WorldWideScience

Sample records for wintertime soil carbon

  1. Source Contributions to Wintertime Elemental and Organic Carbon in the Western Arctic Based on Radiocarbon and Tracer Apportionment.

    Science.gov (United States)

    Barrett, T E; Robinson, E M; Usenko, S; Sheesley, R J

    2015-10-06

    To quantify the contributions of fossil and biomass sources to the wintertime Arctic aerosol burden source apportionment is reported for elemental (EC) and organic carbon (OC) fractions of six PM10 samples collected during a wintertime (2012-2013) campaign in Barrow, AK. Radiocarbon apportionment of EC indicates that fossil sources contribute an average of 68 ± 9% (0.01-0.07 μg m(-3)) in midwinter decreasing to 49 ± 6% (0.02 μg m(-3)) in late winter. The mean contribution of fossil sources to OC for the campaign was stable at 38 ± 8% (0.04-0.32 μg m(-3)). Samples were also analyzed for organic tracers, including levoglucosan, for use in a chemical mass balance (CMB) source apportionment model. The CMB model was able to apportion 24-53% and 99% of the OC and EC burdens, respectively, during the campaign, with fossil OC contributions ranging from 25 to 74% (0.02-0.09 μg m(-3)) and fossil EC contributions ranging from 73 to 94% (0.03-0.07 μg m(-3)). Back trajectories identified two major wintertime source regions to Barrow: the Russian and North American Arctic. Atmospheric lifetimes of levoglucosan, ranging from 50 to 320 h, revealed variability in wintertime atmospheric processing of this biomass burning tracer. This study allows for unambiguous apportionment of EC to fossil fuel and biomass combustion sources and intercomparison with CMB modeling.

  2. Potential impacts of wintertime soil moisture anomalies from agricultural irrigation at low latitudes on regional and global climates

    Science.gov (United States)

    Wey, Hao-Wei; Lo, Min-Hui; Lee, Shih-Yu; Yu, Jin-Yi; Hsu, Huang-Hsiung

    2015-10-01

    Anthropogenic water management can change surface energy budgets and the water cycle. In this study, we focused on impacts of Asian low-latitude irrigation on regional and global climates during boreal wintertime. A state-of-the-art Earth system model is used to simulate the land-air interaction processes affected by irrigation and the consequent responses in atmospheric circulation. Perturbed experiments show that wet soil moisture anomalies at low latitudes can reduce the surface temperature on a continental scale through atmospheric feedback. The intensity of prevailing monsoon circulation becomes stronger because of larger land-sea thermal contrast. Furthermore, anomalous upper level convergence over South Asia and midlatitude climatic changes indicate tropical-extratropical teleconnections. The wintertime Aleutian low is deepened and an anomalous warm surface temperature is found in North America. Previous studies have noted this warming but left it unexplained, and we provide plausible mechanisms for these remote impacts coming from the irrigation over Asian low-latitude regions.

  3. Robotic observations of high wintertime carbon export in California coastal waters

    Science.gov (United States)

    Bishop, James K. B.; Fong, Michael B.; Wood, Todd J.

    2016-05-01

    Biologically mediated particulate organic and inorganic carbon (POC and PIC) export from surface waters is the principal determinant of the vertical oceanic distribution of pH and dissolved inorganic carbon and thus sets the conditions for air-sea exchange of CO2; exported organic matter also provides the energy fueling communities in the mesopelagic zone. However, observations are temporally and spatially sparse. Here we report the first hourly-resolved optically quantified POC and PIC sedimentation rate time series from an autonomous Lagrangian Carbon Flux Explorer (CFE), which monitored particle flux using an imaging optical sedimentation recorder (OSR) at depths below 140 m in the Santa Cruz Basin, CA, in May 2012, and in January and March 2013. Highest POC vertical flux ( ˜ 100-240 mmol C m-2 d-1) occurred in January, when most settling material was millimeter- to centimeter-sized aggregates but when surface biomass was low; fluxes were ˜ 18 and ˜ 6 mmol C m-2 d-1, respectively, in March and May, under high surface biomass conditions. An unexpected discovery was that January 2013 fluxes measured by CFE were 20 times higher than that measured by simultaneously deployed surface-tethered OSR; multiple lines of evidence indicate strong undersampling of aggregates larger than 1 mm in the latter case. Furthermore, the January 2013 CFE fluxes were about 10 times higher than observed during multiyear sediment trap observations in the nearby Santa Barbara and San Pedro basins. The strength of carbon export in biologically dynamic California coastal waters is likely underestimated by at least a factor of 3 and at times by a factor of 20.

  4. Size distribution, mixing state and source apportionment of black carbon aerosol in London during wintertime

    Science.gov (United States)

    Liu, D.; Allan, J. D.; Young, D. E.; Coe, H.; Beddows, D.; Fleming, Z. L.; Flynn, M. J.; Gallagher, M. W.; Harrison, R. M.; Lee, J.; Prevot, A. S. H.; Taylor, J. W.; Yin, J.; Williams, P. I.; Zotter, P.

    2014-09-01

    Black carbon aerosols (BC) at a London urban site were characterised in both winter- and summertime 2012 during the Clean Air for London (ClearfLo) project. Positive matrix factorisation (PMF) factors of organic aerosol mass spectra measured by a high-resolution aerosol mass spectrometer (HR-AMS) showed traffic-dominant sources in summer but in winter the influence of additional non-traffic sources became more important, mainly from solid fuel sources (SF). Measurements using a single particle soot photometer (SP2, DMT), showed the traffic-dominant BC exhibited an almost uniform BC core size (Dc) distribution with very thin coating thickness throughout the detectable range of Dc. However, the size distribution of sf (project average mass median Dc = 149 ± 22 nm in winter, and 120 ± 6 nm in summer) and BC coating thickness varied significantly in winter. A novel methodology was developed to attribute the BC number concentrations and mass abundances from traffic (BCtr) and from SF (BCsf), by using a 2-D histogram of the particle optical properties as a function of BC core size, as measured by the SP2. The BCtr and BCsf showed distinctly different sf distributions and coating thicknesses, with BCsf displaying larger Dc and larger coating thickness compared to BCtr. BC particles from different sources were also apportioned by applying a multiple linear regression between the total BC mass and each AMS-PMF factor (BC-AMS-PMF method), and also attributed by applying the absorption spectral dependence of carbonaceous aerosols to 7-wavelength Aethalometer measurements (Aethalometer method). Air masses that originated from westerly (W), southeasterly (SE), and easterly (E) sectors showed BCsf fractions that ranged from low to high, and whose mass median Dc values were 137 ± 10 nm, 143 ± 11 nm and 169 ± 29 nm, respectively. The corresponding bulk relative coating thickness of BC (coated particle size/BC core - Dp/Dc) for these same sectors was 1.28 ± 0.07, 1.45 ± 0

  5. Soil carbon 4 per mille

    OpenAIRE

    Minasny, B.; Malone, B. P.; McBratney, A. B.; Angers, D. A.; Arrouays, D.; Chambers, A.; Chaplot, Vincent; Chen, Z. S.; Cheng, K.; Das, B. S.; Field, D. J.; Gimona, A.; Hedley, C. B.; Hong, S. Y.; Mandal, B.

    2017-01-01

    The '4 per mille Soils for Food Security and Climate' was launched at the COP21 with an aspiration to increase global soil organic matter stocks by 4 per 1000 (or 0.4 %) per year as a compensation for the global emissions of greenhouse gases by anthropogenic sources. This paper surveyed the soil organic carbon (SOC) stock estimates and sequestration potentials from 20 regions in the world (New Zealand, Chile, South Africa, Australia, Tanzania, Indonesia, Kenya, Nigeria, India, China Taiwan, S...

  6. Soil Carbon 4 per mille

    Science.gov (United States)

    Minasny, Budiman; van Wesemael, Bas

    2017-04-01

    The '4 per mille Soils for Food Security and Climate' was launched at the COP21 aiming to increase global soil organic matter stocks by 4 per mille (or 0.4 %) per year as a compensation for the global emissions of greenhouse gases by anthropogenic sources. This paper surveyed the soil organic carbon (SOC) stock estimates and sequestration potentials from 20 regions in the world (New Zealand, Chile, South Africa, Australia, Tanzania, Indonesia, Kenya, Nigeria, India, China Taiwan, South Korea, China Mainland, United States of America, France, Canada, Belgium, England & Wales, Ireland, Scotland, and Russia) and asked whether the 4 per mille initiative is feasible. This study highlights region specific efforts and scopes for soil carbon sequestration. Reported soil C sequestration rates generally show that under best management practices, 4 per mille or even higher sequestration rates can be accomplished. High C sequestration rates (up to 10 per mille) can be achieved for soils with low initial SOC stock (topsoil less than 30 t C ha-1), and at the first twenty years after implementation of best management practices. In addition, areas that have reached equilibrium but not at their saturation level will not be able to further increase their sequestration. We found that most studies on SOC sequestration globally only consider topsoil (up to 0.3 m depth), as it is considered to be most affected by management techniques. The 4 per mille initiative was based on a blanket calculation of the whole global soil profile C stock, however the potential to increase SOC is mostly on managed agricultural lands. If we consider 4 per mille on global topsoil of agricultural land, SOC sequestration is about 3.6 Gt C per year, which effectively offset 40% of global anthropogenic greenhouse gas emissions. As a strategy for climate change mitigation, soil carbon sequestration buys time over the next ten to twenty years while other effective sequestration and low carbon technologies become

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

    Science.gov (United States)

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

    2017-10-01

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

  8. Worldwide organic soil carbon and nitrogen data

    Energy Technology Data Exchange (ETDEWEB)

    Zinke, P.J.; Stangenberger, A.G. [Univ. of California, Berkeley, CA (United States). Dept. of Forestry and Resource Management; Post, W.M.; Emanual, W.R.; Olson, J.S. [Oak Ridge National Lab., TN (United States)

    1986-09-01

    The objective of the research presented in this package was to identify data that could be used to estimate the size of the soil organic carbon pool under relatively undisturbed soil conditions. A subset of the data can be used to estimate amounts of soil carbon storage at equilibrium with natural soil-forming factors. The magnitude of soil properties so defined is a resulting nonequilibrium values for carbon storage. Variation in these values is due to differences in local and geographic soil-forming factors. Therefore, information is included on location, soil nitrogen content, climate, and vegetation along with carbon density and variation.

  9. Molecular distributions and compound-specific stable carbon isotopic compositions of lipids in wintertime aerosols from Beijing.

    Science.gov (United States)

    Ren, Lujie; Fu, Pingqing; He, Yue; Hou, Juzhi; Chen, Jing; Pavuluri, Chandra Mouli; Sun, Yele; Wang, Zifa

    2016-06-08

    Molecular distributions and stable carbon isotopic compositions (δ(13)C) of n-alkanes, fatty acids and n-alcohols were investigated in urban aerosols from Beijing, northern China to better understand the sources and long-range atmospheric transport of terrestrial organic matter during polluted and clear days in winter. n-Alkanes (C19-C36), fatty acids (C8-C32) and n-alcohols (C16-C32) detected in Beijing aerosols are characterized by the predominance of C23, C16 and C28, respectively. Carbon preference index (CPI) values of n-alkanes, the ratios of the sum of odd-numbered n-alkanes to the sum of even-numbered n-alkanes, are close to 1, indicating a heavy influence of fossil fuel combustion. Relatively higher ratios of C(18:0+16:0)/C(18:n+16:1) (fatty acids) on clear days than polluted days indicate that long-distance transport and/or photochemical aging are more significant during clear days. δ(13)C values of n-alkanes and low molecular weight fatty acids (C16:0, C18:0) ranged from -34.1 to -24.7% and -26.9 to -24.6%, respectively, which are generally heavier on polluted days than those on clear days. Such a wide range suggests that atmospheric lipids in Beijing aerosols originate from multiple sources and encounter complicated atmospheric processes during long-range transport in North China.

  10. Erosion of soil organic carbon: implications for carbon sequestration

    Science.gov (United States)

    Van Oost, Kristof; Van Hemelryck, Hendrik; Harden, Jennifer W.; McPherson, B.J.; Sundquist, E.T.

    2009-01-01

    Agricultural activities have substantially increased rates of soil erosion and deposition, and these processes have a significant impact on carbon (C) mineralization and burial. Here, we present a synthesis of erosion effects on carbon dynamics and discuss the implications of soil erosion for carbon sequestration strategies. We demonstrate that for a range of data-based parameters from the literature, soil erosion results in increased C storage onto land, an effect that is heterogeneous on the landscape and is variable on various timescales. We argue that the magnitude of the erosion term and soil carbon residence time, both strongly influenced by soil management, largely control the strength of the erosion-induced sink. In order to evaluate fully the effects of soil management strategies that promote carbon sequestration, a full carbon account must be made that considers the impact of erosion-enhanced disequilibrium between carbon inputs and decomposition, including effects on net primary productivity and decomposition rates.

  11. Soil Carbon Data: long tail recovery

    Energy Technology Data Exchange (ETDEWEB)

    2017-07-25

    The software is intended to be part of an open source effort regarding soils data. The software provides customized data ingestion scripts for soil carbon related data sets and scripts for output databases that conform to common templates.

  12. Carbon sequestration in agricultural soils: a potential carbon trading opportunity?

    International Nuclear Information System (INIS)

    Cowie, Annette L.; Murphy, Brian; Rawson, Andrew; Wilson, Brian; Singh, Bhupinderpal; Young, Rick; Grange, Ian

    2007-01-01

    Full text: Emissions trading schemes emerging in Australia and internationally create a market mechanism by which release of greenhouse gases incurs a cost, and implementation of abatement measures generates a financial return. There is growing interest amongst Australian landholders in emissions trading based on sequestration of carbon in soil through modified land management practices. Intensively cropped soils have low carbon content, due to disturbance, erosion and regular periods of minimal organic matter input. Because cropping soils in Australia have lost a substantial amount of carbon there is significant potential to increase carbon stocks through improved land management practices. Evidence from long term trials and modelling indicates that modified cropping practices (direct drilling, stubble retention, controlled traffic) have limited impact on soil carbon (0 to +2 tC02e ha-' year1) whereas conversion from cropping to pasture gives greater increases. Small-increases in soil carbon over large areas can contribute significantly to mitigation of Australia's greenhouse gas emissions. Furthermore, increase in soil organic matter will improve soil health, fertility and resilience. However, the inclusion of soil carbon offsets in an emissions trading scheme cannot occur until several barriers are overcome. The first relates to credibility. Quantification of the extent to which specific land management practices can sequester carbon in different environments will provide the basis for promotion of the concept. Current research across Australia is addressing this need. Secondly, cost-effective and accepted methods of estimating soil carbon change must be available. Monitoring soil carbon to document change on a project scale is not viable due to the enormous variability in carbon stocks on micro and macro scales. Instead estimation of soil carbon change could be undertaken through a combination of baseline measurement to assess the vulnerability of soil carbon

  13. Modelling soil organic carbon in Danish agricultural soils suggests low potential for future carbon sequestration

    DEFF Research Database (Denmark)

    Taghizadeh-Toosi, Arezoo; Olesen, Jørgen Eivind

    2016-01-01

    Soil organic carbon (SOC) is in active exchange with the atmosphere. The amount of organic carbon (OC) input into the soil and SOC turnover rate are important for predicting the carbon (C) sequestration potential of soils subject to changes in land-use and climate. The C-TOOL model was developed...

  14. Review of progress in soil inorganic carbon research

    Science.gov (United States)

    Bai, S. G.; Jiao, Y.; Yang, W. Z.; Gu, P.; Yang, J.; Liu, L. J.

    2017-12-01

    Soil inorganic carbon is one of the main carbon banks in the near-surface environment, and is the main form of soil carbon library in arid and semi-arid regions, which plays an important role in the global carbon cycle. This paper mainly focuses on the inorganic dynamic process of soil inorganic carbon in soil environment in arid and semi-arid regions, and summarized the composition and source of soil inorganic carbon, influence factors and soil carbon sequestration.

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

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  16. Rates of calcium carbonate removal from soils.

    NARCIS (Netherlands)

    Breemen, van N.; Protz, R.

    1988-01-01

    Mean annual rates of calcium carbonate removal from soils in a subarctic climate estimated from data on two chronosequences of calcareous storm ridges, appeared to be relatively constant through time. Concentrations of dissolved calcium carbonate in the soil solution in the study sites calculated

  17. Carbon dioxide emissions from biochar in soil

    DEFF Research Database (Denmark)

    Bruun, Sander; Clauson-Kaas, Anne Sofie Kjærulff; Bobuľská, L.

    2014-01-01

    The stability of biochar in soil is of importance if it is to be used for carbon sequestration and long-term improvement of soil properties. It is well known that a significant fraction of biochar is highly stable in soil, but carbon dioxide (CO2) is also released immediately after application....... This study investigated the nature of the early release of CO2 and the degree to which stabilizing mechanisms protect biochar from microbial attack. Incubations of 14C-labelled biochar produced at different temperatures were performed in soils with different clay contents and in sterilized and non......-sterilized soils. It emerged that carbonate may be concentrated or form during or after biochar production, resulting in significant carbonate contents. If CO2 released from carbonates in short-term experiments is misinterpreted as mineralization of biochar, the impact of this process may be significantly over...

  18. Transformations of carbon hydrocarbon-contaminated soils

    International Nuclear Information System (INIS)

    Bailey, V. L.

    1999-01-01

    Carbon 1 4 labelled organic contaminants were used to describe the transformation of petroleum-derived hydrocarbons into new biomass, carbon dioxide, or partially transformed metabolites by soil microorganisms in two aged contaminated soil samples. Both soils have mineralized 50 per cent of the applied C 1 4 to 14 C O 2 within the first three months of a 12-month incubation period. The addition of dichloromethane to these soils reduced the degree to which the contaminants were transformed. There was a 50 per cent decrease in oil-contaminated soil and a 98 per cent decrease in soil contaminated by creosote. The addition of non-type model organic contaminants appeared to limit the ability of indigenous micro-organism to mineralize the soil. It appears that contaminant-derived carbon is no obstacle to bioremediation; rather, the compounds added simply serve as additional substrate for the indigenous microbial populations

  19. Transformations of carbon hydrocarbon-contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, V. L.

    1999-07-01

    Carbon{sup 1}4 labelled organic contaminants were used to describe the transformation of petroleum-derived hydrocarbons into new biomass, carbon dioxide, or partially transformed metabolites by soil microorganisms in two aged contaminated soil samples. Both soils have mineralized 50 per cent of the applied C{sup 1}4 to 14{sup C}O{sub 2} within the first three months of a 12-month incubation period. The addition of dichloromethane to these soils reduced the degree to which the contaminants were transformed. There was a 50 per cent decrease in oil-contaminated soil and a 98 per cent decrease in soil contaminated by creosote. The addition of non-type model organic contaminants appeared to limit the ability of indigenous micro-organism to mineralize the soil. It appears that contaminant-derived carbon is no obstacle to bioremediation; rather, the compounds added simply serve as additional substrate for the indigenous microbial populations.

  20. How does soil management affect carbon losses from soils?

    Science.gov (United States)

    Klik, A.; Trümper, G.

    2009-04-01

    Agricultural soils are a major source as well as a sink of organic carbon (OC). Amount and distribution of OC within the soil and within the landscape are driven by land management but also by erosion and deposition processes. At the other hand the type of soil management influences mineralization and atmospheric carbon dioxide losses by soil respiration. In a long-term field experiment the impacts of soil tillage systems on soil erosion processes were investigated. Following treatments were compared: 1) conventional tillage (CT), 2) conservation tillage with cover crop during the winter period (CS), and 3) no-till with cover crop during winter period (NT). The studies were carried out at three sites in the Eastern part of Austria with annual precipitation amounts from 650 to 900 mm. The soil texture ranged from silt loam to loam. Since 2007 soil CO2 emissions are measured with a portable soil respiration system in intervals of about one week, but also in relation to management events. Concurrent soil temperature and soil water content are measured and soil samples are taken for chemical and microbiological analyses. An overall 14-yr. average soil loss between 1.0 t.ha-1.yr-1 for NT and 6.1 t.ha-1.yr-1 for CT resulted in on-site OC losses from 18 to 79 kg ha-1.yr-1. The measurements of the carbon dioxide emissions from the different treatments indicate a high spatial variation even within one plot. Referred to CT plots calculated carbon losses amounted to 65-94% for NT plots while for the different RT plots they ranged between 84 and 128%. Nevertheless site specific considerations have to be taken into account. Preliminary results show that the adaptation of reduced or no-till management strategies has enormous potential in reducing organic carbon losses from agricultural used soils.

  1. Soil carbon stocks in Sarawak, Malaysia

    Energy Technology Data Exchange (ETDEWEB)

    Padmanabhan, E., E-mail: Eswaran_padmanabhan@petronas.com.my [Department of Geosciences, Faculty of Geosciences and Petroleum Engineering, Universiti Teknologi PETRONAS, Tronoh, 31750, Perak (Malaysia); Eswaran, H.; Reich, P.F. [USDA-Natural Resources Conservation Service, Washington, DC 20250 (United States)

    2013-11-01

    The relationship between greenhouse gas emission and climate change has led to research to identify and manage the natural sources and sinks of the gases. CO{sub 2}, CH{sub 4}, and N{sub 2}O have an anthropic source and of these CO{sub 2} is the least effective in trapping long wave radiation. Soil carbon sequestration can best be described as a process of removing carbon dioxide from the atmosphere and relocating into soils in a form that is not readily released back into the atmosphere. The purpose of this study is to estimate carbon stocks available under current conditions in Sarawak, Malaysia. SOC estimates are made for a standard depth of 100 cm unless the soil by definition is less than this depth, as in the case of lithic subgroups. Among the mineral soils, Inceptisols tend to generally have the highest carbon contents (about 25 kg m{sup −2} m{sup −1}), while Oxisols and Ultisols rate second (about 10–15 kg m{sup −2} m{sup −1}). The Oxisols store a good amount of carbon because of an appreciable time-frame to sequester carbon and possibly lower decomposition rates for the organic carbon that is found at 1 m depths. Wet soils such as peatlands tend to store significant amounts of carbon. The highest values estimated for such soils are about 114 kg m{sup −2} m{sup −1}. Such appreciable amounts can also be found in the Aquepts. In conclusion, it is pertinent to recognize that degradation of the carbon pool, just like desertification, is a real process and that this irreversible process must be addressed immediately. Therefore, appropriate soil management practices should be instituted to sequester large masses of soil carbon on an annual basis. This knowledge can be used effectively to formulate strategies to prevent forest fires and clearing: two processes that can quickly release sequestered carbon to the atmosphere in an almost irreversible manner. - Highlights: • Soil carbon stocks in different soils in Sarawak • In depth discussion of

  2. Communicating soil carbon science to farmers

    DEFF Research Database (Denmark)

    Ingram, Julie; Mills, Jane; Dibari, Camilla

    2016-01-01

    Abstract A key narrative within climate change science is that conserving and improving soil carbon through agricultural practices can contribute to agricultural productivity and is a promising option for mitigating carbon loss through sequestration. This paper examines the potential disconnect...... between science and practice in the context of communicating information about soil carbon management. It focuses on the information producing process and on stakeholder (adviser, farmer representative, policy maker etc) assessment of the attributes credibility, salience and legitimacy. In doing...

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

    Science.gov (United States)

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

    2014-03-01

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

  4. Soil carbon stocks in Sarawak, Malaysia.

    Science.gov (United States)

    Padmanabhan, E; Eswaran, H; Reich, P F

    2013-11-01

    The relationship between greenhouse gas emission and climate change has led to research to identify and manage the natural sources and sinks of the gases. CO2, CH4, and N2O have an anthropic source and of these CO2 is the least effective in trapping long wave radiation. Soil carbon sequestration can best be described as a process of removing carbon dioxide from the atmosphere and relocating into soils in a form that is not readily released back into the atmosphere. The purpose of this study is to estimate carbon stocks available under current conditions in Sarawak, Malaysia. SOC estimates are made for a standard depth of 100 cm unless the soil by definition is less than this depth, as in the case of lithic subgroups. Among the mineral soils, Inceptisols tend to generally have the highest carbon contents (about 25 kg m(-2) m(-1)), while Oxisols and Ultisols rate second (about 10-15 kg m(-2) m(-1)). The Oxisols store a good amount of carbon because of an appreciable time-frame to sequester carbon and possibly lower decomposition rates for the organic carbon that is found at 1m depths. Wet soils such as peatlands tend to store significant amounts of carbon. The highest values estimated for such soils are about 114 kg m(-2) m(-1). Such appreciable amounts can also be found in the Aquepts. In conclusion, it is pertinent to recognize that degradation of the carbon pool, just like desertification, is a real process and that this irreversible process must be addressed immediately. Therefore, appropriate soil management practices should be instituted to sequester large masses of soil carbon on an annual basis. This knowledge can be used effectively to formulate strategies to prevent forest fires and clearing: two processes that can quickly release sequestered carbon to the atmosphere in an almost irreversible manner. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Sequestration of Soil Carbon as Secondary Carbonates (Invited)

    Science.gov (United States)

    Lal, R.

    2013-12-01

    Rattan Lal Carbon Management and Sequestration Center The Ohio State University Columbus, OH 43210 USA Abstract World soils, the major carbon (C) reservoir among the terrestrial pools, contain soil organic C (SOC) and soil inorganic C (SIC). The SIC pool is predominant in soils of arid and semi-arid regions. These regions cover a land area of about 4.9x109 ha. The SIC pool in soils containing calcic and petrocalcic horizons is estimated at about 695-748 Pg (Pg = 1015 g = 1 gigaton) to 1-m depth. There are two types of carbonates. Lithogenic or primary carbonates are formed from weathering of carbonaceous rocks. Pedogenic or secondary carbonates are formed by dissolution of CO2 in the soil air to form carbonic acid and precipitation as carbonates of Ca+2 or Mg+2. It is the availability of Ca+2 or Mg+2 from outside the ecosystem that is essential to sequester atmospheric CO2. Common among outside sources of Ca+2 or Mg+2 are irrigation water, aerial deposition, sea breeze, fertilizers, manure and other amendments. The decomposition of SOC and root respiration may increase the partial pressure of CO2 in the soil air and lead to the formation of HCO_3^- upon dissolution in H20. Precipitation of secondary carbonates may result from decreased partial pressure of CO2 in the sub-soil, increased concentration of Ca+2, Mg+2 and HCO_3^- in soil solution, and decreased soil moisture content by evapotranspiration. Transport of bicarbonates in irrigated soils and subsequent precipitation above the ground water (calcrete), activity of termites and other soil fauna, and management of urban soils lead to formation of secondary carbonates. On a geologic time scale, weathering of silicate minerals and transport of the by-products into the ocean is a geological process of sequestration of atmospheric CO2. Factors affecting formation of secondary carbonates include land use, and soil and crop management including application of biosolids, irrigation and the quality of irrigation water

  6. [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.

  7. Soil Carbon Sequestration Resulting from Biosolids Application

    Directory of Open Access Journals (Sweden)

    Silvana I. Torri

    2014-01-01

    Full Text Available Carbon (C sequestration in soils through the increase of the soil organic carbon (SOC pool has generated broad interest to mitigate the effects of climate change. Biosolids soil application may represent a persistent increase in the SOC pool. While a vast literature is available on the value of biosolids as a soil conditioner or nutrient source in agricultural systems, there is still limited knowledge on soil sequestration mechanisms of biosolids-borne C or the main factors influencing this capacity. The emerging challenges posed by global environmental changes and the stringent needs to enhance C storage call for more research on the potential of soil biosolids incorporation as a sustainable C storage practice. This review addresses the potential of C sequestration of agricultural soils and opencast mines amended with biosolids and its biological regulation.

  8. Stocks of organic carbon in Estonian soils

    Directory of Open Access Journals (Sweden)

    Kõlli, Raimo

    2009-06-01

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

  9. The effect of soil fauna on carbon sequestration in soil

    Czech Academy of Sciences Publication Activity Database

    Frouz, Jan; Pižl, Václav; Kaneda, Satoshi; Šimek, Miloslav

    2008-01-01

    Roč. 10, - (2008) ISSN 1029-7006. [EGU General Assembly 2008. 13.04.2008-18.04.2008, Vienna] Institutional research plan: CEZ:AV0Z60660521 Keywords : soil fauna * carbon sequestration * soil Subject RIV: EH - Ecology, Behaviour

  10. Uncertainty in soil carbon accounting due to unrecognized soil erosion.

    Science.gov (United States)

    Sanderman, Jonathan; Chappell, Adrian

    2013-01-01

    The movement of soil organic carbon (SOC) during erosion and deposition events represents a major perturbation to the terrestrial carbon cycle. Despite the recognized impact soil redistribution can have on the carbon cycle, few major carbon accounting models currently allow for soil mass flux. Here, we modified a commonly used SOC model to include a soil redistribution term and then applied it to scenarios which explore the implications of unrecognized erosion and deposition for SOC accounting. We show that models that assume a static landscape may be calibrated incorrectly as erosion of SOC is hidden within the decay constants. This implicit inclusion of erosion then limits the predictive capacity of these models when applied to sites with different soil redistribution histories. Decay constants were found to be 15-50% slower when an erosion rate of 15 t soil ha(-1)  yr(-1) was explicitly included in the SOC model calibration. Static models cannot account for SOC change resulting from agricultural management practices focused on reducing erosion rates. Without accounting for soil redistribution, a soil sampling scheme which uses a fixed depth to support model development can create large errors in actual and relative changes in SOC stocks. When modest levels of erosion were ignored, the combined uncertainty in carbon sequestration rates was 0.3-1.0 t CO2  ha(-1)  yr(-1) . This range is similar to expected sequestration rates for many management options aimed at increasing SOC levels. It is evident from these analyses that explicit recognition of soil redistribution is critical to the success of a carbon monitoring or trading scheme which seeks to credit agricultural activities. © 2012 Blackwell Publishing Ltd.

  11. quantifying the stock of soil organic carbon using multiple regression

    African Journals Online (AJOL)

    Osondu

    2012-03-15

    Mar 15, 2012 ... Depending on the changes in the level of soil organic matter, soils can act as sinks of carbon concentration in the atmosphere, thereby increasing the concentration of carbon in the soil. (Dey, 2005). Therefore, soils according to Lal,. (2005) are the largest carbon reservoir of the terrestrial carbon cycle, this is ...

  12. NON-DESTRUCTIVE SOIL CARBON ANALYZER.

    Energy Technology Data Exchange (ETDEWEB)

    Wielopolski, Lucian; Hendrey, G.; Orion, I.; Prior, S.; Rogers, H.; Runion, B.; Torbert, A.

    2004-02-01

    This report describes the feasibility, calibration, and safety considerations of a non-destructive, in situ, quantitative, volumetric soil carbon analytical method based on inelastic neutron scattering (INS). The method can quantify values as low as 0.018 gC/cc, or about 1.2% carbon by weight with high precision under the instrument's configuration and operating conditions reported here. INS is safe and easy to use, residual soil activation declines to background values in under an hour, and no radiological requirements are needed for transporting the instrument. The labor required to obtain soil-carbon data is about 10-fold less than with other methods, and the instrument offers a nearly instantaneous rate of output of carbon-content values. Furthermore, it has the potential to quantify other elements, particularly nitrogen. New instrumentation was developed in response to a research solicitation from the U.S. Department of Energy (DOE LAB 00-09 Carbon Sequestration Research Program) supporting the Terrestrial Carbon Processes (TCP) program of the Office of Science, Biological and Environmental Research (BER). The solicitation called for developing and demonstrating novel techniques for quantitatively measuring changes in soil carbon. The report includes raw data and analyses of a set of proof-of-concept, double-blind studies to evaluate the INS approach in the first phase of developing the instrument. Managing soils so that they sequester massive amounts of carbon was suggested as a means to mitigate the atmospheric buildup of anthropogenic CO{sub 2}. Quantifying changes in the soils' carbon stocks will be essential to evaluating such schemes and documenting their performance. Current methods for quantifying carbon in soil by excavation and core sampling are invasive, slow, labor-intensive and locally destroy the system being observed. Newly emerging technologies, such as Laser Induced Breakdown Spectroscopy and Near-Infrared Spectroscopy, offer soil-carbon

  13. Afforestation effects on soil carbon

    DEFF Research Database (Denmark)

    Bárcena, Teresa G

    Protocol. Despite research efforts on the quantification of SOC stock change and soil C fluxes following this land-use change, knowledge is still scarce in regions where afforestation currently is and has been widespread, like Denmark and the rest of Northern Europe. This PhD thesis explored three main...... aspects of the impact of afforestation on soil C: i) changes in SOC stocks (in forest floors and mineral soils) on afforested cropland in Denmark and in afforested soils of Northern Europe; ii) changes in CH4 oxidation (uptake) potential of soils; iii) changes in soil CO2 efflux through heterotrophic...... balance between soil compartments over time, with C accumulation in the mineral soil becoming increasingly important as the sink strength of forest floors decreased within 4 decades of afforestation. The chronosequence approach is an appropriate tool to assess SOC stock changes following afforestation...

  14. Soil Carbon: Compositional and Isotopic Analysis

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-11-01

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

  15. Soil carbon 4 per mille

    NARCIS (Netherlands)

    Mulder, V.L.

    2017-01-01

    The ‘4 per mille Soils for Food Security and Climate’ was launched at the COP21 with an aspiration to increase global soil organic matter stocks by 4 per 1000 (or 0.4 %) per year as a compensation for the global emissions of greenhouse gases by anthropogenic sources. This paper surveyed the soil

  16. Carbon in boreal coniferous forest soil

    Energy Technology Data Exchange (ETDEWEB)

    Westman, C.J.; Ilvesniemi, H.; Liski, J.; Mecke, M. [Helsinki Univ. (Finland). Dept. of Forest Ecology; Fritze, H.; Helmisaari, H.S.; Pietikaeinen, J.; Smolander, A. [Finnish Forest Research Inst., Vantaa (Finland)

    1996-12-31

    The working hypothesis of the research was that the soil of boreal forests is a large carbon store and the amount of C is still increasing in young soils, like in the forest soils of Finland, which makes these soils important sinks for atmospheric CO{sub 2}. Since the processes defining the soil C balance, primary production of plants and decomposition, are dependent on environmental factors and site properties, it was assumed that the organic carbon pool in the soil is also dependent on the same factors. The soil C store is therefore likely to change in response to climatic warming. The aim of this research was to estimate the C balance of forest soil in Finland and predict changes in the balance in response to changes in climatic conditions. To achieve the aim (1) intensive empirical experimentation on the density of C in different pools in the soil and on fluxes between the pools was done was done, (2) the effect of site fertility and climate on the amount and properties of organic C in forest soil was investigated and (3) dynamic modelling for investigating dynamics of the soil C storage was used

  17. Black Carbon Contribution to Organic Carbon Stocks in Urban Soil.

    Science.gov (United States)

    Edmondson, Jill L; Stott, Iain; Potter, Jonathan; Lopez-Capel, Elisa; Manning, David A C; Gaston, Kevin J; Leake, Jonathan R

    2015-07-21

    Soil holds 75% of the total organic carbon (TOC) stock in terrestrial ecosystems. This comprises ecosystem-derived organic carbon (OC) and black carbon (BC), a recalcitrant product of the incomplete combustion of fossil fuels and biomass. Urban topsoils are often enriched in BC from historical emissions of soot and have high TOC concentrations, but the contribution of BC to TOC throughout the urban soil profile, at a regional scale is unknown. We sampled 55 urban soil profiles across the North East of England, a region with a history of coal burning and heavy industry. Through combined elemental and thermogravimetic analyses, we found very large total soil OC stocks (31-65 kg m(-2) to 1 m), exceeding typical values reported for UK woodland soils. BC contributed 28-39% of the TOC stocks, up to 23 kg C m(-2) to 1 m, and was affected by soil texture. The proportional contribution of the BC-rich fraction to TOC increased with soil depth, and was enriched in topsoil under trees when compared to grassland. Our findings establish the importance of urban ecosystems in storing large amounts of OC in soils and that these soils also capture a large proportion of BC particulates emitted within urban areas.

