by a Spiny Shrub on a Rhizomatous Clonal Herbaceous in Thicketization-Grassland in Northern China: Increased Soil Resources or Shelter from Herbivores

    Directory of Open Access Journals (Sweden)

    Saixiyala

    2017-05-01

    Full Text Available The formation of fertility islands by shrubs increases soil resources heterogeneity in thicketization-grasslands. Clonal plants, especially rhizomatous or stoloniferous clonal plants, can form large clonal networks and use heterogeneously distributed resources effectively. In addition, shrubs, especially spiny shrubs, may also provide herbaceous plants with protection from herbivores, acting as ‘shelters’. The interaction between pre-dominated clonal herbaceous plants and encroaching shrubs remains unclear in thicketization-grassland under grazing pressure. We hypothesized that clonal herbaceous plants can be facilitated by encroached shrubs as a ‘shelter from herbivores’ and/or as an ‘increased soil resources’ under grazing pressure. To test this hypothesis, a total of 60 quadrats were chosen in a thicket-grassland in northern China that was previously dominated by Leymus chinensis and was encroached upon by the spiny leguminous plant Caragana intermedia. The soil and plant traits beneath and outside the shrub canopies were sampled, investigated and contrasted with an enclosure. The soil organic matter, soil total nitrogen and soil water content were significantly higher in the soil beneath the shrub canopies than in the soil outside the canopies. L. chinensis beneath the shrub canopies had significantly higher plant height, single shoot biomass, leaf length and width than outside the shrub canopies. There were no significantly differences between plant growth in enclosure and outside the shrub canopies. These results suggested that under grazing pressure in a grassland undergoing thicketization, the growth of the rhizomatous clonal herbaceous plant L. chinensis was facilitated by the spiny shrub C. intermedia as a ‘shelter from herbivores’ more than through ‘increased soil resources’. We propose that future studies should focus on the community- and ecosystem-level impacts of plant clonality.

  4. Redox Fluctuations Increase the Contribution of Lignin to Soil Respiration

    Science.gov (United States)

    Hall, S. J.; Silver, W. L.; Timokhin, V.; Hammel, K.

    2014-12-01

    Lignin mineralization represents a critical flux in the terrestrial carbon (C) cycle, yet little is known about mechanisms and environmental factors controlling lignin breakdown in mineral soils. Hypoxia has long been thought to suppress lignin decomposition, yet variation in oxygen (O2) availability in surface soils accompanying moisture fluctuations could potentially stimulate this process by generating reactive oxygen species via coupled biotic and abiotic iron (Fe) redox cycling. Here, we tested the impact of redox fluctuations on lignin breakdown in humid tropical forest soils during ten-week laboratory incubations. We used synthetic lignins labeled with 13C in either of two positions (aromatic methoxyl and propyl Cβ) to provide highly sensitive and specific measures of lignin mineralization not previously employed in soils. Four-day redox fluctuations increased the percent contribution of methoxyl C to soil respiration, and cumulative methoxyl C mineralization was equivalent under static aerobic and fluctuating redox conditions despite lower total C mineralization in the latter treatment. Contributions of the highly stable Cβ to mineralization were also equivalent in static aerobic and fluctuating redox treatments during periods of O2 exposure, and nearly doubled in the fluctuating treatment after normalizing to cumulative O2 exposure. Oxygen fluctuations drove substantial net Fe reduction and oxidation, implying that reactive oxygen species generated during abiotic Fe oxidation likely contributed to the elevated contribution of lignin to C mineralization. Iron redox cycling provides a mechanism for lignin breakdown in soils that experience conditions unfavorable for canonical lignin-degrading organisms, and provides a potential mechanism for lignin depletion in soil organic matter during late-stage decomposition. Thus, close couplings between soil moisture, redox fluctuations, and lignin breakdown provide potential a link between climate variability and

  5. Alkanes as Components of Soil Hydrocarbon Status: Behavior and Indication Significance

    Science.gov (United States)

    Gennadiev, A. N.; Zavgorodnyaya, Yu. A.; Pikovskii, Yu. I.; Smirnova, M. A.

    2018-01-01

    Studies of soils on three key plots with different climatic conditions and technogenic impacts in Volgograd, Moscow, and Arkhangelsk oblasts have showed that alkanes in the soil exchange complex have some indication potential for the identification of soil processes. The following combinations of soil-forming factors and processes have been studied: (a) self-purification of soil after oil pollution; (b) accumulation of hydrocarbons coming from the atmosphere to soils of different land use patterns; and (c) changes in the soil hydrocarbon complex beyond the zone of technogenic impact due to the input of free hydrocarbon-containing gases. At the injection input of hydrocarbon pollutants, changes in the composition and proportions of alkanes allow tracing the degradation trend of pollutants in the soil from their initial content to the final stage of soil self-purification, when the background concentrations of hydrocarbons are reached. Upon atmospheric deposition of hydrocarbons onto the soil, from the composition and mass distribution of alkanes, conclusions can be drawn about the effect of toxicants on biogeochemical processes in the soil, including their manifestation under different land uses. Composition analysis of soil alkanes in natural landscapes can reveal signs of hydrocarbon emanation fluxes in soils. The indication potentials of alkanes in combination with polycyclic aromatic hydrocarbons and other components of soil hydrocarbon complex can also be used for the solution of other soil-geochemical problems.

  6. Soil warming increased whole-tree water use of Pinus cembra at the treeline in the Central Tyrolean Alps.

    Science.gov (United States)

    Wieser, Gerhard; Grams, Thorsten E E; Matyssek, Rainer; Oberhuber, Walter; Gruber, Andreas

    2015-03-01

    This study quantified the effect of soil warming on sap flow density (Qs) of Pinus cembra L. at the treeline in the Central Tyrolean Alps. To enhance soil temperature we installed a transparent roof construction above the forest floor around six trees. Six other trees served as controls in the absence of any manipulation. Roofing enhanced growing season mean soil temperature by 1.6, 1.3 and 1.0 °C at 5, 10 and 20 cm soil depth, respectively, while soil water availability was not affected. Sap flow density (using Granier-type thermal dissipation probes) and environmental parameters were monitored throughout three growing seasons. During the first year of treatment, no warming effect was detected on Qs. However, soil warming caused Qs to increase significantly by 11 and 19% above levels in control trees during the second and third year, respectively. This effect appeared to result from warming-induced root production, a reduction in viscosity and perhaps an increase also in root hydraulic conductivity. Hardly affected were leaf-level net CO2 uptake rate and conductance for water vapour, so that water-use efficiency stayed unchanged as confirmed by needle δ(13)C analysis. We conclude that tree water loss will increase with soil warming, which may alter the water balance within the treeline ecotone of the Central Austrian Alps in a future warming environment. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Nematodes Relevance in Soil Quality Management and their Significance as Biomarkers in Aquatic Substrates: Review.

    Science.gov (United States)

    Akpheokhai, Leonard I; Oribhabor, Blessing J

    2016-01-01

    The interaction of man with the ecosystem is a major factor causing environmental pollution and its attendant consequences such as climate change in our world today. Patents relating to nematodes' relevance in soil quality management and their significance as biomarkers in aquatic substrates were reviewed. Nematodes are useful in rapid, easy and inexpensive method for testing the toxicity of substance (e.g. aquatic substrates). This review paper sets out to examine and discuss the issue of soil pollution, functions of nematodes in soil and aquatic substrates as well as bio-indicators in soil health management in terrestrial ecology. The information used were on the basis of secondary sources from previous research. It is abundantly clear that the population dynamics of plant parasitic or free-living nematodes have useful potentials as biomonitor for soil health and other forms of environmental contamination through agricultural activities, industrial pollution and oil spillage, and the analysis of nematode community structure could be used as complementary information obtained from conventional soil testing approaches.

  8. Negative responses of Collembola in a forest soil (Alptal, Switzerland) under experimentally increased N deposition

    International Nuclear Information System (INIS)

    Xu Guoliang; Schleppi, Patrick; Li Maihe; Fu Shenglei

    2009-01-01

    The response of specific groups of organisms, like Collembola to atmospheric nitrogen (N) deposition is still scarcely known. We investigated the Collembola community in a subalpine forest (Alptal, Switzerland) as subjected for 12 years to an experimentally increased N deposition (+25 on top of ambient 12 kg N ha -1 year -1 ). In the 0-5 cm soil layer, there was a tendency of total Collembola densities to be lower in N-treated than in control plots. The density of Isotomiella minor, the most abundant species, was significantly reduced by the N addition. A tendency of lower Collembola group richness was observed in N-treated plots. The Density-Group index (d DG ) showed a significant reduction of community diversity, but the Shannon-Wiener index (H') was not significantly affected by the N addition. The Collembola community can be considered as a bioindicator of N inputs exceeding the biological needs, namely, soil N saturation. - Collembola community, which was significantly affected by a long-term N addition experiment, can be considered as a bioindicator of N saturation.

  9. Negative responses of Collembola in a forest soil (Alptal, Switzerland) under experimentally increased N deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xu Guoliang, E-mail: xugl@scbg.ac.c [Institute of Ecology, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650 (China); Schleppi, Patrick; Li Maihe [Swiss Federal Institute for Forest, Snow and Landscape Research, CH-8903 Birmensdorf (Switzerland); Fu Shenglei, E-mail: sfu@scib.ac.c [Institute of Ecology, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650 (China)

    2009-07-15

    The response of specific groups of organisms, like Collembola to atmospheric nitrogen (N) deposition is still scarcely known. We investigated the Collembola community in a subalpine forest (Alptal, Switzerland) as subjected for 12 years to an experimentally increased N deposition (+25 on top of ambient 12 kg N ha{sup -1} year{sup -1}). In the 0-5 cm soil layer, there was a tendency of total Collembola densities to be lower in N-treated than in control plots. The density of Isotomiella minor, the most abundant species, was significantly reduced by the N addition. A tendency of lower Collembola group richness was observed in N-treated plots. The Density-Group index (d{sub DG}) showed a significant reduction of community diversity, but the Shannon-Wiener index (H') was not significantly affected by the N addition. The Collembola community can be considered as a bioindicator of N inputs exceeding the biological needs, namely, soil N saturation. - Collembola community, which was significantly affected by a long-term N addition experiment, can be considered as a bioindicator of N saturation.

  10. The significance of soils and soil science towards realization of the United Nations Sustainable Development Goals

    Science.gov (United States)

    Keesstra, Saskia D.; Bouma, Johan; Wallinga, Jakob; Tittonell, Pablo; Smith, Pete; Cerdà, Artemi; Montanarella, Luca; Quinton, John N.; Pachepsky, Yakov; van der Putten, Wim H.; Bardgett, Richard D.; Moolenaar, Simon; Mol, Gerben; Jansen, Boris; Fresco, Louise O.

    2016-04-01

    In this forum paper we discuss how soil scientists can help to reach the recently adopted UN Sustainable Development Goals (SDGs) in the most effective manner. Soil science, as a land-related discipline, has important links to several of the SDGs, which are demonstrated through the functions of soils and the ecosystem services that are linked to those functions (see graphical abstract in the Supplement). We explore and discuss how soil scientists can rise to the challenge both internally, in terms of our procedures and practices, and externally, in terms of our relations with colleague scientists in other disciplines, diverse groups of stakeholders and the policy arena. To meet these goals we recommend the following steps to be taken by the soil science community as a whole: (i) embrace the UN SDGs, as they provide a platform that allows soil science to demonstrate its relevance for realizing a sustainable society by 2030; (ii) show the specific value of soil science: research should explicitly show how using modern soil information can improve the results of inter- and transdisciplinary studies on SDGs related to food security, water scarcity, climate change, biodiversity loss and health threats; (iii) take leadership in overarching system analysis of ecosystems, as soils and soil scientists have an integrated nature and this places soil scientists in a unique position; (iii) raise awareness of soil organic matter as a key attribute of soils to illustrate its importance for soil functions and ecosystem services; (iv) improve the transfer of knowledge through knowledge brokers with a soil background; (v) start at the basis: educational programmes are needed at all levels, starting in primary schools, and emphasizing practical, down-to-earth examples; (vi) facilitate communication with the policy arena by framing research in terms that resonate with politicians in terms of the policy cycle or by considering drivers, pressures and responses affecting impacts of land

  11. Microbial Community and Functional Structure Significantly Varied among Distinct Types of Paddy Soils But Responded Differently along Gradients of Soil Depth Layers

    Directory of Open Access Journals (Sweden)

    Ren Bai

    2017-05-01

    Full Text Available Paddy rice fields occupy broad agricultural area in China and cover diverse soil types. Microbial community in paddy soils is of great interest since many microorganisms are involved in soil functional processes. In the present study, Illumina Mi-Seq sequencing and functional gene array (GeoChip 4.2 techniques were combined to investigate soil microbial communities and functional gene patterns across the three soil types including an Inceptisol (Binhai, an Oxisol (Leizhou, and an Ultisol (Taoyuan along four profile depths (up to 70 cm in depth in mesocosm incubation columns. Detrended correspondence analysis revealed that distinctly differentiation in microbial community existed among soil types and profile depths, while the manifest variance in functional structure was only observed among soil types and two rice growth stages, but not across profile depths. Along the profile depth within each soil type, Acidobacteria, Chloroflexi, and Firmicutes increased whereas Cyanobacteria, β-proteobacteria, and Verrucomicrobia declined, suggesting their specific ecophysiological properties. Compared to bacterial community, the archaeal community showed a more contrasting pattern with the predominant groups within phyla Euryarchaeota, Thaumarchaeota, and Crenarchaeota largely varying among soil types and depths. Phylogenetic molecular ecological network (pMEN analysis further indicated that the pattern of bacterial and archaeal communities interactions changed with soil depth and the highest modularity of microbial community occurred in top soils, implying a relatively higher system resistance to environmental change compared to communities in deeper soil layers. Meanwhile, microbial communities had higher connectivity in deeper soils in comparison with upper soils, suggesting less microbial interaction in surface soils. Structure equation models were developed and the models indicated that pH was the most representative characteristics of soil type and

  12. Microbial Community and Functional Structure Significantly Varied among Distinct Types of Paddy Soils But Responded Differently along Gradients of Soil Depth Layers.

    Science.gov (United States)

    Bai, Ren; Wang, Jun-Tao; Deng, Ye; He, Ji-Zheng; Feng, Kai; Zhang, Li-Mei

    2017-01-01

    Paddy rice fields occupy broad agricultural area in China and cover diverse soil types. Microbial community in paddy soils is of great interest since many microorganisms are involved in soil functional processes. In the present study, Illumina Mi-Seq sequencing and functional gene array (GeoChip 4.2) techniques were combined to investigate soil microbial communities and functional gene patterns across the three soil types including an Inceptisol (Binhai), an Oxisol (Leizhou), and an Ultisol (Taoyuan) along four profile depths (up to 70 cm in depth) in mesocosm incubation columns. Detrended correspondence analysis revealed that distinctly differentiation in microbial community existed among soil types and profile depths, while the manifest variance in functional structure was only observed among soil types and two rice growth stages, but not across profile depths. Along the profile depth within each soil type, Acidobacteria , Chloroflexi , and Firmicutes increased whereas Cyanobacteria , β -proteobacteria , and Verrucomicrobia declined, suggesting their specific ecophysiological properties. Compared to bacterial community, the archaeal community showed a more contrasting pattern with the predominant groups within phyla Euryarchaeota , Thaumarchaeota , and Crenarchaeota largely varying among soil types and depths. Phylogenetic molecular ecological network (pMEN) analysis further indicated that the pattern of bacterial and archaeal communities interactions changed with soil depth and the highest modularity of microbial community occurred in top soils, implying a relatively higher system resistance to environmental change compared to communities in deeper soil layers. Meanwhile, microbial communities had higher connectivity in deeper soils in comparison with upper soils, suggesting less microbial interaction in surface soils. Structure equation models were developed and the models indicated that pH was the most representative characteristics of soil type and

  13. Management options to increase soil organic matter and nitrogen availability in cultivated drylands

    International Nuclear Information System (INIS)

    Grace, P.R.

    1998-01-01

    Cropping of dryland soils in marginal regions with an emphasis on economic rather than ecological sustainability has generally led to decline in soil organic matter reserves and hence nutrient availability. Outputs commonly exceed inputs, with degradation of soil structure, reduction in infiltration and increase in runoff. Biological productivity is severely affected, leading to a vicious cycle of events usually culminating in decreased N release, excessive soil loss and ultimately desertification. Reducing the incidence of bare fallow, increasing crop-residue retention, strategic N-fertilizer application and shifting to cereal-legume rotations (as opposed to monocultures) and intercropping can slow the spiral. Simulation models such as DSSAT and SOCRATES provide suitable and easy-to-use platforms to evaluate these management strategies in terms of soil organic matter accumulation and yield performance. Through the linkage of these models to global information systems and the use of spatial-characterization software to identify zones of similarity, it is now possible to examine the transportability and risk of a particular management strategy under a wide range of climatic and soil conditions. (author)

  14. Increased soil organic carbon stocks under agroforestry: A survey of six different sites in France

    Science.gov (United States)

    Cardinael, Rémi; Chevallier, Tiphaine; Cambou, Aurélie; Beral, Camille; Barthes, Bernard; Dupraz, Christian; Kouakoua, Ernest; Chenu, Claire

    2017-04-01

    Introduction: Agroforestry systems are land use management systems in which trees are grown in combination with crops or pasture in the same field. In silvoarable systems, trees are intercropped with arable crops, and in silvopastoral systems trees are combined with pasture for livestock. These systems may produce forage and timber as well as providing ecosystem services such as climate change mitigation. Carbon (C) is stored in the aboveground and belowground biomass of the trees, and the transfer of organic matter from the trees to the soil can increase soil organic carbon (SOC) stocks. Few studies have assessed the impact of agroforestry systems on carbon storage in soils in temperate climates, as most have been undertaken in tropical regions. Methods: This study assessed five silvoarable systems and one silvopastoral system in France. All sites had an agroforestry system with an adjacent, purely agricultural control plot. The land use management in the inter-rows in the agroforestry systems and in the control plots were identical. The age of the study sites ranged from 6 to 41 years after tree planting. Depending on the type of soil, the sampling depth ranged from 20 to 100 cm and SOC stocks were assessed using equivalent soil masses. The aboveground biomass of the trees was also measured at all sites. Results: In the silvoarable systems, the mean organic carbon stock accumulation rate in the soil was 0.24 (0.09-0.46) Mg C ha-1 yr-1 at a depth of 30 cm and 0.65 (0.004-1.85) Mg C ha-1 yr-1 in the tree biomass. Increased SOC stocks were also found in deeper soil layers at two silvoarable sites. Young plantations stored additional SOC but mainly in the soil under the rows of trees, possibly as a result of the herbaceous vegetation growing in the rows. At the silvopastoral site, the SOC stock was significantly greater at a depth of 30-50 cm than in the control. Overall, this study showed the potential of agroforestry systems to store C in both soil and biomass in

  15. Toxicological significance of soil ingestion by wild and domestic animals

    Science.gov (United States)

    Beyer, W. Nelson; Fries, George F.; Hoffman, David J.; Rattner, Barnett A.; Burton, G. Allen; Cairns, John

    2003-01-01

    Most wild and domestic animals ingest some soil or sediment, and some species may routinely, or under special circumstances, ingest considerable amounts. Ingested soil supplies nutrients, exposes animals to parasites and pathogens, and may play a role in developing immune systems.1 Soil ingestion is also sometimes the principal route of exposure to various environmental contaminants.2-7 Ingestion of soil and earthy material is defined as geophagy and may be either intentional or unintentional, occurring as an animal eats or grooms.

  16. Soil nitrate reducing processes - drivers, mechanisms for spatial variation, and significance for nitrous oxide production.

    Science.gov (United States)

    Giles, Madeline; Morley, Nicholas; Baggs, Elizabeth M; Daniell, Tim J

    2012-01-01

    The microbial processes of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) are two important nitrate reducing mechanisms in soil, which are responsible for the loss of nitrate ([Formula: see text]) and production of the potent greenhouse gas, nitrous oxide (N(2)O). A number of factors are known to control these processes, including O(2) concentrations and moisture content, N, C, pH, and the size and community structure of nitrate reducing organisms responsible for the processes. There is an increasing understanding associated with many of these controls on flux through the nitrogen cycle in soil systems. However, there remains uncertainty about how the nitrate reducing communities are linked to environmental variables and the flux of products from these processes. The high spatial variability of environmental controls and microbial communities across small sub centimeter areas of soil may prove to be critical in determining why an understanding of the links between biotic and abiotic controls has proved elusive. This spatial effect is often overlooked as a driver of nitrate reducing processes. An increased knowledge of the effects of spatial heterogeneity in soil on nitrate reduction processes will be fundamental in understanding the drivers, location, and potential for N(2)O production from soils.

  17. Aspen increase soil moisture, nutrients, organic matter and respiration in Rocky Mountain forest communities.

    Science.gov (United States)

    Buck, Joshua R; St Clair, Samuel B

    2012-01-01

    Development and change in forest communities are strongly influenced by plant-soil interactions. The primary objective of this paper was to identify how forest soil characteristics vary along gradients of forest community composition in aspen-conifer forests to better understand the relationship between forest vegetation characteristics and soil processes. The study was conducted on the Fishlake National Forest, Utah, USA. Soil measurements were collected in adjacent forest stands that were characterized as aspen dominated, mixed, conifer dominated or open meadow, which includes the range of vegetation conditions that exist in seral aspen forests. Soil chemistry, moisture content, respiration, and temperature were measured. There was a consistent trend in which aspen stands demonstrated higher mean soil nutrient concentrations than mixed and conifer dominated stands and meadows. Specifically, total N, NO(3) and NH(4) were nearly two-fold higher in soil underneath aspen dominated stands. Soil moisture was significantly higher in aspen stands and meadows in early summer but converged to similar levels as those found in mixed and conifer dominated stands in late summer. Soil respiration was significantly higher in aspen stands than conifer stands or meadows throughout the summer. These results suggest that changes in disturbance regimes or climate scenarios that favor conifer expansion or loss of aspen will decrease soil resource availability, which is likely to have important feedbacks on plant community development.

  18. A possible mechanism relating increased soil temperature to forest decline

    International Nuclear Information System (INIS)

    Tomlinson, G.H.

    1993-01-01

    Nutrient cations are removed from the soil by uptake in biomass, and by leaching as a result of soil acidification. Such acidification results from acid deposition and/or from HNO 3 formed by mineralization and nitrification of humus, when at a rate in excess of the tree's nutritional requirements. This has been found to occur during and following periods of increased temperature and reduced rainfall. The cumulative loss of either Ca 2+ , Mg 2+ or K + by one or more of these processes, if greater than the amount released from the specific minerals in that soil, leads to nutrient deficiency, fine root mortality, poor growth, and eventually to die-back. Trees growing in soils derived from specific minerals in which there is a strong imbalance in the elements from which the exchangeable nutrients are formed, are vulnerable to nutrient deficiency. This paper discusses the relevance of earlier studies, when considered in relation to more recent findings. In Hawaii there have been frequent periods of increased temperature and drought resulting from the El Nino Southern Oscillation. This fact, when considered in relation to the relatively low K content, and its imbalance with Ca and Mg in the lava and volcanic ash on which the trees have grown, could result in K deficiency in the declining ohia trees. It is possible that the unusual periods of increased temperature and drought which have occurred in certain other localized areas may have led to the decline symptoms recently observed. In view of the threat of global warming, this possibility should be investigated. 39 refs., 3 figs., 2 tabs

  19. Increasing cotton stand establishment in soils prone to soil crusting

    Science.gov (United States)

    Many factors can contribute to poor cotton stand establishment, and cotton is notorious for its weak seedling vigor. Soil crusting can be a major factor hindering cotton seedling emergence in many of the cotton production regions of the US and the world. Crusting is mainly an issue in silty soils ...

  20. Elevated CO2 and temperature increase soil C losses from a soybean-maize ecosystem.

    Science.gov (United States)

    Black, Christopher K; Davis, Sarah C; Hudiburg, Tara W; Bernacchi, Carl J; DeLucia, Evan H

    2017-01-01

    Warming temperatures and increasing CO 2 are likely to have large effects on the amount of carbon stored in soil, but predictions of these effects are poorly constrained. We elevated temperature (canopy: +2.8 °C; soil growing season: +1.8 °C; soil fallow: +2.3 °C) for 3 years within the 9th-11th years of an elevated CO 2 (+200 ppm) experiment on a maize-soybean agroecosystem, measured respiration by roots and soil microbes, and then used a process-based ecosystem model (DayCent) to simulate the decadal effects of warming and CO 2 enrichment on soil C. Both heating and elevated CO 2 increased respiration from soil microbes by ~20%, but heating reduced respiration from roots and rhizosphere by ~25%. The effects were additive, with no heat × CO 2 interactions. Particulate organic matter and total soil C declined over time in all treatments and were lower in elevated CO 2 plots than in ambient plots, but did not differ between heat treatments. We speculate that these declines indicate a priming effect, with increased C inputs under elevated CO 2 fueling a loss of old soil carbon. Model simulations of heated plots agreed with our observations and predicted loss of ~15% of soil organic C after 100 years of heating, but simulations of elevated CO 2 failed to predict the observed C losses and instead predicted a ~4% gain in soil organic C under any heating conditions. Despite model uncertainty, our empirical results suggest that combined, elevated CO 2 and temperature will lead to long-term declines in the amount of carbon stored in agricultural soils. © 2016 John Wiley & Sons Ltd.

  1. Jerusalem artichoke decreased salt content and increased diversity of bacterial communities in the rhizosphere soil in the coastal saline zone

    Science.gov (United States)

    Shao, Tianyun; Li, Niu; Cheng, Yongwen; Long, Xiaohua; Shao, Hongbo; Zed, Rengel

    2017-04-01

    Soil salinity is one of the main environmental constraints that restrict plant growth and agricultural productivity; however, utilization of salt-affected land can bring substantial benefits. This study used an in-situ remediation method by planting Jerusalem artichoke in naturally occurring saline alkali soils with different salinity (high salinity (H, >4.0 g•salt kg-1 soil), moderate salinity (M, 2.0-4.0 g•salt kg-1 soil) and low salinity (L, 1.0-2.0 g•salt kg-1 soil) in the coastal saline zone in southeast China in comparison with the respective controls without Jerusalem artichoke planting (undisturbed soil). Soil pH and salinity increased sequentially from the rhizosphere to the bulk soil and the unplanted controls. The activity of neutral phosphatase and invertase decreased in the order L > M > H, whereas that of catalase was reverse. The minimum content of calcite, muscovite and quartz, and maximum content of chlorite and albite, were found in the control soils. Planting of Jerusalem artichoke enhanced bacterial microflora in saline alkali soil. Proteobacteria, Acidobacteria, Actinobacteria and Bacteroidetes were the dominant phyla in all samples, accounting for more than 80% of the reads. The number of Operational Taxonomic Units (OTU) in the rhizosphere soil was, respectively, 1.27, 1.02 and 1.25 times higher compared with the bulk soil, suggesting that Jerusalem artichoke played a significant role in increasing abundance and diversity of soil microbial populations. The study showed that Jerusalem artichoke could be used to improve saline alkali soil by enriching bacterial communities, enhancing the activity of phosphatase and invertase, and decreasing soil salinity.

  2. Elevated atmospheric CO2 increases microbial growth rates and enzymes activity in soil

    Science.gov (United States)

    Blagodatskaya, Evgenia; Blagodatsky, Sergey; Dorodnikov, Maxim; Kuzyakov, Yakov

    2010-05-01

    Increasing the belowground translocation of assimilated carbon by plants grown under elevated CO2 can cause a shift in the structure and activity of the microbial community responsible for the turnover of organic matter in soil. We investigated the long-term effect of elevated CO2 in the atmosphere on microbial biomass and specific growth rates in root-free and rhizosphere soil. The experiments were conducted under two free air carbon dioxide enrichment (FACE) systems: in Hohenheim and Braunschweig, as well as in the intensively managed forest mesocosm of the Biosphere 2 Laboratory (B2L) in Oracle, AZ. Specific microbial growth rates (μ) were determined using the substrate-induced respiration response after glucose and/or yeast extract addition to the soil. We evaluated the effect of elevated CO2 on b-glucosidase, chitinase, phosphatase, and sulfatase to estimate the potential enzyme activity after soil amendment with glucose and nutrients. For B2L and both FACE systems, up to 58% higher μ were observed under elevated vs. ambient CO2, depending on site, plant species and N fertilization. The μ-values increased linearly with atmospheric CO2 concentration at all three sites. The effect of elevated CO2 on rhizosphere microorganisms was plant dependent and increased for: Brassica napus=Triticum aestivumyeast extract then for those growing on glucose, i.e. the effect of elevated CO2 was smoothed on rich vs. simple substrate. So, the r/K strategies ratio can be better revealed by studying growth on simple (glucose) than on rich substrate mixtures (yeast extract). After adding glucose, enzyme activities under elevated CO2 were 1.2-1.9-fold higher than under ambient CO2. This indicates the increased activity of microorganisms, which leads to accelerated C turnover in soil under elevated CO2. Our results clearly showed that the functional characteristics of the soil microbial community (i.e. specific growth rates and enzymes activity) rather than total microbial biomass

  3. Carbon storage potential increases with increasing ratio of C4 to C3 grass cover and soil productivity in restored tallgrass prairies.

    Science.gov (United States)

    Spiesman, Brian J; Kummel, Herika; Jackson, Randall D

    2018-02-01

    Long-term soil carbon (C) storage is essential for reducing CO 2 in the atmosphere. Converting unproductive and environmentally sensitive agricultural lands to grasslands for bioenergy production may enhance C storage. However, a better understanding of the interacting effects of grass functional composition (i.e., relative abundance of C 4 and C 3 grass cover) and soil productivity on C storage will help guide sustainable grassland management. Our objective was to examine the relationship between grass functional composition and potential C storage and how it varies with potential soil productivity. We estimated C inputs from above- and belowground net primary productivity (ANPP and BNPP), and heterotrophic respiration (R H ) to calculate net ecosystem production (NEP), a measure of potential soil C storage, in grassland plots of relatively high- and low-productivity soils spanning a gradient in the ratio of C 4 to C 3 grass cover (C 4 :C 3 ). NEP increased with increasing C 4 :C 3 , but only in potentially productive soils. The positive relationship likely stemmed from increased ANPP, rather than BNPP, which was possibly related to efficient resource-use and physiological/anatomical advantages of C 4 plants. R H was negatively correlated with C 4 :C 3 , possibly because of changes in microclimate or plant-microbe interactions. It is possible that in potentially productive soils, C storage can be enhanced by favoring C 4 over C 3 grasses through increased ANPP and BNPP and reduced R H . Results also suggest that potential C storage gains from C 4 productivity would not be undermined by a corresponding increase in R H .

  4. Fire increases the risk of higher soil N2O emissions from Mediterranean Macchia ecosystems

    DEFF Research Database (Denmark)

    Karhu, Kristiina; Dannenmann, M.; Kitzler, B.

    2015-01-01

    on climate change. However, the potential importance of indirect GHG emissions due to changes in soil biological and chemical properties after fire is less well known. Increased soil mineral nitrogen (N) concentrations after fire pose a risk for increased emissions of gaseous N, but studies on the post......-fire N2O production and soil N turnover rates (mineralization, nitrification, microbial immobilization, denitrification) are still rare. We determined N2O production, rates of N turnover and pathways for N2O production from the soil of burned and unburned plots of a Macchia shrubland in central Spain...... using a 15N labelling approach. Measurements were initiated before the controlled burning and continued for up to half a year after fire. Fire markedly increased the risk of N2O emissions from soil through denitrification (N2O production rate was 3 to ≈30 times higher in burned soils compared to control...

  5. Salinity altered root distribution and increased diversity of bacterial communities in the rhizosphere soil of Jerusalem artichoke

    Science.gov (United States)

    Yang, Hui; Hu, Jinxiang; Long, Xiaohua; Liu, Zhaopu; Rengel, Zed

    2016-02-01

    The interaction between roots and bacterial communities in halophytic species is poorly understood. Here, we used Jerusalem artichoke cultivar Nanyu 1 (NY-1) to characterise root distribution patterns and determine diversity and abundance of bacteria in the rhizosphere soil under variable salinity. Root growth was not inhibited within the salinity range 1.2 to 1.9 g salt/kg, but roots were mainly confined to 0-20 cm soil layer vertically and 0-30 cm horizontally from the plant centre. Root concentrations of K+, Na+, Mg2+ and particularly Ca2+ were relatively high under salinity stress. High salinity stress decreased soil invertase and catalase activity. Using a next-generation, Illumina-based sequencing approach, we determined higher diversity of bacteria in the rhizosphere soil at high than low salinity. More than 15,500 valid reads were obtained, and Proteobacteria, Acidobacteria, Bacteroidetes and Actinobacteria predominated in all samples, accounting for >80% of the reads. On a genus level, 636 genera were common to the low and high salinity treatments at 0-5 cm and 5-10 cm depth. The abundance of Steroidobacter and Sphingomonas was significantly decreased by increasing salinity. Higher Shannon and Chao 1 indices with increasing severity of salt stress indicated that high salt stress increased diversity in the bacterial communities.

  6. The Significance of Land Cover Delineation on Soil Erosion Assessment.

    Science.gov (United States)

    Efthimiou, Nikolaos; Psomiadis, Emmanouil

    2018-04-25

    The study aims to evaluate the significance of land cover delineation on soil erosion assessment. To that end, RUSLE (Revised Universal Soil Loss Equation) was implemented at the Upper Acheloos River catchment, Western Central Greece, annually and multi-annually for the period 1965-92. The model estimates soil erosion as the linear product of six factors (R, K, LS, C, and P) considering the catchment's climatic, pedological, topographic, land cover, and anthropogenic characteristics, respectively. The C factor was estimated using six alternative land use delineations of different resolution, namely the CORINE Land Cover (CLC) project (2000, 2012 versions) (1:100,000), a land use map conducted by the Greek National Agricultural Research Foundation (NAGREF) (1:20,000), a land use map conducted by the Greek Payment and Control Agency for Guidance and Guarantee Community Aid (PCAGGCA) (1:5,000), and the Landsat 8 16-day Normalized Difference Vegetation Index (NDVI) dataset (30 m/pixel) (two approximations) based on remote sensing data (satellite image acquired on 07/09/2016) (1:40,000). Since all other factors remain unchanged per each RUSLE application, the differences among the yielded results are attributed to the C factor (thus the land cover pattern) variations. Validation was made considering the convergence between simulated (modeled) and observed sediment yield. The latter was estimated based on field measurements conducted by the Greek PPC (Public Power Corporation). The model performed best at both time scales using the Landsat 8 (Eq. 13) dataset, characterized by a detailed resolution and a satisfactory categorization, allowing the identification of the most susceptible to erosion areas.

  7. Composted Cattle Manure Increases Microbial Activity and Soil Fertility More Than Composted Swine Manure in a Submerged Rice Paddy

    Directory of Open Access Journals (Sweden)

    Suvendu Das

    2017-09-01

    Full Text Available Livestock waste composts with minimum inorganic fertilizer as a soil amendment in low-input intensive farming are a feasible agricultural practice to improve soil fertility and productivity and to mitigate soil degradation. The key benefits of the practice rely on the activities of soil microorganisms. However, the role of different livestock composts [composted cattle manure (CCM vs. composted swine manure (CSM] on soil microbes, their activities and the overall impact on soil fertility and productivity in a flooded paddy remains elusive. This study compares the effectiveness of CCM and CSM amendment on bacterial communities, activities, nutrient availability, and crop yield in a flooded rice cropping system. We used deep 16S amplicon sequencing and soil enzyme activities to decipher bacterial communities and activities, respectively. Both CCM and CSM amendment significantly increased soil pH, nutrient availability (C, N, and P, microbial biomass, soil enzyme activities indicative for C and N cycles, aboveground plant biomass and grain yield. And the increase in above-mentioned parameters was more prominent in the CCM treatment compared to the CSM treatment. The CCM amendment increased species richness and stimulated copiotrophic microbial groups (Alphaproteobacteria, Betaproteobacteria, and Firmicutes which are often involved in degradation of complex organic compounds. Moreover, some dominant species (e.g., Azospirillum zeae, Azospirillum halopraeferens, Azospirillum rugosum, Clostridium alkalicellulosi, Clostridium caenicola, Clostridium termitidis, Clostridium cellulolyticum, Magnetospirillum magnetotacticum, Pleomorphomonas oryzae, Variovorax boronicumulans, Pseudomonas xanthomarina, Pseudomonas stutzeri, and Bacillus niacini which have key roles in plant growth promotion and/or lignocellulose degradation were enhanced under CCM treatment compared to CSM treatment. Multivariate analysis revealed that soil pH and available carbon (C and

  8. Isolation of a significant fraction of non-phototroph diversity from a desert Biological Soil Crust

    Directory of Open Access Journals (Sweden)

    Ulisses eNunes da Rocha

    2015-04-01

    Full Text Available Biological Soil Crusts (BSCs are organosedimentary assemblages comprised of microbes and minerals in topsoil of terrestrial environments. BSCs strongly impact soil quality in dryland ecosystems (e.g., soil structure and nutrient yields due to pioneer species such as Microcoleus vaginatus; phototrophs that produce filaments that bind the soil together, and support an array of heterotrophic microorganisms. These microorganisms in turn contribute to soil stability and biogeochemistry of BSCs. Non-cyanobacterial populations of BSCs are less well known than cyanobacterial populations. Therefore, we attempted to isolate a broad range of numerically significant and phylogenetically representative BSC aerobic heterotrophs. Combining simple pre-treatments (hydration of BSCs under dark and light and isolation strategies (media with varying nutrient availability and protection from oxidative stress we recovered 402 bacterial and one fungal isolate in axenic culture, which comprised 116 phylotypes (at 97% 16S rRNA gene sequence homology, 115 bacterial and one fungal. Each medium enriched a mostly distinct subset of phylotypes, and cultivated phylotypes varied due to the BSC pre-treatment. The fraction of the total phylotype diversity isolated, weighted by relative abundance in the community, was determined by the overlap between isolate sequences and OTUs reconstructed from metagenome or metatranscriptome reads. Together, more than 8% of relative abundance of OTUs in the metagenome was represented by our isolates, a cultivation efficiency much larger than typically expected from most soils. We conclude that simple cultivation procedures combined with specific pre-treatment of samples afford a significant reduction in the culturability gap, enabling physiological and metabolic assays that rely on ecologically relevant axenic cultures.

  9. Harnessing the soil microbiome for increased drought resistance

    Science.gov (United States)

    Dr. Manter is a Research Soil Scientist in the Soil Management and Sugar Beet Research Unit (SMSBRU) of the USDA-Agricultural Research Service in Fort Collins, Colorado. His research examines soil biology and plant-microbial interactions aimed at optimizing soil health. Research emphasis is on dev...

  10. Gas revenue increasingly significant

    International Nuclear Information System (INIS)

    Megill, R.E.

    1991-01-01

    This paper briefly describes the wellhead prices of natural gas compared to crude oil over the past 70 years. Although natural gas prices have never reached price parity with crude oil, the relative value of a gas BTU has been increasing. It is one of the reasons that the total amount of money coming from natural gas wells is becoming more significant. From 1920 to 1955 the revenue at the wellhead for natural gas was only about 10% of the money received by producers. Most of the money needed for exploration, development, and production came from crude oil. At present, however, over 40% of the money from the upstream portion of the petroleum industry is from natural gas. As a result, in a few short years natural gas may become 50% of the money revenues generated from wellhead production facilities

  11. National monitoring study in Denmark finds increased and critical levels of copper and zinc in arable soils fertilized with pig slurry.

    Science.gov (United States)

    Jensen, John; Larsen, Martin Mørk; Bak, Jesper

    2016-07-01

    The increasing consumption of copper and zinc in modern farming is linked to their documented benefit as growth promoting agents and usefulness for controlling diarrhoea. Copper and zinc are inert and non-degradable in the slurry and the environment and thereby introducing new challenges and concern. Therefore, a follow-up to pervious national soil monitoring programs on heavy metals was initiated in 2014 with special focus on the historical trends in soil concentrations of copper and zinc in Danish arable soils. Hereby it is possible to analyse trends for a 28 year period. Data shows that: 1) Amendment of soils with pig slurry has led to a significant increase in soil concentrations of copper and zinc, especially in the latest monitoring period from 1998 to 2014; 2) Predicted no-effect concentrations for soil dwelling species published by the European Union is exceeded for zinc in 45% of all soil samples, with the highest proportion on sandy soils; 3) The current use of zinc and copper in pig production may lead to leaching of metals, especially zinc, from fields fertilized with pig slurry in concentrations that may pose a risk to aquatic species. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. [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.

  13. Amelioration of acidic soil increases the toxicity of the weak base carbendazim to the earthworm Eisenia fetida.

    Science.gov (United States)

    Liu, Kailin; Wang, Shaoyun; Luo, Kun; Liu, Xiangying; Yu, Yunlong

    2013-12-01

    Ameliorating acidic soils is a common practice and may affect the bioavailability of an ionizable organic pollutant to organisms. The toxicity of the weak base carbendazim to the earthworm (Eisenia fetida) was studied in an acidic soil (pH-H₂O, 4.6) and in the ameliorated soil (pH-H₂O, 7.5). The results indicated that the median lethal concentration of carbendazim for E. fetida decreased from 21.8 mg/kg in acidic soil to 7.35 mg/kg in the ameliorated soil. To understand why the amelioration increased carbendazim toxicity to the earthworm, the authors measured the carbendazim concentrations in the soil porewater. The authors found increased carbendazim concentrations in porewater, resulting in increased toxicity of carbendazim to earthworms. The increased pore concentrations result from decreased adsorption because of the effects of pH and calcium ions. © 2013 SETAC.

  14. Evaluation and development of soil values for the pathway 'soil to plant'. Significance of mercury evaporation for the burden of plants

    International Nuclear Information System (INIS)

    Gaeth, S.; Schlueter, K.

    1998-05-01

    In cooperation with the Ad-hoc working group 'Transfer of heavy metals from soil to plant' of the Laenderarbeitsgemeinschaft Bodenschutz (LABO) the significance of mercury evaporation for the deduction of threshold values in respect of the impact via the pathway soil to plant was investigated. Mercury contamination of food- and feeding stuff plants was examined with special emphasis. For these purposes a lab experiment including three different soils with varying initial mercury load (background level, geogenic and anthropogenic contamination) and two different plant species (parsely and spinach) was carried out under defined conditions in closed lysimeters. Mercury uptake via the roots was minimised since the plants grew in isolated customary substrate which showed a low concentration of mercury. Thus, only the surrounding soil evaporated mercury. The concentrations of mercury in the plants in the background level treatment (0.1 mg Hg/kg dry soil) were 0.15 mg/kg dry matter (spinach) and 0.44 mg/kg dry matter (parsely). The treatment with anthropogenic contaminated soil (111 mg Hg/kg dry soil) resulted in concentrations in the two plants of 2.0 and 2.6 mg/kg dry matter, respectively. A comparable order of magnitude was achieved in the geogenic contaminated treatment (34 mg Hg/kg dry soil) with 2.1 mg/kg dry matter. Experiments conducted with radioactive 203 Hg showed in each case recoveries of 20 to 34% in the leaves regarding the evaporated Hg-tracer. Also in the stem and in the roots Hg-tracer could be detected, indicating a translocation within the plant from leaf to root. By means of a comprehensive literature study the state of the art for Hg-evaporation and Hg-uptake of plants was compiled. Comparing the experimental results with data derived from literature, the Hg-concentrations found are confirmed by results of other authors. (orig.) [de

  15. Soil biogeochemistry properties vary between two boreal forest ecosystems in Quebec: significant differences in soil carbon, available nutrients and iron and aluminium crystallinity

    Science.gov (United States)

    Bastianelli, Carole; Ali, Adam A.; Beguin, Julien; Bergeron, Yves; Grondin, Pierre; Hély, Christelle; Paré, David

    2017-04-01

    At the northernmost extent of the managed forest in Quebec, the boreal forest is currently undergoing an ecological transition from closed-canopy black spruce-moss forests towards open-canopy lichen woodlands, which spread southward. Our study aim was to determine whether this shift could impact soil properties on top of its repercussions on forest productivity or carbon storage. We studied the soil biogeochemical composition of three pedological layers in moss forests (MF) and lichen woodlands (LW) north of the Manicouagan crater in Quebec. The humus layer (FH horizons) was significantly thicker and held more carbon, nitrogen and exchangeable Ca and Mg in MF plots than in LW plots. When considering mineral horizons, we found that the deep C horizon had a very close composition in both ecosystem plots, suggesting that the parent material was of similar geochemical nature. This was expected as all selected sites developed from glacial deposit. Multivariate analysis of surficial mineral B horizon showed however that LW B horizon displayed higher concentrations of Al and Fe oxides than MF B horizon, particularly for inorganic amorphous forms. Conversely, main exchangeable base cations (Ca, Mg) were higher in B horizon of MF than that of LW. Ecosystem types explained much of the variations in the B horizon geochemical composition. We thus suggest that the differences observed in the geochemical composition of the B horizon have a biological origin rather than a mineralogical origin. We also showed that total net stocks of carbon stored in MF soils were three times higher than in LW soils (FH + B horizons, roots apart). Altogether, we suggest that variations in soil properties between MF and LW are linked to a cascade of events involving the impacts of natural disturbances such as wildfires on forest regeneration that determines the of vegetation structure (stand density) and composition (ground cover type) and their subsequent consequences on soil environmental

  16. Effects of warming on uptake and translocation of cadmium (Cd) and copper (Cu) in a contaminated soil-rice system under Free Air Temperature Increase (FATI).

    Science.gov (United States)

    Ge, Li-Qiang; Cang, Long; Liu, Hui; Zhou, Dong-Mei

    2016-07-01

    Global warming has received growing attentions about its potential threats to human in recent, however little is known about its effects on transfer of heavy metals in agro-ecosystem, especially for Cd in rice. Pot experiments were conducted to evaluate Cd/Cu translocation in a contaminated soil-rice system under Free Air Temperature Increase (FATI). The results showed that warming gradually decreased soil porewater pH and increased water-soluble Cd/Cu concentration, reduced formation of iron plaque on root surface, and thus significantly increased total uptake of Cd/Cu by rice. Subsequently, warming significantly promoted Cd translocation from root to shoot, and increased Cd distribution percentage in shoot, while Cu was not significantly affected. Enhanced Cd uptake and translocation synergistically resulted in higher rice grain contamination with increasing concentration from 0.27 to 0.65 and 0.14-0.40 mg kg(-1) for Indica and Japonica rice, respectively. However increase of Cu in brown grain was only attributed to its uptake enhancement under warming. Our study provides a new understanding about the food production insecurity of heavy metal contaminated soil under the future global warming. Copyright © 2016. Published by Elsevier Ltd.

  17. Soil nitrate reducing processes – drivers, mechanisms for spatial variation, and significance for nitrous oxide production

    Science.gov (United States)

    Giles, Madeline; Morley, Nicholas; Baggs, Elizabeth M.; Daniell, Tim J.

    2012-01-01

    The microbial processes of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) are two important nitrate reducing mechanisms in soil, which are responsible for the loss of nitrate (NO3−) and production of the potent greenhouse gas, nitrous oxide (N2O). A number of factors are known to control these processes, including O2 concentrations and moisture content, N, C, pH, and the size and community structure of nitrate reducing organisms responsible for the processes. There is an increasing understanding associated with many of these controls on flux through the nitrogen cycle in soil systems. However, there remains uncertainty about how the nitrate reducing communities are linked to environmental variables and the flux of products from these processes. The high spatial variability of environmental controls and microbial communities across small sub centimeter areas of soil may prove to be critical in determining why an understanding of the links between biotic and abiotic controls has proved elusive. This spatial effect is often overlooked as a driver of nitrate reducing processes. An increased knowledge of the effects of spatial heterogeneity in soil on nitrate reduction processes will be fundamental in understanding the drivers, location, and potential for N2O production from soils. PMID:23264770

  18. Soil nitrate reducing processes – drivers, mechanisms for spatial variation and significance for nitrous oxide production

    Directory of Open Access Journals (Sweden)

    Madeline Eleanore Giles

    2012-12-01

    Full Text Available The microbial processes of denitrification and dissimilatory nitrate reduction to ammonium (DNRA are two important nitrate reducing mechanisms in soil, which are responsible for the loss of nitrate (NO3-¬ and production of the potent greenhouse gas, nitrous oxide (N2O. A number of factors are known to control these processes, including O2 concentrations and moisture content, N, C, pH and the size and community structure of nitrate reducing organisms responsible for the processes. There is an increasing understanding associated with many of these controls on flux through the nitrogen cycle in soil systems. However, there remains uncertainty about how the nitrate reducing communities are linked to environmental variables and the flux of products from these processes. The high spatial variability of environmental controls and microbial communities across small sub cm areas of soil may prove to be critical in determining why an understanding of the links between biotic and abiotic controls has proved elusive. This spatial effect is often overlooked as a driver of nitrate reducing processes. An increased knowledge of the effects of spatial heterogeneity in soil on nitrate reduction processes will be fundamental in understanding the drivers, location and potential for N2O production from soils.