  18. Environmental Controls of Soil Organic Carbon in Soils Across Amazonia

    Science.gov (United States)

    Quesada, Carlos Alberto; Paz, Claudia; Phillips, Oliver; Nonato Araujo Filho, Raimundo; Lloyd, Jon

    2015-04-01

    Amazonian forests store and cycle a significant amount of carbon on its soils and vegetation. Yet, Amazonian forests are now subject to strong environmental pressure from both land use and climate change. Some of the more dramatic model projections for the future of the Amazon predict a major change in precipitation followed by savanization of most currently forested areas, resulting in major carbon losses to the atmosphere. However, how soil carbon stocks will respond to climatic and land use changes depend largely on how soil carbon is stabilized. Amazonian soils are highly diverse, being very variable in their weathering levels and chemical and physical properties, and thus it is important to consider how the different soils of the Basin stabilize and store soil organic carbon (SOC). The wide variation in soil weathering levels present in Amazonia, suggests that soil groups with contrasting pedogenetic development should differ in their predominant mechanism of SOC stabilization. In this study we investigated the edaphic, mineralogical and climatic controls of SOC concentration in 147 pristine forest soils across nine different countries in Amazonia, encompassing 14 different WRB soil groups. Soil samples were collected in 1 ha permanent plots used for forest dynamics studies as part of the RAINFOR project. Only 0-30 cm deep averages are reported here. Soil samples were analyzed for carbon and nitrogen and for their chemical (exchangeable bases, phosphorus, pH) and physical properties, (particle size, bulk density) and mineralogy through standard selective dissolution techniques (Fe and Al oxides) and by semi-quantitative X-Ray diffraction. In Addition, selected soils from each soil group had SOC fractionated by physical and chemical techniques. Our results indicate that different stabilization mechanisms are responsible for SOC stabilization in Amazonian soils with contrasting pedogenetic level. Ferralsols and Acrisols were found to have uniform mineralogy

  19. Soil fauna: key to new carbon models

    Science.gov (United States)

    Filser, Juliane; Faber, Jack H.; Tiunov, Alexei V.; Brussaard, Lijbert; Frouz, Jan; De Deyn, Gerlinde; Uvarov, Alexei V.; Berg, Matty P.; Lavelle, Patrick; Loreau, Michel; Wall, Diana H.; Querner, Pascal; Eijsackers, Herman; José Jiménez, Juan

    2016-11-01

    Soil organic matter (SOM) is key to maintaining soil fertility, mitigating climate change, combatting land degradation, and conserving above- and below-ground biodiversity and associated soil processes and ecosystem services. In order to derive management options for maintaining these essential services provided by soils, policy makers depend on robust, predictive models identifying key drivers of SOM dynamics. Existing SOM models and suggested guidelines for future SOM modelling are defined mostly in terms of plant residue quality and input and microbial decomposition, overlooking the significant regulation provided by soil fauna. The fauna controls almost any aspect of organic matter turnover, foremost by regulating the activity and functional composition of soil microorganisms and their physical-chemical connectivity with soil organic matter. We demonstrate a very strong impact of soil animals on carbon turnover, increasing or decreasing it by several dozen percent, sometimes even turning C sinks into C sources or vice versa. This is demonstrated not only for earthworms and other larger invertebrates but also for smaller fauna such as Collembola. We suggest that inclusion of soil animal activities (plant residue consumption and bioturbation altering the formation, depth, hydraulic properties and physical heterogeneity of soils) can fundamentally affect the predictive outcome of SOM models. Understanding direct and indirect impacts of soil fauna on nutrient availability, carbon sequestration, greenhouse gas emissions and plant growth is key to the understanding of SOM dynamics in the context of global carbon cycling models. We argue that explicit consideration of soil fauna is essential to make realistic modelling predictions on SOM dynamics and to detect expected non-linear responses of SOM dynamics to global change. We present a decision framework, to be further developed through the activities of KEYSOM, a European COST Action, for when mechanistic SOM models

  20. Pressure pumping of carbon dioxide from soil

    Science.gov (United States)

    E. S. Takle; J. R. Brandle; R. A. Schmidt; R. Garcia; I. V. Litvina; G. Doyle; X. Zhou; Q. Hou; C. W. Rice; W. J. Massman

    2000-01-01

    Recent interest in atmospheric increases in carbon dioxide have heightened the need for improved accuracy in measurements of fluxes of carbon dioxide from soils. Diffusional movement has long been considered the dominant process by which trace gases move from the subsurface source to the surface, although there has been some indication that atmospheric pressure...

  1. Studies on enhancing carbon sequestration in soils

    International Nuclear Information System (INIS)

    Marland, G.; Garten, C.T.; Post, W.M.; West, T.O.

    2004-01-01

    Studies of carbon and nitrogen dynamics in ecosystems are leading to an understanding of the factors and mechanisms that affect the inputs to and outputs from soils and how these might be manipulated to enhance C sequestration. Both the quantity and the quality of soil C inputs influence C storage and the potential for C sequestration. Changes in tillage intensity and crop rotations can also affect C sequestration by changing the soil physical and biological conditions and by changing the amounts and types of organic inputs to the soil. Analyses of changes in soil C and N balances are being supplemented with studies of the management practices needed to manage soil carbon and the implications for fossil-fuel use, emission of other greenhouse gases (such as N 2 O and CH 4 ), and impacts on agricultural productivity. The Consortium for Research on Enhancing Carbon Sequestration in Terrestrial Ecosystems (CSiTE) was created in 1999 to perform fundamental research that will lead to methods to enhance C sequestration as one component of a C management strategy. Research to date at one member of this consortium, Oak Ridge National Laboratory, has focused on C sequestration in soils and we begin here to draw together some of the results

  2. Carbon Dioxide in Arable Soil Profiles

    DEFF Research Database (Denmark)

    Chirinda, Ngoni; Plauborg, Finn; Heckrath, Goswin Johann

    2014-01-01

    ; however, differences may occur in response to soil spatial variability. A better coverage of spatial variability is more easily addressed using manually operated systems whereas temporal variability can be covered using the automated system. Depending on the aim of the study, the two systems may be used......Carbon dioxide (CO2) concentrations in arable soil profiles are influenced by autotrophic and heterotrophic respiration as well as soil physical properties that regulate gas transport. Whereas different methods have been used to assess dynamics of soil CO2 concentrations, our understanding...... on the comparability of results obtained using different methods is limited. We therefore aimed to compare the dynamics in soil CO2 concentrations obtained from an automated system (GMP343 sensors) to those from a manually operated measurement system (i.e., soil gas sampled using stainless steel needles and rods...

  3. Measurable Pools of Soil Carbon for Carbon Cycle Modeling

    Science.gov (United States)

    Mayes, M. A.; Wang, G.; Abramoff, R. Z.; Xu, X.; Hartman, M. D.; Feng, W.; Davidson, E.; Finzi, A.; Moorhead, D.; Schimel, J.; O'Brien, S. L.; Thornton, P. E.

    2016-12-01

    Carbon in soils can have long residence times, but the exact mechanisms are not well understood, which complicates defining pools and parameters for carbon cycling models. Physical protection involves the formation of hierarchical aggregates of mineral-associated carbon, microbes, and particulate carbon. Aggregation leads to a complex pore structure, which can alter moisture potentials, gas diffusion rates, ionic strength and composition of soil solutions, and nutrient availability for microbes. Diffusion gradients between pore size classes can also sequester organic materials from microbes and their accompanying enzymes. Mineral protection is considered to involve sorption of dissolved organic compounds onto reactive clays and iron and aluminum oxides, but there is controversy as to whether sorption occurs as a monolayer or in complex architectures, as well as the degree of mineral coverage. Further, pore structure can alter the ionic composition of porewaters, thereby influencing the extent and nature of adsorption and desorption. Only mineral protection is thought to yield the long residence times found in soils, but dynamics of these pools are poorly constrained in models due to an absence of long-term measurements and an accompanying lack of process understanding. This talk will review the evidence for and against these different mechanisms of carbon preservation, with particular attention to definitions of soil pools for modeling and the influence of protection mechanisms on carbon pool residence times.

  4. Carbon monoxide isotopic measurements in Indianapolis constrain urban source isotopic signatures and support mobile fossil fuel emissions as the dominant wintertime CO source

    Directory of Open Access Journals (Sweden)

    Isaac J. Vimont

    2017-11-01

    Full Text Available We present measurements of CO mole fraction and CO stable isotopes (δ13CO and δC18O in air during the winters of 2013–14 and 2014–15 at tall tower sampling sites in and around Indianapolis, USA. A tower located upwind of the city was used to quantitatively remove the background CO signal, allowing for the first unambiguous isotopic characterization of the urban CO source and yielding 13CO of –27.7 ± 0.5‰ VPDB and C18O of 17.7 ± 1.1‰ VSMOW for this source. We use the tower isotope measurements, results from a limited traffic study, as well as atmospheric reaction rates to examine contributions from different sources to the Indianapolis CO budget. Our results are consistent with earlier findings that traffic emissions are the dominant source, suggesting a contribution of 96% or more to the overall Indianapolis wintertime CO emissions. Our results are also consistent with the hypothesis that emissions from a small fraction of vehicles without functional catalytic systems dominate the Indianapolis CO budget.

  5. Dynamics of maize carbon contribution to soil organic carbon in association with soil type and fertility level.

    Science.gov (United States)

    Pei, Jiubo; Li, Hui; Li, Shuangyi; An, Tingting; Farmer, John; Fu, Shifeng; Wang, Jingkuan

    2015-01-01

    Soil type and fertility level influence straw carbon dynamics in the agroecosystems. However, there is a limited understanding of the dynamic processes of straw-derived and soil-derived carbon and the influence of the addition of straw carbon on soil-derived organic carbon in different soils associated with different fertility levels. In this study, we applied the in-situ carborundum tube method and 13C-labeled maize straw (with and without maize straw) at two cropland (Phaeozem and Luvisol soils) experimental sites in northeast China to quantify the dynamics of maize-derived and soil-derived carbon in soils associated with high and low fertility, and to examine how the addition of maize carbon influences soil-derived organic carbon and the interactions of soil type and fertility level with maize-derived and soil-derived carbon. We found that, on average, the contributions of maize-derived carbon to total organic carbon in maize-soil systems during the experimental period were differentiated among low fertility Luvisol (from 62.82% to 42.90), high fertility Luvisol (from 53.15% to 30.00%), low fertility Phaeozem (from 58.69% to 36.29%) and high fertility Phaeozem (from 41.06% to 16.60%). Furthermore, the addition of maize carbon significantly decreased the remaining soil-derived organic carbon in low and high fertility Luvisols and low fertility Phaeozem before two months. However, the increasing differences in soil-derived organic carbon between both soils with and without maize straw after two months suggested that maize-derived carbon was incorporated into soil-derived organic carbon, thereby potentially offsetting the loss of soil-derived organic carbon. These results suggested that Phaeozem and high fertility level soils would fix more maize carbon over time and thus were more beneficial for protecting soil-derived organic carbon from maize carbon decomposition.

  6. Urban tree effects on soil organic carbon.

    Directory of Open Access Journals (Sweden)

    Jill L Edmondson

    Full Text Available Urban trees sequester carbon into biomass and provide many ecosystem service benefits aboveground leading to worldwide tree planting schemes. Since soils hold ∼75% of ecosystem organic carbon, understanding the effect of urban trees on soil organic carbon (SOC and soil properties that underpin belowground ecosystem services is vital. We use an observational study to investigate effects of three important tree genera and mixed-species woodlands on soil properties (to 1 m depth compared to adjacent urban grasslands. Aboveground biomass and belowground ecosystem service provision by urban trees are found not to be directly coupled. Indeed, SOC enhancement relative to urban grasslands is genus-specific being highest under Fraxinus excelsior and Acer spp., but similar to grasslands under Quercus robur and mixed woodland. Tree cover type does not influence soil bulk density or C∶N ratio, properties which indicate the ability of soils to provide regulating ecosystem services such as nutrient cycling and flood mitigation. The trends observed in this study suggest that genus selection is important to maximise long-term SOC storage under urban trees, but emerging threats from genus-specific pathogens must also be considered.

  7. Soil carbon estimation from eucalyptus grandis using canopy spectra

    African Journals Online (AJOL)

    Michael Gebreslasie

    He et al. 2014). Spectroscopy ... soil carbon under vegetated areas, can result in an innovative and operational approach, given the ..... Gomez C, Viscarra-Rossel RA, and McBratney AB 2008, 'Soil organic carbon prediction by hyperspectral.

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

    Science.gov (United States)

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

    2012-04-01

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

  9. Carbon Cycling in Wetland Forest Soils

    Science.gov (United States)

    Carl C. Trettin; Martin F. Jurgensen

    2003-01-01

    Wetlands comprise a small proportion (i.e., 2 to 3%) of earth's terrestrial surface, yet they contain a significant proportion of the terrestrial carbon (C) pool. Soils comprise the largest terrestrial C pool (ca. 1550 Pg C in upper 100 cm; Eswaran et al., 1993; Batjes, 1996), and wetlands contain the single largest component, with estimates ranging between 18...

  10. Decadally cycling soil carbon is more sensitive to warming than faster-cycling soil carbon.

    Science.gov (United States)

    Lin, Junjie; Zhu, Biao; Cheng, Weixin

    2015-12-01

    The response of soil organic carbon (SOC) pools to globally rising surface temperature crucially determines the feedback between climate change and the global carbon cycle. However, there is a lack of studies investigating the temperature sensitivity of decomposition for decadally cycling SOC which is the main component of total soil carbon stock and the most relevant to global change. We tackled this issue using two decadally (13) C-labeled soils and a much improved measuring system in a long-term incubation experiment. Results indicated that the temperature sensitivity of decomposition for decadally cycling SOC (>23 years in one soil and >55 years in the other soil) was significantly greater than that for faster-cycling SOC (will likely make this large SOC stock vulnerable to loss by global warming in the 21st century and beyond. © 2015 John Wiley & Sons Ltd.

  11. Soil carbon pools in different pasture systems

    Directory of Open Access Journals (Sweden)

    Francisco M. Cardozo, Jr.

    2016-03-01

    Full Text Available The aim of this study was to assess the carbon pools of a tropical soil where the native forest was replaced with different pasture systems. We studied five pasture production systems, including four monoculture systems with forage grasses such as Andropogon, Brachiaria, Panicum, and Cynodon, and an agroforestry system as well as a native vegetation plot. Greater availability of fulvic acid was detected in the agroforestry system as compared with that in the other systems. Higher lability of C was detected in the Andropogon system during the dry and rainy seasons and during the dry season in Cynodon. During the dry season, all pastures systems showed deficits in the net removal of atmospheric CO2. The structure and practices of the agroforestry system enables more carbon to be sequestered in the soil as compared with the monoculture pasture, suggesting that it is an important practice to mitigate climatic change and to improve soil quality.

  12. Dynamics of carbon 14 in soils: a review

    International Nuclear Information System (INIS)

    Tamponnet, C.

    2004-01-01

    In terrestrial ecosystems, soil is the main interface between atmosphere, hydrosphere, lithosphere and biosphere. Its interactions with carbon cycle are primordial. Information about carbon 14 dynamics in soils is quite dispersed and an up-to-date status is therefore presented in this paper. Carbon 14 dynamics in soils are governed by physical processes (soil structure, soil aggregation, soil erosion) chemical processes (sequestration by soil components either mineral or organic), and soil biological processes (soil microbes, soil fauna, soil biochemistry). The relative importance of such processes varied remarkably among the various biomes (tropical forest, temperate forest, boreal forest, tropical savannah, temperate pastures, deserts, tundra, marshlands, agro ecosystems) encountered in the terrestrial eco-sphere. Moreover, application for a simplified modelling of carbon 14 dynamics in soils is proposed. (author)

  13. In-situ soil carbon analysis using inelastic neutron scattering

    Science.gov (United States)

    In situ soil carbon analysis using inelastic neutron scattering (INS) is based on the emission of 4.43 MeV gamma rays from carbon nuclei excited by fast neutrons. This in-situ method has excellent potential for easily measuring soil carbon since it does not require soil core sampling and processing ...

  14. Plant functional traits and soil carbon sequestration in contrasting biomes.

    NARCIS (Netherlands)

    De Deyn, G.B.; Cornelissen, J.H.C.; Bardgett, R.D.

    2008-01-01

    Plant functional traits control a variety of terrestrial ecosystem processes, including soil carbon storage which is a key component of the global carbon cycle. Plant traits regulate net soil carbon storage by controlling carbon assimilation, its transfer and storage in belowground biomass, and its

  15. Soil carbon sequestration and forest management: challenges and opportunities

    Science.gov (United States)

    Coeli M. Hoover

    2003-01-01

    The subject of the effects of forest management activities on soil carbon is a difficult one to address, but ongoing discussions of carbon sequestration as an emissions offset and the emergence of carbon-credit-trading systems necessitate that we broaden and deepen our understanding of the response of forest-soil carbon pools to forest management. There have been...

  16. Nexus Thinking on Soil Carbon Dynamics and Soil Health

    Science.gov (United States)

    Lal, R.

    2016-12-01

    Anthropocene is driven by global population of 7.5 billion in 2016, increasing annually by 80 million and projected to be 9.7 billion by 2050. The ecological impact (I=PAT, where P is population, A is affluence, and T is technology) of the population is similar to that of a geological force. Thus, humanity's impact is driven by demands for food, water, energy, and services derived from soil. Soil health, its capacity to function as a vital living system, is determined by quantity and quality of soil organic carbon (SOC) in the root zone ( 50cm). Maintenance of SOC at above the threshold level (1.5 to 2.0% by weight in the root zone) is critical to performing numerous ecosystem services for human wellbeing and nature conservancy. These services and functions strongly depend on nexus or inter-connectivity of biological processes within the pedosphere. The nexus is strongly governed by coupled biogeochemical cycling of water (H2O), carbon (C), nitrogen (N), phosphorus (P) and sulfur (S). Further, it is the nexus between pedological and biological processes that renews and purifies water by denaturing and filtering pollutants; circulates C among biotic and abiotic pools in close association with other elements (N, P, S); provides habitat and energy source for soil biota (macro, meso, and micro flora and fauna), facilitates exchanges of gases between soil and the atmosphere and moderates climate, and creates favorable rhizospheric processes that promote plant growth and enhance net primary productivity. Soil health, governed by SOC quality and quantity, determines the provisioning of numerous ecosystem services and the importance of nexus thinking is highlighted by the truism that "health of soil, plants, animals, human and ecosystem is one and indivisible." The sequestration of SOC depends on land use and soil management strategies which create a positive C budget. Thus, input of biomass-C into the soil must exceed the losses by erosion, mineralization and leaching

  17. Carbon depth distributions for lunar soil breccias

    International Nuclear Information System (INIS)

    Spear, R.H.

    1978-01-01

    A technique is described which permits determination of the depth distribution of carbon within the first few microns of the surfaces of lunar samples. It is based upon measurement of the energy spectrum of protons from the reaction 12 C(d,p 0 ) 13 C at a bombarding energy of 1.07 MeV. Results are presented for soil breccias from the Apollo 11, 16 and 17 missions, and for a soil sample from the Apollo 14 mission. The Apollo 16 (highland) samples show surface concentrations which ae systematically lower than those for the mare samples

  18. [Responses of forest soil carbon pool and carbon cycle to the changes of carbon input].

    Science.gov (United States)

    Wang, Qing-kui

    2011-04-01

    Litters and plant roots are the main sources of forest soil organic carbon (C). This paper summarized the effects of the changes in C input on the forest soil C pool and C cycle, and analyzed the effects of these changes on the total soil C, microbial biomass C, dissoluble organic C, and soil respiration. Different forests in different regions had inconsistent responses to C input change, and the effects of litter removal or addition and of root exclusion or not differed with tree species and regions. Current researches mainly focused on soil respiration and C pool fractions, and scarce were about the effects of C input change on the changes of soil carbon structure and stability as well as the response mechanisms of soil organisms especially soil fauna, which should be strengthened in the future.

  19. Adopting soil organic carbon management practices in soils of varying quality

    NARCIS (Netherlands)

    Merante, Paolo; Dibari, Camilla; Ferrise, Roberto; Sánchez, Berta; Iglesias, Ana; Lesschen, Jan Peter; Kuikman, Peter; Yeluripati, Jagadeesh; Smith, Pete; Bindi, Marco

    2017-01-01

    Soil organic carbon (SOC) content can greatly affect soil quality by determining and maintaining important soil physical conditions, properties and soil functions. Management practices that maintain or enhance SOC affect soil quality and may favour the capacity of soils to sequester further

  20. Edaphic controls on soil organic carbon stocks in restored grasslands

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, Sarah L.; Jastrow, Julie D.; Grimley, David A.; Gonzalez-Meler, Miquel A.

    2015-08-01

    Cultivation of undisturbed soils dramatically depletes organic carbon stocks at shallow depths, releasing a substantial quantity of stored carbon to the atmosphere. Restoration of native ecosystems can help degraded soils rebuild a portion of the depleted soil organic matter. However, the rate and magnitude of soil carbon accrual can be highly variable from site to site. Thus, a better understanding of the mechanisms controlling soil organic carbon stocks is necessary to improve predictions of soil carbon recovery. We measured soil organic carbon stocks and a suite of edaphic factors in the upper 10 cm of a series of restored tallgrass prairies representing a range of drainage conditions. Our findings suggest that factors related to soil organic matter stabilization mechanisms (texture, polyvalent cations) were key predictors of soil organic carbon, along with variables that influence plant and microbial biomass (available phosphorus, pH) and soil moisture. Exchangeable soil calcium was the strongest single predictor, explaining 74% of the variation in soil organic carbon, followed by clay content,which explained 52% of the variation. Our results demonstrate that the cumulative effects of even relatively small differences in these edaphic properties can have a large impact on soil carbon stocks when integrated over several decades.

  1. Quantifying global soil carbon losses in response to warming

    OpenAIRE

    Crowther, T. W.; Todd-Brown, K. E. O.; Rowe, C. W.; Wieder, W. R.; Carey, J. C.; Machmuller, M. B.; Snoek, B. L.; Fang, S.; Zhou, G.; Allison, S. D.; Blair, J. M.; Bridgham, S. D.; Burton, A. J.; Carrillo, Y.; Reich, P. B.

    2016-01-01

    © 2016 Macmillan Publishers Limited. All rights reserved. The majority of the Earth's terrestrial carbon is stored in the soil. If anthropogenic warming stimulates the loss of this carbon to the atmosphere, it could drive further planetary warming. Despite evidence that warming enhances carbon fluxes to and from the soil, the net global balance between these responses remains uncertain. Here we present a comprehensive analysis of warming-induced changes in soil carbon stocks by assembling dat...

  2. Carbon sequestration potential of soils in southeast Germany derived from stable soil organic carbon saturation.

    Science.gov (United States)

    Wiesmeier, Martin; Hübner, Rico; Spörlein, Peter; Geuß, Uwe; Hangen, Edzard; Reischl, Arthur; Schilling, Bernd; von Lützow, Margit; Kögel-Knabner, Ingrid

    2014-02-01

    Sequestration of atmospheric carbon (C) in soils through improved management of forest and agricultural land is considered to have high potential for global CO2 mitigation. However, the potential of soils to sequester soil organic carbon (SOC) in a stable form, which is limited by the stabilization of SOC against microbial mineralization, is largely unknown. In this study, we estimated the C sequestration potential of soils in southeast Germany by calculating the potential SOC saturation of silt and clay particles according to Hassink [Plant and Soil 191 (1997) 77] on the basis of 516 soil profiles. The determination of the current SOC content of silt and clay fractions for major soil units and land uses allowed an estimation of the C saturation deficit corresponding to the long-term C sequestration potential. The results showed that cropland soils have a low level of C saturation of around 50% and could store considerable amounts of additional SOC. A relatively high C sequestration potential was also determined for grassland soils. In contrast, forest soils had a low C sequestration potential as they were almost C saturated. A high proportion of sites with a high degree of apparent oversaturation revealed that in acidic, coarse-textured soils the relation to silt and clay is not suitable to estimate the stable C saturation. A strong correlation of the C saturation deficit with temperature and precipitation allowed a spatial estimation of the C sequestration potential for Bavaria. In total, about 395 Mt CO2 -equivalents could theoretically be stored in A horizons of cultivated soils - four times the annual emission of greenhouse gases in Bavaria. Although achieving the entire estimated C storage capacity is unrealistic, improved management of cultivated land could contribute significantly to CO2 mitigation. Moreover, increasing SOC stocks have additional benefits with respect to enhanced soil fertility and agricultural productivity. © 2013 John Wiley & Sons Ltd.

  3. Linear Theory of Soil Organic Carbon Dynamics: Implications in Modeling Soil Respiration and Carbon Sequestration

    Science.gov (United States)

    Porporato, A.; Manzoni, S.; Katul, G.

    2008-12-01

    The long-term, large-scale soil organic carbon dynamics are typically described by mathematical models based on networks of linear reservoirs. Properties of these networks can be diagnosed from linear system theory (i.e. impulse-response transformations), which is seldom used in soil biogeochemistry, although it can be used to compare and test different models in the context of long-term carbon sequestration in soils. In this work, the general theory of linear impulse-response systems is briefly reviewed and linked to the theory of stochastic point processes. Two characteristic times are considered, the residence time (i.e., the time spent by a molecule in the system) and age (the time elapsed since the molecule entered the system). Both are represented through their probability density functions, which are computed explicitly as a function of model structure. Different cases are analyzed and compared, ranging from a simple individual-pool model, to feedback models involving loops (as in models of soil organic carbon-microbial interactions and physical adsorption-desorption), and to more complex networks often used to simulate in the details the soil organic carbon processes. As examples for these complex networks, the compartmental model CENTURY (Parton et al., 1987), and the continuum-quality Q-model (Agren and Bosatta, 1996) are considered. We assess the relative importance of model structural characteristics to determine the organic carbon residence time and age distributions.

  4. Cost effective tools for soil organic carbon monitoring

    Science.gov (United States)

    Shepherd, Keith; Aynekulu, Ermias

    2013-04-01

    There is increasing demand for data on soil properties at fine spatial resolution to support management and planning decisions. Measurement of soil organic carbon has attracted much interest because (i) soil organic carbon is widely cited as a useful indicator of soil condition and (ii) of the importance of soil carbon in the global carbon cycle and climate mitigation strategies. However in considering soil measurement designs there has been insufficient attention given to careful analysis of the specific decisions that the measurements are meant to support and on what measurements have high information value for decision-making. As a result, much measurement effort may be wasted or focused on the wrong variables. A cost-effective measurement is one that reduces risk in decisions and does not cost more than the societal returns to additional evidence. A key uncertainty in measuring soil carbon as a soil condition indicator is what constitutes a good or bad level of carbon on a given soil. A measure of soil organic carbon concentration may have limited value for informing management decisions without the additional information required to interpret it, and so expending further efforts on improving measurements to increase precision may then have no value to improving the decision. Measuring soil carbon stock changes for carbon trading purposes requires high levels of measurement precision but there is still large uncertainty on whether the costs of measurement exceed the benefits. Since the largest cost component in soil monitoring is often travel to the field and physically sampling soils, it is generally cost-effective to meet multiple objectives by analysing a number of properties on a soil sample. Diffuse reflectance infrared spectroscopy is playing a key role in allowing multiple soil properties to be determined rapidly and at low cost. The method provides estimation of multiple soil properties (e.g. soil carbon, texture and mineralogy) in one measurement

  5. Variations in Soil Microbial Biomass Carbon and Soil Dissolved Organic Carbon in the Re-Vegetation of Hilly Slopes with Purple Soil

    Science.gov (United States)

    Yang, Ning; Zou, Dongsheng; Yang, Manyuan; Lin, Zhonggui

    2016-01-01

    Crust restoration is increasingly being done but we lack quantitative information on soil improvements. The study aimed to elucidate the dynamics involving soil microbial biomass carbon and soil dissolved organic carbon in the re-vegetation chronosequences of a hillslope land with purple soil in Hengyang, Hunan Province. The soil can cause serious disasters with both soil erosion and seasonal drought, and also becomes a typical representative of ecological disaster area in South China. Using the space-for-time method, we selected six typical sampling plots, designated as follows: grassplot community, meadow thicket community, frutex community, frutex and arbor community, arbor community, and top-level vegetation community. These plots were established to analyze the changes in soil microbial biomass carbon, soil microbial quotien, dissolved organic carbon, dissolved organic carbon/soil organic carbon, and soil basal respiration in 0–10, 10–20, and 20–40 cm soil layers. The relationships of these parameters with soils physic-chemical properties were also determined. The ecological environment of the 6 plant communities is similar and typical; they denoted six different successive stages of restoration on hillslopes with purple soils in Hengyang, Hunan Province. The soil microbial biomass carbon and soil basal respiration contents decreased with increasing soil depth but increased with re-vegetation. By contrast, soil microbial quotient increased with increasing soil depth and re-vegetation. From 0–10 cm soil layer to 20–40 cm soil layer, the dissolved organic carbon content decreased in different re-vegetation stages. In the process of re-vegetation, the dissolved organic carbon content increased in the 0–10 and 10–20 cm soil layers, whereas the dissolved organic carbon content decreased after an initial increase in the 20–40 cm soil layers. Meanwhile, dissolved organic carbon/soil organic carbon increased with increasing soil depth but decreased

  6. Differential priming of soil carbon driven by soil depth and root impacts on carbon availability

    Energy Technology Data Exchange (ETDEWEB)

    de Graaff, Marie-Anne; Jastrow, Julie D.; Gillette, Shay; Johns, Aislinn; Wullschleger, Stan D.

    2013-11-15

    Enhanced root-exudate inputs can stimulate decomposition of soil carbon (C) by priming soil microbial activity, but the mechanisms controlling the magnitude and direction of the priming effect remain poorly understood. With this study we evaluated how differences in soil C availability affect the impact of simulated root exudate inputs on priming. We conducted a 60-day laboratory incubation with soils collected (60 cm depth) from under six switchgrass (Panicum virgatum) cultivars. Differences in specific root length (SRL) among cultivars were expected to result in small differences in soil C inputs and thereby create small differences in the availability of recent labile soil C; whereas soil depth was expected to create large overall differences in soil C availability. Soil cores from under each cultivar (roots removed) were divided into depth increments of 0–10, 20–30, and 40–60 cm and incubated with addition of either: (1) water or (2) 13C-labeled synthetic root exudates (0.7 mg C/g soil). We measured CO2 respiration throughout the experiment. The natural difference in 13C signature between C3 soils and C4 plants was used to quantify cultivar-induced differences in soil C availability. Amendment with 13C-labeled synthetic root-exudate enabled evaluation of SOC priming. Our experiment produced three main results: (1) switchgrass cultivars differentially influenced soil C availability across the soil profile; (2) small differences in soil C availability derived from recent root C inputs did not affect the impact of exudate-C additions on priming; but (3) priming was greater in soils from shallow depths (relatively high total soil C and high ratio of labile-to-stable C) compared to soils from deep depths (relatively low total soil C and low ratio of labile-to-stable C). These findings suggest that the magnitude of the priming effect is affected, in part, by the ratio of root exudate C inputs to total soil C and that the impact of changes in exudate inputs on

  7. Soil carbon estimation from eucalyptus grandis using canopy spectra

    African Journals Online (AJOL)

    Mapping soil fertility parameters, such as soil carbon (C), is fundamentally important for forest management and research related to forest growth and climate change. This study seeks to establish the link between Eucalyptus grandis canopy spectra and soil carbon using raw and continuum-removed spectra. Canopy-level ...

  8. Anaerobic microsites have an unaccounted role in soil carbon stabilization.

    Science.gov (United States)

    Keiluweit, Marco; Wanzek, Tom; Kleber, Markus; Nico, Peter; Fendorf, Scott

    2017-11-24

    Soils represent the largest carbon reservoir within terrestrial ecosystems. The mechanisms controlling the amount of carbon stored and its feedback to the climate system, however, remain poorly resolved. Global carbon models assume that carbon cycling in upland soils is entirely driven by aerobic respiration; the impact of anaerobic microsites prevalent even within well-drained soils is missed within this conception. Here, we show that anaerobic microsites are important regulators of soil carbon persistence, shifting microbial metabolism to less efficient anaerobic respiration, and selectively protecting otherwise bioavailable, reduced organic compounds such as lipids and waxes from decomposition. Further, shifting from anaerobic to aerobic conditions leads to a 10-fold increase in volume-specific mineralization rate, illustrating the sensitivity of anaerobically protected carbon to disturbance. The vulnerability of anaerobically protected carbon to future climate or land use change thus constitutes a yet unrecognized soil carbon-climate feedback that should be incorporated into terrestrial ecosystem models.

  9. Microbial carbon recycling: an underestimated process controlling soil carbon dynamics

    Science.gov (United States)

    Basler, A.; Dippold, M.; Helfrich, M.; Dyckmans, J.

    2015-07-01

    The mean residence times (MRT) of different compound classes of soil organic matter (SOM) do not match their inherent recalcitrance to decomposition. One reason for this is the stabilisation within the soil matrix, but recycling, i.e. the reuse of "old" organic material to form new biomass may also play a role as it uncouples the residence times of organic matter from the lifetime of discrete molecules in soil. We analysed soil sugar dynamics in a natural 30 years old labelling experiment after a~wheat-maize vegetation change to determine the extent of recycling and stabilisation in plant and microbial derived sugars: while plant derived sugars are only affected by stabilisation processes, microbial sugars may be subject to both, stabilisation and recycling. To disentangle the dynamics of soil sugars, we separated different density fractions (free particulate organic matter (fPOM), light occluded particulate organic matter (≤1.6 g cm-3; oPOM1.6), dense occluded particulate organic matter (≤2 g cm-3; oPOM2) and mineral-associated organic matter (>2 g cm-3; Mineral)) of a~silty loam under long term wheat and maize cultivation. The isotopic signature of sugars was measured by high pressure liquid chromatography coupled to isotope ratio mass spectrometry (HPLC/IRMS), after hydrolysis with 4 M Trifluoroacetic acid (TFA). While apparent mean residence times (MRT) of sugars were comparable to total organic carbon in the bulk soil and mineral fraction, the apparent MRT of sugars in the oPOM fractions were considerably lower than those of the total carbon of these fractions. This indicates that oPOM formation was fuelled by microbial activity feeding on new plant input. In the bulk soil, mean residence times of the mainly plant derived xylose (xyl) were significantly lower than those of mainly microbial derived sugars like galactose (gal), rhamnose (rha), fucose (fuc), indicating that recycling of organic matter is an important factor regulating organic matter dynamics

  10. Quantifying global soil carbon losses in response to warming

    NARCIS (Netherlands)

    Crowther, T W; Todd-Brown, K E O; Rowe, C W; Wieder, W R; Carey, J C; Machmuller, M B; Snoek, B L; Fang, S; Zhou, G; Allison, S D; Blair, J M; Bridgham, S D; Burton, A J; Carrillo, Y; Reich, P B; Clark, J S; Classen, A T; Dijkstra, F A; Elberling, B; Emmett, B A; Estiarte, M; Frey, S D; Guo, J; Harte, J; Jiang, L; Johnson, B R; Kröel-Dulay, G; Larsen, K S; Laudon, H; Lavallee, J M; Lupascu, M; Ma, L N; Marhan, S; Michelsen, A; Mohan, J; Niu, S; Pendall, E; Peñuelas, J; Pfeifer-Meister, L; Poll, C; Reinsch, S; Reynolds, L L; Schmidt, I K; Sistla, S; Sokol, N W; Templer, P H; Treseder, K K; Welker, J M; Bradford, M A

    2016-01-01

    The majority of the Earth's terrestrial carbon is stored in the soil. If anthropogenic warming stimulates the loss of this carbon to the atmosphere, it could drive further planetary warming. Despite evidence that warming enhances carbon fluxes to and from the soil, the net global balance between

  11. Quantifying global soil carbon losses in response to warming

    NARCIS (Netherlands)

    Crowther, T.W.; Todd-Brown, K.E.O.; Rowe, C.W.; Wieder, W.R.; Carey, J.C.; Machmuller, M.B.; Snoek, B.L.; Fang, S.; Zhou, G.; Allison, S.D.; Blair, J.M.; Bridgham, S.D.; Burton, A.J.; Carrillo, Y.; Reich, P.B.; Clark, J.S.; Classen, A.T.; Dijkstra, F.A.; Elberling, B.; Emmett, B.A.; Estiarte, M.; Frey, S.D.; Guo, J.; Harte, J.; Jiang, L.; Johnson, B.R.; Kröel-Dulay, G.; Larsen, K.S.; Laudon, H.; Lavallee, J.M.; Luo, Y.; Lupascu, M.; Ma, L.N.; Marhan, S.; Michelsen, A.; Mohan, J.; Niu, S.; Pendall, E.; Peñuelas, J.; Pfeifer-Meister, L.; Poll, C.; Reinsch, S.; Reynolds, L.L.; Schmidt, I.K.; Sistla, S.; Sokol, N.W.; Templer, P.H.; Treseder, K.K.; Welker, J.M.; Bradford, M.A.

    2016-01-01

    The majority of the Earth’s terrestrial carbon is stored in the soil. If anthropogenic warming stimulates the loss of this carbon to the atmosphere, it could drive further planetary warming. Despite evidence that warming enhances carbon fluxes to and from the soil the net global balance between

  12. Quantifying global soil carbon losses in response to warming

    NARCIS (Netherlands)

    Crowther, T. W.; Todd-Brown, K. E. O.; Rowe, C. W.; Wieder, W. R.; Carey, J. C.; Machmuller, M. B.; Snoek, B. L.; Fang, S.; Zhou, G.; Allison, S. D.; Blair, J. M.; Bridgham, S. D.; Burton, A. J.; Carrillo, Y.; Reich, P. B.; Clark, J. S.; Classen, A. T.; Dijkstra, F. A.; Elberling, B.; Emmett, B. A.; Estiarte, M.; Frey, S. D.; Guo, J.; Harte, J.; Jiang, L.; Johnson, B. R.; Kröel-Dulay, G.; Larsen, K. S.; Laudon, H.; Lavallee, J. M.; Luo, Y.; Lupascu, M.; Ma, L. N.; Marhan, S.; Michelsen, A.; Mohan, J.; Niu, S.; Pendall, E.; Peñuelas, J.; Pfeifer-Meister, L.; Poll, C.; Reinsch, S.; Reynolds, L. L.; Schmidt, I. K.; Sistla, S.; Sokol, N. W.; Templer, P. H.; Treseder, K. K.; Welker, J. M.; Bradford, M. A.

    2016-01-01

    The majority of the Earth’s terrestrial carbon is stored in the soil. If anthropogenic warming stimulates the loss of this carbon to the atmosphere, it could drive further planetary warming1, 2, 3, 4. Despite evidence that warming enhances carbon fluxes to and from the soil5, 6, the net global

  13. Managing uncertainty in soil carbon feedbacks to climate change

    NARCIS (Netherlands)

    Bradford, M.A.; Wieder, W.R.; Bonan, G.B.; Fierer, N.; Raymond, P.A.; Crowther, Thomas W.