  19. Pinon-juniper reduction increases soil water availability of the resource growth pool

    Science.gov (United States)

    Bruce A. Roundy; Kert Young; Nathan Cline; April Hulet; Richard F. Miller; Robin J. Tausch; Jeanne C. Chambers; Ben Rau

    2014-01-01

    Managers reduce piñon (Pinus spp.) and juniper (Juniperus spp.) trees that are encroaching on sagebrush (Artemisia spp.) communities to lower fuel loads and increase cover of desirable understory species. All plant species in these communities depend on soil water held at > −1.5 MPa matric potential in the upper 0.3 m of soil for nutrient...

  20. Nitrogen Fertilization Increases Cottonwood Growth on Old-Field Soil

    Science.gov (United States)

    B. G. Blackmon; E. H. White

    1972-01-01

    Nitrogen (150 lb ./acre as NH4N03 ) applied to a 6-year-old eastern cottonwood plantation in an old field on Commerce silt loam soil increased diameter, basal area, and volume growth by 200 percent over untreated controls. The plantation did not respond to 100 pounds P per acre from concentrated superphosphate.

  1. Revegetation of the riparian zone of the Three Gorges Dam Reservoir leads to increased soil bacterial diversity.

    Science.gov (United States)

    Ren, Qingshui; Li, Changxiao; Yang, Wenhang; Song, Hong; Ma, Peng; Wang, Chaoying; Schneider, Rebecca L; Morreale, Stephen J

    2018-06-06

    As one of the most active components in soil, bacteria can affect soil physicochemical properties, its biological characteristics, and even its quality and health. We characterized dynamics of the soil bacterial diversity in planted (with Taxodium distichum) and unplanted soil in the riparian zone of the Three Gorges Dam Reservoir (TGDR), in southwestern China, in order to accurately quantify the changes in long-term soil bacterial community structure after revegetation. Measurements were taken annually in situ in the TGDR over the course of 5 years, from 2012 to 2016. Soil chemical properties and bacterial diversity were analyzed in both the planted and unplanted soil. After revegetation, the soil chemical properties in planted soil were significantly different than in unplanted soil. The effects of treatment, time, and the interaction of both time and treatment had significant impacts on most diversity indices. Specifically, the bacterial community diversity indices in planted soil were significantly higher and more stable than that in unplanted soil. The correlation analyses indicated that the diversity indices correlated with the pH value, organic matter, and soil available nutrients. After revegetation in the riparian zone of the TGDR, the soil quality and health is closely related to the observed bacterial diversity, and a higher bacterial diversity avails the maintenance of soil functionality. Thus, more reforestation should be carried out in the riparian zone of the TGDR, so as to effectively mitigate the negative ecological impacts of the dam. Vegetating the reservoir banks with Taxodium distichum proved successful, but planting mixed stands of native tree species could promote even higher riparian soil biodiversity and improved levels of ecosystem functioning within the TGDR.

  2. Buried straw layer and plastic mulching increase microlfora diversity in salinized soil

    Institute of Scientific and Technical Information of China (English)

    LI Yu-yi; PANG Huan-cheng; HAN Xiu-fang; YAN Shou-wei; ZHAO Yong-gan; WANG Jing; ZHAI Zhen; ZHANG Jian-li

    2016-01-01

    Salt stress has been increasingly constraining crop productivity in arid lands of the world. In our recent study, salt stress was aleviated and crop productivity was improved remarkably by straw layer burial plus plastic iflm mulching in a saline soil. However, its impact on the microlfora diversity is not wel documented. Field micro-plot experiments were conducted from 2010 to 2011 using four tilage methods: (i) deep tilage with plastic iflm mulching (CK), (i) straw layer burial at 40 cm (S), (ii) straw layer burial plus surface soil mulching with straw material (S+S), and (iv) plastic iflm mulching plus buried straw layer (P+S). Culturable microbes and predominant bacterial communities were studied; based on 16S rDNA, bacterial com-munity structure and abundance were characterized using denaturing gradient gel electrophoresis (DGGE) and polymerase chain reaction (PCR). Results showed that P+S was the most favorable for culturable bacteria, actinomyces and fungi and induced the most diverse genera of bacteria compared to other tilage methods. Soil temperature had signiifcant positive correlations with the number of bacteria, actinomyces and fungi (P<0.01). However, soil water was poorly correlated with any of the microbes. Salt content had a signiifcant negative correlation with the number of microbers, especialy for bacteria and fungi (P<0.01). DGGE analysis showed that the P+S exhibited the highest diversity of bacteria with 20 visible bands folowed by S+S, S and CK. Moreover, P+S had the highest similarity (68%) of bacterial communities with CK. The major bacterial genera in al soil samples wereFirmicutes,Proteobacteria andActinobacteria. Given the considerable increase in microbial growth, the combined use of straw layer burial and plastic iflm mulching could be a practical option for aleviating salt stress effects on soil microbial community and thereby improving crop production in arid saline soils.

  3. Initial Soil Organic Matter Content Influences the Storage and Turnover of Litter-, Root- and Soil Carbon in Grasslands

    Science.gov (United States)

    Liu, L.; Xu, S.; Li, P.; Sayer, E. J.

    2017-12-01

    Grassland degradation is a worldwide problem that often leads to substantial loss of soil organic matter (SOM). Understanding how SOM content influences the stabilization of plant carbon (C) to form soil C is important to evaluate the potential of degraded grasslands to sequester additional C. We conducted a greenhouse experiment using C3 soils with six levels of SOM content and planted the C4 grass Cleistogenes squarrosa and/or added its litter to investigate how SOM content regulates the storage of new soil C derived from litter and roots, the decomposition of extant soil C, and the formation of soil aggregates. We found that microbial biomass carbon (MBC) increased with SOM content, and increased the mineralization of litter C. Both litter addition and planted treatments increased the amount of new C inputs to soil. However, litter addition had no significant impacts on the mineralization of extant soil C, but the presence of living roots significantly accelerated it. Thus, by the end of the experiment, soil C content was significantly higher in the litter addition treatments, but was not affected by planted treatments. The soil macroaggregate fraction increased with SOM content and was positively related to MBC. Overall, our study suggests that as SOM content increases, plant growth and soil microbes become more active, which allows microbes to process more plant-derived C and increases new soil C formation. The interactions between SOM content and plant C inputs should be considered when evaluating soil C turnover in degraded grasslands.

  4. Few apparent short-term effects of elevated soil temperature and increased frequency of summer precipitation on the abundance and taxonomic diversity of desert soil micro- and meso-fauna

    Science.gov (United States)

    Darby, B.J.; Neher, D.A.; Housman, D.C.; Belnap, J.

    2011-01-01

    Frequent hydration and drying of soils in arid systems can accelerate desert carbon and nitrogen mobilization due to respiration, microbial death, and release of intracellular solutes. Because desert microinvertebrates can mediate nutrient cycling, and the autotrophic components of crusts are known to be sensitive to rapid desiccation due to elevated temperatures after wetting events, we studied whether altered soil temperature and frequency of summer precipitation can also affect the composition of food web consumer functional groups. We conducted a two-year field study with experimentally-elevated temperature and frequency of summer precipitation in the Colorado Plateau desert, measuring the change in abundance of nematodes, protozoans, and microarthropods. We hypothesized that microfauna would be more adversely affected by the combination of elevated temperature and frequency of summer precipitation than either effect alone, as found previously for phototrophic crust biota. Microfauna experienced normal seasonal fluctuations in abundance, but the effect of elevated temperature and frequency of summer precipitation was statistically non-significant for most microfaunal groups, except amoebae. The seasonal increase in abundance of amoebae was reduced with combined elevated temperature and increased frequency of summer precipitation compared to either treatment alone, but comparable with control (untreated) plots. Based on our findings, we suggest that desert soil microfauna are relatively more tolerant to increases in ambient temperature and frequency of summer precipitation than the autotrophic components of biological soil crust at the surface.

  5. Influence of long-term fertilization on soil physicochemical properties in a brown soil

    Science.gov (United States)

    Li, Dongdong; Luo, Peiyu; Han, Xiaori; Yang, Jinfeng

    2018-01-01

    This study aims to explore the influence on soil physicochemical properties under a 38-y long-term fertilization in a brown soil. Soil samples (0-20 cm)were taken from the six treatments of the long-term fertilization trial in October 2016:no fertilizer (CK), N1(mineral nitrogen fertilizer), N1P (mineral nitrogen and phosphate fertilizer), N1PK (mineral nitrogen, phosphate and potassic fertilizer), pig manure (M2), M2N1P (pig manure, mineral nitrogen and phosphate fertilizer).The results showed thatthe long-term application of chemical fertilizers reduced soil pH value, while the application of organic fertilizers increased pH value. Fertilization significantly increased the content of AHN, TN and SOM. Compared with the CK treatment and chemical fertilizer treatments, organic fertilizer treatments significantly increased the content of AP and TP. The content of AK and TK were no significant difference in different treatment.

  6. Habitat constraints on the functional significance of soil microbial communities

    Science.gov (United States)

    Nunan, Naoise; Leloup, Julie; Ruamps, Léo; Pouteau, Valérie; Chenu, Claire

    2017-04-01

    An underlying assumption of most ecosystem models is that soil microbial communities are functionally equivalent; in other words, that microbial activity under given set of conditions is not dependent on the composition or diversity of the communities. Although a number of studies have suggested that this assumption is incorrect, ecosystem models can adequately describe ecosystem processes, such as soil C dynamics, without an explicit description of microbial functioning. Here, we provide a mechanistic basis for reconciling this apparent discrepancy. In a reciprocal transplant experiment, we show that microbial communities are not always functionally equivalent. The data suggest that when the supply of substrate is restricted, then the functioning of different microbial communities cannot be distinguished, but when the supply is less restricted, the intrinsic functional differences among communities can be expressed. When the supply of C is restricted then C dynamics are related to the properties of the physical and chemical environment of the soil. We conclude that soil C dynamics may depend on microbial community structure or diversity in environments such as the rhizosphere or the litter layer, but are less likely to do so in oligotrophic environments such as the mineral layers of soil.

  7. Using Agricultural Residue Biochar to Improve Soil Quality of Desert Soils

    Directory of Open Access Journals (Sweden)

    Yunhe Zhang

    2016-03-01

    Full Text Available A laboratory study was conducted to test the effects of biochars made from different feedstocks on soil quality indicators of arid soils. Biochars were produced from four locally-available agricultural residues: pecan shells, pecan orchard prunings, cotton gin trash, and yard waste, using a lab-scale pyrolyzer operated at 450 °C under a nitrogen environment and slow pyrolysis conditions. Two local arid soils used for crop production, a sandy loam and a clay loam, were amended with these biochars at a rate of 45 Mg·ha−1 and incubated for three weeks in a growth chamber. The soils were analyzed for multiple soil quality indicators including soil organic matter content, pH, electrical conductivity (EC, and available nutrients. Results showed that amendment with cotton gin trash biochar has the greatest impact on both soils, significantly increasing SOM and plant nutrient (P, K, Ca, Mn contents, as well as increasing the electrical conductivity, which creates concerns about soil salinity. Other biochar treatments significantly elevated soil salinity in clay loam soil, except for pecan shell biochar amended soil, which was not statistically different in EC from the control treatment. Generally, the effects of the biochar amendments were minimal for many soil measurements and varied with soil texture. Effects of biochars on soil salinity and pH/nutrient availability will be important considerations for research on biochar application to arid soils.

  8. Do shallow soil, low water availability, or their combination increase the competition between grasses with different root systems in karst soil?

    Science.gov (United States)

    Zhao, Yajie; Li, Zhou; Zhang, Jing; Song, Haiyan; Liang, Qianhui; Tao, Jianping; Cornelissen, Johannes H C; Liu, Jinchun

    2017-04-01

    Uneven soil depth and low water availability are the key limiting factors to vegetation restoration and reconstruction in limestone soils such as in vulnerable karst regions. Belowground competition will possibly increase under limited soil resources. Here, we investigate whether low resource availability (including shallow soil, low water availability, and shallow soil and low water availability combined) stimulates the competition between grasses with different root systems in karst soil, by assessing their growth response, biomass allocation, and morphological plasticity. In a full three-way factorial blocked design of soil depth by water availability by neighbor identity, we grew Festuca arundinacea (deep-rooted) and Lolium perenne (shallow-rooted) under normal versus shallow soil depth, high versus low water availability, and in monoculture (conspecific neighbor) versus mixture (neighbor of the other species). The key results were as follows: (1) total biomass and aboveground biomass in either of the species decreased with reduction of resources but were not affected by planting patterns (monoculture or mixture) even at low resource levels. (2) For F. arundinacea, root biomass, root mass fraction, total root length, and root volume were higher in mixture than in monoculture at high resource level (consistent with resource use complementarity), but lower in mixture than in monoculture at low resource levels (consistent with interspecific competition). In contrast for L. perenne, either at high or low resource level, these root traits had mostly similar values at both planting patterns. These results suggest that deep-rooted and shallow-rooted plant species can coexist in karst regions under current climatic regimes. Declining resources, due to shallow soil, a decrease in precipitation, or combined shallow soil and karst drought, increased the root competition between plants of deep-rooted and shallow-rooted species. The root systems of deep-rooted plants may be

  9. Changes in Soil Fungal Community Structure with Increasing Disturbance Frequency.

    Science.gov (United States)

    Cho, Hyunjun; Kim, Mincheol; Tripathi, Binu; Adams, Jonathan

    2017-07-01

    Although disturbance is thought to be important in many ecological processes, responses of fungal communities to soil disturbance have been little studied experimentally. We subjected a soil microcosm to physical disturbance, at a range of frequencies designed to simulate ecological disturbance events. We analyzed the fungal community structure using Illumina HiSeq sequencing of the ITS1 region. Fungal diversity was found to decline with the increasing disturbance frequencies, with no sign of the "humpback" pattern found in many studies of larger sedentary organisms. There is thus no evidence of an effect of release from competition resulting from moderate disturbance-which suggests that competition and niche overlap may not be important in limiting soil fungal diversity. Changing disturbance frequency also led to consistent differences in community composition. There were clear differences in OTU-level composition, with different disturbance treatments each having distinct fungal communities. The functional profile of fungal groups (guilds) was changed by the level of disturbance frequency. These predictable differences in community composition suggest that soil fungi can possess different niches in relation to disturbance frequency, or time since last disturbance. Fungi appear to be most abundant relative to bacteria at intermediate disturbance frequencies, on the time scale we studied here.

  10. [Influences of biochar and nitrogen fertilizer on soil nematode assemblage of upland red soil].

    Science.gov (United States)

    Lu, Yan-yan; Wang, Ming-wei; Chen, Xiao-vun; Liu, Man-qiang; Chen, Xiao-min; Cheng, Yan-hong; Huang, Qian-ru; Hu, Feng

    2016-01-01

    The use of biochar as soil remediation amendment has received more and more concerns, but little attention has been paid to its effect on soil fauna. Based on the field experiment in an upland red soil, we studied the influences of different application rates of biochar (0, 10, 20, 30, 40 t · hm⁻²) and nitrogen fertilizer (60, 90, 120 kg N · hm⁻²) on soil basic properties and nematode assemblages during drought and wet periods. Our results showed that the biochar amendment significantly affect soil moisture and pH regardless of drought or wet period. With the increasing of biochar application, soil pH significantly increased, while soil moisture increased first and then decreased. Soil microbial properties (microbial biomass C, microbial biomass N, microbial biomass C/N, basal respiration) were also significantly affected by the application of biochar and N fertilizer. Low doses of biochar could stimulate the microbial activity, while high doses depressed microbial activity. For example, averaged across different N application rates, biochar amendment at less than 30 t · hm⁻² could increase microbial activity in the drought and wet periods. Besides, the effects of biochar also depended on wet or drought period. When the biochar application rate higher than 30 t · hm⁻², the microbial biomass C was significantly higher in the drought period than the control, but no differences were observed in the wet period. On the contrary, microbial biomass N showed a reverse pattern. Dissolved organic matter and mineral N were affected by biochar and N fertilizer significantly in the drought period, however, in the wet period they were only affected by N fertilizer rather than biochar. There was significant interaction between biochar and N fertilizer on soil nematode abundance and nematode trophic composition independent of sampling period. Combined high doses of both biochar and N fertilization promoted soil nematode abundance. Moreover, the biochar amendment

  11. Root carbon inputs to the rhizosphere stimulate extracellular enzyme activity and increase nitrogen availability in temperate forest soils

    Science.gov (United States)

    Brzostek, E. R.; Phillips, R.; Dragoni, D.; Drake, J. E.; Finzi, A. C.

    2011-12-01

    The mobilization of nitrogen (N) from soil organic matter in temperate forest soils is controlled by the microbial production and activity of extracellular enzymes. The exudation of carbon (C) by tree roots into the rhizosphere may subsidize the microbial production of extracellular enzymes in the rhizosphere and increase the access of roots to N. The objective of this research was to investigate whether rates of root exudation and the resulting stimulation of extracellular enzyme activity in the rhizosphere (i.e., rhizosphere effect) differs between tree species that form associations with ectomycorrhizal (ECM) or arbuscular mycorrhizal (AM) fungi. This research was conducted at two temperate forest sites, the Harvard Forest (HF) in Central MA and the Morgan Monroe State Forest (MMSF) in Southern IN. At the HF, we measured rates of root exudation and the rhizosphere effects on enzyme activity, N cycling, and C mineralization in AM and ECM soils. At the MMSF, we recently girdled AM and ECM dominated plots to examine the impact of severing belowground C allocation on rhizosphere processes. At both sites, the rhizosphere effect on proteolytic, chitinolytic and ligninolytic enzyme activities was greater in ECM soils than in AM soils. In particular, higher rates of proteolytic enzyme activity increased the availability of amino acid-N in ECM rhizospheres relative to the bulk soils. Further, this stimulation of enzyme activity was directly correlated with higher rates of C mineralization in the rhizosphere than in the bulk soil. Although not significantly different between species, root exudation of C comprised 3-10% of annual gross primary production at the HF. At the MMSF, experimental girdling led to a larger decline in soil respiration and enzyme activity in ECM plots than in AM plots. In both ECM and AM soils, however, girdling resulted in equivalent rates of enzyme activity in rhizosphere and corresponding bulk soils. The results of this study contribute to the

  12. Influence of indian mustard (Brassica juncea) on rhizosphere soil solution chemistry in long-term contaminated soils: a rhizobox study.

    Science.gov (United States)

    Kim, Kwon-Rae; Owens, Gary; Kwon, Soon-lk

    2010-01-01

    This study investigated the influence of Indian mustard (Brassica juncea) root exudation on soil solution properties (pH, dissolved organic carbon (DOC), metal solubility) in the rhizosphere using a rhizobox. Measurement was conducted following the cultivation of Indian mustard in the rhizobox filled four different types of heavy metal contaminated soils (two alkaline soils and two acidic soils). The growth of Indian mustard resulted in a significant increase (by 0.6 pH units) in rhizosphere soil solution pH of acidic soils and only a slight increase (soil solution varied considerably amongst different soils, resulting in significant changes to soil solution metals in the rhizosphere. For example, the soil solution Cd, Cu, Pb, and Zn concentrations increased in the rhizosphere of alkaline soils compared to bulk soil following plant cultivation. In contrast, the soluble concentrations of Cd, Pb, and Zn in acidic soils decreased in rhizosphere soil when compared to bulk soils. Besides the influence of pH and DOC on metal solubility, the increase of heavy metal concentration having high stability constant such as Cu and Pb resulted in a release of Cd and Zn from solid phase to liquid phase.

  13. Pedodiversity and Its Significance in the Context of Modern Soil Geography

    Science.gov (United States)

    Krasilnikov, P. V.; Gerasimova, M. I.; Golovanov, D. L.; Konyushkova, M. V.; Sidorova, V. A.; Sorokin, A. S.

    2018-01-01

    Methodological basics of the study and quantitative assessment of pedodiversity are discussed. It is shown that the application of various indices and models of pedodiversity can be feasible for solving three major issues in pedology: a comparative geographical analysis of different territories, a comparative historical analysis of soil development in the course of landscape evolution, and the analysis of relationships between biodiversity and pedodiversity. Analogous geographic concepts of geodiversity and landscape diversity are also discussed. Certain limitations in the use of quantitative estimates of pedodiversity related to their linkage to the particular soil classification systems and with the initial soil maps are considered. Problems of the interpretation of the results of pedodiversity assessments are emphasized. It is shown that scientific explanations of biodiversity cannot be adequately applied in soil studies. Promising directions of further studies of pedodiversity are outlined. They include the assessment of the functional diversity of soils on the basis of data on their properties, integration with geostatistical methods of evaluation of soil variability, and assessment of pedodiversity on different scales.

  14. [Temperature sensitivity of wheat plant respiration and soil respiration influenced by increased UV-B radiation from elongation to flowering periods].

    Science.gov (United States)

    Chen, Shu-Tao; Hu, Zheng-Hua; Li, Han-Mao; Ji, Yu-Hong; Yang, Yan-Ping

    2009-05-15

    Field experiment was carried out in the spring of 2008 in order to investigate the effects of increased UV-B radiation on the temperature sensitivity of wheat plant respiration and soil respiration from elongation to flowering periods. Static chamber-gas chromatography method was used to measure ecosystem respiration and soil respiration under 20% UV-B radiation increase and control. Environmental factors such as temperature and moisture were also measured. Results indicated that supplemental UV-B radiation inhibited the ecosystem respiration and soil respiration from wheat elongation to flowering periods, and the inhibition effect was more obvious for soil respiration than for ecosystem respiration. Ecosystem respiration rates, on daily average, were 9%, 9%, 3%, 16% and 30% higher for control than for UV-B treatment forthe five measurement days, while soil respiration rates were 99%, 93%, 106%, 38% and 10% higher for control than for UV-B treatment. The Q10s (temperature sensitivity coefficients) for plant respiration under control and UV-B treatments were 1.79 and 1.59, respectively, while the Q10s for soil respiration were 1.38 and 1.76, respectively. The Q10s for ecosystem respiration were 1.65 and 1.63 under CK and UV-B treatments, respectively. Supplemental UV-B radiation caused a lower Q10 for plant respiration and a higher Q10 for soil respiration, although no significant effect of supplemental UV-B radiation on the Q10 for ecosystem respiration was found.

  15. Radon soil increases before volcano-tectonic earthquakes in Colombia

    International Nuclear Information System (INIS)

    Garzon, G.; Serna, D.; Diago, J.; Moran, C.

    2003-01-01

    Continuous studies of radon concentration changes in soils for the purpose of earthquake monitoring have been carried out in three colombian districts and in the edifices of Galeras and nevado del Ruiz volcanoes since 1995. In zones of active faulting have been measured radon soil emissions between 1000 and 2500 pCi/L. In an intersection of two active geological faults have been measured levels of 25 000 pCi/L. In the present work appears a compilation of examples of the registered anomalous radon emissions in several stations before earthquakes of tectonic character. Examples of registered radon increases before: (1) events of magnitudes between 2 and 4; (2) the occurrence of seismic swarms; and (3) the Quindio (Colombia) earthquake (M w = 6, 2) of January 1999, are described. A model of transport mechanism for the studied isotopes is presented. (orig.)

  16. Effects of the increased radium content in soil on the soil fauna

    International Nuclear Information System (INIS)

    Krivolutskij, D.A.; Druk, A.Ya.; Semenova, L.M.; Semyashkina, T.M.; Mikhal'tsova, Z.A.

    1978-01-01

    The effect of elevated radioactive background due to the presence of natural radionuclide of radium-226 on soil animals has been studied. The areas being studied (1-2 hectares) had the elevated radioactivity ranging from 50 to 4000 μR/hour and were located on an over-flood-lands terrace with meadow vegetation in the mid-taiga subzone. Histological examination of tegmental epithelium and middle intestine (tissues in direct contact with radium-contaminated soil) was performed on Dendrobaena octaedra (Sav.) and Dendrodrillus rubidus (Sav.) collected from areas with 4000μR/hour radioactivity. A comparison of the results with data obtained earlier for surface animals inhabiting the same areas has corroborated that settled animals inhabiting contaminated areas for a long time suffer from retardation of development and disturbances in the functioning of body epithelium and of the intestine. The effect of radiation on soil animals can be observed in areas with far lower radioactivity (100-200μR/hour), probably due to their closer contact with radium-contaminated soil. The most convenient object for monitoring of the effects of elevated background radioactivity is the earthworm, which is irradiated not only from outside but also from the smallowed soil

  17. Influence of physical and chemical properties of different soil types on optimal soil moisture for tillage

    Directory of Open Access Journals (Sweden)

    Vladimir Zebec

    2017-01-01

    Full Text Available Soil plasticity is the area of soil consistency, i.e. it represents a change in soil condition due to different soil moisture influenced by external forces activity. Consistency determines soil resistance in tillage, therefore, the aim of the research was to determine the optimum soil moisture condition for tillage and the influence of the chemical and physical properties of the arable land horizons on the soil plasticity on three different types of soil (fluvisol, luvisol and humic glaysol. Statistically significant differences were found between all examined soil types, such as the content of clay particles, the density of packaging and the actual and substitution acidity, the cation exchange capacity and the content of calcium. There were also statistically significant differences between the examined types of soil for the plasticity limit, liquid limit and the plasticity index. The average established value of plasticity limit as an important element for determining the optimal moment of soil tillage was 18.9% mass on fluvisol, 24.0% mass on luvisol and 28.6% mass on humic glaysol. Very significant positive direction correlation with plasticity limits was shown by organic matter, clay, fine silt, magnesium, sodium and calcium, while very significant negative direction correlation was shown by hydrolytic acidity, coarse sand, fine sand and coarse silt. Created regression models can estimate the optimal soil moisture condition for soil cultivation based on the basic soil properties. The model precision is significantly increased by introducing a greater number of agrochemical and agrophysical soil properties, and the additional precision of the model can be increased by soil type data.

  18. 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

  19. Impact of drought and increasing temperatures on soil CO2 emissions in a Mediterranean shrubland (gariga)

    DEFF Research Database (Denmark)

    de Dato, Giovanbattista Domenico; De Angelis, Paolo; Sirca, Costantino

    2010-01-01

    the soil and air night-time temperatures and to reduce water input from precipitation. The objective was to analyze the extent to which higher temperatures and a drier climate influence soil CO2 emissions in the short term and on an annual basis. The microclimate was manipulated in field plots (about 25 m2...... temperature probe. The seasonal pattern of soil CO2 efflux was characterized by higher rates during the wet vegetative season and lower rates during the dry non-vegetative season (summer). The Warming treatment did not change SR fluxes at any sampling date. The Drought treatment decreased soil CO2 emissions...... on only three of 10 occasions during 2004. The variation of soil respiration with temperature and soil water content did not differ significantly among the treatments, but was affected by the season. The annual CO2 emissions were not significantly affected by the treatments. In the semi-arid Mediterranean...

  20. Increased nitrogen leaching following soil freezing is due to decreased root uptake in a northern hardwood forest

    Science.gov (United States)

    John L. Campbell; Anne M. Socci; Pamela H. Templer

    2014-01-01

    The depth and duration of snow pack is declining in the northeastern United States as a result of warming air temperatures. Since snow insulates soil, a decreased snow pack can increase the frequency of soil freezing, which has been shown to have important biogeochemical implications. One of the most notable effects of soil freezing is increased inorganic nitrogen...

  1. 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.

  2. Regenerating degraded soils and increasing water use efficiency on vegetable farms in Uruguay through ecological intensification

    NARCIS (Netherlands)

    Alliaume, F.

    2016-01-01

    This thesis investigated alternative soil management strategies for vegetable crop systems and their hypothesized effects on increasing systems resilience by sequestering soil carbon, increasing the efficiency of water use, and reducing erosion. The goal was to contribute knowledge on and tools

  3. CHANGE OF CHOSEN SOIL PHYSICAL PROPERTIES OF CHERNOZEM AFTER SEVEN YEARS OF NO-TILL SOIL CULTIVATION

    Directory of Open Access Journals (Sweden)

    Katarna Hrckov

    2014-09-01

    Full Text Available Soil physical properties were investigated in two types of growing systems - integrated no-till system and conventional system with ploughing, in 1999 2005 on chernozem in maize growing region. Bulk density decreased and total porosity increased during 7 years in both growing systems. In integrated system the improvement of soil physical properties could be explained by remaining of plant residues on soil surface. In conventional system the plant residues were incorporated into soil by ploughing. This led to the higher proportion of organic matter in soil. Soil cultivated conventionally had significantly higher value of reduced bulk density, significantly lower porosity and significantly higher values of soil moisture compared to soil in integrated no-till system. Maximum capillary water capacity was not significantly influenced by soil cultivation. Values of investigated soil physical properties in both systems were not markedly different from the typical values of cultivated chernozem.

  4. Nitrogen Addition and Understory Removal but Not Soil Warming Increased Radial Growth of Pinus cembra at Treeline in the Central Austrian Alps

    Directory of Open Access Journals (Sweden)

    Andreas Gruber

    2018-05-01

    Full Text Available Beside low temperatures, limited tree growth at the alpine treeline may also be attributed to a lack of available soil nutrients and competition with understory vegetation. Although intra-annual stem growth of Pinus cembra has been studied intensively at the alpine treeline, the responses of radial growth to soil warming, soil fertilization, and below ground competition awaits clarification. In this study we quantified the effects of nitrogen (N fertilization, soil warming, and understory removal on stem radial growth of P. cembra at treeline. Soil warming was achieved by roofing the forest floor with a transparent polyvinyl skin, while understory competition was prevented by shading the forest floor with a non-transparent foil around six trees each. Six trees received N- fertilization and six other trees served as controls. Stem growth was monitored with band dendrometers during the growing seasons 2012–2014. Our 3 years experiment showed that soil warming had no considerable effect on radial growth. Though understory removal through shading was accompanied by root-zone cooling, understory removal as well as N fertilization led to a significant increase in radial growth. Hardly affected was tree root biomass, while N-fertilization and understory removal significantly increased in 100-needle surface area and 100-needle dry mass, implying a higher amount of N stored in needles. Overall, our results demonstrate that beside low temperatures, tree growth at cold-climate boundaries may also be limited by root competition for nutrients between trees and understory vegetation. We conclude that tree understory interactions may also control treeline dynamics in a future changing environment.

  5. Using organic matter to increase soil fertility in Burundi: potentials and limitations

    Science.gov (United States)

    Kaboneka, Salvator

    2015-04-01

    Agriculture production in Burundi is dominated by small scale farmers (0.5 ha/household) who have only very limited access to mineral inputs. In the past, farmers have relied on fallow practices combined with farm yard manures to maintain and improve soil fertility. However, due to the high population growth and high population density (370/km²), fallow practices are nowadays no longer feasible, animal manures cannot be produced in sufficient quantities to maintain soil productivity and food insecurity has become a quasi permanent reality. Most Burundian soils are characterized by 1:1 types of clay minerals (kaolinite) and are acidic in nature. Such soils are of very low cation exchange capacity (CEC). To compare the effect of % clays and % organic matter (% C), correlations tests have been conducted between the two parameters and the CEC. It was found that in high altitude kaolinitic and acidic soils, CEC was highly correlated to % C and less correlated to % clay, suggesting that organic matter could play an important role in improving fertility and productivity of these soils. Based on these findings, additional studies have been conducted to evaluate the fertilizer and soil amendment values of animal manures (cattle, goat, chicken), and leguminous (Calliandra calothyrsus, Gliricidia sepium, Senna simea, Senna spectabilis) and non-leguminous (Tithonia diversifolia) foliar biomass. It was observed that chicken manure significantly reduces Al3+ levels in acidic soils, while Tithonia diversifolia outperforms in nutrient releases compared to the commonly known leguminous agroforestry shrubs and trees indicated above. Although the above mentioned organic sources can contribute to the soil nutrients supply, the quantities potentially available on farm are generally small. The only solution is to supplement these organic sources with other organic sources (compost, organic household waste), chemical fertilizers and mineral amendments (lime) to achieve Integrated Soil

  6. Increasing Efficiency of Soil Fertility Map for Rice Cultivation Using Fuzzy Logic, AHP and GIS

    Directory of Open Access Journals (Sweden)

    javad seyedmohammadi

    2017-02-01

    Full Text Available Introduction: With regard to increasing population of country, need to high agricultural production is essential. The most suitable method for this issue is high production per area unit. Preparation much food and other environmental resources with conservation of biotic resources for futures will be possible only with optimum exploitation of soil. Among effective factors for the most production balanced addition of fertilizers increases production of crops higher than the others. With attention to this topic, determination of soil fertility degree is essential tobetter use of fertilizers and right exploitation of soils. Using fuzzy logic and Analytic Hierarchy Process (AHP could be useful in accurate determination of soil fertility degree. Materials and Methods: The study area (at the east of Rasht city is located between 49° 31' to 49° 45' E longitude and 37° 7' to 37° 27' N latitude in north of Guilan Province, northern Iran, in the southern coast of the Caspian sea. 117 soil samples were derived from0-30 cm depth in the study area. Air-dried soil samples were crushed and passed through a 2mm sieve. Available phosphorus, potassium and organic carbon were determined by sodium bicarbonate, normal ammonium acetate and corrected walkly-black method, respectively. In the first stage, the interpolation of data was done by kriging method in GIS context. Then S-shape membership function was defined for each parameter and prepared fuzzy map. After determination of membership function weight parameters maps were determined using AHP technique and finally soil fertility map was prepared with overlaying of weighted fuzzy maps. Relative variance and correlation coefficient criteria used tocontrol groups separation accuracy in fuzzy fertility map. Results and Discussion: With regard to minimum amounts of parameters looks some lands of study area had fertility difficulty. Therefore, soil fertility map of study area distinct these lands and present soil

  7. Straw gasification biochar increases plant available water capacity and plant growth in coarse sandy soil

    DEFF Research Database (Denmark)

    Hansen, Veronika; Hauggaard-Nielsen, Henrik; Petersen, Carsten Tilbæk

    Gasification biochar (GB) contains recalcitrant carbon that can contribute to soil carbon sequestration and soil quality improvement. However, the impact of GB on plant available water capacity (AWC) and plant growth in diverse soil types needs further reserach. A pot experiment with spring barley...... the characteristic low compressibility and high friction giving much better conditions for root penetration increasing yield potentials. Furthermore, risk of drought in dry periods, and nutrient losses in wet periods in coarser soil types is also reduced...

  8. Short-Term Responses of Soil Respiration and C-Cycle Enzyme Activities to Additions of Biochar and Urea in a Calcareous Soil.

    Directory of Open Access Journals (Sweden)

    Dali Song

    Full Text Available Biochar (BC addition to soil is a proposed strategy to enhance soil fertility and crop productivity. However, there is limited knowledge regarding responses of soil respiration and C-cycle enzyme activities to BC and nitrogen (N additions in a calcareous soil. A 56-day incubation experiment was conducted to investigate the combined effects of BC addition rates (0, 0.5, 1.0, 2.5 and 5.0% by mass and urea (U application on soil nutrients, soil respiration and C-cycle enzyme activities in a calcareous soil in the North China Plain. Our results showed soil pH values in both U-only and U plus BC treatments significantly decreased within the first 14 days and then stabilized, and CO2emission rate in all U plus BC soils decreased exponentially, while there was no significant difference in the contents of soil total organic carbon (TOC, dissolved organic carbon (DOC, total nitrogen (TN, and C/N ratio in each treatment over time. At each incubation time, soil pH, electrical conductivity (EC, TOC, TN, C/N ratio, DOC and cumulative CO2 emission significantly increased with increasing BC addition rate, while soil potential activities of the four hydrolytic enzymes increased first and then decreased with increasing BC addition rate, with the largest values in the U + 1.0%BC treatment. However, phenol oxidase activity in all U plus BC soils showed a decreasing trend with the increase of BC addition rate. Our results suggest that U plus BC application at a rate of 1% promotes increases in hydrolytic enzymes, does not highly increase C/N and C mineralization, and can improve in soil fertility.

  9. Short-Term Responses of Soil Respiration and C-Cycle Enzyme Activities to Additions of Biochar and Urea in a Calcareous Soil

    Science.gov (United States)

    Song, Dali; Xi, Xiangyin; Huang, Shaomin; Liang, Guoqing; Sun, Jingwen; Zhou, Wei; Wang, Xiubin

    2016-01-01

    Biochar (BC) addition to soil is a proposed strategy to enhance soil fertility and crop productivity. However, there is limited knowledge regarding responses of soil respiration and C-cycle enzyme activities to BC and nitrogen (N) additions in a calcareous soil. A 56-day incubation experiment was conducted to investigate the combined effects of BC addition rates (0, 0.5, 1.0, 2.5 and 5.0% by mass) and urea (U) application on soil nutrients, soil respiration and C-cycle enzyme activities in a calcareous soil in the North China Plain. Our results showed soil pH values in both U-only and U plus BC treatments significantly decreased within the first 14 days and then stabilized, and CO2emission rate in all U plus BC soils decreased exponentially, while there was no significant difference in the contents of soil total organic carbon (TOC), dissolved organic carbon (DOC), total nitrogen (TN), and C/N ratio in each treatment over time. At each incubation time, soil pH, electrical conductivity (EC), TOC, TN, C/N ratio, DOC and cumulative CO2 emission significantly increased with increasing BC addition rate, while soil potential activities of the four hydrolytic enzymes increased first and then decreased with increasing BC addition rate, with the largest values in the U + 1.0%BC treatment. However, phenol oxidase activity in all U plus BC soils showed a decreasing trend with the increase of BC addition rate. Our results suggest that U plus BC application at a rate of 1% promotes increases in hydrolytic enzymes, does not highly increase C/N and C mineralization, and can improve in soil fertility. PMID:27589265

  10. Effects of Two Kinds of Biochars on Soil Cu Availability in Contaminated Soil

    Directory of Open Access Journals (Sweden)

    WANG Xiao-qi

    2016-07-01

    Full Text Available This paper is aimed to research the impacts of different biochars(0,1%,2%,4%, including maize biochar and phytolacca root biochar, on rape growth and the soil Cu availability in the Cu-contaminated red soil via a series of pot experiments. The results showed that, compared with the control, the addition of two kinds of biochars could increase the biomass of the rape. In low Cu-contaminated red soil, added 4% maize biochar and phytolacca root biochar increased the biomass by 21.2 times and 67.9 times; however, the biomass were increased by 8.6 times and 109.6 times under high Cu-contaminated soil. The addition of phytolacca root biochar could increase the soil pH significantly, which has been increased by 0.4~1.6 units with the addition of phytolacca root biochar in low Cu-contaminated red soil, and it had 0.25~1.35 units more than that with maize biochar; In high Cu-contaminated red soil, with the addition of phytolacca root biochar, soil pH was increased by 0.33~1.52 units, which was 0.3~1.25 units higher than maize biochar. There was a significant effect on reducing the soil Cu availability with the addition of the two biochars. Among them, 4% addition of maize biochar and phytolacca root biochar could reduce soil available Cu content by 21.9% and 45.2% in low Cu-contaminated soil, however, it was decreased by 41.9% and 53.8% in high Cu-contaminated soil. Both of the two biochars were able to reduce the Cu accumulation in rape, where there was a decrease by 21.2% and 67.8% with he addition of 4% maize biochar and phytolacca root biochar under low Cu-contaminated soil, and it was decreased by 19.9% and 66.8% in high Cu-contaminated soil respectively. Both of the biochars could ameliorate the acidity and Cu availability in the red soil, enhance the biomass of the rape and reduce the Cu accumulation in rape, but phytolacca root biochar had more effective influence than maize biochar.

  11. Interaction Among Machine Traffic, Soil Physical Properties and Loblolly Pine Root Prolifereation in a Piedmont Soil

    Science.gov (United States)

    Emily A. Carter; Timothy P. McDonald

    1997-01-01

    The impact of forwarder traffic on soil physical properties was evaluated on a Gwinnett sandy loam, a commonly found soil of the Piedmont. Soil strength and saturated hydraulic conductivity were significantly altered by forwarder traffic, but reductions in air-filled porosity also occurred. Bulk density did not increase significantly in trafficked treatments. The...

  12. Dynamics of bacterial communities in two unpolluted soils after spiking with phenanthrene: soil type specific and common responders

    Directory of Open Access Journals (Sweden)

    Guo-Chun eDing

    2012-08-01

    Full Text Available Considering their key role for ecosystem processes, it is important to understand the response of microbial communities in unpolluted soils to pollution with polycyclic aromatic hydrocarbons (PAH. Phenanthrene, a model compound for PAH, was spiked to a Cambisol and a Luvisol soil. Total community DNA from phenanthrene-spiked and control soils collected on days 0, 21 and 63 were analyzed based on PCR-amplified 16S rRNA genefragments. Denaturing gradient gel electrophoresis (DGGE fingerprints of bacterial communities increasingly deviated with time between spiked and control soils. In taxon specific DGGE, significant responses of Alphaproteobacteria and Actinobacteria became only detectable after 63 days, while significant effects on Betaproteobacteria were detectable in both soils after 21 days. Comparison of the taxonomic distribution of bacteria in spiked and control soils on day 63 as revealed by pyrosequencing indicated soil type specific negative effects of phenanthrene on several taxa, many of them belonging to the Gamma-, Beta- or Deltaproteobacteria. Bacterial richness and evenness decreased in spiked soils. Despite the significant differences in the bacterial community structure between both soils on day 0, similar genera increased in relative abundance after PAH spiking, especially Sphingomonas and Polaromonas. However, this did not result in an increased overall similarity of the bacterial communities in both soils.

  13. Increases in soil water content after the mortality of non-native trees in oceanic island forest ecosystems are due to reduced water loss during dry periods.

    Science.gov (United States)

    Hata, Kenji; Kawakami, Kazuto; Kachi, Naoki

    2016-03-01

    The control of dominant, non-native trees can alter the water balance of soils in forest ecosystems via hydrological processes, which results in changes in soil water environments. To test this idea, we evaluated the effects of the mortality of an invasive tree, Casuarina equisetifolia Forst., on the water content of surface soils on the Ogasawara Islands, subtropical islands in the northwestern Pacific Ocean, using a manipulative herbicide experiment. Temporal changes in volumetric water content of surface soils at 6 cm depth at sites where all trees of C. equisetifolia were killed by herbicide were compared with those of adjacent control sites before and after their mortality with consideration of the amount of precipitation. In addition, the rate of decrease in the soil water content during dry periods and the rate of increase in the soil water content during rainfall periods were compared between herbicide and control sites. Soil water content at sites treated with herbicide was significantly higher after treatment than soil water content at control sites during the same period. Differences between initial and minimum values of soil water content at the herbicide sites during the drying events were significantly lower than the corresponding differences in the control quadrats. During rainfall periods, both initial and maximum values of soil water contents in the herbicided quadrats were higher, and differences between the maximum and initial values did not differ between the herbicided and control quadrats. Our results indicated that the mortality of non-native trees from forest ecosystems increased water content of surface soils, due primarily to a slower rate of decrease in soil water content during dry periods. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Effects of aluminium water treatment residuals, used as a soil amendment to control phosphorus mobility in agricultural soils.

    Science.gov (United States)

    Ulén, Barbro; Etana, Ararso; Lindström, Bodil

    2012-01-01

    Phosphorus (P) leaching from agricultural soils is a serious environmental concern. Application of aluminium water treatment residuals (Al-WTRs) at a rate of 20 Mg ha(-1) to clay soils from central Sweden significantly increased mean topsoil P sorption index (PSI) from 4.6 to 5.5 μmol kg(-1) soil. Mean degree of P saturation in ammonium lactate extract (DPS-AL) significantly decreased from 17 to 13%, as did plant-available P (P-AL). Concentrations of dissolved reactive P (DRP) decreased by 10-85% in leaching water with Al-WTR treatments after exposure of topsoil lysimeters to simulated rain. Soil aggregate stability (AgS) for 15 test soils rarely improved. Three soils (clay loam, silty loam and loam sand) were tested in greenhouse pot experiments. Aluminium-WTR application of 15 or 30 ton ha(-1) to loam sand and a clay loam with P-AL values of 80-100 mg kg(-1) soil significantly increased growth of Italian ryegrass when fertilised with P but did not significantly affect growth of spring barley on any soil. Al-WTR should only be applied to soils with high P fertility where improved crop production is not required.

  15. 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

  16. Increases in soil aggregation following phosphorus additions in a tropical premontane forest are not driven by root and arbuscular mycorrhizal fungal abundances

    Science.gov (United States)

    Camenzind, Tessa; Papathanasiou, Helena; Foerster, Antje; Dietrich, Karla; Hertel, Dietrich; Homeier, Juergen; Oelmann, Yvonne; Olsson, Pål Axel; Suárez, Juan; Rillig, Matthias

    2015-12-01

    Tropical ecosystems have an important role in global change scenarios, in part because they serve as a large terrestrial carbon pool. Carbon protection is mediated by soil aggregation processes, whereby biotic and abiotic factors influence the formation and stability of aggregates. Nutrient additions may affect soil structure indirectly by simultaneous shifts in biotic factors, mainly roots and fungal hyphae, but also via impacts on abiotic soil properties. Here, we tested the hypothesis that soil aggregation will be affected by nutrient additions primarily via changes in arbuscular mycorrhizal fungal (AMF) hyphae and root length in a pristine tropical forest system. Therefore, the percentage of water-stable macroaggregates (> 250µm) (WSA) and the soil mean weight diameter (MWD) was analyzed, as well as nutrient contents, pH, root length and AMF abundance. Phosphorus additions significantly increased the amount of WSA, which was consistent across two different sampling times. Despite a positive effect of phosphorus additions on extraradical AMF biomass, no relationship between WSA and extra-radical AMF nor roots was revealed by regression analyses, contrary to the proposed hypothesis. These findings emphasize the importance of analyzing soil structure in understudied tropical systems, since it might be affected by increasing nutrient deposition expected in the future.

  17. Increases in soil aggregation following phosphorus additions in a tropical premontane forest are not driven by root and arbuscular mycorrhizal fungal abundances

    Directory of Open Access Journals (Sweden)

    Tessa eCamenzind

    2016-01-01

    Full Text Available Tropical ecosystems have an important role in global change scenarios, in part because they serve as a large terrestrial carbon pool. Carbon protection is mediated by soil aggregation processes, whereby biotic and abiotic factors influence the formation and stability of aggregates. Nutrient additions may affect soil structure indirectly by simultaneous shifts in biotic factors, mainly roots and fungal hyphae, but also via impacts on abiotic soil properties. Here, we tested the hypothesis that soil aggregation will be affected by nutrient additions primarily via changes in arbuscular mycorrhizal fungal (AMF hyphae and root length in a pristine tropical forest system. Therefore, the percentage of water-stable macroaggregates (> 250µm (WSA and the soil mean weight diameter (MWD was analyzed, as well as nutrient contents, pH, root length and AMF abundance. Phosphorus additions significantly increased the amount of WSA, which was consistent across two different sampling times. Despite a positive effect of phosphorus additions on extraradical AMF biomass, no relationship between WSA and extra-radical AMF nor roots was revealed by regression analyses, contrary to the proposed hypothesis. These findings emphasize the importance of analyzing soil structure in understudied tropical systems, since it might be affected by increasing nutrient deposition expected in the future.

  18. Stability of titania nanoparticles in soil suspensions and transport in saturated homogeneous soil columns

    International Nuclear Information System (INIS)

    Fang Jing; Shan Xiaoquan; Wen Bei; Lin Jinming; Owens, Gary

    2009-01-01

    The stability of TiO 2 nanoparticles in soil suspensions and their transport behavior through saturated homogeneous soil columns were studied. The results showed that TiO 2 could remain suspended in soil suspensions even after settling for 10 days. The suspended TiO 2 contents in soil suspensions after 24 h were positively correlated with the dissolved organic carbon and clay content of the soils, but were negatively correlated with ionic strength, pH and zeta potential. In soils containing soil particles of relatively large diameters and lower solution ionic strengths, a significant portion of the TiO 2 (18.8-83.0%) readily passed through the soils columns, while TiO 2 was significantly retained by soils with higher clay contents and salinity. TiO 2 aggregate sizes in the column outflow significantly increased after passing through the soil columns. The estimated transport distances of TiO 2 in some soils ranged from 41.3 to 370 cm, indicating potential environmental risk of TiO 2 nanoparticles to deep soil layers. - TiO 2 nanoparticles could efficiently suspend in soil suspensions and potentially transport to deeper soil layers

  19. Stability of titania nanoparticles in soil suspensions and transport in saturated homogeneous soil columns

    Energy Technology Data Exchange (ETDEWEB)

    Fang Jing [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Shan Xiaoquan [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China)], E-mail: xiaoquan@rcees.ac.cn; Wen Bei [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China)], E-mail: bwen@rcees.ac.cn; Lin Jinming [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Owens, Gary [Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095 (Australia)

    2009-04-15

    The stability of TiO{sub 2} nanoparticles in soil suspensions and their transport behavior through saturated homogeneous soil columns were studied. The results showed that TiO{sub 2} could remain suspended in soil suspensions even after settling for 10 days. The suspended TiO{sub 2} contents in soil suspensions after 24 h were positively correlated with the dissolved organic carbon and clay content of the soils, but were negatively correlated with ionic strength, pH and zeta potential. In soils containing soil particles of relatively large diameters and lower solution ionic strengths, a significant portion of the TiO{sub 2} (18.8-83.0%) readily passed through the soils columns, while TiO{sub 2} was significantly retained by soils with higher clay contents and salinity. TiO{sub 2} aggregate sizes in the column outflow significantly increased after passing through the soil columns. The estimated transport distances of TiO{sub 2} in some soils ranged from 41.3 to 370 cm, indicating potential environmental risk of TiO{sub 2} nanoparticles to deep soil layers. - TiO{sub 2} nanoparticles could efficiently suspend in soil suspensions and potentially transport to deeper soil layers.

  20. Hydrologic effects of large southwestern USA wildfires significantly increase regional water supply: fact or fiction?

    Science.gov (United States)

    Wine, M. L.; Cadol, D.

    2016-08-01

    In recent years climate change and historic fire suppression have increased the frequency of large wildfires in the southwestern USA, motivating study of the hydrological consequences of these wildfires at point and watershed scales, typically over short periods of time. These studies have revealed that reduced soil infiltration capacity and reduced transpiration due to tree canopy combustion increase streamflow at the watershed scale. However, the degree to which these local increases in runoff propagate to larger scales—relevant to urban and agricultural water supply—remains largely unknown, particularly in semi-arid mountainous watersheds co-dominated by winter snowmelt and the North American monsoon. To address this question, we selected three New Mexico watersheds—the Jemez (1223 km2), Mogollon (191 km2), and Gila (4807 km2)—that together have been affected by over 100 wildfires since 1982. We then applied climate-driven linear models to test for effects of fire on streamflow metrics after controlling for climatic variability. Here we show that, after controlling for climatic and snowpack variability, significantly more streamflow discharged from the Gila watershed for three to five years following wildfires, consistent with increased regional water yield due to enhanced infiltration-excess overland flow and groundwater recharge at the large watershed scale. In contrast, we observed no such increase in discharge from the Jemez watershed following wildfires. Fire regimes represent a key difference between the contrasting responses of the Jemez and Gila watersheds with the latter experiencing more frequent wildfires, many caused by lightning strikes. While hydrologic dynamics at the scale of large watersheds were previously thought to be climatically dominated, these results suggest that if one fifth or more of a large watershed has been burned in the previous three to five years, significant increases in water yield can be expected.

  1. Maize, switchgrass, and ponderosa pine biochar added to soil increased herbicide sorption and decreased herbicide efficacy.

    Science.gov (United States)

    Clay, Sharon A; Krack, Kaitlynn K; Bruggeman, Stephanie A; Papiernik, Sharon; Schumacher, Thomas E

    2016-08-02

    Biochar, a by-product of pyrolysis made from a wide array of plant biomass when producing biofuels, is a proposed soil amendment to improve soil health. This study measured herbicide sorption and efficacy when soils were treated with low (1% w/w) or high (10% w/w) amounts of biochar manufactured from different feedstocks [maize (Zea mays) stover, switchgrass (Panicum vigatum), and ponderosa pine (Pinus ponderosa)], and treated with different post-processing techniques. Twenty-four hour batch equilibration measured sorption of (14)C-labelled atrazine or 2,4-D to two soil types with and without biochar amendments. Herbicide efficacy was measured with and without biochar using speed of seed germination tests of sensitive species. Biochar amended soils sorbed more herbicide than untreated soils, with major differences due to biochar application rate but minor differences due to biochar type or post-process handling technique. Biochar presence increased the speed of seed germination compared with herbicide alone addition. These data indicate that biochar addition to soil can increase herbicide sorption and reduce efficacy. Evaluation for site-specific biochar applications may be warranted to obtain maximal benefits without compromising other agronomic practices.

  2. Evaluation of the increasing in the LRd soil natural radioactivity as result of phosphogypsum application

    International Nuclear Information System (INIS)

    Parreira, Paulo S.; Appoloni, Carlos R.; Paula, Fernando R. de

    1997-01-01

    The aim of this paper is to analyze the detection sensitiveness for the radionuclides from 238 U and 232 Th series present in a LRd soil from the Londrina City region, to verify the amount of radioactivity increase in that soil due to the use of phosphogypsum, and as a preliminary phase for a detailed investigation on the behaviour of those elements in agricultural soils. (author). 11 refs., 3 tab

  3. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    Science.gov (United States)

    Yang, X. M.; Drury, C. F.; Reynolds, W. D.; Yang, J. Y.

    2016-06-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2-53 μm) and sand (53-2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg-1 soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg-1, but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation.

  4. Relationships between soil erosion risk, soil use and soil properties in Mediterranean areas. A comparative study of three typical sceneries

    Science.gov (United States)

    Gil, Juan; Priego-Navas, Mercedes; Zavala, Lorena M.; Jordán, Antonio

    2013-04-01

    Generally, literature shows that the high variability of rainfall-induced soil erosion is related to climatic differences, relief, soil properties and land use. Very different runoff rates and soil loss values have been reported in Mediterranean cropped soils depending on soil management practices, but also in soils under natural vegetation types. OBJECTIVES The aim of this research is to study the relationships between soil erosion risk, soil use and soil properties in three typical Mediterranean areas from southern Spain: olive groves under conventional tillage, minimum tillage and no-till practices, and soils under natural vegetation. METHODS Rainfall simulation experiments have been carried out in order to assess the relationship between soil erosion risk, land use, soil management and soil properties in olive-cropped soils under different types of management and soils under natural vegetation type from Mediterranean areas in southern Spain RESULTS Results show that mean runoff rates decrease from 35% in olive grove soils under conventional tillage to 25% in olive (Olea europaea) grove soils with minimum tillage or no-till practices, and slightly over 22% in soils under natural vegetation. Moreover, considering the different vegetation types, runoff rates vary in a wide range, although runoff rates from soils under holm oak (Quercus rotundifolia), 25.70%, and marginal olive groves , 25.31%, are not significantly different. Results from soils under natural vegetation show that the properties and nature of the organic residues play a role in runoff characteristics, as runoff rates above 50% were observed in less than 10% of the rainfall simulations performed on soils with a organic layer. In contrast, more than half of runoff rates from bare soils reached or surpassed 50%. Quantitatively, average values for runoff water losses increase up to 2.5 times in unprotected soils. This is a key issue in the study area, where mean annual rainfall is above 600 mm

  5. [Effects of controlled release blend bulk urea on soil nitrogen and soil enzyme activity in wheat and rice fields].

    Science.gov (United States)

    Zhang, Jing Sheng; Wang, Chang Quan; Li, Bing; Liang, Jing Yue; He, Jie; Xiang, Hao; Yin, Bin; Luo, Jing

    2017-06-18

    A field experiment was conducted to investigate the effect of controlled-release fertilizer (CRF) combined with urea (UR) on the soil fertility and environment in wheat-rice rotation system. Changes in four forms of nitrogen (total nitrogen, ammonium nitrogen, nitrate nitrogen, and microbial biomass nitrogen) and in activities of three soil enzymes participating in nitrogen transformation (urease, protease, and nitrate reductase) were measured in seven fertilization treatments (no fertilization, routine fertilization, 10%CRF+90%UR, 20%CRF+80%UR, 40%CRF+60%UR, 80%CRF+20%UR, and 100%CRF). The results showed that soil total nitrogen was stable in the whole growth period of wheat and rice. There was no significant difference among the treatments of over 20% CRF in soil total nitrogen content of wheat and rice. The soil inorganic nitrogen content was increased dramatically in treatments of 40% or above CRF during the mid-late growing stages of wheat and rice. With the advance of the growth period, conventional fertilization significantly decreased soil microbial biomass nitrogen, but the treatments of 40% and above CRF increased the soil microbial biomass nitrogen significantly. The soil enzyme activities were increased with over 40% of CRF in the mid-late growing stage of wheat and rice. By increasing the CRF ratio, the soil protease activity and nitrate reductase activity were improved gradually, and peaked in 100% CRF. The treatments of above 20% CRF could decrease the urease activity in tillering stage of rice and delay the peak of ammonium nitrogen, which would benefit nitrogen loss reduction. The treatments of 40% and above CRF were beneficial to improving soil nitrogen supply and enhancing soil urease and protease activities, which could promote the effectiveness of nitrogen during the later growth stages of wheat and rice. The 100% CRF treatment improved the nitrate reductase activity significantly during the later stage of wheat and rice. Compared with the

  6. Exposure to dairy manure leads to greater antibiotic resistance and increased mass-specific respiration in soil microbial communities

    Science.gov (United States)

    Avera, Bethany; Badgley, Brian; Barrett, John E.; Franklin, Josh; Knowlton, Katharine F.; Ray, Partha P.; Smitherman, Crystal

    2017-01-01

    Intensifying livestock production to meet the demands of a growing global population coincides with increases in both the administration of veterinary antibiotics and manure inputs to soils. These trends have the potential to increase antibiotic resistance in soil microbial communities. The effect of maintaining increased antibiotic resistance on soil microbial communities and the ecosystem processes they regulate is unknown. We compare soil microbial communities from paired reference and dairy manure-exposed sites across the USA. Given that manure exposure has been shown to elicit increased antibiotic resistance in soil microbial communities, we expect that manure-exposed sites will exhibit (i) compositionally different soil microbial communities, with shifts toward taxa known to exhibit resistance; (ii) greater abundance of antibiotic resistance genes; and (iii) corresponding maintenance of antibiotic resistance would lead to decreased microbial efficiency. We found that bacterial and fungal communities differed between reference and manure-exposed sites. Additionally, the β-lactam resistance gene ampC was 5.2-fold greater under manure exposure, potentially due to the use of cephalosporin antibiotics in dairy herds. Finally, ampC abundance was positively correlated with indicators of microbial stress, and microbial mass-specific respiration, which increased 2.1-fold under manure exposure. These findings demonstrate that the maintenance of antibiotic resistance associated with manure inputs alters soil microbial communities and ecosystem function. PMID:28356447

  7. Exposure to dairy manure leads to greater antibiotic resistance and increased mass-specific respiration in soil microbial communities.

    Science.gov (United States)

    Wepking, Carl; Avera, Bethany; Badgley, Brian; Barrett, John E; Franklin, Josh; Knowlton, Katharine F; Ray, Partha P; Smitherman, Crystal; Strickland, Michael S

    2017-03-29

    Intensifying livestock production to meet the demands of a growing global population coincides with increases in both the administration of veterinary antibiotics and manure inputs to soils. These trends have the potential to increase antibiotic resistance in soil microbial communities. The effect of maintaining increased antibiotic resistance on soil microbial communities and the ecosystem processes they regulate is unknown. We compare soil microbial communities from paired reference and dairy manure-exposed sites across the USA. Given that manure exposure has been shown to elicit increased antibiotic resistance in soil microbial communities, we expect that manure-exposed sites will exhibit (i) compositionally different soil microbial communities, with shifts toward taxa known to exhibit resistance; (ii) greater abundance of antibiotic resistance genes; and (iii) corresponding maintenance of antibiotic resistance would lead to decreased microbial efficiency. We found that bacterial and fungal communities differed between reference and manure-exposed sites. Additionally, the β-lactam resistance gene ampC was 5.2-fold greater under manure exposure, potentially due to the use of cephalosporin antibiotics in dairy herds. Finally, ampC abundance was positively correlated with indicators of microbial stress, and microbial mass-specific respiration, which increased 2.1-fold under manure exposure. These findings demonstrate that the maintenance of antibiotic resistance associated with manure inputs alters soil microbial communities and ecosystem function. © 2017 The Author(s).

  8. Climate-change effects on soils: Accelerated weathering, soil carbon and elemental cycling

    Energy Technology Data Exchange (ETDEWEB)

    Qafoku, Nikolla

    2015-04-01

    Climate change [i.e., high atmospheric carbon dioxide (CO2) concentrations (≥400 ppm); increasing air temperatures (2-4°C or greater); significant and/or abrupt changes in daily, seasonal, and inter-annual temperature; changes in the wet/dry cycles; intensive rainfall and/or heavy storms; extended periods of drought; extreme frost; heat waves and increased fire frequency] is and will significantly affect soil properties and fertility, water resources, food quantity and quality, and environmental quality. Biotic processes that consume atmospheric CO2, and create organic carbon (C) that is either reprocessed to CO2 or stored in soils are the subject of active current investigations, with great concern over the influence of climate change. In addition, abiotic C cycling and its influence on the inorganic C pool in soils is a fundamental global process in which acidic atmospheric CO2 participates in the weathering of carbonate and silicate minerals, ultimately delivering bicarbonate and Ca2+ or other cations that precipitate in the form of carbonates in soils or are transported to the rivers, lakes, and oceans. Soil responses to climate change will be complex, and there are many uncertainties and unresolved issues. The objective of the review is to initiate and further stimulate a discussion about some important and challenging aspects of climate-change effects on soils, such as accelerated weathering of soil minerals and resulting C and elemental fluxes in and out of soils, soil/geo-engineering methods used to increase C sequestration in soils, soil organic matter (SOM) protection, transformation and mineralization, and SOM temperature sensitivity. This review reports recent discoveries, identifies key research needs, and highlights opportunities offered by the climate-change effects on soils.

  9. Avoidance bio-assays may help to test the ecological significance of soil pollution

    International Nuclear Information System (INIS)

    Martinez Aldaya, Maite; Lors, Christine; Salmon, Sandrine; Ponge, Jean-Francois

    2006-01-01

    We measured the short-term (100 min) avoidance of a soil heavily polluted by hydrocarbons by the soil springtail Folsomia candida, at six rates of dilution in a control, unpolluted soil. We compared the results with those of long-term (40-day) population tests. Five strains were compared, of varying geographical and ecological origin. When pure, the polluted soil was lethal in the long-term and avoided in the short-term by all strains. Avoidance tests, but not population tests, were able to discriminate between strains. Avoidance thresholds differed among strains. Two ecological consequences of the results were discussed: (i) toxic compounds may kill soil animals or deprive them from food, resulting in death of populations, (ii) pollution spots can be locally deprived of fauna because of escape movements of soil animals. Advantages and limitations of the method have been listed, together with proposals for their wider use in soil ecology and ecotoxicology. - Polluted soils are avoided by soil animals, a phenomenon which can be used as a cheap, sensitive tool for the early detection of environmental risk

  10. Pretreatment of Cr(VI)-amended soil with chromate-reducing rhizobacteria decreases plant toxicity and increases the yield of Pisum sativum.

    Science.gov (United States)

    Soni, Sumit K; Singh, Rakshapal; Singh, Mangal; Awasthi, Ashutosh; Wasnik, Kundan; Kalra, Alok

    2014-05-01

    Pot culture experiments were performed under controlled greenhouse conditions to investigate whether four Cr(VI)-reducing bacterial strains (SUCR44, SUCR140, SUCR186, and SUCR188) were able to decrease Cr toxicity to Pisum sativum plants in artificially Cr(VI)-contaminated soil. The effect of pretreatment of soil with chromate-reducing bacteria on plant growth, chromate uptake, bioaccumulation, nodulation, and population of Rhizobium was found to be directly influenced by the time interval between bacterial treatment and seed sowing. Pretreatment of soil with SUCR140 (Microbacterium sp.) 15 days before sowing (T+15) showed a maximum increase in growth and biomass in terms of root length (93 %), plant height (94 %), dry root biomass (99 %), and dry shoot biomass (99 %). Coinoculation of Rhizobium with SUCR140 further improved the aforementioned parameter. Compared with the control, coinoculation of SUCR140+R showed a 117, 116, 136, and 128 % increase, respectively, in root length, plant height, dry root biomass, and dry shoot biomass. The bioavailability of Cr(VI) decreased significantly in soil (61 %) and in uptake (36 %) in SUCR140-treated plants; the effects of Rhizobium, however, either alone or in the presence of SUCR140, were not significant. The populations of Rhizobium (126 %) in soil and nodulation (146 %) in P. sativum improved in the presence of SUCR140 resulting in greater nitrogen (54 %) concentration in the plants. This study shows the usefulness of efficient Cr(VI)-reducing bacterial strain SUCR140 in improving yields probably through decreased Cr toxicity and improved symbiotic relationship of the plants with Rhizobium. Further decrease in the translocation of Cr(VI) through improved nodulation by Rhizobium in the presence of efficient Cr-reducing bacterial strains could also decrease the accumulation of Cr in shoots.

  11. Increased soil stable nitrogen isotopic ratio following phosphorus enrichment: historical patterns and tests of two hypotheses in a phosphorus-limited wetland

    DEFF Research Database (Denmark)

    Inglett, P.W.; Reddy, K.R.; Newmann, S.

    2007-01-01

    on the δ15N of NH4+ and significantly increased the δ15N of water-extractable organic N. Measurements of surface soils collected during a field mesocosm experiment also revealed no significant effect of P on δ15N even after 5 years of P addition. In contrast, δ15N of leaf and root tissues of hydroponically...

  12. [Soil hydrolase characteristics in late soil-thawing period in subalpine/alpine forests of west Sichuan].

    Science.gov (United States)

    Tan, Bo; Wu, Fu-Zhong; Yang, Wan-Qin; Yu, Sheng; Yang, Yu-Lian; Wang, Ao

    2011-05-01

    Late soil-thawing period is a critical stage connecting winter and growth season. The significant temperature fluctuation at this stage might have strong effects on soil ecological processes. In order to understand the soil biochemical processes at this stage in the subalpine/alpine forests of west Sichuan, soil samples were collected from the representative forests including primary fir forest, fir and birch mixed forest, and secondary fir forest in March 5-April 25, 2009, with the activities of soil invertase, urease, and phosphatase (neutral, acid and alkaline phosphatases) measured. In soil frozen period, the activities of the three enzymes in test forests still kept relatively higher. With the increase of soil temperature, the activities of hydrolases at the early stage of soil-thawing decreased rapidly after a sharp increase, except for neutral phosphatease. Thereafter, there was an increase in the activities of urease and phosphatase. Relative to soil mineral layer, soil organic layer had higher hydrolase activity in late soil-thawing period, and showed more obvious responses to the variation of soil temperature.

  13. Grape yield, and must compounds of 'Cabernet Sauvignon' grapevine in sandy soil with potassium contents increasing

    Directory of Open Access Journals (Sweden)

    Marlise Nara Ciotta

    2016-08-01

    Full Text Available ABSTRACT: Content of exchangeable potassium (K in t soil may influence on its content in grapevines leaves, grape yield, as well as, in must composition. The study aimed to assess the interference of exchangeable K content in the soil on its leaf content, production and must composition of 'Cabernet Sauvignon' cultivar. In September 2011, in Santana do Livramento (RS five vineyards with increasing levels of exchangeable K in the soil were selected. In the 2012/13 and 2013/14 harvests, the grape yield, yield components, total K content in the leaves in full bloom and berries veraison were evaluated. Values of total soluble sugar (TSS, pH, total titratable acidity (TTA, total polyphenols and anthocyanins were evaluated in the must. Exchangeable K content increase in soil with sandy surface texture increased its content in leaves collected during full flowering and in berries and must pH; however, it did not affect production of the 'Cabernet Sauvignon'.

  14. Soil enzyme dynamics in chlorpyrifos-treated soils under the influence of earthworms.

    Science.gov (United States)

    Sanchez-Hernandez, Juan C; Notario Del Pino, J; Capowiez, Yvan; Mazzia, Christophe; Rault, Magali

    2018-01-15

    Earthworms contribute, directly and indirectly, to contaminant biodegradation. However, most of bioremediation studies using these annelids focus on pollutant dissipation, thus disregarding the health status of the organism implied in bioremediation as well as the recovery of indicators of soil quality. A microcosm study was performed using Lumbricus terrestris to determine whether earthworm density (2 or 4individuals/kg wet soil) and the time of exposure (1, 2, 6, 12, and 18wk) could affect chlorpyrifos persistence in soil initially treated with 20mg active ingredientkg -1 wet soil. Additionally, selected earthworm biomarkers and soil enzyme activities were measured as indicators of earthworm health and soil quality, respectively. After an 18-wk incubation period, no earthworm was killed by the pesticide, but clear signs of severe intoxication were detected, i.e., 90% inhibition in muscle acetylcholinesterase and carboxylesterase (CbE) activities. Unexpectedly, the earthworm density had no significant impact on chlorpyrifos dissipation rate, for which the measured half-life ranged between 30.3d (control soils) and 44.5d (low earthworm density) or 36.7d (high earthworm density). The dynamic response of several soil enzymes to chlorpyrifos exposure was examined calculating the geometric mean and the treated-soil quality index, which are common enzyme-based indexes of microbial functional diversity. Both indexes showed a significant and linear increase of the global enzyme response after 6wk of chlorpyrifos treatment in the presence of earthworms. Examination of individual enzymes revealed that soil CbE activity could decrease chlorpyrifos-oxon impact upon the rest of enzyme activities. Although L. terrestris was found not to accelerate chlorpyrifos dissipation, a significant increase in the activity of soil enzyme activities was achieved compared with earthworm-free, chlorpyrifos-treated soils. Therefore, the inoculation of organophosphorus-contaminated soils with L

  15. Impacts of Steel-Slag-Based Silicate Fertilizer on Soil Acidity and Silicon Availability and Metals-Immobilization in a Paddy Soil.

    Directory of Open Access Journals (Sweden)

    Dongfeng Ning

    Full Text Available Slag-based silicate fertilizer has been widely used to improve soil silicon- availability and crop productivity. A consecutive early rice-late rice rotation experiment was conducted to test the impacts of steel slag on soil pH, silicon availability, rice growth and metals-immobilization in paddy soil. Our results show that application of slag at a rate above higher or equal to 1 600 mg plant-available SiO2 per kg soil increased soil pH, dry weight of rice straw and grain, plant-available Si concentration and Si concentration in rice shoots compared with the control treatment. No significant accumulation of total cadmium (Cd and lead (Pb was noted in soil; rather, the exchangeable fraction of Cd significantly decreased. The cadmium concentrations in rice grains decreased significantly compared with the control treatment. In conclusion, application of steel slag reduced soil acidity, increased plant-availability of silicon, promoted rice growth and inhibited Cd transport to rice grain in the soil-plant system.

  16. Factors mediating the restoration of structurally degraded soils

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Moldrup, Per; Schjønning, Per

    with the ability of soils to perform these functions. The present study examines the roles of clay mineralogy, native organic matter, and exogenous organic material on the restoration of structurally degraded soils. Totally seven soils from Denmark and Ghana - five soils dominated by illites, one kaolinitic soil...... the incubation period, structural stability estimated as the amount of water-dispersible clay decreased with prevailing moisture content, and native organic matter. Also, microbial activity significantly increased with addition of exogenous organic matter. At the end of incubation, there was significant...... macroaggregation, decreased bulk density, and increased equivalent pore diameter and tortuosity (derived from measurements of soil-gas diffusivity and soil-air permeability) for all soils. Although aggregate friability was not affected by clay type, aggregate workability was highest for the kaolinitic soil...

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

    OpenAIRE

    Ima Yudha Perwira; Kiwako S. Araki; Motoki Kubo; Dinesh Adhikari

    2016-01-01

    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 p...

  18. [Effects of intensive management on soil C and N pools and soil enzyme activities in Moso bamboo plantations.

    Science.gov (United States)

    Yang, Meng; Li, Yong Fu; Li, Yong Chun; Xiao, Yong Heng; Yue, Tian; Jiang, Pei Kun; Zhou, Guo Mo; Liu, Juan

    2016-11-18

    In order to elucidate the effects of intensive management on soil carbon pool, nitrogen pool, enzyme activities in Moso bamboo (Phyllostachys pubescens) plantations, we collected soil samples from the soil surface (0-20 cm) and subsurface (20-40 cm) layers in the adjacent Moso bamboo plantations with extensive and intensive managements in Sankou Township, Lin'an City, Zhejiang Province. We determined different forms of C, N and soil invertase, urease, catalase and acid phosphatase activities. The results showed that long-term intensive management of Moso bamboo plantations significantly decreased the content and storage of soil organic carbon (SOC), with the SOC storage in the soil surface and subsurface layers decreased by 13.2% and 18.0%, respectively. After 15 years' intensive management of Masoo bamboo plantations, the contents of soil water soluble carbon (WSOC), hot water soluble carbon (HWSOC), microbial carbon (MBC) and readily oxidizable carbon (ROC) were significantly decreased in the soil surface and subsurface layers. The soil N storage in the soil surface and subsurface layers in intensively managed Moso bamboo plantations increased by 50.8% and 36.6%, respectively. Intensive management significantly increased the contents of nitrate-N (NO 3 - -N) and ammonium-N (NH 4 + -N), but decreased the contents of water-soluble nitrogen (WSON) and microbial biomass nitrogen (MBN). After 15 years' intensive management of Masoo bamboo plantations, the soil invertase, urease, catalase and acid phosphatase activities in the soil surface layer were significantly decreased, the soil acid phosphatase activity in the soil subsurface layer were significantly decreased, and other enzyme activities in the soil subsurface layer did not change. In conclusion, long-term intensive management led to a significant decline of soil organic carbon storage, soil labile carbon and microbial activity in Moso bamboo plantations. Therefore, we should consider the use of organic

  19. Soil invertebrate fauna affect N2 O emissions from soil.

    Science.gov (United States)

    Kuiper, Imke; de Deyn, Gerlinde B; Thakur, Madhav P; van Groenigen, Jan Willem

    2013-09-01

    Nitrous oxide (N2 O) emissions from soils contribute significantly to global warming. Mitigation of N2 O emissions is severely hampered by a lack of understanding of its main controls. Fluxes can only partly be predicted from soil abiotic factors and microbial analyses - a possible role for soil fauna has until now largely been overlooked. We studied the effect of six groups of soil invertebrate fauna and tested the hypothesis that all of them increase N2 O emissions, although to different extents. We conducted three microcosm experiments with sandy soil and hay residue. Faunal groups included in our experiments were as follows: fungal-feeding nematodes, mites, springtails, potworms, earthworms and isopods. In experiment I, involving all six faunal groups, N2 O emissions declined with earthworms and potworms from 78.4 (control) to 37.0 (earthworms) or 53.5 (potworms) mg N2 O-N m(-2) . In experiment II, with a higher soil-to-hay ratio and mites, springtails and potworms as faunal treatments, N2 O emissions increased with potworms from 51.9 (control) to 123.5 mg N2 O-N m(-2) . Experiment III studied the effect of potworm density; we found that higher densities of potworms accelerated the peak of the N2 O emissions by 5 days (P soil aeration by the soil fauna reduced N2 O emissions in experiment I, whereas in experiment II N2 O emissions were driven by increased nitrogen and carbon availability. In experiment III, higher densities of potworms accelerated nitrogen and carbon availability and N2 O emissions, but did not increase them. Overall, our data show that soil fauna can suppress, increase, delay or accelerate N2 O emissions from soil and should therefore be an integral part of future N2 O studies. © 2013 John Wiley & Sons Ltd.

  20. Biochar has no effect on soil respiration across Chinese agricultural soils.

    Science.gov (United States)

    Liu, Xiaoyu; Zheng, Jufeng; Zhang, Dengxiao; Cheng, Kun; Zhou, Huimin; Zhang, Afeng; Li, Lianqing; Joseph, Stephen; Smith, Pete; Crowley, David; Kuzyakov, Yakov; Pan, Genxing

    2016-06-01

    Biochar addition to soil has been widely accepted as an option to enhance soil carbon sequestration by introducing recalcitrant organic matter. However, it remains unclear whether biochar will negate the net carbon accumulation by increasing carbon loss through CO2 efflux from soil (soil respiration). The objectives of this study were to address: 1) whether biochar addition increases soil respiration; and whether biochar application rate and biochar type (feedstock and pyrolyzing system) affect soil respiration. Two series of field experiments were carried out at 8 sites representing the main crop production areas in China. In experiment 1, a single type of wheat straw biochar was amended at rates of 0, 20 and 40 tha(-1) in four rice paddies and three dry croplands. In experiment 2, four types of biochar (varying in feedstock and pyrolyzing system) were amended at rates of 0 and 20 tha(-1) in a rice paddy under rice-wheat rotation. Results showed that biochar addition had no effect on CO2 efflux from soils consistently across sites, although it increased topsoil organic carbon stock by 38% on average. Meanwhile, CO2 efflux from soils amended with 40 t of biochar did not significantly higher than soils amended with 20 t of biochar. While the biochars used in Experiment 2 had different carbon pools and physico-chemical properties, they had no effect on soil CO2 efflux. The soil CO2 efflux following biochar addition could be hardly explained by the changes in soil physic-chemical properties and in soil microbial biomass. Thus, we argue that biochar will not negate the net carbon accumulation by increasing carbon loss through CO2 efflux in agricultural soils. Copyright © 2016. Published by Elsevier B.V.

  1. Soil resistance and resilience to mechanical stresses for three differently managed sandy loam soils

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Schjønning, Per; Møldrup, Per

    2012-01-01

    carbon (CCCsoils to compaction using air permeability (ka), void ratio (e) and air-filled porosity (ε) as functional indicators and to characterise aggregate stability, strength and friability. Aggregate tensile strength...... the compression index and a proposed functional index,was significantly greater for theMFC soil compared to the other two soils. The change in compression index with initial void ratio was significantly less for the MFC than the other soils. Plastic reorganisation of the soil particles immediately after......To improve our understanding of how clay-organic carbon dynamics affect soil aggregate strength and physical resilience, we selected three nearby soils (MFC,Mixed Forage Cropping; MCC,Mixed Cash Cropping; CCC, Cereal Cash Cropping)with identical clay content and increasing contents of organic...

  2. Conversion of traditional cropland into teak plantations strongly increased soil erosion in montane catchments of Southeastern Asia (Northern Laos; 2002-2014)

    Science.gov (United States)

    Evrard, O.; Ribolzi, O.; Huon, S.; de Rouw, A.; Silvera, N.; Latsachack, K. O.; Soulileuth, B.; Lefèvre, I.; Pierret, A.; Lacombe, G.; Sengtaheuanghoung, O.; Valentin, C.

    2017-12-01

    Soil erosion delivers an excessive quantity of sediment to rivers of Southeastern Asia. Land use is rapidly changing in this region of the world, and these modifications may further accelerate soil erosion in this area. Although the conversion of forests into cropland has often been investigated, much fewer studies have addressed the replacement of traditional slash-and-burn cultivation systems with commercial perennial monocultures such as teak plantations. The current research investigated the impact of this land use change on the hydrological response and the sediment yields from a representative catchment of Northern Laos (Houay Pano, 0.6 km²) where long-term monitoring (2002-2014) was conducted (http://msec.obs-mip.fr/). The results showed a significant growth in the overland flow contribution to stream flow (from 16 to 31%). Furthermore, sediment yields strongly increased from 98 to 609 Mg km-2. These changes illustrate the severity of soil erosion processes occurring under teak plantations characterized by the virtual absence of understorey vegetation to dissipate raindrop energy, which facilitates the formation of an impermeable surface crust. This counter-intuitive increase of soil erosion generated by afforestation reflects the difficulty to find sustainable production solutions for the local populations of Southeastern Asia. To reduce soil loss under teak plantations, the development of extensive agro-forestry practices could be promoted.

  3. How can soil organic carbon stocks in agriculture be maintained or increased?

    Science.gov (United States)

    Don, Axel; Leifeld, Jens

    2015-04-01

    CO2 emissions from soils are 10 times higher than anthropogenic CO2 emissions from fossil burning with around 60 Pg C a-1. At the same time around 60 Pg of carbon is added to the soils as litter from roots and leaves. Thus, the balance between both fluxes is supposed to be zero for the global earth system in steady state without human perturbations. However, the global carbon flux has been altered by humans since thousands of years by extracting biomass carbon as food, feed and fiber with global estimate of 40% of net primary productivity (NPP). This fraction is low in forests but agricultural systems, in particular croplands, are systems with a high net exported carbon fraction. Soils are mainly input driven systems. Agricultural soils depend on input to compensate directly for i) respiration losses, ii) extraction of carbon (and nitrogen) and depletion (e.g. via manure) or indirectly via enhances NPP (e.g. via fertilization management). In a literature review we examined the role of biomass extraction and carbon input via roots, crop residues and amendments (manure, slurry etc.) to agricultural soil's carbon stocks. Recalcitrance of biomass carbon was found to be of minor importance for long-term carbon storage. Thus, also the impact of crop type on soil carbon dynamics seems mainly driven by the amount of crop residuals of different crop types. However, we found distinct differences in the efficiency of C input to refill depleted soil C stocks between above ground C input or below ground root litter C input, with root-C being more efficient due to slower turnover rates. We discuss the role of different measures to decrease soil carbon turnover (e.g. decreased tillage intensity) as compared to measures that increase C input (e.g. cover crops) in the light of global developments in agricultural management with ongoing specialization and segregation between catch crop production and dairy farms.

  4. Long-term no-tillage application increases soil organic carbon, nitrous oxide emissions and faba bean (Vicia faba L.) yields under rain-fed Mediterranean conditions.

    Science.gov (United States)

    Badagliacca, Giuseppe; Benítez, Emilio; Amato, Gaetano; Badalucco, Luigi; Giambalvo, Dario; Laudicina, Vito Armando; Ruisi, Paolo

    2018-05-20

    The introduction of legumes into crop sequences and the reduction of tillage intensity are both proposed as agronomic practices to mitigate the soil degradation and negative impact of agriculture on the environment. However, the joint effects of these practices on nitrous oxide (N 2 O) and ammonia (NH 3 ) emissions from soil remain unclear, particularly concerning semiarid Mediterranean areas. In the frame of a long-term field experiment (23 years), a 2-year study was performed on the faba bean (Vicia faba L.) to evaluate the effects of the long-term use of no tillage (NT) compared to conventional tillage (CT) on yield and N 2 O and NH 3 emissions from a Vertisol in a semiarid Mediterranean environment. Changes induced by the tillage system in soil bulk density, water filled pore space (WFPS), organic carbon (TOC) and total nitrogen (TN), denitrifying enzyme activity (DEA), and bacterial gene (16S, amoA, and nosZ) abundance were measured as parameters potentially affecting N gas emissions. No tillage, compared with CT, significantly increased the faba bean grain yield by 23%. The tillage system had no significant effect on soil NH 3 emissions. Total N 2 O emissions, averaged over two cropping seasons, were higher in NT than those in CT plots (2.58 vs 1.71 kg N 2 O-N ha -1 , respectively; P emissions in NT plots were ascribed to the increase of soil bulk density and WFPS, bacteria (16S abundance was 96% higher in NT than that in CT) and N cycle genes (amoA and nosZ abundances were respectively 154% and 84% higher in NT than that in CT). The total N 2 O emissions in faba bean were similar to those measured in other N-fertilized crops. In conclusion, a full evaluation of NT technique, besides the benefits on soil characteristics (e.g. TOC increase) and crop yield, must take into account some criticisms related to the increase of N 2 O emissions compared to CT. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Modelling the impact of increasing soil sealing on runoff coefficients at regional scale: a hydropedological approach

    Directory of Open Access Journals (Sweden)

    Ungaro Fabrizio

    2014-03-01

    Full Text Available Soil sealing is the permanent covering of the land surface by buildings, infrastructures or any impermeable artificial material. Beside the loss of fertile soils with a direct impact on food security, soil sealing modifies the hydrological cycle. This can cause an increased flooding risk, due to urban development in potential risk areas and to the increased volumes of runoff. This work estimates the increase of runoff due to sealing following urbanization and land take in the plain of Emilia Romagna (Italy, using the Green and Ampt infiltration model for two rainfall return periods (20 and 200 years in two different years, 1976 and 2008. To this goal a hydropedological approach was adopted in order to characterize soil hydraulic properties via locally calibrated pedotransfer functions (PTF. PTF inputs were estimated via sequential Gaussian simulations coupled with a simple kriging with varying local means, taking into account soil type and dominant land use. Results show that in the study area an average increment of 8.4% in sealed areas due to urbanization and sprawl induces an average increment in surface runoff equal to 3.5 and 2.7% respectively for 20 and 200-years return periods, with a maximum > 20% for highly sealed coast areas.

  6. [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.

  7. Physical Properties of Sandy Soil Affected by Soil Conditioner Under Wetting and Drying cycles

    Directory of Open Access Journals (Sweden)

    M.I. Choudhary

    1998-06-01

    Full Text Available Information on the effectiveness of soil conditioners over a prolonged period is scarce. A laboratory experiment was undertaken to evaluate the effectiveness of a polyacrylamide (Broadleaf P4 soil conditioner on the physical properties of sandy soil subjected to wetting and drying cycles. Four concentrations of Broadleaf P4 0, 0.2, 0.4, and 0.6% on dry weight basis were uniformly mixed with a calcareous sandy soil. Addition of Broadleaf P4 to sandy soil increased the water holding capacity, decreased the bulk density, and increased the porosity and void ratio at 0 and 16 wetting and drying cycles. The coefficient of linear extensibility increased considerably with increasing concentrations of the polymer. The addition of polymer at 0 and 16 cycles increased considerably the retention and availability of water in sandy soil. Saturated hydraulic conductivity decreased with increasing concentrations of Broadleaf P4 whereas unsaturated hydraulic conductivity at 0 and 16 cycles showed an increase with increasing soil moisture contents. After I6 wetting and drying cycles, the capacity of the soil to hold water was lost on average by 15.8% when compared to the 0 wetting and drying cycle. The effectiveness of the soil conditioner on bulk density, coefficient of linear extensibility, available water and saturated hydraulic conductivity was reduced on average by 14.1, 24.5, 21.l and 53.7% respectively. The significant changes in soil properties between 0 and 16 cycles suggested that the effectiveness of the conditioner decreased with the application of wetting and drying cycles. However, its effect was still considerable when compared to untreated soil under laboratory conditions.

  8. Fire effects on soil and hydrology

    NARCIS (Netherlands)

    Stoof, C.R.

    2011-01-01

    Fire can significantly increase a landscape’s vulnerability to flooding and erosion events. By removing vegetation, changing soil properties and inducing soil water repellency, fire can increase the risk and erosivity of overland flow. Mitigation of land degradation and flooding events after

  9. [Dynamics of aquic brown soil enzyme activities under no-tillage].

    Science.gov (United States)

    Liu, Xiumei; Li, Qi; Liang, Wenju; Jiang, Yong; Wen, Dazhong

    2006-12-01

    This paper studied the effects of no-tillage on the dynamics of invertase, urease and acid phosphatase activities in an aquic brown soil during maize growing season. The results showed that in 0 - 10 cm soil layer, the invertase activity at jointing, trumpet-shaped and ripening stages, urease activity at jointing and booting stages, and acid phosphatase activity at booting and ripening stages were significantly higher under no-tillage (NT) than under conventional tillage (CT). In 10 - 20 cm soil layer, the invertase activity at seedling, jointing and trumpet-shaped stages was significantly different between NT and CT, and the urease activity during whole growing season except at booting stage was significantly higher under NT than under CT. In 20 - 30 cm soil layer, the invertase activity during maize growing season was significantly lower under NT than under CT, and urease activity at seedling stage and acid phosphate activity at ripening stage were significantly different between these two treatments. Under NT, there was a decreasing trend of soil enzyme activities with increasing soil depth; while under CT, soil invertase and acid phosphatase activities increased, but urease activity decreased with increasing soil depth.

  10. Soil compaction: Evaluation of stress transmission and resulting soil structure

    Science.gov (United States)

    Naveed, Muhammad; Schjønning, Per; Keller, Thomas; Lamande, Mathieu

    2016-04-01

    Accurate estimation of stress transmission and resultant deformation in soil profiles is a prerequisite for the development of predictive models and decision support tools for preventing soil compaction. Numerous studies have been carried out on the effects of soil compaction, whilst relatively few studies have focused on the cause (mode of stress transmission in the soil). We have coupled both cause and effects together in the present study by carrying out partially confined compression tests on (1) wet aggregates, (2) air dry aggregates, and (3) intact soils to quantify stress transmission and compaction-resulted soil structure at the same time. Stress transmission was quantified using both X-ray CT and Tactilus sensor mat, and soil-pore structure was quantified using X-ray CT. Our results imply that stress transmission through soil highly depends on the magnitude of applied load and aggregate strength. As soon as the applied load is lower than the aggregate strength, the mode of stress transmission is discrete as stresses were mainly transmitted through chain of aggregates. With increasing applied load soil aggregates start deforming that transformed heterogeneous soil into homogenous, as a result stress transmission mode was shifted from discrete towards more like a continuum. Continuum-like stress transmission mode was better simulated with Boussinesq (1885) model based on theory of elasticity compared to discrete. The soil-pore structure was greatly affected by increasing applied stresses. Total porosity was reduced 5-16% and macroporosity 50-85% at 620 kPa applied stress for the intact soils. Similarly, significant changes in the morphological indices of the macropore space were also observed with increasing applied stresses.

  11. Biochar Application in Malaysian Sandy and Acid Sulfate Soils: Soil Amelioration Effects and Improved Crop Production over Two Cropping Seasons

    Directory of Open Access Journals (Sweden)

    Theeba Manickam

    2015-12-01

    Full Text Available The use of biochar as an agricultural soil improvement was tested in acid sulfate and sandy soils from Malaysia, cropped with rice and corn. Malaysia has an abundance of waste rice husks that could be used to produce biochar. Rice husk biochar was produced in a gasifier at a local mill in Kelantan as well as in the laboratory using a controlled, specially designed, top lift up draft system (Belonio unit. Rice husk biochar was applied once to both soils at two doses (2% and 5%, in a pot set up that was carried out for two cropping seasons. Positive and significant crop yield effects were observed for both soils, biochars and crops. The yield effects varied with biochar type and dosage, with soil type and over the cropping seasons. The yield increases observed for the sandy soil were tentatively attributed to significant increases in plant-available water contents (from 4%–5% to 7%–8%. The yield effects in the acid sulfate soil were likely a consequence of a combination of (i alleviation of plant root stress by aluminum (Ca/Al molar ratios significantly increased, from around 1 to 3–5 and (ii increases in CEC. The agricultural benefits of rice husk biochar application to Malaysian soils holds promise for its future use.

  12. Diversity and Abundance of Soil Animals as Influenced by Long-Term Fertilization in Grey Desert Soil, China

    Directory of Open Access Journals (Sweden)

    Maibo Jiang

    2015-08-01

    Full Text Available The relationship between soil fauna and different fertilizer management practices is of growing concern. The aim of this research was to investigate the response of soil fauna to fertilization regimes, to explore the relationships among the community of soil animals, soil moisture and crop yields. The application of organic fertilizers (i.e., sheep manure or crop residues increased crop yields and promoted the number of individuals and species of soil fauna owing to the exogenous organic matter that fertilizers provided for the survival and development of soil fauna. Furthermore, the treatments that applied sheep manure (i.e., sheep manure only or nitrogen, phosphorus, potassium and sheep manure plus were significantly beneficial for increasing crop yields and diversity of soil fauna compared to treatments with crop residues returned (i.e., crop residues returned only or nitrogen, phosphorus, potassium and crop residues returned to the field (p < 0.05 due to the response of soil fauna to diverse exogenous nutrients and the effect of soil fertility. Therefore, the finding that soil fauna abundance is significantly positively correlated with soil moisture and crop yield may mean the effects of fertilizer applications on soil animals were partly masked by the soil moisture and crop yield.

  13. 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

  14. Fractionation of Uranium Forms as Affected by Spiked Soil Treatment and Soil Type

    International Nuclear Information System (INIS)

    Lotfy, S.M.; Mostafa, A.Z.; Abdel-Sabour, M.F.

    2012-01-01

    In a fractionation experiment Uranium forms were compared in two soil types (Mostorud and Elgabalelasfar soil). Also, the variation of U forms due to soil treatment (spiking) were studied. In case of Mostorud soil the initial U - fractions were 45.63 % as residual form, 20.69 % organically bound 16.36 % Mn and Fe oxides bound, 9.76% Carbonate form, 7.41 % exchangeable fractions and 0.15% water soluble fractions. These fractions varied significantly when the soil was spiked with 200 mg U/Kg soil to 46.88 %, 23.19 %, 9.97 %, 16.07 %, 3.79% and 0.10% for residual, organically, Mn- Fe oxide, carbonate, exchangeable and water soluble fractions respectively. These result showed significant reduction in U-ex fraction forms and Mn- Fe bound forms with significant increase in U- carbonate form due to U application. In case of Elgabalelasfar soil, the main U - fractions were 57.42% as residual form (relatively higher residual - U form in the clayey soil) 16.10 % organically bound, 13.78% Mn and Fe oxides bound, 7.22 % Carbonate form, 5.23 % exchangeable fractions and 0.25 % water soluble fractions The application of 200 mg U/Kg soil resulted in a significant changes in U - Fractions distribution as follows : 59.26 % , 11.27 % , 19.59 % , 6.84 % , 2.90 % and 0.14 % for residual , organic , Mn- Fe oxides , carbonate, exchangeable and water soluble fractions , respectively.

  15. Nutrient amendment does not increase mineralisation of sequestered carbon during incubation of a nitrogen limited mangrove soil

    KAUST Repository

    Keuskamp, Joost A.

    2013-02-01

    Mangrove forests are sites of intense carbon and nutrient cycling, which result in soil carbon sequestration on a global scale. Currently, mangrove forests receive increasing quantities of exogenous nutrients due to coastal development. The present paper quantifies the effects of nutrient loading on microbial growth rates and the mineralisation of soil organic carbon (SOC) in two mangrove soils contrasting in carbon content. An increase in SOC mineralisation rates would lead to the loss of historically sequestered carbon and an enhanced CO2 release from these mangrove soils.In an incubation experiment we enriched soils from Avicennia and Rhizophora mangrove forests bordering the Red Sea with different combinations of nitrogen, phosphorus and glucose to mimic the effects of wastewater influx. We measured microbial growth rates as well as carbon mineralisation rates in the natural situation and after enrichment. The results show that microbial growth is energy limited in both soils, with nitrogen as a secondary limitation. Nitrogen amendment increased the rate at which labile organic carbon was decomposed, while it decreased SOC mineralisation rates. Such an inhibitory effect on SOC mineralisation was not found for phosphorus enrichment.Our data confirm the negative effect of nitrogen enrichment on the mineralisation of recalcitrant carbon compounds found in other systems. Based on our results it is not to be expected that nutrient enrichment by itself will cause degradation of historically sequestered soil organic carbon in nitrogen limited mangrove forests. © 2012 Elsevier Ltd.

  16. Effects of Soil Temperature and Moisture on Soil Respiration on the Tibetan Plateau.

    Science.gov (United States)

    Bao, Xiaoying; Zhu, Xiaoxue; Chang, Xiaofeng; Wang, Shiping; Xu, Burenbayin; Luo, Caiyun; Zhang, Zhenhua; Wang, Qi; Rui, Yichao; Cui, Xiaoying

    2016-01-01

    Understanding of effects of soil temperature and soil moisture on soil respiration (Rs) under future warming is critical to reduce uncertainty in predictions of feedbacks to atmospheric CO2 concentrations from grassland soil carbon. Intact cores with roots taken from a full factorial, 5-year alpine meadow warming and grazing experiment in the field were incubated at three different temperatures (i.e. 5, 15 and 25°C) with two soil moistures (i.e. 30 and 60% water holding capacity (WHC)) in our study. Another experiment of glucose-induced respiration (GIR) with 4 h of incubation was conducted to determine substrate limitation. Our results showed that high temperature increased Rs and low soil moisture limited the response of Rs to temperature only at high incubation temperature (i.e. 25°C). Temperature sensitivity (Q10) did not significantly decrease over the incubation period, suggesting that substrate depletion did not limit Rs. Meanwhile, the carbon availability index (CAI) was higher at 5°C compared with 15 and 25°C incubation, but GIR increased with increasing temperature. Therefore, our findings suggest that warming-induced decrease in Rs in the field over time may result from a decrease in soil moisture rather than from soil substrate depletion, because warming increased root biomass in the alpine meadow.

  17. Response of soil physicochemical properties and enzyme activities to long-term reclamation of coastal saline soil, Eastern China.

    Science.gov (United States)

    Xie, Xuefeng; Pu, Lijie; Wang, Qiqi; Zhu, Ming; Xu, Yan; Zhang, Meng

    2017-12-31

    Soil enzyme activity during different years of reclamation and land use patterns could indicate changes in soil quality. The objective of this research is to explore the dynamics of 5 soil enzyme activities (dehydrogenase, amylase, urease, acid phosphatase and alkaline phosphatase) involved in C, N, and P cycling and their responses to changes in soil physicochemical properties resulting from long-term reclamation of coastal saline soil. Soil samples from a total of 55 sites were collected from a coastal reclamation area with different years of reclamation (0, 7, 32, 40, 63a) in this study. The results showed that both long-term reclamation and land use patterns have significant effects on soil physicochemical properties and enzyme activities. Compared with the bare flat, soil water content, soil bulk density, pH and electrical conductivity showed a decreasing trend after reclamation, whereas soil organic carbon, total nitrogen and total phosphorus tended to increase. Dehydrogenase, amylase and acid phosphatase activities initially increased and then decreased with increasing years of reclamation, whereas urease and alkaline phosphatase activities were characterized by an increase-decrease-increase trend. Moreover, urease, acid phosphatase and alkaline phosphatase activities exhibited significant differences between coastal saline soil with 63years of reclamation and bare flat, whereas dehydrogenase and amylase activities remained unchanged. Aquaculture ponds showed higher soil water content, pH and EC but lower soil organic carbon, total nitrogen and total phosphorus than rapeseed, broad bean and wheat fields. Rapeseed, broad bean and wheat fields displayed higher urease and alkaline phosphatase activities and lower dehydrogenase, amylase and acid phosphatase activities compared with aquaculture ponds. Redundancy analysis revealed that the soil physicochemical properties explained 74.5% of the variation in soil enzyme activities and that an obvious relationship

  18. Drivers of increased organic carbon concentrations in stream water following forest disturbance: Separating effects of changes in flow pathways and soil warming

    Science.gov (United States)

    Schelker, J.; Grabs, T.; Bishop, K.; Laudon, H.