    2016-01-01

    Planetary warming may be exacerbated if it accelerates loss of soil carbon to the atmosphere. This carbon-cycle–climate feedback is included in climate projections. Yet, despite ancillary data supporting a positive feedback, there is limited evidence for soil carbon loss under warming. The low

  14. Quantifying global soil carbon losses in response to warming

    Science.gov (United States)

    Crowther, T. W.; Todd-Brown, K. E. O.; Rowe, C. W.; Wieder, W. R.; Carey, J. C.; Machmuller, M. B.; Snoek, B. L.; Fang, S.; Zhou, G.; Allison, S. D.; Blair, J. M.; Bridgham, S. D.; Burton, A. J.; Carrillo, Y.; Reich, P. B.; Clark, J. S.; Classen, A. T.; Dijkstra, F. A.; Elberling, B.; Emmett, B. A.; Estiarte, M.; Frey, S. D.; Guo, J.; Harte, J.; Jiang, L.; Johnson, B. R.; Kröel-Dulay, G.; Larsen, K. S.; Laudon, H.; Lavallee, J. M.; Luo, Y.; Lupascu, M.; Ma, L. N.; Marhan, S.; Michelsen, A.; Mohan, J.; Niu, S.; Pendall, E.; Peñuelas, J.; Pfeifer-Meister, L.; Poll, C.; Reinsch, S.; Reynolds, L. L.; Schmidt, I. K.; Sistla, S.; Sokol, N. W.; Templer, P. H.; Treseder, K. K.; Welker, J. M.; Bradford, M. A.

    2016-12-01

    The majority of the Earth’s terrestrial carbon is stored in the soil. If anthropogenic warming stimulates the loss of this carbon to the atmosphere, it could drive further planetary warming. Despite evidence that warming enhances carbon fluxes to and from the soil, the net global balance between these responses remains uncertain. Here we present a comprehensive analysis of warming-induced changes in soil carbon stocks by assembling data from 49 field experiments located across North America, Europe and Asia. We find that the effects of warming are contingent on the size of the initial soil carbon stock, with considerable losses occurring in high-latitude areas. By extrapolating this empirical relationship to the global scale, we provide estimates of soil carbon sensitivity to warming that may help to constrain Earth system model projections. Our empirical relationship suggests that global soil carbon stocks in the upper soil horizons will fall by 30 ± 30 petagrams of carbon to 203 ± 161 petagrams of carbon under one degree of warming, depending on the rate at which the effects of warming are realized. Under the conservative assumption that the response of soil carbon to warming occurs within a year, a business-as-usual climate scenario would drive the loss of 55 ± 50 petagrams of carbon from the upper soil horizons by 2050. This value is around 12-17 per cent of the expected anthropogenic emissions over this period. Despite the considerable uncertainty in our estimates, the direction of the global soil carbon response is consistent across all scenarios. This provides strong empirical support for the idea that rising temperatures will stimulate the net loss of soil carbon to the atmosphere, driving a positive land carbon-climate feedback that could accelerate climate change.

  15. Quantifying global soil carbon losses in response to warming.

    Science.gov (United States)

    Crowther, T W; Todd-Brown, K E O; Rowe, C W; Wieder, W R; Carey, J C; Machmuller, M B; Snoek, B L; Fang, S; Zhou, G; Allison, S D; Blair, J M; Bridgham, S D; Burton, A J; Carrillo, Y; Reich, P B; Clark, J S; Classen, A T; Dijkstra, F A; Elberling, B; Emmett, B A; Estiarte, M; Frey, S D; Guo, J; Harte, J; Jiang, L; Johnson, B R; Kröel-Dulay, G; Larsen, K S; Laudon, H; Lavallee, J M; Luo, Y; Lupascu, M; Ma, L N; Marhan, S; Michelsen, A; Mohan, J; Niu, S; Pendall, E; Peñuelas, J; Pfeifer-Meister, L; Poll, C; Reinsch, S; Reynolds, L L; Schmidt, I K; Sistla, S; Sokol, N W; Templer, P H; Treseder, K K; Welker, J M; Bradford, M A

    2016-11-30

    The majority of the Earth's terrestrial carbon is stored in the soil. If anthropogenic warming stimulates the loss of this carbon to the atmosphere, it could drive further planetary warming. Despite evidence that warming enhances carbon fluxes to and from the soil, the net global balance between these responses remains uncertain. Here we present a comprehensive analysis of warming-induced changes in soil carbon stocks by assembling data from 49 field experiments located across North America, Europe and Asia. We find that the effects of warming are contingent on the size of the initial soil carbon stock, with considerable losses occurring in high-latitude areas. By extrapolating this empirical relationship to the global scale, we provide estimates of soil carbon sensitivity to warming that may help to constrain Earth system model projections. Our empirical relationship suggests that global soil carbon stocks in the upper soil horizons will fall by 30 ± 30 petagrams of carbon to 203 ± 161 petagrams of carbon under one degree of warming, depending on the rate at which the effects of warming are realized. Under the conservative assumption that the response of soil carbon to warming occurs within a year, a business-as-usual climate scenario would drive the loss of 55 ± 50 petagrams of carbon from the upper soil horizons by 2050. This value is around 12-17 per cent of the expected anthropogenic emissions over this period. Despite the considerable uncertainty in our estimates, the direction of the global soil carbon response is consistent across all scenarios. This provides strong empirical support for the idea that rising temperatures will stimulate the net loss of soil carbon to the atmosphere, driving a positive land carbon-climate feedback that could accelerate climate change.

  16. Monitoring of soil organic carbon and nitrogen stocks in different ...

    African Journals Online (AJOL)

    Soil organic carbon (SOC) and soil nitrogen (SN) are the principal components in soil quality assessment, and in mitigation the global greenhouse effect. In Iran, little information exists on the stocks of SOC and SN. SOC and SN stocks are a function of the SOC and SN concentrations and the bulk density of the soil that are ...

  17. 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

  18. Soil organic carbon in eastern Australia

    Science.gov (United States)

    Hobley, E.; Baldock, J.; Hua, Q.; Wilson, B.

    2016-12-01

    We investigated the drivers of SOC dynamics and depth distribution across eastern Australia using laboratory analyses (CN, fractionation, radiocarbon) coupled with modelling and machine learning. At over 1400 sites, surface SOC storage was driven by precipitation, whereas SOC depth distribution (0-30 cm) was influenced by land-use. Based upon these findings, 100 sites were selected for profile analysis (up to 1 m) of SOC and its component fractions - particulate (POC), humus (HOC) and resistant (ROC) organic carbon. Profile SOC content was modelled using an exponential model describing surface SOC content, SOC depth distribution and residual SOC at depth and the drivers of these parameters investigated via machine learning. Corroborating previous findings, surface SOC content was highly influenced by rainfall, whereas SOC depth distribution was influenced by land-use. At depth, site properties were the most important predictors of SOC. Cropped sites had significantly lower SOC content than native and grazed sites at depth, indicating that land-use influences SOC content throughout the profile. The machine learning algorithms identified depth as the key control on the proportion of all three fractions down the profile: POC decreased whereas HOC increased with increasing depth. POC was strongly linked with total SOC but HOC and ROC were driven more by climate and soil physico-chemical properties. Human influences (land-use and management) were not important to the fractions, implying that the controls humans can exert on SOC stability may be limited. A subset of 12 soil profiles was analysed for 14C. Radiocarbon content was affected strongly by land-use, with effects most pronounced at depth. Native systems had the youngest carbon down the profile, cropped systems had the oldest SOC. All fractions reacted to land-use change down the soil profile, indicating a lack of stability when the whole profile is viewed. These results indicate that natural systems act as a

  19. Modelling soil organic carbon concentration of mineral soils in arable lands using legacy soil data

    DEFF Research Database (Denmark)

    Suuster, E; Ritz, Christian; Roostalu, H

    2012-01-01

    as to the advantages and shortcomings of the different commonly used prediction methods. Therefore, we compared and evaluated the merits of the median approach, analysis of covariance, mixed models and random forests in the context of prediction of SOC concentrations of mineral soils under arable management in the A......Soil organic carbon (SOC) concentration is an essential factor in biomass production and soil functioning. SOC concentration values are often obtained by prediction but the prediction accuracy depends much on the method used. Currently, there is a lack of evidence in the soil science literature......-horizon. Three soil properties were used in all of the developed models: soil type, physical clay content (particle size

  20. Legacy effects of grassland management on soil carbon to depth.

    Science.gov (United States)

    Ward, Susan E; Smart, Simon M; Quirk, Helen; Tallowin, Jerry R B; Mortimer, Simon R; Shiel, Robert S; Wilby, Andrew; Bardgett, Richard D

    2016-08-01

    The importance of managing land to optimize carbon sequestration for climate change mitigation is widely recognized, with grasslands being identified as having the potential to sequester additional carbon. However, most soil carbon inventories only consider surface soils, and most large-scale surveys group ecosystems into broad habitats without considering management intensity. Consequently, little is known about the quantity of deep soil carbon and its sensitivity to management. From a nationwide survey of grassland soils to 1 m depth, we show that carbon in grassland soils is vulnerable to management and that these management effects can be detected to considerable depth down the soil profile, albeit at decreasing significance with depth. Carbon concentrations in soil decreased as management intensity increased, but greatest soil carbon stocks (accounting for bulk density differences), were at intermediate levels of management. Our study also highlights the considerable amounts of carbon in subsurface soil below 30 cm, which is missed by standard carbon inventories. We estimate grassland soil carbon in Great Britain to be 2097 Tg C to a depth of 1 m, with ~60% of this carbon being below 30 cm. Total stocks of soil carbon (t ha(-1) ) to 1 m depth were 10.7% greater at intermediate relative to intensive management, which equates to 10.1 t ha(-1) in surface soils (0-30 cm), and 13.7 t ha(-1) in soils from 30 to 100 cm depth. Our findings highlight the existence of substantial carbon stocks at depth in grassland soils that are sensitive to management. This is of high relevance globally, given the extent of land cover and large stocks of carbon held in temperate managed grasslands. Our findings have implications for the future management of grasslands for carbon storage and climate mitigation, and for global carbon models which do not currently account for changes in soil carbon to depth with management. © 2016 John Wiley & Sons Ltd.

  1. Reduced carbon sequestration potential of biochar in acidic soil.

    Science.gov (United States)

    Sheng, Yaqi; Zhan, Yu; Zhu, Lizhong

    2016-12-01

    Biochar application in soil has been proposed as a promising method for carbon sequestration. While factors affecting its carbon sequestration potential have been widely investigated, the number of studies on the effect of soil pH is limited. To investigate the carbon sequestration potential of biochar across a series of soil pH levels, the total carbon emission, CO 2 release from inorganic carbon, and phospholipid fatty acids (PLFAs) of six soils with various pH levels were compared after the addition of straw biochar produced at different pyrolysis temperatures. The results show that the acidic soils released more CO 2 (1.5-3.5 times higher than the control) after the application of biochar compared with neutral and alkaline soils. The degradation of both native soil organic carbon (SOC) and biochar were accelerated. More inorganic CO 2 release in acidic soil contributed to the increased degradation of biochar. Higher proportion of gram-positive bacteria in acidic soil (25%-36%) was responsible for the enhanced biochar degradation and simultaneously co-metabolism of SOC. In addition, lower substrate limitation for bacteria, indicated by higher C-O stretching after the biochar application in the acidic soil, also caused more CO 2 release. In addition to the soil pH, other factors such as clay contents and experimental duration also affected the phsico-chemical and biotic processes of SOC dynamics. Gram-negative/gram-positive bacteria ratio was found to be negatively related to priming effects, and suggested to serve as an indicator for priming effect. In general, the carbon sequestration potential of rice-straw biochar in soil reduced along with the decrease of soil pH especially in a short-term. Given wide spread of acidic soils in China, carbon sequestration potential of biochar may be overestimated without taking into account the impact of soil pH. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Effects of soil type and depth on carbon distribution within soil macroaggregates from temperate grassland systems

    NARCIS (Netherlands)

    Torres-Sallan, Gemma; Creamer, Rachel E.; Lanigan, Gary J.; Reidy, Brian; Byrne, Kenneth A.

    2018-01-01

    Grassland soils have been highlighted as a global soil carbon (C) sink, and have the potential to sequester additional C. Sequestration of C can occur through incorporation of soil organic carbon (SOC) within microaggregates and the silt and clay fractions. The distribution of SOC within

  3. 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.

  4. Patterning between urban soil color and carbon stocks

    Science.gov (United States)

    Schifman, L. A.; Herrmann, D.; Shuster, W.

    2017-12-01

    Urban soils are extensively modified compared to their non-urban counterparts. These modifications are expected to affect the vertical distribution of total soil carbon as well as its constituent pools - soil organic carbon, black carbon, and inorganic carbon. Assigning color to soil horizons using the Munsell color system is a standard field method employed by soil scientists that can also reveal generalizable information about various environmental metrics. A new dataset on urban soils and their reference counterparts that cover 11 regions in the United States and advances in quantitative pedology allowed us to construct a log-linear model that relates Value, the lightness of a color hue, to the concentration of total carbon throughout a soil column of up to 450 cm depth. Overall, the relationship between 671 points resulted in an r2 of 0.23 with a p<0.001. As expected, organic carbon, shifted values to the lower end of the scale (darker), whereas inorganic carbon increased soil color values (lighter). These findings allow for a simplified understanding of shifts in carbon pools throughout a soil profile.

  5. Deep carbon storage potential of buried floodplain soils.

    Science.gov (United States)

    D'Elia, Amanda H; Liles, Garrett C; Viers, Joshua H; Smart, David R

    2017-08-15

    Soils account for the largest terrestrial pool of carbon and have the potential for even greater quantities of carbon sequestration. Typical soil carbon (C) stocks used in global carbon models only account for the upper 1 meter of soil. Previously unaccounted for deep carbon pools (>1 m) were generally considered to provide a negligible input to total C contents and represent less dynamic C pools. Here we assess deep soil C pools associated with an alluvial floodplain ecosystem transitioning from agricultural production to restoration of native vegetation. We analyzed the soil organic carbon (SOC) concentrations of 87 surface soil samples (0-15 cm) and 23 subsurface boreholes (0-3 m). We evaluated the quantitative importance of the burial process in the sequestration of subsurface C and found our subsurface soils (0-3 m) contained considerably more C than typical C stocks of 0-1 m. This deep unaccounted soil C could have considerable implications for global C accounting. We compared differences in surface soil C related to vegetation and land use history and determined that flooding restoration could promote greater C accumulation in surface soils. We conclude deep floodplain soils may store substantial quantities of C and floodplain restoration should promote active C sequestration.

  6. Biochar for soil fertility and natural carbon sequestration

    Science.gov (United States)

    Rostad, C.E.; Rutherford, D.W.

    2011-01-01

    Biochar is charcoal (similar to chars generated by forest fires) that is made for incorporation into soils to increase soil fertility while providing natural carbon sequestration. The incorporation of biochar into soils can preserve and enrich soils and also slow the rate at which climate change is affecting our planet. Studies on biochar, such as those cited by this report, are applicable to both fire science and soil science.

  7. Modelling erosion and its interaction with soil organic carbon.

    Science.gov (United States)

    Oyesiku-Blakemore, Joseph; Verrot, Lucile; Geris, Josie; Zhang, Ganlin; Peng, Xinhua; Hallett, Paul; Smith, Jo

    2017-04-01

    Water driven soil erosion removes and relocates a significant quantity of soil organic carbon. In China the quantity of carbon removed from the soil through water erosion has been reported to be 180+/-80 Mt y-1 (Yue et al., 2011). Being able to effectively model the movement of such a large quantity of carbon is important for the assessment of soil quality and carbon storage in the region and further afield. A large selection of erosion models are available and much work has been done on evaluating the performance of these in developed countries (Merritt et al., 2006). Fewer studies have evaluated the application of these models on soils in developing countries. Here we evaluate and compare the performance of two of these models, WEPP (Laflen et al., 1997) and RUSLE (Renard et al., 1991), for simulations of soil erosion and deposition at the slope scale on a Chinese Red Soil under cultivation using measurements taken at the site. We also describe work to dynamically couple the movement of carbon presented in WEPP to a model of soil organic matter and nutrient turnover, ECOSSE (Smith et al., 2010). This aims to improve simulations of both erosion and carbon cycling by using the simulated rates of erosion to alter the distribution of soil carbon, the depth of soil and the clay content across the slopes, changing the simulated rate of carbon turnover. This, in turn, affects the soil carbon available to be eroded in the next timestep, so improving estimates of carbon erosion. We compare the simulations of this coupled modelling approach with those of the unaltered ECOSSE and WEPP models to determine the importance of coupling erosion and turnover models on the simulation of carbon losses at catchment scale.

  8. [Correlation Among Soil Organic Carbon, Soil Inorganic Carbon and the Environmental Factors in a Typical Oasis in the Southern Edge of the Tarim Basin].

    Science.gov (United States)

    Gong, Lu; Zhu, Mei-ling; Liu, Zeng-yuan; Zhang, Xue-ni; Xie, Li-na

    2016-04-15

    We analyzed the differentiation among the environmental factors and soil organic/inorganic carbon contents of irrigated desert soil, brown desert soil, saline soil and aeolian sandy soil by classical statistics methods, and studied the correlation between soil carbon contents and the environmental factor by redundancy analysis (RDA) in a typical oasis of Yutian in the southern edge of the Tarim Basin. The results showed that the average contents of soil organic carbon and soil inorganic carbon were 2.51 g · kg⁻¹ and 25.63 g · kg⁻¹ respectively. The soil organic carbon content of the irrigated desert soil was significantly higher than those of brown desert soil, saline soil and aeolian sandy soil, while the inorganic carbon content of aeolian sandy soil was significantly higher than those of other soil types. The soil moisture and nutrient content were the highest in the irrigated desert soil and the lowest in the aeolian sandy sail. All soil types had high degree of salinization except the irrigated desert soil. The RDA results showed that the impacts of environmental factors on soil carbon contents ranked in order of importance were total nitrogen > available phosphorus > soil moisture > ground water depth > available potassium > pH > total salt. The soil carbon contents correlated extremely significantly with total nitrogen, available phosphorus, soil moisture and ground water depth (P soil carbon contents and other environmental factors (P > 0.05).

  9. The Potential Of The Soil For Stabilisation Of Organic Carbon In Soil Aggregates

    Directory of Open Access Journals (Sweden)

    Tobiašová Erika

    2015-06-01

    Full Text Available Carbon stabilisation in soil is the result of interaction between the chemical and physical mechanisms of protection and the dominance of the mechanism depends not only on the long-term constant characteristics of soil but also on the properties, which can be partly influenced by human activities. In this study, the potential of the soil for stabilisation of carbon (Ps in different soil types depending on soil properties was compared. Experiment included six soils (Eutric Fluvisol, Mollic Fluvisol, Haplic Chernozem, Haplic Luvisol, Eutric Cambisol, and Rendzic Leptosol of different land uses (forest, meadow, urban, and agro-ecosystem in Slovakia. Ps was determined with dependence on the ratio of labile and stable fractions of carbon in the soil macro-aggregates. Ps was in an exponential dependence (r = 0.942; P < 0.01 with production potential of the soil, and the fractions of dry-sieved aggregates larger than 3 mm play an important role in the first stages of the carbon stabilisation. The suitable parameter, which reflects the changes in carbon stability in the soil is the ratio of the labile carbon and non-labile carbon in the soil macro-aggregates (L/NL. Lower values of L/NL that indicate a higher stability of carbon were determined at a higher pH, at the higher content of carbonates and exchangeable basic cations, and at a higherportion of humic acids free and bound with mobile sesquioxides R2O3.

  10. Effects of strip and full-width tillage on soil carbon IV oxide-carbon ...

    African Journals Online (AJOL)

    Yomi

    carbon IV oxide-carbon (CO2-C) fluxes, bacterial and fungal populations in growing period of sunflower. (Helianthus annus). A row-crop .... Tillage accelerates soil CO2 emission by improving soil aeration, disaggregating soil .... Schleibler calcimeter (Tee et al., 1993), total nitrogen (N) was determined by using the micro ...

  11. Isotopic studies of Yucca Mountain soil fluids and carbonate pedogenesis

    International Nuclear Information System (INIS)

    McConnaughey, T.A.; Whelan, J.F.; Wickland, K.P.; Moscati, R.J.

    1994-01-01

    Secondary carbonates occurring within the soils, faults, and subsurface fractures of Yucca Mountain contain some of the best available records of paleoclimate and palehydrology for the potential radioactive waste repository site. This article discusses conceptual and analytical advances being made with regard to the interpretation of stable isotope data from pedogenic carbonates, specifically related to the 13 C content of soil CO 2 , CaCO 3 , precipitation mechanisms, and isotopic fractionations between parent fluids and precipitating carbonates. The 13 C content of soil carbon dioxide from Yucca Mountain and vicinity shows most of the usual patterns expected in such contexts: Decreasing 13 C content with depth decreasing 13 C with altitude and reduced 13 C during spring. These patterns exist within the domain of a noisy data set; soil and vegetational heterogeneities, weather, and other factors apparently contribute to isotopic variability in the system. Several soil calcification mechanisms appear to be important, involving characteristic physical and chemical environments and isotopic fractionations. When CO 2 loss from thin soil solutions is an important driving factor, carbonates may contain excess heavy isotopes, compared to equilibrium precipitation with soil fluids. When root calcification serves as a proton generator for plant absorption of soil nutrients, heavy isotope deficiencies are likely. Successive cycles of dissolution and reprecipitation mix and redistribute pedogenic carbonates, and tend to isotopically homogenize and equilibrate pedogenic carbonates with soil fluids

  12. The uncertainty of modeled soil carbon stock change for Finland

    Science.gov (United States)

    Lehtonen, Aleksi; Heikkinen, Juha

    2013-04-01

    Countries should report soil carbon stock changes of forests for Kyoto Protocol. Under Kyoto Protocol one can omit reporting of a carbon pool by verifying that the pool is not a source of carbon, which is especially tempting for the soil pool. However, verifying that soils of a nation are not a source of carbon in given year seems to be nearly impossible. The Yasso07 model was parametrized against various decomposition data using MCMC method. Soil carbon change in Finland between 1972 and 2011 were simulated with Yasso07 model using litter input data derived from the National Forest Inventory (NFI) and fellings time series. The uncertainties of biomass models, litter turnoverrates, NFI sampling and Yasso07 model were propagated with Monte Carlo simulations. Due to biomass estimation methods, uncertainties of various litter input sources (e.g. living trees, natural mortality and fellings) correlate strongly between each other. We show how original covariance matrices can be analytically combined and the amount of simulated components reduce greatly. While doing simulations we found that proper handling correlations may be even more essential than accurate estimates of standard errors. As a preliminary results, from the analysis we found that both Southern- and Northern Finland were soil carbon sinks, coefficient of variations (CV) varying 10%-25% when model was driven with long term constant weather data. When we applied annual weather data, soils were both sinks and sources of carbon and CVs varied from 10%-90%. This implies that the success of soil carbon sink verification depends on the weather data applied with models. Due to this fact IPCC should provide clear guidance for the weather data applied with soil carbon models and also for soil carbon sink verification. In the UNFCCC reporting carbon sinks of forest biomass have been typically averaged for five years - similar period for soil model weather data would be logical.

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

    Czech Academy of Sciences Publication Activity Database

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

    2012-01-01

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

  14. Soil Carbon Characteristics of a Fluvisol Affected by Aggregates ...

    African Journals Online (AJOL)

    Michael Horsfall

    105 – 111. Blom, L.and Eddhausen, L. (1985). Direct titration of carbon dioxide. Analytical Chemistry 13: 120 –. 128. Boyle, M., and Paul, E. A. (1989). Carbon and nitrogen kinetics in soil prevcously amended with sewage sludge. Soil Science Society America. Journal 53:99 – 103. Cambardella, C. A.and Elliott, E. T. (1992).

  15. Soil organic carbon enrichment of dust emissions: Magnitude, mechanisms and its implications for the carbon cycle

    Science.gov (United States)

    Soil erosion is an important component of the global carbon cycle. However, little attention has been given to the role of aeolian processes in influencing soil organic carbon (SOC) flux and the release of greenhouse gasses, such as carbon-dioxide (CO2), to the atmosphere. Understanding the magnitu...

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

    Directory of Open Access Journals (Sweden)

    Ewa Błońska

    2017-11-01

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

  17. GlobalSoilMap and Global Carbon Predictions

    DEFF Research Database (Denmark)

    Hempel, Jonathan; McBratney, Alex B.; Arrouays, Dominique

    The GlobalSoilMap project is representative of a global consortium of scientific institutions involved in soil survey and soil science. The GlobalSoilMap group was formed as an outgrowth of the International Union of Soil Sciences Working Group for Digital Soil Mapping with the purpose of providing...... consistently produced soil property information at 100 m resolution across the world. This information will aid in solving some of the key environment and societal issues of the day, including food security, global climate change land degradation and carbon sequestration. Data would be produced using mostly...

  18. Carbon Stock Stratification of Peat Soils in South Kalimantan, Indonesia

    OpenAIRE

    Siti Nurzakiah; Muhammad Noor; Dedi Nursyamsi

    2015-01-01

    Carbon stock in peat soils is very high, it is necessary to prudent in its management because peat soils is emitting greenhouse gases such as CO2 during land clearing due to oxidation of peat layer.  This research was conducted to study soil carbon stock stratification in relation to soil physical and chemical properties. The carbon stock stratification was based on maturity degrees of peat.  The study was conducted in Pulau Damar Village, Hulu Sungai Utara District, South Kalimantan Province...

  19. [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.

  20. Contribution of permafrost soils to the global carbon budget

    International Nuclear Information System (INIS)

    Schaphoff, Sibyll; Heyder, Ursula; Ostberg, Sebastian; Gerten, Dieter; Heinke, Jens; Lucht, Wolfgang

    2013-01-01

    Climate warming affects permafrost soil carbon pools in two opposing ways: enhanced vegetation growth leads to higher carbon inputs to the soil, whereas permafrost melting accelerates decomposition and hence carbon release. Here, we study the spatial and temporal dynamics of these two processes under scenarios of climate change and evaluate their influence on the carbon balance of the permafrost zone. We use the dynamic global vegetation model LPJmL, which simulates plant physiological and ecological processes and includes a newly developed discrete layer energy balance permafrost module and a vertical carbon distribution within the soil layer. The model is able to reproduce the interactions between vegetation and soil carbon dynamics as well as to simulate dynamic permafrost changes resulting from changes in the climate. We find that vegetation responds more rapidly to warming of the permafrost zone than soil carbon pools due to long time lags in permafrost thawing, and that the initial simulated net uptake of carbon may continue for some decades of warming. However, once the turning point is reached, if carbon release exceeds uptake, carbon is lost irreversibly from the system and cannot be compensated for by increasing vegetation carbon input. Our analysis highlights the importance of including dynamic vegetation and long-term responses into analyses of permafrost zone carbon budgets. (letter)

  1. Gasification biochar as soil amendment for carbon sequestration and soil quality

    DEFF Research Database (Denmark)

    Hansen, Veronika

    2014-01-01

    Thermal gasification of biomass is an efficient and flexible way to generate energy. Besides the energy, avaluable by-product, biochar, is produced. Biochar contains a considerable amount of recalcitrant carbon thathas potential for soil carbon sequestration and soil quality improvement if recycled...... back to agriculture soils. To determine the effect of gasification biochar on soil processes and crop yield, a short-term incubation study was conducted and a field trial has been established....

  2. Simulation of soil organic carbon in different soil size fractions using 13Carbon measurement data

    Science.gov (United States)

    Gottschalk, P.; Bellarby, J.; Chenu, C.; Foereid, B.; Wattenbach, M.; Zingore, S.; Smith, J.

    2009-04-01

    We simulate the soil organic carbon (SOC) dynamics at a chronoseqeunce site in France, using the Rothamsted Carbon model. The site exhibits a transition from C3 plants, dominated by pine forest, to a conventional C4 maize rotation. The different 13C signatures of the forest plants and maize are used to distinguish between the woodland derived carbon (C) and the maize derived C. The model is evaluated against total SOC and C derived from forest and maize, respectively. The SOC dynamics of the five SOC pools of the model, decomposable plant material (DPM), resistant plant material (RPM), biomass, humus and inert C, are also compared to the SOC dynamics measured in different soil size fractions. These fractions are > 50 μm (particulate organic matter), 2-50 μm (silt associated SOC) and 50 μm and the sum of the other pools corresponds well to the SOC measured in the soil size fraction minor effects on the simulations results. Accounting for erosion and implementing a simple tillage routine did not improve the simulation fit to the data. We therefore hypothesize that a generic process that is not yet explicitly accounted for in the ROTHC model could explain the loss in soil C after land use change. Such a process could be the loss of the physical protection of soil organic matter as would be observed following cultivation of a previously uncultivated soil. Under native conditions a fraction of organic matter is protected in stable soil aggregates. These aggregates are physically disrupted by continuous and repeated cultivation of the soil. The underestimation of SOC loss by the model can be mainly attributed to the slow turnover of the humus pool. This pool was shown to represent mainly the SOC associated with the silt and clay soil fraction. Here, the clay associated SOC shows as similar turnover time as the humus pool in the model. We split the humus pool into a clay and a silt associated pool. The clay pool now corresponds to the clay associated SOC with the

  3. CRADA Carbon Sequestration in Soils and Commercial Products

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, G.K.

    2002-01-31

    ORNL, through The Consortium for Research on Enhancing Carbon Sequestration in Terrestrial Ecosystems (CSiTE), collaborated with The Village Botanica, Inc. (VB) on a project investigating carbon sequestration in soils and commercial products from a new sustainable crop developed from perennial Hibiscus spp. Over 500 pre-treated samples were analyzed for soil carbon content. ORNL helped design a sampling scheme for soils during the planting phase of the project. Samples were collected and prepared by VB and analyzed for carbon content by ORNL. The project did not progress to a Phase II proposal because VB declined to prepare the required proposal.

  4. Distribution, stock, and influencing factors of soil organic carbon in ...

    Indian Academy of Sciences (India)

    40

    Distribution, stock, and influencing factors of soil organic carbon. 1 in an alpine meadow in the hinterland of the Qinghai-Tibetan. 2. Plateau. 3. XUCHAO ZHU1 and MING'AN SHAO2,3,*. 4. 1State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science,. 5. Chinese Academy of Sciences, 210008, Nanjing, ...

  5. Soil carbon pools and fluxes in urban ecosystems

    Science.gov (United States)

    R. Pouyat; P. Groffman; I Yesilonis; L. Hernandez

    2002-01-01

    The transformation of landscapes from non-urban to urban land use has the potential to greatly modify soil carbon (C) pools and fluxes. For urban ecosystems, very little data exists to assess whether urbanization leads to an increase or decrease in soil C pools. We analyzed three data sets to assess the potential for urbanization to affect soil organic C. These...

  6. Temporal variations in organic carbon, soil reactivity and aggregate ...

    African Journals Online (AJOL)

    We studied the effect of incorporating agricultural wastes on soil aggregate stability (AS), organic carbon (OC), and soil reactivity (pH) of similarly textured soils under different managements (vegetable, (VG) and Orchard (OR) farming), in South-eastern Nigeria. The agricultural wastes were cow dung (CD,) cassava peels ...

  7. Microbial Contribution to Organic Carbon Sequestration in Mineral Soil

    Science.gov (United States)

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

  8. Development of a Soil Organic Carbon Baseline for Otjozondjupa, Namibia

    OpenAIRE

    Nijbroek, R.; Kempen, B.; Mutua, J.; Soderstrom, M.; Piikki, K.; Hengari, S.; Andreas, A.

    2017-01-01

    Land Degradation Neutrality (LDN) has been piloted in 14 countries and will be scaled up to over 120 countries. As a LDN pilot country, Namibia developed sub-national LDN baselines in Otjozondjupa Region. In addition to the three LDN indicators (soil organic carbon, land productivity and land cover change), Namibia also regards bush encroachment as an important form of land degradation. We collected 219 soil profiles and used Random Forest modelling to develop the soil organic carbon stock ba...

  9. Effects of soil development time and litter quality on soil carbon sequestration: Assessing soil carbon saturation with a field transplant experiment along a post-mining chronosequence

    Czech Academy of Sciences Publication Activity Database

    Frouz, Jan

    2017-01-01

    Roč. 28, č. 2 (2017), s. 664-672 ISSN 1085-3278 Institutional support: RVO:60077344 Keywords : soil organic matter fractions * carbon sequestration * carbon saturation * mining * reclamation Subject RIV: DF - Soil Science OBOR OECD: Soil science Impact factor: 9.787, year: 2016

  10. Biofuel intercropping effects on soil carbon and microbial activity.

    Science.gov (United States)

    Strickland, Michael S; Leggett, Zakiya H; Sucre, Eric B; Bradford, Mark A

    2015-01-01

    Biofuels will help meet rising demands for energy and, ideally, limit climate change associated with carbon losses from the biosphere to atmosphere. Biofuel management must therefore maximize energy production and maintain ecosystem carbon stocks. Increasingly, there is interest in intercropping biofuels with other crops, partly because biofuel production on arable land might reduce availability and increase the price of food. One intercropping approach involves growing biofuel grasses in forest plantations. Grasses differ from trees in both their organic inputs to soils and microbial associations. These differences are associated with losses of soil carbon when grasses become abundant in forests. We investigated how intercropping switchgrass (Panicum virgalum), a major candidate for cellulosic biomass production, in loblolly pine (Pinus taeda) plantations affects soil carbon, nitrogen, and microbial dynamics. Our design involved four treatments: two pine management regimes where harvest residues (i.e., biomass) were left in place or removed, and two switchgrass regimes where the grass was grown with pine under the same two biomass scenarios (left or removed). Soil variables were measured in four 1-ha replicate plots in the first and second year following switchgrass planting. Under switchgrass intercropping, pools of mineralizable and particulate organic matter carbon were 42% and 33% lower, respectively. These declines translated into a 21% decrease in total soil carbon in the upper 15 cm of the soil profile, during early stand development. The switchgrass effect, however, was isolated to the interbed region where switchgrass is planted. In these regions, switchgrass-induced reductions in soil carbon pools with 29%, 43%, and 24% declines in mineralizable, particulate, and total soil carbon, respectively. Our results support the idea that grass inputs to forests can prime the activity of soil organic carbon degrading microbes, leading to net reductions in stocks

  11. Soil organic carbon response to shrub encroachment regulated by soil aggregates

    Science.gov (United States)

    Zhu, Y.; Li, H.; Shen, H.; Feng, Y.; Fang, J.

    2017-12-01

    Shrub encroachment leads to change in soil organic carbon content, but there still exists a lot of uncertainty in its mechanism as it relates to deep soil research. Soil organic carbon is usually associated with stable aggregate quantity. In this study, we conducted a field investigation for typical steppe and desert steppe in Inner Mongolia with the view to examining the impact of shrub encroachment on soil organic carbon with soil aggregate at a depth of 0-500 cm. The results show that in the desert steppe, the particle size of soil aggregate content level in different depth are presented the trend of shrub patches is lower than the herb matrix, organic carbon content of soil aggregate under 50 cm deeper presents the trend of shrub patches is higher than herb matrix, eventually leading to shrub patches whole soil organic carbon in the 0 to 50 cm depth lower than the herb matrix, and in deeper soil below 50 cm higher than the herb matrix. In the typical steppe, there is no significant difference between soil aggregate structure of shrub patches and herb matrix, but organic carbon content of soil aggregate, especially large aggregate organic carbon content in the shrub patches is significantly higher than the herb matrix, so that the whole soil organic carbon content in the shrub patches is significantly higher than herb matrix. The rate of soil organic carbon content change (0-100 cm) by shrub encroachment showed significant negative correlation with the mean weight diameter of soil aggregate of herb matrix. We also found that the variations of soil organic carbon in desert steppe is not dominant by aggregates of some size, but the change of the typical steppe soil organic carbon mainly contributed by > 0.25 mm and 0.053-0.25 mm aggregates. The results suggested that the effects of shrub encroachment on soil organic carbon is regulated by soil aggregate, but it is varied for different type of grassland, which should provide some insights into our understanding on

  12. Weathering controls on mechanisms of carbon storage in grassland soils

    Science.gov (United States)

    Masiello, C.A.; Chadwick, O.A.; Southon, J.; Torn, M.S.; Harden, J.W.

    2004-01-01

    On a sequence of soils developed under similar vegetation, temperature, and precipitation conditions, but with variations in mineralogical properties, we use organic carbon and 14C inventories to examine mineral protection of soil organic carbon. In these soils, 14C data indicate that the creation of slow-cycling carbon can be modeled as occurring through reaction of organic ligands with Al3+ and Fe3+ cations in the upper horizons, followed by sorption to amorphous inorganic Al compounds at depth. Only one of these processes, the chelation Al3+ and Fe3+ by organic ligands, is linked to large carbon stocks. Organic ligands stabilized by this process traverse the soil column as dissolved organic carbon (both from surface horizons and root exudates). At our moist grassland site, this chelation and transport process is very strongly correlated with the storage and long-term stabilization of soil organic carbon. Our 14C results show that the mechanisms of organic carbon transport and storage at this site follow a classic model previously believed to only be significant in a single soil order (Spodosols), and closely related to the presence of forests. The presence of this process in the grassland Alfisol, Inceptisol, and Mollisol soils of this chronosequence suggests that this process is a more significant control on organic carbon storage than previously thought. Copyright 2004 by the American Geophysical Union.