    2013-12-01

    disturbance such as clear-cutting has been identified as an important factor for increasing dissolved organic carbon (DOC) concentrations in boreal streams. We used a long-term data set of soil temperature, soil moisture, shallow groundwater (GW) levels, and stream DOC concentrations from three boreal first-order streams to investigate mechanisms causing these increases. Clear-cutting was found to alter soil conditions with warmer and wetter soils during summer. The application of a riparian flow concentration integration model (RIM) explained a major part of variation in stream [DOC] arising from changing flow pathways in riparian soils during the pretreatment period (r2 = 0.4-0.7), but less well after the harvest. Model residuals were sensitive to changes in soil temperature. The linear regression models for the temperature dependence of [DOC] in soils were not different in the disturbed and undisturbed catchments, whereas a nonlinear response to soil moisture was found. Overall these results suggest that the increased DOC mobilization after forest disturbance is caused by (i) increased GW levels leading to increased water fluxes in shallow flow path in riparian soils and (ii) increased soil temperature increasing the DOC availability in soils during summer. These relationships indicate that the mechanisms of DOC mobilization after forest disturbance are not different to those of undisturbed catchments, but that catchment soils respond to the higher hydro-climatic variation observed after clear-cutting. This highlights the sensitivity of boreal streams to changes in the energy and water balance, which may be altered as a result of both land management and climate change.

  19. Application of Bioameliorant and Biofertilizers to Increase the Soil Health and Rice Productivity

    Directory of Open Access Journals (Sweden)

    Tualar Simarmata

    2016-10-01

    Full Text Available The major rice intensity of diseases in Indonesia was increased significantly and has caused a yield loss of up to 20–30%. The experiments had been conducted to investigate the effect of bioameliorant or composted straw (CS combined with consortia of biofertilizers (CB and biocontrol agent to restore the soil health and promote the induced systemic resistance (ISR for increasing the rice productivity. The experiment arranged as randomized block design consisted of 12 treatments (0, 2.5, 5.0 and 7.5 ton of CS per ha combined with 400 g of CB and 200 g inoculant of CB + 200 g inoculant of Trichoderma sp and was provided with three replications. The experimental results revealed that application of 2.5–7.5 ton per ha of bioameliorant combined with 400 g per ha of CB and 400 g Trichoderma sp has increased the ISR and enhanced the rice productivity significantly. The brown spot, sheath rice blight and bacterial leaf blight diseases were reduced from 16.7% to 3.3–8.0%, 20% to 4–10%, 24% to 2.7–4.7% and 20.7% to 8–14.0%, respectively at 7 weeks after transplanting. In addition, the rice grain yield was increased from about 7.1 ton ha−1 to 7.9–10.1 ton per ha.

  20. [Effects of elevated temperature on soil organic carbon and soil respiration under subalpine coniferous forest in western Sichuan Province, China].

    Science.gov (United States)

    Pan, Xin-li; Lin, Bo; Liu, Qing

    2008-08-01

    To investigate the effects of elevated temperature on the soil organic carbon content, soil respiration rate, and soil enzyme activities in subalpine Picea asperata plantations in western Sichuan Province of China, a simulation study was conducted in situ with open-top chambers from November 2005 to July 2007. The results showed that under elevated temperature, the mean air temperature and soil temperature were 0.42 degrees C and 0.25 degrees C higher than the control, respectively. In the first and the second year, the increased temperature had somewhat decreasing effects on the soil organic carbon and the C/N ratio at the soil depths of 0-10 cm and 10-20 cm. In the first year the soil organic carbon and the C/N ratio in 0-10 cm soil layer decreased by 8.69%, and 8.52%, respectively; but in the second year, the decrements were lesser. Soil respiration rate was significantly enhanced in the first year of warming, but had no significant difference with the control in the second year. In the first year of warming, the activities of soil invertase, polyphenol oxidase, catalase, protease, and urease increased, and the invertase and polyphenol oxidase activities in 0-10 cm soil layer were significantly higher than the control. In the second year of warming, the activities of invertase, protease and urease still had an increase, but those of catalase and polyphenol oxidase had a downtrend, compared with the control.

  1. Soil water repellency of the artificial soil and natural soil in rocky slopes as affected by the drought stress and polyacrylamide.

    Science.gov (United States)

    Chen, Zhang; Wang, Ruixin; Han, Pengyuan; Sun, Hailong; Sun, Haifeng; Li, Chengjun; Yang, Lixia

    2018-04-01

    Soil water repellency (SWR) causes reduced soil water storage, enhanced runoff and reduced ecosystem productivity. Therefore, characterization of SWR is a prerequisite for effective environmental management. SWR has been reported under different soils, land uses and regions of the world, particularly in forest land and after wildfires; however, the understanding of this variable in the artificial soil of rocky slope eco-engineering is still rather limited. This study presented the characterization of SWR in the artificial soil affected by the polyacrylamide (PAM) and drought stress. There were two molecular weights of PAM, and the CK was without PAM application. Three types of soil were studied: natural soil and two types of artificial soil which have been sprayed for 1y and 5y, respectively. The drought stress experiments had three drought gradients, lasted for three weeks. Water repellency index (WRI) and soil-water contact angle (β) were determined using intrinsic sorptivity method by measuring the water sorptivity (S W ) and ethanol sorptivity (S E ) in all soil samples. The results showed that (1) Polyacrylamide treatments significantly increased S W by 3% to 38%, and reduced S E by 1% to 15%, WRI by 6% to 38%, β by 3% to 23% compared to the control group. Polyacrylamide treatments also increased water-stable aggregates content and total porosity by 22% to 33%, 11% to 20% relative to the control, while PAM with a higher molecular weight performed best. (2) The interaction between PAM and drought stress had a significant effect on WRI and β for all soil types (Pnatural soil. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Effect of Soil pH Increase by Biochar on NO, N2O and N2 Production during Denitrification in Acid Soils.

    Directory of Open Access Journals (Sweden)

    Alfred Obia

    Full Text Available Biochar (BC application to soil suppresses emission of nitrous- (N2O and nitric oxide (NO, but the mechanisms are unclear. One of the most prominent features of BC is its alkalizing effect in soils, which may affect denitrification and its product stoichiometry directly or indirectly. We conducted laboratory experiments with anoxic slurries of acid Acrisols from Indonesia and Zambia and two contrasting BCs produced locally from rice husk and cacao shell. Dose-dependent responses of denitrification and gaseous products (NO, N2O and N2 were assessed by high-resolution gas kinetics and related to the alkalizing effect of the BCs. To delineate the pH effect from other BC effects, we removed part of the alkalinity by leaching the BCs with water and acid prior to incubation. Uncharred cacao shell and sodium hydroxide (NaOH were also included in the study. The untreated BCs suppressed N2O and NO and increased N2 production during denitrification, irrespective of the effect on denitrification rate. The extent of N2O and NO suppression was dose-dependent and increased with the alkalizing effect of the two BC types, which was strongest for cacao shell BC. Acid leaching of BC, which decreased its alkalizing effect, reduced or eliminated the ability of BC to suppress N2O and NO net production. Just like untreated BCs, NaOH reduced net production of N2O and NO while increasing that of N2. This confirms the importance of altered soil pH for denitrification product stoichiometry. Addition of uncharred cacao shell stimulated denitrification strongly due to availability of labile carbon but only minor effects on the product stoichiometry of denitrification were found, in accordance with its modest effect on soil pH. Our study indicates that stimulation of denitrification was mainly due to increases in labile carbon whereas change in product stoichiometry was mainly due to a change in soil pH.

  3. Impacts of soil moisture content on visual soil evaluation

    Science.gov (United States)

    Emmet-Booth, Jeremy; Forristal, Dermot; Fenton, Owen; Bondi, Giulia; Creamer, Rachel; Holden, Nick

    2017-04-01

    Visual Soil Examination and Evaluation (VSE) techniques offer tools for soil quality assessment. They involve the visual and tactile assessment of soil properties such as aggregate size and shape, porosity, redox morphology, soil colour and smell. An increasing body of research has demonstrated the reliability and utility of VSE techniques. However a number of limitations have been identified, including the potential impact of soil moisture variation during sampling. As part of a national survey of grassland soil quality in Ireland, an evaluation of the impact of soil moisture on two widely used VSE techniques was conducted. The techniques were Visual Evaluation of Soil Structure (VESS) (Guimarães et al., 2011) and Visual Soil Assessment (VSA) (Shepherd, 2009). Both generate summarising numeric scores that indicate soil structural quality, though employ different scoring mechanisms. The former requires the assessment of properties concurrently and the latter separately. Both methods were deployed on 20 sites across Ireland representing a range of soils. Additional samples were taken for soil volumetric water (θ) determination at 5-10 and 10-20 cm depth. No significant correlation was observed between θ 5-10 cm and either VSE technique. However, VESS scores were significantly related to θ 10-20 cm (rs = 0.40, sig = 0.02) while VSA scores were not (rs = -0.33, sig = 0.06). VESS and VSA scores can be grouped into quality classifications (good, moderate and poor). No significant mean difference was observed between θ 5-10 cm or θ 10-20 cm according to quality classification by either method. It was concluded that VESS scores may be affected by soil moisture variation while VSA appear unaffected. The different scoring mechanisms, where the separate assessment and scoring of individual properties employed by VSA, may limit soil moisture effects. However, moisture content appears not to affect overall structural quality classification by either method. References

  4. On the structural factors of soil humic matter related to soil water repellence in fire-affected soils

    Science.gov (United States)

    Almendros, G.; González-Vila, F. J.; González-Pérez, J. A.; Knicker, H.; De la Rosa, J. M.; Dettweiler, C.; Hernández, Z.

    2012-04-01

    In order to elucidate the impact of forest fires on physical and chemical properties of the soils as well as on the chemical composition of the soil organic matter, samples from two Mediterranean soils with contrasted characteristics and vegetation (O horizon, Lithic Leptosols under Quercus ilex and Pinus pinaster) and one agricultural soil (Ap horizon, Luvisol) were heated at 350 °C in laboratory conditions for three successive steps up to 600 s. The C- and N-depletion in the course of the heating showed small changes up to an oxidation time of 300 s. On the other side, and after 600 s, considerable C-losses (between 21% in the Luvisol and 50% in the Leptosols) were observed. The relatively low N-depletion ca. 4% (Luvisol) and 21% (Leptosol under pine) suggested preferential loss of C and the subsequent relative enrichment of nitrogen. Paralleling the progressive depletion of organic matter, the Leptosols showed a significant increase of both pH and electrical conductivity. The former change paralleled the rapid loss of carboxyl groups, whereas the latter point to the relative enrichment of ash with a bearing on the concentration of inorganic ions, which could be considered a positive effect for the post-fire vegetation. The quantitative and qualitative analyses by solid-state 13C NMR spectra of the humic fractions in the samples subjected to successive heating times indicate significant concentration of aromatic structures newly-formed in the course of the dehydration and cyclization of carbohydrates (accumulation of black carbon-type polycyclic aromatic structures), and probably lipids and peptides. The early decarboxylation, in addition to the depletion of O-alkyl hydrophilic constituents and further accumulation of secondary aromatic structures resulted in the dramatic increase in the soil water drop penetration time. It was confirmed that this enhancement of the soil hydrophobicity is not related to an increased concentration of soil free lipid, but is

  5. Free atmospheric CO2 enrichment increased above ground biomass but did not affect symbiotic N2-fixation and soil carbon dynamics in a mixed deciduous stand in Wales

    Directory of Open Access Journals (Sweden)

    A. R. Smith

    2011-02-01

    Full Text Available Through increases in net primary production (NPP, elevated CO2 is hypothesized to increase the amount of plant litter entering the soil. The fate of this extra carbon on the forest floor or in mineral soil is currently not clear. Moreover, increased rates of NPP can be maintained only if forests can escape nitrogen limitation. In a Free atmospheric CO2 Enrichment (FACE experiment near Bangor, Wales, 4 ambient and 4 elevated [CO2] plots were planted with patches of Betula pendula, Alnus glutinosa and Fagus sylvatica on a former arable field. After 4 years, biomass averaged for the 3 species was 5497 (se 270 g m−2 in ambient and 6450 (se 130 g m−2 in elevated [CO2] plots, a significant increase of 17% (P = 0.018. During that time, only a shallow L forest floor litter layer had formed due to intensive bioturbation. Total soil C and N contents increased irrespective of treatment and species as a result of afforestation. We could not detect an additional C sink in the soil, nor were soil C stabilization processes affected by elevated [CO2]. We observed a decrease of leaf N content in Betula and Alnus under elevated [CO2], while the soil C/N ratio decreased regardless of CO2 treatment. The ratio of N taken up from the soil and by N2-fixation in Alnus was not affected by elevated [CO2]. We infer that increased nitrogen use efficiency is the mechanism by which increased NPP is sustained under elevated [CO2] at this site.

  6. Interactive effects of soil acidity and fluoride on soil solution aluminium chemistry and barley (Hordeum vulgare L.) root growth

    International Nuclear Information System (INIS)

    Manoharan, V.; Loganathan, P.; Tillman, R.W.; Parfitt, R.L.

    2007-01-01

    A greenhouse study was conducted to determine if concentrations of fluoride (F), which would be added to acid soils via P fertilisers, were detrimental to barley root growth. Increasing rates of F additions to soil significantly increased the soil solution concentrations of aluminium (Al) and F irrespective of the initial adjusted soil pH, which ranged from 4.25 to 5.48. High rates of F addition severely restricted root growth; the effect was more pronounced in the strongly acidic soil. Speciation calculations demonstrated that increasing rates of F additions substantially increased the concentrations of Al-F complexes in the soil. Stepwise regression analysis showed that it was the combination of the activities of AlF 2 1+ and AlF 2+ complexes that primarily controlled barley root growth. The results suggested that continuous input of F to soils, and increased soil acidification, may become an F risk issue in the future. - Addition of high rates of fluoride to strongly acidic soils can reduce barley root growth due to the toxicity of aluminium-fluoride complexes formed in soil solution

  7. Global Trend Analysis of Multi-decade Soil Temperature Records Show Soils Resistant to Warming

    Science.gov (United States)

    Frey, S. D.; Jennings, K.

    2017-12-01

    Soil temperature is an important determinant of many subterranean ecological processes including plant growth, nutrient cycling, and carbon sequestration. Soils are expected to warm in response to increasing global surface temperatures; however, despite the importance of soil temperature to ecosystem processes, less attention has been given to examining changes in soil temperature over time. We collected long-term (> 20 years) soil temperature records from approximately 50 sites globally, many with multiple depths (5 - 100 cm), and examined temperature trends over the last few decades. For each site and depth we calculated annual summer means and conducted non-parametric Mann Kendall trend and Sen slope analysis to assess changes in summer soil temperature over the length of each time series. The mean summer soil temperature trend across all sites and depths was not significantly different than zero (mean = 0.004 °C year-1 ± 0.033 SD), suggesting that soils have not warmed over the observation period. Of the subset of sites that exhibit significant increases in temperature over time, site location, depth of measurement, time series length, and neither start nor end date seem to be related to trend strength. These results provide evidence that the thermal regime of soils may have a stronger buffering capacity than expected, having important implications for the global carbon cycle and feedbacks to climate change.

  8. Soil Penetration by Earthworms and Plant Roots--Mechanical Energetics of Bioturbation of Compacted Soils.

    Directory of Open Access Journals (Sweden)

    Siul Ruiz

    Full Text Available We quantify mechanical processes common to soil penetration by earthworms and growing plant roots, including the energetic requirements for soil plastic displacement. The basic mechanical model considers cavity expansion into a plastic wet soil involving wedging by root tips or earthworms via cone-like penetration followed by cavity expansion due to pressurized earthworm hydroskeleton or root radial growth. The mechanical stresses and resulting soil strains determine the mechanical energy required for bioturbation under different soil hydro-mechanical conditions for a realistic range of root/earthworm geometries. Modeling results suggest that higher soil water content and reduced clay content reduce the strain energy required for soil penetration. The critical earthworm or root pressure increases with increased diameter of root or earthworm, however, results are insensitive to the cone apex (shape of the tip. The invested mechanical energy per unit length increase with increasing earthworm and plant root diameters, whereas mechanical energy per unit of displaced soil volume decreases with larger diameters. The study provides a quantitative framework for estimating energy requirements for soil penetration work done by earthworms and plant roots, and delineates intrinsic and external mechanical limits for bioturbation processes. Estimated energy requirements for earthworm biopore networks are linked to consumption of soil organic matter and suggest that earthworm populations are likely to consume a significant fraction of ecosystem net primary production to sustain their subterranean activities.

  9. Molybdenum (Mo) increases endogenous phenolics, proline and photosynthetic pigments and the phytoremediation potential of the industrially important plant Ricinus communis L. for removal of cadmium from contaminated soil.

    Science.gov (United States)

    Hadi, Fazal; Ali, Nasir; Fuller, Michael Paul

    2016-10-01

    Cadmium (Cd) in agricultural soil negatively affects crops yield and compromises food safety. Remediation of polluted soil is necessary for the re-establishment of sustainable agriculture and to prevent hazards to human health and environmental pollution. Phytoremediation is a promising technology for decontamination of polluted soil. The present study investigated the effect of molybdenum (Mo) (0.5, 1.0 and 2.0 ppm) on endogenous production of total phenolics and free proline, plant biomass and photosynthetic pigments in Ricinus communis plants grown in Cd (25, 50 and 100 ppm) contaminated soils and the potential for Cd phytoextraction. Mo was applied via seed soaking, soil addition and foliar spray. Foliar sprays significantly increased plant biomass, Cd accumulation and bioconcentration. Phenolic concentrations showed significantly positive correlations with Cd accumulation in roots (R 2  = 0.793, 0.807 and 0.739) and leaves (R 2  = 0.707, 721 and 0.866). Similarly, proline was significantly positively correlated with Cd accumulation in roots (R 2  = 0.668, 0.694 and 0.673) and leaves (R 2  = 0.831, 0.964 and 0.930). Foliar application was found to be the most effective way to deliver Mo in terms of increase in plant growth, Cd accumulation and production of phenolics and proline.

  10. Interactive effects of soil acidity and fluoride on soil solution aluminium chemistry and barley (Hordeum vulgare L.) root growth.

    Science.gov (United States)

    Manoharan, V; Loganathan, P; Tillman, R W; Parfitt, R L

    2007-02-01

    A greenhouse study was conducted to determine if concentrations of fluoride (F), which would be added to acid soils via P fertilisers, were detrimental to barley root growth. Increasing rates of F additions to soil significantly increased the soil solution concentrations of aluminium (Al) and F irrespective of the initial adjusted soil pH, which ranged from 4.25 to 5.48. High rates of F addition severely restricted root growth; the effect was more pronounced in the strongly acidic soil. Speciation calculations demonstrated that increasing rates of F additions substantially increased the concentrations of Al-F complexes in the soil. Stepwise regression analysis showed that it was the combination of the activities of AlF2(1+) and AlF(2+) complexes that primarily controlled barley root growth. The results suggested that continuous input of F to soils, and increased soil acidification, may become an F risk issue in the future.

  11. SOIL N, P AND K CONCENTRATIONS AND RICE YIELD INCREASED DUE TO THE APPLICATION OF Azolla pinnata

    Directory of Open Access Journals (Sweden)

    A. Arivin Rivaie*

    2014-01-01

    Full Text Available Many studies showed that application of Azolla pinnata as biofertilizer improved soil fertility some agricultural crops, including rice, whereas farmers in Lampung consider that A. pinnata suppresses growth of rice seedlings, so they throw it field by raising irrigation water surface. Information on effects A. pinnata application on changes in nutrient availability and rice yield obtained from paddy fields of regions still rare. A study was carried out to investigate effects of different rates of A. pinnata on changes in N, P, K concentrations in paddy soils, N uptake, and rice yield. A well-irrigated paddy field was incorporated with A. pinnata, and then rice seedlings of Ciherang variety had been grown from June up to December 2009. Results: application of A. pinnata at dose of five t per ha increased concentration of N, P and K as well as rice yield. A. pinnata had a relatively high N content, ie 2.43 percent. Application of A. pinnata of 7.5 t per ha increased significantly available soil P, indicated that A. pinnata requires a fairly high P to grow optimally. Application of A. pinnata of 7.5 t per ha gave highest dry grain yield, suggests that application A. pinnata did not suppress rice yield, even use of A. pinnata as organic matter source will help to conserve fossil fuels and foreign exchange as well as will allow more paddy fields that can be fertilized by N.

  12. Rehabilitating acid soils for increasing crop productivity through low-cost liming material.

    Science.gov (United States)

    Bhat, Javid Ahmad; Kundu, Manik Chandra; Hazra, Gora Chand; Santra, Gour Hari; Mandal, Biswapati

    2010-09-15

    Productivity of red and lateritic soils is low because of their acidity and deficiencies in few essential nutrients viz., nitrogen, phosphorus, calcium, zinc, boron, molybdenum etc. We compared the effectiveness of basic slag, a low-cost liming material, with that of calcite as an ameliorant for these soils using mustard followed by rice as test crops. Experiments were conducted with three levels of each of basic slag and calcite along with a control on farmers' fields at 14 different locations. Influence of farmyard manure (FYM) and poultry manure (PM) on the effectiveness of the slag was also tested. On an average, basic slag performed better than calcite in increasing yields of both mustard and rice and left over higher amounts of available Ca, Si and Zn in residual soils. The slag also improved N, P, K and Ca nutrition of mustard and Si and Zn nutrition of rice with a favorable benefit:cost (B:C) ratio over the calcite (4.82 vs. 1.44). Effectiveness of the basic slag improved when it was applied in combination with FYM or PM (B:C, 5.83 and 6.27). Basic slag can, therefore, be advocated for use in the acidic red and lateritic soils for economically improving their productivity. Copyright 2010 Elsevier B.V. All rights reserved.

  13. Rehabilitating acid soils for increasing crop productivity through low-cost liming material

    International Nuclear Information System (INIS)

    Bhat, Javid Ahmad; Kundu, Manik Chandra; Hazra, Gora Chand; Santra, Gour Hari; Mandal, Biswapati

    2010-01-01

    Productivity of red and lateritic soils is low because of their acidity and deficiencies in few essential nutrients viz., nitrogen, phosphorus, calcium, zinc, boron, molybdenum etc. We compared the effectiveness of basic slag, a low-cost liming material, with that of calcite as an ameliorant for these soils using mustard followed by rice as test crops. Experiments were conducted with three levels of each of basic slag and calcite along with a control on farmers' fields at 14 different locations. Influence of farmyard manure (FYM) and poultry manure (PM) on the effectiveness of the slag was also tested. On an average, basic slag performed better than calcite in increasing yields of both mustard and rice and left over higher amounts of available Ca, Si and Zn in residual soils. The slag also improved N, P, K and Ca nutrition of mustard and Si and Zn nutrition of rice with a favorable benefit:cost (B:C) ratio over the calcite (4.82 vs. 1.44). Effectiveness of the basic slag improved when it was applied in combination with FYM or PM (B:C, 5.83 and 6.27). Basic slag can, therefore, be advocated for use in the acidic red and lateritic soils for economically improving their productivity.

  14. Rehabilitating acid soils for increasing crop productivity through low-cost liming material

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, Javid Ahmad [Directorate of Research, Bidhan Chandra Krishi Viswavidyalaya, Kalyani - 741 235, West Bengal (India); Kundu, Manik Chandra, E-mail: mckundu@rediffmail.com [Directorate of Research, Bidhan Chandra Krishi Viswavidyalaya, Kalyani - 741 235, West Bengal (India); Hazra, Gora Chand [Directorate of Research, Bidhan Chandra Krishi Viswavidyalaya, Kalyani - 741 235, West Bengal (India); Santra, Gour Hari [Department of Soil Science and Agril. Chemistry, Orissa University of Agriculture and Technology, Bhubaneswar - 751003, Orissa (India); Mandal, Biswapati [Directorate of Research, Bidhan Chandra Krishi Viswavidyalaya, Kalyani - 741 235, West Bengal (India)

    2010-09-15

    Productivity of red and lateritic soils is low because of their acidity and deficiencies in few essential nutrients viz., nitrogen, phosphorus, calcium, zinc, boron, molybdenum etc. We compared the effectiveness of basic slag, a low-cost liming material, with that of calcite as an ameliorant for these soils using mustard followed by rice as test crops. Experiments were conducted with three levels of each of basic slag and calcite along with a control on farmers' fields at 14 different locations. Influence of farmyard manure (FYM) and poultry manure (PM) on the effectiveness of the slag was also tested. On an average, basic slag performed better than calcite in increasing yields of both mustard and rice and left over higher amounts of available Ca, Si and Zn in residual soils. The slag also improved N, P, K and Ca nutrition of mustard and Si and Zn nutrition of rice with a favorable benefit:cost (B:C) ratio over the calcite (4.82 vs. 1.44). Effectiveness of the basic slag improved when it was applied in combination with FYM or PM (B:C, 5.83 and 6.27). Basic slag can, therefore, be advocated for use in the acidic red and lateritic soils for economically improving their productivity.

  15. The impact of a copper smelter on adjacent soil zinc and cadmium fractions and soil organic carbon

    Energy Technology Data Exchange (ETDEWEB)

    Liu Ling; Wu Longhua; Luo Yongming [Key Lab. of Soil Environment and Pollution Remediation, Chinese Academy of Sciences, NJ (China); Zhang Changbo [Shanghai Academy of Environmental Sciences, SH (China); Jiang Yugen; Qiu Xiya [Soils and Fertilisers Div., Fuyang City Agricultural Bureau, Hangzhou, ZJ (China)

    2010-07-15

    Purpose: We investigated the chemical fractions of Zn, Cd and Cu in soils collected from positions at different distances from a copper smelter and studied the relationships between distribution patterns of Zn, Cd and Cu, fractions and soil organic carbon (SOC), especially ''black carbon'' (BC), in contaminated soils. The relationships between soil particle size and concentrations of Zn and Cd in contaminated soil were also examined. Materials and methods: Soil samples were collected from field sites at different distances from the copper smelter, air-dried and passed through 0.25-mm and 0.149-mm nylon mesh sieves. The SOC and BC were determined. Aqua regia and sequentially extracted Zn, Cd and Cu fractions in soil and the different sizes of soil particles, and metal concentrations (Zn, Cd and Cu) in BC were also determined. Results and discussion: The soils were heavily contaminated by fly ash from the copper smelter. Concentrations of Zn, Cd and Cu in soil and SOC decreased with increasing distance from the smelter. Concentrations of Zn and Cd in the surface soil (0-15 cm) decreased from 27,017 to 892 mg kg{sup -1} and from 18.7 to 1.04 mg kg{sup -1}, respectively. Soil BC and concentrations of Zn, Cd and Cu in the BC fraction showed significant and positive relationships with the corresponding aqua regia metal concentrations in soil. Soil Zn and Cd occurred predominantly in the exchangeable and reducible fractions, but residual and oxidisable fractions of Cu that were not considered mobile or bioavailable were predominant (>60%). Concentrations of Zn and Cd in the soil particle size fractions tended to increase with decreasing particle size. Conclusions: The Cd and Zn and BC were all derived from the fly ash of the smelter. Concentrations of Zn and Cd and BC in the soil decreased significantly with increasing distance from the smelter. Zinc and Cd in contaminated soils increased as particle size decreased, and were mainly in highly available

  16. Soil quality in a cropland soil treated with wood ash containing charcoal

    Science.gov (United States)

    Omil, Beatriz; Balboa, Miguel A.; Fonturbel, M. Teresa; Gartzia-Bengoetxea, Nahia; Arias-González, Ander; Vega, Jose A.; Merino, Agustin

    2014-05-01

    The strategy of the European Union "Europe 2020" states that by 2020, 20% of final energy consumption must come from renewables. In this scenario, there is an increasing use of biomass utilization for energy production. Indeed, it is expected that the production of wood-ash will increase in coming years. Wood ash, a mixture of ash and charcoal, generated as a by-product of biomass combustion in power plants, can be applied to soil to improve the soil quality and crop production. Since the residue contains significant content of charcoal, the application of mixed wood ash may also improve the SOM content and soil quality in the long term, in soils degraded as a consequence of intensive management. The objective of this study was asses the changes in SOM quality and soil properties in a degraded soils treated with wood ash containing charcoal. The study was carried out in a field devoted to cereal crops during the last decades. The soil was acidic (pH 4.5) with a low SOC content (3 %) and fine texture. The experiment was based on a randomised block design with four replicates. Each block included the following four treatments: Control, 16 Mg fly wood ash ha-1, 16 Mg mixed wood ash ha-1 (16 Mg) and 32 Mg mixed wood ash ha-1 (32 Mg). The application was carried out once. The ash used in the study was obtained from a thermal power plant and was mainly derived from the combustion of Pinus radiata bark and branches. The wood ash is highly alkaline (pH= 10), contains 10 % of highly condensed black carbon (atomic H/C ratio solid state 13C CPMAS NMR and Differential Scanning Calorimetry (DSC). These techniques were applied in bulk samples and aggregates of different sizes. The changes in microbial activity were studied by analysis of microbial biomass C and basal respiration. The soil bacterial community was studied by the Biolog method. Several physical properties, such soil aggregate distribution, hydraulic conductivity and available water contente were also determined

  17. Benefits of biochar, compost and biochar–compost for soil quality, maize yield and greenhouse gas emissions in a tropical agricultural soil

    International Nuclear Information System (INIS)

    Agegnehu, Getachew; Bass, Adrian M.; Nelson, Paul N.; Bird, Michael I.

    2016-01-01

    Soil quality decline represents a significant constraint on the productivity and sustainability of agriculture in the tropics. In this study, the influence of biochar, compost and mixtures of the two on soil fertility, maize yield and greenhouse gas (GHG) emissions was investigated in a tropical Ferralsol. The treatments were: 1) control with business as usual fertilizer (F); 2) 10 t ha"−"1 biochar (B) + F; 3) 25 t ha"−"1 compost (Com) + F; 4) 2.5 t ha"−"1 B + 25 t ha"−"1 Com mixed on site + F; and 5) 25 t ha"−"1 co-composted biochar–compost (COMBI) + F. Total aboveground biomass and maize yield were significantly improved relative to the control for all organic amendments, with increases in grain yield between 10 and 29%. Some plant parameters such as leaf chlorophyll were significantly increased by the organic treatments. Significant differences were observed among treatments for the δ"1"5N and δ"1"3C contents of kernels. Soil physicochemical properties including soil water content (SWC), total soil organic carbon (SOC), total nitrogen (N), available phosphorus (P), nitrate-nitrogen (NO_3"− N), ammonium-nitrogen (NH_4"+-N), exchangeable cations and cation exchange capacity (CEC) were significantly increased by the organic amendments. Maize grain yield was correlated positively with total biomass, leaf chlorophyll, foliar N and P content, SOC and SWC. Emissions of CO_2 and N_2O were higher from the organic-amended soils than from the fertilizer-only control. However, N_2O emissions generally decreased over time for all treatments and emission from the biochar was lower compared to other treatments. Our study concludes that the biochar and biochar–compost-based soil management approaches can improve SOC, soil nutrient status and SWC, and maize yield and may help mitigate greenhouse gas emissions in certain systems. - Graphical abstract: Grain yield, cation exchange capacity (CEC), soil organic carbon (SOC), soil water content (SWC) and N_2O

  18. Benefits of biochar, compost and biochar–compost for soil quality, maize yield and greenhouse gas emissions in a tropical agricultural soil

    Energy Technology Data Exchange (ETDEWEB)

    Agegnehu, Getachew [College of Science, Technology and Engineering, Centre for Tropical Environmental and Sustainability Science, James Cook University, PO Box 6811, Cairns, Queensland 4870 (Australia); Bass, Adrian M. [Hawkesbury Institute for the Environment, University of Western Sydney, Science Road, Richmond, New South Wales 2753 (Australia); Nelson, Paul N.; Bird, Michael I. [College of Science, Technology and Engineering, Centre for Tropical Environmental and Sustainability Science, James Cook University, PO Box 6811, Cairns, Queensland 4870 (Australia)

    2016-02-01

    Soil quality decline represents a significant constraint on the productivity and sustainability of agriculture in the tropics. In this study, the influence of biochar, compost and mixtures of the two on soil fertility, maize yield and greenhouse gas (GHG) emissions was investigated in a tropical Ferralsol. The treatments were: 1) control with business as usual fertilizer (F); 2) 10 t ha{sup −1} biochar (B) + F; 3) 25 t ha{sup −1} compost (Com) + F; 4) 2.5 t ha{sup −1} B + 25 t ha{sup −1} Com mixed on site + F; and 5) 25 t ha{sup −1} co-composted biochar–compost (COMBI) + F. Total aboveground biomass and maize yield were significantly improved relative to the control for all organic amendments, with increases in grain yield between 10 and 29%. Some plant parameters such as leaf chlorophyll were significantly increased by the organic treatments. Significant differences were observed among treatments for the δ{sup 15}N and δ{sup 13}C contents of kernels. Soil physicochemical properties including soil water content (SWC), total soil organic carbon (SOC), total nitrogen (N), available phosphorus (P), nitrate-nitrogen (NO{sub 3}{sup −} N), ammonium-nitrogen (NH{sub 4}{sup +}-N), exchangeable cations and cation exchange capacity (CEC) were significantly increased by the organic amendments. Maize grain yield was correlated positively with total biomass, leaf chlorophyll, foliar N and P content, SOC and SWC. Emissions of CO{sub 2} and N{sub 2}O were higher from the organic-amended soils than from the fertilizer-only control. However, N{sub 2}O emissions generally decreased over time for all treatments and emission from the biochar was lower compared to other treatments. Our study concludes that the biochar and biochar–compost-based soil management approaches can improve SOC, soil nutrient status and SWC, and maize yield and may help mitigate greenhouse gas emissions in certain systems. - Graphical abstract: Grain yield, cation exchange capacity (CEC), soil

  19. [Cd Runoff Load and Soil Profile Movement After Implementation of Some Typical Contaminated Agricultural Soil Remediation Strategies].

    Science.gov (United States)

    Liu, Xiao-li; Zeng, Zhao-xia; Tie, Bai-qing; Chen, Qiu-wen; Wei, Xiang-dong

    2016-02-15

    Owing to the strong ability to immobilize and hyperaccumulate some toxic heavy metals in contaminated soils, the biochar, lime and such as hyperaccumulator ramie received increasing interests from crops and environment safety in recent years. Outdoor pot experiment was conducted to compare the impacts of lime and biochar addition in paddy rice treatment, hyperaccumulator ramie and ramie combined with EDTA of plant Phytoremediation methods on soil available Cd dynamics in rainfall runoff and the mobility along soil profile, under both natural acid precipitation and acid soil conditions. The results showed that, biochar addition at a 2% mass ratio application amount significantly increased soil pH, while ramie with EDTA application obviously decreased soil pH compared to ramie monoculture. Within the same rainfall events, water soluble Cd concentration in surface runoff of ramie treatments was significantly higher than those of waterlogged rice treatments, and Cd concentration in runoff was obviously increased after EDTA addition, whereas lime at a 0.3% mass ratio application amount as additive had no obvious impact on soil pH and Cd speciation change, which may be due to the low application amount. During the whole experimental period , water soluble Cd concentration of rainfall runoff in spring was higher than that in summer, showing the same seasonal characteristics in all treatments. Biochar addition could significantly decrease available Cd content in 0-20 cm soil layer and with certain preferable persistency effects, whereas EDTA addition treatment obviously increased available Cd of 0-20 cm soil layer compared to other treatments, and obvious Cd element activation phenomenon in 20-40 cm soil layer was observed after EDTA addition. In conclusion, lime and biochar as environmental and friendly alkaline Cd immobilization materials showed lower environment risk to surface and ground receiving water, but attention should be paid to phytoremediation enhanced with

  20. Grazing exclusion increases soil CO2 emission during the growing season in alpine meadows on the Tibetan Plateau

    Science.gov (United States)

    Guo, Na; Wang, Aidong; Allan Degen, A.; Deng, Bin; Shang, Zhanhuan; Ding, Luming; Long, Ruijun

    2018-02-01

    Soil CO2 emission is a key part of the terrestrial carbon cycle. Grazing exclusion by fencing is often considered a beneficial grassland management option to restore degraded grassland, but its effect on soil CO2 emission on the northeastern Tibetan Plateau is equivocal and is the subject of this study. Using a closed static chamber, we measured diurnal soil CO2 flux weekly from July, 2008, to April, 2009, in response to grazing and grazing exclusion in the alpine meadow and alpine shrub meadow. Concomitantly, soil temperature was measured at depths of 5 cm, 10 cm, 15 cm and 20 cm with digital temperature sensors. It emerged that: 1) non-grazed grasslands emitted more soil CO2 than grazed grasslands over the growing season; 2) the alpine shrub meadow emitted more soil CO2 than the alpine meadow; the annual cumulative soil CO2 emissions of alpine meadow and alpine shrub meadow were 241.5-326.5 g C/m2 and 429.0-512.5 g C/m2, respectively; 3) seasonal patterns were evident with more soil CO2 flux in the growing than in the non-growing season; and 4) the diurnal soil CO2 flux exhibited a single peak across all sampling sites. In addition, soil CO2 flux was correlated positively with soil temperature at 5 cm, but not at the other depths. We concluded that grazing exclusion enhanced soil CO2 emission over the growing season, and decreased carbon sequestration of alpine meadow and alpine shrub meadow on the northeastern Tibetan Plateau. Since an increase in soil temperature increased soil CO2 flux, global warming could have an effect on soil CO2 emission in the future.

  1. Abundant and stable char residues in soils: implications for soil fertility and carbon sequestration.

    Science.gov (United States)

    Mao, J-D; Johnson, R L; Lehmann, J; Olk, D C; Neves, E G; Thompson, M L; Schmidt-Rohr, K

    2012-09-04

    Large-scale soil application of biochar may enhance soil fertility, increasing crop production for the growing human population, while also sequestering atmospheric carbon. But reaching these beneficial outcomes requires an understanding of the relationships among biochar's structure, stability, and contribution to soil fertility. Using quantitative (13)C nuclear magnetic resonance (NMR) spectroscopy, we show that Terra Preta soils (fertile anthropogenic dark earths in Amazonia that were enriched with char >800 years ago) consist predominantly of char residues composed of ~6 fused aromatic rings substituted by COO(-) groups that significantly increase the soils' cation-exchange capacity and thus the retention of plant nutrients. We also show that highly productive, grassland-derived soils in the U.S. (Mollisols) contain char (generated by presettlement fires) that is structurally comparable to char in the Terra Preta soils and much more abundant than previously thought (~40-50% of organic C). Our findings indicate that these oxidized char residues represent a particularly stable, abundant, and fertility-enhancing form of soil organic matter.

  2. EFFORT INCREASING STARCH’S CONTENT OF ARROWROOT WITH BOKHASI AND SOIL PROCESSING TREATMENT

    Directory of Open Access Journals (Sweden)

    Bambang Rudianto W

    2013-01-01

    Full Text Available Objective this experiment knows: (1 Effect bokashi on growth and yield arrowroot,(2 optimal dosage bokashi to increase arrowroot production,(3 effect planting depth on growth and yield arrowroot , and (4 interactions between planting depth and bokashi's manure dose on arrowroot. Research carried at field experimental Agriculture Faculty of Jenderal Soedirman University, October 2010 until March 2011. Experiment used inceptisol soil and 110 meters above sea level. Experimental design was Completely Randomized Block Design with four replicates, tried factors were planting depth and bokashi's fertilizer addition. Result: bokashi increase starch's content of arrowroot from 17,38 percent to 19,63 percent. Addition of bokashi at three percent of organic matter content soil, indicated by starch content of 19,634 percent. Planting depth at 20 cm affected increasing tubber volume per plant, tubber fresh weight, and production per extends, meanwhile planting depth at 30 cm affected increasing starch's contents tubber arrowroot. Interaction between planting depth and bokashi's fertilizer on starch's content yielded 19,898 percent at addition of bokashi at amount of three percent and planting depth 30 cm.

  3. Long-term application of bioorganic fertilizers improved soil biochemical properties and microbial communities of an apple orchard soil

    Directory of Open Access Journals (Sweden)

    Wang Lei

    2016-11-01

    Full Text Available Soil biochemical properties and microbial communities are usually considered as important indicators of soil health because of their association with plant nutrition. In this study, we investigated the impact of long-term application of bioorganic fertilizer (BOF on soil biochemical properties and microbial communities in the apple orchard soil of the Loess Plateau. The experiment included three treatments: (1 control without fertilization (CK; (2 chemical fertilizer application (CF; and (3 bioorganic fertilizer application (BOF. The high throughput sequencing was used to examine the bacterial and fungal communities in apple orchard soil. The results showed that the BOF treatment significantly increased the apple yield during the experimental time (2009-2015. The application of BOF significantly increased the activities of catalase and invertase compared to those in CK and CF treatments. The high throughput sequencing data showed that the application of BOF changed the microbial community composition of all soil depths considered (0-20cm, 20-40cm, and 40-60cm, e.g., the relative abundance of bio-control bacteria (Xanthomonadales, Lysobacter, Pseudomonas and Bacillus, Proteobacteria, Bacteroidetes, Ohtaekwangia, Ilyonectria and Lecanicillium was increased while that of Acidobacteria, Chloroflexi, Gp4, Gp6 and Sphaerobacter was decreased. The increase in apple yield after the application of BOF might be due to increase in organic matter, total nitrogen and catalase and invertase activities of soil and change in the bacterial community composition by enriching Bacillus, Pseudomonas, Lysobacter and Ohtaekwangia. These results further enhance the understanding on how BOFs alter soil microbial community composition to stimulate soil productivity.

  4. Soil physical characteristics after EDTA washing and amendment with inorganic and organic additives

    International Nuclear Information System (INIS)

    Zupanc, Vesna; Kastelec, Damijana; Lestan, Domen; Grcman, Helena

    2014-01-01

    Soil washing has been established as suitable remediation technology, with most research focused on metal removing efficiency and toxic effect on plants, less on the influence on soil physical characteristics, which was the focus of this study. In soil column experiment highly contaminated soil and soil washed with EDTA, mixed with additives (gypsum, hydrogel, manure, peat) were tested. White clover was used as a soil cover. Yield, metal concentration in soil and plant, aggregate fractionation and stability, saturated hydraulic conductivity and soil water retention of the soil were measured. Soil washing decreased metal concentration in soil and plants, but yield of white clover on remediated soil was significantly lower compared to the original soil. Significant differences in water retention characteristics, aggregate fractionation and stability between original and remediated soil have been determined. Gypsum, hydrogel and peat increased plant available water, manure and peat increased yield on remediated soil. -- Highlights: • Clover yield on washed soil was significantly lower than on original soil. • Organic additives increased yield on remediated soils. • Soil washing changed soil water retention and soil structure. • Hydrogen, gypsum and peat increased plant available water of remediated soil. -- The study critically examines yield, plant metal uptake and possible changes in soil physical characteristics as a consequence of soil washing procedure for metal pollution remediation

  5. Understanding and Enhancing Soil Biological Health: The Solution for Reversing Soil Degradation

    Directory of Open Access Journals (Sweden)

    R. Michael Lehman

    2015-01-01

    Full Text Available Our objective is to provide an optimistic strategy for reversing soil degradation by increasing public and private research efforts to understand the role of soil biology, particularly microbiology, on the health of our world’s soils. We begin by defining soil quality/soil health (which we consider to be interchangeable terms, characterizing healthy soil resources, and relating the significance of soil health to agroecosystems and their functions. We examine how soil biology influences soil health and how biological properties and processes contribute to sustainability of agriculture and ecosystem services. We continue by examining what can be done to manipulate soil biology to: (i increase nutrient availability for production of high yielding, high quality crops; (ii protect crops from pests, pathogens, weeds; and (iii manage other factors limiting production, provision of ecosystem services, and resilience to stresses like droughts. Next we look to the future by asking what needs to be known about soil biology that is not currently recognized or fully understood and how these needs could be addressed using emerging research tools. We conclude, based on our perceptions of how new knowledge regarding soil biology will help make agriculture more sustainable and productive, by recommending research emphases that should receive first priority through enhanced public and private research in order to reverse the trajectory toward global soil degradation.

  6. Variation in soil aggregate-size distribution affects the dissipation of polycyclic aromatic hydrocarbons in long-term field-contaminated soils.

    Science.gov (United States)

    Wei, Ran; Ni, Jinzhi; Chen, Weifeng; Yang, Yusheng

    2017-10-01

    Soil organic matter (SOM) is the main adsorbent for polycyclic aromatic hydrocarbons (PAHs) and the principal aggregating agent for soil aggregation that can affect PAH bioavailability and bioaccessibility in soils. The objective of this study was to analyze the relationship between PAH dissipation and variation in soil aggregate-size distribution in two field-contaminated soils with different soil organic C (SOC) content (Anthrosols, 1.41% SOC; Phaeozems, 8.51% SOC) in phytoremediation with alfalfa. The results showed that there were significant reductions of 10.2 and 15.4% of the total PAHs in unplanted and planted treatments, respectively, for Anthrosols. However, there was no significant reduction of total PAHs in either unplanted or planted treatment for Phaeozems. For Anthrosols, mass percentages of coarse sand and fine sand were significantly reduced while coarse silt and fine silt were significantly increased for the planted soil compared to the initial soil (p soil was slightly reduced. The main reason for the dissipation of PAHs in Anthrosols could be that macroaggregates were broken into microaggregates, which made some trapped PAHs become bioaccessible to soil microorganisms.

  7. Rhizobial inoculation increases soil microbial functioning and gum arabic production of 13-years old Senegalia senegal (L. Britton, trees in the North part of Senegal

    Directory of Open Access Journals (Sweden)

    Dioumacor FALL

    2016-09-01

    Full Text Available Abstract Rhizobial inoculation has been widely used in controlled conditions as a substitute for chemical fertilizers to increase plants growth and productivity. However, very little is known about such effects on mature trees in natural habitats. In this study, we investigated the effect of rhizobial inoculation on soil total microbial biomass, mineral nitrogen content, potential CO2 respiration, fluorescein diacetate (FDA, acid phosphatase activities and gum arabic production by 13-years old Senegalia senegal (Syn. Acacia senegal under natural conditions in the north part of Senegal during two consecutive years. Rhizobial inoculation was performed at the beginning of the rainy season (July for both years with a cocktail of four strains (CIRADF 300, CIRADF 301, CIRADF 302 and CIRADF 303. Rhizospheric soils were collected in both dry and rainy seasons to a depth of 0-25 cm under uninoculated (UIN and inoculated (IN trees. Trees were tapped in November (beginning of dry season using traditional tools. Gum arabic was harvested every 15 days from December to March. The results obtained from both years demonstrated that rhizobial inoculation increased significantly the percentage of trees producing gum arabic, gum arabic production per tree, soil microbial biomass, FDA and acid phosphatase activities. However, there was no significant effect on C mineralization and mineral nitrogen (N content. Gum arabic production was positively correlated to rainfall, soil microbial biomass and mineral nitrogen content. Our results showed a positive effect of rhizobial inoculation on soil microbial functioning and gum arabic production by mature S. senegal trees. These important findings deserve to be conducted in several contrasting sites in order to improve gum arabic production and contribute to increase rural population incomes.

  8. Rhizobial Inoculation Increases Soil Microbial Functioning and Gum Arabic Production of 13-Year-Old Senegalia senegal (L.) Britton, Trees in the North Part of Senegal.

    Science.gov (United States)

    Fall, Dioumacor; Bakhoum, Niokhor; Nourou Sall, Saïdou; Zoubeirou, Alzouma Mayaki; Sylla, Samba N; Diouf, Diegane

    2016-01-01

    Rhizobial inoculation has been widely used in controlled conditions as a substitute for chemical fertilizers to increase plants growth and productivity. However, very little is known about such effects on mature trees in natural habitats. In this study, we investigated the effect of rhizobial inoculation on soil total microbial biomass, mineral nitrogen content, potential CO2 respiration, fluorescein diacetate (FDA), acid phosphatase activities, and gum arabic production by 13-year-old Senegalia senegal (synonym: Acacia senegal) under natural conditions in the north part of Senegal during two consecutive years. Rhizobial inoculation was performed at the beginning of the rainy season (July) for both years with a cocktail of four strains (CIRADF 300, CIRADF 301, CIRADF 302, and CIRADF 303). Rhizospheric soils were collected in both dry and rainy seasons to a depth of 0-25 cm under uninoculated and inoculated trees. Trees were tapped in November (beginning of dry season) using traditional tools. Gum arabic was harvested every 15 days from December to March. The results obtained from both years demonstrated that rhizobial inoculation increased significantly the percentage of trees producing gum arabic, gum arabic production per tree, soil microbial biomass, FDA, and acid phosphatase activities. However, there was no significant effect on C mineralization and mineral nitrogen (N) content. Gum arabic production was positively correlated to rainfall, soil microbial biomass, and mineral nitrogen content. Our results showed a positive effect of rhizobial inoculation on soil microbial functioning and gum arabic production by mature S. senegal trees. These important findings deserve to be conducted in several contrasting sites in order to improve gum arabic production and contribute to increase rural population incomes.

  9. Relationships between soil properties and community structure of soil macroinvertebrates in oak-history forests along an acidic deposition gradient

    Energy Technology Data Exchange (ETDEWEB)

    Kuperman, R.G. [Argonne National Lab., IL (United States). Environmental Assessment Div.

    1996-02-01

    Soil macroinvertebrate communities were studied in ecologically analogous oak-hickory forests across a three-state atmospheric pollution gradient in Illinois, Indiana, and Ohio. The goal was to investigate changes in the community structure of soil fauna in study sites receiving different amounts of acidic deposition for several decades and the possible relationships between these changes and physico-chemical properties of soil. The study revealed significant differences in the numbers of soil animals among the three study sites. The sharply differentiated pattern of soil macroinvertebrate fauna seems closely linked to soil chemistry. Significant correlations of the abundance of soil macroinvertebrates with soil parameters suggest that their populations could have been affected by acidic deposition in the region. Abundance of total soil macroinvertebrates decreased with the increased cumulative loading of acidic deposition. Among the groups most sensitive to deposition were: earthworms gastropods, dipteran larvae, termites, and predatory beetles. The results of the study support the hypothesis that chronic long-term acidic deposition could aversely affect the soil decomposer community which could cause lower organic matter turnover rates leading to an increase in soil organic matter content in high deposition sites.

  10. 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.

  11. Transfer of Nickel from Polluted Soil to Pisum sativum L. and Raphanus sativus L. under Composted Green Amendment and Native Soil Microbes

    Directory of Open Access Journals (Sweden)

    Nafady Nivien Allam

    2017-08-01

    Full Text Available The effect of compost, inoculation with native soil microbes and their residual effects on bioavailability of nickel by peas (Pisum sativum L. and radish (Raphanus sativus L. grown on polluted soil were investigated in pot experiments. Plants were amendment with different compost levels (0, 0.2, 0.4, 0.6% of soil dry weight and inoculated with different native soil microbes (4 fungal species, one bacterial species, 4 species of arbuscular mycorrhizal fungi isolated from the polluted soil under study. Significant increases in the biomass of pea and radish plants were observed as a result of amendment application and their residual effects. The mycorrhizal dependency (MD of pea plants was lower than of radish plants. The highest reductions of Ni levels in both plants were observed by the simultaneous applications of compost with microbes or mycorrhizal fungi to polluted soils. Soil pH increased significantly (p < 0.05 as a result of applying native microbes especially with arbuscular mycorrhizal fungi (AMF alone or combined with compost. The DTPA extractability of soil Ni was significantly decreased with increasing soil pH (p < 0.05. The minimum transfer factor of Ni from polluted soil were 0.067 and 0.089 for pea and radish plants, respectively which were attained as a result of applying compost (0.6% of soil weight inoculated with mycorrhizal fungi. From the results, we can conclude that the use of compost and native soil microbes as a soil remediate could be an effective strategy for soil remediation.

  12. Effects of soil management techniques on soil water erosion in apricot orchards.

    Science.gov (United States)

    Keesstra, Saskia; Pereira, Paulo; Novara, Agata; Brevik, Eric C; Azorin-Molina, Cesar; Parras-Alcántara, Luis; Jordán, Antonio; Cerdà, Artemi

    2016-05-01

    Soil erosion is extreme in Mediterranean orchards due to management impact, high rainfall intensities, steep slopes and erodible parent material. Vall d'Albaida is a traditional fruit production area which, due to the Mediterranean climate and marly soils, produces sweet fruits. However, these highly productive soils are left bare under the prevailing land management and marly soils are vulnerable to soil water erosion when left bare. In this paper we study the impact of different agricultural land management strategies on soil properties (bulk density, soil organic matter, soil moisture), soil water erosion and runoff, by means of simulated rainfall experiments and soil analyses. Three representative land managements (tillage/herbicide/covered with vegetation) were selected, where 20 paired plots (60 plots) were established to determine soil losses and runoff. The simulated rainfall was carried out at 55mmh(-1) in the summer of 2013 (soil moisture) for one hour on 0.25m(2) circular plots. The results showed that vegetation cover, soil moisture and organic matter were significantly higher in covered plots than in tilled and herbicide treated plots. However, runoff coefficient, total runoff, sediment yield and soil erosion were significantly higher in herbicide treated plots compared to the others. Runoff sediment concentration was significantly higher in tilled plots. The lowest values were identified in covered plots. Overall, tillage, but especially herbicide treatment, decreased vegetation cover, soil moisture, soil organic matter, and increased bulk density, runoff coefficient, total runoff, sediment yield and soil erosion. Soil erosion was extremely high in herbicide plots with 0.91Mgha(-1)h(-1) of soil lost; in the tilled fields erosion rates were lower with 0.51Mgha(-1)h(-1). Covered soil showed an erosion rate of 0.02Mgha(-1)h(-1). These results showed that agricultural management influenced water and sediment dynamics and that tillage and herbicide

  13. Shifts in pore connectivity from precipitation versus groundwater rewetting increases soil carbon loss after drought

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Ashly P.; Bond-Lamberty, Benjamin; Benscoter, Brian W.; Tfaily, Malak M.; Hinkle, Ross; Liu, Chongxuan; Bailey, Vanessa L.

    2017-11-06

    Droughts and other extreme precipitation events are predicted to increase in intensity, duration and extent, with uncertain implications for terrestrial carbon (C) sequestration. Soil wetting from above (precipitation) results in a characteristically different pattern of pore-filling than wetting from below (groundwater), with larger, well-connected pores filling before finer pore spaces, unlike groundwater rise in which capillary forces saturate the finest pores first. Here we demonstrate that pore-scale wetting patterns interact with antecedent soil moisture conditions to alter pore-, core- and field-scale C dynamics. Drought legacy and wetting direction are perhaps more important determinants of short-term C mineralization than current soil moisture content in these soils. Our results highlight that microbial access to C is not solely limited by physical protection, but also by drought or wetting-induced shifts in hydrologic connectivity. We argue that models should treat soil moisture within a three-dimensional framework emphasizing hydrologic conduits for C and resource diffusion.

  14. [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.

  15. Soil fungi as indicators of pesticide soil pollution

    Directory of Open Access Journals (Sweden)

    Mandić Leka

    2005-01-01

    Full Text Available Soil fungi, with their pronounced enzymic activity and high osmotic potential, represent a significant indicator of negative effects of different pesticides on the agroecosystem as a whole. In that respect, a trial was set up on the alluvium soil type with the aim to investigate the effect of different herbicides (Simazine, Napropamid, Paraquat, fungicides (Captan and Mancozeb and insecticides (Fenitrothion and Dimethoate on a number of soil fungi under apple trees. The number of soil fungi was determined during four growing seasons by an indirect method of dilution addition on the Czapek agar. The study results indicate that the fungi belong to the group of microorganisms that, after an initial sensible response to the presence of pesticides in the soil, very rapidly establish normal metabolism enabling them even to increase their number. The fungicides and insecticides applied were found to be particularly effective in that respect.

  16. Effect of some soil amendments on soil properties and plant growth in Southern Thailand acid upland soil

    Directory of Open Access Journals (Sweden)

    Onthong, C.

    2007-01-01

    Full Text Available One of the major factors limiting plant growth is acid soil. In general lime is used for soil amendment in acid soil. However, It has been reported that gypsum or phosphogypsum can be used for ameliorating soilacidity. Pot experiment was conducted to study the effects of lime, phosphogypsum and kieserite on soil properties and plant growth in Kho Hong soil series (coarse loamy, kaolinitic,isohyperthermic, TypicKandiudults which was considered as acid upland soil (pH 5.07. Sweet corn variety INSEE 2 was used as the test crop. The experiment was a completely randomized design with 4 replications and 19 treatments asfollow : unamended, application of hydrated lime and dolomite to raise soil pH at 5.5, application of hydrated lime and dolomite combined with phosphogypsum at the rate that can supply calcium 0.25, 0.50,0.75 and 1 time of both limes, application of hydrated lime and dolomite combined with kieserite at the rate 0.25, 0.50,0.75 and 1 times of sulfur requirement for corn (40 kg S ha-1. The result showed that shoot and root dry weights of corn were increased when lime materials, phosphogypsum and kieserite were applied and the drymatter weights were increased according to the increasing of phosphogypsum and kieserite. The maximum shoot dry weight (18.98 g pot-1 was obtained when 1 times of kieserite was supplied with dolomite and wassignificantly (P<0.01 higher than those of the unamended treatment, only hydrated lime and dolomite treatments, which had dry weights of 12.64, 15.18 and 15.67 g pot-1 respectively. Phosphorus and K uptakewere not significantly different in all treatments and the lowest uptake of N, Ca, Mg and S was obtained in the unamended treatment. The maximum uptake of N (512.10 mg pot-1 was found when 0.5 times ofphosphogypsum was applied together with dolomite. Calcium and Mg uptake was likely to increase according to the increasing rate of soil amendment application. Highest uptake of Ca (42.51 mg pot-1 was obtainedwhen

  17. Quantifying the heterogeneity of soil compaction, physical soil properties and soil moisture across multiple spatial scales

    Science.gov (United States)

    Coates, Victoria; Pattison, Ian; Sander, Graham

    2016-04-01

    England's rural landscape is dominated by pastoral agriculture, with 40% of land cover classified as either improved or semi-natural grassland according to the Land Cover Map 2007. Since the Second World War the intensification of agriculture has resulted in greater levels of soil compaction, associated with higher stocking densities in fields. Locally compaction has led to loss of soil storage and an increased in levels of ponding in fields. At the catchment scale soil compaction has been hypothesised to contribute to increased flood risk. Previous research (Pattison, 2011) on a 40km2 catchment (Dacre Beck, Lake District, UK) has shown that when soil characteristics are homogeneously parameterised in a hydrological model, downstream peak discharges can be 65% higher for a heavy compacted soil than for a lightly compacted soil. However, at the catchment scale there is likely to be a significant amount of variability in compaction levels within and between fields, due to multiple controlling factors. This research focusses in on one specific type of land use (permanent pasture with cattle grazing) and areas of activity within the field (feeding area, field gate, tree shelter, open field area). The aim was to determine if the soil characteristics and soil compaction levels are homogeneous in the four areas of the field. Also, to determine if these levels stayed the same over the course of the year, or if there were differences at the end of the dry (October) and wet (April) periods. Field experiments were conducted in the River Skell catchment, in Yorkshire, UK, which has an area of 120km2. The dynamic cone penetrometer was used to determine the structural properties of the soil, soil samples were collected to assess the bulk density, organic matter content and permeability in the laboratory and the Hydrosense II was used to determine the soil moisture content in the topsoil. Penetration results show that the tree shelter is the most compacted and the open field area

  18. The grey areas in soil pollution risk mapping : The distinction between cases of soil pollution and increased background levels

    NARCIS (Netherlands)

    Gaast, N. van der; Leenaers, H.; Zegwaard, J.

    1998-01-01

    The progress of soil clean up in the Netherlands is severely hindered by the lack of common agreement on how to describe the grey areas of increased background levels of pollutants. In this study practical methods are proposed in which background levels are described as distribution functions within

  19. A long-term soil structure observatory for post-compaction soil structure evolution: design and initial soil structure recovery observations

    Science.gov (United States)

    Keller, Thomas; Colombi, Tino; Ruiz, Siul; Grahm, Lina; Reiser, René; Rek, Jan; Oberholzer, Hans-Rudolf; Schymanski, Stanislaus; Walter, Achim; Or, Dani

    2016-04-01

    to about half a metre, decreased gas and water transport functions (air permeability, gas diffusivity, saturated hydraulic conductivity), and increased mechanical impedance. Water infiltration at the soil surface was initially reduced by three orders of magnitude, but significantly recovered within a year. However, within the soil profile, recovery of transport properties is much smaller. Air permeability tended to recover more than gas diffusivity, suggesting that initial post-compaction recovery is initiated by new macropores (e.g. biopores). Tillage recovered topsoil bulk density but not topsoil transport functions. Compaction changed grass species composition in PG, and significantly reduced grass biomass in PG and crop yields in NT and CT.

  20. Fast changes in seasonal forest communities due to soil moisture increase after damming

    Directory of Open Access Journals (Sweden)

    Vagner Santiago do Vale

    2013-12-01

    Full Text Available Local changes caused by dams can have drastic consequences for ecosystems, not only because they change the water regime but also the modification on lakeshore areas. Thus, this work aimed to determine the changes in soil moisture after damming, to understand the consequences of this modification on the arboreal community of dry forests, some of the most endangered systems on the planet. We studied these changes in soil moisture and the arboreal community in three dry forests in the Araguari River Basin, after two dams construction in 2005 and 2006, and the potential effects on these forests. For this, plots of 20m x10m were distributed close to the impoundment margin and perpendicular to the dam margin in two deciduous dry forests and one semi-deciduous dry forest located in Southeastern Brazil, totaling 3.6ha sampled. Besides, soil analysis were undertaken before and after impoundment at three different depths 0-10, 20-30 and 40-50cm. A tree minimum DBH of 4.77cm community inventory was made before T0 and at two T2 and four T4 years after damming. Annual dynamic rates of all communities were calculated, and statistical tests were used to determine changes in soil moisture and tree communities. The analyses confirmed soil moisture increases in all forests, especially during the dry season and at sites closer to the reservoir; besides, an increase in basal area due to the fast growth of many trees was observed. The highest turnover occurred in the first two years after impoundment, mainly due to the higher tree mortality especially of those closer to the dam margin. All forests showed reductions in dynamic rates for subsequent years T2-T4, indicating that these forests tended to stabilize after a strong initial impact. The modifications were more extensive in the deciduous forests, probably because the dry period resulted more rigorous in these forests when compared to semideciduous forest. The new shorelines created by damming increased soil

  1. Effects of inorganic and organic amendment on soil chemical properties, enzyme activities, microbial community and soil quality in yellow clayey soil.

    Directory of Open Access Journals (Sweden)

    Zhanjun Liu

    Full Text Available Understanding the effects of external organic and inorganic components on soil fertility and quality is essential for improving low-yielding soils. We conducted a field study over two consecutive rice growing seasons to investigate the effect of applying chemical fertilizer (NPK, NPK plus green manure (NPKG, NPK plus pig manure (NPKM, and NPK plus straw (NPKS on the soil nutrient status, enzyme activities involved in C, N, P, and S cycling, microbial community and rice yields of yellow clayey soil. Results showed that the fertilized treatments significantly improved rice yields over the first three experimental seasons. Compared with the NPK treatment, organic amendments produced more favorable effects on soil productivity. Notably, the NPKM treatment exhibited the highest levels of nutrient availability, microbial biomass carbon (MBC, activities of most enzymes and the microbial community. This resulted in the highest soil quality index (SQI and rice yield, indicating better soil fertility and quality. Significant differences in enzyme activities and the microbial community were observed among the treatments, and redundancy analysis showed that MBC and available N were the key determinants affecting the soil enzyme activities and microbial community. The SQI score of the non-fertilized control (0.72 was comparable to that of the NPK (0.77, NPKG (0.81 and NPKS (0.79 treatments but significantly lower compared with NPKM (0.85. The significant correlation between rice yield and SQI suggests that SQI can be a useful to quantify soil quality changes caused by different agricultural management practices. The results indicate that application of NPK plus pig manure is the preferred option to enhance SOC accumulation, improve soil fertility and quality, and increase rice yield in yellow clayey soil.

  2. Effects of imidacloprid on soil microbial communities in different saline soils.

    Science.gov (United States)

    Zhang, Qingming; Xue, Changhui; Wang, Caixia

    2015-12-01

    The effects of imidacloprid in the soil environment are a worldwide concern. However, the impact of imidacloprid on soil microorganisms under salt stress is almost unknown. Therefore, an indoor incubation test was performed, and the denaturing gradient gel electrophoresis (DGGE) approach was used to determine the response of different saline soil bacterial and fungal community structures to the presence of imidacloprid (0.4, 2, 10 mg kg(-1)). The results showed that the soil bacterial diversity slightly declined with increasing imidacloprid concentration in soils with low salinity. In moderately saline soils, a new band in the DGGE profile suggested that imidacloprid could improve the soil bacterial diversity to some degree. An analysis of variance indicated that the measured soil bacterial diversity parameters were significantly affected by dose and incubation time. Compared with the control, the soil fungal community structure showed no obvious changes in low and moderately saline soils treated with imidacloprid. The results of these observations provide a basic understanding of the potential ecological effects of imidacloprid on different microorganisms in saline soils.

  3. Microbial Community Structure of Casing Soil During Mushroom Growth

    Institute of Scientific and Technical Information of China (English)

    CAI Wei-Ming; YAO Huai-Ying; FENG Wei-Lin; JIN Qun-Li; LIU Yue-Yan; LI Nan-Yi; ZHENG Zhong

    2009-01-01

    The culturable bacterial population and phospholipid fatty acid (PLFA)profile of casing soil were investigated at different mushroom (Agaricus bisporusI cropping stages.The change in soil bacterial PLFAs was always accompanied by a change in the soil culturable bacterial population in the first flush.Comparatively higher culturable bacterial population and bacterial PLFAs were found in the casing soil at the primordia formation stage of the first flush.There was a significant increase in the ratio of fungal to bacterial PLFAs during mushroom growth.Multivariate analysis of PLFA data demonstrated that the mushroom cropping stage could considerably affect the microbial community structure of the casing soil.The bacterial population increased significantly from casing soil application to the primordia formation stage of the first flush.Casing soil application resulted in an increase in the ratio of gram-negative bacterial PLFAs to gram-positive bacterial PLFAs,suggesting that some gram-negative bacteria might play an important role in mushroom sporophore initiation.

  4. [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.

  5. Effects of Bio-char on Soil Microbes in Herbicide Residual Soils

    Directory of Open Access Journals (Sweden)

    WANG Gen-lin

    2015-10-01

    Full Text Available Effects of biological carbon (bio-char on soil microbial community were studied by pot experiments simulating long residual herbicide residues in soil environment, which clarifed the improvement of biochar and its structural properties on soil microenvironment. The results showed that fungi and actinomycetes had the same effect tendency within 0~0.72 mg·kg-1 in clomazone residue which increased the role of stimulation with crop growth process prolonged, especially in high residue treatment, but strong inhibitory effect on bacteria community was occured early which returned to normal until sugar beet growth to fiftieth day. Soil fungi community decreased with bio-char adding, but had no significant difference with the control. When clomazone residue in soil was below 0.24 mg·kg-1, soil actinomycetes community was higher than control without bio-char, bacteria increased first and then reduced after adding carbon as below 0.12 mg·kg-1. Biochar was ‘deep hole’ structure containing C, O, S and other elements. The results showed that a certain concentration clomazone residue in soil would stimulate soil fungi and actinomycetes to grow. After adding the biochar, the inhibition effect of high herbicides residual on bacterial would be alleviated.

  6. Marble waste and pig manure amendments decrease metal availability, increase soil quality and facilitate vegetation development in bare mine soils

    Science.gov (United States)

    Zornoza, Raúl; Faz, Ángel; Martínez-Martínez, Silvia; Acosta, José A.; Gómez, M. Dolores; Ángeles Muñoz, M.

    2013-04-01

    In order to bring out a functional and sustainable land use in a highly contaminated mine tailing, firstly environmental risks have to be reduced or eliminated by suitable reclamation activities. Tailing ponds pose environmental hazards, such as acidity and toxic metals reaching to waters through wind and water erosions and leaching. As a consequence, soils have no vegetation and low soil organic matter and nutrients. Various physicochemical and biochemical properties, together with exchangeable metals were measured before, 6 months and 12 months after the application of marble waste and pigs manure as reclamation strategy in a tailing pond from SE Spain to reduce hazards for environment and human health. Three months after the last addition of amendments, eight different native shrub species where planted for phytostabilization. Results showed the pH increased up to neutrality. Aggregates stability, organic carbon, total nitrogen, cation exchange capacity, bioavailable phosphorus and potassium, microbial biomass and microbial activity increased with the application of the amendments, while exchangeable metals drastically decreased (~90%). After one year of plantation, only 20% planted species died, with a high growth of survivals reaching flowering and fructification. This study confirms the high effectiveness of initial applications of marble wastes together with pig manure and plantation of shrub species to initialize the recovery of the ecosystem in bare mine soils under Mediterranean semiarid conditions. Key Words: pig manure, marble waste, heavy metals, mine soil. Acknowledgements This work has been funded by the European Union LIFE+ project MIPOLARE (LIFE09 ENV/ES/000439). J.A. Acosta acknowledges a "Saavedra Fajardo" contract from Comunidad Autónoma de Murcia (Spain)

  7. Parental material and cultivation determine soil bacterial community structure and fertility.

    Science.gov (United States)

    Sun, Li; Gao, Jusheng; Huang, Ting; Kendall, Joshua R A; Shen, Qirong; Zhang, Ruifu

    2015-01-01

    Microbes are the key components of the soil environment, playing important roles during soil development. Soil parent material provides the foundation elements that comprise the basic nutritional environment for the development of microbial community. After 30 years artificial maturation of cultivation, the soil developments of three different parental materials were evaluated and bacterial community compositions were investigated using the high-throughput sequencing approach. Thirty years of cultivation increased the soil fertility and soil microbial biomass, richness and diversity, greatly changed the soil bacterial communities, the proportion of phylum Actinobacteria decreased significantly, while the relative abundances of the phyla Acidobacteria, Chloroflexi, Gemmatimonadetes, Armatimonadetes and Nitrospira were significantly increased. Soil bacterial communities of parental materials were separated with the cultivated ones, and comparisons of different soil types, granite soil and quaternary red clay soil were similar and different with purple sandy shale soil in both parental materials and cultivated treatments. Bacterial community variations in the three soil types were affected by different factors, and their alteration patterns in the soil development also varied with soil type. Soil properties (except total potassium) had a significant effect on the soil bacterial communities in all three soil types and a close relationship with abundant bacterial phyla. The amounts of nitrogen-fixing bacteria as well as the abundances of the nifH gene in all cultivated soils were higher than those in the parental materials; Burkholderia and Rhizobacte were enriched significantly with long-term cultivation. The results suggested that crop system would not deplete the nutrients of soil parental materials in early stage of soil maturation, instead it increased soil fertility and changed bacterial community, specially enriched the nitrogen-fixing bacteria to accumulate

  8. Irradiated sewage sludge for increased crop production - III. Macronutrient availability

    International Nuclear Information System (INIS)

    El-Motaium, R.; Badawy, S.H.

    2002-01-01

    Irradiated and non-irradiated sewage sludge, from El-Gabal El-Asfar Farm near Cairo, were applied to tomato (Lycopersicon esculentum cv. GS) grown in a calcareous and a sandy soil at rates of 20, 40, 60, and 80 t/ha. Unfertilized controls and basal-fertilizer treatments were included. Total concentrations of micronutrients (Cu, Zn, Fe, Mn) in sludge-treated calcareous soil were higher than those in the sandy soil, although DTPA-extractable micronutrient concentrations were lower. There were no significant differences between irradiated and non-irradiated sludge treatments in DTPA-extractable and total micronutrient concentrations for the calcareous or the sandy soil. The total micronutrient concentrations for the highest sludge application rate (80 t/ha) were 5,108, 125, 68.2, and 207 μg/g in the calcareous soil and 2,200, 74.8, 43.2, and 139 μg/g in the sandy soil for Fe, Mn, Cu, and Zn, respectively, whereas the DTPA-extractable micronutrient concentrations were 25.0, 6.2, 5.5 and 6.6 μg/g in the calcareous soil and 53.3, 10.1, 7.3 and 9.83 μg/g in the sandy soil, respectively. Highly significant differences were observed in total and available micronutrient concentrations in calcareous and sandy soils among the sludge-application rates. Micronutrient concentrations of tomato leaves and fruits increased with increasing application rates of irradiated and non-irradiated sludge, and were higher in the sandy than in the calcareous soil for the same treatment. Highly significant differences were observed among the sludge-application rates in terms of the concentrations of micronutrients in both leaves and fruits. However, there were no significant differences between the irradiated and non-irradiated sludge treatments in the micronutrient concentrations of leaves and fruits in either soil. Micronutrient uptake increased with increasing rates of application of sludge to the soil, more so in the sandy than in the calcareous soil. The amounts of Fe, Mn, Cu, and Zn

  9. Irradiated sewage sludge for increased crop production - III. Macronutrient availability

    International Nuclear Information System (INIS)

    El-Motaium, R.; Badawy, S.H.

    2002-01-01

    Irradiated and non-irradiated sewage sludge, from El-Gabal El-Asfar Farm near Cairo, were applied to tomato (Lycopersicon esculentum cv. GS) grown in a calcareous and a sandy soil at rates of 20, 40, 60, and 80 t/ha. Unfertilized controls and basal-fertilizer treatments were included. Total concentrations of micronutrients (Cu, Zn, Fe, Mn) in sludge-treated calcareous soil were higher than those in the sandy soil, although DTPAextractable micronutrient concentrations were lower. There were no significant differences between irradiated and non-irradiated sludge treatments in DTPA-extractable and total micronutrient concentrations for the calcareous or the sandy soil. The total micronutrient concentrations for the highest sludge application rate (80 t/ha) were 5,108, 125, 68.2, and 207 μg/g in the calcareous soil and 2,200, 74.8, 43.2, and 139 μg/g in the sandy soil for Fe, Mn, Cu, and Zn, respectively, whereas the DTPA-extractable micronutrient concentrations were 25.0, 6.2, 5.5 and 6.6 μg/g in the calcareous soil and 53.3, 10.1, 7.3 and 9.83 μg/g in the sandy soil, respectively. Highly significant differences were observed in total and available micronutrient concentrations in calcareous and sandy soils among the sludge-application rates. Micronutrient concentrations of tomato leaves and fruits increased with increasing application rates of irradiated and non-irradiated sludge, and were higher in the sandy than in the calcareous soil for the same treatment. Highly significant differences were observed among the sludge-application rates in terms of the concentrations of micronutrients in both leaves and fruits. However, there were no significant differences between the irradiated and non-irradiated sludge treatments in the micronutrient concentrations of leaves and fruits in either soil. Micronutrient uptake increased with increasing rates of application of sludge to the soil, more so in the sandy than in the calcareous soil. The amounts of Fe, Mn, Cu, and Zn

  10. The Effect of Soil Warming on Decomposition of Biochar, Wood, and Bulk Soil Organic Carbon in Contrasting Temperate and Tropical Soils

    Science.gov (United States)

    Torn, Margaret; Tas, Neslihan; Reichl, Ken; Castanha, Cristina; Fischer, Marc; Abiven, Samuel; Schmidt, Michael; Brodie, Eoin; Jansson, Janet

    2013-04-01

    Biochar and wood are known to decay at different rates in soil, but the longterm effect of char versus unaltered wood inputs on soil carbon dynamics may vary by soil ecosystem and by their sensitivity to warming. We conducted an incubation experiment to explore three questions: (1) How do decomposition rates of char and wood vary with soil type and depth? (2) How vulnerable to warming are these slowly decomposing inputs? And (3) Do char or wood additions increase loss of native soil organic carbon (priming)? Soils from a Mediterranean grassland (Hopland Experimental Research Station, California) and a moist tropical forest (Tabunoco Forest, Puerto Rico) were collected from two soil depths and incubated at ambient temperature (14°C, 20°C for Hopland and Tabonuco respectively) and ambient +6°C. We added 13C-labeled wood and char (made from the wood at 450oC) to the soils and quantified CO2 and 13CO2 fluxes with continuous online carbon isotope measurements using a Cavity Ringdown Spectrometer (Picarro, Inc) for one year. As expected, in all treatments the wood decomposed much (about 50 times) more quickly than did the char amendment. With few exceptions, amendments placed in the surface soil decomposed more quickly than those in deeper soil, and in forest soil faster than that placed in grassland soil, at the same temperature. The two substrates were not very temperature sensitive. Both had Q10 less than 2 and char decomposition in particular was relatively insensitive to warming. Finally, the addition of wood caused a significant increase of roughly 30% in decomposition losses of the native soil organic carbon in the grassland and slightly less in forest. Char had only a slight positive priming effect but had a significant effect on microbial community. These results show that conversion of wood inputs to char through wildfire or intentional management will alter not only the persistence of the carbon in soil but also its temperature response and effect on

  11. Anaerobic digestate from biogas production as a resource for improving soil fertility: effects on crop yield and soil properties

    Science.gov (United States)

    Pastorelli, Roberta; Lagomarsino, Alessandra; Vignozzi, Nadia; Valboa, Giuseppe; Papini, Rossella; Fabiani, Arturo; Simoncini, Stefania; Mocali, Stefano; Piccolo, Raimondo

    2013-04-01

    Soil fertility is fundamental in determining crops productivity in all farming systems. Production of biogas through anaerobic digestion of energy crops generates residues that can represent a valuable resource to sustain and improve soil fertility and to increase soil organic matter content. Residues from anaerobic digestion contain organic fractions and available nutrients, that can thus be returned to the cultivation soil as fertilizer and soil conditioner. However, some unknown aspects of digested residues utilization remain to explore: i) the nutrient supply and the real potential for mineral fertilization substitution, ii) the impact on the structure and functioning of soil microbial communities, iii) the direct and indirect effects on soil structure, organic matter and C mineralization. The aim of the present research was to gain a better understanding of these aspects, evaluating the effects of anaerobic digestate application on soil properties and maize yield. With the main focus of comparing mineral fertilization (250 Kg N ha-1) with digested residues addition (at the dose of 25 % and 50 % of mineral fertilizer), a triplicate sets of plots were designed in a field experiment on a silty-clay loam soil in the southern Po Valley (Italy). The amount of applied residues was calculated according to its N content in order to fertilizer each plots with the same amount of total nitrogen. Residues from digestion showed a N content of 0.4 % (60 % as N-NH4) and a C/N ratio of 3. Changes in soil quality after residues application were studied with a holistic approach, involving microbiological, physical and chemical aspects of soil fertility. In particular, we determined: the abundance and diversity of bacterial and fungal soil communities; the soil organic matter content, its distribution within soil aggregates and the C mineralization potential; cation exchange capacity; the main macro and micro nutrients; bulk density; aggregate stability. No significant

  12. [Removal of volatile organic compounds in soils by soil vapor extraction (SVE)].

    Science.gov (United States)

    Yin, Fu-xiang; Zhang, Sheng-tian; Zhao, Xin; Feng, Ke; Lin, Yu-suo

    2011-05-01

    An experiment study has been carried out to investigate effects of the diameter of soil columns, the size of soil particulate and different contaminants on efficiency of simulated soil vapor extraction (SVE). Experiments with benzene, toluene, ethylbenzene and n-propylbenzene contaminated soils showed that larger bottom area/soil height (S/H) of the columns led to higher efficiency on removal of contaminants. Experiments with contaminated soils of different particulate size showed that the efficiency of SVE decreased with increases in soil particulate size, from 10 mesh to between 20 mesh and 40 mesh and removal of contaminants in soils became more difficult. Experiments with contaminated soils under different ventilation rates suggested that soil vapor extraction at a ventilation rate of 0.10 L x min(-1) can roughly remove most contaminants from the soils. Decreasing of contaminants in soils entered tailing stages after 12 h, 18 h and 48 h for benzene, toluene and ethylbenzene, respectively. Removal rate of TVOCs (Total VOCs) reached a level as high as 99.52%. The results of the experiment have indicated that molecule structure and properties of the VOCs are also important factors which have effects on removal rates of the contaminants. Increases in carbon number on the benzene ring, decreases in vapor pressure and volatile capability resulted in higher difficulties in soil decontamination. n-propylbenzene has a lower vapor pressure than toluene and ethylbenzene which led to a significant retard effect on desorption and volatilization of benzene and ethylbenzene.

  13. Influence of amendments on soil arsenic fractionation and phytoavailability by Pteris vittata L.

    Science.gov (United States)

    Yan, Xiulan; Zhang, Min; Liao, Xiaoyong; Tu, Shuxin

    2012-06-01

    Increasing availability of soil arsenic is of significance for accelerating phytoremediation efficiency of As-polluted sites. The effects of seven amendments, i.e., citrate, oxalate, EDTA, sodium polyacrylate (SPA), phosphate rock (PR), single superphosphate (SSP), and compost on fractionation and phytoavailability of soil As were investigated in lab culture experiment. The results showed that the addition of PR, SPA, EDTA or compost to soils significantly increased the concentration of NaHCO(3)-extractable As over a 120 d incubation period compared with the control (amendment-free) soil. Then, the four amendments were selected to add to As-contaminated soil growing Pteris vittata. It was concluded that As accumulation by the fern increased significantly under the treatments of PR and SPA by 25% and 31%, respectively. For As fractionation in soil, SPA increased Fe-As significantly by 51% and PR increased Ca-As significantly by 18%, while both the two amendments reduced occluded-As by 16% and 19%, respectively. Adding PR and SPA in soil increased the activities of urease and neutral phosphatase resulting from the improvement the fertility and physical structure of the soil, which benefits plant growth and As absorption of P. vittata. The results of the research revealed that both PR and SPA were effective amendments for improving phytoremediation of As-contaminated sites by P. vittata. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. 'Cabernet Sauvignon' grape anthocyanin increased by soil conservation practices

    Science.gov (United States)

    Cover crops and no-till (mown) systems provide multiple benefits to vineyard soils such as improvements in soil organic matter and reductions in erosion and dust generation. Understanding the effects of such practices on grape attributes will contribute to the sustainability of the production system...

  15. Restoring Soil Quality to Mitigate Soil Degradation

    Directory of Open Access Journals (Sweden)

    Rattan Lal

    2015-05-01

    Full Text Available Feeding the world population, 7.3 billion in 2015 and projected to increase to 9.5 billion by 2050, necessitates an increase in agricultural production of ~70% between 2005 and 2050. Soil degradation, characterized by decline in quality and decrease in ecosystem goods and services, is a major constraint to achieving the required increase in agricultural production. Soil is a non-renewable resource on human time scales with its vulnerability to degradation depending on complex interactions between processes, factors and causes occurring at a range of spatial and temporal scales. Among the major soil degradation processes are accelerated erosion, depletion of the soil organic carbon (SOC pool and loss in biodiversity, loss of soil fertility and elemental imbalance, acidification and salinization. Soil degradation trends can be reversed by conversion to a restorative land use and adoption of recommended management practices. The strategy is to minimize soil erosion, create positive SOC and N budgets, enhance activity and species diversity of soil biota (micro, meso, and macro, and improve structural stability and pore geometry. Improving soil quality (i.e., increasing SOC pool, improving soil structure, enhancing soil fertility can reduce risks of soil degradation (physical, chemical, biological and ecological while improving the environment. Increasing the SOC pool to above the critical level (10 to 15 g/kg is essential to set-in-motion the restorative trends. Site-specific techniques of restoring soil quality include conservation agriculture, integrated nutrient management, continuous vegetative cover such as residue mulch and cover cropping, and controlled grazing at appropriate stocking rates. The strategy is to produce “more from less” by reducing losses and increasing soil, water, and nutrient use efficiency.

  16. The significance of denitrification of applied nitrogen in fallow and cropped rice soils under different flooding regimes. Pt. 1

    International Nuclear Information System (INIS)

    Fillery, I.R.P.; Vlek, P.L.G.

    1982-01-01

    The role of nitrification-denitrification in the loss of nitrogen from urea applied to puddled soils planted to rice and subjected to continuous and intermittent flooding was evaluated in three greenhouse pot studies. The loss of N via denitrification was estimated indirectly using the 15 N balance, after either first accounting for NH 3 volatilization or by analyzing the 15 N balance immediately before and after the soil was dried and reflooded. When urea was broadcast and incorporated the loss of 15 N from the soil-plant systems depended on the soil, being about 20% - 25% for the silt loams and only 10% - 12% for the clay. Ammonia volatilization accounted for an average 20% of the N applied in the silt loam. Denitrification losses could not account for more than 10% of the applied N in any of the continuously flooded soil-plant systems under study and were most likely less than 5%. Intermittent flooding of soil planted to rice did not increase the loss of N. Denitrification appeared to be an important loss mechanism in continuously flooded fallow soils, accounting for the loss of approximately 40% of the applied 15 N. Loss of 15 N was not appreciably enhanced in fallow soils undergoing intermittent flooding. Apparently, nitrate formed in oxidized zones in the soil was readily denitrified in the absence of plant roots. Extensive loss (66%) of 15 N-labeled nitrate was obtained when 100 mg/pot of nitrate-N was applied to the surface of nonflooded soil prior to reflooding. This result suggests that rice plants may not compete effectively with denitrifiers if large quantities of nitrate were to accumulate during intermittent dry periods. (orig.)

  17. Effect of long-term farming strategies on soil microbiota and soil health

    Science.gov (United States)

    Sommermann, Loreen; Babin, Doreen; Sandmann, Martin; Smalla, Kornelia; Schellenberg, Ingo; Grosch, Rita; Geistlinger, Joerg

    2017-04-01

    Increasing food and energy demands have resulted in considerable intensification of farming practices, which brought about severe consequences for agricultural soils, e.g. loss of fertility, erosion and enrichment of soil-borne plant diseases. In order to maintain soil quality and health for the future, the development of more extensive and sustainable farming strategies is urgently needed. The soil microbiome is regarded as a key player in soil ecosystem functions, particularly the natural ability of soils to suppress plant pathogens (suppressiveness). Recent studies showed that soil microbial communities are influenced by agricultural management. To further analyze the effects of farming strategies on soil suppressiveness and plant performance, agricultural soils from three long-term field trials in Thyrow, Bernburg (both in Germany) and Therwil (Switzerland) were sampled and subjected to molecular profiling of soil bacteria and fungi using marker genes and high-throughput amplicon sequencing. Significant effects on bacterial as well as fungal community composition, including plant pathogenic and beneficial taxa, were observed among variants of tillage and crop rotation. The least effect on both communities had fertilization, with no significance between variants. Subsequently, the same soils were subjected to growth chamber pot experiments with lettuce as a model (Lactuca sativa). After a growth period of six weeks significant differences in lettuce shoot and soil microbial biomass were observed among soil samples of the different long-term trials. Furthermore, the lettuce rhizosphere exhibited diverse bacterial community compositions as observed by DGGE (denaturing gradient gel electrophoresis). Using group-specific PCR-DGGE fingerprints, bacterial responders to fertilization, soil management and crop rotation were identified among different taxonomic groups. Currently, bacterial and fungal amplicon sequencing of rhizosphere and bulk soil from these pot

  18. A novel soil manganese mechanism drives plant species loss with increased nitrogen deposition in a temperate steppe.

    Science.gov (United States)

    Tian, Qiuying; Liu, Nana; Bai, Wenming; Li, Linghao; Chen, Jiquan; Reich, Peter B; Yu, Qiang; Guo, Dali; Smith, Melinda D; Knapp, Alan K; Cheng, Weixin; Lu, Peng; Gao, Yan; Yang, An; Wang, Tianzuo; Li, Xin; Wang, Zhengwen; Ma, Yibing; Han, Xingguo; Zhang, Wen-Hao

    2016-01-01

    Loss of plant diversity with increased anthropogenic nitrogen (N) deposition in grasslands has occurred globally. In most cases, competitive exclusion driven by preemption of light or space is invoked as a key mechanism. Here, we provide evidence from a 9-yr N-addition experiment for an alternative mechanism: differential sensitivity of forbs and grasses to increased soil manganese (Mn) levels. In Inner Mongolia steppes, increasing the N supply shifted plant community composition from grass-forb codominance (primarily Stipa krylovii and Artemisia frigida, respectively) to exclusive dominance by grass, with associated declines in overall species richness. Reduced abundance of forbs was linked to soil acidification that increased mobilization of soil Mn, with a 10-fold greater accumulation of Mn in forbs than in grasses. The enhanced accumulation of Mn in forbs was correlated with reduced photosynthetic rates and growth, and is consistent with the loss of forb species. Differential accumulation of Mn between forbs and grasses can be linked to fundamental differences between dicots and monocots in the biochemical pathways regulating metal transport. These findings provide a mechanistic explanation for N-induced species loss in temperate grasslands by linking metal mobilization in soil to differential metal acquisition and impacts on key functional groups in these ecosystems.

  19. Effect of elevated CO2 on degradation of azoxystrobin and soil microbial activity in rice soil.

    Science.gov (United States)

    Manna, Suman; Singh, Neera; Singh, V P

    2013-04-01

    An experiment was conducted in open-top chambers (OTC) to study the effect of elevated CO2 (580 ± 20 μmol mol(-1)) on azoxystrobin degradation and soil microbial activities. Results indicated that elevated CO2 did not have any significant effect on the persistence of azoxystrobin in rice-planted soil. The half-life values for the azoxystrobin in rice soils were 20.3 days in control (rice grown at ambient CO2 outdoors), 19.3 days in rice grown under ambient CO2 atmosphere in OTC, and 17.5 days in rice grown under elevated CO2 atmosphere in OTC. Azoxystrobin acid was recovered as the only metabolite of azoxystrobin, but it did not accumulate in the soil/water and was further metabolized. Elevated CO2 enhanced soil microbial biomass (MBC) and alkaline phosphatase activity of soil. Compared with rice grown at ambient CO2 (both outdoors and in OTC), the soil MBC at elevated CO2 increased by twofold. Elevated CO2 did not affect dehydrogenase, fluorescein diacetate, and acid phosphatase activity. Azoxystrobin application to soils, both ambient and elevated CO2, inhibited alkaline phosphates activity, while no effect was observed on other enzymes. Slight increase (1.8-2 °C) in temperature inside OTC did not affect microbial parameters, as similar activities were recorded in rice grown outdoors and in OTC at ambient CO2. Higher MBC in soil at elevated CO2 could be attributed to increased carbon availability in the rhizosphere via plant metabolism and root secretion; however, it did not significantly increase azoxystrobin degradation, suggesting that pesticide degradation was not the result of soil MBC alone. Study suggested that increased CO2 levels following global warming might not adversely affect azoxystrobin degradation. However, global warming is a continuous and cumulative process, therefore, long-term studies are necessary to get more realistic assessment of global warming on fate of pesticide.

  20. Soil disturbance as a driver of increased stream salinity in a semiarid watershed undergoing energy development

    Science.gov (United States)

    Bern, Carleton R.; Clark, Melanie L.; Schmidt, Travis S.; Holloway, JoAnn M.; Mcdougal, Robert

    2015-01-01

    Salinization is a global threat to the quality of streams and rivers, but it can have many causes. Oil and gas development were investigated as one of several potential causes of changes in the salinity of Muddy Creek, which drains 2470 km2 of mostly public land in Wyoming, U.S.A. Stream discharge and salinity vary with seasonal snowmelt and define a primary salinity-discharge relationship. Salinity, measured by specific conductance, increased substantially in 2009 and was 53-71% higher at low discharge and 33-34% higher at high discharge for the years 2009-2012 compared to 2005-2008. Short-term processes (e.g., flushing of efflorescent salts) cause within-year deviations from the primary relation but do not obscure the overall increase in salinity. Dissolved elements associated with increased salinity include calcium, magnesium, and sulfate, a composition that points to native soil salts derived from marine shales as a likely source. Potential causes of the salinity increase were evaluated for consistency by using measured patterns in stream chemistry, slope of the salinity-discharge relationship, and inter-annual timing of the salinity increase. Potential causes that were inconsistent with one or more of those criteria included effects from precipitation, evapotranspiration, reservoirs, grazing, irrigation return flow, groundwater discharge, discharge of energy co-produced waters, and stream habitat restoration. In contrast, surface disturbance of naturally salt-rich soil by oil and gas development activities, such as pipeline, road, and well pad construction, is a reasonable candidate for explaining the salinity increase. As development continues to expand in semiarid lands worldwide, the potential for soil disturbance to increase stream salinity should be considered, particularly where soils host substantial quantities of native salts.

  1. Influence of Disturbance on Soil Respiration in Biologically Crusted Soil during the Dry Season

    Directory of Open Access Journals (Sweden)

    Wei Feng

    2013-01-01

    Full Text Available Soil respiration (Rs is a major pathway for carbon cycling and is a complex process involving abiotic and biotic factors. Biological soil crusts (BSCs are a key biotic component of desert ecosystems worldwide. In desert ecosystems, soils are protected from surface disturbance by BSCs, but it is unknown whether Rs is affected by disturbance of this crust layer. We measured Rs in three types of disturbed and undisturbed crusted soils (algae, lichen, and moss, as well as bare land from April to August, 2010, in Mu Us desert, northwest China. Rs was similar among undisturbed soils but increased significantly in disturbed moss and algae crusted soils. The variation of Rs in undisturbed and disturbed soil was related to soil bulk density. Disturbance also led to changes in soil organic carbon and fine particles contents, including declines of 60–70% in surface soil C and N, relative to predisturbance values. Once BSCs were disturbed, Q10 increased. Our findings indicate that a loss of BSCs cover will lead to greater soil C loss through respiration. Given these results, understanding the disturbance sensitivity impact on Rs could be helpful to modify soil management practices which promote carbon sequestration.

  2. Effect of crop sequence and crop residues on soil C, soil N and yield of maize

    International Nuclear Information System (INIS)

    Shafi, M.; Bakht, J.; Attaullah; Khan, M.A.

    2010-01-01

    Improved management of nitrogen (N) in low N soils is critical for increased soil productivity and crop sustainability. The objective of the present study was to evaluate the effects of residues incorporation, residues retention on soil surface as mulch, fertilizer N and legumes in crop rotation on soil fertility and yield of maize (Zea may L.). Fertilizer N was applied to maize at the rate of 160 kg ha/sup -1/, and to wheat at the rate of 120 kg ha/sup -1/ or no fertilizer N application. Crop rotation with the sequence of maize after wheat (Triticum aestivum L.), maize after lentil (Lens culinaris Medic) or wheat after mash bean (Vigna mungo L.) arranged in a split plot design was followed. Post-harvest incorporation of crop residues and residues retention on soil surface as mulch had significantly (p=0.05) affected grain and stover yield during 2004 and 2005. Two years average data revealed that grain yield was increased by 3.31 and 6.72% due to mulch and residues incorporation. Similarly, stover yield was also enhanced by 5.39 and 10.27% due to the same treatment respectively. Mulch and residues incorporation also improved stover N uptake by 2.23 and 6.58%, respectively. Total soil N and organic matter was non significantly (p=0.05) increased by 5.63 and 2.38% due to mulch and 4.13, 7.75% because of crop residues incorporation in the soil. Maize grain and stover yield responded significantly (p=0.05) to the previous legume (lentil) crop when compared with the previous cereal crop (wheat). The treatment of lentil - maize(+N), on the average, increased grain yield of maize by 15.35%, stover yield by 16.84%, total soil N by 10.31% and organic matter by 10.17%. Similarly, fertilizer N applied to the previous wheat showed carry over effect on grain yield (6.82%) and stover yield (11.37%) of the following maize crop. The present study suggested that retention of residues on soil surface as mulch, incorporation of residues in soil and legume (lentil - maize) rotation

  3. Effects of simulated acid rain on soil and soil solution chemistry in a monsoon evergreen broad-leaved forest in southern China.

    Science.gov (United States)

    Qiu, Qingyan; Wu, Jianping; Liang, Guohua; Liu, Juxiu; Chu, Guowei; Zhou, Guoyi; Zhang, Deqiang

    2015-05-01

    Acid rain is an environmental problem of increasing concern in China. In this study, a laboratory leaching column experiment with acid forest soil was set up to investigate the responses of soil and soil solution chemistry to simulated acid rain (SAR). Five pH levels of SAR were set: 2.5, 3.0, 3.5, 4.0, and 4.5 (as a control, CK). The results showed that soil acidification would occur when the pH of SAR was ≤3.5. The concentrations of NO₃(-)and Ca(2+) in the soil increased significantly when the pH of SAR fell 3.5. The concentration of SO₄(2-) in the soil increased significantly when the pH of SAR was soil solution chemistry became increasingly apparent as the experiment proceeded (except for Na(+) and dissolved organic carbon (DOC)). The net exports of NO₃(-), SO₄(2-), Mg(2+), and Ca(2+) increased about 42-86% under pH 2.5 treatment as compared to CK. The Ca(2+) was sensitive to SAR, and the soil could release Ca(2+) through mineral weathering to mitigate soil acidification. The concentration of exchangeable Al(3+) in the soil increased with increasing the acidity of SAR. The releases of soluble Al and Fe were SAR pH dependent, and their net exports under pH 2.5 treatment were 19.6 and 5.5 times, respectively, higher than that under CK. The net export of DOC was reduced by 12-29% under SAR treatments as compared to CK. Our results indicate the chemical constituents in the soil are more sensitive to SAR than those in the soil solution, and the effects of SAR on soil solution chemistry depend not only on the intensity of SAR but also on the duration of SAR addition. The soil and soil solution chemistry in this region may not be affected by current precipitation (pH≈4.5) in short term, but the soil and soil leachate chemistry may change dramatically if the pH of precipitation were below 3.5 and 3.0, respectively.

  4. Integrated use of biochar: a tool for improving soil and wheat quality of degraded soil under wheat-maize cropping pattern

    International Nuclear Information System (INIS)

    Ali, K.; Arif, M.; Jan, M.T.