  13. A simple approach to estimate soil organic carbon and soil co/sub 2/ emission

    International Nuclear Information System (INIS)

    Abbas, F.

    2013-01-01

    SOC (Soil Organic Carbon) and soil CO/sub 2/ (Carbon Dioxide) emission are among the indicator of carbon sequestration and hence global climate change. Researchers in developed countries benefit from advance technologies to estimate C (Carbon) sequestration. However, access to the latest technologies has always been challenging in developing countries to conduct such estimates. This paper presents a simple and comprehensive approach for estimating SOC and soil CO/sub 2/ emission from arable- and forest soils. The approach includes various protocols that can be followed in laboratories of the research organizations or academic institutions equipped with basic research instruments and technology. The protocols involve soil sampling, sample analysis for selected properties, and the use of a worldwide tested Rothamsted carbon turnover model. With this approach, it is possible to quantify SOC and soil CO/sub 2/ emission over short- and long-term basis for global climate change assessment studies. (author)

  14. The Effect of Gasification Biochar on Soil Carbon Sequestration, Soil Quality and Crop Growth

    DEFF Research Database (Denmark)

    Hansen, Veronika

    have been raised about the potential negative impacts of incorporating bioenergy residuals (biochar) in soil and increasing the removal of crop residues such as straw, possibly reducing important soil functions and services for maintaining soil quality. Therefore, a combination of incubation studies...... and pot and field experiments was used to study the effect of straw and wood biochar on carbon sequestration, soil quality and crop growth. Overall, the biochar amendment improved soil chemical and physical properties and plant growth and showed a potential for soil carbon sequestration without having any...... negative impact on soil biota. However, the effects of biochar on soil quality and plant growth differed according to the biochar properties and the soil type used. Furthermore, the positive impact on some soil structural properties observed after straw incorporation was not achieved with biochar amendment...

  15. A global predictive model of carbon in mangrove soils

    International Nuclear Information System (INIS)

    Jardine, Sunny L; Siikamäki, Juha V

    2014-01-01

    Mangroves are among the most threatened and rapidly vanishing natural environments worldwide. They provide a wide range of ecosystem services and have recently become known for their exceptional capacity to store carbon. Research shows that mangrove conservation may be a low-cost means of reducing CO 2 emissions. Accordingly, there is growing interest in developing market mechanisms to credit mangrove conservation projects for associated CO 2 emissions reductions. These efforts depend on robust and readily applicable, but currently unavailable, localized estimates of soil carbon. Here, we use over 900 soil carbon measurements, collected in 28 countries by 61 independent studies, to develop a global predictive model for mangrove soil carbon. Using climatological and locational data as predictors, we explore several predictive modeling alternatives, including machine-learning methods. With our predictive model, we construct a global dataset of estimated soil carbon concentrations and stocks on a high-resolution grid (5 arc min). We estimate that the global mangrove soil carbon stock is 5.00 ± 0.94 Pg C (assuming a 1 meter soil depth) and find this stock is highly variable over space. The amount of carbon per hectare in the world’s most carbon-rich mangroves (approximately 703 ± 38 Mg C ha −1 ) is roughly a 2.6 ± 0.14 times the amount of carbon per hectare in the world’s most carbon-poor mangroves (approximately 272 ± 49 Mg C ha −1 ). Considerable within country variation in mangrove soil carbon also exists. In Indonesia, the country with the largest mangrove soil carbon stock, we estimate that the most carbon-rich mangroves contain 1.5 ± 0.12 times as much carbon per hectare as the most carbon-poor mangroves. Our results can aid in evaluating benefits from mangrove conservation and designing mangrove conservation policy. Additionally, the results can be used to project changes in mangrove soil carbon stocks based on changing climatological

  16. A global predictive model of carbon in mangrove soils

    Science.gov (United States)

    Jardine, Sunny L.; Siikamäki, Juha V.

    2014-10-01

    Mangroves are among the most threatened and rapidly vanishing natural environments worldwide. They provide a wide range of ecosystem services and have recently become known for their exceptional capacity to store carbon. Research shows that mangrove conservation may be a low-cost means of reducing CO2 emissions. Accordingly, there is growing interest in developing market mechanisms to credit mangrove conservation projects for associated CO2 emissions reductions. These efforts depend on robust and readily applicable, but currently unavailable, localized estimates of soil carbon. Here, we use over 900 soil carbon measurements, collected in 28 countries by 61 independent studies, to develop a global predictive model for mangrove soil carbon. Using climatological and locational data as predictors, we explore several predictive modeling alternatives, including machine-learning methods. With our predictive model, we construct a global dataset of estimated soil carbon concentrations and stocks on a high-resolution grid (5 arc min). We estimate that the global mangrove soil carbon stock is 5.00 ± 0.94 Pg C (assuming a 1 meter soil depth) and find this stock is highly variable over space. The amount of carbon per hectare in the world’s most carbon-rich mangroves (approximately 703 ± 38 Mg C ha-1) is roughly a 2.6 ± 0.14 times the amount of carbon per hectare in the world’s most carbon-poor mangroves (approximately 272 ± 49 Mg C ha-1). Considerable within country variation in mangrove soil carbon also exists. In Indonesia, the country with the largest mangrove soil carbon stock, we estimate that the most carbon-rich mangroves contain 1.5 ± 0.12 times as much carbon per hectare as the most carbon-poor mangroves. Our results can aid in evaluating benefits from mangrove conservation and designing mangrove conservation policy. Additionally, the results can be used to project changes in mangrove soil carbon stocks based on changing climatological predictors, e.g. to

  17. Modelling the soil carbon cycle of pine ecosystems

    International Nuclear Information System (INIS)

    Nakane, K.

    1994-01-01

    Soil carbon cycling rates and carbon budgets were calculated for stands of four pine species. Pinus sylvestris (at Jaedraaas, Sweden), P. densiflora (Hiroshima, Japan), P. elliottii (Florida, USA) and P. radiata (Canberra, Australia), using a simulation model driven by daily observations of mean air temperature and precipitation. Inputs to soil carbon through litterfall differ considerably among the four pine forests, but the accumulation of the A 0 layer and humus in mineral soil is less variable. Decomposition of the A 0 layer and humus is fastest for P. densiflora and slowest for P. sylvestris stands with P. radiata and P. elliottii intermediate. The decomposition rate is lower for the P. elliottii stand than for P. densiflora in spite of its higher temperatures and slightly higher precipitation. Seasonal changes in simulated soil carbon are observed only for the A 0 layer at the P. densiflora site. Simulated soil respiration rates vary seasonally in three stands (P. sylvestris, P. densiflora and P. radiata). In simulations for pine trees planted on bare soil, all soil organic matter fractions except the humus in mineral soil recover to half their asymptotic values within 30 to 40 years of planting for P. sylvestris and P. densiflora, compared with 10 to 20 years for P. radiata and P. elliottii. The simulated recovery of soil carbon following clear-cutting is fastest for the P. elliottii stand and slowest for P. sylvestris. Management of P. elliottii and P. radiata stands on 40-years rotations is sustainable because carbon removed through harvest is restored in the interval between successive clear-cuts. However p. densiflora and P. sylvestris stands may be unable to maintain soil carbon under such a short rotation. High growth rates of P. elliottii and p. radiata stands in spite of relatively poor soil conditions and slow carbon cycling may be related to the physiological responses of species to environmental conditions. (Abstract Truncated)

  18. Mineral protection of soil carbon counteracted by root exudates

    Science.gov (United States)

    Keiluweit, Marco; Bougoure, Jeremy J.; Nico, Peter S.; Pett-Ridge, Jennifer; Weber, Peter K.; Kleber, Markus

    2015-06-01

    Multiple lines of existing evidence suggest that climate change enhances root exudation of organic compounds into soils. Recent experimental studies show that increased exudate inputs may cause a net loss of soil carbon. This stimulation of microbial carbon mineralization (`priming’) is commonly rationalized by the assumption that exudates provide a readily bioavailable supply of energy for the decomposition of native soil carbon (co-metabolism). Here we show that an alternate mechanism can cause carbon loss of equal or greater magnitude. We find that a common root exudate, oxalic acid, promotes carbon loss by liberating organic compounds from protective associations with minerals. By enhancing microbial access to previously mineral-protected compounds, this indirect mechanism accelerated carbon loss more than simply increasing the supply of energetically more favourable substrates. Our results provide insights into the coupled biotic-abiotic mechanisms underlying the `priming’ phenomenon and challenge the assumption that mineral-associated carbon is protected from microbial cycling over millennial timescales.

  19. Net carbon allocation in soybean seedlings as influenced by soil water stress at two soil temperatures

    International Nuclear Information System (INIS)

    McCoy, E.L.; Boersma, L.; Ekasingh, M.

    1990-01-01

    The influence of water stress at two soil temperatures on allocation of net photoassimilated carbon in soybean (Glycine max [L.] Merr.) was investigated using compartmental analysis. The experimental phase employed classical 14 C labeling methodology with plants equilibrated at soil water potentials of -0.04, -0.25 and -0.50 MPa; and soil temperatures of 25 and 10C. Carbon immobilization in the shoot apex generally followed leaf elongation rates with decreases in both parameters at increasing water stress at both soil temperatures. However, where moderate water stress resulted in dramatic declines in leaf elongation rates, carbon immobilization rates were sharply decreased only at severe water stress levels. Carbon immobilization was decreased in the roots and nodules of the nonwater stressed treatment by the lower soil temperature. This relation was reversed with severe water stress, and carbon immobilization in the roots and nodules was increased at the lower soil temperature. Apparently, the increased demand for growth and/or carbon storage in these tissues with increased water stress overcame the low soil temperature limitations. Both carbon pool sizes and partitioning of carbon to the sink tissues increased with moderate water stress at 25C soil temperature. Increased pool sizes were consistent with whole plant osmotic adjustment at moderate water stress. Increased partitioning to the sinks was consistent with carbon translocation processes being less severely influenced by water stress than is photosynthesis

  20. 137Cesium and soil carbon in a small agricultural watershed

    International Nuclear Information System (INIS)

    Ritchie, J.C.; McCarty, G.W.

    2003-01-01

    Scientific, political, and social interests have developed recently in the concept of using agricultural soils to sequester carbon. Studies supporting this concept indicate that soil erosion and subsequent redeposition of eroded soils in the same field may establish an ecosystem disequilibrium that promotes the buildup of carbon on agricultural landscapes. The problem is to determine the patterns of soil erosion and redeposition on the landscape and to relate these to soil carbon patterns. Radioactive 137 cesium ( 137 Cs) can be used to estimate soil erosion patterns and, more importantly, redeposition patterns at the field level. The purpose of this study was to determine the relationship between 137 Cs, soil erosion, and soil carbon patterns on a small agricultural watershed. Profiles of soils from an upland area and soils in an adjacent riparian system were collected in 5 cm increments and the concentrations of 137 Cs and carbon were determined. 137 Cs and carbon were uniformly mixed in the upper 15-20 cm of upland soils. 137 Cs (Bq g -1 ) and carbon (%) in the upland soils were significantly correlated (r 2 =0.66). Carbon content of the 0-20 cm layer was higher (1.4±0.3%) in areas of soil deposition than carbon content (1.1±0.3%) in areas of soil erosion as determined by the 137 Cs technique. These data suggest that measurements of 137 Cs in the soils can be useful for understanding carbon distribution patterns in surface soil. Carbon content of the upland soils ranged from 0.5 to 1.9% with an average of 1.2±0.4% in the 0-20 cm layer while carbon below this upper tilled layer (20-30 cm) ranged from 0.2 to 1.5% with an average of 0.5±0.3%. Total carbon was 2.66 and 3.20 kg m -2 in the upper 20 cm and upper 30 cm of the upland soils, respectively. Carbon content of the 0-20 cm layer in the riparian system ranged from 1.1 to 67.0% with an average 11.7±17.1%. Carbon content below 20 cm ranged from 1.8 to 79.3% with an average of 18.3±17.5%. Soil carbon in the

  1. Influence of land use changes on soil carbon stock and soil carbon erosion in a Mediterranean catchment

    International Nuclear Information System (INIS)

    Boix-Fayos, C.; Martinez-Mena, M.; Vente, J. de; Albaladejo, J.

    2009-01-01

    The effect of changing land uses on the organic soil carbon (C) stock and the soil C transported by water erosion and buried in depositions wedges behring check-dams was estimated in a Mediterranean catchment in SE Spin. the 57% decrease in agricultural areas and 1.5-fold increase of the total forest cover between 1956 and 1997 induced an accumulation rate of total organic carbon (TOC) in the soil of 10.73 g m - 2 yr - 1. The mineral-associated organic carbon (MOC) represented the 70% of the soil carbon pool, the particulate organic carbon (POC) represented a 30% of the soil carbon pool. The average sediments/soil enrichment ratio at the sub catchment scale (8-125 ha) was 0.59±0.43 g kg - 1. Eroded soil C accounted for between 2% to 78% of the soil c stock in the first 5 cm of the soil in the subcatchments. the C erosion rate varied between 0.008 and 0.2 t ha - 1 yr - 1. (Author) 20 refs.

  2. Impact of priming on global soil carbon stocks.

    Science.gov (United States)

    Guenet, Bertrand; Camino-Serrano, Marta; Ciais, Philippe; Tifafi, Marwa; Maignan, Fabienne; Soong, Jennifer L; Janssens, Ivan A

    2018-01-24

    Fresh carbon input (above and belowground) contributes to soil carbon sequestration, but also accelerates decomposition of soil organic matter through biological priming mechanisms. Currently, poor understanding precludes the incorporation of these priming mechanisms into the global carbon models used for future projections. Here, we show that priming can be incorporated based on a simple equation calibrated from incubation and verified against independent litter manipulation experiments in the global land surface model, ORCHIDEE. When incorporated into ORCHIDEE, priming improved the model's representation of global soil carbon stocks and decreased soil carbon sequestration by 51% (12 ± 3 Pg C) during the period 1901-2010. Future projections with the same model across the range of CO 2 and climate changes defined by the IPCC-RCP scenarios reveal that priming buffers the projected changes in soil carbon stocks - both the increases due to enhanced productivity and new input to the soil, and the decreases due to warming-induced accelerated decomposition. Including priming in Earth system models leads to different projections of soil carbon changes, which are challenging to verify at large spatial scales. © 2018 John Wiley & Sons Ltd.

  3. ORCHIDEE-SOM: modeling soil organic carbon (SOC) and dissolved organic carbon (DOC) dynamics along vertical soil profiles in Europe

    Science.gov (United States)

    Camino-Serrano, Marta; Guenet, Bertrand; Luyssaert, Sebastiaan; Ciais, Philippe; Bastrikov, Vladislav; De Vos, Bruno; Gielen, Bert; Gleixner, Gerd; Jornet-Puig, Albert; Kaiser, Klaus; Kothawala, Dolly; Lauerwald, Ronny; Peñuelas, Josep; Schrumpf, Marion; Vicca, Sara; Vuichard, Nicolas; Walmsley, David; Janssens, Ivan A.

    2018-03-01

    Current land surface models (LSMs) typically represent soils in a very simplistic way, assuming soil organic carbon (SOC) as a bulk, and thus impeding a correct representation of deep soil carbon dynamics. Moreover, LSMs generally neglect the production and export of dissolved organic carbon (DOC) from soils to rivers, leading to overestimations of the potential carbon sequestration on land. This common oversimplified processing of SOC in LSMs is partly responsible for the large uncertainty in the predictions of the soil carbon response to climate change. In this study, we present a new soil carbon module called ORCHIDEE-SOM, embedded within the land surface model ORCHIDEE, which is able to reproduce the DOC and SOC dynamics in a vertically discretized soil to 2 m. The model includes processes of biological production and consumption of SOC and DOC, DOC adsorption on and desorption from soil minerals, diffusion of SOC and DOC, and DOC transport with water through and out of the soils to rivers. We evaluated ORCHIDEE-SOM against observations of DOC concentrations and SOC stocks from four European sites with different vegetation covers: a coniferous forest, a deciduous forest, a grassland, and a cropland. The model was able to reproduce the SOC stocks along their vertical profiles at the four sites and the DOC concentrations within the range of measurements, with the exception of the DOC concentrations in the upper soil horizon at the coniferous forest. However, the model was not able to fully capture the temporal dynamics of DOC concentrations. Further model improvements should focus on a plant- and depth-dependent parameterization of the new input model parameters, such as the turnover times of DOC and the microbial carbon use efficiency. We suggest that this new soil module, when parameterized for global simulations, will improve the representation of the global carbon cycle in LSMs, thus helping to constrain the predictions of the future SOC response to global

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

    International Nuclear Information System (INIS)

    Post, W.M. III.

    1988-01-01

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

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

    Science.gov (United States)

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

    2010-01-01

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

  6. Accounting for carbon stocks in soils and measuring GHGs emission fluxes from soils

    NARCIS (Netherlands)

    Bispo, Antonio; Andersen, Lizzi; Angers, Denis A.; Bernoux, Martial; Brossard, Michel; Cécillon, Lauric; Comans, Rob N.J.; Harmsen, Joop; Jonassen, Knut; Lamé, Frank; Lhuillery, Caroline; Maly, Stanislav; Martin, Edith; Mcelnea, Angus E.; Sakai, Hiro; Watabe, Yoichi; Eglin, Thomas K.

    2017-01-01

    Soil is a key compartment for climate regulation as a source of greenhouse gases (GHGs) emissions and as a sink of carbon. Thus, soil carbon sequestration strategies should be considered alongside reduction strategies for other greenhouse gas emissions. Taking this into account, several

  7. Assessing soil constituents and labile soil organic carbon by midinfrared photoacoustic spectroscopy

    DEFF Research Database (Denmark)

    Peltre, Clément; Bruun, Sander; Du, Changwen

    2014-01-01

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

  8. Deep Soil Carbon: The Insight into Global Carbon Estimation and Deforestation Impacts

    Science.gov (United States)

    Sangmanee, Podjanee; Dell, Bernard; Harper, Richard; Henry, David

    2015-04-01

    World carbon stocks have been dramatically changed by deforestation. The current estimation of carbon loss is based on allometric techniques assisted with satellite imagery and the assumption that, 20% of the total biomass carbon stock is below ground. However, the monitoring of soil carbon is limited to 0.3 m despite many soils being much deeper than this. For example, direct measurement of soil carbon demonstrated the occurrence of two to five times more carbon stored in deep soils of south Western Australia (SWA) compared to what would normally be reported, although the land had been deforested for 80 years. This raises important questions about the dynamics of this deeper carbon and whether it will contribute to global climate change. This paper reports the form and variation of carbon in soil at three adjacent areas at three different depths (0-1, 11-12 and 18-19 m). Techniques were developed to quantitatively and qualitatively determine small concentrations of carbon in deep soils. There were marked differences in carbon compounds with depth. Near the surface these were macromolecular organic compounds derived from lignin, polysaccharides, proteins, terpenes, whereas at depth they were low molecular weight compounds, 13-docosenamide, 13-docosenoate, xanthone, benzophenone. The deeper compounds are likely derived from the roots of the previous forest whereas the surface soils are affected by current land use. The in situ decomposition of deep roots was revealed by the pyridine compound. The variation of compounds and location of carbon in clay could imply the state of decomposition. The result demonstrated that carbon is contained in deep soils and should be considered in global carbon accounting, particularly given ongoing deforestation on deep soils.

  9. GlobalSoilMap for Soil Organic Carbon Mapping and as a Basis for Global Modeling

    NARCIS (Netherlands)

    Arrouays, D.; Minasny, B.; McBratney, A.; Grundy, Mike; McKenzie, Neil; Thompson, James; Gimona, Alessandro; Hong, Suk Young; Smith, Scott; Hartemink, A.E.; Chen, Songchao; Martin, Manuel P.; Mulder, V.L.; Richer-de-Forges, A.C.; Odeh, Inakwu; Padarian, José; Lelyk, Glenn; Poggio, Laura; Savin, Igor; Stolbovoy, Vladimir; Leenaars, J.G.B.; Heuvelink, G.B.M.; Montanarella, Luca; Panagos, P.; Hempel, Jon

    2017-01-01

    The demand for information on functional soil properties is high and has increased over time. This is especially true for soil organic carbon (SOC) in the framework of food security and climate change. The GlobalSoilMap consortium was established in response to such a soaring demand for

  10. Soil-water repellency characteristic curves for soil profiles with organic carbon gradients

    DEFF Research Database (Denmark)

    Wijewardana, Nadeeka Senani; Müller, Karin; Møldrup, Per

    2016-01-01

    Highlights •Water repellency at different soil organic carbon (SOC) contents was measured. •Repellency was restricted to the top 20 cm of the soil profiles. •The sessile drop method is highly sensitive at high SOC contents. •We proposed six repellency parameters for repellent soils. •Functions...

  11. Grassland management impacts on soil carbon stocks: a new synthesis.

    Science.gov (United States)

    Conant, Richard T; Cerri, Carlos E P; Osborne, Brooke B; Paustian, Keith

    2017-03-01

    Grassland ecosystems cover a large portion of Earths' surface and contain substantial amounts of soil organic carbon. Previous work has established that these soil carbon stocks are sensitive to management and land use changes: grazing, species composition, and mineral nutrient availability can lead to losses or gains of soil carbon. Because of the large annual carbon fluxes into and out of grassland systems, there has been growing interest in how changes in management might shift the net balance of these flows, stemming losses from degrading grasslands or managing systems to increase soil carbon stocks (i.e., carbon sequestration). A synthesis published in 2001 assembled data from hundreds of studies to document soil carbon responses to changes in management. Here we present a new synthesis that has integrated data from the hundreds of studies published after our previous work. These new data largely confirm our earlier conclusions: improved grazing management, fertilization, sowing legumes and improved grass species, irrigation, and conversion from cultivation all tend to lead to increased soil C, at rates ranging from 0.105 to more than 1 Mg C·ha -1 ·yr -1 . The new data include assessment of three new management practices: fire, silvopastoralism, and reclamation, although these studies are limited in number. The main area in which the new data are contrary to our previous synthesis is in conversion from native vegetation to grassland, where we find that across the studies the average rate of soil carbon stock change is low and not significant. The data in this synthesis confirm that improving grassland management practices and conversion from cropland to grassland improve soil carbon stocks. © 2016 by the Ecological Society of America.

  12. Soil organic carbon fractionation for improving agricultural soil quality diagnosis in Southern Belgium (Wallonia).

    Science.gov (United States)

    Chartin, Caroline; Trigalet, Sylvain; Castaldi, Fabio; Krüger, Inken; Carnol, Monique; van Wesemael, Bas

    2017-04-01

    We propose a simple method for separating bulk Soil Organic Carbon (SOC) into meaningful fractions to better diagnose soil quality, related to soil ecosystem functions and C sequestration potential. Soils under croplands and grasslands, and under both conventional and conservation management practices, have been analyzed all over the Southern part of Belgium (Wallonia). By separating carbon associated with clay and fine silt particles (stable carbon with slow turnover rate, 20 µm), effects of long-term and medium/short-term managements can be detected more efficiently at different scales. Values of stable carbon fraction for soil under grasslands are analyzed and used to create a theoretical stable carbon saturation curve for assessing carbon sequestration potential of Walloon soils. This theoretical curve is compared to Hassink's (1997) equation. Thus a saturation deficit of cropland soils can be determined and the effect of management practices can be assessed. Besides, spectroscopic analyses are performed on the bulk soil samples to test the potential for accurately estimating total SOC and stable SOC fraction in soil routine analysis performed by Walloon Public Services for local farmers.

  13. The distribution in lunar soil of carbon released by pyrolysis

    Science.gov (United States)

    Desmarais, D. J.; Hayes, J. M.; Meinschein, W. G.

    1973-01-01

    The carbon contents of various lunar soil particle types and sieve fractions of Apollo 15 and 16 samples have been determined by the pyrolysis method. The mineral, glass, and high-grade breccia fragments in the soils examined contain relatively low amounts of carbon (approximately 8, 25, and 25 microg C/g sample respectively in 149-250 micron grains). Most low-grade breccias and all agglutinates examined have high carbon contents (approximately 52 and 80 microg C/g sample respectively), and agglutinate abundance is indicative of the carbon content and maturity of a soil. The distribution of carbon with respect to particle size in mature soils generally reveals a minimum in carbon content at about 100 micron particle diameter. At smaller particle diameters, carbon content is directly proportional to particle surface area and therefore increases with the ratio (surface area)/(particle mass). A model relating the cycle of comminution and aggregation of soil particles to the redistribution of surface implanted carbon is developed.

  14. Elevated carbon dioxide: impacts on soil and plant water relations

    National Research Council Canada - National Science Library

    Kirkham, M. B

    2011-01-01

    .... Focusing on this critical issue, Elevated Carbon Dioxide: Impacts on Soil and Plant Water Relations presents research conducted on field-grown sorghum, winter wheat, and rangeland plants under elevated CO2...

  15. Offsetting China's CO2 Emissions by Soil Carbon Sequestration

    International Nuclear Information System (INIS)

    Lal, R.

    2004-01-01

    Fossil fuel emissions of carbon (C) in China in 2000 was about 1 Pg/yr, which may surpass that of the U.S. (1.84 Pg C) by 2020. Terrestrial C pool of China comprises about 35 to 60 Pg in the forest and 120 to 186 Pg in soils. Soil degradation is a major issue affecting 145 Mha by different degradative processes, of which 126 Mha are prone to accelerated soil erosion. Similar to world soils, agricultural soils of China have also lost 30 to 50% or more of the antecedent soil organic carbon (SOC) pool. Some of the depleted SOC pool can be re-sequestered through restoration of degraded soils, and adoption of recommended management practices. The latter include conversion of upland crops to multiple cropping and rice paddies, adoption of integrated nutrient management (INM) strategies, incorporation of cover crops in the rotations cycle and adoption of conservation-effective systems including conservation tillage. A crude estimated potential of soil C sequestration in China is 119 to 226 Tg C/y of SOC and 7 to 138 Tg C/y for soil inorganic carbon (SIC) up to 50 years. The total potential of soil C sequestration is about 12 Pg, and this potential can offset about 25% of the annual fossil fuel emissions in China

  16. Integrating microbial diversity in soil carbon dynamic models parameters

    Science.gov (United States)

    Louis, Benjamin; Menasseri-Aubry, Safya; Leterme, Philippe; Maron, Pierre-Alain; Viaud, Valérie

    2015-04-01

    Faced with the numerous concerns about soil carbon dynamic, a large quantity of carbon dynamic models has been developed during the last century. These models are mainly in the form of deterministic compartment models with carbon fluxes between compartments represented by ordinary differential equations. Nowadays, lots of them consider the microbial biomass as a compartment of the soil organic matter (carbon quantity). But the amount of microbial carbon is rarely used in the differential equations of the models as a limiting factor. Additionally, microbial diversity and community composition are mostly missing, although last advances in soil microbial analytical methods during the two past decades have shown that these characteristics play also a significant role in soil carbon dynamic. As soil microorganisms are essential drivers of soil carbon dynamic, the question about explicitly integrating their role have become a key issue in soil carbon dynamic models development. Some interesting attempts can be found and are dominated by the incorporation of several compartments of different groups of microbial biomass in terms of functional traits and/or biogeochemical compositions to integrate microbial diversity. However, these models are basically heuristic models in the sense that they are used to test hypotheses through simulations. They have rarely been confronted to real data and thus cannot be used to predict realistic situations. The objective of this work was to empirically integrate microbial diversity in a simple model of carbon dynamic through statistical modelling of the model parameters. This work is based on available experimental results coming from a French National Research Agency program called DIMIMOS. Briefly, 13C-labelled wheat residue has been incorporated into soils with different pedological characteristics and land use history. Then, the soils have been incubated during 104 days and labelled and non-labelled CO2 fluxes have been measured at ten

  17. Spatial distribution of soil organic carbon stocks in France

    Directory of Open Access Journals (Sweden)

    M. P. Martin

    2011-05-01

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

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

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

  18. Pasture Management Strategies for Sequestering Soil Carbon - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Franzluebbers, Alan J.

    2006-03-15

    Pasturelands account for 51 of the 212 Mha of privately held grazing land in the USA. Tall fescue is the most important cool-season perennial forage for many beef cattle producers in the humid region of the USA. A fungal endophyte, Neotyphodium coenophialum, infects the majority of tall fescue stands with a mutualistic association. Ergot alkaloids produced by the endophyte have negative impacts on cattle performance. However, there are indications that endophyte infection of tall fescue is a necessary component of productive and persistent pasture ecology. The objectives of this research were to characterize and quantify changes in soil organic carbon and associated soil properties under tall fescue pastures with and without endophyte infection of grass. Pastures with high endophyte infection had greater concentration of soil organic carbon, but lower concentration of biologically active soil carbon than pastures with low endophyte infection. A controlled experiment suggested that endophyte-infected leaf tissue may directly inhibit the activity of soil microorganisms. Carbon forms of soil organic matter were negatively affected and nitrogen forms were positively affected by endophyte addition to soil. The chemical compounds in endophyte-infected tall fescue (ergot alkaloids) that are responsible for animal health disorders were found in soil, suggesting that these chemicals might be persistent in the environment. Future research is needed to determine whether ergot alkaloids or some other chemicals are responsible for increases in soil organic matter. Scientists will be able to use this information to better understand the ecological impacts of animals grazing tall fescue, and possibly to identify and cultivate other similar associations for improving soil organic matter storage. Another experiment suggested that both dry matter production and soil microbial activity could be affected by the endophyte. Sampling of the cumulative effects of 20 years of tall fescue

  19. The Influence of Urban Soil Rehabilitation on Soil Carbon Dynamics, Greenhouse Gas Emission, and Stormwater Mitigation

    OpenAIRE

    Chen, Yujuan

    2013-01-01

    Global urbanization has resulted in rapidly increased urban land. Soils are the foundation that supports plant growth and human activities in urban areas. Furthermore, urban soils have potential to provide a carbon sink to mitigate greenhouse gas emission and climate change. However, typical urban land development practices including vegetation clearing, topsoil removal, stockpiling, compaction, grading and building result in degraded soils. In this work, we evaluated an urban soil rehabilita...

  20. Managing U.S. cropland to sequester carbon in soil

    Energy Technology Data Exchange (ETDEWEB)

    Lal, R. [Ohio State Univ., Columbus, OH (United States). School of Natural Resources; Follett, R.F. [USDA-ARS, Fort Collins, CO (United States); Kimble, J. [USDA-NRCS, Lincoln, NE (United States). National Soil Survey Center; Cole, C.V. [Colorado State Univ., Estes Park, CO (United States)

    1999-01-01

    The effects of human activities on atmospheric concentrations of carbon dioxide (CO{sub 2}) and other greenhouse gases (GHGs) are under intensive study in the United States and worldwide. Since conversion to cropland during the 17th and 18th centuries, the vegetation and soils of the US forests, grasslands, and wetlands have undergone extensive change. Clearing, tilling, and draining of these soils for long-term cropland use released large amounts of CO{sub 2}, a GHG, to the atmosphere from the soils` fertile soil organic matter (SOM). The SOM in topsoil often was depleted by up to half of its soil organic carbon (SOC). Now, improved farming technologies, increased farmland productivity, and government programs to return highly erodible lands to permanent vegetation are producing unanticipated benefits by letting soils become major sinks for atmospheric CO{sub 2} that is stored in them as increasing levels of SOC.

  1. Carbon Stock Stratification of Peat Soils in South Kalimantan, Indonesia

    Directory of Open Access Journals (Sweden)

    Siti Nurzakiah

    2015-05-01

    Full Text Available Carbon stock in peat soils is very high, it is necessary to prudent in its management because peat soils is emitting greenhouse gases such as CO2 during land clearing due to oxidation of peat layer.  This research was conducted to study soil carbon stock stratification in relation to soil physical and chemical properties. The carbon stock stratification was based on maturity degrees of peat.  The study was conducted in Pulau Damar Village, Hulu Sungai Utara District, South Kalimantan Province on land use rubber.  The location of the study area was determined by using the purposive sampling method.  All data obtained were analyzed by Excel spreadsheets and drawn on a CorelDraw 12. The results showed that the amount of carbon stock was influenced by the maturity degrees of peats, peat sapric degres has higher carbon stock than of hemik and fibric with a ratio of  2.0: 1.5: 1.  The relationship between soil carbon stock with soil physic (Bulk Density, BD and chemical properties (pH, Eh, Fe, and total-N were not significantly.

  2. Carbon Sequestration in Forests and Agricultural Soils (Invited)

    Science.gov (United States)

    Schlesinger, W. H.

    2010-12-01

    Numerous proposals are before policy makers for enhanced carbon sequestration in terrestrial ecosystems—forests and agricultural soils—yielding carbon offsets in cap-and-trade systems aimed to control net U.S. emissions of greenhouse gases to the atmosphere. Each of these proposals should be examined carefully to evaluate its additionality, permanence and leakage characteristics . Carbon storage in forests is more rapid than in soils and often more efficient, given the higher C/N ratio in wood than in soil organic materials. The efficacy of maintaining carbon storage in old-growth forests, versus providing enhanced carbon uptake in younger, plantation forests, largely tips in favor of old-growth. Nevertheless, even planting fast-growing species would require an area the size of the state of Texas to sequester 10% of the current U.S. CO2 emissions. Schemes to enhance carbon storage in agricultural soils, derived from the adoption of no- or low-tlll technologies, fertilization, irrigation and biochar application, also need careful evaluation. The most efficient storage is likely to be found in areas of cold, wet soils, with impeded decomposition. In the best case scenarios, it will be unlikely to sequester more than 5% of U.S. emissions as enhanced soil organic matter in cropland soils.

  3. Carbon footprint of milk from sheep farming systems in northern Spain including soil carbon sequestration in grasslands

    DEFF Research Database (Denmark)

    Batalla, Inma M.; Knudsen, Marie Trydeman; Mogensen, Lisbeth

    2015-01-01

    sequestration in the carbon footprint calculations. Especially in grasslands, soil carbon sequestration might be a potential sink to mitigate greenhouse gas emissions in the livestock sector. However, there is no commonly accepted methodology on how to include soil carbon sequestration in carbon footprint...... calculations. In this study, the carbon footprint of sheep milk was estimated from 12 farms in Northern Spain. Before taken into account contribution from soil carbon sequestration in the calculation, the carbon footprint values varied from 2.0 to 5.2 kg CO2 eq. per kg Fat and Protein Corrected Milk (FPCM...... and breeds when soil carbon sequestration was included in the calculations. Four different approaches to estimate and include soil carbon sequestration in the carbon footprint calculations were tested. This study highlights the importance of including soil carbon sequestration in the carbon footprint...

  4. Quantifying the Stock of Soil Organic Carbon using Multiple ...

    African Journals Online (AJOL)

    The stepwise multiple regression model was employed to identify ecological variables that explained significant variation of carbon in fallow soils. Using fallow genealogical cycles of 1st, 2nd, 3rd, 4th and 5th generations, soil and vegetation variables from 30 sampling plots were collected and subjected to linear regression ...

  5. Contribution of root to soil respiration and carbon balance in ...

    Indian Academy of Sciences (India)

    PRAKASH

    Global soil respiration is estimated to be 76.5 Pg C yr-1, which is 30–60 Pg C yr-1 greater than the net primary productivity. (NPP) (Raich and Potter 1995). Therefore, soil respiration is a major pathway for carbon to move from terrestrial ecosystems to the atmosphere and even small changes can strongly influence net ...

  6. 1 Soil Organic Carbon Dynamics under different plantation crops of ...

    African Journals Online (AJOL)

    Using the SOC as indicator, the soil organic matter content needs to be improved upon for sustainable productivity. ... microorganisms which are involved in litter degradation process. However, there. J S Ogeh* ... by the linear regression study. Keywords: Soil organic carbon, plantation crops, different ages, tropics, cashew,.

  7. Soil fauna: key to new carbon models

    NARCIS (Netherlands)

    Filser, Juliane; Faber, J.H.; Tiunov, Alexei V.; Brussaard, L.; Frouz, J.; Deyn, de G.B.; Uvarov, Alexei V.; Berg, Matty P.; Lavelle, Patrick; Loreau, M.; Wall, D.H.; Querner, Pascal; Eijsackers, Herman; Jimenez, Juan Jose

    2016-01-01

    Soil organic matter (SOM) is key to maintaining soil fertility, mitigating climate change, combatting land degradation, and conserving above- and below-ground biodiversity and associated soil processes and ecosystem services. In order to derive management options for maintaining these essential

  8. The temperature sensitivity of soil organic carbon decomposition is not related to labile and recalcitrant carbon.

    Science.gov (United States)

    Tang, Jie; Cheng, Hao; Fang, Changming

    2017-01-01

    The response of resistant soil organic matter to temperature change is crucial for predicting climate change impacts on C cycling in terrestrial ecosystems. However, the response of the decomposition of different soil organic carbon (SOC) fractions to temperature is still under debate. To investigate whether the labile and resistant SOC components have different temperature sensitivities, soil samples were collected from three forest and two grass land sites, along with a gradient of latitude from 18°40'to 43°17'N and elevation from 600 to 3510 m across China, and were incubated under changing temperature (from 12 to 32 oC) for at least 260 days. Soil respiration rates were positively related to the content of soil organic carbon and soil microbial carbon. The temperature sensitivity of soil respiration, presented as Q10 value, varies from 1.93 ± 0.15 to 2.60 ± 0.21. During the incubation, there were no significant differences between the Q10 values of soil samples from different layers of the same site, nor a clear pattern of Q10 values along with the gradient of latitude. The result of this study does not support current opinion that resistant soil carbon decomposition is more sensitive to temperature change than labile soil carbon.

  9. Accounting for Organic Carbon Change in Deep Soil Altered Carbon Sequestration Efficiency

    Science.gov (United States)

    Li, J.; Liang, F.; Xu, M.; Huang, S.

    2017-12-01

    Study on soil organic carbon (SOC) sequestration under fertilization practices in croplands lacks information of soil C change at depth lower than plow layer (i.e. 20 30-cm). By synthesizing long-term datasets of fertilization experiments in four typical Chinese croplands representing black soil at Gongzhuling(GZL), aquatic Chao soil at Zhengzhou(ZZ), red soil at Qiyang(QY) and purple soil at Chongqing(CQ) city, we calculated changes in SOC storage relative to initial condition (ΔSOC) in 0-20cm and 0-60cm, organic C inputs (OC) from the stubble, roots and manure amendment, and C sequestration efficiency (CSE: the ratio of ΔSOC over OC) in 0-20cm and 0-60cm. The fertilization treatments include cropping with no fertilization (CK), chemical nitrogen, phosphorus and potassium fertilizers (NPK) and combined chemical fertilizers and manure (NPKM). Results showed SOC storage generally decreased with soil depth (i.e. 0-20 > 20-40, 40-60 cm) and increased with fertilizations (i.e. initial 20cm) can act as important soil carbon sinks in intrinsically high fertility soils (i.e. black soil) but less likely at poor fertility soil (i.e. aquatic Chao soil). It thus informs the need to account for C change in deep soils for estimating soil C sequestration capacity particularly with indigenously fertile cropland soils.

  10. Stable isotopic constraints on global soil organic carbon turnover

    Science.gov (United States)

    Wang, Chao; Houlton, Benjamin Z.; Liu, Dongwei; Hou, Jianfeng; Cheng, Weixin; Bai, Edith

    2018-02-01

    Carbon dioxide release during soil organic carbon (SOC) turnover is a pivotal component of atmospheric CO2 concentrations and global climate change. However, reliably measuring SOC turnover rates on large spatial and temporal scales remains challenging. Here we use a natural carbon isotope approach, defined as beta (β), which was quantified from the δ13C of vegetation and soil reported in the literature (176 separate soil profiles), to examine large-scale controls of climate, soil physical properties and nutrients over patterns of SOC turnover across terrestrial biomes worldwide. We report a significant relationship between β and calculated soil C turnover rates (k), which were estimated by dividing soil heterotrophic respiration rates by SOC pools. ln( - β) exhibits a significant linear relationship with mean annual temperature, but a more complex polynomial relationship with mean annual precipitation, implying strong-feedbacks of SOC turnover to climate changes. Soil nitrogen (N) and clay content correlate strongly and positively with ln( - β), revealing the additional influence of nutrients and physical soil properties on SOC decomposition rates. Furthermore, a strong (R2 = 0.76; p global models of soil C turnover and thereby improving predictions of multiple global change influences over terrestrial C-climate feedback.

  11. Soil carbon model alternatives for ECHAM5/JSBACH climate model: Evaluation and impacts on global carbon cycle estimates

    DEFF Research Database (Denmark)

    Thum, T.; Raisanen, P.; Sevanto, S.

    2011-01-01

    The response of soil organic carbon to climate change might lead to significant feedbacks affecting global warming. This response can be studied by coupled climate-carbon cycle models but so far the description of soil organic carbon cycle in these models has been quite simple. In this work we used...... the coupled climate-carbon cycle model ECHAM5/JSBACH (European Center/Hamburg Model 5/Jena Scheme for Biosphere-Atmosphere Coupling in Hamburg) with two different soil carbon modules, namely (1) the original soil carbon model of JSBACH called CBALANCE and (2) a new soil carbon model Yasso07, to study...... the interaction between climate variability and soil organic carbon. Equivalent ECHAM5/JSBACH simulations were conducted using both soil carbon models, with freely varying atmospheric CO2 for the last 30 years (1977-2006). In this study, anthropogenic CO2 emissions and ocean carbon cycle were excluded. The new...

  12. Insights into soil carbon dynamics across climatic gradients from carbon-pool specific radiocarbon analyses

    Science.gov (United States)

    van der Voort, Tessa Sophia; Hagedorn, Frank; McIntyre, Cameron; Zell, Claudia; Eglinton, Timothy Ian

    2017-04-01

    Soil carbon constitutes the largest terrestrial reservoir of organic carbon, and therefore understanding the mechanisms and drivers of carbon stabilization is crucial, especially in the framework of climate change. The understanding of the dependence of soil organic turnover in specific carbon pools as related to e.g. climate, soil texture and mineralogy is limited. In this framework, radiocarbon constitutes a uniquely powerful tool that help to unravel carbon dynamics from decadal to millennial timescales. This project combines bulk and pool-specific radiocarbon analyses in the top and deep soil on a wide range of forested soils that span a large climatic gradient (MAT 1.3-9.2°C, MAP 600 to 2100 mm m-2y-1). These well-studies sites are part of the Long-Term Forest Ecosystem Research (LWF) program of the Swiss Federal Institute for Forest, Snow and Landscape research (WSL). This study aims to combine the insights gained from bulk and pool-specific turnover to environmental conditions and molecular composition of soil carbon. The pools investigated span the mineral-associated (occluded and heavy fractions from density fractionation) and potentially water-soluble (free light fractions from density fractionation and water extractable organic carbon) organic carbon fractions. Pool-specific radiocarbon work is augmented by the measurement of abundance of compounds such as alkanes, fatty acids and lignin phenols on a subset of samples. Initial results show disparate patterns depending on soil type and in particular soil texture, which could be indicative of various stabilization mechanisms in different soils. Overall, this study provides new insights into the controls of soil organic matter dynamics as related to environmental conditions, in particular in specific sub-pools of carbon.

  13. Dynamic replacement and loss of soil carbon on eroding cropland

    Science.gov (United States)

    Harden, J.W.; Sharpe, J.M.; Parton, W.J.; Ojima, D.S.; Fries, T.L.; Huntington, T.G.; Dabney, S.M.

    1999-01-01

    Links between erosion/sedimentation history and soil carbon cycling were examined in a highly erosive setting in Mississippi loess soils. We sampled soils on (relatively) undisturbed and cropped hillslopes and measured C, N, 14C, and CO2 flux to characterize carbon storage and dynamics and to parameterize Century and spreadsheet 14C models for different erosion and tillage histories. For this site, where 100 years of intensive cotton cropping were followed by fertilization and contour plowing, there was an initial and dramatic decline in soil carbon content from 1870 to 1950, followed by a dramatic increase in soil carbon. Soil erosion amplifies C loss and recovery: About 100% of the original, prehistoric soil carbon was likely lost over 127 years of intensive land use, but about 30% of that carbon was replaced after 1950. The eroded cropland was therefore a local sink for CO2 since the 1950s. However, a net CO2 sink requires a full accounting of eroded carbon, which in turn requires that decomposition rates in lower slopes or wetlands be reduced to about 20% of the upland value. As a result, erosion may induce unaccounted sinks or sources of CO2, depending on the fate of eroded carbon and its protection from decomposition. For erosion rates typical of the United States, the sink terms may be large enough (1 Gt yr-1, back-of-the-envelope) to warrant a careful accounting of site management, cropping, and fertilization histories, as well as burial rates, for a more meaningful global assessment.

  14. Explorations of soil microbial processes driven by dissolved organic carbon

    NARCIS (Netherlands)

    Straathof, A.L.

    2015-01-01

    Explorations of soil microbial processes driven by dissolved organic carbon Angela L. Straathof June 17, 2015, Wageningen UR ISBN 978-94-6257-327-7 Abstract Dissolved organic carbon (DOC) is a complex, heterogeneous mixture of C compounds which, as

  15. DETOXIFICATION OF PESTICIDES POLLUTED SOIL BY ADSORBTION ON ACTIVATED CARBONS

    Directory of Open Access Journals (Sweden)

    V.M. Mukhin

    2009-06-01

    Full Text Available The paper emphasizes a very severe social-ecological problem, related to the contamination of soils by pesticides and fodder micotoxins. The authors suggest the utilization of a carbon adsorption based method of purification of soils contaminated with traces of pesticides. It is demonstrated that this method of soil rehabilitation leads to an 80% crop increase, allowing the production of environmentally clean plant products. The utilization of special activated carbons “Ptitsesorb” leads to a 30-40% decrease of necessary combined fodder in chickens breeding.

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

    DEFF Research Database (Denmark)

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

    2010-01-01

    of SOC was lowest in the allophanic and chloritic soil, higher in the kaolinitic soils and highest in the smectitic soil. Our results contrast with conventional concepts of the greater capacity of smectite than of kaolinite to stabilize SOC. Contents of dithionite–citrate–bicarbonate extractable Fe...... stabilization in the kaolinitic soils. Our results suggest that the validity of predictive models of SOC turnover in tropical soils would be improved by the inclusion of soil types and contents of Fe and Al (hydr-) oxides.......Soil organic carbon (SOC) storage and turnover is influenced by interactions between organic matter and the mineral soil fraction. However, the influence of clay content and type on SOC turnover rates remains unclear, particularly in tropical soils under natural vegetation. We examined the lability...

  17. Molecular investigations into a globally important carbon pool: Permafrost-protected carbon in Alaskan soils

    Science.gov (United States)

    Waldrop, M.P.; Wickland, K.P.; White, Rickie; Berhe, A.A.; Harden, J.W.; Romanovsky, V.E.

    2010-01-01

    The fate of carbon (C) contained within permafrost in boreal forest environments is an important consideration for the current and future carbon cycle as soils warm in northern latitudes. Currently, little is known about the microbiology or chemistry of permafrost soils that may affect its decomposition once soils thaw. We tested the hypothesis that low microbial abundances and activities in permafrost soils limit decomposition rates compared with active layer soils. We examined active layer and permafrost soils near Fairbanks, AK, the Yukon River, and the Arctic Circle. Soils were incubated in the lab under aerobic and anaerobic conditions. Gas fluxes at -5 and 5 ??C were measured to calculate temperature response quotients (Q10). The Q10 was lower in permafrost soils (average 2.7) compared with active layer soils (average 7.5). Soil nutrients, leachable dissolved organic C (DOC) quality and quantity, and nuclear magnetic resonance spectroscopy of the soils revealed that the organic matter within permafrost soils is as labile, or even more so, than surface soils. Microbial abundances (fungi, bacteria, and subgroups: methanogens and Basidiomycetes) and exoenzyme activities involved in decomposition were lower in permafrost soils compared with active layer soils, which, together with the chemical data, supports the reduced Q10 values. CH4 fluxes were correlated with methanogen abundance and the highest CH4 production came from active layer soils. These results suggest that permafrost soils have high inherent decomposability, but low microbial abundances and activities reduce the temperature sensitivity of C fluxes. Despite these inherent limitations, however, respiration per unit soil C was higher in permafrost soils compared with active layer soils, suggesting that decomposition and heterotrophic respiration may contribute to a positive feedback to warming of this eco region. Published 2010. This article is a US Government work and is in the public domain in the

  18. Sensitivity analysis and calibration of a soil carbon model (SoilGen2 in two contrasting loess forest soils

    Directory of Open Access Journals (Sweden)

    Y. Y. Yu

    2013-01-01

    Full Text Available To accurately estimate past terrestrial carbon pools is the key to understanding the global carbon cycle and its relationship with the climate system. SoilGen2 is a useful tool to obtain aspects of soil properties (including carbon content by simulating soil formation processes; thus it offers an opportunity for both past soil carbon pool reconstruction and future carbon pool prediction. In order to apply it to various environmental conditions, parameters related to carbon cycle process in SoilGen2 are calibrated based on six soil pedons from two typical loess deposition regions (Belgium and China. Sensitivity analysis using the Morris method shows that decomposition rate of humus (kHUM, fraction of incoming plant material as leaf litter (frecto and decomposition rate of resistant plant material (kRPM are the three most sensitive parameters that would cause the greatest uncertainty in simulated change of soil organic carbon in both regions. According to the principle of minimizing the difference between simulated and measured organic carbon by comparing quality indices, the suited values of kHUM, (frecto and kRPM in the model are deduced step by step and validated for independent soil pedons. The difference of calibrated parameters between Belgium and China may be attributed to their different vegetation types and climate conditions. This calibrated model allows more accurate simulation of carbon change in the whole pedon and has potential for future modeling of carbon cycle over long timescales.

  19. Can Earthworm "mix up" Soil Carbon Budgets in Temperate Forests Under Elevated Carbon Dioxide?

    Science.gov (United States)

    Sánchez-de León, Y.; González-Meler, M.; Sturchio, N. C.; Wise, D. H.; Norby, R. J.

    2008-12-01

    The effects of global change on earthworms and their associated feedbacks on soil and ecosystem processes have been largely overlooked. We studied how the responses of a temperate deciduous forest to elevated carbon dioxide atmospheric concentrations (e[CO2]) influence earthworms and the soil processes affected by them. Our objectives were to: i) identify soil layers of active soil mixing under e[CO2] and current carbon dioxide atmospheric concentrations (c[CO2]) using fallout cesium (137Cs), ii) study how e[CO2] affects earthworm populations, iii) understand the relationship between soil mixing and earthworms at our study site, and iv) identify the implications of earthworm-mediated soil mixing for the carbon budget of a temperate forest. To study soil mixing, we measured vertical 137Cs activity in soil cores (0-24 cm depth) collected in replicated e[CO2] and c[CO2] sweetgum (Liquidambar styraciflua) plots (n = 2) in a Free Air CO2 Enrichment (FACE) ecosystem experiment at Oak Ridge National Laboratory. We measured earthworm density and fresh weight in the plots in areas adjacent to where soil cores were taken. Preliminary results on the vertical distribution of 137Cs in the c[CO2] treatments showed that higher 137Cs activity was located from 8-16 cm depth and no 137Cs activity was measured below 20 cm. In contrast, in the e[CO2] treatment, peak 137Cs activity was slightly deeper (10-18 cm), and 137Cs activity was still measured below 22 cm. Mean earthworm density was higher in e[CO2] than c[CO2] treatments (168 m-2 and 87 m-2, respectively; p = 0.046); earthworm fresh weights, however, did not differ significantly between treatments (32 g m-2 and 18 g m-2, respectively; p = 0.182). The 137Cs vertical distribution suggest that soil mixing occurs deeper in e[CO2] than in c[CO2] treatments, which is consistent with higher earthworm densities in e[CO2] than in c[CO2] treatments. Mixing deeper low carbon content soil with shallower high carbon soil may result in a

  20. Global Sequestration Potential of Increased Organic Carbon in Cropland Soils.

    Science.gov (United States)

    Zomer, Robert J; Bossio, Deborah A; Sommer, Rolf; Verchot, Louis V

    2017-11-14

    The role of soil organic carbon in global carbon cycles is receiving increasing attention both as a potentially large and uncertain source of CO 2 emissions in response to predicted global temperature rises, and as a natural sink for carbon able to reduce atmospheric CO 2 . There is general agreement that the technical potential for sequestration of carbon in soil is significant, and some consensus on the magnitude of that potential. Croplands worldwide could sequester between 0.90 and 1.85 Pg C/yr, i.e. 26-53% of the target of the "4p1000 Initiative: Soils for Food Security and Climate". The importance of intensively cultivated regions such as North America, Europe, India and intensively cultivated areas in Africa, such as Ethiopia, is highlighted. Soil carbon sequestration and the conservation of existing soil carbon stocks, given its multiple benefits including improved food production, is an important mitigation pathway to achieve the less than 2 °C global target of the Paris Climate Agreement.

  1. A Canadian upland forest soil profile and carbon stocks database.

    Science.gov (United States)

    Shaw, Cindy; Hilger, Arlene; Filiatrault, Michelle; Kurz, Werner

    2018-04-01

    "A Canadian upland forest soil profile and carbon stocks database" was compiled in phases over a period of 10 years to address various questions related to modeling upland forest soil carbon in a national forest carbon accounting model. For 3,253 pedons, the SITES table contains estimates for soil organic carbon stocks (Mg/ha) in organic horizons and mineral horizons to a 100-cm depth, soil taxonomy, leading tree species, mean annual temperature, annual precipitation, province or territory, terrestrial ecozone, and latitude and longitude, with an assessment of the quality of information about location. The PROFILES table contains profile data (16,167 records by horizon) used to estimate the carbon stocks that appear in the SITES table, plus additional soil chemical and physical data, where provided by the data source. The exceptions to this are estimates for soil carbon stocks based on Canadian National Forest Inventory data (NFI [2006] in REFERENCES table), where data were collected by depth increment rather than horizon and, therefore, total soil carbon stocks were calculated separately before being entered into the SITES table. Data in the PROFILES table include the carbon stock estimate for each horizon (corrected for coarse fragment content), and the data used to calculate the carbon stock estimate, such as horizon thickness, bulk density, and percent organic carbon. The PROFILES table also contains data, when reported by the source, for percent carbonate carbon, pH, percent total nitrogen, particle size distribution (percent sand, silt, clay), texture class, exchangeable cations, cation and total exchange capacity, and percent Fe and Al. An additional table provides references (REFERENCES table) for the source data. Earlier versions of the database were used to develop national soil carbon modeling categories based on differences in carbon stocks linked to soil taxonomy and to examine the potential of using soil taxonomy and leading tree species to improve

  2. Soil organic matter dynamics and the global carbon cycle

    International Nuclear Information System (INIS)

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

    1992-01-01

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

  3. The sensitivity of soil respiration to soil temperature, moisture, and carbon supply at the global scale.

    Science.gov (United States)

    Hursh, Andrew; Ballantyne, Ashley; Cooper, Leila; Maneta, Marco; Kimball, John; Watts, Jennifer

    2017-05-01

    Soil respiration (Rs) is a major pathway by which fixed carbon in the biosphere is returned to the atmosphere, yet there are limits to our ability to predict respiration rates using environmental drivers at the global scale. While temperature, moisture, carbon supply, and other site characteristics are known to regulate soil respiration rates at plot scales within certain biomes, quantitative frameworks for evaluating the relative importance of these factors across different biomes and at the global scale require tests of the relationships between field estimates and global climatic data. This study evaluates the factors driving Rs at the global scale by linking global datasets of soil moisture, soil temperature, primary productivity, and soil carbon estimates with observations of annual Rs from the Global Soil Respiration Database (SRDB). We find that calibrating models with parabolic soil moisture functions can improve predictive power over similar models with asymptotic functions of mean annual precipitation. Soil temperature is comparable with previously reported air temperature observations used in predicting Rs and is the dominant driver of Rs in global models; however, within certain biomes soil moisture and soil carbon emerge as dominant predictors of Rs. We identify regions where typical temperature-driven responses are further mediated by soil moisture, precipitation, and carbon supply and regions in which environmental controls on high Rs values are difficult to ascertain due to limited field data. Because soil moisture integrates temperature and precipitation dynamics, it can more directly constrain the heterotrophic component of Rs, but global-scale models tend to smooth its spatial heterogeneity by aggregating factors that increase moisture variability within and across biomes. We compare statistical and mechanistic models that provide independent estimates of global Rs ranging from 83 to 108 Pg yr -1 , but also highlight regions of uncertainty

  4. Effect of tree species on carbon stocks in forest floor and mineral soil and implications for soil carbon inventories

    NARCIS (Netherlands)

    Schulp, Catharina J E; Nabuurs, Gert Jan; Verburg, Peter H.; de Waal, Rein W.

    2008-01-01

    Forest soil organic carbon (SOC) and forest floor carbon (FFC) stocks are highly variable. The sampling effort required to assess SOC and FFC stocks is therefore large, resulting in limited sampling and poor estimates of the size, spatial distribution, and changes in SOC and FFC stocks in many

  5. Environmental analyse of soil organic carbon stock changes in Slovakia

    Science.gov (United States)

    Koco, Š.; Barančíková, G.; Skalský, R.; Tarasovičová, Z.; Gutteková, M.; Halas, J.; Makovníková, J.; Novákova, M.

    2012-04-01

    The content and quality of soil organic matter is one of the basic soil parameters on which soil production functioning depends as well as it is active in non production soil functions like an ecological one especially. Morphologic segmentation of Slovakia has significant influence of structure in using agricultural soil in specific areas of our territory. Also social changes of early 90´s of 20´th century made their impact on change of using of agricultural soil (transformation from large farms to smaller ones, decreasing the number of livestock). This research is studying changes of development of soil organic carbon stock (SOC) in agricultural soil of Slovakia as results of climatic as well as social and political changes which influenced agricultury since last 40 years. The main goal of this research is an analysis of soil organic carbon stock since 1970 until now at specific agroclimatic regions of Slovakia and statistic analysis of relation between modelled data of SOC stock and soil quality index value. Changes of SOC stock were evaluated on the basis SOC content modeling using RothC-26.3 model. From modeling of SOC stock results the outcome is that in that time the soil organic carbon stock was growing until middle 90´s years of 20´th century with the highest value in 1994. Since that year until new millennium SOC stock is slightly decreasing. After 2000 has slightly increased SOC stock so far. According to soil management SOC stock development on arable land is similar to overall evolution. In case of grasslands after slight growth of SOC stock since 1990 the stock is in decline. This development is result of transformational changes after 1989 which were specific at decreasing amount of organic carbon input from organic manure at grassland areas especially. At warmer agroclimatic regions where mollic fluvisols and chernozems are present and where are soils with good quality and steady soil organic matter (SOM) the amount of SOC in monitored time is

  6. LBA-ECO ND-08 Soil Respiration, Soil Fractions, Carbon and Nitrogen, Para, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set provides (1) carbon (C) and nitrogen (N) concentration measurements of two soil aggregate fractions (250-2000 micon, small macro-aggregates...

  7. Soil phosphorus does not keep pace with soil carbon and nitrogen accumulation following woody encroachment.

    Science.gov (United States)

    Zhou, Yong; Boutton, Thomas W; Wu, X Ben

    2018-05-01

    Soil carbon, nitrogen, and phosphorus cycles are strongly interlinked and controlled through biological processes, and the phosphorus cycle is further controlled through geochemical processes. In dryland ecosystems, woody encroachment often modifies soil carbon, nitrogen, and phosphorus stores, although it remains unknown if these three elements change proportionally in response to this vegetation change. We evaluated proportional changes and spatial patterns of soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) concentrations following woody encroachment by taking spatially explicit soil cores to a depth of 1.2 m across a subtropical savanna landscape which has undergone encroachment by Prosopis glandulosa (an N 2 fixer) and other woody species during the past century in southern Texas, USA. SOC and TN were coupled with respect to increasing magnitudes and spatial patterns throughout the soil profile following woody encroachment, while TP increased slower than SOC and TN in topmost surface soils (0-5 cm) but faster in subsurface soils (15-120 cm). Spatial patterns of TP strongly resembled those of vegetation cover throughout the soil profile, but differed from those of SOC and TN, especially in subsurface soils. The encroachment of woody species dominated by N 2 -fixing trees into this P-limited ecosystem resulted in the accumulation of proportionally less soil P compared to C and N in surface soils; however, proportionally more P accrued in deeper portions of the soil profile beneath woody patches where alkaline soil pH and high carbonate concentrations would favor precipitation of P as relatively insoluble calcium phosphates. This imbalanced relationship highlights that the relative importance of biotic vs. abiotic mechanisms controlling C and N vs. P accumulation following vegetation change may vary with depth. Our findings suggest that efforts to incorporate effects of land cover changes into coupled climate-biogeochemical models

  8. Stable isotopic constraints on global soil organic carbon turnover

    Directory of Open Access Journals (Sweden)

    C. Wang

    2018-02-01

    Full Text Available Carbon dioxide release during soil organic carbon (SOC turnover is a pivotal component of atmospheric CO2 concentrations and global climate change. However, reliably measuring SOC turnover rates on large spatial and temporal scales remains challenging. Here we use a natural carbon isotope approach, defined as beta (β, which was quantified from the δ13C of vegetation and soil reported in the literature (176 separate soil profiles, to examine large-scale controls of climate, soil physical properties and nutrients over patterns of SOC turnover across terrestrial biomes worldwide. We report a significant relationship between β and calculated soil C turnover rates (k, which were estimated by dividing soil heterotrophic respiration rates by SOC pools. ln( − β exhibits a significant linear relationship with mean annual temperature, but a more complex polynomial relationship with mean annual precipitation, implying strong-feedbacks of SOC turnover to climate changes. Soil nitrogen (N and clay content correlate strongly and positively with ln( − β, revealing the additional influence of nutrients and physical soil properties on SOC decomposition rates. Furthermore, a strong (R2 = 0.76; p < 0.001 linear relationship between ln( − β and estimates of litter and root decomposition rates suggests similar controls over rates of organic matter decay among the generalized soil C stocks. Overall, these findings demonstrate the utility of soil δ13C for independently benchmarking global models of soil C turnover and thereby improving predictions of multiple global change influences over terrestrial C-climate feedback.

  9. Clay Dispersibility and Soil Friability - Testing the Soil Clay-to-Carbon Saturation Concept

    DEFF Research Database (Denmark)

    Schjønning, Per; de Jonge, Lis Wollesen; Munkholm, Lars Juhl

    2012-01-01

    Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC...... as a predictor of clay dispersibility and soil friability. Soil was sampled 3 yr in a field varying in clay content (∼100 to ∼220 g kg−1 soil) and grown with different crop rotations. Clay dispersibility was measured after end-over-end shaking of field-moist soil and 1- to 2-mm sized aggregates either air......-dried or rewetted to −100 hPa matric potential. Tensile strength of 1- to 2-, 2- to 4-, 4- to 8-, and 8- to 16-mm air-dried aggregates was calculated from their compressive strength, and soil friability estimated from the strength–volume relation. Crop rotation characteristics gave only minor effects on clay...

  10. Soil Organic Carbon assessment on two different forest management

    Science.gov (United States)

    Fernández Minguillón, Alex; Sauras Yera, Teresa; Vallejo Calzada, Ramón

    2017-04-01

    Soil Organic Carbon assessment on two different forest management. A.F. Minguillón1, T. Sauras1, V.R: Vallejo1. 1 Departamento de Biología Evolutiva, Ecología y Ciencias Ambientales, Universidad de Barcelona, Avenida Diagonal 643, 03080 Barcelona, Spain. Soils from arid and semiarid zones are characterized by a low organic matter content from scarce plant biomass and it has been proposed that these soils have a big capacity to carbon sequestration. According to IPCC ARS WG2 (2014) report and WG3 draft, increase carbon storage in terrestrial ecosystems has been identified such a potential tool for mitigation and adaptation to climate change. In ecological restoration context improve carbon sequestration is considered a management option with multiple benefits (win-win-win). Our work aims to analyze how the recently developed restoration techniques contributed to increases in terrestial ecosystem carbon storage. Two restoration techniques carried out in the last years have been evaluated. The study was carried out in 6 localities in Valencian Community (E Spain) and organic horizons of two different restoration techniques were evaluated; slash brush and thinning Aleppo pine stands. For each technique, carbon stock and its physical and chemical stability has been analysed. Preliminary results point out restoration zones acts as carbon sink due to (1) the relevant necromass input produced by slash brush increases C stock on the topsoil ;(2) Thinning increase carbon accumulation in vegetation.

  11. Soil carbon distribution in Alaska in relation to soil-forming factors

    Science.gov (United States)

    Kristofer D. Johnson; Jennifer Harden; A. David McGuire; Norman B. Bliss; James G. Bockheim; Mark Clark; Teresa Nettleton-Hollingsworth; M. Torre Jorgenson; Evan S. Kane; Michelle Mack; Johathan ODonnell; Chien-Lu Ping; Edward A.G. Schuur; Merritt R. Turetsky; David W. Valentine

    2011-01-01

    The direction and magnitude of soil organic carbon (SOC) changes in response to climate change remain unclear and depend on the spatial distribution of SOC across landscapes. Uncertainties regarding the fate of SOC are greater in high-latitude systems where data are sparse and the soils are affected by sub-zero temperatures. To address these issues in Alaska, a first-...

  12. Abundant and stable char residues in soils: Implications for soil fertility and carbon sequestration

    Science.gov (United States)

    Large-scale soil application of biochar might enhance soil fertility and increase crop production, while also sequestering atmospheric carbon. Reaching these outcomes requires an undertanding of the chemical structure of biochar. Using advanced solid-state 13C nuclear magnetic resonance spectroscopy...

  13. Spatial patterns of soil organic carbon stocks in Estonian arable soils

    Science.gov (United States)

    Suuster, Elsa; Astover, Alar; Kõlli, Raimo; Roostalu, Hugo; Reintam, Endla; Penu, Priit

    2010-05-01

    Soil organic carbon (SOC) determines ecosystem functions, influencing soil fertility, soil physical, chemical and biological properties and crop productivity. Therefore the spatial pattern of SOC stocks and its appropriate management is important at various scales. Due to climate change and the contribution of carbon store in the soils, the national estimates of soil carbon stocks should be determined. Estonian soils have been well studied and mapped at a scale 1:10,000. Previous studies have estimated SOC stocks based on combinations of large groups of Estonian soils and the mean values of the soil profile database, but were not embedded into the geo-referenced databases. These studies have estimated SOC stocks of Estonian arable soils 122.3 Tg. Despite of available soil maps and databases, this information is still very poorly used for spatial soil modelling. The aim of current study is to assess and model spatial pattern of SOC stocks of arable soils on a pilot area Tartu County (area 3089 sq km). Estonian digital soil map and soil monitoring databases are providing a good opportunity to assess SOC stocks at various scales. The qualitative nature of the initial data from a soil map prohibits any straightforward use in modelling. Thus we have used several databases to construct models and linkages between soil properties that can be integrated into soil map. First step was to reorganize the soil map database (44,046 mapping units) so it can be used as an input to modelling. Arable areas were distinguished by a field layer of Agricultural Registers and Information Board, which provides precise information of current land use as it is the basis of paying CAP subsidies. The estimates of SOC content were found by using the arable land evaluation database of Tartu from the Estonian Land Board (comprising 950 sq km and 31,226 fields), where each soil type was assessed separately and average SOC content grouped by texture was derived. SOC content of epipedon varies in

  14. 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.

  15. Climate legacies drive global soil carbon stocks in terrestrial ecosystems.

    Science.gov (United States)

    Delgado-Baquerizo, Manuel; Eldridge, David J; Maestre, Fernando T; Karunaratne, Senani B; Trivedi, Pankaj; Reich, Peter B; Singh, Brajesh K

    2017-04-01

    Climatic conditions shift gradually over millennia, altering the rates at which carbon (C) is fixed from the atmosphere and stored in the soil. However, legacy impacts of past climates on current soil C stocks are poorly understood. We used data from more than 5000 terrestrial sites from three global and regional data sets to identify the relative importance of current and past (Last Glacial Maximum and mid-Holocene) climatic conditions in regulating soil C stocks in natural and agricultural areas. Paleoclimate always explained a greater amount of the variance in soil C stocks than current climate at regional and global scales. Our results indicate that climatic legacies help determine global soil C stocks in terrestrial ecosystems where agriculture is highly dependent on current climatic conditions. Our findings emphasize the importance of considering how climate legacies influence soil C content, allowing us to improve quantitative predictions of global C stocks under different climatic scenarios.

  16. Carbon Sequestration in Reclaimed Mined Soils of Ohio

    Energy Technology Data Exchange (ETDEWEB)

    K. Lorenz; R. Lal

    2007-12-31

    This research project was aimed at assessing the soil organic carbon (SOC) sequestration potential of reclaimed minesoils (RMS). The experimental sites were characterized by distinct age chronosequences of RMS and were located in Guernsey, Morgan, Noble, and Muskingum Counties of Ohio. Restoration of disturbed land is followed by the application of nutrients to the soil to promote the vegetation development. Reclamation is important both for preserving the environmental quality and increasing agronomic yields. Since reclamation treatments have significant influence on the rate of soil development, a study on subplots was designed with the objectives of assessing the potential of different biosolids on soil organic C (SOC) sequestration rate, soil development, and changes in soil physical and water transmission properties. All sites are owned and maintained by American Electric Power (AEP). These sites were reclaimed by two techniques: (1) with topsoil application, and (2) without topsoil application, and were under continuous grass or forest cover.

  17. Global patterns in mangrove soil carbon stocks and losses

    Science.gov (United States)

    Atwood, Trisha B.; Connolly, Rod M.; Almahasheer, Hanan; Carnell, Paul E.; Duarte, Carlos M.; Ewers Lewis, Carolyn J.; Irigoien, Xabier; Kelleway, Jeffrey J.; Lavery, Paul S.; Macreadie, Peter I.; Serrano, Oscar; Sanders, Christian J.; Santos, Isaac; Steven, Andrew D. L.; Lovelock, Catherine E.

    2017-07-01

    Mangrove soils represent a large sink for otherwise rapidly recycled carbon (C). However, widespread deforestation threatens the preservation of this important C stock. It is therefore imperative that global patterns in mangrove soil C stocks and their susceptibility to remineralization are understood. Here, we present patterns in mangrove soil C stocks across hemispheres, latitudes, countries and mangrove community compositions, and estimate potential annual CO2 emissions for countries where mangroves occur. Global potential CO2 emissions from soils as a result of mangrove loss were estimated to be ~7.0 Tg CO2e yr-1. Countries with the highest potential CO2 emissions from soils are Indonesia (3,410 Gg CO2e yr-1) and Malaysia (1,288 Gg CO2e yr-1). The patterns described serve as a baseline by which countries can assess their mangrove soil C stocks and potential emissions from mangrove deforestation.

  18. Global patterns in mangrove soil carbon stocks and losses

    KAUST Repository

    Atwood, Trisha B.

    2017-06-26

    Mangrove soils represent a large sink for otherwise rapidly recycled carbon (C). However, widespread deforestation threatens the preservation of this important C stock. It is therefore imperative that global patterns in mangrove soil C stocks and their susceptibility to remineralization are understood. Here, we present patterns in mangrove soil C stocks across hemispheres, latitudes, countries and mangrove community compositions, and estimate potential annual CO2 emissions for countries where mangroves occur. Global potential CO2 emissions from soils as a result of mangrove loss were estimated to be ~7.0 Tg CO2e yr−1. Countries with the highest potential CO2 emissions from soils are Indonesia (3,410 Gg CO2e yr−1) and Malaysia (1,288 Gg CO2e yr−1). The patterns described serve as a baseline by which countries can assess their mangrove soil C stocks and potential emissions from mangrove deforestation.

  19. One strategy for estimating the potential soil carbon storage due to CO2 fertilization

    International Nuclear Information System (INIS)

    Harrison, K.G.; Bonani, G.

    1994-01-01

    Soil radiocarbon measurements can be used to estimate soil carbon turnover rates and inventories. A labile component of soil carbon has the potential to respond to perturbations such as CO 2 fertilization, changing climate, and changing land use. Soil carbon has influenced past and present atmospheric CO 2 levels and will influence future levels. A model is used to calculate the amount of additional carbon stored in soil because of CO 2 fertilization

  20. [Variation characteristics of soil carbon sequestration under long-term different fertilization in red paddy soil].

    Science.gov (United States)

    Huang, Jing; Zhang, Yang-zhu; Gao, Ju-sheng; Zhang, Wen-ju; Liu, Shu-jun

    2015-11-01

    The objective of this study was to clarify the changes of soil organic carbon (SOC) content, the saturation capacity of soil carbon sequestration and its cooperation with carbon input (crop source and organic fertilizer source carbon) under long-term (1982-2012) different fertilization in red paddy soil. The results showed that fertilization could increase SOC content. The SOC content of all the fertilization treatments demonstrated a trend of stabilization after applying fertilizer for 30 years. The SOC content in the treatments applying organic manure with mineral fertilizers was between 21.02 and 21.24 g · kg(-1), and the increase rate ranged from 0.41 to 0.59 g · kg(-1) · a(-1). The SOC content in the treatments applying mineral fertilizers only was 15.48 g · kg(-1). The average soil carbon sequestration in the treatments that applied organic manure with mineral fertilizers ranged from 43.61 to 48.43 t C · hm(-2), and the average SOC storage over the years in these treatments was significantly greater than those applying mineral fertilizers only. There was an exponentially positive correlation between C sequestration efficiency and annual average organic C input. It must input exogenous organic carbon at least at 0. 12 t C · hm(-2) · a(-1) to maintain the balance of soil organic carbon under the experimental conditions.

  1. Soil carbon sequestration and biochar as negative emission technologies.

    Science.gov (United States)

    Smith, Pete

    2016-03-01

    Despite 20 years of effort to curb emissions, greenhouse gas (GHG) emissions grew faster during the 2000s than in the 1990s, which presents a major challenge for meeting the international goal of limiting warming to carbon capture and storage and afforestation/deforestation, showed that all NETs have significant limits to implementation, including economic cost, energy requirements, land use, and water use. In this paper, I assess the potential for negative emissions from soil carbon sequestration and biochar addition to land, and also the potential global impacts on land use, water, nutrients, albedo, energy and cost. Results indicate that soil carbon sequestration and biochar have useful negative emission potential (each 0.7 GtCeq. yr(-1) ) and that they potentially have lower impact on land, water use, nutrients, albedo, energy requirement and cost, so have fewer disadvantages than many NETs. Limitations of soil carbon sequestration as a NET centre around issues of sink saturation and reversibility. Biochar could be implemented in combination with bioenergy with carbon capture and storage. Current integrated assessment models do not represent soil carbon sequestration or biochar. Given the negative emission potential of SCS and biochar and their potential advantages compared to other NETs, efforts should be made to include these options within IAMs, so that their potential can be explored further in comparison with other NETs for climate stabilization. © 2016 John Wiley & Sons Ltd.