    2015-01-01

    Wheat quality, nutrient uptake and nutrient use efficiency are significantly influenced by nutrient sources and application rate. To investigate the integrative effect of biochar, farmyard manure (FYM) and nitrogen (organic and inorganic soil amendments) in a wheat-maize cropping system, a two year study was designed to assess the interactive outcome of biochar, FYM and nitrogenous fertilizer on wheat nitrogen (N) parameters and associated soil quality parameters. Three levels of biochar (0, 25 and 50 t ha-1), two levels of FYM (5 and 10 t ha-1) and two levels of nitrogen fertilizer (60 and 120 kg ha-1) were used in the study. Biochar application displayed a significantly increased in wheat leaf, stem, straw and grain N content; grain and total N-uptake and grain protein content by 24, 20, 24, 56, 50, 17 and 20% respectively. Similarly, biochar application significantly increased soil total N (TN) and soil mineral N (SMN) by 63 and 40% respectively in second year. FYM application increased grain, leaf and straw N content by 20, 19.5 and 18% respectively, and increased total N-uptake and grain protein content by 49 and 19% respectively. FYM increased soil TN and SMN by 63 and 32% in both the years of the experiment. Mineral N application increased soil TN by over a half and SMN by a third, and grain protein content increased 16%. In contrast, nitrogen use efficiency (NUE) decreased for all amendments relative to the control. However, biochar treated plots improved NUE by 38% compared to plots without biochar. In conclusion, this field experiment has illustrated the potential of biochar to bring about short-term benefits in wheat and soil quality parameters in wheat-maize cropping systems. However, the long-term benefits remain to be quantified. (author)

  5. Exponential increase of publications related to soil water repellency

    NARCIS (Netherlands)

    Dekker, L.W.; Oostindie, K.; Ritsema, C.J.

    2005-01-01

    Soil water repellency is much more wide-spread than formerly thought. During the last decades, it has been a topic of study for soil scientists and hydrologists in at least 21 States of the USA, in Canada, Australia, New Zealand, Mexico, Colombia, Chile, Congo, Nepal, India, Hong Kong, Taiwan,

  6. Calcium soil amendment increases resistance of potato to blackleg ...

    African Journals Online (AJOL)

    This study shows that calcium soil amendments reduce blackleg and soft rot diseases under Zimbabwe's growing seasons in red fersiallitic soils. Compound S produces better results in potato production than compound D and farmers should be encouraged to use compound S when growing potatoes. Key words: potato ...

  7. [Relationships between vegetation characteristics and soil properties at different restoration stages on slope land with purple soils in Hengyang of Hunan Province, South-central China].

    Science.gov (United States)

    Yang, Ning; Zou, Dong-Sheng; Yang, Man-Yuan; Hu, Li-Zhen; Zou, Fang-Ping; Song, Guang-Tao; Lin, Zhong-Gui

    2013-01-01

    By using space series to replace time series, this paper studied the relationships between the vegetation characteristics and soil properties at different restoration stages on the slope land with purple soils in Hengyang of Hunnan Province South-central China. There existed obvious differences in the soil physical and chemical properties at different restoration stages. From grassplot, grass-shrub, shrub to shrub-arbor, the soil organic matter, total and available N, and moisture contents increased markedly, soil bulk density had an obvious decrease, soil total and available P contents changed little, and soil pH decreased gradually, but no significant differences were observed among different restoration stages. At different restoration stages, the biomass of plant community had effects on the quantity and composition of soil microbes. The quantities of soil bacteria and fungi had significant positive correlations with the aboveground biomass of plant community, but the quantity of soil actinomycetes had less correlation with plant community's aboveground biomass. At different restoration stages, the activities of soil urease, protease, alkaline phosphatase, invertase, cellulase, catalase, and polyphenol oxidase decreased with increasing soil layer, and had significant positive correlations with plant community's richness and aboveground biomass.

  8. Utilization of organic fertilizer to increase paddy growth and productivity using System of Rice Intensification (SRI method in saline soil

    Directory of Open Access Journals (Sweden)

    V . O . Subardja

    2016-01-01

    Full Text Available Soil salinity has negative effect on soil biodiversity as well as microbial activities. Hence, rice growth also effected by salinity. Application of organic fertilizer and adoption of System of Rice Intensification (SRI cultivation might improve the (biological soil properties and increase rice yield. The aim of this study was to evaluate the effect of two different rice cultivation methods namely conventional rice cultivation method and System of Rice Intensification (SRI rice cultivation method and two kinds organic fertilizer on improvement of soil biological properties and rice yield. In this study, a split plot experimental design was applied where rice cultivation method (conventional and SRI was the main plot and two kinds of organic fertilizer (market waste and rice straw was the sub plot. The treatments had four replicates. The results showed that SRI cultivation with market waste organic fertilizer could increase soil biological properties (population of microbe, fungi and soil respiration. The same treatment also increased rice growth and production. Combination of SRI and market waste organic fertilizer yielded the highest rice production (7.21 t/ha.

  9. [Immobilization remediation of Cd and Pb contaminated soil: remediation potential and soil environmental quality].

    Science.gov (United States)

    Sun, Yue-Bing; Wang, Peng-Chao; Xu, Ying-Ming; Sun, Yang; Qin, Xu; Zhao, Li-Jie; Wang, Lin; Liang, Xue-Feng

    2014-12-01

    A pot experiment was conducted to investigate the immobilization remediation effects of sepiolite on soils artificially combined contamination by Cd and Pb using a set of various pH and speciation of Cd and Pb in soil, heavy metal concentration in Oryza sativa L., and soil enzyme activity and microbial quantity. Results showed that the addition of sepiolite increased the soil pH, and the exchangeable fraction of heavy metals was converted into Fe-Mn oxide, organic and residual forms, the concentration of exchangeable form of Cd and Pb reduced by 1.4% - 72.9% and 11.8% - 51.4%, respectively, when compared with the control. The contents of heavy metals decreased with increasing sepiolite, with the maximal Cd reduction of 39.8%, 36.4%, 55.2% and 32.4%, respectively, and 22.1%, 54.6%, 43.5% and 17.8% for Pb, respectively, in the stems, leaves, brown rice and husk in contrast to CK. The addition of sepiolite could improve the soil environmental quality, the catalase and urease activities and the amount of bacteria and actinomycete were increased to some extents. Although the fungi number and invertase activity were inhibited compared with the control group, it was not significantly different (P > 0.05). The significant correlation between pH, available heavy metal content, urease and invertase activities and heavy metal concentration in the plants indicated that these parameters could be used to evaluate the effectiveness of stabilization remediation of heavy metal contaminated soil.

  10. Improving soil enzyme activities and related quality properties of reclaimed soil by applying weathered coal in opencast-mining areas of the Chinese loess plateau

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hua [College of Environment and Resources, Shanxi University, Taiyuan (China); CAS/Shandong Provincial Key Laboratory of Coastal Environmental Process, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences (CAS), Yantai (China); Shao, Hongbo [CAS/Shandong Provincial Key Laboratory of Coastal Environmental Process, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences (CAS), Yantai (China); Institute for Life Sciences, Qingdao University of Science and Technology (QUST), Qingdao (China); Li, Weixiang; Bi, Rutian [Shanxi Agricultural University, Taigu (China); Bai, Zhongke [Department of Land Science Technology, University of Geosciences, Beijing (China)

    2012-03-15

    There are many problems for the reclaimed soil in opencast-mining areas of the Loess Plateau of China such as poor soil structure and extreme poverty in soil nutrients and so on. For the sake of finding a better way to improve soil quality, the current study was to apply the weathered coal for repairing soil media and investigate the physicochemical properties of the reclaimed soil and the changes in enzyme activities after planting Robinia pseucdoacacia. The results showed that the application of the weathered coal significantly improved the quality of soil aggregates, increased the content of water stable aggregates, and the organic matter, humus, and the cation exchange capacity of topsoil were significantly improved, but it did not have a significant effect on soil pH. Planting R. pseucdoacacia significantly enhanced the activities of soil catalase, urease, and invertase, but the application of the weathered coal inhibited the activity of catalase. Although the application of appropriate weathered coal was able to significantly increase urease activity, the activities of catalase, urease, or invertase had a close link with the soil profile levels and time. This study suggests that applying weathered coals could improve the physicochemical properties and soil enzyme activities of the reclaimed soil in opencast-mining areas of the Loess Plateau of China and the optimum applied amount of the weathered coal for reclaimed soil remediation is about 27 000 kg hm{sup -2}. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Impact of sole cropping and multiple cropping on soil humified carbon fractions

    International Nuclear Information System (INIS)

    Radhakrishnan, R.; Lee, I.J.

    2014-01-01

    The present study was planned to improve our understanding how crop rotation can enhance humified C fractions. A long term experiment was conducted on Vanmeter farm of the Ohio State University South Centers at Piketon Ohio, USA from 2002 to 2007. Crop rotation treatments included were continuous corn (CC), corn-soybean (CS) and corn-soybean-wheat-cowpea (CSW) rotations. Randomized complete block design with 6 replications was used under natural field conditions. The findings of this long-term study revealed that multiple cropping had significantly improved humified carbon fractions compared to mono-cropping system. Although total humified carbon (THOC), sugar free humified carbon (HOC) concentration were non-significant however, humin (NH) contents, humic (HA), fulvic acids (FA), humic and fulvic acid associated glucose (HA-NH and FA-NH) were significantly affected by various crop rotations within five years. The soil under CC had 22-52% significantly greater NH concentration than CSW and CS rotations respectively. Similarly all crop rotations had shown 5-16 increase in HA and 5-17% decreased in FA over time. Likewise soil under CC had 16 and 54% greater HA-NH concentration as compared to CSW and CS rotations. The FA-NH concentration increased significantly by 27- 51% in soil under all treatments over time. The soil under CSW had greater HA/FA (1.6) fallowed by CC (1.4) and CS (1.1). Soils under CSW had significantly greater HA/HOC (12-18%) as compare to CC and CS respectively. Conversely, the value of FA/HOC decreased (1-23%) in soil under all crop rotation treatments within five years. Degree of humification (DH) had shown a significant increase (7-12%) in soil under all treatments as compared to 2002. Irrespective of crop rotation THOC, HOC, NH, humin, HA, HR and FA/HOC concentration decreased significantly with increase in soil depth. While fulvic acid concentration HA/HOC in all crop rotation increased with increase in soil depth. The effect of crop rotation

  12. Irrigation and Nitrogen Regimes Promote the Use of Soil Water and Nitrate Nitrogen from Deep Soil Layers by Regulating Root Growth in Wheat.

    Science.gov (United States)

    Liu, Weixing; Ma, Geng; Wang, Chenyang; Wang, Jiarui; Lu, Hongfang; Li, Shasha; Feng, Wei; Xie, Yingxin; Ma, Dongyun; Kang, Guozhang

    2018-01-01

    Unreasonably high irrigation levels and excessive nitrogen (N) supplementation are common occurrences in the North China Plain that affect winter wheat production. Therefore, a 6-yr-long stationary field experiment was conducted to investigate the effects of irrigation and N regimes on root development and their relationship with soil water and N use in different soil layers. Compared to the non-irrigated treatment (W0), a single irrigation at jointing (W1) significantly increased yield by 3.6-45.6%. With increases in water (W2, a second irrigation at flowering), grain yield was significantly improved by 14.1-45.3% compared to the W1 treatments during the drier growing seasons (2010-2011, 2012-2013, and 2015-2016). However, under sufficient pre-sowing soil moisture conditions, grain yield was not increased, and water use efficiency (WUE) decreased significantly in the W2 treatments during normal precipitation seasons (2011-2012, 2013-2014, and 2014-2015). Irrigating the soil twice inhibited root growth into the deeper soil depth profiles and thus weakened the utilization of soil water and NO 3 -N from the deep soil layers. N applications increased yield by 19.1-64.5%, with a corresponding increase in WUE of 66.9-83.9% compared to the no-N treatment (N0). However, there was no further increase in grain yield and the WUE response when N rates exceeded 240 and 180 kg N ha -1 , respectively. A N application rate of 240 kg ha -1 facilitated root growth in the deep soil layers, which was conducive to utilization of soil water and NO 3 -N and also in reducing the residual NO 3 -N. Correlation analysis indicated that the grain yield was significantly positively correlated with soil water storage (SWS) and nitrate nitrogen accumulation (SNA) prior to sowing. Therefore, N rates of 180-240 kg ha -1 with two irrigations can reduce the risk of yield loss that occurs due to reduced precipitation during the wheat growing seasons, while under better soil moisture conditions, a

  13. Spatial changes in soil organic carbon density and storage of cultivated soils in China from 1980 to 2000

    Science.gov (United States)

    Yu, Yanyan; Guo, Zhengtang; Wu, Haibin; Kahmann, Julia A.; Oldfield, Frank

    2009-06-01

    We address the spatial changes in organic carbon density and storage in cultivated soils in China from 1980 to 2000 on the basis of measured data from individual studies and those acquired during the second national soil survey in China. The results show a carbon gain in ˜66% of the cultivated area of China as a whole with the increase in soil organic carbon (SOC) density mostly ranging from 10% to 30%. Soil organic carbon density increased in fluvi-aquic soils (fluvisols, Food and Agriculture Organization (FAO) of the United Nations) in north China, irrigated silting soils (calcaric fluvisols) in northwest China, latosolic red earths (haplic acrisols/alisols), and paddy soils (fluvisols/cambisols) in south China. In contrast, significant decreases are observed in black soils (phaeozems) in northeast China and latosols (haplic acrisols) in southwest China. No significant changes are detected in loessial soils (calcaric regosols) and dark loessial soils (calcisols) in the loess plateau region. The total SOC storage and average density in the upper 20 cm in the late 1990s are estimated to be ˜5.37 Pg C and 2.77 kg/m2, respectively, compared with the values of ˜5.11 Pg C and 2.63 kg/m2 in the early 1980s. This reveals an increase of SOC storage of 0.26 Pg C and suggests an overall carbon sink for cultivated soils in China, which has contributed 2-3% to the global terrestrial ecosystem carbon absorption from 1980 to 2000. Statistical analyses suggest an insignificant contribution to the observed SOC increase from climate change, and we infer that it is mostly attributable to improved agricultural practices. Despite the SOC density increases over 20 years, the SOC density of the cultivated soils in China in the late 1990s is still ˜30% lower compared to their uncultivated counterparts in comparable soil types, suggesting a considerable potential for SOC restoration through improving management practices. Assuming a restoration of ˜50% of the lost SOC in the next 30

  14. Effects of Modifiers on Physiological Metabolism of Lolium perenne Seedlings in Diesel-Polluted Soils

    Directory of Open Access Journals (Sweden)

    ZHAO Xuan

    2017-06-01

    Full Text Available The pot experiment for single-factor with diesel oil polluted soil and the pot experiment for three-factor orthogonal with sawdust-ammonium nitrate-monopotassium phosphate under diesel oil polluted soil with salt stress, were performed to analyze the activity of antioxidant enzymes and chlorophyll content in Lolium perenne seedlings, and to explore the physiological response of L. perenne seedlings under diesel oil polluted soil and its regulations. The results showed that, soil diesel pollution significantly decreased the biomass. Compared with control, activity of superoxide dismutases(SOD in leaf decreased significantly at 0.3% and 0.9% soil diesel pollution, peroxidases (POD and catalase(CAT in leaf decreased significantly at 0.6% and 0.9% soil diesel pollution, the root SOD activity increased significantly at 0.9% diesel concentration while the root POD activity decreased significantly at 0.6% and 0.9% soil diesel pollution. As for the salinity soil polluted by diesel oil, the activity of POD and CAT in leaf increased significantly at 10% volume fraction of sawdust, and the content of chlorophyll a and chlorophyll b increased significantly as well. Meanwhile, chlorophyll a and chlorophyll b content increased significantly at 0.3 g·kg-1 amount of ammonium nitrate. Thereby, sawdust and ammonium nitrate addition could effectively improve physiological metabolic of L. perenne seedlings.

  15. Intrinsic and induced isoproturon catabolic activity in dissimilar soils and soils under dissimilar land use.

    Science.gov (United States)

    Reid, Brian J; Papanikolaou, Niki D; Wilcox, Ronah K

    2005-02-01

    The catabolic activity with respect to the systemic herbicide isoproturon was determined in soil samples by (14)C-radiorespirometry. The first experiment assessed levels of intrinsic catabolic activity in soil samples that represented three dissimilar soil series under arable cultivation. Results showed average extents of isoproturon mineralisation (after 240 h assay time) in the three soil series to be low. A second experiment assessed the impact of addition of isoproturon (0.05 microg kg(-1)) into these soils on the levels of catabolic activity following 28 days of incubation. Increased catabolic activity was observed in all three soils. A third experiment assessed levels of intrinsic catabolic activity in soil samples representing a single soil series managed under either conventional agricultural practice (including the use of isoproturon) or organic farming practice (with no use of isoproturon). Results showed higher (and more consistent) levels of isoproturon mineralisation in the soil samples collected from conventional land use. The final experiment assessed the impact of isoproturon addition on the levels of inducible catabolic activity in these soils. The results showed no significant difference in the case of the conventional farm soil samples while the induction of catabolic activity in the organic farm soil samples was significant.

  16. 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...

  17. Analysis on soil compressibility changes of samples stabilized with lime

    Directory of Open Access Journals (Sweden)

    Elena-Andreea CALARASU

    2016-12-01

    Full Text Available In order to manage and control the stability of buildings located on difficult foundation soils, several techniques of soil stabilization were developed and applied worldwide. Taking into account the major significance of soil compressibility on construction durability and safety, the soil stabilization with a binder like lime is considered one of the most used and traditional methods. The present paper aims to assess the effect of lime content on soil geotechnical parameters, especially on compressibility ones, based on laboratory experimental tests, for several soil categories in admixture with different lime dosages. The results of this study indicate a significant improvement of stabilized soil parameters, such as compressibility and plasticity, in comparison with natural samples. The effect of lime stabilization is related to an increase of soil structure stability by increasing the bearing capacity.

  18. Influence of temperature and organic matter content on soil respiration in a deciduous oak forest

    Directory of Open Access Journals (Sweden)

    Zsolt Kotroczó

    2014-12-01

    Full Text Available The increasing temperature enhances soil respiration differently depend on different conditions (soil moisture, soil organic matter, the activity of soil microbes. It is an essential factor to predicting the effect of climate change on soil respiration. In a temperate deciduous forest (North-Hungary we added or removal aboveground and belowground litter to determine total soil respiration. We investigated the relationship between total soil CO2 efflux, soil moisture and soil temperature. Soil CO2 efflux was measured at each plot using chamber based soil respiration measurements. We determined the temperature sensitivity of soil respiration. The effect of doubled litter was less than the effect of removal. We found that temperature was more influential in the control of soil respiration than soil moisture in litter removal treatments, particularly in the wetter root exclusion treatments (NR and NI (R2: 0.49-0.61. Soil moisture (R2: 0.18-0.24 and temperature (R2: 0.18-0.20 influenced soil respiration similarly in treatments, where soil was drier (Control, Double Litter, Double Wood. A significantly greater increase in temperature induced higher soil respiration were significantly higher (2-2.5-fold in root exclusion treatments, where soil was wetter throughout the year, than in control and litter addition treatments. The highest bacterial and fungal count was at the DL treatment but the differences is not significant compared to the Control. The bacterial number at the No Litter, No Root, No Input treatment was significantly lower at the Control. Similar phenomenon can be observed at the fungal too, but the differences are not significant. The results of soil respiration suggest that the soil aridity can reduce soil respiration increases with the temperature increase. Soil bacterial and fungal count results show the higher organic matter content and soil surface cover litter favors the activity.

  19. Optimization of surfactant-aided remediation of industrially contaminated soils

    International Nuclear Information System (INIS)

    Joshi, M.M.; Lee, S.

    1996-01-01

    Soil matrices contaminated with polycyclic aromatic hydrocarbons (PAHs) abound at the sites of coke-oven gas plants, refineries, and many other major chemical industries. The removal of PAHs from soil using pure water, via soil washing (ex situ) or soil flushing (in situ), is quite ineffective due to their low solubility and hydrophobicity. However, addition of suitable surfactant(s) has been shown to increase the removal efficiency several fold. For the present work, the removal of PAHs occurring in industrially contaminated soil was studied. The objective was to use a nonionic surfactant solution for in situ soil flushing and to evaluate the optimal range of process parameters that can significantly increase the removal efficiency. The process parameters chosen were surfactant concentration, ratio of washing solution volume to soil weight, and temperature of washing solution. These parameters were found to have a significant effect on PAH removal from the contaminated soil and an optimal range was determined for each parameter under given washing conditions

  20. Extreme soil acidity from biodegradable trap and skeet targets increases severity of pollution at shooting ranges.

    Science.gov (United States)

    McTee, Michael R; Mummey, Daniel L; Ramsey, Philip W; Hinman, Nancy W

    2016-01-01

    Lead pollution at shooting ranges overshadows the potential for contamination issues from trap and skeet targets. We studied the environmental influence of targets sold as biodegradable by determining the components of the targets and sampling soils at a former sporting clay range. Targets comprised approximately 53% CaCO3, 41% S(0), and 6% modifiers, and on a molar basis, there was 2.3 times more S(0) than CaCO3. We observed a positive correlation between target cover and SO4(2-) (ρ=0.82, Psoil pH (ρ=0.62, P=0.006). For sites that had pH values below 3, 24tons of lime per 1000tons of soil would be required to raise soil pH to 6.5. Lime-facilitated pH increases would be transitory because S(0) would continue to oxidize to H2SO4 until the S(0) is depleted. This study demonstrates that biodegradable trap and skeet targets can acidify soil, which has implications for increasing the mobility of Pb from shotgun pellets. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Soil Nematode Response to Biochar Addition in a Chinese Wheat Field

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-Ke; LI Qi; LIANG Wen-Ju; ZHANG Min; BAO Xue-Lian; XIE Zu-Bin

    2013-01-01

    While studies have focused on the use of biochar as soil amendment,little attention has been paid to its effect on soil fauna.The biochar was produced from slow pyrolysis of wheat straw in the present study.Four treatments,no addition (CK) and three rates of biochar addition at 2400 (B1),12000 (B5) and 48000 kg ha-1 (B20),were investigated to assess the effect of biochar addition to soil on nematode abundance and diversity in a microcosm trial in China.The B5 and B20 application significantly increased the total organic carbon and the C/N ratio.No significant difference in total nematode abundance was found among the treatments.The biochar addition to the soil significantly increased the abundance of fungivores,and decreased that of plant parasites.The diversity of soil nematodes was significantly increased by B1 compared to CK.Nematode trophic groups were more effectively indicative to biochar addition than total abundance.

  2. Responses of soil respiration to soil management changes in an agropastoral ecotone in Inner Mongolia, China.

    Science.gov (United States)

    Xue, Haili; Tang, Haiping

    2018-01-01

    Studying the responses of soil respiration ( R s ) to soil management changes is critical for enhancing our understanding of the global carbon cycle and has practical implications for grassland management. Therefore, the objectives of this study were (1) quantify daily and seasonal patterns of R s , (2) evaluate the influence of abiotic factors on R s , and (3) detect the effects of soil management changes on R s . We hypothesized that (1) most of daily and seasonal variation in R s could be explained by soil temperature ( T s ) and soil water content ( S w ), (2) soil management changes could significantly affect R s , and (3) soil management changes affected R s via the significant change in abiotic and biotic factors. In situ R s values were monitored in an agropastoral ecotone in Inner Mongolia, China, during the growing seasons in 2009 (August to October) and 2010 (May to October). The soil management changes sequences included free grazing grassland (FG), cropland (CL), grazing enclosure grassland (GE), and abandoned cultivated grassland (AC). During the growing season in 2010, cumulative R s for FG, CL, GE, and AC averaged 265.97, 344.74, 236.70, and 226.42 gC m -2  year -1 , respectively. The T s and S w significantly influenced R s and explained 66%-86% of the variability in daily R s . Monthly mean temperature and precipitation explained 78%-96% of the variability in monthly R s . The results clearly showed that R s was increased by 29% with the conversion of FG to CL and decreased by 35% and 11% with the conversion of CL to AC and FG to GE. The factors impacting the change in R s under different soil management changes sequences varied. Our results confirm the tested hypotheses. The increase in Q 1 0 and litter biomass induced by conversion of FG to GE could lead to increased R s if the climate warming. We suggest that after proper natural restoration period, grasslands should be utilized properly to decrease R s .

  3. Intrinsic and induced isoproturon catabolic activity in dissimilar soils and soils under dissimilar land use

    International Nuclear Information System (INIS)

    Reid, Brian J.; Papanikolaou, Niki D.; Wilcox, Ronah K.

    2005-01-01

    The catabolic activity with respect to the systemic herbicide isoproturon was determined in soil samples by 14 C-radiorespirometry. The first experiment assessed levels of intrinsic catabolic activity in soil samples that represented three dissimilar soil series under arable cultivation. Results showed average extents of isoproturon mineralisation (after 240 h assay time) in the three soil series to be low. A second experiment assessed the impact of addition of isoproturon (0.05 μg kg -1 ) into these soils on the levels of catabolic activity following 28 days of incubation. Increased catabolic activity was observed in all three soils. A third experiment assessed levels of intrinsic catabolic activity in soil samples representing a single soil series managed under either conventional agricultural practice (including the use of isoproturon) or organic farming practice (with no use of isoproturon). Results showed higher (and more consistent) levels of isoproturon mineralisation in the soil samples collected from conventional land use. The final experiment assessed the impact of isoproturon addition on the levels of inducible catabolic activity in these soils. The results showed no significant difference in the case of the conventional farm soil samples while the induction of catabolic activity in the organic farm soil samples was significant. - Dissimilar levels of isoproturon catabolic activity in dissimilar soils and soils under dissimilar land use influence inferred risk

  4. Intrinsic and induced isoproturon catabolic activity in dissimilar soils and soils under dissimilar land use

    Energy Technology Data Exchange (ETDEWEB)

    Reid, Brian J. [School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ (United Kingdom)]. E-mail: b.reid@uea.ac.uk; Papanikolaou, Niki D. [School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ (United Kingdom); Wilcox, Ronah K. [School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ (United Kingdom)

    2005-02-01

    The catabolic activity with respect to the systemic herbicide isoproturon was determined in soil samples by {sup 14}C-radiorespirometry. The first experiment assessed levels of intrinsic catabolic activity in soil samples that represented three dissimilar soil series under arable cultivation. Results showed average extents of isoproturon mineralisation (after 240 h assay time) in the three soil series to be low. A second experiment assessed the impact of addition of isoproturon (0.05 {mu}g kg{sup -1}) into these soils on the levels of catabolic activity following 28 days of incubation. Increased catabolic activity was observed in all three soils. A third experiment assessed levels of intrinsic catabolic activity in soil samples representing a single soil series managed under either conventional agricultural practice (including the use of isoproturon) or organic farming practice (with no use of isoproturon). Results showed higher (and more consistent) levels of isoproturon mineralisation in the soil samples collected from conventional land use. The final experiment assessed the impact of isoproturon addition on the levels of inducible catabolic activity in these soils. The results showed no significant difference in the case of the conventional farm soil samples while the induction of catabolic activity in the organic farm soil samples was significant. - Dissimilar levels of isoproturon catabolic activity in dissimilar soils and soils under dissimilar land use influence inferred risk.

  5. [Research methods of carbon sequestration by soil aggregates: a review].

    Science.gov (United States)

    Chen, Xiao-Xia; Liang, Ai-Zhen; Zhang, Xiao-Ping

    2012-07-01

    To increase soil organic carbon content is critical for maintaining soil fertility and agricultural sustainable development and for mitigating increased greenhouse gases and the effects of global climate change. Soil aggregates are the main components of soil, and have significant effects on soil physical and chemical properties. The physical protection of soil organic carbon by soil aggregates is the important mechanism of soil carbon sequestration. This paper reviewed the organic carbon sequestration by soil aggregates, and introduced the classic and current methods in studying the mechanisms of carbon sequestration by soil aggregates. The main problems and further research trends in this study field were also discussed.

  6. [Soil basal respiration and enzyme activities in the root-layer soil of tea bushes in a red soil].

    Science.gov (United States)

    Yu, Shen; He, Zhenli; Zhang, Rongguang; Chen, Guochao; Huang, Changyong

    2003-02-01

    Soil basal respiration potential, metabolic quotient (qCO2), and activities of urease, invertase and acid phosphomonoesterase were investigated in the root-layer of 10-, 40-, and 90-yr-old tea bushes grown on the same type of red soil. The soil daily basal respiration potential ranged from 36.23 to 58.52 mg.kg-1.d-1, and the potentials in the root-layer of 40- or 90-yr-old were greater than that of 10-yr old tea bushes. The daily qCO2, ranging from 0.30 to 0.68, was in the reverse trend. The activities of test three enzymes changed differently with tea bushes' age. Urease activity in the root-layer of all age tea bushes ranged from 41.48 to 47.72 mg.kg-1.h-1 and slightly decreased with tea bushes' age. Invertase activity was 189.29-363.40 mg.kg-1.h-1 and decreased with tea bushes' age, but its activity in the root-layer of 10-year old tea bushes was significantly greater than that in the root-layer soil of 40- or 90-year old tea bushes. Acid phosphomonoesterase activity (444.22-828.32 mg.kg-1.h-1) increased significantly with tea bushes' age. Soil basal respiration potential, qCO2 and activities of 3 soil enzymes were closely related to soil pH, soil organic carbon, total nitrogen and C/N ratio, total soluble phenol, and microbial biomass carbon, respectively.

  7. Greater soil carbon accumulation in deeper soils in native- than in exotic-dominated grassland plantings in the southern Plains

    Science.gov (United States)

    Wilsey, B. J.; Xu, X.; Polley, H. W.; Hofmockel, K. S.

    2017-12-01

    Global change includes invasion by non-native plant species, and invasion may affect carbon cycling and storage. We tested predictions in central Texas in an experiment that compares mixtures of all exotic or all native species under two summer irrigation treatments (128 or 0 mm) that varies the amount of summer drought stress. At the end of the eighth growing season after establishment, soils were sampled in 10 cm increments to 100 cm depth to determine if soil C differed among treatments, and if treatments differentially affected soil C in deeper soils. Soil C content was significantly (5%) higher under native plantings than under exotic species plantings (P plantings increased with depth, and native plantings had higher soil C in deeper soil layers than in surface layers (native-exotic x depth, P plantings had decreasing soil C with depth. Soil C:N ratio and δ13C/12C were also significantly affected by native-exotic status, with soils in exotic plots having a significantly greater C4 contribution than native soils. Soil C was unaffected by summer irrigation treatments. Our results suggest that a significant amount of carbon could be sequestered by replacing exotic plant species with native species in the southern Plains, and that more work should be conducted at deeper soil depths. If we had restricted our analyses to surface soil layers (e.g. top 30 cm), we would have failed to detect depth differences between natives and exotics.

  8. The potential of agricultural practices to increase C storage in cropped soils: an assessment for France

    Science.gov (United States)

    Chenu, Claire; Angers, Denis; Métay, Aurélie; Colnenne, Caroline; Klumpp, Katja; Bamière, Laure; Pardon, Lenaic; Pellerin, Sylvain

    2014-05-01

    Though large progress has been achieved in the last decades, net GHG emissions from the agricultural sector are still more poorly quantified than in other sectors. In this study, we examined i) technical mitigation options likely to store carbon in agricultural soils, ii) their potential of additional C storage per unit surface area and iii) applicable areas in mainland France. We considered only agricultural practices being technically feasible by farmers and involving no major change in either production systems or production levels. Moreover, only currently available techniques with validated efficiencies and presenting no major negative environmental impacts were taken into account. Four measures were expected to store additional C in agricultural soils: - Reducing tillage: either a switch to continuous direct seeding, direct seeding with occasional tillage once every five years, or continuous superficial (20yrs) C storage rates (MgC ha-1 y-1,) of cropping systems with and without the proposed practice. Then we analysed the conditions for potential application, in terms of feasibility, acceptance, limitation of yield losses and of other GHG emissions. According to the literature, additional C storage rates were 0.15 (0-0.3) MgC ha-1 y-1 for continuous direct seeding, 0.10 (0-0.2) MgC ha-1 y-1for occasional tillage one year in five, and 0.0 MgC ha-1 y-1 for superficial tillage. Cover crops were estimated to store 0.24 (0.13-0.37) MgC ha-1 y-1 between cash crops and 0.49 (0.23-0.72) MgC ha-1 y-1 when associated with vineyards. Hedges (i.e 60 m ha-1) stored 0.15 (0.05-0.26) Mg C ha-1 y-1. Very few estimates were available for temperate agroforestry system, and we proposed a value of 1.01 (0.11-1.36) Mg C ha-1 y-1for C stored in soil and in the tree biomass for systems comprising 30-50 trees ha-1. Increasing the life time of temporary sown grassland increased C stocls by 0.11 (0.07-0.22) Mg C ha-1 y-1. In general, practices with increased C inputs to soil through

  9. Chemically assisted phytoextraction: a review of potential soil amendments for increasing plant uptake of heavy metals.

    Science.gov (United States)

    Meers, E; Tack, F M G; Van Slycken, S; Ruttens, A; Du Laing, G; Vangronsveld, J; Verloo, M G

    2008-01-01

    The contamination of soils by trace metals has been an unfortunate sideeffect of industrialization. Some of these contaminants can interfere with vulnerable enduses of soil, such as agriculture or nature, already at relatively low levels of contamination. Reversely, conventional civil-technical soil-remediation techniques are too expensive to remediate extended areas of moderately contaminated soil. Phytoextraction has been proposed as a more economic complementary approach to deal with this specific niche of soil contamination. However, phytoextraction has been shown to be a slow-working process due to the low amounts of metals that can be annually removed from the soil under normal agronomic conditions. Therefore, extensive research has been conducted on process optimization by means of chemically improving plant availability and the uptake of heavy metals. A wide range of potential amendments has been proposed in the literature, with considerable attention being spent on aminopolycarboxylic acids such as ethylenediaminetetraacetic acid (EDTA). However, these compounds have received increasing criticism due to their environmental persistence and associated risks for leaching. This review presents an overview of potential soil amendments that can be employed for enhancing metal uptake by phytoextraction crops, with a distinct focus on more degradable alternatives to persistent compounds such as EDTA.

  10. Hydrologic connectivity to streams increases nitrogen and phosphorus inputs and cycling in soils of created and natural floodplain wetlands.

    Science.gov (United States)

    Wolf, Kristin L; Noe, Gregory B; Ahn, Changwoo

    2013-07-01

    Greater connectivity to stream surface water may result in greater inputs of allochthonous nutrients that could stimulate internal nitrogen (N) and phosphorus (P) cycling in natural, restored, and created riparian wetlands. This study investigated the effects of hydrologic connectivity to stream water on soil nutrient fluxes in plots ( = 20) located among four created and two natural freshwater wetlands of varying hydrology in the Piedmont physiographic province of Virginia. Surface water was slightly deeper; hydrologic inputs of sediment, sediment-N, and ammonium were greater; and soil net ammonification, N mineralization, and N turnover were greater in plots with stream water classified as their primary water source compared with plots with precipitation or groundwater as their primary water source. Soil water-filled pore space, inputs of nitrate, and soil net nitrification, P mineralization, and denitrification enzyme activity (DEA) were similar among plots. Soil ammonification, N mineralization, and N turnover rates increased with the loading rate of ammonium to the soil surface. Phosphorus mineralization and ammonification also increased with sedimentation and sediment-N loading rate. Nitrification flux and DEA were positively associated in these wetlands. In conclusion, hydrologic connectivity to stream water increased allochthonous inputs that stimulated soil N and P cycling and that likely led to greater retention of sediment and nutrients in created and natural wetlands. Our findings suggest that wetland creation and restoration projects should be designed to allow connectivity with stream water if the goal is to optimize the function of water quality improvement in a watershed. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  11. Eisenia fetida increased removal of polycyclic aromatic hydrocarbons from soil

    Energy Technology Data Exchange (ETDEWEB)

    Contreras-Ramos, Silvia M. [Laboratory of Soil Ecology, Department of Biotechnology and Bioengineering, Cinvestav, Av. Instituto Politecnico Nacional 2508, C.P. 07000 Mexico, D.F. (Mexico); Alvarez-Bernal, Dioselina [Laboratory of Soil Ecology, Department of Biotechnology and Bioengineering, Cinvestav, Av. Instituto Politecnico Nacional 2508, C.P. 07000 Mexico, D.F. (Mexico); Dendooven, Luc [Laboratory of Soil Ecology, Department of Biotechnology and Bioengineering, Cinvestav, Av. Instituto Politecnico Nacional 2508, C.P. 07000 Mexico, D.F. (Mexico)]. E-mail: dendoove@cinvestav.mx

    2006-06-15

    The removal of phenanthrene, anthracene and benzo(a)pyrene added at three different concentrations was investigated with or without earthworms (Eisenia fetida) within 11 weeks. Average anthracene removal by the autochthonous micro-organisms was 23%, 77% for phenanthrene and 13% for benzo(a)pyrene, while it was 51% for anthracene, 47% for benzo(a)pyrene and 100% for phenanthrene in soil with earthworms. At 50 and 100 mg phenanthrene kg{sup -1} E. fetida survival was 91% and 83%, but at 150 mg kg{sup -1} all died within 15 days. Survival of E. fetida in soil amended with anthracene {<=}1000 mg kg{sup -1} and benzo(a)pyrene {<=}150 mg kg{sup -1} was higher than 80% and without weight loss compared to the untreated soil. Only small amounts of PAHs were detected in the earthworms. It was concluded that E. fetida has the potential to remove large amounts of PAHs from soil, but more work is necessary to elucidate the mechanisms involved. - Addition of earthworms, Eisenia fetida, accelara removal of polycyclic aromatic hydrocarbons from soil.

  12. Eisenia fetida increased removal of polycyclic aromatic hydrocarbons from soil

    International Nuclear Information System (INIS)

    Contreras-Ramos, Silvia M.; Alvarez-Bernal, Dioselina; Dendooven, Luc

    2006-01-01

    The removal of phenanthrene, anthracene and benzo(a)pyrene added at three different concentrations was investigated with or without earthworms (Eisenia fetida) within 11 weeks. Average anthracene removal by the autochthonous micro-organisms was 23%, 77% for phenanthrene and 13% for benzo(a)pyrene, while it was 51% for anthracene, 47% for benzo(a)pyrene and 100% for phenanthrene in soil with earthworms. At 50 and 100 mg phenanthrene kg -1 E. fetida survival was 91% and 83%, but at 150 mg kg -1 all died within 15 days. Survival of E. fetida in soil amended with anthracene ≤1000 mg kg -1 and benzo(a)pyrene ≤150 mg kg -1 was higher than 80% and without weight loss compared to the untreated soil. Only small amounts of PAHs were detected in the earthworms. It was concluded that E. fetida has the potential to remove large amounts of PAHs from soil, but more work is necessary to elucidate the mechanisms involved. - Addition of earthworms, Eisenia fetida, accelara removal of polycyclic aromatic hydrocarbons from soil

  13. The increase of the fertility of soils using the liquid organic fertilizers and fertilizers based on sugar-beet wastes.

    Science.gov (United States)

    Vyborova, Oxana

    2010-05-01

    The fertility of soil is a capacity for ensuring plants by water, nutrients, air and capacity for making optimal conditions for growth and development of plants. The result of it is a yield. The main characteristic of fertility of soil is maintenance of humus. The humus is important part of organic matter. The supporting of soil fertility is impossible by traditional methods. The amount of receiving mineral fertilizers in agriculture will not increase in future, because mineral fertilizers are very expensive. The mineral fertilizers don't influence on maintenance of total amount of humus in soil and improve the circulation of nutrients. Every hectare of fields have to receive no less than 8-10 tons of organic fertilizers, therefore we will have self-supporting balance of humus and the fertility of soils will be increasing. Consequently we are looking for new types of organic materials and we include them in modern agro technologies. One of them is an organomineral fertilizer (lignitic materials). The humic chemicals in the form of lignitic materials of natrium, potassium and ammonium are permitted for using them in agriculture at the beginning of 1984. The Department of agriculture in Russian Federation considered the problem of using humic chemicals and made a decision to use them on the fields of our country, because the lignitic materials can restore the fertility of our fields. The lignitic materials increase the amount of spore-forming bacteria, mold fungi and actinomycete. Therefore the organic decomposition occurs more strongly, the processes of humification increase the speed and the amount of humus rises in the soil. The new forming humus has a high biological activity and it improves chemical and physical soil properties. The addition of lignitic materials in soil activates different groups of microorganisms, which influence on mobilization of nutrients and transformation from potential to effective fertility. The inclusion of humic fertilizers improves

  14. Effects of soil amendment on soil characteristics and maize yield in Horqin Sandy Land

    Science.gov (United States)

    Zhou, L.; Liu, J. H.; Zhao, B. P.; Xue, A.; Hao, G. C.

    2016-08-01

    A 4-year experiment was conducted to investigate the inter-annual effects of sandy soil amendment on maize yield, soil water storage and soil enzymatic activities in sandy soil in Northeast China in 2010 to 2014. We applied the sandy soil amendment in different year, and investigated the different effects of sandy soil amendment in 2014. There were six treatments including: (1) no sandy soil amendment application (CK); (2) one year after applying sandy soil amendment (T1); (3) two years after applying sandy soil amendment(T2); (4) three years after applying sandy soil amendment(T3); (5)four years after applying sandy soil amendment(T4); (6) five years after applying sandy soil amendment (T5). T refers to treatment, and the number refers to the year after application of the sandy soil amendment. Comparing with CK, sandy soil amendments improved the soil water storage, soil urease, invertase, and catalase activity in different growth stages and soil layers, the order of soil water storage in all treatments roughly performed: T3 > T5 > T4 > T2 > T1 > CK. the order of soil urease, invertase, and catalase activity in all treatments roughly performed: T5 > T3 > T4 > T2 > T1 > CK. Soil application of sandy soil amendment significantly (p≤⃒0.05) increased the grain yield and biomass yield by 22.75%-41.42% and 29.92%-45.45% respectively, and maize yield gradually increased with the years go by in the following five years. Sandy soil amendment used in poor sandy soil had a positive effect on soil water storage, soil enzymatic activities and maize yield, after five years applied sandy soil amendment (T5) showed the best effects among all the treatments, and deserves further research.

  15. 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.

  16. Anaerobic N mineralization in paddy soils in relation to inundation management, physicochemical soil fractions, mineralogy and soil properties

    Science.gov (United States)

    Sleutel, Steven; Kader, Mohammed Abdul; Ara Begum, Shamim; De Neve, Stefaan

    2013-04-01

    Anaerobic N mineralization measured from (saturated) repacked soil cores from 25 paddy fields in Bangladesh and was previously found to negatively related to soil N content on a relative basis. This suggests that other factors like soil organic matter (SOM) quality or abiotic factors instead control the anaerobic N mineralization process. We therefore assessed different physical and chemical fractions of SOM, management factors and various soil properties as predictors for the net anaerobic N mineralization. 1° First, we assessed routinely analyzed soil parameters (soil N and soil organic carbon, texture, pH, oxalate- and pyrophosphate-extractable Fe, Al, and Mn, fixed-NH4 content). We found no significant influences of neither soil mineralogy nor the annual length of inundation on soil N mineralization. The anaerobic N mineralization correlated positively with Na-pyrophosphate-extractable Fe and negatively with pH (both at Presistant OM fraction, followed by extraction of mineral bound OM with 10%HF thereby isolating the HF-resistant OM. None of the physicochemical SOM fractions were found useful predictors anaerobic N mineralization. The linkage between these chemical soil N fractions and N supplying processes actually occurring in the soil thus appears to be weak. Regardless, we hypothesize that variation in strength of N-mineral and N-OM linkages is likely to explain variation in bio-availability of organic N and proneness to mineralization. Yet, in order to separate kinetically different soil N fractions we then postulated that an alternative approach would be required, which instead isolates soil N fractions on the basis of bonding strength. In this respect bonding strength should be seen as opposite of proneness to dissolution of released N into water, the habitat of soil microorganisms mediating soil N mineralization. We hypothesize that soil N extracted by water at increasing temperatures would reflect such N fractions with increasing bonding strength, in

  17. Efficiency of Syrian and Indian rock phosphates for maize in two soils amended with sulphur

    International Nuclear Information System (INIS)

    Kanacri, S.

    1995-01-01

    A greenhouse pot experiment was conducted to evaluate the fertilizer use efficiency of three Syrian rock phosphates in comparison to Mussoorie rock phosphate from India for maize grown in a laterite (ultisol) and an alluvial (entisol) soil amended with sulphur, and using sup 3 sup 2 P-labelled triple superphosphate (TSP). Results showed that application of rock phosphates (RPs) to laterite soil significantly increased the dry matter yields of maize shoots, whereas, in alluvial soil, RPs were not found effective in increasing the yields. Data further indicated that all the three Syrian RPs were equally efficient in increasing dry matter yields in laterite soil and were superior to Mussoorie rock phosphate (MRP). Sulphur added in combination with RPs significantly enhanced the dry matter production as well as 'A' value of alluvial soil. Application of sulphur in conjunction with RPs significantly increased the 'A' value of laterite soil however, sulphur did not contribute to any significant increase in the yields. Syrian RPs were more reactive in soils than Mussoorie RP. (author). 7 refs., 6 tabs

  18. Efficiency of Syrian and Indian rock phosphates for maize in two soils amended with sulphur

    International Nuclear Information System (INIS)

    Kanacri, Saloi; Bhujbal, B.M.

    1993-01-01

    A greenhouse pot experiment was conducted to evaluate the fertilizer use efficiency of three Syrian rock phosphates in comparison to Mussoorie rock phosphate from India for maize grown in a laterite (ultisol) and an alluvial (entisol) soil amended with sulphur, and using 32 P-labelled triple superphosphate (TSP). Results showed that application of rock phosphates (RPs) to laterite soil significantly increased the dry matter yields of maize shoots, whereas, in alluvial soil, RPs were not found effective in increasing the yields. Data further indicated that all the three Syrian RPs were equally efficient in increasing dry matter yields in laterite soil and were superior to Mussoorie rock phosphate (MRP). Sulphur added in combination with RPs significantly enhanced the dry matter production as well as 'A'value of alluvial soil. Application of sulphur in conjunction with RPs significantly increased the 'A' value of laterite soil, however, sulphur did not contribute to any significant increase in the yields. Syrian RPs were more reactive in soils than Mussoorie RP. (author). 7 refs., 6 tabs

  19. Influence of ameliorating soil acidity with dolomite on the priming of soil C content and CO2 emission.

    Science.gov (United States)

    Shaaban, Muhammad; Wu, Lei; Peng, Qi-An; van Zwieten, Lukas; Chhajro, Muhammad Afzal; Wu, Yupeng; Lin, Shan; Ahmed, Muhammad Mahmood; Khalid, Muhammad Salman; Abid, Muhammad; Hu, Ronggui

    2017-04-01

    Lime or dolomite is commonly implemented to ameliorate soil acidity. However, the impact of dolomite on CO 2 emissions from acidic soils is largely unknown. A 53-day laboratory study was carried out to investigate CO 2 emissions by applying dolomite to an acidic Acrisol (rice-rapeseed rotation [RR soil]) and a Ferralsol (rice-fallow/flooded rotation [RF soil]). Dolomite was dosed at 0, 0.5, and 1.5 g 100 g -1 soil, herein referred to as CK, L, and H, respectively. The soil pH (H2O) increased from 5.25 to 7.03 and 7.62 in L and H treatments of the RR soil and from 5.52 to 7.27 and 7.77 in L and H treatments of the RF soil, respectively. Dolomite application significantly (p ≤ 0.001) increased CO 2 emissions in both RR and RF soils, with higher emissions in H as compared to L dose of dolomite. The cumulative CO 2 emissions with H dose of dolomite were greater 136% in the RR soil and 149% in the RF soil as compared to CK, respectively. Dissolved organic carbon (DOC) and microbial biomass carbon (MBC) increased and reached at 193 and 431 mg kg -1 in the RR soil and 244 and 481 mg kg -1 in the RF soil by H treatments. The NH 4 - -N and NO 3 - -N were also increased by dolomite application. The increase in C and N contents stimulated microbial activities and therefore higher respiration in dolomite-treated soil as compared to untreated. The results suggest that CO 2 release in dolomite-treated soils was due to the priming of soil C content rather than chemical reactions.