  2. Use of Carbon Isotopic Tracers in Investigating Soil Carbon Sequestration and Stabilization in Agroecosystems

    International Nuclear Information System (INIS)

    2017-09-01

    The global surface temperatures have been reported to increase at an average rate of 0.06 C (0.11 F) per decade. This observed climate change known as the greenhouse effect is attributed to the emission of greenhouse gases (GHGs), including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) to the atmosphere, resulting in trapping the heat near the earth’s surface causing global warming. World soils are the largest reservoir of terrestrial carbon and that soils are a source or sink of GHGs depending on land use management. Recognizing the urgent need to address the soil organic matter constraints for a sustainable agricultural production to ensure food security, this publication provides an integrated view on conventional and isotopic methods of measuring and modelling soil carbon dynamics, and the use nuclear and radioisotope tracer techniques in in-situ glasshouse and field labelling techniques to assess soil organic matter turnover and sequestration.

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

    Science.gov (United States)

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

    2016-04-01

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

  4. Functional soil organic carbon pools for major soil units and land uses in southern Germany

    Science.gov (United States)

    Kögel-Knabner, Ingrid; Wiesmeier, Martin

    2015-04-01

    Soil management, especially the type and intensity of land use, affect the carbon cycle to a high extent as they modify carbon sequestration in a specific soil. Thus man is intervening in the natural carbon cycle on a global scale. In our study, the amount of active, intermediate and passive SOC pools was determined for major soil types and land uses of Bavaria in southern Germany. Our SOC inventory revealed only slightly lower total SOC stocks in cropland soils compared to forest soils, when both top- and subsoils were considered. In cropland and grassland soils around 90% of total SOC stocks can be assigned to the intermediate and passive SOC pool. High SOC stocks in grassland soils are partly related to a higher degree of soil aggregation compared to cropland soils. The contribution of intermediate SOC in cropland soils was similar to that in grassland soils due to an increased proportion of SOM associated with silt and clay particles. The cultivation-induced loss of SOC due to aggregate disruption is at least partly compensated by increased formation of organo-mineral associations as a result of tillage that continuously promotes the contact of crop residues with reactive mineral surfaces. Contrary, forest soils were characterized by distinctly lower proportions of intermediate and passive SOC and a high amount of active SOC in form of litter and particulate organic matter which accounted for almost 40% of total SOC stocks. The determination of the current SOC content of silt and clay fractions for major soil units and land uses allowed an estimation of the C saturation deficit corresponding to the long-term C sequestration potential. The results showed that cropland soils have a low level of C saturation of around 50% and could store considerable amounts of additional SOC. A relatively high C sequestration potential was also determined for grassland soils. In contrast, forest soils had a low C sequestration potential as they were almost C saturated. The high

  5. Contrasting effects of repeated summer drought on soil carbon efflux in hydric and mesic heathland soils

    NARCIS (Netherlands)

    Sowerby, A.; Emmett, B.A.; Tietema, A.; Beier, C.

    2008-01-01

    Current predictions of climate change include altered rainfall patterns throughout Europe, continental USA and areas such as the Amazon. The effect of this on soil carbon efflux remains unclear although several modelling studies have highlighted the potential importance of drought for carbon

  6. [Distribution of soil organic carbon storage and carbon density in Gahai Wetland ecosystem].

    Science.gov (United States)

    Ma, Wei-Wei; Wang, Hui; Huang, Rong; Li, Jun-Zhen; Li, De-Yu

    2014-03-01

    The profile distribution and accumulation characteristics of organic carbon of four typical marshes (herbaceous peat, marsh wetland, mountain wetland, subalpine meadow) were studied in Gahai Wetlands of Gannan in July 2011. The results showed that the soil bulk densities of the four typical marshes ranged from 0.22 to 1.29 g x cm(-3). The content of soil organic carbon in the herbaceous peat was higher than in other types, with its average content of organic carbon (286. 80 g x kg(-1)) being about 2.91, 4.99, 7.31 times as much as that of the marsh wetland, mountain wetland and subalpine meadow, respectively. The average organic carbon densities were in order of herbaceous peat > subalpine meadow > marsh wetland > mountain wetland, with the highest in the 0-10 cm layer. The change of organic carbon density along the soil profile was basically in accordance with the organic carbon content in the four typical marshes, but fluctuated with soil depth. There were obviously two carbon storage layers (0-10 and 20-40 cm, respectively) in the four typical marshes. The amounts of organic carbon stored in the 0-60 cm layer of the four typical marshes were 369.46, 278.83, 276.16, 292.23 t x hm(-2), respectively. The total amount of organic carbon stored in the 0-60 cm of the four typical marshes was about 9.50 x 10(6) t.

  7. Increased Carbon Throughput But No Net Soil Carbon Loss in Field Warming Experiments: Combining Data Assimilation and Meta-Analyses

    Science.gov (United States)

    van Gestel, N.; Shi, Z.; van Groenigen, K. J.; Osenberg, C. W.; Andresen, L. C.; Dukes, J. S.; Hovenden, M. J.; Michelsen, A.; Pendall, E.; Reich, P.; Schuur, E.; Hungate, B. A.

    2017-12-01

    Minor changes in soil C dynamics in response to warming can strongly modulate climate change. Approaches to estimate long-term changes in soil carbon stocks from shorter-term warming experiments should consider temporal trends in soil carbon dynamics. Here we used data assimilation to take into account the soil carbon time series data collected from the upper soil layer (materials. We show that on average experimental warming enhanced fluxes of incoming and outgoing carbon with no change in predicted equilibrium stocks of carbon. Experimental warming increased the decomposition rates of the fast soil carbon pools by 10.7% on average, but also increased soil carbon input by 8.1%. When projecting the carbon pools to equilibrium stocks we found that warming decreased the size of the fast pool (-3.7%), but did not affect the slow or total carbon pools. We demonstrate that warming increases carbon throughput without an overall effect on total equilibrium carbon stocks. Hence, our findings do not support a generalizable soil carbon-climate feedback for soil carbon in the upper soil layer.

  8. Monitoring and verifying changes of organic carbon in soil

    Science.gov (United States)

    Post, W.M.; Izaurralde, R. C.; Mann, L. K.; Bliss, Norman B.

    2001-01-01

    Changes in soil and vegetation management can impact strongly on the rates of carbon (C) accumulation and loss in soil, even over short periods of time. Detecting the effects of such changes in accumulation and loss rates on the amount of C stored in soil presents many challenges. Consideration of the temporal and spatial heterogeneity of soil properties, general environmental conditions, and management history is essential when designing methods for monitoring and projecting changes in soil C stocks. Several approaches and tools will be required to develop reliable estimates of changes in soil C at scales ranging from the individual experimental plot to whole regional and national inventories. In this paper we present an overview of soil properties and processes that must be considered. We classify the methods for determining soil C changes as direct or indirect. Direct methods include field and laboratory measurements of total C, various physical and chemical fractions, and C isotopes. A promising direct method is eddy covariance measurement of CO2 fluxes. Indirect methods include simple and stratified accounting, use of environmental and topographic relationships, and modeling approaches. We present a conceptual plan for monitoring soil C changes at regional scales that can be readily implemented. Finally, we anticipate significant improvements in soil C monitoring with the advent of instruments capable of direct and precise measurements in the field as well as methods for interpreting and extrapolating spatial and temporal information.

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

    Science.gov (United States)

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

    2006-01-01

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

  10. Pedogenetic processes and carbon budgets in soils of Queretaro, Mexico

    Science.gov (United States)

    García Calderón, Norma Eugenia; Fuentes Romero, Elizabeth; Hernandez Silva, Gilberto

    2014-05-01

    Pedogenetic processes have been investigated in two different physiographic regions of the state of Querétaro in order to assess the carbon budget of soils, looking into the gains and losses of organic and inorganic carbon: In the mountain region of the natural reserve Sierra Gorda (SG) with soils developed on cretaceous argillites and shales under sub-humid temperate to semi-arid conditions, and in the Transmexican Volcanic Belt (TMVB) with soils developed on acid and intermediate igneous rocks under humid temperate climate in the highlands and semi-arid and subhumid subtropical conditions in the lowlands. The analyses of soil organic carbon (SOC) and soil inorganic carbon (SIC) of the SG region, including additional physical, chemical and mineralogical investigations were based on 103 topsoils in an area of 170 km2. The analyses in the TMVB region were based on the profiles of a soil toposequence from high mountainous positions down to the plains of the lowlands. The results show a SOC accumulation from temperate to semi-arid forest environments, based on processes of humification and clay formation including the influence of exchangeable Ca and the quantity and quality of clay minerals. The turnover rates of SOC and SIC depended largely on the rock parent materials, especially the presence of carbonate rocks. Moreover, we found that the SOC content and distribution was clearly depending on land use, decreasing from forests to agricultural land, such as pasture and cropping areas and were lowest under mining sites. The highest SIC pools were found in accumulation horizons of soils under semi-arid conditions. On all investigated sites SOC decreased the mobility of cations and especially that of heavy metals, such as As, Hg, Sb, Pb, and Cd.

  11. Regional prediction of carbon isotopes in soil carbonates for Asian dust source tracer

    Science.gov (United States)

    Chen, Bing; Cui, Xinjuan; Wang, Yaqiang

    2016-10-01

    Dust particles emitted from deserts and semi-arid lands in northern China cause particulate pollution that increases the burden of disease particularly for urban population in East Asia. The stable carbon isotopes (δ13C) of carbonates in soils and dust aerosols in northern China were investigated. We found that the δ13C of carbonates in surface soils in northern China showed clearly the negative correlation (R2 = 0.73) with Normalized Difference Vegetation Index (NDVI). Using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite-derived NDVI, we predicted the regional distribution of δ13C of soil carbonates in deserts, sandy lands, and steppe areas. The predictions show the mean δ13C of -0.4 ± 0.7‰ in soil carbonates in Taklimakan Desert and Gobi Deserts, and the isotope values decrease to -3.3 ± 1.1‰ in sandy lands. The increase in vegetation coverage depletes 13C in soil carbonates, thus the steppe areas are predicted by the lowest δ13C levels (-8.1 ± 1.7‰). The measurements of atmospheric dust samples at eight sites showed that the Asian dust sources were well assigned by the 13C mapping in surface soils. Predicting 13C in large geographical areas with fine resolution offers a cost-effective tracer to monitor dust emissions from sandy lands and steppe areas which show an increasing role in Asian dust loading driven by climate change and human activities.

  12. [Effects of Green Manure Intercropping and Straw Mulching on Winter Rape Rhizosphere Soil Organic Carbon and Soil Respiration].

    Science.gov (United States)

    Zhou, Quan; Wang, Long-chang; Xiong, Ying; Zhang, Sai; Du, Juan; Zhao, Lin-lu

    2016-03-15

    Under the background of global warming, the farmland soil respiration has become the main way of agricultural carbon emissions. And green manure has great potential to curb greenhouse gas emissions and achieve energy conservation and emissions reduction. However, in purple soil region of Southwest, China, soil respiration under green manure remains unclear, especially in the winter and intercropping. Through the green manure ( Chinese milk vetch) intercropping with rape, therefore, we compared the effects of rape rhizosphere under straw mulching. The soil organic carbon and soil respiration were examined. The results showed, compared with straw mulching, root separation was the major influencing factors of soil organic carbon on rape rhizosphere. Soil organic carbon was significantly decreased by root interaction. In addition, straw mulching promoted while green manure intercropping inhibited the soil respiration. Soil respiration presented the general characteristics of fall-rise-fall due to the strong influence of rape growth period. Therefore, it showed a cubic curve relationship with soil temperature.

  13. Human induced impacts on soil organic carbon in southwest Iceland

    Science.gov (United States)

    Gísladóttir, Guðrún; Erlendsson, Egill; Lal, Rattan

    2013-04-01

    The Icelandic environment has been strongly influenced by natural processes during the Holocene. Since settlement in AD 874, the introduction of grazing animals and other land use has drastically affected the natural environment. This includes the diminishing of vegetative cover, which has led to soil exposure and accelerated erosion over large areas, especially when in conjunction with harsh climate. This has specifically impacted processes and properties of volcanic soils (Andosols), which are subject to accelerated erosion by wind and water. While approximately 46% of the land surface in Iceland has sustained continuous vegetation cover, large areas have lost some or all of their soil cover formed during the postglacial era. Elsewhere, remaining soils have sparse or no vegetation cover, thus impairing soil carbon (C) sequestration. Among their multifunctional roles, soils support plant growth, increase soil biotic activity, enhance nutrient storage and strengthen the cycling of water and nutrients. In contrast, soil degradation by accelerated erosion and other processes impairs soil quality, reduces soil structure and depletes the soil organic matter (SOM) pool. Depletion of the SOM pool has also global implications because the terrestrial C pool is the third largest pool and strongly impacts the global C cycle. Erosional-depositional processes may deplete soil organic C (SOC) by erosion and increase by deposition. Some SOC-enriched sediments are redistributed over the landscape, while others are deposited in depression sites and transported into aquatic ecosystems. SOC decomposition processes are severely constrained in some environmental settings and any SOC buried under anaerobic conditions is protected against decomposition. Yet, the impact of the SOC transported by erosional processes and redistributed over the landscape is not fully understood because the variability in its turnover characteristics has not been widely studied. Thus, the fate of C

  14. Distinguishing "new" from "old" carbon in post mining soils

    Science.gov (United States)

    Vindušková, Olga; Frouz, Jan

    2014-05-01

    Introduction Soils developing on heaped overburden after open pit coal mining near Sokolov, Czech Republic, provide an exceptional opportunity to study sites of different ages (0-70 years) developing on similar substrate under relatively well-known conditions. Soil organic carbon (SOC) is an useful indicator of soil quality and represents an important global carbon pool. Post-mining soils would be a perfect model for long-term study of carbon dynamics. Unfortunately, quantifying SOC in Sokolov post-mining soils is quite complicated, since conventional quantification methods cannot distinguish between SOC derived from plant residues and fossil organic carbon derived from coal and kerogen present in the overburden. Moreover, also inorganic carbon may sometimes bias SOC quantification. Up to now, the only way to directly estimate recently derived SOC in these soils is radiocarbon dating (Rumpel et al. 1999; Karu et al. 2009). However, this method is costly and thus cannot be used routinely. The aim of our study is to find an accessible method to quantify recently derived SOC. We would highly appreciate ideas of other soil scientists, organic geochemists and sedimentologists on how to solve this challenge. Methods and hypotheses A set of 14 soil samples were analysed by radiocarbon (14C-AMS) analysis, near-infrared spectroscopy (NIRS), 13C CPMAS NMR spectroscopy, Rock-Eval and XRD. For calibration of NIRS, also 125 artificial mixtures were produced by mixing different amounts of claystone, coal and partially decomposed litter. NIRS (1000-2500 nm) as well as younger mid-infrared spectroscopy has been widely applied to soils (Janik et al. 2007; Vasques et al. 2009; Michel et al. 2009). When combined with multivariate chemometric techniques, it can be used to predict concentration of different compounds. No study has yet focused on NIRS application to soils where fossil carbon is found in two chemically different forms - whereas coal is rather aromatic, kerogen in our

  15. Holocene carbon stocks and carbon accumulation rates altered in soils undergoing permafrost thaw

    Science.gov (United States)

    Caitlin E. Hicks Pries; Edward A.G. Schuur; K. Grace Crummer

    2012-01-01

    Permafrost soils are a significant global store of carbon (C) with the potential to become a large C source to the atmosphere. Climate change is causing permafrost to thaw, which can affect primary production and decomposition, therefore affecting ecosystem C balance. We modeled decadal and millennial soil C inputs, decomposition constants, and C accumulation rates by...

  16. Predicting Spatial Variability of Soil Organic Carbon in Delmarva Bays

    OpenAIRE

    Blumenthal, Kinsey Megan

    2016-01-01

    Agricultural productivity, ecosystem health, and wetland restoration rely on soil organic carbon (SOC) as vital for microbial activity and plant health. This study assessed: (1) accuracy of topographic-based non-linear models for predicting SOC; and (2) the effect of analytic strategies and soil condition on performance of spectral-based models for predicting SOC. SOC data came from 28 agriculturally converted Delmarva Bays sampled down to 1 meter. R2 was used as an indicator of model perform...

  17. Sampling for Soil Carbon Stock Assessment in Rocky Agricultural Soils

    Science.gov (United States)

    Beem-Miller, Jeffrey P.; Kong, Angela Y. Y.; Ogle, Stephen; Wolfe, David

    2016-01-01

    Coring methods commonly employed in soil organic C (SOC) stock assessment may not accurately capture soil rock fragment (RF) content or soil bulk density (rho (sub b)) in rocky agricultural soils, potentially biasing SOC stock estimates. Quantitative pits are considered less biased than coring methods but are invasive and often cost-prohibitive. We compared fixed-depth and mass-based estimates of SOC stocks (0.3-meters depth) for hammer, hydraulic push, and rotary coring methods relative to quantitative pits at four agricultural sites ranging in RF content from less than 0.01 to 0.24 cubic meters per cubic meter. Sampling costs were also compared. Coring methods significantly underestimated RF content at all rocky sites, but significant differences (p is less than 0.05) in SOC stocks between pits and corers were only found with the hammer method using the fixed-depth approach at the less than 0.01 cubic meters per cubic meter RF site (pit, 5.80 kilograms C per square meter; hammer, 4.74 kilograms C per square meter) and at the 0.14 cubic meters per cubic meter RF site (pit, 8.81 kilograms C per square meter; hammer, 6.71 kilograms C per square meter). The hammer corer also underestimated rho (sub b) at all sites as did the hydraulic push corer at the 0.21 cubic meters per cubic meter RF site. No significant differences in mass-based SOC stock estimates were observed between pits and corers. Our results indicate that (i) calculating SOC stocks on a mass basis can overcome biases in RF and rho (sub b) estimates introduced by sampling equipment and (ii) a quantitative pit is the optimal sampling method for establishing reference soil masses, followed by rotary and then hydraulic push corers.

  18. Predicting soil organic carbon at field scale using a national soil spectral library

    DEFF Research Database (Denmark)

    Peng, Yi; Knadel, Maria; Gislun, Rene

    2013-01-01

    Visible and near infrared diffuse reflectance (vis-NIR) spectroscopy is a low-cost, efficient and accurate soil analysis technique and is thus becoming increasingly popular. Soil spectral libraries are commonly constructed as the basis for estimating soil texture and properties. In this study......, partial least squares regression was used to develop models to predict the soil organic carbon (SOC) content of 35 soil samples from one field using (i) the Danish soil spectral library (2688 samples), (ii) a spiked spectral library (a combination of 30 samples selected from the local area...... and the spectral library, 2718 samples) and (iii) three sub-sets selected from the spectral library. In an attempt to improve prediction accuracy, sub-sets of the soil spectral library were made using three different sample selection methods: those geographically closest (84 samples), those with the same landscape...

  19. Value of Soil Organic Carbon in Agricultural Lands

    Energy Technology Data Exchange (ETDEWEB)

    Wander, M.; Nissen, T. [Department of Natural Resources and Environmental Sciences, University of Illinois, 1102 S. Goodwin Ave. Urbana IL 61801 (United States)

    2004-10-01

    Immediate efforts to increase soil carbon sequestration and minimize terrestrial greenhouse gas emissions are needed to mitigate global warming. Whether or not terrestrial stocks become sinks or net sources of C over the next century will depend upon how fast and at what level we are able to stabilize carbon dioxide levels. The cost of soil C sequestration is at present relatively low compared to other C emission reduction technologies making soil C sinks an important short-term solution to be used while competing technologies are developed. However, efforts to use C sequestration in soils as CO2 emissions offsets have faced numerous challenges. Difficulties associated with C stock validation (direct measurement) and the impermanence and saturability of soil C reservoirs raise concerns over whether soil C reservoirs are good long-term investments. Pragmatism has led to the development of indirect inventorying of the C reserves held at national and regional scales. Such indirect accounting systems will advance as validation methods are refined and as process models improve their ability to accurately predict how existing soil condition and specific land management practices will influence soil C storage and NO2 and CH4 emissions. Improved documentation of the value of environmental services and sustained productive potential derived from optimized land use and associated increases in soil quality will also add to the estimated value of soil C sinks. Policies must evolve simultaneously with the theoretical and technical tools needed to promote optimization of land use practices to mitigate climate change now and to minimize future contributions of soil C to atmospheric CO2.

  20. Soil Carbon in North American, Arctic, and Boreal Regions

    Science.gov (United States)

    Lajtha, K.; Bailey, V. L.; Schuur, E.; McGuire, D.; Romanovsky, V. E.

    2017-12-01

    Globally, soils contain more than 3 times as much as C as the atmosphere and >4 times more C than the world's biota, therefore even small changes in soil C stocks could lead to large changes in the atmospheric concentration of CO2. Since SOCCR-1, improvements have been made in quantifying stocks and uncertainties in stocks of soil C to a depth of 1 m across North America. Estimates for soil carbon stocks in the US (CONUS + Alaska) range from 151 - 162 Pg C, based on extensive sampling and analysis. Estimates for Canada average about 262 Pg C, but sampling is not as extensive. Soil C for Mexico is calculated as 18 Pg C, but there is a great deal of uncertainty surrounding this value. These soil carbon stocks are sensitive to agricultural management, land use and land cover change, and development and loss of C-rich soils such as wetlands. Climate change is a significant threat although may be partially mitigated by increased plant production. Carbon stored in permafrost zone circumpolar soils is equal to 1330-1580 Pg C, almost twice that contained in the atmosphere and about order of magnitude greater than carbon contained in plant biomass, woody debris, and litter in the boreal and tundra biomes combined. Surface air temperature change is amplified in high latitude regions such that Arctic temperature rise is about 2.5 times faster than for the globe as a whole, and thus 5 - 15% of this carbon is considered vulnerable to release to the atmosphere by the year 2100 following the current trajectory of global and Arctic warming. This amount is likely to be up to an order of magnitude larger loss than the increase in carbon stored in plant biomass under the same changing conditions. Models of soil organic matter dynamics have been greatly improved in the last decade by including greater process-level understanding of factors that affect soil C stabilization and destabilization, yet structural features of many models are still limited in representing Arctic and boreal

  1. Carbon stabilization mechanisms in soils in the Andes

    Science.gov (United States)

    Jansen, Boris; Cammeraat, Erik

    2015-04-01

    The volcanic ash soils of the Andes contain very large stocks of soil organic matter (SOM) per unit area. Consequently, they constitute significant potential sources or sinks of the greenhouse gas CO2. Climate and/or land use change potentially have a strong effect on these large SOM stocks. To clarify the role of chemical and physical stabilisation mechanisms in volcanic ash soils in the montane tropics, we investigated carbon stocks and stabilization mechanisms in the top- and subsoil along an altitudinal transect in the Ecuadorian Andes. The transect encompassed a sequence of paleosols under forest and grassland (páramo), including a site where vegetation cover changed in the last century. We applied selective extraction techniques, performed X-ray diffraction analyses of the clay fraction and estimated pore size distributions at various depths in the top- and subsoil along the transect. In addition, from several soils the molecular composition of SOM was further characterized with depth in the current soil as well as the entire first and the top of the second paleosol using GC/MS analyses of extractable lipids and Pyrolysis-GC/MS analyses of bulk organic matter. Our results show that organic carbon stocks in the mineral soil under forest a páramo vegetation were roughly twice as large as global averages for volcanic ash soils, regardless of whether the first 30cm, 100cm or 200cm were considered. We found the carbon stabilization mechanisms involved to be: i) direct stabilization of SOM in organo-metallic (Al-OM) complexes; ii) indirect protection of SOM through low soil pH and toxic levels of Al; and iii) physical protection of SOM due to a very high microporosity of the soil (Tonneijck et al., 2010; Jansen et al. 2011). When examining the organic carbon at a molecular level, interestingly we found extensive degradation of lignin in the topsoil while extractable lipids were preferentially preserved in the subsoil (Nierop and Jansen, 2009). Both vegetation

  2. Tropical forest soil microbial communities couple iron and carbon biogeochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Dubinsky, E.A.; Silver, W.L.; Firestone, M.K.

    2009-10-15

    We report that iron-reducing bacteria are primary mediators of anaerobic carbon oxidation in upland tropical soils spanning a rainfall gradient (3500 - 5000 mm yr-1) in northeast Puerto Rico. The abundant rainfall and high net primary productivity of these tropical forests provide optimal soil habitat for iron-reducing and iron-oxidizing bacteria. Spatially and temporally dynamic redox conditions make iron-transforming microbial communities central to the belowground carbon cycle in these wet tropical forests. The exceedingly high abundance of iron-reducing bacteria (up to 1.2 x 10{sup 9} cells per gram soil) indicated that they possess extensive metabolic capacity to catalyze the reduction of iron minerals. In soils from the higher rainfall sites, measured rates of ferric iron reduction could account for up to 44 % of organic carbon oxidation. Iron reducers appeared to compete with methanogens when labile carbon availability was limited. We found large numbers of bacteria that oxidize reduced iron at sites with high rates of iron reduction and large numbers of iron-reducers. the coexistence of large populations of ironreducing and iron-oxidizing bacteria is evidence for rapid iron cycling between its reduced and oxidized states, and suggests that mutualistic interactions among these bacteria ultimately fuel organic carbon oxidation and inhibit CH4 production in these upland tropical forests.

  3. Climate change affects carbon allocation to the soil in shrublands

    DEFF Research Database (Denmark)

    Gorissen, A.; Tietema, A.; Joosten, N.N.

    2004-01-01

    Climate change may affect ecosystem functioning through increased temperatures or changes in precipitation patterns. Temperature and water availability are important drivers for ecosystem processes such as photosynthesis, carbon translocation, and organic matter decomposition. These climate changes...... may affect the supply of carbon and energy to the soil microbial population and subsequently alter decomposition and mineralization, important ecosystem processes in carbon and nutrient cycling. In this study, carried out within the cross-European research project CLIMOOR, the effect of climate change...... in the growing season. Differences in climate, soil, and plant characteristics resulted in a gradient in the severity of the drought effects on net carbon uptake by plants with the impact being most severe in Spain, followed by Denmark, with the UK showing few negative effects at significance levels of p less...

  4. Assessing the soil microbial carbon budget: Probing with salt stress

    Science.gov (United States)

    Rath, Kristin; Rousk, Johannes

    2014-05-01

    The amount of carbon stored as soil organic matter (SOM) constitutes a pool more than double the size of the atmospheric carbon pool. Soil respiration represents one of the largest fluxes of carbon between terrestrial ecosystems and the atmosphere. A large fraction of the CO2 released by soils is produced by the microbial decomposition of SOM. The microbial carbon budget is characterized by their carbon use efficiency, i.e. the partitioning of substrate into growth and respiration. This will shape the role of the soil as a net source or sink for carbon. One of the canonical factors known to influence microbial processes in soil is pH. In aquatic systems salinity has been found to have a comparably strong influence as pH. However salinity remains understudied in soil, despite its growing relevance due to land use change and agricultural practices. The aim of this project is to understand how microbial carbon dynamics respond to disturbance by changing environmental conditions, using salinity as a reversible stressor. First, we compiled a comparative analysis of the sensitivity of different microbial processes to increasing salt concentrations. Second, we compared different salts to determine whether salt toxicity depended on the identity of the salt. Third, we used samples from a natural salinity gradient to assess if a legacy of salt exposure can influence the microbial response to changing salt concentrations. If salt had an ecologically significant effect in shaping these communities, we would assume that microbial processes would be less sensitive to an increase in salt concentrations. The sensitivity of microbial processes to salt was investigated by establishing inhibition curves in order to estimate EC50 values (the concentration resulting in 50% inhibition). These EC50 values were used to compare bacterial and fungal growth responses, as well as catabolic processes such as respiration and nitrogen mineralisation. Initial results suggest that growth related

  5. Soil organic carbon sequestration potential of conservation vs. conventional tillage

    Science.gov (United States)

    Meurer, Katharina H. E.; Ghafoor, Abdul; Haddaway, Neal R.; Bolinder, Martin A.; Kätterer, Thomas

    2017-04-01

    Soil tillage has been associated with many negative impacts on soil quality, especially a reduction in soil organic carbon (SOC). The benefits of no tillage (NT) on topsoil SOC concentrations have been demonstrated in several reviews, but the effect of reduced tillage (RT) compared to conventional tillage (CT) that usually involves soil inversion through moldboard ploughing is still unclear. Moreover, the effect of tillage on total SOC stocks including deeper layers is still a matter of considerable debate, because the assessment depends on many factors such as depth and method of measurement, cropping systems, soil type, climatic conditions, and length of the experiments used for the analysis. From a recently published systematic map database consisting of 735 long-term field experiments (≥ 10 years) within the boreal and temperate climate zones (Haddaway et al. 2015; Environmental Evidence 4:23), we selected all tillage studies (about 80) reporting SOC concentrations along with dry soil bulk density and conducted a systematic review. SOC stocks were calculated considering both fixed soil depths and by using the concept of equivalent soil mass. A meta-analysis was used to determine the influence of environmental, management, and soil-related factors regarding their prediction potential on SOC stock changes between the tillage categories NT, RT, and CT. C concentrations and stocks to a certain depth were generally highest under NT, intermediate under RT, and lowest under CT. However, this effect was mainly limited to the first 15 cm and disappeared or was even reversed in deeper layers, especially when adjusting soil depth according to the equivalent soil mineral mass. Our study highlights the impact of tillage-induced changes in soil bulk density between treatments and shows that neglecting the principles of equivalent soil mass leads to overestimation of SOC stocks for by conservation tillage practices.

  6. Carbon and nitrogen in Danish forest soils - Contents and distribution determined by soil order

    DEFF Research Database (Denmark)

    Vejre, Henrik; Callesen, Ingeborg; Vesterdal, Lars

    2003-01-01

    Increasing atmospheric CO2 concentrations, and widespread deposition of N to terrestrial ecosystems has increased the focus on soil C and N pools. The aim of this study was to estimate the size and distribution of organic C and N pools in well-drained Danish forest soils. We examined 140 forest......)) and least in Spodosols (0.51 kg m(-2)). The main contributor to the high C content in Spodosols is the spodic horizons containing illuvial humus, and thick organic horizons. Carbon and N concentrations decreased with soil depth. Soil clay content was negatively correlated to C content and positively...

  7. Effects of Soil Compaction and Organic Carbon Content on Preferential Flow in Loamy Field Soils

    DEFF Research Database (Denmark)

    Soares, Antonio; Moldrup, Per; Vendelboe, Anders Lindblad

    2015-01-01

    . Tritium breakthrough experiments were conducted at constant flow rates and obtained breakthrough curves were analyzed for 5% tracer arrival time and dispersivity. Both soils showed strong correlations between soil compaction, expressed in terms of bulk density, and preferential flow. Interestingly......, the relationships between bulk density and tritium transport parameters were markedly different for the two soils although the relationship between bulk density and macroporosity was nearly identical. The difference was likely caused by the higher organic carbon content of one soil leading to a more pronounced pipe...

  8. Soil carbon sequestration potential of permanent pasture and continuous cropping soils in New Zealand.

    Science.gov (United States)

    McNally, Sam R; Beare, Mike H; Curtin, Denis; Meenken, Esther D; Kelliher, Francis M; Calvelo Pereira, Roberto; Shen, Qinhua; Baldock, Jeff

    2017-11-01

    Understanding soil organic carbon (SOC) sequestration is important to develop strategies to increase the SOC stock and, thereby, offset some of the increases in atmospheric carbon dioxide. Although the capacity of soils to store SOC in a stable form is commonly attributed to the fine (clay + fine silt) fraction, the properties of the fine fraction that determine the SOC stabilization capacity are poorly known. The aim of this study was to develop an improved model to estimate the SOC stabilization capacity of Allophanic (Andisols) and non-Allophanic topsoils (0-15 cm) and, as a case study, to apply the model to predict the sequestration potential of pastoral soils across New Zealand. A quantile (90th) regression model, based on the specific surface area and extractable aluminium (pyrophosphate) content of soils, provided the best prediction of the upper limit of fine fraction carbon (FFC) (i.e. the stabilization capacity), but with different coefficients for Allophanic and non-Allophanic soils. The carbon (C) saturation deficit was estimated as the difference between the stabilization capacity of individual soils and their current C concentration. For long-term pastures, the mean saturation deficit of Allophanic soils (20.3 mg C g -1 ) was greater than that of non-Allophanic soils (16.3 mg C g -1 ). The saturation deficit of cropped soils was 1.14-1.89 times that of pasture soils. The sequestration potential of pasture soils ranged from 10 t C ha -1 (Ultic soils) to 42 t C ha -1 (Melanic soils). Although meeting the estimated national soil C sequestration potential (124 Mt C) is unrealistic, improved management practices targeted to those soils with the greatest sequestration potential could contribute significantly to off-setting New Zealand's greenhouse gas emissions. As the first national-scale estimate of SOC sequestration potential that encompasses both Allophanic and non-Allophanic soils, this serves as an informative case study for the international

  9. Soil carbon inventories and carbon-13 on a latitude transect in Siberia

    Czech Academy of Sciences Publication Activity Database

    Bird, M. I.; Šantrůčková, Hana; Arneth, A.; Grigoriev, S.; Gleixner, G.; Kalaschnikov, Y. N.; Lloyd, J.; Schulze, E. D.

    2002-01-01

    Roč. 5, 54B (2002), s. 631-641 ISSN 0280-6509 Institutional research plan: CEZ:AV0Z6066911 Keywords : soil carbon inventories * carbon-13 * Siberia Subject RIV: EH - Ecology, Behaviour Impact factor: 3.196, year: 2002

  10. Carbon and black carbon in Yosemite National Park soils: sources, prescribed fire impacts, and policies

    Science.gov (United States)

    Shrestha, G.; Traina, S. J.

    2012-12-01

    We investigated the chemical and radiocarbon properties of black carbon recently deposited and accumulated in surface soils of six sites along an altitudinal gradient in Yosemite National Park, central California. The effect of prescribed (or controlled) forest burning on existing carbon and black carbon in surface soils was assessed to illuminate the role of this forest management and wildfire control strategy in the soil carbon cycle. The proportional contribution of fossil fuel or radiocarbon dead carbon versus biomass sources on these black carbon materials was analyzed to elucidate their origin, estimate their ages and explore the possible effects of prescribed burning on the amount of black carbon produced recently as well as historically. Supplementing these field results, we conducted a comparative spatial analysis of recent prescribed burn and wildfire coverage in Central California's San Joaquin Valley to approximate the effectiveness of prescribed burning for wildfire prevention. Federal and California policies pertaining to prescribed forest fires and/or black carbon were then evaluated for their effectiveness, air quality considerations, and environmental benefits. 13C NMR spectrum of soil surface char from study sites Prescribed burn coverage versus wildfires in central California

  11. Effects of strip and full-width tillage on soil carbon IV oxide-carbon ...

    African Journals Online (AJOL)

    ... determine the effects of strip tillage and full-width tillage treatments on soil carbon IV oxide-carbon (CO2-C) fluxes, bacterial and fungal populations in growing period of sunflower (Helianthus annus). A row-crop rotary hoe with C type blades was used to create three strip widths by changing the connection of blades of the ...

  12. Global soil carbon projections are improved by modelling microbial processes

    Science.gov (United States)

    Wieder, William R.; Bonan, Gordon B.; Allison, Steven D.

    2013-10-01

    Society relies on Earth system models (ESMs) to project future climate and carbon (C) cycle feedbacks. However, the soil C response to climate change is highly uncertain in these models and they omit key biogeochemical mechanisms. Specifically, the traditional approach in ESMs lacks direct microbial control over soil C dynamics. Thus, we tested a new model that explicitly represents microbial mechanisms of soil C cycling on the global scale. Compared with traditional models, the microbial model simulates soil C pools that more closely match contemporary observations. It also projects a much wider range of soil C responses to climate change over the twenty-first century. Global soils accumulate C if microbial growth efficiency declines with warming in the microbial model. If growth efficiency adapts to warming, the microbial model projects large soil C losses. By comparison, traditional models project modest soil C losses with global warming. Microbes also change the soil response to increased C inputs, as might occur with CO2 or nutrient fertilization. In the microbial model, microbes consume these additional inputs; whereas in traditional models, additional inputs lead to C storage. Our results indicate that ESMs should simulate microbial physiology to more accurately project climate change feedbacks.

  13. Minor Stimulation of Soil Carbon Storage by Nitrogen Addition

    Science.gov (United States)

    Luo, Y.; Lu, M.; Zhou, X.; Li, B.; Fang, C.; Chen, J.

    2009-04-01

    Anthropogenic nitrogen (N) fertilization and deposition adds 292 Tg N each year, largely to terrestrial ecosystems. N addition usually stimulates biomass growth and results in increases in plant carbon (C) pool sizes. Whether this stimulated biomass growth would lead to increased C storage in soils - the largest pool in the land - is a critical issue for the mitigation of climate change. Fossil fuel burning and deforestation emit about 10 Gt C per year to the atmosphere. Global analysis has shown that terrestrial ecosystems absorb a substantial portion of emitted C. If N addition is one key mechanism underlying contemporary terrestrial C sequestration, the land C sink would be likely to be enhanced as N deposition and fertilization are anticipated to increase in the future. However, impacts of C addition on soil C sequestration remain highly controversial. To reveal a central tendency, we synthesized results from nearly 300 studies. Our analysis showed that N addition did not significantly stimulate soil C storage in nonagricultural ecosystems (e.g., forests and grasslands) but significantly in agricultural ecosystems. Averaged effects of N addition on soil C storage were minor across all ecosystems. N-induced changes in soil C stocks were significantly regulated by soil C:N. Nitrogen addition tends to stimulate C storage in low C:N soil but increase C loss in high C:N soil. Our results indicate that N stimulation of C storage primarily occurs in plant pools but is highly limited in soil pools.