  20. The use of pruned chipped branches to increase the soil infiltration capacity and reduce the soil losses on citrus orchards in Eastern Spain

    Science.gov (United States)

    González-Pelayo, Óscar; Llovet, Joan; Giménez-Morera, Antonio; Jordán, Antonio; Pereira, Paulo; Novara, Agata; García-Orenes, Fuensanta; Cerdà, Artemi

    2015-04-01

    Soil water erosion is causing problems on the agriculture land of the world. The high erosion rates registered in the agriculture land are due to the lack of a vegetation cover that protects the soil. High erosion rates in agriculture lands are found in Africa, Europe, Asia, and any other continent. Soil erosion on citrus orchards has been researched recently and shown huge erosion rates in the Mediterranean and in China. All this research findings allow us to confirm that the soil erosion rates on citrus orchards are not sustainable and strategies to control the soil erosion should be applied. The increasing erosion rates are due to the bare soils, but also are due to the soil structure degradation and soil organic matter exhaustion. Some authors applied cover on crops to avoid the raindrop impact and the surfaces wash but there is a need to develop new strategies to reduce soil losses and keep sustainable the citrus productions. The agriculture production also results in a large amount of residues than can be a resource to improve the soil cover. This has been done in road embankments, in forest land affected by wildfires and on afforestation. As a consequence of the mechanization of the agriculture, and the reduction of the draft animals (mainly horses, mules, donkeys and oxen), the straw and the pruned branches are being a residue instead of a resource in many developed countries. Straw was used as a forage and the pruned branches as a source of heat and energy but both can be used as a mulch to control the soil erosion. The pruned branches can contribute with a valuable source of nutrients and a good soil protection. The leaves of the trees, and some parts of the plants, once harvest can contribute to reduce the soil losses. Our goal is to test if a residue such as the chipped pruned branches can be transformed as a resource that will help to control the soil erosion rates. Straw has been seen as a very efficient to reduce the water losses in agriculture land

  1. Studies on the effect of irradiated soil on crop growth and its mechanism

    International Nuclear Information System (INIS)

    Wang Yanling; Zhu Shuxiu; Zulhayat, N.; Yang Yuai; Zhang Qinzheng

    1996-04-01

    Pot experiments showed that with the treatment of 25 kGy gamma radiation on the irrigated gray desert soil in Xinjiang and the moist soil in Zhejiang, 25% moisture, plant height, biomass and photosynthesis intensity of winter wheat, hot pepper and matrimony vine increased significantly. In irradiated soils of six types, the available N, P, K were significantly enhanced, and the available Fe, Zn, Cu increased to some extent, while the oxidation stability of the soil organo-mineral complex decreased dramatically. The amount of available N supplied by the irradiated gray desert soil and the moist soil increased by 59.26% and 82.35% respectively. The amount of N derived from the irradiated soils in crops also increased by 4.48% and 24.97% respectively. The amount of available P supplied by irradiated gray desert soil increased by 15.69%, and the P in crops derived from the irradiated gray desert soil increased by 34.00%. Utilization rate of N fertilizer were raised by 49.47% and 75.53% for irradiated gray desert soil and moist soil respectively, that of P fertilizer was raised by 17.88% for moist soil. The effect of radiation on soil showed little difference between treatments of 25 kGy and 35 kGy. However, soil moisture affected the radiation effect greatly. (7 refs., 2 figs., 12 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. Effects of Nitrogen and Water on Soil Enzyme Activity and Soil Microbial Biomass in Stipa baicalensis Steppe,Inner Mongolia of North China

    Directory of Open Access Journals (Sweden)

    WANG Jie

    2014-06-01

    Full Text Available In this paper, eight nitrogen treatments were applied at 0 g·m -2(N0, 1.5 g·m -2(N15, 3.0 g·m -2(N30, 5.0 g·m -2(N50, 10.0 g·m -2(N100, 15.0 g·m -2(N150, 20.0 g·m -2(N200, 30.0 g·m -2(N300 as NH 4 NO 3 and adding water to simulate summer rainfall of 100 mm, the interactive experiment was set to explore the effects of nitrogen and water addition in Stipa baicalensis steppe on soil nutrients, enzyme activities and soil microbial biomass. The results showed that the nitrogen and water addition changed soil physico-chemical factors obviously, the content of soil total organic carbon, total nitrogen, nitrate nitrogen and ammonium nitrogen increased along with the increasing of application rate of nitrogen, on the contrary, the soil pH value had decreasing trend. Appropriate application of nitrogen could enhance the activity of urease and catalase but decreased the activity of polyphenol oxidase. Nitrogen and water addition had significant effect on soil microbial biomass C and N. Higher level of N fertilizer significantly reduced microbial biomass C, and the microbial biomass N was on the rise with the application rate of nitrogen. The addition of water could slow the inhibition of nitrogen to microorganism and increase the microbial biomass C and N. A closed relationship existed in soil nutrient, activities of soil enzyme and soil microbial biomass C and N. The significantly positive correlation existed between total N, organic C, nitrate N and catalase, significantly negative correlation between nitrate N, ammonium N, total N and polyphenol oxidase. Microbial biomass N was significantly positive correlated with total N, nitrate N, ammonium N, catalase, phosphatase, and was negative correlated with polyphenol oxidase. Microbial biomass C was significantly positive correlated with polyphenol oxidase, and was negative correlated with catalase.

  4. [Effects of adding straw carbon source to root knot nematode diseased soil on soil microbial biomass and protozoa abundance].

    Science.gov (United States)

    Zhang, Si-Hui; Lian, Jian-Hong; Cao, Zhi-Ping; Zhao, Li

    2013-06-01

    A field experiment with successive planting of tomato was conducted to study the effects of adding different amounts of winter wheat straw (2.08 g x kg(-1), 1N; 4.16 g x kg(-1), 2N; and 8.32 g x kg(-1), 4N) to the soil seriously suffered from root knot nematode disease on the soil microbial biomass and protozoa abundance. Adding straw carbon source had significant effects on the contents of soil microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) and the abundance of soil protozoa, which all decreased in the order of 4N > 2N > 1N > CK. The community structure of soil protozoa also changed significantly under straw addition. In the treatments with straw addition, the average proportion of fagellate, amoeba, and ciliates accounted for 36.0%, 59.5%, and 4.5% of the total protozoa, respectively. Under the same adding amounts of wheat straw, there was an increase in the soil MBC and MBN contents, MBC/MBN ratio, and protozoa abundance with increasing cultivation period.

  5. 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

  6. Relation between soil temperature and biophysical parameters in Indian mustard seeds

    Science.gov (United States)

    Adak, T.; Chakravarty, N. V. K.

    2013-12-01

    Temporal changes in surface soil temperature were studied in winter crop. Significant changes in bare and cropped soil temperature were revealed. Air temperature showed a statistically positive and strong relationship (R2 = 0.79** to 0.92**) with the soil temperature both at morning and afternoon hours. Linear regression analysis indicated that each unit increase in ambient temperature would lead to increase in minimum and maximum soil temperatures by 1.04 and 1.02 degree, respectively. Statistically positive correlation was revealed among biophysical variables with the cumulative surface soil temperature. Linear and non-linear regression analysis indicated 62-69, 72-86 and 72-80% variation in Leaf area index, dry matter production and heat use efficiency in Indian mustard crop as a function of soil degree days. Below 60% variation in yield in Indian mustard was revealed as a function of soil temperature. In contrast, non-significant relationship between oil content and soil temperature was found, which suggests that oil accumulation in oilseed crops was not affected significantly by the soil temperature as an independent variable.

  7. Hydrologic connectivity to streams increases nitrogen and phosphorus inputs and cycling in soils of created and natural floodplain wetlands

    Science.gov (United States)

    Wolf, Kristin L.; Noe, Gregory; Ahn, Changwoo

    2013-01-01

    Greater connectivity to stream surface water may result in greater inputs of allochthonous nutrients that could stimulate internal nitrogen (N) and phosphorus (P) cycling in natural, restored, and created riparian wetlands. This study investigated the effects of hydrologic connectivity to stream water on soil nutrient fluxes in plots (n = 20) located among four created and two natural freshwater wetlands of varying hydrology in the Piedmont physiographic province of Virginia. Surface water was slightly deeper; hydrologic inputs of sediment, sediment-N, and ammonium were greater; and soil net ammonification, N mineralization, and N turnover were greater in plots with stream water classified as their primary water source compared with plots with precipitation or groundwater as their primary water source. Soil water-filled pore space, inputs of nitrate, and soil net nitrification, P mineralization, and denitrification enzyme activity (DEA) were similar among plots. Soil ammonification, N mineralization, and N turnover rates increased with the loading rate of ammonium to the soil surface. Phosphorus mineralization and ammonification also increased with sedimentation and sediment-N loading rate. Nitrification flux and DEA were positively associated in these wetlands. In conclusion, hydrologic connectivity to stream water increased allochthonous inputs that stimulated soil N and P cycling and that likely led to greater retention of sediment and nutrients in created and natural wetlands. Our findings suggest that wetland creation and restoration projects should be designed to allow connectivity with stream water if the goal is to optimize the function of water quality improvement in a watershed.

  8. Soil degradation effect on biological activity in Mediterranean calcareous soils

    Science.gov (United States)

    Roca-Pérez, L.; Alcover-Sáez, S.; Mormeneo, S.; Boluda, R.

    2009-04-01

    Soil degradation processes include erosion, organic matter decline, compaction, salinization, landslides, contamination, sealing and biodiversity decline. In the Mediterranean region the climatological and lithological conditions, together with relief on the landscape and anthropological activity are responsible for increasing desertification process. It is therefore considered to be extreme importance to be able to measure soil degradation quantitatively. We studied soil characteristics, microbiological and biochemical parameters in different calcareous soil sequences from Valencia Community (Easter Spain), in an attempt to assess the suitability of the parameters measured to reflect the state of soil degradation and the possibility of using the parameters to assess microbiological decline and soil quality. For this purpose, forest, scrubland and agricultural soil in three soil sequences were sampled in different areas. Several sensors of the soil biochemistry and microbiology related with total organic carbon, microbial biomass carbon, soil respiration, microorganism number and enzyme activities were determined. The results show that, except microorganism number, these parameters are good indicators of a soil biological activity and soil quality. The best enzymatic activities to use like indicators were phosphatases, esterases, amino-peptidases. Thus, the enzymes test can be used as indicators of soil degradation when this degradation is related with organic matter losses. There was a statistically significant difference in cumulative O2 uptake and extracellular enzymes among the soils with different degree of degradation. We would like to thank Spanish government-MICINN for funding and support (MICINN, project CGL2006-09776).

  9. 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

  10. Isolation and identification of soil fungi isolates from forest soil for flooded soil recovery

    Science.gov (United States)

    Hazwani Aziz, Nor; Zainol, Norazwina

    2018-04-01

    Soil fungi have been evaluated for their ability in increasing and recovering nitrogen, phosphorus and potassium content in flooded soil and in promoting the growth of the host plant. Host plant was cultivated in a mixture of fertile forest soil (nutrient-rich soil) and simulated flooded soil (nutrient-poor soil) in an optimized soil condition for two weeks. The soil sample was harvested every day until two weeks of planting and was tested for nitrogen, phosphorus and potassium concentration. Soil fungi were isolated by using dilution plating technique and was identified by Biolog’s Microbial Systems. The concentration of nitrogen, phosphorus, and potassium was found to be increasing after two weeks by two to three times approximately from the initial concentration recorded. Two fungi species were identified with probability more than 90% namely Aspergillus aculeatus and Paecilomyces lilacinus. Both identified fungi were found to be beneficial in enhancing plant growth and increasing the availability of nutrient content in the soil and thus recovering the nutrient content in the flooded soil.

  11. 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.

  12. Effects of EDTA and low molecular weight organic acids on soil solution properties of a heavy metal polluted soil.

    Science.gov (United States)

    Wu, L H; Luo, Y M; Christie, P; Wong, M H

    2003-02-01

    A pot experiment was conducted to study the effects of EDTA and low molecular weight organic acids (LMWOA) on the pH, total organic carbon (TOC) and heavy metals in the soil solution in the rhizosphere of Brassica juncea grown in a paddy soil contaminated with Cu, Zn, Pb and Cd. The results show that EDTA and LMWOA have no effect on the soil solution pH. EDTA addition significantly increased the TOC concentrations in the soil solution. The TOC concentrations in treatments with EDTA were significantly higher than those in treatments with LMWOA. Adding 3 mmol kg(-1) EDTA to the soil markedly increased the total concentrations of Cu, Zn, Pb and Cd in the soil solution. Compared to EDTA, LMWOA had a very small effect on the metal concentrations. Total concentrations in the soil solution followed the sequence: EDTA > citric acid (CA) approximately oxalic acid (OA) approximately malic acid (MA) for Cu and Pb; EDTA > MA > CA approximately OA for Zn; and EDTA > MA > CA > OA for Cd. The labile concentrations of Cu, Zn, Pb and Cd showed similar trends to the total concentrations.

  13. Rice straw incorporated just before soil flooding increases acetic acid formation and decreases available nitrogen

    Directory of Open Access Journals (Sweden)

    Ronaldir Knoblauch

    2014-02-01

    before, the concentration of N-NH4+ in the soil was 28 and 54 mg kg-1, equivalent to an accumulation of 42 and 81 kg ha-1 of N-NH4+, respectively. There was formation of acetic acid in which toxic concentrations were reached (7.2 mmol L-1 on the 15th day of flooding only for the treatment with straw incorporated on the day of flooding. The pH of the soil solution of all the treatments increased after flooding and this increase was faster in the treatments with incorporation of straw, followed by the ash treatment and then the control. After 60 days of flooding, however, the pH values were around 6.5 for all treatments, except for the control, which reached a pH of 6.3. Rice straw should be incorporated into the soil at least 30 days before flooding; otherwise, it may immobilize part of the mineral N and produce acetic acid in concentrations toxic to rice seedlings.

  14. Effects of Soil Compaction on Carbon and Nitrogen Sequestration in Soil and Wheat, Soil Physical Properties and Aggregates Stability (Case study: Northern of Aq Qala

    Directory of Open Access Journals (Sweden)

    Z. Saieedifar

    2016-09-01

    . Results and Discussion: The results showed that the different levels of soil compaction significantly increased soil bulk density. All the soil compaction treatments have caused a significant reduction on carbon and nitrogen sequestration in soil and wheat, soil aggregates stability and saturated soil moisture values. In the other hand the amount of soil pH and EC has increased significantly by increasing soil compaction levels that Indicates the negative effect of compaction on salinization of arable land. Conclusion: The results of this study showed that the negative effects of soil compaction on soil physiochemical attributes are dependent on escalation of compaction. In total, even low levels of soil compaction (the treatment of two passes of a heavy tractor is able to remarkably alter soil physiochemical attributes and thus carbon and nitrogen sequestration in soil and wheat. Induced changes in nitrogen and carbon sequestration levels are important for who concerned of global warming and climate change. Regarding the inability of deactivating soil compaction adverse effects in the deep soil layers of agricultural fields is the best way of handling and preventing soil compaction. Using these sluggish renewable resources should be consistence with land capability and its physical nature. This type of land use will result in sustainable development. From the remarks given here, it might be concluded that revising agricultural regimes and production methods is inevitable. On this ground, revisiting current agricultural systems should be considered and an urgent demand for state-of-the-art methods consistent with environmental objectives is being felt. To prevent soil compaction as much as possible, tractors and machinery traffic must be avoided to an acceptable level and this is of high priority during the time which soil is wet. It is more preferable to perform the operations with lighter machineries. As much as possible in a sophisticated agricultural plan these

  15. The utilization of ultisol soil for horticulture crops cultivation

    Science.gov (United States)

    Sumono; Parinduri, SM; Huda, N.; Ichwan, N.

    2018-02-01

    Ultisol soil is a marginal soil commonly used for palm oil cultivation in Indonesia, its very potential for cultivation of horticulture crops. The utilization of ultisol soil can be done with adding compost with certain proportions. The research aimed to know best proportion of ultisol soil and compost, and proportion of water concentration, and its relationship with fresh and dry weight of horticulture crops . The research was divided 3 steps. The first, mixed ultisol soil and compost with certain proportion and flooding until steady. The second, watering with different concentration to soil mixture. The last, studied its relationship with fresh and dry weight of crops. The result show that physical properties and nutrient content of ultisol soil was increasing with adding compost. SC4 (70% soil and 30% compost) is the best composition to soil mixture. Watering with different concentration show that trend decreased from reference and the bulk density and porosity decreased not significantly at the significant level ∝ = 0.05. Watering affect mass of pakcoynot significantly at the significant level ∝ = 0.05. Hence, ultisol soil was a potential marginal soil to utilizing as a media for cultivating horticulture crops.

  16. Incorporation of Biochar Carbon into Stable Soil Aggregates: The Role of Clay Mineralogy and Other Soil Characteristics

    Institute of Scientific and Technical Information of China (English)

    Charlene N.KELLY; Joseph BENJAMIN; Francisco C.CALDER(O)N; Maysoon M.MIKHA; David W.RUTHERFORD; Colleen E.ROSTAD

    2017-01-01

    Aggregation and structure plav key roles in water-holding capacity and stability of soils.In this study,the incorporation of carbon (C) from switchgrass biochar into stable aggregate size fractions was assessed in an Aridisol (from Colorado,USA) dominated by 2:1 clays and an Alfisol (from Virginia,USA) containing weathered mixed 1∶1 and 2∶1 mineralogy,to evaluate the effect of biochar addition on soil characteristics.The biochar was applied at 4 levels,0,25,50,and 100 g kg-1,to the soils grown with wheat in a growth chamber experiment.The changes in soil strength and water-holding capacity using water release curves were measured.In the Colorado soil,the proportion of soil occurring in large aggregates decreased,with concomitant increases in small size fractions.No changes in aggregate size fractions occurred in the Virginia soil.In the Colorado soil,C content increased from 3.3 to 16.8 g kg-1,whereas in the < 53 μm fraction C content increased from 5.7 to 22.6 g kg-1 with 100 g kg-1 biochar addition.In the Virginia soil,C content within aggregate size fractions increased for each size fraction,except the > 2 000 μm fraction.The greatest increase (from 6.2 to 22.0 g kg-1) occurred in the 53-250 μm fraction.The results indicated that C was incorporated into larger aggregates in the Virginia soil,but remained largely unassociated to soil particles in the Colorado soil.Biochar addition had no significant effect on water-holding capacity or strength measurements.Adding biochar to more weathered soils with high native soil organic content may result in greater stabilization of incorporated C and result in less loss because of erosion and transport,compared with the soils dominated by 2∶1 clays and low native soil organic content.

  17. Arbuscular mycorrhiza alters metal uptake and the physiological response of Coffea arabica seedlings to increasing Zn and Cu concentrations in soil.

    Science.gov (United States)

    Andrade, S A L; Silveira, A P D; Mazzafera, P

    2010-10-15

    Studies on mycorrhizal symbiosis effects on metal accumulation and plant tolerance are not common in perennial crops under metal stress. The objective of this study was to evaluate the influence of mycorrhization on coffee seedlings under Cu and Zn stress. Copper (Cu) and zinc (Zn) uptake and some biochemical and physiological traits were studied in thirty-week old Coffea arabica seedlings, in response to the inoculation with arbuscular mycorrhizal fungi (AMF) and to increasing concentrations of Cu or Zn in soil. The experiments were conducted under greenhouse conditions in a 2×4 factorial design (inoculation or not with AMF and 0, 50, 150 and 450mgkg(-1) Cu or 0, 100, 300 and 900mgkg(-1) Zn). Non-mycorrhizal plants maintained a hampered and slow growth even in a soil with appropriate phosphorus (P) levels for this crop. As metal levels increased in soil, a greater proportion of the total absorbed metals were retained by roots. Foliar Cu concentrations increased only in non-mycorrhizal plants, reaching a maximum concentration of 30mgkg(-1) at the highest Cu in soil. Mycorrhization prevented the accumulation of Cu in leaves, and mycorrhizal plants showed higher Cu contents in stems, which indicated a differential Cu distribution in AMF-associated or non-associated plants. Zn distribution and concentrations in different plant organs followed a similar pattern independently of mycorrhization. In mycorrhizal plants, only the highest metal concentrations caused a reduction in biomass, leading to significant changes in some biochemical indicators, such as malondialdehyde, proline and amino acid contents in leaves and also in foliar free amino acid composition. Marked differences in these physiological traits were also found due to mycorrhization. In conclusion, AMF protected coffee seedlings against metal toxicity. Copyright © 2010 Elsevier B.V. All rights reserved.

  18. Effect of restoring soil hydrological poperties on water conservation

    NARCIS (Netherlands)

    Moore, D.; Kostka, S.J.; Boerth, T.J.; Franklin, M.A.; Ritsema, C.J.; Dekker, L.W.; Oostindie, K.; Stoof, C.R.; Park, D.M.

    2008-01-01

    Water repellency in soil is more wide spread than previously thought ¿ and has a significant impact on irrigation efficiency and water conservation. Soil water repellency has been identified in many soil types under a wide array of climatic conditions world wide. Consequences include increased

  19. Global soil-climate-biome diagram: linking soil properties to climate and biota

    Science.gov (United States)

    Zhao, X.; Yang, Y.; Fang, J.

    2017-12-01

    As a critical component of the Earth system, soils interact strongly with both climate and biota and provide fundamental ecosystem services that maintain food, climate, and human security. Despite significant progress in digital soil mapping techniques and the rapidly growing quantity of observed soil information, quantitative linkages between soil properties, climate and biota at the global scale remain unclear. By compiling a large global soil database, we mapped seven major soil properties (bulk density [BD]; sand, silt and clay fractions; soil pH; soil organic carbon [SOC] density [SOCD]; and soil total nitrogen [STN] density [STND]) based on machine learning algorithms (regional random forest [RF] model) and quantitatively assessed the linkage between soil properties, climate and biota at the global scale. Our results demonstrated a global soil-climate-biome diagram, which improves our understanding of the strong correspondence between soils, climate and biomes. Soil pH decreased with greater mean annual precipitation (MAP) and lower mean annual temperature (MAT), and the critical MAP for the transition from alkaline to acidic soil pH decreased with decreasing MAT. Specifically, the critical MAP ranged from 400-500 mm when the MAT exceeded 10 °C but could decrease to 50-100 mm when the MAT was approximately 0 °C. SOCD and STND were tightly linked; both increased in accordance with lower MAT and higher MAP across terrestrial biomes. Global stocks of SOC and STN were estimated to be 788 ± 39.4 Pg (1015 g, or billion tons) and 63 ± 3.3 Pg in the upper 30-cm soil layer, respectively, but these values increased to 1654 ± 94.5 Pg and 133 ± 7.8 Pg in the upper 100-cm soil layer, respectively. These results reveal quantitative linkages between soil properties, climate and biota at the global scale, suggesting co-evolution of the soil, climate and biota under conditions of global environmental change.

  20. Soil mulching significantly enhances yields and water and nitrogen use efficiencies of maize and wheat

    NARCIS (Netherlands)

    Qin, Wei; Hu, Chunsheng; Oenema, Oene

    2015-01-01

    Global crop yields are limited by water and nutrient availability. Soil mulching (with plastic or straw) reduces evaporation, modifies soil temperature and thereby affects crop yields. Reported effects of mulching are sometimes contradictory, likely due to differences in climatic conditions, soil

  1. Contrasting effects of untreated textile wastewater onto the soil available nitrogen-phosphorus and enzymatic activities in aridisol.

    Science.gov (United States)

    Arif, Muhammad Saleem; Riaz, Muhammad; Shahzad, Sher Muhammad; Yasmeen, Tahira; Buttler, Alexandre; Garcıa-Gil, Juan Carlos; Roohi, Mahnaz; Rasool, Akhtar

    2016-02-01

    Water shortage and soil qualitative degradation are significant environmental problems in arid and semi-arid regions of the world. The increasing demand for water in agriculture and industry has resulted in the emergence of wastewater use as an alternative in these areas. Textile wastewater is produced in surplus amounts which poses threat to the environment as well as associated flora and fauna. A 60-day incubation study was performed to assess the effects of untreated textile wastewater at 0, 25, 50, 75, and 100% dilution levels on the physico-chemical and some microbial and enzymatic properties of an aridisol soil. The addition of textile wastewater provoked a significant change in soil pH and electrical conductivity and soil dehydrogenase and urease activities compared to the distilled-water treated control soil. Moreover, compared to the control treatment, soil phosphomonoesterase activity was significantly increased from 25 to 75% application rates, but decreased at 100% textile wastewater application rate. Total and available soil N contents increased significantly in response to application of textile wastewater. Despite significant increases in the soil total P contents after the addition of textile wastewater, soil available P content decreased with increasing concentration of wastewater. Changes in soil nutrient contents and related enzymatic activities suggested a dynamic match between substrate availability and soil N and P contents. Aridisols have high fixation and low P availability, application of textile wastewater to such soils should be considered only after careful assessment.

  2. Effect of reclamation on soil organic carbon pools in coastal areas of eastern China

    Science.gov (United States)

    Li, Jianguo; Yang, Wenhui; Li, Qiang; Pu, Lijie; Xu, Yan; Zhang, Zhongqi; Liu, Lili

    2018-06-01

    The coastal wetlands of eastern China form one of the most important carbon sinks in the world. However, reclamation can significantly alter the soil carbon pool dynamics in these areas. In this study, a chronosequence was constructed for four reclamation zones in Rudong County, Jiangsu Province, eastern China (reclaimed in 1951, 1974, 1982, and 2007) and a reference salt marsh to identify both the process of soil organic carbon (SOC) evolution, as well as the effect of cropping and soil properties on SOC with time after reclamation. The results show that whereas soil nutrient elements and SOC increased after reclamation, the electrical conductivity of the saturated soil extract (ECe), pH, and bulk density decreased within 62 years following reclamation and agricultural amendment. In general, the soil's chemical properties remarkably improved and SOC increased significantly for approximately 30 years after reclamation. Reclamation for agriculture (rice and cotton) significantly increased the soil organic carbon density (SOCD) in the top 60 cm, especially in the top 0-30 cm. However, whereas the highest concentration of SOCD in rice-growing areas was in the top 0-20 cm of the soil profile, it was greater at a 20-60 cm depth in cottongrowing areas. Reclamation also significantly increased heavy fraction organic carbon (HFOC) levels in the 0-30 cm layer, thereby enhancing the stability of the soil carbon pool. SOC can thus increase significantly over a long time period after coastal reclamation, especially in areas of cultivation, where coastal SOC pools in eastern China tend to be more stable.

  3. Effect of reclamation on soil organic carbon pools in coastal areas of eastern China

    Science.gov (United States)

    Li, Jianguo; Yang, Wenhui; Li, Qiang; Pu, Lijie; Xu, Yan; Zhang, Zhongqi; Liu, Lili

    2018-04-01

    The coastal wetlands of eastern China form one of the most important carbon sinks in the world. However, reclamation can significantly alter the soil carbon pool dynamics in these areas. In this study, a chronosequence was constructed for four reclamation zones in Rudong County, Jiangsu Province, eastern China (reclaimed in 1951, 1974, 1982, and 2007) and a reference salt marsh to identify both the process of soil organic carbon (SOC) evolution, as well as the effect of cropping and soil properties on SOC with time after reclamation. The results show that whereas soil nutrient elements and SOC increased after reclamation, the electrical conductivity of the saturated soil extract (ECe), pH, and bulk density decreased within 62 years following reclamation and agricultural amendment. In general, the soil's chemical properties remarkably improved and SOC increased significantly for approximately 30 years after reclamation. Reclamation for agriculture (rice and cotton) significantly increased the soil organic carbon density (SOCD) in the top 60 cm, especially in the top 0-30 cm. However, whereas the highest concentration of SOCD in rice-growing areas was in the top 0-20 cm of the soil profile, it was greater at a 20-60 cm depth in cottongrowing areas. Reclamation also significantly increased heavy fraction organic carbon (HFOC) levels in the 0-30 cm layer, thereby enhancing the stability of the soil carbon pool. SOC can thus increase significantly over a long time period after coastal reclamation, especially in areas of cultivation, where coastal SOC pools in eastern China tend to be more stable.

  4. Wetting properties of fungi mycelium alter soil infiltration and soil water repellency in a γ-sterilized wettable and repellent soil.

    Science.gov (United States)

    Chau, Henry Wai; Goh, Yit Kheng; Vujanovic, Vladimir; Si, Bing Cheng

    2012-12-01

    Soil water repellency (SWR) has a drastic impact on soil quality resulting in reduced infiltration, increased runoff, increased leaching, reduced plant growth, and increased soil erosion. One of the causes of SWR is hydrophobic fungal structures and exudates that change the soil-water relationship. The objective of this study was to determine whether SWR and infiltration could be manipulated through inoculation with fungi. The effect of fungi on SWR was investigated through inoculation of three fungal strains (hydrophilic -Fusarium proliferatum, chrono-amphiphilic -Trichoderma harzianum, and hydrophobic -Alternaria sp.) on a water repellent soil (WR-soil) and a wettable soil (W-soil). The change in SWR and infiltration was assessed by the water repellency index and cumulative infiltration respectively. F. proliferatum decreased the SWR on WR-soil and slightly increased SWR in W-soil, while Alternaria sp. increased SWR in both the W-soil and the WR-soil. Conversely T. harzianum increased the SWR in the W-soil and decreased the SWR in the WR-soil. All strains showed a decrease in infiltration in W-soil, while only the F. proliferatum and T. harzianum strain showed improvement in infiltration in the WR-soil. The ability of fungi to alter the SWR and enmesh soil particles results in changes to the infiltration dynamics in soil. Copyright © 2012 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  5. Effects of lead contamination on soil microbial activity and rice physiological indices in soil-Pb-rice (Oryza sativa L.) system.

    Science.gov (United States)

    Zeng, Lu-Sheng; Liao, Min; Chen, Cheng-Li; Huang, Chang-Yong

    2006-10-01

    The effect of lead (Pb) treatment on the soil microbial activities (soil microbial biomass and soil basal respiration) and rice physiological indices were studied by greenhouse pot experiment. Pb was applied as lead acetate at six different levels in two different paddy soils, namely 0 (control), 100, 300, 500, 700, 900 mg kg-1 soil. The results showed that the application of Pb at lower level (500 mg Pb kg-1 soil), which might be the critical concentration of Pb causing a significant decline in the soil microbial activities. However, the degree of influence on soil microbial activities by Pb was related to the clay and organic matter contents of the soils. On the other hand, when the level of Pb treatments increased to 500 mg kg-1, there was ecological risk for both soil microbial activities and plants. The results also revealed that there was a consistent trend that the chlorophyll contents increased initially, and then decreased gradually with increase in Pb concentration. Pb was effective in inducing proline accumulation and its toxicity causes oxidative stress in rice plants. In a word, soil microbial activities and rice physiological indices, therefore, may be sensitive indicators reflecting environmental stress in soil-Pb-rice system.

  6. Effect of charcoal amendment on adsorption, leaching and degradation of isoproturon in soils

    Science.gov (United States)

    Si, Youbin; Wang, Midao; Tian, Chao; Zhou, Jing; Zhou, Dongmei

    2011-04-01

    The effects of charcoal amendment on adsorption, leaching and degradation of the herbicide isoproturon in soils were studied under laboratory conditions. The adsorption data all fitted well with the Freundlich empirical equation. It was found that the adsorption of isoproturon in soils increased with the rate of charcoal amended (correlation coefficient r = 0.957 **, P isoproturon in leachate decreased with the increase of the amount of charcoal addition to soil column, while the retention of isoproturon in soils increased with an increase in the charcoal content of soil samples. Biodegradation was still the most significant mechanism for isoproturon dissipation from soil. Charcoal amendment greatly reduced the biodegradation of isoproturon in soils. The half-lives of isoproturon degradation ( DT50) in soils greatly extended when the rate of added charcoal inceased from 0 to 50 g kg - 1 (for Paddy soil, DT50 values increased from 54.6 to 71.4 days; for Alfisol, DT50 from 16.0 to 136 days; and for Vertisol, DT50 from 15.2 to 107 days). The degradation rate of isoproturon in soils was significantly negatively correlated with the amount of added charcoal. This research suggests that charcoal amendment may be an effective management practice for reducing pesticide leaching and enhancing its persistence in soils.

  7. Long-term manure amendments reduced soil aggregate stability via redistribution of the glomalin-related soil protein in macroaggregates

    Science.gov (United States)

    Xie, Hongtu; Li, Jianwei; Zhang, Bin; Wang, Lianfeng; Wang, Jingkuan; He, Hongbo; Zhang, Xudong

    2015-01-01

    Glomalin-related soil protein (GRSP) contributes to the formation and maintenance of soil aggregates, it is however remains unclear whether long-term intensive manure amendments alter soil aggregates stability and whether GRSP regulates these changes. Based on a three-decade long fertilization experiment in northeast China, this study examined the impact of long-term manure input on soil organic carbon (SOC), total and easily extractable GRSP (GRSPt and GRSPe) and their respective allocations in four soil aggregates (>2000 μm; 2000–250 μm; 250–53 μm; and soil and SOC in each aggregate generally increased with increasing manure input, GRSPt and GRSPe in each aggregate showed varying changes with manure input. Both GRSP in macroaggregates (2000–250 μm) were significantly higher under low manure input, a pattern consistent with changes in soil aggregate stability. Constituting 38~49% of soil mass, macroaggregates likely contributed to the nonlinear changes of aggregate stability under manure amendments. The regulatory process of GRSP allocations in soil aggregates has important implications for manure management under intensive agriculture. PMID:26423355

  8. Soil and plant response to used potassium silicate drilling fluid application.

    Science.gov (United States)

    Yao, Linjun; Anne Naeth, M

    2015-10-01

    Use of drilling waste generated from the oil and gas industry for land reclamation has potential to be a practical and economical means to improve soil fertility and to decrease landfills. A four month greenhouse experiment with common barley (Hordeum vulgare L.) on three different textured soils was conducted to determine soil and plant response to incorporated or sprayed potassium silicate drilling fluid (PSDF). Two PSDF types (used once, used twice) were applied at six rates (10, 20, 30, 40, 60, 120m(3)ha(-1)) as twelve PSDF amendments plus a control (non PSDF). Effects of PSDF amendment on plant properties were significant, and varied through physiological growth stages. Barley emergence and below ground biomass were greater with used once than used twice PSDF at the same application rate in clay loam soil. Used twice PSDF at highest rates significantly increased barley above ground biomass relative to the control in loam and sand soil. All PSDF treatments significantly increased available potassium relative to the control in all three soils. Soil electrical conductivity and sodium adsorption ratio increased with PSDF addition, but not to levels detrimental to barley. Soil quality rated fair to poor with PSDF amendments in clay loam, and reduced plant performance at the highest rate, suggesting a threshold beyond which conditions are compromised with PSDF utilization. PSDF application method did not significantly affect plant and soil responses. This initial greenhouse research demonstrates that PSDF has potential as a soil amendment for reclamation, with consideration of soil properties and plant species tolerances to determine PSDF types and rates to be used. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Eisenia fetida increased removal of polycyclic aromatic hydrocarbons from soil

    Energy Technology Data Exchange (ETDEWEB)

    Silvia M. Contreras-Ramos; Dioselina Alvarez-Bernal; Luc Dendooven [Laboratory of Soil Ecology, Department of Biotechnology and Bioengineering, Mexico (Mexico)

    2006-06-15

    The removal of phenanthrene, anthracene and benzo(a)pyrene added at three different concentrations was investigated with or without earthworms (Eisenia fetida) within 11 weeks. Average anthracene removal by the autochthonous micro-organisms was 23%, 77% for phenanthrene and 13% for benzo(a)pyrene, while it was 51% for anthracene, 47% for benzo(a)pyrene and 100% for phenanthrene in soil with earthworms. At 50 and 100 mg phenanthrene kg{sup -1} E. fetida survival was 91% and 83%, but at 150 mg kg{sup -1} all died within 15 days. Survival of E. fetida in soil amended with anthracene {<=}1000 mg kg{sup -1} and benzo(a)pyrene {<=}150 mg kg{sup -1} was higher than 80% and without weight loss compared to the untreated soil. Only small amounts of PAHs were detected in the earthworms. It was concluded that E. fetida has the potential to remove large amounts of PAHs from soil, but more work is necessary to elucidate the mechanisms involved.

  10. Dryland soil microbial communities display spatial biogeographic patterns associated with soil depth and soil parent material

    Science.gov (United States)

    Steven, Blaire; Gallegos-Graves, La Verne; Belnap, Jayne; Kuske, Cheryl R.

    2013-01-01

    Biological soil crusts (biocrusts) are common to drylands worldwide. We employed replicated, spatially nested sampling and 16S rRNA gene sequencing to describe the soil microbial communities in three soils derived from different parent material (sandstone, shale, and gypsum). For each soil type, two depths (biocrusts, 0–1 cm; below-crust soils, 2–5 cm) and two horizontal spatial scales (15 cm and 5 m) were sampled. In all three soils, Cyanobacteria and Proteobacteria demonstrated significantly higher relative abundance in the biocrusts, while Chloroflexi and Archaea were significantly enriched in the below-crust soils. Biomass and diversity of the communities in biocrusts or below-crust soils did not differ with soil type. However, biocrusts on gypsum soil harbored significantly larger populations of Actinobacteria and Proteobacteria and lower populations of Cyanobacteria. Numerically dominant operational taxonomic units (OTU; 97% sequence identity) in the biocrusts were conserved across the soil types, whereas two dominant OTUs in the below-crust sand and shale soils were not identified in the gypsum soil. The uniformity with which small-scale vertical community differences are maintained across larger horizontal spatial scales and soil types is a feature of dryland ecosystems that should be considered when designing management plans and determining the response of biocrusts to environmental disturbances.

  11. Impacts of Biochar on Physical Properties and Erosion Potential of a Mudstone Slopeland Soil

    Directory of Open Access Journals (Sweden)

    Zeng-Yei Hseu

    2014-01-01

    Full Text Available Food demand and soil sustainability have become urgent issues recently because of the global climate changes. This study aims to evaluate the application of a biochar produced by rice hull, on changes of physiochemical characteristics and erosion potential of a degraded slopeland soil. Rice hull biochar pyrolized at 400°C was incorporated into the soil at rates of 2.5%, 5%, and 10% (w/w and was incubated for 168 d in this study. The results indicated that biochar application reduced the Bd by 12% to 25% and the PR by 57% to 92% after incubation, compared with the control. Besides, porosity and aggregate size increased by 16% to 22% and by 0.59 to 0.94 mm, respectively. The results presented that available water contents significantly increased in the amended soils by 18% to 89% because of the obvious increase of micropores. The water conductivity of the biochar-amended soils was only found in 10% biochar treatment, which might result from significant increase of macropores and reduction of soil strength (Bd and PR. During a simulated rainfall event, soil loss contents significantly decreased by 35% to 90% in the biochar-amended soils. In conclusion, biochar application could availably raise soil quality and physical properties for tilth increasing in the degraded mudstone soil.

  12. Impacts of Biochar on Physical Properties and Erosion Potential of a Mudstone Slopeland Soil

    Science.gov (United States)

    Chien, Wei-Hsin; Liou, Ruei-Cheng

    2014-01-01

    Food demand and soil sustainability have become urgent issues recently because of the global climate changes. This study aims to evaluate the application of a biochar produced by rice hull, on changes of physiochemical characteristics and erosion potential of a degraded slopeland soil. Rice hull biochar pyrolized at 400°C was incorporated into the soil at rates of 2.5%, 5%, and 10% (w/w) and was incubated for 168 d in this study. The results indicated that biochar application reduced the Bd by 12% to 25% and the PR by 57% to 92% after incubation, compared with the control. Besides, porosity and aggregate size increased by 16% to 22% and by 0.59 to 0.94 mm, respectively. The results presented that available water contents significantly increased in the amended soils by 18% to 89% because of the obvious increase of micropores. The water conductivity of the biochar-amended soils was only found in 10% biochar treatment, which might result from significant increase of macropores and reduction of soil strength (Bd and PR). During a simulated rainfall event, soil loss contents significantly decreased by 35% to 90% in the biochar-amended soils. In conclusion, biochar application could availably raise soil quality and physical properties for tilth increasing in the degraded mudstone soil. PMID:25548787

  13. Effects of reduced soil functionality in European vineyards

    Science.gov (United States)

    Costantini, Edoardo; Priori, Simone; Akca, Ehran; Castaldini, Maurizio; D'Avino, Lorenzo; Fulchin, Emma; Gagnarli, Elena; Giffard, Brice; Erdem Kiraz, Mehmet; Lagomarsino, Alessandra; Landi, Silvia; Pellegrini, Sergio; Perria, Rita; Puccioni, Sergio; Schroers, Hans-Josef; Tardaguila, Javier; Pelengić, Radojko; Simoni, Sauro; Storchi, Paolo; Tangolar, Semih

    2017-04-01

    Improper or excessive land preparation methods in vineyards before planting can have a considerable impact on soil functionality. They include excessive levelling and deep ploughing leading to disturbances of the natural contour of slopes and destruction, truncation and burial of soil horizons. Manipulations may significantly modify chemical, physical, biological and hydrological balance of soils. Problems that may arise from these interventions relate to the reduction of organic substances, enrichment of calcium carbonate and soluble salts, impacting development and health of grapevines. Reduced water retention capacity can lead to increased water stress during dry season, decreased water permeability and circulation of oxygen in the soil, increased runoff volume, surface erosion and landslide risk, reduced biodiversity and limitation of biochemical processes (organic matter mineralization, bioavailability of nutrients, etc.). Soil degradations can lead to the loss of soil functionality even after the planting as a result of accelerated erosion, compaction by agricultural vehicles, excessive loss of organic matter and nutrients, and the accumulation of heavy metals such as copper. In both conventional and organic vineyards, it is quite common to have areas with reduced soil functionality that have negative impact on vine health and grape production and quality. In the framework of the Core organic RESOLVE project, a study was conducted in organic vineyards showing areas with reduced and good soil functionality. Degraded soils resulted in significantly lower amounts of grapes. The chlorophyll index (SPAD) of the grapevine during veraison was significantly lower in areas of degraded soils compared with the situation in areas of the same vineyard with non-degraded soils. In general, causes of soil malfunctioning were related to a lower fertility, including reduced organic carbon, total nitrogen and cation exchange capacity, higher concentrations of carbonates, and

  14. Influence of long-term fertilization on soil enzyme activities

    Directory of Open Access Journals (Sweden)

    Alina Dora SAMUEL

    2009-05-01

    Full Text Available Soil enzyme activities (actual and potential dehydrogenase, catalase, acid and alkaline phosphatase were determined in the 0–10, 10–20, and 20–30 cm layers of a brown luvic soil submitted to a complex fertilization experiment with different types of green manure. It was found that each activity decreased with increasing sampling depth. It should be emphasized that greenmanuring of maize led to a significant increase in each of the five enzymatic activities determined. The enzymatic indicators of soil quality calculated from the values of enzymatic activities showed the order: lupinus + rape + oat > lupinus > vetch + oat + ryegrass > lupinus + oat + vetch > unfertilized plot. This order means that by determination of enzymatic activities valuable information can be obtained regarding fertility status of soils. There were significant correlations of soil enzyme activities with chemical properties.

  15. Phosphorus Dynamics in Long-Term Flooded, Drained, and Reflooded Soils

    Directory of Open Access Journals (Sweden)

    Juan Tian

    2017-07-01

    Full Text Available In flooded areas, soils are often exposed to standing water and subsequent drainage, thus over fertilization can release excess phosphorus (P into surface water and groundwater. To investigate P release and transformation processes in flooded alkaline soils, wheat-growing soil and vegetable-growing soil were selected. We flooded-drained-reflooded two soils for 35 d, then drained the soils, and 10 d later reflooded the soils for 17 d. Dissolved reactive phosphorus (DRP, soil inorganic P fractions, Olsen P, pH, and Eh in floodwater and pore water were analyzed. The wheat-growing soil had significantly higher floodwater DRP concentrations than vegetable-growing soil, and floodwater DRP in both soils decreased with the number of flooding days. During the reflooding period, DRP in overlying floodwater from both soils was less than 0.87 mg/L, which was 3–25 times less than that during the flooding period. Regardless of flooding or reflooding, pore water DRP decreased with flooding days. The highest concentration of pore water DRP observed at a 5-cm depth. Under the effect of fertilizing and flooding, the risk of vertical P movement in 10–50 cm was enhanced. P diffusion occurred from the top to the bottom of the soils. After flooding, Al-P increased in both soils, and Fe-P, O-P, Ca2-P decreased, while Fe-P, Al-P, and O-P increased after reflooding, When Olsen P in the vegetable-growing soil exceeded 180.7 mg/kg and Olsen P in the wheat-growing soil exceeded 40.8 mg/kg, the concentration of DRP in pore water increased significantly. Our results showed that changes in floodwater and pore water DRP concentrations, soil inorganic P fractions, and Olsen P are significantly affected by fertilizing and flooding; therefore, careful fertilizer management should be employed on flooded soils to avoid excess P loss.

  16. Apparent soil electrical conductivity in two different soil types

    Directory of Open Access Journals (Sweden)

    Wilker Nunes Medeiros

    Full Text Available ABSTRACT Mapping the apparent soil electrical conductivity (ECa has become important for the characterization of the soil variability in precision agriculture systems. Could the ECa be used to locate the soil sampling points for mapping the chemical and physical soil attributes? The objective of this work was to examine the relations between ECa and soil attributes in two fields presenting different soil textures. In each field, 50 sampling points were chosen using a path that presented a high variability of ECa obtained from a preliminary ECa map. At each sampling point, the ECa was measured in soil depths of 0-20, 0-40 and 0-60 cm. In addition, at each point, soil samples were collected for the determination of physical and chemical attributes in the laboratory. The ECa data obtained for different soil depths was very similar. A large number of significant correlations between ECa and the soil attributes were found. In the sandy clay loam texture field there was no correlation between ECa and organic matter or between ECa and soil clay and sand content. However, a significant positive correlation was shown for the remaining phosphorus. In the sandy loam texture field the ECa had a significant positive correlation with clay content and a significant negative correlation with sand content. The results suggest that the mapping of apparent soil electrical conductivity does not replace traditional soil sampling, however, it can be used as information to delimit regions in a field that have similar soil attributes.

  17. Molecular and Microbial Mechanisms Increasing Soil C Storage Under Future Rates of Anthropogenic N Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zak, Donald R. [Univ. of Michigan, Ann Arbor, MI (United States)

    2017-11-17

    A growing body of evidence reveals that anthropogenic N deposition can reduce the microbial decay of plant detritus and increase soil C storage across a wide range of terrestrial ecosystems. This aspect of global change has the potential to constrain the accumulation of anthropogenic CO2 in the Earth’s atmosphere, and hence slow the pace of climate warming. The molecular and microbial mechanisms underlying this biogeochemical response are not understood, and they are not a component of any coupled climate-biogeochemical model estimating ecosystem C storage, and hence, the future climate of an N-enriched Earth. Here, we report the use of genomic-enabled approaches to identify the molecular underpinnings of the microbial mechanisms leading to greater soil C storage in response to anthropogenic N deposition, thereby enabling us to better anticipate changes in soil C storage.

  18. Carbon Sequestration in Arable Soils is Likely to Increase Nitrous Oxide Emissions, Offsetting Reductions in Climate Radiative Forcing

    International Nuclear Information System (INIS)

    Li, Changsheng Li; Frolking, S.; Butterbach-Bahl, K.

    2005-01-01

    Strategies for mitigating the increasing concentration of carbon dioxide (CO2) in the atmosphere include sequestering carbon (C) in soils and vegetation of terrestrial ecosystems. Carbon and nitrogen (N) move through terrestrial ecosystems in coupled biogeochemical cycles, and increasing C stocks in soils and vegetation will have an impact on the N cycle. We conducted simulations with a biogeochemical model to evaluate the impact of different cropland management strategies on the coupled cycles of C and N, with special emphasis on C-sequestration and emission of the greenhouse gases methane (CH4) and nitrous oxide (N2O). Reduced tillage, enhanced crop residue incorporation, and farmyard manure application each increased soil C-sequestration, increased N2O emissions, and had little effect on CH4 uptake. Over 20 years, increases in N2O emissions, which were converted into CO2-equivalent emissions with 100-year global warming potential multipliers, offset 75-310% of the carbon sequestered, depending on the scenario. Quantification of these types of biogeochemical interactions must be incorporated into assessment frameworks and trading mechanisms to accurately evaluate the value of agricultural systems in strategies for climate protection

  19. Effects on water, soil and vegetation of an increasing atmospheric supply of sulfur: a survey on ecological bases

    Energy Technology Data Exchange (ETDEWEB)

    Malmer, N; Nilsson, F M.I.

    1974-01-01

    In this paper a critical survey is given of the research work carried out on the ecological effects of the increasing rate of sulfur deposition, especially with reference to Swedish conditions. It also contains information about soil types and soil conditions of importance for the understanding of the problems. In several lakes and rivers this increased supply of sulfur (mainly as SO/sub 4//sup 2 -/) has brought about a considerable decrease in pH. In most lakes and rivers of the oligotrophic type the concentration of bicarbonate ion (the main buffer of pH changes) was already low, and it has now been reduced to the extent that a further increase in the deposition of sulfate will immediately result in marked and much more widespread acidification. The increase in the supply of sulfur which has already occurred will influence the conditions of the soil in several ways. A distinct decrease in forest productivity is to be expected. Due to the short time that has passed since the supply of sulfur started to increase it is, however, doubtful whether such a decrease is yet measurable with the measurement methods commonly used in forest taxation. 88 references.

  20. 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.

  1. Soil microbial communities and glyphosate decay in soils with different herbicide application history.

    Science.gov (United States)

    Guijarro, Keren Hernández; Aparicio, Virginia; De Gerónimo, Eduardo; Castellote, Martín; Figuerola, Eva L; Costa, José Luis; Erijman, Leonardo

    2018-04-11

    This study evaluates the glyphosate dissipation under field conditions in three types of soil, and aims to determine the importance of the following factors in the environmental persistence of herbicide: i) soil bacterial communities, ii) soil physicochemical properties, iii) previous exposure to the herbicide. A soil without previous record of GP application (P0) and two agricultural soils, with 5 and >10years of GP exposure (A5 and A10) were subjected to the application of glyphosate at doses of 3mg·kg -1 . The concentration of GP and AMPA was determined over time and the dynamics of soil bacterial communities was evaluated using 16S ARN ribosomal gene amplicon-sequencing. The GP exposure history affected the rate but not the extent of GP biodegradation. The herbicide was degraded rapidly, but P0 soil showed a dissipation rate significantly lower than soils with agricultural history. In P0 soil, a significant increase in the relative abundance of Bacteroidetes was observed in response to herbicide application. More generally, all soils displayed shifts in bacterial community structure, which nevertheless could not be clearly associated to glyphosate dissipation, suggesting the presence of redundant bacteria populations of potential degraders. Yet the application of the herbicide prompted a partial disruption of the bacterial association network of unexposed soil. On the other hand, higher values of linear (Kd) and nonlinear (Kf) sorption coefficient in P0 point to the relevance of cation exchange capacity (CEC), clay and organic matter to the capacity of soil to adsorb the herbicide, suggesting that bioavailability was a key factor for the persistence of GP and AMPA. These results contribute to understand the relationship between bacterial taxa exposed to the herbicide, and the importance of soil properties as predictors of the possible rate of degradation and persistence of glyphosate in soil. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Experimental Study of Factors Affecting Soil Erodibility

    Science.gov (United States)

    Larionov, G. A.; Bushueva, O. G.; Gorobets, A. V.; Dobrovolskaya, N. G.; Kiryukhina, Z. P.; Krasnov, S. F.; Litvin, L. F.; Maksimova, I. A.; Sudnitsyn, I. I.