  14. Centennial black carbon turnover observed in a Russian steppe soil

    Directory of Open Access Journals (Sweden)

    K. Hammes

    2008-09-01

    Full Text Available Black carbon (BC, from incomplete combustion of fuels and biomass, has been considered highly recalcitrant and a substantial sink for carbon dioxide. Recent studies have shown that BC can be degraded in soils. We use two soils with very low spatial variability sampled 100 years apart in a Russian steppe preserve to generate the first whole-profile estimate of BC stocks and turnover in the field. Quantities of fire residues in soil changed significantly over a century. Black carbon stock was 2.5 kg m−2, or about 7–10% of total organic C in 1900. With cessation of biomass burning, BC stocks decreased 25% over a century, which translates into a centennial soil BC turnover (293 years best estimate; range 182–541 years, much faster than so-called inert or passive carbon in ecosystem models. The turnover time presented here is for loss by all processes, namely decomposition, leaching, and erosion, although the latter two were probably insignificant in this case. Notably, at both time points, the peak BC stock was below 30 cm, a depth interval, which is not typically accounted for. Also, the quality of the fire residues changed with time, as indicated by the use benzene polycarboxylic acids (BPCA as molecular markers. The proportions of less-condensed (and thus more easily degradable BC structures decreased, whereas the highly condensed (and more recalcitrant BC structures survived unchanged over the 100-year period. Our results show that BC cannot be assumed chemically recalcitrant in all soils, and other explanations for very old soil carbon are needed.

  15. Centennial black carbon turnover observed in a Russia steppe soil

    Energy Technology Data Exchange (ETDEWEB)

    Hammes, K.; Torn, M.S.; Lapenas, A.G.; Schmidt, M.W.I.

    2008-09-15

    Black carbon (BC), from incomplete combustion of fuels and biomass, has been considered highly recalcitrant and a substantial sink for carbon dioxide. Recent studies have shown that BC can be degraded in soils. We use two soils with very low spatial variability sampled 100 years apart in a Russian steppe preserve to generate the first whole-profile estimate of BC stocks and turnover in the field. Quantities of fire residues in soil changed significantly over a century. Black carbon stock was 2.5 kg m{sup -2}, or about 7-10% of total organic C in 1900. With cessation of biomass burning, BC stocks decreased 25% over a century, which translates into a centennial soil BC turnover (293 years best estimate; range 182-541 years), much faster than so-called inert or passive carbon in ecosystem models. The turnover time presented here is for loss by all processes, namely decomposition, leaching, and erosion, although the latter two were probably insignificant in this case. Notably, at both time points, the peak BC stock was below 30 cm, a depth interval, which is not typically accounted for. Also, the quality of the fire residues changed with time, as indicated by the use benzene poly carboxylic acids (BPCA) as molecular markers. The proportions of less-condensed (and thus more easily degradable) BC structures decreased, whereas the highly condensed (and more recalcitrant) BC structures survived unchanged over the 100-year period. Our results show that BC cannot be assumed chemically recalcitrant in all soils, and other explanations for very old soil carbon are needed.

  16. Global Impact of Land Use on Soil Carbon Storage

    Science.gov (United States)

    Sanderman, J.; Hengl, T.; Fiske, G. J.; Cheney, E.

    2016-12-01

    Land use and land cover change has resulted in substantial losses of carbon from soils globally. This historic loss in soil organic carbon now represents a significant climate mitigation opportunity. Current estimates of the potential soil organic carbon (SOC) sink strength generally come from simplistic bookkeeping calculations that have been disaggregated to at best the continental scale. Others have taken a modeling approach whereby agroecosystem models have been run using alternative management practices to estimate SOC sequestration potential. A third approach which is adopted here is to use a data-driven spatial modeling approach whereby measured SOC stocks from minimally distrubed regions are projected across the highly managed regions of the world. The International Soil Reference and Information Center (www.isric.org) curates the largest repository of spatially explicit soil data which now includes data from over 150,000 soil profiles globally. From this dataset, we have masked out data from profiles collected from used parts of the globe. Then SOC stocks were related to factors which are known to control SOC storage using machine learning algorithms. Spatially continuous data layers included climate, topography, lithology and potential vegetation class. The trained machine learning algorithms were then used to project potential SOC stocks across the entire global land surface at a resolution of 1 km. In addition to an assessment of model performance in the development stage, an independent test set of over 400 paired-plot (native v. agricultural) measurements of SOC stocks within major agricultural regions was collected to help validate model output. Land area with the largest carbon debit and thus the greatest potential of SOC storage was revealed by comparison of this potential SOC map with a map of actual SOC values (SoilGrids250m) that was produced using a consistent spatial modeling approach.

  17. Long-term rotation studies and the effect on soil organic carbon in cotton soils.

    Science.gov (United States)

    Braunack, M.; Hulugalle, N.; Rochester, I.

    2012-04-01

    Three long-term experiments conducted at the Australian Cotton Research Institute (ACRI) on vertosols examined the effect of tillage and stubble management over 26 years (E1), crop rotations over 9 years (E2) and the use of legumes over 16 years (E3) in maintaining soil quality and nitrogen contribution for subsequent cotton crops. Two of the experiments (E 1, 2) were on soils with a subsoil constraint of sodicity (ESP>10 %), while the third (E3) was on soil with less subsoil sodicity (ESP=5%). E1 compared continuous cotton with conventional tillage (CC_MXT), continuous cotton with minimum tillage (CC_MNT) and a cotton-wheat rotation with minimum tillage where wheat stubble was incorporated until 1999 and retained as standing stubble thereafter (CW_MNT). Cotton stubble was incorporated in all treatments. E2 compared cotton-vetch-cotton (CVC), cotton-fallow-cotton (CFC), cotton-wheat-fallow-cotton (CWFC), fallow-cotton-wheat-fallow-cotton (FCWFC), cotton-wheat-fallow-vetch-cotton-wheat (CWFVCW) and fallow-cotton-wheat-fallow-vetch-cotton-wheat (FCWFVCW). Vetch was retained as surface mulch, wheat stubble incorporated in both CWFC and FCWFC but retained as standing stubble in CWFVCW and FCWFVCW. E3 compared cotton-vetch-cotton-vetch (CVCV), cotton-fallow-cotton-fallow (CFCFC), cotton-wheat-fallow-cotton (CWFC), cotton-wheat-vetch-cotton (CWVC) and cotton-faba bean-fallow-cotton (CFbFC). Soils were sampled to 1.2 m in E1 and E2 and to 0.9 m in E3 and analysed for total soil organic carbon. Stubble was conserved in all experiments, but was incorporated in E3 and retained as standing stubble in E1 and E2 except as noted. Results indicate that in E1, soil organic carbon decreased over time under continuous cotton for all tillage treatments, however including wheat in the rotation slowed the decline and tended to increase soil organic carbon in the immediate surface layer. In E2 soil organic carbon decreased with depth and remained relatively constant, while soil organic

  18. How conservation agriculture can mitigate greenhouse gas emissions and enhance soil carbon storage in croplands

    Science.gov (United States)

    Conservation agriculture can mitigate greenhouse gas (GHG) emissions from agriculture by enhancing soil carbon sequestration, improving soil quality, N-use efficiency and water use efficiencies, and reducing fuel consumption. Management practices that increase carbon inputs and while reducing carbo...

  19. A Compilation of Global Soil Microbial Biomass Carbon, Nitrogen, and Phosphorus Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides the concentrations of soil microbial biomass carbon (C), nitrogen (N) and phosphorus (P), soil organic carbon, total nitrogen, and total...

  20. 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

  1. 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

  2. Soil organic carbon sequestration and tillage systems in Mediterranean environments

    Science.gov (United States)

    Francaviglia, Rosa; Di Bene, Claudia; Marchetti, Alessandro; Farina, Roberta

    2016-04-01

    Soil carbon sequestration is of special interest in Mediterranean areas, where rainfed cropping systems are prevalent, inputs of organic matter to soils are low and mostly rely on crop residues, while losses are high due to climatic and anthropic factors such as intensive and non-conservative farming practices. The adoption of reduced or no tillage systems, characterized by a lower soil disturbance in comparison with conventional tillage, has proved to be positively effective on soil organic carbon (SOC) conservation and other physical and chemical processes, parameters or functions, e.g. erosion, compaction, ion retention and exchange, buffering capacity, water retention and aggregate stability. Moreover, soil biological and biochemical processes are usually improved by the reduction of tillage intensity. The work deals with some results available in the scientific literature, and related to field experiment on arable crops performed in Italy, Greece, Morocco and Spain. Data were organized in a dataset containing the main environmental parameters (altitude, temperature, rainfall), soil tillage system information (conventional, minimum and no-tillage), soil parameters (bulk density, pH, particle size distribution and texture), crop type, rotation, management and length of the experiment in years, initial SOCi and final SOCf stocks. Sampling sites are located between 33° 00' and 43° 32' latitude N, 2-860 m a.s.l., with mean annual temperature and rainfall in the range 10.9-19.6° C and 355-900 mm. SOC data, expressed in t C ha-1, have been evaluated both in terms of Carbon Sequestration Rate, given by [(SOCf-SOCi)/length in years], and as percentage change in comparison with the initial value [(SOCf-SOCi)/SOCi*100]. Data variability due to the different environmental, soil and crop management conditions that influence SOC sequestration and losses will be examined.

  3. Community structure and soil pH determine chemoautotrophic carbon dioxide fixation in drained paddy soils.

    Science.gov (United States)

    Long, Xi-En; Yao, Huaiying; Wang, Juan; Huang, Ying; Singh, Brajesh K; Zhu, Yong-Guan

    2015-06-16

    Previous studies suggested that microbial photosynthesis plays a potential role in paddy fields, but little is known about chemoautotrophic carbon fixers in drained paddy soils. We conducted a microcosm study using soil samples from five paddy fields to determine the environmental factors and quantify key functional microbial taxa involved in chemoautotrophic carbon fixation. We used stable isotope probing in combination with phospholipid fatty acid (PLFA) and molecular approaches. The amount of microbial (13)CO2 fixation was determined by quantification of (13)C-enriched fatty acid methyl esters and ranged from 21.28 to 72.48 ng of (13)C (g of dry soil)(-1), and the corresponding ratio (labeled PLFA-C:total PLFA-C) ranged from 0.06 to 0.49%. The amount of incorporationof (13)CO2 into PLFAs significantly increased with soil pH except at pH 7.8. PLFA and high-throughput sequencing results indicated a dominant role of Gram-negative bacteria or proteobacteria in (13)CO2 fixation. Correlation analysis indicated a significant association between microbial community structure and carbon fixation. We provide direct evidence of chemoautotrophic C fixation in soils with statistical evidence of microbial community structure regulation of inorganic carbon fixation in the paddy soil ecosystem.

  4. Factors for Microbial Carbon Sources in Organic and Mineral Soils from Eastern United States Deciduous Forests

    Energy Technology Data Exchange (ETDEWEB)

    Stitt, Caroline R. [Mills College, Oakland, CA (United States)

    2013-09-16

    Forest soils represent a large portion of global terrestrial carbon; however, which soil carbon sources are used by soil microbes and respired as carbon dioxide (CO2) is not well known. This study will focus on characterizing microbial carbon sources from organic and mineral soils from four eastern United States deciduous forests using a unique radiocarbon (14C) tracer. Results from the dark incubation of organic and mineral soils are heavily influenced by site characteristics when incubated at optimal microbial activity temperature. Sites with considerable differences in temperature, texture, and location differ in carbon source attribution, indicating that site characteristics play a role in soil respiration.

  5. Hyperspectral Analysis of Soil Nitrogen, Carbon, Carbonate, and Organic Matter Using Regression Trees

    Directory of Open Access Journals (Sweden)

    L. Monika Moskal

    2012-08-01

    Full Text Available The characterization of soil attributes using hyperspectral sensors has revealed patterns in soil spectra that are known to respond to mineral composition, organic matter, soil moisture and particle size distribution. Soil samples from different soil horizons of replicated soil series from sites located within Washington and Oregon were analyzed with the FieldSpec Spectroradiometer to measure their spectral signatures across the electromagnetic range of 400 to 1,000 nm. Similarity rankings of individual soil samples reveal differences between replicate series as well as samples within the same replicate series. Using classification and regression tree statistical methods, regression trees were fitted to each spectral response using concentrations of nitrogen, carbon, carbonate and organic matter as the response variables. Statistics resulting from fitted trees were: nitrogen R2 0.91 (p < 0.01 at 403, 470, 687, and 846 nm spectral band widths, carbonate R2 0.95 (p < 0.01 at 531 and 898 nm band widths, total carbon R2 0.93 (p < 0.01 at 400, 409, 441 and 907 nm band widths, and organic matter R2 0.98 (p < 0.01 at 300, 400, 441, 832 and 907 nm band widths. Use of the 400 to 1,000 nm electromagnetic range utilizing regression trees provided a powerful, rapid and inexpensive method for assessing nitrogen, carbon, carbonate and organic matter for upper soil horizons in a nondestructive method.

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

    Science.gov (United States)

    Chen, Yaping; Chen, Guangcheng; Ye, Yong

    2015-09-01

    Soil properties and soil-atmosphere fluxes of CO2, CH4 and N2O 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 CO2-equivalent flux of 137.27 mg CO2 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 CH4 and N2O 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. Copyright © 2015. Published

  7. SOIL ORGANIC CARBON LEVELS IN SOILS OF CONTRASTING LAND USES IN SOUTHEASTERN NIGERIA

    Directory of Open Access Journals (Sweden)

    Chinyere Blessing Okebalama

    2017-12-01

    Full Text Available Land use change affects soil organic carbon (SOC storage in tropical soils, but information on the influence of land use change on segmental topsoil organic carbon stock is lacking. The study investigated SOC levels in Awgu (L, Okigwe (CL, Nsukka I (SL, and Nsukka II (SCL locations in southeastern Nigeria. Land uses considered in each location were the cultivated (manually-tilled and the adjacent uncultivated (4-5 year bush-fallow soils from which samples at 0-10, 10-20, and 20-30 cm topsoil depth were assessed. The SOC level decreased with topsoil depth in both land uses. Overall, the SOC level at 0-30 cm was between 285.44 and 805.05 Mg ha-1 amongst the soils.  The uncultivated sites stored more SOC than its adjacent cultivated counterpart at 0-10 and 10-20 cm depth, except in Nsukka II soils, which had significantly higher SOC levels in the cultivated than the uncultivated site. Nonetheless, at 20-30 cm depth, the SOC pool across the fallowed soils was statistically similar when parts of the same soil utilization type were tilled and cultivated. Therefore, while 4 to 5 years fallow may be a useful strategy for SOC stabilization within 20-30 cm topsoil depth in the geographical domain, segmental computation of topsoil organic carbon pool is critical.

  8. Soil Functional Mapping: A Geospatial Framework for Scaling Soil Carbon Cycling

    Science.gov (United States)

    Lawrence, C. R.

    2017-12-01

    Climate change is dramatically altering biogeochemical cycles in most terrestrial ecosystems, particularly the cycles of water and carbon (C). These changes will affect myriad ecosystem processes of importance, including plant productivity, C exports to aquatic systems, and terrestrial C storage. Soil C storage represents a critical feedback to climate change as soils store more C than the atmosphere and aboveground plant biomass combined. While we know plant and soil C cycling are strongly coupled with soil moisture, substantial unknowns remain regarding how these relationships can be scaled up from soil profiles to ecosystems. This greatly limits our ability to build a process-based understanding of the controls on and consequences of climate change at regional scales. In an effort to address this limitation we: (1) describe an approach to classifying soils that is based on underlying differences in soil functional characteristics and (2) examine the utility of this approach as a scaling tool that honors the underlying soil processes. First, geospatial datasets are analyzed in the context of our current understanding of soil C and water cycling in order to predict soil functional units that can be mapped at the scale of ecosystems or watersheds. Next, the integrity of each soil functional unit is evaluated using available soil C data and mapping units are refined as needed. Finally, targeted sampling is conducted to further differentiate functional units or fill in any data gaps that are identified. Completion of this workflow provides new geospatial datasets that are based on specific soil functions, in this case the coupling of soil C and water cycling, and are well suited for integration with regional-scale soil models. Preliminary results from this effort highlight the advantages of a scaling approach that balances theory, measurement, and modeling.

  9. Payback time for soil carbon and sugar-cane ethanol

    Science.gov (United States)

    Mello, Francisco F. C.; Cerri, Carlos E. P.; Davies, Christian A.; Holbrook, N. Michele; Paustian, Keith; Maia, Stoécio M. F.; Galdos, Marcelo V.; Bernoux, Martial; Cerri, Carlos C.

    2014-07-01

    The effects of land-use change (LUC) on soil carbon (C) balance has to be taken into account in calculating the CO2 savings attributed to bioenergy crops. There have been few direct field measurements that quantify the effects of LUC on soil C for the most common land-use transitions into sugar cane in Brazil, the world's largest producer . We quantified the C balance for LUC as a net loss (carbon debt) or net gain (carbon credit) in soil C for sugar-cane expansion in Brazil. We sampled 135 field sites to 1 m depth, representing three major LUC scenarios. Our results demonstrate that soil C stocks decrease following LUC from native vegetation and pastures, and increase where cropland is converted to sugar cane. The payback time for the soil C debt was eight years for native vegetation and two to three years for pastures. With an increasing need for biofuels and the potential for Brazil to help meet global demand, our results will be invaluable for guiding expansion policies of sugar-cane production towards greater sustainability.

  10. SWV determination of glyphosate in Burkina Faso soils using carbon ...

    African Journals Online (AJOL)

    This paper presents an evaluation using carbon fiber microelectrode (CFME) for the determination of glyphosate in soils from Burkina Faso treated with Glyphonet SL 360 by square wave voltammetry (SWV). The maximum intensity of the electrochemical response signal of glyphosate has been optimized and conditions ...

  11. Effects of Elevated Soil Carbon dioxide (CO2) Concentrations on ...

    African Journals Online (AJOL)

    PROF HORSFALL

    Author of correspondence: 1Department of Environmental Management and Toxicology, Faculty of Life Sciences, University of Benin,. Benin City, Ugbowo Campus ... Detection (ASGARD) facility which controls CO2 injection into the soil. Eight plots (each 2.5 x ... potential for leakage of stored carbon dioxide to the ocean or ...

  12. Pyrene mineralization in clay soil with and without organic Carbon ...

    African Journals Online (AJOL)

    Pyrene mineralization in clay soil with and without organic Carbon: the rol of adsorption and desorption kinetics equilibria. C N Owabor, J O Osarkunmwense. Abstract. No Abstract. Global Journal of Pure and Applied Physics Vol. 14 (1) 2008 pp. 109-114. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL ...

  13. Evaluation of the soil organic carbon, nitrogen and available ...

    African Journals Online (AJOL)

    The result obtained indicates that the level of these chemical properties were generally low as compared to standard measures and parameter for ratings soil fertility in the Nigerian Savanna. Keywords: Status of organic carbon, total nitrogen, available phosphorus, top horizons, research farm. Bowen Journal of Agriculture ...

  14. Atypical soil carbon distribution across a tropical steepland forest catena

    Science.gov (United States)

    Kristofer D. Johnson; F.N. Scatena; Whendee L. Silver

    2011-01-01

    Soil organic carbon (SOC) in a humid subtropical forest in Puerto Rico is higher at ridge locations compared to valleys, and therefore opposite to what is commonly observed in other forested hillslope catenas. To better understand the spatial distribution of SOC in this system, plots previously characterized by topographic position, vegetation type and stand age were...

  15. Review of Soil Carbon Management: Economics, Environmental and Societal Benefits

    Science.gov (United States)

    The book provides a “big picture” look at the processes and benefits of soil carbon (c) management. The book is targeted to policy makers and gives policy recommendations in addition to providing technical information. The first section of the book contains a summary of current programs that foste...

  16. Development of a Soil Organic Carbon Baseline for Otjozondjupa, Namibia

    NARCIS (Netherlands)

    Nijbroek, R.; Kempen, B.; Mutua, J.; Soderstrom, M.; Piikki, K.; Hengari, S.; Andreas, A.

    2017-01-01

    Land Degradation Neutrality (LDN) has been piloted in 14 countries and will be scaled up to over 120 countries. As a LDN pilot country, Namibia developed sub-national LDN baselines in Otjozondjupa Region. In addition to the three LDN indicators (soil organic carbon, land productivity and land cover

  17. Experimental evidence that mycorrhizal nitrogen strategies affect soil carbon

    Science.gov (United States)

    Nina Wurzburger; E. N. Jack Brookshire

    2017-01-01

    Most land plants acquire nitrogen (N) through associations with arbuscular (AM) and ectomycorrhizal (ECM) fungi, but these symbionts employ contrasting strategies for N acquisition, which may lead to different stocks of soil carbon (C). We experimentally test this hypothesis with a mesocosm system where AM and ECM tree seedling roots, or their hyphae only, could access...

  18. Empirical evidence of soil carbon changes in bioenergy cropping systems

    Science.gov (United States)

    Biofuels are seen as a near-term solution to reduce greenhouse gas (GHG) emissions, reduce petroleum usage, and diversify rural economies. Accurate accounting of all GHG emissions is necessary to measure the overall carbon (C) intensity of new biofuel feedstocks. Changes in direct soil organic carb...

  19. Ethanol production from crop residues and soil organic carbon

    NARCIS (Netherlands)

    Reijnders, L.

    2008-01-01

    In decision making about the use of residues from annual crops for ethanol production, alternative applications of these residues should be considered. Especially important is the use of such residues for stabilizing and increasing levels of soil organic carbon. Such alternative use leads to a

  20. Soil organic carbon and nitrogen stocks along a seasonal wetland ...

    African Journals Online (AJOL)

    Ecosystems of central and southern Africa are occupied by some of the largest seasonal wetlands commonly called dambos. Dambos are likely to store huge stocks of soil organic carbon (SOC) because of their saturated conditions. However, most available literature report average SOC concentrations while ignoring ...

  1. Mapping soil organic carbon content by geographically weighted regression

    NARCIS (Netherlands)

    Song, Xiao Dong; Brus, Dick J.; Liu, Feng; Li, De Cheng; Zhao, Yu Guo; Yang, Jin Ling; Zhang, Gan Lin

    2016-01-01

    In large heterogeneous areas the relationship between soil organic carbon (SOC) and environmental covariates may vary throughout the area, bringing about difficulty for accurate modeling of the regional SOC variation. The benefit of local, geographically weighted regression (GWR) coefficients was

  2. Soil Carbon Sequestration and the Greenhouse Effect (2nd Edition)

    Science.gov (United States)

    This volume is a second edition of the book “Soil Carbon Sequestration and The Greenhouse Effect”. The first edition was published in 2001 as SSSA Special Publ. #57. The present edition is an update of the concepts, processes, properties, practices and the supporting data. All chapters are new co...

  3. Topographic variability influences the carbon sequestration potential of arable soils

    DEFF Research Database (Denmark)

    Chirinda, Ngoni; Elsgaard, Lars; Thomsen, Ingrid Kaag

    2012-01-01

    There is presently limited knowledge on the influence of field spatial variability on the carbon (C) sink-source relationships in arable landscapes. This is accompanied by the fact that our understanding of soil profile C dynamics is also limited. This study aimed at investigating how spatial...

  4. Black carbon and organic matter stabilization in soil

    Science.gov (United States)

    Lehmann, J.; Liang, B.; Sohi, S.; Gaunt, J.

    2007-12-01

    Interaction with minerals is key to stabilization of organic matter in soils. Stabilization is commonly perceived to occur due to entrapment in pore spaces, encapsulation within aggregates or interaction with mineral surfaces. Typically only interactions between organic matter and minerals are considered in such a model. Here we demonstrate that black carbon may act very similar to minerals in soil in that it enhances the stabilization of organic matter. Mineralization of added organic matter was slower and incorporation into intra-aggregate fractions more rapid in the presence of black carbon. Added double-labeled organic matter was recovered in fractions with high amounts of black carbon. Synchrotron-based near-edge x-ray fine structure (NEXAFS) spectroscopy coupled to scanning transmission x-ray microscopy (STXM) suggested a possible interaction of microorganisms with black carbon surfaces and metabolization of residues. These findings suggest a conceptual model that includes carbon-carbon interactions and by-passing for more rapid stabilization of litter into what is commonly interpreted as stable carbon pools.

  5. Paleoclimate studies in Brazil using carbon isotopes in soils

    Science.gov (United States)

    Pessenda, Luiz C. R.; Valencia, E. P. E.; Aravena, R.; Telles, E. C. C.; Boulet, R.

    This chapter presents carbon isotope data of soil organic matter (SOM), collected in natural forest ecosystems in different sites from Brazil. The studied areas are located in Londrina (Southern part of the country), Piracicaba (Southeast), Salitre (Central) and Altamira (Northern). This study is part of the research program on tropical and sub-tropical soils in Brazil, of which the main objective is to use carbon isotopes to provide information on vegetation changes and their relationships with climatic changes during the Holocene. 14C data of charcoal samples, the humin fraction and soil organic matter (SOM) contents, indicate that the organic matter of this area is at least of Holocene age. 13C data in SOM indicate that C4 plants were the dominant vegetation in Londrina and Piracicaba during the early and middle Holocene, while C3 plants were the dominant vegetation in Altamira and probably a mixture of C3 and C4 plants occurred in Salitre during the Holocene.

  6. Soil Organic Carbon Responses to Forest Expansion on Mountain Grasslands

    DEFF Research Database (Denmark)

    Guidi, Claudia

    involved into long-term stability are largely unknown. The aim of this PhD thesis was to explore changes in: (i) SOC stocks; (ii) physical SOC fractions; and (iii) labile soil carbon components following forest expansion on mountain grasslands. A land-use gradient located in the Southern Alps (Italy......Grassland abandonment followed by progressive forest expansion is the dominant land-use change in the European Alps. Contrasting trends in soil organic carbon (SOC) stocks have been reported for mountainous regions following forest expansion on grasslands. Moreover, its effects on SOC properties......) was examined, comprising managed grassland, two transitional phases in which grassland abandonment led to colonization by Picea abies (L.) Karst., and old forest dominated by Fagus sylvatica L. and P. abies. Mineral soil samples were physically separated through aggregate size and size-density fractionation...

  7. Short Communication: Soil carbon pools in different pasture systems

    Energy Technology Data Exchange (ETDEWEB)

    Cardozo, F.M. Jr.; Carneiro, R.F.V.; Leite, L.F.C.; Araujo, A.S.F.

    2016-11-01

    The aim of this study was to assess the carbon pools of a tropical soil where the native forest was replaced with different pasture systems. We studied five pasture production systems, including four monoculture systems with forage grasses such as Andropogon, Brachiaria, Panicum, and Cynodon, and an agroforestry system as well as a native vegetation plot. Greater availability of fulvic acid was detected in the agroforestry system as compared with that in the other systems. Higher lability of C was detected in the Andropogon system during the dry and rainy seasons and during the dry season in Cynodon. During the dry season, all pastures systems showed deficits in the net removal of atmospheric CO2. The structure and practices of the agroforestry system enables more carbon to be sequestered in the soil as compared with the monoculture pasture, suggesting that it is an important practice to mitigate climatic change and to improve soil quality. (Author)

  8. BOREAS TGB-12 Soil Carbon and Flux Data of NSA-MSA in Raster Format

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains (1) estimates of soil carbon stocks by horizon based on soil survey data and analyses of data from individual soil profiles; (2) estimates of...

  9. BOREAS TGB-12 Soil Carbon and Flux Data of NSA-MSA in Raster Format

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set contains (1) estimates of soil carbon stocks by horizon based on soil survey data and analyses of data from individual soil profiles; (2)...

  10. Impact of tree species on soil carbon stocks and soil acidity in southern Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Oostra, Swantje [Swedish Univ. of Agricultural Sciences, Alnarp (Sweden). Dept. of Landscape Planning; Majdi, Hooshang [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Ecology and Environmental Sciences; Olsson, Mats [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Forest Soils

    2006-10-15

    The impact of tree species on soil carbon stocks and acidity in southern Sweden was studied in a non-replicated plantation with monocultures of 67-year-old ash (Fraxinus excelsior L.), beech (Fagus silvatica L.), elm (Ulmus glabra Huds.), hornbeam (Carpinusbetulus L.), Norway spruce (Picea abies L.) and oak (Quercus robur L.). The site was characterized by a cambisol on glacial till. Volume-determined soil samples were taken from the O-horizon and mineral soil layers to 20 cm. Soil organic carbon (SOC), total nitrogen (TN), pH (H2O), cation-exchange capacity and base saturation at pH 7 and exchangeable calcium, magnesium, potassium and sodium ions were analysed in the soil fraction < 2 mm. Root biomass <5 mm in diameter) and its proportion in the forest floor and mineral soil varied between tree species. There was a vertical gradient under all species, with the highest concentrations of SOC, TN and base cations in the O-horizon and the lowest in the 10-20 cm layer. The tree species differed with respect to SOC, TN and soil acidity in the O-horizon and mineral soil. For SOC and TN, the range in the O-horizon was spruce> hornbeam > oak > beech > ash > elm. The pH in the O-horizon ranged in the order elm > ash > hornbeam > beech > oak > spruce. In the mineral soil, SOC and TN ranged in the order elm > oak > ash = hornbeam > spruce > beech, i.e. partly reversed, and pH ranged in the same order as for the O-horizon. It is suggested that spruce is the best option for fertile sites in southern Sweden if the aim is a high carbon sequestration rate, whereas elm, ash and hornbeam are the best solutions if the aim is a low soil acidification rate.

  11. Benchmark values for forest soil carbon stocks in Europe

    DEFF Research Database (Denmark)

    De Vos, Bruno; Cools, Nathalie; Ilvesniemi, Hannu

    2015-01-01

    confirmed global patterns reported for forest soils: ~ 50% of SOC was stored in the upper 20 cm, and ~ 55–65% in the upper 30 cm of soil. Assuming 163 Mha of European forest cover and by using various scaling up procedures, we estimated total stocks at 3.50–3.94 Gt C in forest floors and 21.4–22.7 Gt C......Soil organic carbon (SOC) stocks in forest floors and in mineral and peat forest soils were estimated at the European scale. The assessment was based on measured C concentration, bulk density, coarse fragments and effective soil depth data originating from 4914 plots in 22 EU countries belonging...... to the UN/ECE ICP Forests 16 × 16 km Level I network. Plots were sampled and analysed according to harmonized methods during the 2nd European Forest Soil Condition Survey. Using continuous carbon density depth functions, we estimated SOC stocks to 30-cm and 1-m depth, and stratified these stocks according...

  12. Soil Carbon and Nitrogen Stocks of Different Hawaiian Sugarcane Cultivars

    Directory of Open Access Journals (Sweden)

    Rebecca Tirado-Corbalá

    2015-06-01

    Full Text Available Sugarcane has been widely used as a biofuel crop due to its high biological productivity, ease of conversion to ethanol, and its relatively high potential for greenhouse gas reduction and lower environmental impacts relative to other derived biofuels from traditional agronomic crops. In this investigation, we studied four sugarcane cultivars (H-65-7052, H-78-3567, H-86-3792 and H-87-4319 grown on a Hawaiian commercial sugarcane plantation to determine their ability to store and accumulate soil carbon (C and nitrogen (N across a 24-month growth cycle on contrasting soil types. The main study objective establish baseline parameters for biofuel production life cycle analyses; sub-objectives included (1 determining which of four main sugarcane cultivars sequestered the most soil C and (2 assessing how soil C sequestration varies among two common Hawaiian soil series (Pulehu-sandy clay loam and Molokai-clay. Soil samples were collected at 20 cm increments to depths of up to 120 cm using hand augers at the three main growth stages (tillering, grand growth, and maturity from two experimental plots at to observe total carbon (TC, total nitrogen (TN, dissolved organic carbon (DOC and nitrates (NO−3 using laboratory flash combustion for TC and TN and solution filtering and analysis for DOC and NO−3. Aboveground plant biomass was collected and subsampled to determine lignin and C and N content. This study determined that there was an increase of TC with the advancement of growing stages in the studied four sugarcane cultivars at both soil types (increase in TC of 15–35 kg·m2. Nitrogen accumulation was more variable, and NO−3 (<5 ppm were insignificant. The C and N accumulation varies in the whole profile based on the ability of the sugarcane cultivar’s roots to explore and grow in the different soil types. For the purpose of storing C in the soil, cultivar H-65-7052 (TC accumulation of ~30 kg·m−2 and H-86-3792 (25 kg·m−2 rather H-78

  13. Aggregate and soil organic carbon dynamics in South Chilean Andisols

    Science.gov (United States)

    Huygens, D.; Boeckx, P.; Van Cleemput, O.; Oyarzún, C.; Godoy, R.

    2005-06-01

    Extreme sensitivity of soil organic carbon (SOC) to climate and land use change warrants further research in different terrestrial ecosystems. The aim of this study was to investigate the link between aggregate and SOC dynamics in a chronosequence of three different land uses of a south Chilean Andisol: a second growth Nothofagus obliqua forest (SGFOR), a grassland (GRASS) and a Pinus radiata plantation (PINUS). Total carbon content of the 0-10cm soil layer was higher for GRASS (6.7 kg C m-2) than for PINUS (4.3 kg C m-2, while TC content of SGFOR (5.8 kg C m-2) was not significantly different from either one. High extractable oxalate and pyrophosphate Al concentrations (varying from 20.3-24.4 g kg-1, and 3.9-11.1 g kg-1, respectively) were found in all sites. In this study, SOC and aggregate dynamics were studied using size and density fractionation experiments of the SOC, δ13C and total carbon analysis of the different SOC fractions, and C mineralization experiments. The results showed that electrostatic sorption between and among amorphous Al components and clay minerals is mainly responsible for the formation of metal-humus-clay complexes and the stabilization of soil aggregates. The process of ligand exchange between SOC and Al would be of minor importance resulting in the absence of aggregate hierarchy in this soil type. Whole soil C mineralization rate constants were highest for SGFOR and PINUS, followed by GRASS (respectively 0.495, 0.266 and 0.196 g CO2-Cm-2d-1 for the top soil layer). In contrast, incubation experiments of isolated macro organic matter fractions gave opposite results, showing that the recalcitrance of the SOC decreased in another order: PINUS>SGFOR>GRASS. We deduced that electrostatic sorption processes and physical protection of SOC in soil aggregates were the main processes determining SOC stabilization. As a result, high aggregate carbon concentrations, varying from 148 till 48 g kg-1, were encountered for all land use sites. Al

  14. Assessing the quality of soil carbon using mid-infrared spectroscopy

    Science.gov (United States)

    With an increasing focus on carbon sequestration in soils to help offset anthropogenic greenhouse gas emissions, there is a growing need for standardized methods of assessing the quality (i.e., residence time) of soil organic carbon. Information on soil carbon quality is critica...

  15. Estimating soil labile organic carbon and potential turnover rates using a sequential fumigation–incubation procedure.

    Science.gov (United States)

    X.M. Zoua; H.H. Ruanc; Y. Fua; X.D. Yanga; L.Q. Sha

    2005-01-01

    Labile carbon is the fraction of soil organic carbon with most rapid turnover times and its oxidation drives the flux of CO2 between soils and atmosphere. Available chemical and physical fractionation methods for estimating soil labile organic carbon are indirect and lack a clear biological definition. We have modified the well-established Jenkinson and Powlson’s...

  16. Soil and biomass carbon re-accumulation after landslide disturbances

    Science.gov (United States)

    Schomakers, Jasmin; Jien, Shih-Hao; Lee, Tsung-Yu; Huang-Chuan, Jr.; Hseu, Zeng-Yei; Lin, Zan Liang; Lee, Li-Chin; Hein, Thomas; Mentler, Axel; Zehetner, Franz

    2017-07-01

    In high-standing islands of the Western Pacific, typhoon-triggered landslides occasionally strip parts of the landscape of its vegetative cover and soil layer and export large amounts of biomass and soil organic carbon (OC) from land to the ocean. After such disturbances, new vegetation colonizes the landslide scars and OC starts to re-accumulate. In the subtropical mountains of Taiwan and in other parts of the world, bamboo (Bambusoideae) species may invade at a certain point in the succession of recovering landslide scars. Bamboo has a high potential for carbon sequestration because of its fast growth and dense rooting system. However, it is still largely unknown how these properties translate into soil OC re-accumulation rates after landslide disturbance. In this study, a chronosequence was established on four former landslide scars in the Central Mountain Range of Taiwan, ranging in age from 6 to 41 years post disturbance as determined by landslide mapping from remote sensing. The younger landslide scars were colonized by Miscanthus floridulus, while after approx. 15 to 20 years of succession, bamboo species (Phyllostachys) were dominating. Biomass and soil OC stocks were measured on the recovering landslide scars and compared to an undisturbed Cryptomeria japonica forest stand in the area. After initially slow re-vegetation, biomass carbon accumulated in Miscanthus stands with mean annual accretion rates of 2 ± 0.5 Mg C ha- 1 yr- 1. Biomass carbon continued to increase after bamboo invasion and reached 40% of that in the reference forest site after 41 years of landslide recovery. Soil OC accumulation rates were 2.0 Mg C ha- 1 yr- 1, 6 to 41 years post disturbance reaching 64% of the level in the reference forest. Our results from this in-situ study suggest that recovering landslide scars are strong carbon sinks once an initial lag period of vegetation re-establishment is overcome.