    2018-03-01

    The effect of different factors and preparation conditions of monofraction samples from the arable horizon of leached chernozem on soil erodibility and its relationship with soil tensile strength (STS) has been studied. The exposure of samples at 38°C reduces their erodibility by two orders of magnitude. The drying of samples, on the contrary, increases their erodibility. It has been shown that erodibility decreases during the experiment. It has been found that the inoculation of soil with yeast cultures ( Naganishia albida, Lipomyces tetrasporus) reliably increases the STS value in 1.5-1.9 times. The sterile soil is eroded more intensively than the unsterile soil: at 4.9 and 0.3 g/(m2 s), respectively. The drying of soil followed by wetting to the initial water content (30%) has no significant effect on the STS value in almost all experimental treatments.

  3. [Effects of brackish water irrigation on soil enzyme activity, soil CO2 flux and organic matter decomposition].

    Science.gov (United States)

    Zhang, Qian-qian; Wang, Fei; Liu, Tao; Chu, Gui-xin

    2015-09-01

    Brackish water irrigation utilization is an important way to alleviate water resource shortage in arid region. A field-plot experiment was set up to study the impact of the salinity level (0.31, 3.0 or 5.0 g · L(-1) NaCl) of irrigated water on activities of soil catalase, invertase, β-glucosidase, cellulase and polyphenoloxidase in drip irrigation condition, and the responses of soil CO2 flux and organic matter decomposition were also determined by soil carbon dioxide flux instrument (LI-8100) and nylon net bag method. The results showed that in contrast with fresh water irrigation treatment (CK), the activities of invertase, β-glucosidase and cellulase in the brackish water (3.0 g · L(-1)) irrigation treatment declined by 31.7%-32.4%, 29.7%-31.6%, 20.8%-24.3%, respectively, while soil polyphenoloxidase activity was obviously enhanced with increasing the salinity level of irrigated water. Compared to CK, polyphenoloxidase activity increased by 2.4% and 20.5%, respectively, in the brackish water and saline water irrigation treatments. Both soil microbial biomass carbon and microbial quotient decreased with increasing the salinity level, whereas, microbial metabolic quotient showed an increasing tendency with increasing the salinity level. Soil CO2 fluxes in the different treatments were in the order of CK (0.31 g · L(-1)) > brackish water irrigation (3.0 g · L(-1)) ≥ saline water irrigation (5.0 g · L(-1)). Moreover, CO2 flux from plastic film mulched soil was always much higher than that from no plastic film mulched soil, regardless the salinity of irrigated water. Compared with CK, soil CO2 fluxes in the saline water and brackish water treatments decreased by 29.8% and 28.2% respectively in the boll opening period. The decomposition of either cotton straw or alfalfa straw in the different treatments was in the sequence of CK (0.31 g · L(-1)) > brackish water irrigation (3.0 g · L(-1)) > saline water treatment (5.0 g · L(-1)). The organic matter

  4. Colloid mobilization and heavy metal transport in the sampling of soil solution from Duckum soil in South Korea.

    Science.gov (United States)

    Lee, Seyong; Ko, Il-Won; Yoon, In-Ho; Kim, Dong-Wook; Kim, Kyoung-Woong

    2018-03-24

    Colloid mobilization is a significant process governing colloid-associated transport of heavy metals in subsurface environments. It has been studied for the last three decades to understand this process. However, colloid mobilization and heavy metal transport in soil solutions have rarely been studied using soils in South Korea. We investigated the colloid mobilization in a variety of flow rates during sampling soil solutions in sand columns. The colloid concentrations were increased at low flow rates and in saturated regimes. Colloid concentrations increased 1000-fold higher at pH 9.2 than at pH 7.3 in the absence of 10 mM NaCl solution. In addition, those were fourfold higher in the absence than in the presence of the NaCl solution at pH 9.2. It was suggested that the mobility of colloids should be enhanced in porous media under the basic conditions and the low ionic strength. In real field soils, the concentrations of As, Cr, and Pb in soil solutions increased with the increase in colloid concentrations at initial momentarily changed soil water pressure, whereas the concentrations of Cd, Cu, Fe, Ni, Al, and Co lagged behind the colloid release. Therefore, physicochemical changes and heavy metal characteristics have important implications for colloid-facilitated transport during sampling soil solutions.

  5. Aided Phytostabilization of Copper Contaminated Soils with L. Perenne and Mineral Sorbents as Soil Amendments

    Science.gov (United States)

    Radziemska, Maja

    2017-09-01

    The present study was designed to assess phytostabilization strategies for the treatment of soil co-contaminated by increasing levels of copper with the application mineral amendments (chalcedonite, zeolite, dolomite). From the results it will be possible to further elucidate the benefits or potential risks derived from the application of different types of mineral amendments in the remediation of a copper contaminated soil. A glasshouse pot experiment was designed to evaluate the potential use of different amendments as immobilizing agents in the aided phytostabilization of Cu-contaminated soil using ryegrass (Lolium perenne L.). The content of trace elements in plants and total in soil, were determined using the method of spectrophotometry. All of the investigated element contents in the tested parts of L. perenne were significantly different in the case of applying mineral amendments to the soil, as well as increasing concentrations of copper. The greatest average above-ground biomass was observed for soil amended with chalcedonite. In this experiment, all analyzed metals accumulated predominantly in the roots of the tested plant. In general, applying mineral amendments to soil contributed to decreased levels of copper concentrations.

  6. Improvement of nitrogen utilization and soil properties by addition of a mineral soil conditioner: mechanism and performance.

    Science.gov (United States)

    Yan, Xiaodan; Shi, Lin; Cai, Rumeng

    2018-01-01

    A mineral soil conditioner (MSC) composed of activated potash feldspar, gypsum, and calcium carbonate and containing an amount of available mineral nutrients, is shown to be effective for plant growth and acidic soil amelioration. In this study, a field test was conducted over four rice seasons by examining treatment with control check (CK), MSC, biological active carbon, and lime to investigate the nitrogen-use efficiency and mechanism of soil characteristic variations due to the desilicification and allitization of soil as well as the unrestrained use of nitrogen (N) fertilizer in recent years. Influences of MSC on the xylem sap intensity and mean rice yields were evaluated, and the soil type was also analyzed using the FactSage 6.1 Reaction, phase diagram, and Equilib modules. The results of the field trial showed that MSC application increased the xylem sap intensity and nitrogen export intensity by 37.33-39.85% and 31.40-51.20%, respectively. A significant increase (5.63-15.48%) in mean grain yields was achieved with MSC application over that with biological active carbon and lime application. The effects of MSC had a tendency to increase with time in the field experiment results, and grain yields increased after the initial application. The new formation of clay minerals exhibits a significant influence on [Formula: see text] fixation, especially for 2:1 phyllosilicates with illite, owing to the interlayers of the clay minerals. Our preliminary results showed that kaolinite, the main 1:1 phyllosilicate clay mineral in ferralsol, transformed to illite at room temperature as a consequence of the presence of H 4 SiO 4 and available K + supplied by MSC. This indicated that improving the soil quality combined with reducing N losses from soils is an efficient way to control non-point source pollution from agriculture without the risk of decreased in grain yield.

  7. Effect of soil solarization on soil-borne pathogens

    International Nuclear Information System (INIS)

    Sobh, Hana

    1995-01-01

    Author.Soil solarization was conducted at three locations on the Lebanese coast. Maximum soil temperatures recorded were 53 and 48 celsius degrees at Jiyeh, 48.9, 46 and 43 celsius degrees at Naameh and 48, 45 and 43.5 celsius degrees at Khaldeh at 5, 15 and 25cm soil depths respectively. Mean soil temperatures recorded at 3pm were at Jiyeh 51.6, 47 and 46 celsius degrees compared to Naameh 47, 45 and 41 celsius degrees and Khaldeh 44, 42 and 41 celsius degrees at 5, 15 and 25 cm respectively. The mean temperature in solarized soils were 7.3 to 15 celsius degrees higher than those of the nonsolarized soils indicating a sustained increase of soil temperature in the solarized soils. The effect of soil solarization on artificially introduced fungal pathogens in the soil at Khaldeh, resulted in complete destruction of sclerotia of Sclerotinia spp. at three depths studied. However, with respect to the two other pathogens tested, solarization resulted in reduction of the viability of microsclerotia of Verticillium spp. by 99-79% and of Fusarium oxysporum f. sp. melonis inoculum by 88-54% at 5 and 15 cm respectively, but only by 45% and 14% reduction at 25 cm. This level of control is significant when it is compared to the percentage of control where the level of reduction of inoculum viability did not exceed 10% at any soil depth. As there were contradicting reports in the literature on nematodes, two field trials in greenhouses were conducted to study the possibility of integrating 2 methods for management on nematodes. Soil solarization alone or in combination with biological control of nematodes using Arthrobotrys spp. and Dactyl ella brocophaga to control the root-knot nematodes on two crops, tomato at Naameh and cucumber at Jiyeh were compared to Methyl Bromide treatment. It was evident that, even on a very susceptible crop like cucumber, the integration of biological control and soil solarization gave a good level of control similar to methyl bromide. Neither root

  8. How grazing affects soil quality of soils formed in the glaciated northeastern United States.

    Science.gov (United States)

    Cox, Alissa H; Amador, José A

    2018-02-21

    Historically, much of the New England landscape was converted to pasture for grazing animals and harvesting hay. Both consumer demand for local sustainably produced food, and the number of small farms is increasing in RI, highlighting the importance of characterizing the effects livestock have on the quality of pasture soils. To assess how livestock affect pasture on Charlton and Canton soils series in RI, we examined soil quality in farms raising beef cattle (Bos taurus), sheep (Ovis aries), and horses (Equus ferus caballus), using hayed pastures as a control. We sampled three pastures per livestock type and three control hayed pastures in May, August, and October 2012. Hay fields and pastures grazed by sheep had statistically significant (P soil quality than pastures grazed by beef cattle or horses. This was driven by parameters including penetration resistance, bulk density, aggregate stability, and infiltration rate. Hayfields also showed higher soil quality measures than grazed pastures for organic matter content and active C. In addition, significant differences in nitrate and phosphate concentrations were observed among livestock types. Respiration and infiltration rates, pH, and ammonium concentrations, on the other hand, did not differ significantly among pasture types. When all soil quality indicators in this study were weighed equally, soil quality scores followed the order: hay > sheep > beef cattle > horses. The results of our study provide baseline data on the effect different types of livestock have on pasture soil quality in RI, which may be useful in making sound land use and agricultural management decisions.

  9. [Effects of management regime on soil respiration from agroecosystems].

    Science.gov (United States)

    Chen, Shu-tao; Zhu, Da-wei; Niu, Chuan-po; Zou, Jian-wen; Wang, Chao; Sun, Wen-juan

    2009-10-15

    In order to examine the effects of management regime, such as nitrogen application and plowing method, on soil respiration from farmland, the static opaque chamber-gas chromatograph method was used to measure soil CO2 fluxes in situ. The field measurement was carried out for 5 growing seasons, which were the 2002-2003 wheat, 2003 maize and soybean, 2003-2004 wheat, 2004 maize and 2004-2005 wheat seasons. Our results showed that soil respiration increased in fertilizer-applied treatments compared with no fertilizer treatment after 3 times of fertilizer application on 9 November 2002, 14 February and 26 March 2003. And the most obvious increase appeared following the third fertilizer application. No significant difference in soil respiration was found among several fertilizer application treatments. The effect of plowing depth on soil respiration was contingent on preceding cropping practice. Over the 2003-2004 wheat-growing seasons (its preceding cropping practice was rice paddy), mean soil respiration rates were not significant different (p > 0.05) between no plowing treatment and shallow plowing treatment. The shallow plowing treatment CT2 led to higher soil CO2 losses compared with no plowing treatment of NT2 in the 2004 maize-growing season, however, the significant higher (p soil respiration rates occurred with no plowing treatment of NT3 in the following 2004-2005 wheat-growing season. Intensive plowing (25 cm depth), compared with no plowing practice (NT4), increased soil respiration significantly during the 2004-2005 wheat-growing season. Regression analysis showed that the exponential function could be employed to fit the relationship between soil respiration and temperature. The exponential relationship yielded the Q10 values which were varied from 1.26 to 3.60, with a mean value of 2.08. To evaluate the effect of temperature on soil respiration, the CO2 emission fluxes were normalized for each treatment and each crop growing season. Plotting the

  10. Elevated CO2 benefits the soil microenvironment in the rhizosphere of Robinia pseudoacacia L. seedlings in Cd- and Pb-contaminated soils.

    Science.gov (United States)

    Huang, Shuping; Jia, Xia; Zhao, Yonghua; Bai, Bo; Chang, Yafei

    2017-02-01

    Soil contamination by heavy metals in combination with elevated atmospheric CO 2 has important effects on the rhizosphere microenvironment by influencing plant growth. Here, we investigated the response of the R. pseudoacacia rhizosphere microenvironment to elevated CO 2 in combination with cadmium (Cd)- and lead (Pb)-contamination. Organic compounds (total soluble sugars, soluble phenolic acids, free amino acids, and organic acids), microbial abundance and activity, and enzyme activity (urease, dehydrogenase, invertase, and β-glucosidase) in rhizosphere soils increased significantly (p soil microbial community in the rhizosphere. Heavy metals alone resulted in an increase in total soluble sugars, free amino acids, and organic acids, a decrease in phenolic acids, microbial populations and biomass, and enzyme activity, and a change in microbial community in rhizosphere soils. Elevated CO 2 led to an increase in organic compounds, microbial populations, biomass, and activity, and enzyme activity (except for l-asparaginase), and changes in microbial community under Cd, Pb, or Cd + Pb treatments relative to ambient CO 2 . In addition, elevated CO 2 significantly (p soils. Overall, elevated CO 2 benefited the rhizosphere microenvironment of R. pseudoacacia seedlings under heavy metal stress, which suggests that increased atmospheric CO 2 concentrations could have positive effects on soil fertility and rhizosphere microenvironment under heavy metals. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Potassium adsorption behaviour of three Malaysian rice soils

    International Nuclear Information System (INIS)

    Choudhury, A.T.M.A.; Khanif, Y.M.

    2003-01-01

    Potassium (K) deficiency exists in different rice growing areas of Malaysia. A study on K adsorption was carried out in three Malaysian rice soils (Guar, Hutan and Kangar series) using six levels of K (0.00,28.77, 33.57, 38.37, 43.16 and 47.96 mmol kg/sup -1/). The data on K adsorption were fitted into Langmuir, Freundlich, and Temkin adsorption equations. Adsorption data were also correlated with pH, cation exchange capacity and organic matter content of the soils. Potassium adsorption increased linearly with increasing level of added K in all the three soils. The rate of increase was the highest in Guar series followed by Kangar and Hutan series, respectively. Potassium adsorption in two soils (Hutan and Kangar) fitted into Langmuir equation while he adsorption data in Guar series did not fit into this equation. Adsorption data in none of the soils fitted well in Freundlich and Temkin adsorption equations. Correlation between K adsorption and pH was significant (r = 0.881,), whereas, correlation of K adsorption with either organic matter content or cation exchange capacity was non-significant. The results of this study indicated that K adsorption is mainly dependent on soil pH. In soils with higher adsorption capacity, more K fertilizer may be needed to get immediate crop response. (author)

  12. Mobile heavy metal fractions in soils

    International Nuclear Information System (INIS)

    Horak, O.; Kamel, A.A.; Ecker, S.; Benetka, E.; Rebler, R.; Lummerstorfer, E.; Kandeler, E.

    1994-01-01

    A long term outdoor experiment was conducted in plastic containers (50 litres) with three soils, contaminated by increasing concentrations of zinc, copper, nickel, cadmium and vanadium. The aim of the study was to investigate the influence of heavy metal contamination on soil microbial processes as well as the accumulation of heavy metals in plants. Spring barley, followed by winter endive were grown as experimental crops in a first vegetation period, while spring wheat was grown during the second year. The soil microbial activities, indicated by arylsulfatase, dehydrogenase, and substrate-induced respiration, decreased with increasing heavy metal contamination. Significant correlations were observed between the inhibition of soil microorganisms and the easily mobilizable heavy metal fractions of soils, extracted by a solution of 1 M ammoniumacetate at pH = 7. The heavy metal accumulation in vegetative and generative parts of the crop plants also showed a good agreement with mobilizable soil fractions. The results of the experiment indicate, that the extraction with ammoniumacetate can be used as a reference method for determination of tolerable heavy metal concentrations in soils. (authors)

  13. Amending a loamy sand with three compost types: impact on soil quality

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Cornelis, W.M.; Vermang, J.

    2011-01-01

    indicators of soil physical quality. Soil samples were taken from a field with annual compost applications of 30 m3/ha for 10 yr and various physico-chemical analyses were undertaken. Results show a significant increase in soil organic carbon (21%) with the VFYW and GW compost types. With SM, soil organic...... carbon increased by 16%. Increased soil macroporosity and water content at saturation with a corresponding decrease in bulk density were observed for all compost types. However, quantification of these improvements using existing soil physical quality indicators such as the ‘S-index’, soil air capacity...... are a viable disposal option for these composts, but new indices of quality are needed for the proper characterization of sandy soils....

  14. Beyond clay - using selective extractions to improve predictions of soil carbon content

    Science.gov (United States)

    Rasmussen, C.; Berhe, A. A.; Blankinship, J. C.; Crow, S. E.; Druhan, J. L.; Heckman, K. A.; Keiluweit, M.; Lawrence, C. R.; Marin-Spiotta, E.; Plante, A. F.; Schaedel, C.; Schimel, J.; Sierra, C. A.; Thompson, A.; Wagai, R.; Wieder, W. R.

    2016-12-01

    A central component of modern soil carbon (C) models is the use of clay content to scale the relative partitioning of decomposing plant material to respiration and mineral stabilized soil C. However, numerous pedon to plot scale studies indicate that other soil mineral parameters, such as Fe- or Al-oxyhydroxide content and specific surface area, may be more effective than clay alone for predicting soil C content and stabilization. Here we directly address the following question: Are there soil physicochemical parameters that represent mineral C association and soil C content that can replace or be used in conjunction with clay content as scalars in soil C models. We explored the relationship of soil C content to a number of soil physicochemical and physiographic parameters using the National Cooperative Soil Survey database that contains horizon level data for > 62,000 pedons spanning global ecoregions and geographic areas. The data indicated significant variation in the degree of correlation among soil C, clay and Fe-/Al-oxyhydroxides with increasing moisture variability. Specifically, dry, water-limited systems (PET/MAP > 1) presented strong positive correlations between clay and soil C, that decreased significantly to little or no correlation in wet, energy-limited systems (PET/MAP soil C to oxalate extractable Al+Fe increased significantly with increasing moisture availability. This pattern was particularly well expressed for subsurface B horizons. Multivariate analyses indicated similar patterns, with clear climate and ecosystem level variation in the degree of correlation among soil C and soil physicochemical properties. The results indicate a need to modify current soil C models to incorporate additional C partitioning parameters that better account for climate and ecoregion variability in C stabilization mechanisms.

  15. Membrane proteins involved in transport, vesicle traffic and Ca(2+) signaling increase in beetroots grown in saline soils.

    Science.gov (United States)

    Lino, Bárbara; Chagolla, Alicia; E González de la Vara, Luis

    2016-07-01

    By separating plasma membrane proteins according to their hydropathy from beetroots grown in saline soils, several proteins probably involved in salt tolerance were identified by mass spectrometry. Beetroots, as a salt-tolerant crop, have developed mechanisms to cope with stresses associated with saline soils. To observe which plasma membrane (PM) proteins were more abundant in beet roots grown in saline soils, beet root plants were irrigated with water or 0.2 M NaCl. PM-enriched membrane preparations were obtained from these plants, and their proteins were separated according to their hydropathy by serial phase partitioning with Triton X-114. Some proteins whose abundance increased visibly in membranes from salt-grown beetroots were identified by mass spectrometry. Among them, there was a V-type H(+)-ATPase (probably from contaminating vacuolar membranes), which increased with salt at all stages of beetroots' development. Proteins involved in solute transport (an H(+)-transporting PPase and annexins), vesicle traffic (clathrin and synaptotagmins), signal perception and transduction (protein kinases and phospholipases, mostly involved in calcium signaling) and metabolism, appeared to increase in salt-grown beetroot PM-enriched membranes. These results suggest that PM and vacuolar proteins involved in transport, metabolism and signal transduction increase in beet roots adapted to saline soils. In addition, these results show that serial phase partitioning with Triton X-114 is a useful method to separate membrane proteins for their identification by mass spectrometry.

  16. Lumbricus terrestris L. activity increases the availability of metals and their accumulation in maize and barley

    International Nuclear Information System (INIS)

    Ruiz, E.; Alonso-Azcarate, J.; Rodriguez, L.

    2011-01-01

    The effect of the earthworm Lumbricus terrestris L. on metal availability in two mining soils was assessed by means of chemical extraction methods and a pot experiment using crop plants. Results from single and sequential extractions showed that L. terrestris had a slight effect on metal fractionation in the studied soils: only metals bound to the soil organic matter were significantly increased in some cases. However, we found that L. terrestris significantly increased root, shoot and total Pb and Zn concentrations in maize and barley for the soil with the highest concentrations of total and available metals. Specifically, shoot Pb concentration was increased by a factor of 7.5 and 3.9 for maize and barley, respectively, while shoot Zn concentration was increased by a factor of 3.7 and 1.7 for maize and barley, respectively. Our results demonstrated that earthworm activity increases the bioavailability of metals in soils. - Research highlights: → Lumbricus terrestris L. activity increases the bioavailability of metals in soils. → Earthworm activity can significantly increase total, shoot and root metal concentrations for crop plants. → Both bioassays and chemical extraction methods are necessary for assessing the bioavailability of metals in contaminated soils. - Lumbricus terrestris L. activity increases the bioavailability of metals in soils and total, shoot and root metal concentrations for maize and barley.

  17. Lumbricus terrestris L. activity increases the availability of metals and their accumulation in maize and barley

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, E. [Department of Chemical Engineering, School of Civil Engineering, University of Castilla-La Mancha, Avenida Camilo Jose Cela, s/n, 13071 Ciudad Real (Spain); Alonso-Azcarate, J. [Department of Physical Chemistry, Faculty of Environmental Sciences, University of Castilla-La Mancha, Avenida Carlos III, s/n, 45071 Toledo (Spain); Rodriguez, L., E-mail: Luis.Rromero@uclm.es [Department of Chemical Engineering, School of Civil Engineering, University of Castilla-La Mancha, Avenida Camilo Jose Cela, s/n, 13071 Ciudad Real (Spain)

    2011-03-15

    The effect of the earthworm Lumbricus terrestris L. on metal availability in two mining soils was assessed by means of chemical extraction methods and a pot experiment using crop plants. Results from single and sequential extractions showed that L. terrestris had a slight effect on metal fractionation in the studied soils: only metals bound to the soil organic matter were significantly increased in some cases. However, we found that L. terrestris significantly increased root, shoot and total Pb and Zn concentrations in maize and barley for the soil with the highest concentrations of total and available metals. Specifically, shoot Pb concentration was increased by a factor of 7.5 and 3.9 for maize and barley, respectively, while shoot Zn concentration was increased by a factor of 3.7 and 1.7 for maize and barley, respectively. Our results demonstrated that earthworm activity increases the bioavailability of metals in soils. - Research highlights: > Lumbricus terrestris L. activity increases the bioavailability of metals in soils. > Earthworm activity can significantly increase total, shoot and root metal concentrations for crop plants. > Both bioassays and chemical extraction methods are necessary for assessing the bioavailability of metals in contaminated soils. - Lumbricus terrestris L. activity increases the bioavailability of metals in soils and total, shoot and root metal concentrations for maize and barley.

  18. The Influence of Soil Particle on Soil Condensation Water

    OpenAIRE

    Hou Xinwei; Chen Hao; Li Xiangquan; Cui Xiaomei; Liu Lingxia; Wang Zhenxing

    2013-01-01

    The experiment results showed that the indoor experiment formed from the volume of soil hygroscopic water increased gradually with decreasing size of soil particles. In the outdoor experiments, the results showed that the formed condensation water in medium sand was greater than it was in fine sand; the soil hot condensation water was mainly formed in the top layer of soil between 0-5 cm. We also found that covering the soil surface with stones can increase the volume of formed soil condensat...

  19. Carbon stabilization and microbial growth in acidic mine soils after addition of different amendments for soil reclamation

    Science.gov (United States)

    Zornoza, Raúl; Acosta, Jose; Ángeles Muñoz, María; Martínez-Martínez, Silvia; Faz, Ángel; Bååth, Erland

    2016-04-01

    The extreme soil conditions in metalliferous mine soils have a negative influence on soil biological activity and therefore on soil carbon estabilization. Therefore, amendments are used to increase organic carbon content and activate microbial communities. In order to elucidate some of the factors controlling soil organic carbon stabilization in reclaimed acidic mine soils and its interrelationship with microbial growth and community structure, we performed an incubation experiment with four amendments: pig slurry (PS), pig manure (PM) and biochar (BC), applied with and without marble waste (MW; CaCO3). Results showed that PM and BC (alone or together with MW) contributed to an important increment in recalcitrant organic C, C/N ratio and aggregate stability. Bacterial and fungal growths were highly dependent on pH and labile organic C. PS supported the highest microbial growth; applied alone it stimulated fungal growth, and applied with MW it stimulated bacterial growth. BC promoted the lowest microbial growth, especially for fungi, with no significant increase in fungal biomass. MW+BC increased bacterial growth up to values similar to PM and MW+PM, suggesting that part of the biochar was degraded, at least in short-term mainly by bacteria rather than fungi. PM, MW+PS and MW+PM supported the highest microbial biomass and a similar community structure, related with the presence of high organic C and high pH, with immobilization of metals and increased soil quality. BC contributed to improved soil structure, increased recalcitrant organic C, and decreased metal mobility, with low stimulation of microbial growth.

  20. The Effect of Vegetation on Soil Water Infiltration and Retention Capacity by Improving Soil Physiochemical Property in Semi-arid Grassland

    Science.gov (United States)

    A, Y.; Wang, G.

    2017-12-01

    Water shortage is the main limiting factor for semi-arid grassland development. However, the grassland are gradually degraded represented by species conversion, biomass decrease and ecosystem structure simplification under the influence of human activity. Soil water characteristics such as moisture, infiltration and conductivity are critical variables affecting the interactions between soil parameters and vegetation. In this study, Cover, Height, Shannon-Wiener diversity index, Pielou evenness index and Richness index are served as indexes of vegetation productivity and community structure. And saturated hydraulic conductivity (Ks) and soil moisture content are served as indexes of soil water characters. The interaction between vegetation and soil water is investigated through other soil parameters, such as soil organic matter content at different vertical depths and in different degradation area (e.g., initial, transition and degraded plots). The results show that Ks significantly controlled by soil texture other than soil organic matter content. So the influence of vegetation on Ks through increasing soil organic content (SOM) might be slight. However, soil moisture content (SMC) appeared significantly positive relationship with SOM and silt content and negative relationship with sand content at all depth, significantly. This indicated that capacity of soil water storage was influenced both by soil texture and organic matter. In addition, the highest correlation coefficient of SMC was with SOM at the sub-surficial soil layer (20 40 cm). At the depth of 20 40 cm, the soil water content was relatively steady which slightly influenced by precipitation and evaporation. But it significantly influenced by soil organic matter content which related to vegetation. The correlation coefficient between SOM and SMC at topsoil layer (0 20 cm) was lowest (R2=0.36, pwater content not only by soil organic matter content but also the other influential factors, such as the root

  1. Microbial biomass, microbial diversity, soil carbon storage, and stability after incubation of soil from grass-clover pastures of different age

    DEFF Research Database (Denmark)

    Müller-Stöver, Dorette Sophie; Hauggaard-Nielsen, Henrik; Eriksen, Jørgen

    2012-01-01

    A laboratory incubation study with clover grass pasture soils of seven different ages (0, 1, 2, 3, 4, 5, and 16 production years) was carried out to determine initial soil carbon (C) and nitrogen (N) stocks and potentials for greenhouse gas emissions (N2O and CO2). Compared with the soil from...... the recently established pasture, an increase of total soil C and N was observed along with pasture age. Greenhouse gas emissions were low and not significantly different among the soils from younger pastures (0-5 years), but especially N2O emissions increased markedly in the soil from 16-year-old grass......-clover. Low emissions might mainly be due to an early C limitation occurring in the soils from younger pastures, which was also corroborated by decreasing levels of cold water-extractable C and early shifts within the microbial community. However, higher emissions from the old pasture soil were offset by its...

  2. Dust emission parameterization scheme over the MENA region: Sensitivity analysis to soil moisture and soil texture

    Science.gov (United States)

    Gherboudj, Imen; Beegum, S. Naseema; Marticorena, Beatrice; Ghedira, Hosni

    2015-10-01

    The mineral dust emissions from arid/semiarid soils were simulated over the MENA (Middle East and North Africa) region using the dust parameterization scheme proposed by Alfaro and Gomes (2001), to quantify the effect of the soil moisture and clay fraction in the emissions. For this purpose, an extensive data set of Soil Moisture and Ocean Salinity soil moisture, European Centre for Medium-Range Weather Forecasting wind speed at 10 m height, Food Agricultural Organization soil texture maps, MODIS (Moderate Resolution Imaging Spectroradiometer) Normalized Difference Vegetation Index, and erodibility of the soil surface were collected for the a period of 3 years, from 2010 to 2013. Though the considered data sets have different temporal and spatial resolution, efforts have been made to make them consistent in time and space. At first, the simulated sandblasting flux over the region were validated qualitatively using MODIS Deep Blue aerosol optical depth and EUMETSAT MSG (Meteosat Seciond Generation) dust product from SEVIRI (Meteosat Spinning Enhanced Visible and Infrared Imager) and quantitatively based on the available ground-based measurements of near-surface particulate mass concentrations (PM10) collected over four stations in the MENA region. Sensitivity analyses were performed to investigate the effect of soil moisture and clay fraction on the emissions flux. The results showed that soil moisture and soil texture have significant roles in the dust emissions over the MENA region, particularly over the Arabian Peninsula. An inversely proportional dependency is observed between the soil moisture and the sandblasting flux, where a steep reduction in flux is observed at low friction velocity and a gradual reduction is observed at high friction velocity. Conversely, a directly proportional dependency is observed between the soil clay fraction and the sandblasting flux where a steep increase in flux is observed at low friction velocity and a gradual increase is

  3. [Effect of different organic fertilizers on bioavailability of soil Cd and Zn].

    Science.gov (United States)

    Xie, Yun-he; Ji, Xiong-hui; Wu, Jia-mei; Huang, Juan; Guan, Di; Zhu, Jian

    2015-03-01

    The active effect of soil Cd and Zn and their interaction was studied in typical paddy field in south China by monitoring the contents of Cd and Zn in soil and rice in rice fields applied with pig manure, chicken manure or rice straw for 4 years continuously. The results showed that applying pig manure, chicken manure or rice straw had no significant impact on the soil total Cd content, soil available Cd content and soil Cd activity, but tended to increase the soil total Cd content and increased the soil total Zn content, soil available Zn content and Zn activity significantly. Applications of pig manure, chicken manure and rice straw all reduced the Cd content of brown rice, in order of pig manure > chicken manure > rice straw. The Cd contents of brown rice, stem and leaf in the treatment applied with pig manure were lower than in the control by 37.5%, 44.0% and 36.4%, respectively; the Cd contents of brown rice, stem and leaf in the treatment applied with chicken manure were lower than in the control by 22.5%, 33.8%, and 22.7%, respectively; the Cd content of brown rice in the treatment applied with rice straw was lower than in the control by 7.5% but its contents in stem and leaf increased by 8.2% and 22.7% , respectively. The reduction in the brown rice Cd content was mainly due to the reduction of Cd enrichment from soil to brown rice after application of pig or chicken manure, but mainly due to the reduction of Cd transportation from stem to brown rice after straw application. Applications of pig manure, chicken manure and rice straw increased Zn contents in rice stem by 53.4%, 53.4% and 13.9%, respectively, but all had no significant effect on brown rice and leaf' s Zn contents. Zn and Cd had the significant antagonistic effects in the soil and rice stem. The increase of Zn content in soil and rice stem inhibited the adsorption and accumulation of Cd in the brown rice, stem and leaf significantly, and with the increase of the proportion of Zn/Cd, the

  4. Effect of Water Quality and Temperature on the Efficiency of Two Kinds of Hydrophilic Polymers in Soil.

    Science.gov (United States)

    Dehkordi, Davoud Khodadadi

    2018-06-01

      In this study, evaluation of two-superabsorbent effects, Super-AB-A-300 and Super-AB-A-200 in a sandy soil on the water retention capability and saturated hydraulic conductivity (Ks) at different water quality and soil temperature were done. The Super-AB-A-200 was less effective in water uptake than Super-AB-A-300. The efficiency of these polymers in water retention was negatively influenced by the water quality and temperature. The efficiency of these polymer treatments in water uptake reduced significantly (P < 0.05) with increasing soil temperature. In the control soil, the Ks stayed nearly constant with increasing soil temperature. As compared to the untreated control, the treated soil demonstrated a significant (P < 0.05) linear increase of Ks with increasing soil temperature. In the control soil, the water holding properties curve did not change with increasing soil temperature.

  5. Organic matter and salinity modify cadmium soil (phyto)availability.

    Science.gov (United States)

    Filipović, Lana; Romić, Marija; Romić, Davor; Filipović, Vilim; Ondrašek, Gabrijel

    2018-01-01

    Although Cd availability depends on its total concentration in soil, it is ultimately defined by the processes which control its mobility, transformations and soil solution speciation. Cd mobility between different soil fractions can be significantly affected by certain pedovariables such as soil organic matter (SOM; over formation of metal-organic complexes) and/or soil salinity (over formation of metal-inorganic complexes). Phytoavailable Cd fraction may be described as the proportion of the available Cd in soil which is actually accessible by roots and available for plant uptake. Therefore, in a greenhouse pot experiment Cd availability was observed in the rhizosphere of faba bean exposed to different levels of SOM, NaCl salinity (50 and 100mM) and Cd contamination (5 and 10mgkg -1 ). Cd availability in soil does not linearly follow its total concentration. Still, increasing soil Cd concentration may lead to increased Cd phytoavailability if the proportion of Cd 2+ pool in soil solution is enhanced. Reduced Cd (phyto)availability by raised SOM was found, along with increased proportion of Cd-DOC complexes in soil solution. Data suggest decreased Cd soil (phyto)availability with the application of salts. NaCl salinity affected Cd speciation in soil solution by promoting the formation of CdCl n 2-n complexes. Results possibly suggest that increased Cd mobility in soil does not result in its increased availability if soil adsorption capacity for Cd has not been exceeded. Accordingly, chloro-complex possibly operated just as a Cd carrier between different soil fractions and resulted only in transfer between solid phases and not in increased (phyto)availability. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. [Effects of diurnal warming on soil N2O emission in soybean field].

    Science.gov (United States)

    Hu, Zheng-Hua; Zhou, Ying-Ping; Cui, Hai-Ling; Chen, Shu-Tao; Xiao, Qi-Tao; Liu, Yan

    2013-08-01

    To investigate the impact of experimental warming on N2O emission from soil of soybean field, outdoor experiments with simulating diurnal warming were conducted, and static dark chamber-gas chromatograph method was used to measure N2O emission fluxes. Results indicated that: the diurnal warming did not change the seasonal pattern of N2O emissions from soil. In the whole growing season, comparing to the control treatment (CK), the warming treatment (T) significantly enhanced the N2O flux and the cumulative amount of N2O by 17.31% (P = 0.019), and 20.27% (P = 0.005), respectively. The significant correlations were found between soil N2O emission and soil temperature, moisture. The temperature sensitivity values of soil N2O emission under CK and T treatments were 3.75 and 4.10, respectively. In whole growing stage, T treatment significantly increased the crop aboveground and total biomass, the nitrate reductase activity, and total nitrogen in leaves, while significantly decreased NO3(-) -N content in leaves. T treatment significantly increased soil NO3(-) -N content, but had no significant effect on soil organic carbon and total nitrogen contents. The results of this study suggested that diurnal warming enhanced N2O emission from soil in soybean field.

  7. Stable and radioactive carbon in Indian soils: implications to soil carbon dynamics

    International Nuclear Information System (INIS)

    Laskar, A.H.; Yadava, M.G.; Ramesh, R.

    2011-01-01

    Radiocarbon is a very useful tool to study soil carbon dynamic. The mean residence time of SOC in Indian soils is about a century at the top 0-15 cm, increases linearly to reach values ranging from 2000 to 4000 yrs at a depth of 100 cm. It mainly depends on the clay content indicating that the clay is the main governing factor for SOC stabilization. Stable carbon and oxygen isotopes in soil carbonates and SOC are good proxies for paleoclimate and paleovegetation reconstruction. The present day sub-humid climate in the lower Narmada valley has been established prior to ∼ 3 ka. Two comparatively arid phases around 2.1 and 1.3 ka are recorded by oxygen isotopes of soil carbonates; consistent with other proxy records showing its regional significance

  8. Effect of Exogenous Phytase Addition on Soil Phosphatase Activities: a Fluorescence Spectroscopy Study.

    Science.gov (United States)

    Yang, Xiao-zhu; Chen, Zhen-hua; Zhang, Yu-lan; Chen, Li-jun

    2015-05-01

    The utilization of organic phosphorus (P) has directly or indirectly improved after exogenous phytase was added to soil. However, the mechanism by which exogenous phytase affected the soil phosphatases (phosphomonoesterase and phosphodiesterase) activities was not clear. The present work was aimed to study red soil, brown soil and cinnamon soil phosphomonoesterase (acid and alkaline) (AcP and AlP) and phosphodiesterase (PD) activities responding to the addition of exogenous phytase (1 g phytase/50 g air dry soil sample) based on the measurements performed via a fluorescence detection method combined with 96 microplates using a TECAN Infinite 200 Multi-Mode Microplate Reader. The results indicated that the acid phosphomonoesterase activity was significantly enhanced in red soil (p≤0. 01), while it was significantly reduced in cinnamon soil; alkaline phosphomonoesterase activity was significantly enhanced in cinnamon soil (p≤ 0. 01), while it was significantly reduced in red soil; phosphodiesterase activity was increased in three soils but it was significantly increased in brown soil (p≤0. 01) after the addition of exogenous phytase. The activities still remained strong after eight days in different soils, which indicated that exogenous phytase addition could be enhance soil phosphatases activities effectively. This effect was not only related to soil properties, such as pH and phosphorus forms, but might also be related to the excreted enzyme amount of the stimulating microorganism. Using fluorescence spectroscopy to study exogenous phytase addition influence on soil phosphatase activities was the first time at home and abroad. Compared with the conventional spectrophotometric method, the fluorescence microplate method is an accurate, fast and simple to use method to determine the relationships among the soil phosphatases activities.

  9. [Effects of global change on soil fauna diversity: A review].

    Science.gov (United States)

    Wu, Ting-Juan

    2013-02-01

    Terrestrial ecosystem consists of aboveground and belowground components, whose interaction affects the ecosystem processes and functions. Soil fauna plays an important role in biogeochemical cycles. With the recognizing of the significance of soil fauna in ecosystem processes, increasing evidences demonstrated that global change has profound effects on soil faunima diversity. The alternation of land use type, the increasing temperature, and the changes in precipitation pattern can directly affect soil fauna diversity, while the increase of atmospheric CO2 concentration and nitrogen deposition can indirectly affect the soil fauna diversity by altering plant community composition, diversity, and nutrient contents. The interactions of different environmental factors can co-affect the soil fauna diversity. To understand the effects of different driving factors on soil fauna diversity under the background of climate change would facilitate us better predicting how the soil fauna diversity and related ecological processes changed in the future.

  10. Increasing microbial diversity and nitrogen cycling potential of burnt forest soil in Spain through post-fire management

    Science.gov (United States)

    Pereg, Lily; Mataix-Solera, Jorge; McMillan, Mary; García-Orenes, Fuensanta

    2016-04-01

    Microbial diversity and function in soils are increasingly assessed by the application of molecular methods such as sequencing and PCR technology. We applied these techniques to study microbial recovery in post-fire forest soils. The recovery of forest ecosystems following severe fire is influenced by post-fire management. The removal of burnt tree stumps (salvage logging) is a common practice in Spain following fire. In some cases, the use of heavy machinery in addition to the vulnerability of soils to erosion and degradation make this management potentially damaging to soil, and therefore to the ecosystem. We hypothesized that tree removal slows down the recovery of soil biological communities including microbial and plant communities and contributes to soil degradation in the burnt affected area. The study area is located in "Sierra de Mariola Natural Park" in Alcoi, Alicante (E Spain). A big forest fire (>500 has) occurred in July 2012. The forest is composed mainly of Pinus halepensis trees with an understory of typical Mediterranean shrubs species such as Quercus coccifera, Rosmarinus officinalis, Thymus vulgaris, Brachypodium retusum, etc. Soil is classified as a Typic Xerorthent (Soil Survey Staff, 2014) developed over marls. In February 2013, salvage logging (SL) treatment, with a complete extraction of the burned wood using heavy machinery, was applied to a part of the affected forest. Plots for monitoring the effects of SL were installed in this area and in a similar nearby control (C) area, where no SL treatment was done. The recovery of soil bacterial and fungal communities post-fire with and without tree removal was analysed by using Next-Generation sequencing and the abundance of functional genes, related to nitrogen cycling, in the soil was estimated using quantitative PCR (qPCR). We will present the methods used and the results of our study in this PICO presentation.

  11. Plant species influence on soil C after afforestation of Mediterranean degraded soils

    Science.gov (United States)

    Dominguez, Maria T.; García-Vargas, Carlos; Madejón, Engracia; Marañón, Teodoro

    2015-04-01

    Increasing C sequestration in terrestrial ecosystems is one of the main current environmental challenges to mitigate climate change. Afforestation of degraded and contaminated lands is one of the key strategies to achieve an increase in C sequestration in ecosystems. Plant species differ in their mechanisms of C-fixation, C allocation into different plant organs, and interaction with soil microorganisms, all these factors influencing the dynamics of soil C following the afforestation of degraded soils. In this work we examine the influence of different woody plant species on soil C dynamics in degraded and afforested Mediterranean soils. The soils were former agricultural lands that were polluted by a mining accident and later afforested with different native plant species. We analysed the effect of four of these species (Olea europaea var. sylvestris Brot., Populus alba L., Pistacia lentiscus L. and Retama sphaerocarpa (L.) Boiss.) on different soil C fractions, soil nutrient availability, microbial activity (soil enzyme activities) and soil CO2 fluxes 15 years after the establishment of the plantations. Results suggest that the influence of the planted trees and shrubs is still limited, being more pronounced in the more acidic and nutrient-poor soils. Litter accumulation varied among species, with the highest C accumulated in the litter under the deciduous species (Populus alba L.). No differences were observed in the amount of total soil organic C among the studied species, or in the concentrations of phenols and sugars in the dissolved organic C (DOC), which might have indicated differences in the biodegradability of the DOC. Microbial biomass and activity was highly influenced by soil pH, and plant species had a significant influence on soil pH in the more acidic site. Soil CO2 fluxes were more influenced by the plant species than total soil C content. Our results suggest that changes in total soil C stocks after the afforestation of degraded Mediterranean

  12. Soil moisture effects during bioventing in fuel-contaminated arid soils

    International Nuclear Information System (INIS)

    Zwick, T.C.; Leeson, A.; Hinchee, R.E.; Hoeppel, R.E.; Bowling, L.

    1995-01-01

    This study evaluated the effects of soil moisture addition on microbial activity during bioventing of dry, sandy soils at the Marine Corps Air Ground Combat Center (MCAGCC), Twentynine Palms, California. Soils at the site have been contaminated to a depth of approximately 80 ft (24 m) with gasoline, JP-5 jet fuel, and diesel fuel. Based on the low soil moisture measured at the site (2 to 3% by weight), it was determined that soil moisture may be limiting biodegradation. To evaluate the effect that moisture addition had on microbial activity under field conditions, a subsurface drip irrigation system was installed above the fuel hydrocarbon plume. Irrigation water was obtained from two monitoring wells on the site, where groundwater was approximately 192 ft (59 m) below ground surface. Advancement of the wetting front was monitored. In situ respiration rates increased significantly after moisture addition. The results of this study provide evidence for the potential applicability of moisture addition in conjunction with bioventing for site remediation in arid environments. Further work is planned to investigate optimization of moisture addition

  13. The Effect of EDTA and Citric acid on Soil Enzymes Activity, Substrate Induced Respiration and Pb Availability in a Contaminated Soil

    Directory of Open Access Journals (Sweden)

    seyed sajjad hosseini

    2017-03-01

    determined by standard methods after 7, 14, 21 and 28 days of chelates addition. Results and Discussion: The soil texture was loam and the indigenous Pb content was 25.55 mg kg-1. The soil pH was 7.4 and electrical conductivity of saturated extraction measured 2.5 dS m-1. The soil carbonate calcium was 14% and the content of organic carbon and essential nutrients were low. The results showed that EDTA3 and EDTA5 treatments increased Pb availability by 2.17% and 10% compared to control treatment but CA3 and CA5 treatments decreased it by 3.8% and 15.7% respectively. The Pb availability in control and EDTA5 treatments did not change during the incubation time. The available Pb concentration dropped sharply during the incubation time in EDTA3, CA3 and CA5 treatments. The reduction rates in CA3 and CA5 treatments were more than EDTA3 treatment. This may be due to the high stability and low biodegradability of EDTA than biodegradable chelators and low molecular weight organic acids. The results showed that urease and dehydrogenase activities were significantly reduced in EDTA3 and EDTA5 treatments compared to control treatment. Urease and dehydrogenase activities were decreased with the increase of EDTA concentration. Alkaline phosphomonoesterase activity was not affected by the EDTA3 and EDTA5 treatments. In CA3 and CA5 treatments, dehydrogenase and alkaline phosphomonoesterase activities significantly increased with increasing the concentration of citric acid. CA5 treatment showed a prominent effect on urease activity compare to CA3 treatment. The soil enzyme activities increased with incubation time. It seems that reduction in Pb availability causes an increase of soil enzymes activities. Significant negative relationships were found between soil enzymes activities and available Pb concentration (dehydrogenase activity (r=-0.906, P

  14. Soil Quality Impacts of Current South American Agricultural Practices

    Directory of Open Access Journals (Sweden)

    Ana B. Wingeyer

    2015-02-01

    Full Text Available Increasing global demand for oil seeds and cereals during the past 50 years has caused an expansion in the cultivated areas and resulted in major soil management and crop production changes throughout Bolivia, Paraguay, Uruguay, Argentina and southern Brazil. Unprecedented adoption of no-tillage as well as improved soil fertility and plant genetics have increased yields, but the use of purchased inputs, monocropping i.e., continuous soybean (Glycine max (L. Merr., and marginal land cultivation have also increased. These changes have significantly altered the global food and feed supply role of these countries, but they have also resulted in various levels of soil degradation through wind and water erosion, soil compaction, soil organic matter (SOM depletion, and nutrient losses. Sustainability is dependent upon local interactions between soil, climate, landscape characteristics, and production systems. This review examines the region’s current soil and crop conditions and summarizes several research studies designed to reduce or prevent soil degradation. Although the region has both environmental and soil resources that can sustain current agricultural production levels, increasing population, greater urbanization, and more available income will continue to increase the pressure on South American croplands. A better understanding of regional soil differences and quantifying potential consequences of current production practices on various soil resources is needed to ensure that scientific, educational, and regulatory programs result in land management recommendations that support intensification of agriculture without additional soil degradation or other unintended environmental consequences.

  15. Acclimation and soil moisture constrain sugar maple root respiration in experimentally warmed soil.

    Science.gov (United States)

    Jarvi, Mickey P; Burton, Andrew J

    2013-09-01

    The response of root respiration to warmer soil can affect ecosystem carbon (C) allocation and the strength of positive feedbacks between climatic warming and soil CO2 efflux. This study sought to determine whether fine-root (maple (Acer saccharum Marsh.)-dominated northern hardwood forest would adjust to experimentally warmed soil, reducing C return to the atmosphere at the ecosystem scale to levels lower than that would be expected using an exponential temperature response function. Infrared heating lamps were used to warm the soil (+4 to +5 °C) in a mature sugar maple forest in a fully factorial design, including water additions used to offset the effects of warming-induced dry soil. Fine-root-specific respiration rates, root biomass, root nitrogen (N) concentration, soil temperature and soil moisture were measured from 2009 to 2011, with experimental treatments conducted from late 2010 to 2011. Partial acclimation of fine-root respiration to soil warming occurred, with soil moisture deficit further constraining specific respiration rates in heated plots. Fine-root biomass and N concentration remained unchanged. Over the 2011 growing season, ecosystem root respiration was not significantly greater in warmed soil. This result would not be predicted by models that allow respiration to increase exponentially with temperature and do not directly reduce root respiration in drier soil.

  16. [Soil Olsen-P content changing trend and i