  17. Global carbon sequestration in tidal, saline wetland soils

    Science.gov (United States)

    Chmura, G.L.; Anisfeld, S.C.; Cahoon, D.R.; Lynch, J.C.

    2003-01-01

    Wetlands represent the largest component of the terrestrial biological carbon pool and thus play an important role in global carbon cycles. Most global carbon budgets, however, have focused on dry land ecosystems that extend over large areas and have not accounted for the many small, scattered carbon-storing ecosystems such as tidal saline wetlands. We compiled data for 154 sites in mangroves and salt marshes from the western and eastern Atlantic and Pacific coasts, as well as the Indian Ocean, Mediterranean Ocean, and Gulf of Mexico. The set of sites spans a latitudinal range from 22.4??S in the Indian Ocean to 55.5??N in the northeastern Atlantic. The average soil carbon density of mangrove swamps (0.055 ?? 0.004 g cm-3) is significantly higher than the salt marsh average (0.039 ?? 0.003 g cm-3). Soil carbon density in mangrove swamps and Spartina patens marshes declines with increasing average annual temperature, probably due to increased decay rates at higher temperatures. In contrast, carbon sequestration rates were not significantly different between mangrove swamps and salt marshes. Variability in sediment accumulation rates within marshes is a major control of carbon sequestration rates masking any relationship with climatic parameters. Globally, these combined wetlands store at least 44.6 Tg C yr-1 and probably more, as detailed areal inventories are not available for salt marshes in China and South America. Much attention has been given to the role of freshwater wetlands, particularly northern peatlands, as carbon sinks. In contrast to peatlands, salt marshes and mangroves release negligible amounts of greenhouse gases and store more carbon per unit area. Copyright 2003 by the American Geophysical Union.

  18. Advanced in-situ measurement of soil carbon content using inelastic neutron scattering

    Science.gov (United States)

    Measurement and mapping of natural and anthropogenic variations in soil carbon stores is a critical component of any soil resource evaluation process. Emerging modalities for soil carbon analysis in the field is the registration of gamma rays from soil under neutron irradiation. The inelastic neutro...

  19. Mapping Soil Organic Carbon in the U.S. Corn Belt

    Science.gov (United States)

    Soil carbon sequestration in the U.S. Con Belt was studied to evaluate the impact of land-use, soil and crop management that can play a significant role in promoting the mitigation of atmospheric CO2 and improve soil quality such as reduced erosion and also increase soil organic carbon (SOC) content...

  20. Environmental context affects microbial ecophysiological mechanisms underpinning soil carbon storage under different land use

    Science.gov (United States)

    Malik, A. A.; Puissant, J.; Buckeridge, K. M.; Goodall, T.; Jehmlich, N.; Chowdhury, S.; Gleixner, G.; Griffiths, R.

    2017-12-01

    Soil microorganisms act as gatekeepers for soil-atmosphere carbon exchange by balancing the accumulation and release of organic matter in soil. Increasing evidence now exists to suggest that microbial biomass contributes significantly to soil organic carbon formation. However, we do not fully understand the microbial mechanisms of organic matter processing and this hinders the development of effective land management strategies to enhance soil carbon storage. Here we empirically link key microbial ecophysiological traits to soil carbon storage in temperate grassland habitats ranging in land use from pristine species-rich grasslands to intensive croplands in 56 different soils across Britain. Physiological mechanisms of soil microorganisms were assessed using stable carbon isotope tracing and soil proteomics. Through spatial patterns and path analysis of structural equation modeling we discern two distinct pH-related mechanisms of soil carbon storage and highlight that the response of these mechanistic indicators is shaped by the environmental context. Land use intensification in low pH soils that increases soil pH above a threshold value ( 6.2) leads to loss of carbon due to increased microbial degradation as a result of lower acid retardation of organic matter decomposition. On the contrary, the loss of carbon through intensification in high pH (> 6.2) soils was linked to decreased microbial biomass and reduced carbon use efficiency that was linked to tradeoffs with stress alleviation and resource acquisition. We conclude that land use intensification-induced changes in soil pH can be used as a proxy to determine the effect of land management strategies on microbial soil carbon cycling processes and emphasize that more extensive land management practices at higher soil pH have greater potential for soil carbon storage through increased microbial metabolic efficiency, whereas in acidic soils abiotic factors exert a greater influence on the fate of soil carbon.

  1. Enhanced anaerobic transformations of carbon tetrachloride by soil organic matter

    Energy Technology Data Exchange (ETDEWEB)

    Collins, R.; Picardal, F.

    1999-12-01

    Anaerobic, reductive dehalogenation of carbon tetrachloride (CT) by Shewanella putrefaciens 200 is enhanced by the presence of a high-organic-carbon soil. In microbial incubations without soil, 29% of the initial 3 ppm CT was transformed after 33 h, whereas 64% was transformed after only 18 h when soil was present. In sterile, biomimetic systems using a chemical reductant, 20 mM dithiothreitol, similar results were observed, suggesting that abiotic electron-transfer mediators in the soil were catalyzing the reaction. Destruction of 62% of the soil organic carbon by H{sub 2}O{sub 2} resulted in a soil that was less effective in enhancing CT dechlorination. Following separation of the soil organic matter into three humic fractions, the humic acid (HA) fraction catalyzed the dechlorination reaction to a greater extent than did the fulvic acid (FA) fraction, and both were more effective than the fraction containing humin and inorganic minerals. The results are consistent with a mechanism involving humic functional groups that serve as electron-transfer mediators able to enhance the reductive transformation of CT in the presence of a microbial or chemical reductant. Humic functional group analyses showed that the FA contained more total acidity and carboxylic acidity than did the HA; however, both fractions contained similar amounts of total carbonyl groups and quinone carbonyls. Abiotic, HA-mediated CT transformation was observed regardless of whether dithiothreitol was present or not. At circumneutral pH, HA-mediated CT transformation required the presence of dithiothreitol. At pH 8.7, HA-mediated reductive CT transformation occurred both in the absence or presence of dithiothreitol although the transformation was greater in the presence of a reductant. Trichloromethane (chloroform [CF]) production at pH 8.7 was much lower than at circumneutral pH, and volatile organic compounds other than CF were not detected as products in any case.

  2. Nitrogen Deposition Effects on Soil Carbon Dynamics in Temperate Forests

    DEFF Research Database (Denmark)

    Ginzburg Ozeri, Shimon

    edges were used to study the effects of varying N deposition load on SOC stocks and fluxes as well as on the temperature sensitivity of SOM respiration. In a third study, the effects of 20 years of continuous experimental N addition (35 kg N ha-1 year-1) on soil C budget were investigated. Our general...... incubated in litterbags had significantly lower late-stage decomposition rates compared with control litter. However, potential respiration of forest floor and mineral soil was overall unaffected by the experimental N-additions. A temperature treatment of forest floor samples taken from one edge site......Soils contain the largest fraction of terrestrial carbon (C). Understanding the factors regulating the decomposition and storage of soil organic matter (SOM) is essential for predictions of the C sink strength of the terrestrial environment in the light of global change. Elevated long-term nitrogen...

  3. 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

  4. Moving beyond carbon bean counting: what information do we need to truly assess soil carbon sequestration?

    Science.gov (United States)

    Sanderman, J.; Fillery, I.; Roper, M.; Murphy, D.; Wang, E.

    2012-12-01

    Measuring changes in bulk soil organic carbon alone will likely not give us an accurate picture of carbon sequestration in response to a land use or land management shift. For soil carbon sequestration to be an effective greenhouse gas mitigation measure, we must understand the decadal to century scale stability of newly sequestered soil carbon. This understanding will only come from studies that ask questions such as where and in what form is SOC accumulating. Here we present results from a study examining shifts in SOC when the subtropical C4 perennial grass, kikuyu (Pennisetum clandestinium), is sown into formerly C3 annual grass dominated pastures in contrasting soil types. The C3-C4 vegetation transition provided an excellent opportunity to trace changes in the stable carbon isotope composition of SOC and its fractions to better understand the dynamics of SOC in a system that is accumulating carbon. Using a paired-plot chronosequence approach spanning 33 years, we found that in the sandy soils of Western Australia, SOC accumulated at a rate of 0.90 Mg C ha-1 yr-1 over a 30 year period, but all of this increase was found to have occurred in the particulate organic carbon fraction. In finer textured soils in South Australia over a similar time span, sequestration rates were lower, averaging 0.26 Mg C ha-1 yr-1, but one third of the new SOC was found in a mineral-associated fraction. These findings raise some interesting questions that will be explored in this presentation. Why has there been so much accumulation of SOC in the sandy soil where protection mechanisms are minimal? Do these data fit with the our current understanding of SOC dynamics? Does the concept of carbon saturation hold in a soil with 2% clay? If there were a major perturbation (i.e. long-term drought or management shift away from pasture) to the system, would the newly sequestered SOC in the fine textured soil be more resistant to loss?

  5. Soil carbon effluxes in ecosystems of Forsmark and Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Tagesson, Torbern (Dept. of Physical Geography and Ecosystem Analysis, Lund Univ. (Sweden))

    2007-12-15

    Soil carbon effluxes were estimated in a number of ecosystems in Laxemar and Forsmark investigations areas. It was done in a young Scots pine (Pinus sylvestris) stand, a wet deciduous stand, a poor fen and an agricultural field in the Laxemar investigation area in south-eastern Sweden (57 deg 5 min N, 16 deg 7 min E) and in a pasture, two Norway spruce (Picea abies) stands, a deciduous forest, a mire, a wet deciduous forest and a clear-cut in the Forsmark investigation area (60 deg 4 min N, 18 deg 2 min E). It was measured with the closed chamber technique in 2005 and 2006. Soil temperature at 10 cm depth, air temperature and photosynthetically active radiation (PAR) were also measured. Exponential regressions with soil respiration against air and soil temperature were used to estimate annual soil respiration. A hyperbolic curve with Gross Primary Production (GPP) against PAR was used for modelling GPP for the growing season in the poor fen and the agricultural area of Laxemar. The exponential regressions with soil respiration against air and soil temperature explained on average 33.6% and 44.0% of the variation, respectively. GPP of the ground vegetation were reducing soil carbon effluxes, in all stands but one of the spruce stands, the deciduous forest, the mire and the wet deciduous forest of Forsmark. The significant (all but spruce 2 in Forsmark) curves with GPP against PAR explained on average 22.7% of the variation in GPP. The cubic regressions with GPP against air temperature were only significant for the poor fen and the agricultural field in Laxemar and it explained on average 34.8% of the variation in GPP for these ecosystems. The exponential regressions with air and soil temperature against soil respiration could be used to temporally extrapolate the occasional field measurements. The hyperbolic curve with GPP against PAR could also be used for temporal extrapolation of GPP for the ecosystems without a tree layer, i.e. the poor fen and the agricultural

  6. Soil carbon effluxes in ecosystems of Forsmark and Laxemar

    International Nuclear Information System (INIS)

    Tagesson, Torbern

    2007-12-01

    Soil carbon effluxes were estimated in a number of ecosystems in Laxemar and Forsmark investigations areas. It was done in a young Scots pine (Pinus sylvestris) stand, a wet deciduous stand, a poor fen and an agricultural field in the Laxemar investigation area in south-eastern Sweden (57 deg 5 min N, 16 deg 7 min E) and in a pasture, two Norway spruce (Picea abies) stands, a deciduous forest, a mire, a wet deciduous forest and a clear-cut in the Forsmark investigation area (60 deg 4 min N, 18 deg 2 min E). It was measured with the closed chamber technique in 2005 and 2006. Soil temperature at 10 cm depth, air temperature and photosynthetically active radiation (PAR) were also measured. Exponential regressions with soil respiration against air and soil temperature were used to estimate annual soil respiration. A hyperbolic curve with Gross Primary Production (GPP) against PAR was used for modelling GPP for the growing season in the poor fen and the agricultural area of Laxemar. The exponential regressions with soil respiration against air and soil temperature explained on average 33.6% and 44.0% of the variation, respectively. GPP of the ground vegetation were reducing soil carbon effluxes, in all stands but one of the spruce stands, the deciduous forest, the mire and the wet deciduous forest of Forsmark. The significant (all but spruce 2 in Forsmark) curves with GPP against PAR explained on average 22.7% of the variation in GPP. The cubic regressions with GPP against air temperature were only significant for the poor fen and the agricultural field in Laxemar and it explained on average 34.8% of the variation in GPP for these ecosystems. The exponential regressions with air and soil temperature against soil respiration could be used to temporally extrapolate the occasional field measurements. The hyperbolic curve with GPP against PAR could also be used for temporal extrapolation of GPP for the ecosystems without a tree layer, i.e. the poor fen and the agricultural

  7. [Spatial characteristics of soil organic carbon and nitrogen storages in Songnen Plain maize belt].

    Science.gov (United States)

    Zhang, Chun-Hua; Wang, Zong-Ming; Ren, Chun-Ying; Song, Kai-Shan; Zhang, Bai; Liu, Dian-Wei

    2010-03-01

    By using the data of 382 typical soil profiles from the second soil survey at national and county levels, and in combining with 1:500000 digital soil maps, a spatial database of soil profiles was established. Based on this, the one meter depth soil organic carbon and nitrogen storage in Songnen Plain maize belt of China was estimated, with the spatial characteristics of the soil organic carbon and nitrogen densities as well as the relationships between the soil organic carbon and nitrogen densities and the soil types and land use types analyzed. The soil organic carbon and nitrogen storage in the maize belt was (163.12 +/- 26.48) Tg and (9.53 +/- 1.75) Tg, respectively, mainly concentrated in meadow soil, chernozem, and black soil. The soil organic carbon and nitrogen densities were 5.51-25.25 and 0.37-0.80 kg x m(-2), respectively, and the C/N ratio was about 7.90 -12.67. The eastern and northern parts of the belt had much higher carbon and nitrogen densities than the other parts of the belt, and upland soils had the highest organic carbon density [(19.07 +/- 2.44) kg x m(-2)], forest soils had the highest nitrogen density [(0.82 +/- 0.25) kg x m(-2)], while lowland soils had the lower organic carbon and nitrogen densities.

  8. Microbial community controls on decomposition and soil carbon storage

    Science.gov (United States)

    Frey, S. D.

    2016-12-01

    Soil is one of the most diverse habitats on Earth and one of the least characterized in terms of the identification and ecological roles of soil organisms. Soils also contain the largest repository of organic C in the terrestrial biosphere and the activities of heterotrophic soil organisms are responsible for one of the largest annual fluxes of CO2 to the atmosphere. A fundamental controversy in ecosystem ecology is the degree to which identification of microbial taxa informs our ability to understand and model ecosystem-scale processes, such as soil carbon storage and fluxes. We have evidence that microbial identity does matter, particularly in a global change context where soil microorganisms experience selective pressures to adapt to changing environments. In particular, our work at the Harvard Forest Long-term Ecological Research (LTER) site demonstrates that the microbial community is fundamentally altered by global change stressors (climate warming, nitrogen deposition, biotic invasion) and that microbial taxa exposed to long-term environmental change exhibit an altered capacity to decompose organic matter. This talk will discuss the relative importance of changes in microbial community structure versus microbial physiology for soil organic matter degradation and stabilization.

  9. Cycling of beryllium and carbon through hillslope soils in Iowa

    Science.gov (United States)

    Harden, J.W.; Fries, T.L.; Pavich, M.J.

    2002-01-01

    Isotopes of Be and C were used to reconstruct loess accumulation, hillslope evolution, and agricultural modification in soils of western Iowa. While both elements are derived from additions by the atmosphere (via plants in the case of carbon), the differences in element cycling allow erosional and depositional processes to be separated from biochemical processing. Based on 10Be, loess accumulation likely occurred simultaneously with hillslope degradation. Rates of loess accumulation declined five-fold between early stages (late Pleistocene and early Holocene) and later stages (late Holocene) of accumulation, but the absolute timing of accumulation requires independent dating methods. Based on 14C measurements, plant inputs and decomposition are significant near the surface, but below 1-1.5 m carbon inputs are minimal and decomposition is nearly arrested. The amount of carbon below 1.5 m is constant (0.1%) and is composed of soil organic matter that was buried by loess. Agricultural modification results in a dramatic redistribution of 10Be through soil erosion and deposition. By contrast, the redistribution of soil organic matter is masked by the rapid cycling of C through the topsoil as it continually decomposes and is replaced by plant inputs.

  10. Soil Organic Carbon Responses to Forest Expansion on Mountain Grasslands

    DEFF Research Database (Denmark)

    Guidi, Claudia

    Grassland abandonment followed by progressive forest expansion is the dominant land-use change in the European Alps. Contrasting trends in soil organic carbon (SOC) stocks have been reported for mountainous regions following forest expansion on grasslands. Moreover, its effects on SOC properties ...... grasslands, which can be explained by lower accumulation of binding agents of microbial origin. This can have implications for the accumulation of atmospheric CO2 in soil and for the susceptibility of SOC to external disturbances such as management and environmental changes.......Grassland abandonment followed by progressive forest expansion is the dominant land-use change in the European Alps. Contrasting trends in soil organic carbon (SOC) stocks have been reported for mountainous regions following forest expansion on grasslands. Moreover, its effects on SOC properties...... involved into long-term stability are largely unknown. The aim of this PhD thesis was to explore changes in: (i) SOC stocks; (ii) physical SOC fractions; and (iii) labile soil carbon components following forest expansion on mountain grasslands. A land-use gradient located in the Southern Alps (Italy...

  11. Critical carbon input to maintain current soil organic carbon stocks in global wheat systems.

    Science.gov (United States)

    Wang, Guocheng; Luo, Zhongkui; Han, Pengfei; Chen, Huansheng; Xu, Jingjing

    2016-01-13

    Soil organic carbon (SOC) dynamics in croplands is a crucial component of global carbon (C) cycle. Depending on local environmental conditions and management practices, typical C input is generally required to reduce or reverse C loss in agricultural soils. No studies have quantified the critical C input for maintaining SOC at global scale with high resolution. Such information will provide a baseline map for assessing soil C dynamics under potential changes in management practices and climate, and thus enable development of management strategies to reduce C footprint from farm to regional scales. We used the soil C model RothC to simulate the critical C input rates needed to maintain existing soil C level at 0.1° × 0.1° resolution in global wheat systems. On average, the critical C input was estimated to be 2.0 Mg C ha(-1) yr(-1), with large spatial variability depending on local soil and climatic conditions. Higher C inputs are required in wheat system of central United States and western Europe, mainly due to the higher current soil C stocks present in these regions. The critical C input could be effectively estimated using a summary model driven by current SOC level, mean annual temperature, precipitation, and soil clay content.

  12. Mechanisms controlling soil carbon sequestration under atmospheric nitrogen deposition

    Energy Technology Data Exchange (ETDEWEB)

    R.L. Sinsabaugh; D.R. Zak; D.L. Moorhead

    2008-02-19

    Increased atmospheric nitrogen (N) deposition can alter the processing and storage of organic carbon in soils. In 2000, we began studying the effects of simulated atmospheric N deposition on soil carbon dynamics in three types of northern temperate forest that occur across a wide geographic range in the Upper Great Lakes region. These ecosystems range from 100% oak in the overstory (black oak-white oak ecosystem; BOWO) to 0% overstory oak (sugar maple-basswood; SMBW) and include the sugar maple-red oak ecosystem (SMRO) that has intermediate oak abundance. The leaf litter biochemistry of these ecosystems range from highly lignified litter (BOWO) to litter of low lignin content (SMBW). We selected three replicate stands of each ecosystem type and established three plots in each stand. Each plot was randomly assigned one of three levels of N deposition (0, 30 & 80 kg N ha-1 y-1) imposed by adding NaNO3 in six equal increments applied over the growing season. Through experiments ranging from the molecular to the ecosystem scales, we produced a conceptual framework that describes the biogeochemistry of soil carbon storage in N-saturated ecosystems as the product of interactions between the composition of plant litter, the composition of the soil microbial community and the expression of extracellular enzyme activities. A key finding is that atmospheric N deposition can increase or decrease the soil C storage by modifying the expression of extracellular enzymes by soil microbial communities. The critical interactions within this conceptual framework have been incorporated into a new class of simulations called guild decomposition models.

  13. Fly Ash Amendments Catalyze Soil Carbon Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Amonette, James E.; Kim, Jungbae; Russell, Colleen K.; Palumbo, A. V.; Daniels, William L.

    2003-09-15

    We tested the effects of four alkaline fly ashes {Class C (sub-bituminous), Class F (bituminous), Class F [bituminous with flue-gas desulfurization (FGD) products], and Class F (lignitic)} on a reaction that simulates the enzyme-mediated formation of humic materials in soils. The presence of FGD products completely halted the reaction, and the bituminous ash showed no benefit over an ash-free control. The sub-bituminous and lignitic fly ashes, however, increased the amount of polymer formed by several-fold. The strong synergetic effect of these ashes when enzyme is present apparently arises from the combined effects of metal oxide co-oxidation (Fe and Mn oxides), alkaline pH, and physical stabilization of the enzyme (porous silica cenospheres).

  14. How accurately can soil organic carbon stocks and stock changes be quantified by soil inventories?

    Directory of Open Access Journals (Sweden)

    M. Schrumpf

    2011-05-01

    Full Text Available Precise determination of changes in organic carbon (OC stocks is prerequisite to understand the role of soils in the global cycling of carbon and to verify changes in stocks due to management. A large dataset was collected to form base to repeated soil inventories at 12 CarboEurope sites under different climate and land-use, and with different soil types. Concentration of OC, bulk density (BD, and fine earth fraction were determined to 60 cm depth at 100 sampling points per site. We investigated (1 time needed to detect changes in soil OC, assuming future re-sampling of 100 cores; (2 the contribution of different sources of uncertainties to OC stocks; (3 the effect of OC stock calculation on mass rather than volume base for change detection; and (4 the potential use of pedotransfer functions (PTF for estimating BD in repeated inventories.

    The period of time needed for soil OC stocks to change strongly enough to be detectable depends on the spatial variability of soil properties, the depth increment considered, and the rate of change. Cropland sites, having small spatial variability, had lower minimum detectable differences (MDD with 100 sampling points (105 ± 28 gC m−2 for the upper 10 cm of the soil than grassland and forest sites (206 ± 64 and 246 ± 64 gC m−2 for 0–10 cm, respectively. Expected general trends in soil OC indicate that changes could be detectable after 2–15 yr with 100 samples if changes occurred in the upper 10 cm of stone-poor soils. Error propagation analyses showed that in undisturbed soils with low stone contents, OC concentrations contributed most to OC stock variability while BD and fine earth fraction were more important in upper soil layers of croplands and in stone rich soils. Though the calculation of OC stocks based on equivalent soil masses slightly decreases the chance to detect changes with time at most sites except for the croplands, it is still recommended to

  15. Calculating carbon mass balance from unsaturated soil columns treated with CaSO₄₋minerals: test of soil carbon sequestration.

    Science.gov (United States)

    Han, Young-Soo; Tokunaga, Tetsu K

    2014-12-01

    Renewed interest in managing C balance in soils is motivated by increasing atmospheric concentrations of CO2 and consequent climate change. Here, experiments were conducted in soil columns to determine C mass balances with and without addition of CaSO4-minerals (anhydrite and gypsum), which were hypothesized to promote soil organic carbon (SOC) retention and soil inorganic carbon (SIC) precipitation as calcite under slightly alkaline conditions. Changes in C contents in three phases (gas, liquid and solid) were measured in unsaturated soil columns tested for one year and comprehensive C mass balances were determined. The tested soil columns had no C inputs, and only C utilization by microbial activity and C transformations were assumed in the C chemistry. The measurements showed that changes in C inventories occurred through two processes, SOC loss and SIC gain. However, the measured SOC losses in the treated columns were lower than their corresponding control columns, indicating that the amendments promoted SOC retention. The SOC losses resulted mostly from microbial respiration and loss of CO2 to the atmosphere rather than from chemical leaching. Microbial oxidation of SOC appears to have been suppressed by increased Ca(2+) and SO4(2)(-) from dissolution of CaSO4 minerals. For the conditions tested, SIC accumulation per m(2) soil area under CaSO4-treatment ranged from 130 to 260 g C m(-1) infiltrated water (20-120 g C m(-1) infiltrated water as net C benefit). These results demonstrate the potential for increasing C sequestration in slightly alkaline soils via CaSO4-treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Combining Soil Databases for Topsoil Organic Carbon Mapping in Europe.

    Science.gov (United States)

    Aksoy, Ece; Yigini, Yusuf; Montanarella, Luca

    2016-01-01

    Accuracy in assessing the distribution of soil organic carbon (SOC) is an important issue because of playing key roles in the functions of both natural ecosystems and agricultural systems. There are several studies in the literature with the aim of finding the best method to assess and map the distribution of SOC content for Europe. Therefore this study aims searching for another aspect of this issue by looking to the performances of using aggregated soil samples coming from different studies and land-uses. The total number of the soil samples in this study was 23,835 and they're collected from the "Land Use/Cover Area frame Statistical Survey" (LUCAS) Project (samples from agricultural soil), BioSoil Project (samples from forest soil), and "Soil Transformations in European Catchments" (SoilTrEC) Project (samples from local soil data coming from six different critical zone observatories (CZOs) in Europe). Moreover, 15 spatial indicators (slope, aspect, elevation, compound topographic index (CTI), CORINE land-cover classification, parent material, texture, world reference base (WRB) soil classification, geological formations, annual average temperature, min-max temperature, total precipitation and average precipitation (for years 1960-1990 and 2000-2010)) were used as auxiliary variables in this prediction. One of the most popular geostatistical techniques, Regression-Kriging (RK), was applied to build the model and assess the distribution of SOC. This study showed that, even though RK method was appropriate for successful SOC mapping, using combined databases was not helpful to increase the statistical significance of the method results for assessing the SOC distribution. According to our results; SOC variation was mainly affected by elevation, slope, CTI, average temperature, average and total precipitation, texture, WRB and CORINE variables for Europe scale in our model. Moreover, the highest average SOC contents were found in the wetland areas; agricultural

  17. Soil Organic Carbon Losses: The Balance between Respiration and Leaching, and Phosphorus Mobility in Lateritic Soils

    Directory of Open Access Journals (Sweden)

    Fadly Hairannoor Yusran

    2010-09-01

    Full Text Available Organic matter (OM application may contribute to managing lateritic soils by improving aspects of physical, chemical, and biological fertility. However, the finite persistence of organic carbon (OC, the main component of soil organic matter (SOM, may limit the usefulness of OM addition because decomposition and C leaching promotes C loss from the soil, especially in tropical regions. The main objectives of this study were to determine the balance and dynamics of soil OC (SOC due to mineralisation and leaching processes and the relationship of these processes to P mobility in soil. Two lateritic soils of Western Australia were used. Both soils were packed into plastic columns and water was added to simulate two rainfall regimes: tropical (4,000 mm year 1 and subtropical (900 mm year 1. Three types of OM (peat, wheat straw, and lucerne hay were added at the equivalent of 80Mg ha 1. Soils were watered weekly to supply one year’s rainfall over a period of six months. Carbon loss from leaching contributed 1.4% of the total C, whilst respiration accounted for 10.4%. The Ultisol with a sandy texture had more C loss in leachate than the Oxisol with higher clay content, for the simulated tropical rainfall. The subtropical rainfall regime resulted in more respiration than the tropical rainfall regime. Downward movement of dissolved organic carbon (DOC changed the distribution of non-extractable phosphorus (NP and bicarbonate phosphorus (BP in the leaching column, as well as the dislocation of extractable Al and Fe.

  18. Modelling carbon and nitrogen turnover in variably saturated soils

    Science.gov (United States)

    Batlle-Aguilar, J.; Brovelli, A.; Porporato, A.; Barry, D. A.

    2009-04-01

    Natural ecosystems provide services such as ameliorating the impacts of deleterious human activities on both surface and groundwater. For example, several studies have shown that a healthy riparian ecosystem can reduce the nutrient loading of agricultural wastewater, thus protecting the receiving surface water body. As a result, in order to develop better protection strategies and/or restore natural conditions, there is a growing interest in understanding ecosystem functioning, including feedbacks and nonlinearities. Biogeochemical transformations in soils are heavily influenced by microbial decomposition of soil organic matter. Carbon and nutrient cycles are in turn strongly sensitive to environmental conditions, and primarily to soil moisture and temperature. These two physical variables affect the reaction rates of almost all soil biogeochemical transformations, including microbial and fungal activity, nutrient uptake and release from plants, etc. Soil water saturation and temperature are not constants, but vary both in space and time, thus further complicating the picture. In order to interpret field experiments and elucidate the different mechanisms taking place, numerical tools are beneficial. In this work we developed a 3D numerical reactive-transport model as an aid in the investigation the complex physical, chemical and biological interactions occurring in soils. The new code couples the USGS models (MODFLOW 2000-VSF, MT3DMS and PHREEQC) using an operator-splitting algorithm, and is a further development an existing reactive/density-dependent flow model PHWAT. The model was tested using simplified test cases. Following verification, a process-based biogeochemical reaction network describing the turnover of carbon and nitrogen in soils was implemented. Using this tool, we investigated the coupled effect of moisture content and temperature fluctuations on nitrogen and organic matter cycling in the riparian zone, in order to help understand the relative

  19. Dissolved carbon leaching from soil is a crucial component of the net ecosystem carbon balance

    DEFF Research Database (Denmark)

    Kindler, Reimo; Siemens, Jan; Kaiser, Klaus

    2011-01-01

    Estimates of carbon leaching losses from different land use systems are few and their contribution to the net ecosystem carbon balance is uncertain. We investigated leaching of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and dissolved methane (CH4), at forests, grasslands......, and croplands across Europe. Biogenic contributions to DIC were estimated by means of its d13C signature. Leaching of biogenic DIC was 8.34.9 gm2 yr1 for forests, 24.17.2 gm2 yr1 for grasslands, and 14.64.8 gm2 yr1 for croplands. DOC leaching equalled 3.51.3 gm2 yr1 for forests, 5.32.0 gm2 yr1 for grasslands...... (hydr)oxides. Partial pressures of CO2 in soil air and soil pH determined DIC concentrations and fluxes, but soil solutions were often supersaturated with DIC relative to soil air CO2. Leaching losses of biogenic carbon (DOC plus biogenic DIC) from grasslands equalled 5–98% (median: 22%) of net...

  20. Stabilization of carbon in composts and biochars in relation to carbon sequestration and soil fertility

    International Nuclear Information System (INIS)

    Bolan, N.S.; Kunhikrishnan, A.; Choppala, G.K.; Thangarajan, R.; Chung, J.W.

    2012-01-01

    There have been increasing interests in the conversion of organic residues into biochars in order to reduce the rate of decomposition, thereby enhancing carbon (C) sequestration in soils. However energy is required to initiate the pyrolysis process during biochar production which can also lead to the release of greenhouse gasses. Alternative methods can be used to stabilize C in composts and other organic residues without impacting their quality. The objectives of this study include: (i) to compare the rate of decomposition among various organic amendments and (ii) to examine the effect of clay materials on the stabilization of C in organic amendments. The decomposition of a number of organic amendments (composts and biochars) was examined by monitoring the release of carbon-dioxide using respiration experiments. The results indicated that the rate of decomposition as measured by half life (t 1/2 ) varied between the organic amendments and was higher in sandy soil than in clay soil. The half life value ranged from 139 days in the sandy soil and 187 days in the clay soil for poultry manure compost to 9989 days for green waste biochar. Addition of clay materials to compost decreased the rate of decomposition, thereby increasing the stabilization of C. The half life value for poultry manure compost increased from 139 days to 620, 806 and 474 days with the addition of goethite, gibbsite and allophane, respectively. The increase in the stabilization of C with the addition of clay materials may be attributed to the immobilization of C, thereby preventing it from microbial decomposition. Stabilization of C in compost using clay materials did not impact negatively the value of composts in improving soil quality as measured by potentially mineralizable nitrogen and microbial biomass carbon in soil. - Graphical abstract: Stabilization of compost using clay materials (e.g. allophane) enhances carbon sequestration in soils. Highlights: ► Comparison of decomposition rate

  1. Human impacts on soil carbon dynamics of deep-rooted Amazonian forests and effect of land use change on the carbon cycle in Amazon soils

    Science.gov (United States)

    Nepstad, Daniel; Stone, Thomas; Davidson, Eric; Trumbore, Susan E.

    1992-01-01

    The main objective of these NASA-funded projects is to improve our understanding of land-use impacts on soil carbon dynamics in the Amazon Basin. Soil contains approximately one half of tropical forest carbon stocks, yet the fate of this carbon following forest impoverishment is poorly studied. Our mechanistics approach draws on numerous techniques for measuring soil carbon outputs, inputs, and turnover time in the soils of adjacent forest and pasture ecosystems at our research site in Paragominas, state of Para, Brazil. We are scaling up from this site-specific work by analyzing Basin-wide patterns in rooting depth and rainfall seasonality, the two factors that we believe should explain much of the variation in tropical soil carbons dynamics. In this report, we summarize ongoing measurements at our Paragominas study site, progress in employing new field data to understand soil C dynamics, and some surprising results from our regional, scale-up work.

  2. GlobalSoilMap and Global Carbon Predictions

    DEFF Research Database (Denmark)

    Hempel, Jonathan; McBratney, Alex B.; Arrouays, Dominique

    consistently produced soil property information at 100 m resolution across the world. This information will aid in solving some of the key environment and societal issues of the day, including food security, global climate change land degradation and carbon sequestration. Data would be produced using mostly......: organic carbon (g/kg), texture (sand %, silt %, clay % and coarse fragments %), pH, depth to bedrock or restrictive layer. Predictions are made at specified depths with uncertainty values assigned to each prediction. An innovative splining technique will be employed to provide a continuous prediction...

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

    Science.gov (United States)

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

    2010-05-01

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

  4. The spatial distribution of soil organic carbon in tidal wetland soils of the continental United States.

    Science.gov (United States)

    Hinson, Audra L; Feagin, Rusty A; Eriksson, Marian; Najjar, Raymond G; Herrmann, Maria; Bianchi, Thomas S; Kemp, Michael; Hutchings, Jack A; Crooks, Steve; Boutton, Thomas

    2017-12-01

    Tidal wetlands contain large reservoirs of carbon in their soils and can sequester carbon dioxide (CO 2 ) at a greater rate per unit area than nearly any other ecosystem. The spatial distribution of this carbon influences climate and wetland policy. To assist with international accords such as the Paris Climate Agreement, national-level assessments such as the United States (U.S.) National Greenhouse Gas Inventory, and regional, state, local, and project-level evaluation of CO 2 sequestration credits, we developed a geodatabase (CoBluCarb) and high-resolution maps of soil organic carbon (SOC) distribution by linking National Wetlands Inventory data with the U.S. Soil Survey Geographic Database. For over 600,000 wetlands, the total carbon stock and organic carbon density was calculated at 5-cm vertical resolution from 0 to 300 cm of depth. Across the continental United States, there are 1,153-1,359 Tg of SOC in the upper 0-100 cm of soils across a total of 24 945.9 km 2 of tidal wetland area, twice as much carbon as the most recent national estimate. Approximately 75% of this carbon was found in estuarine emergent wetlands with freshwater tidal wetlands holding about 19%. The greatest pool of SOC was found within the Atchafalaya/Vermilion Bay complex in Louisiana, containing about 10% of the U.S. total. The average density across all tidal wetlands was 0.071 g cm -3 across 0-15 cm, 0.055 g cm -3 across 0-100 cm, and 0.040 g cm -3 at the 100 cm depth. There is inherent variability between and within individual wetlands; however, we conclude that it is possible to use standardized values at a range of 0-100 cm of the soil profile, to provide first-order quantification and to evaluate future changes in carbon stocks in response to environmental perturbations. This Tier 2-oriented carbon stock assessment provides a scientific method that can be copied by other nations in support of international requirements. © 2017 John Wiley & Sons Ltd.

  5. Carbon storage in post-mining forest soil, the role of tree biomass and soil bioturbation

    Czech Academy of Sciences Publication Activity Database

    Frouz, Jan; Pižl, Václav; Cienciala, E.; Kalčík, Jiří

    2009-01-01

    Roč. 94, č. 2 (2009), s. 111-121 ISSN 0168-2563 R&D Projects: GA MŠk 2B08023; GA AV ČR 1QS600660505 Institutional research plan: CEZ:AV0Z60660521 Keywords : soil formation * bioturbation * carbon cycling Subject RIV: EH - Ecology, Behaviour Impact factor: 2.771, year: 2009

  6. Loss on Ignition: Measuring Soil Organic Carbon in Soils of the Sahel, West Africa

    Science.gov (United States)

    Traditional methods of measuring soil organic carbon (SOC) are not adequate for accurate evaluation of C sequestration nor to meet environmental safety requirements. Methods that permit accurate assessment of SOC, which are environmentally healthy, and yet feasible for use in developing countries ar...

  7. Biochar as soil amendment to improve soil quality, crop yield, and carbon sequestration

    Science.gov (United States)

    Biochar, a by-product of a thermochemical process called pyrolysis, which involves burning of any agricultural and animal waste (biomass) under high temperature and absence of oxygen. It is assumed that since biochar is very high in aromatic carbon, which persists in soil environment for very long ...

  8. Effects of different soil types in natural Mediterranean areas on soil organic carbon (SOC)

    Science.gov (United States)

    Requejo Silva, Ana; Lozano García, Beatriz; Parras Alcántara, Luis

    2017-04-01

    Effects of different soil types in natural Mediterranean areas on soil organic carbon (SOC) Ana Requejo1, Beatriz Lozano-García1, Luis Parras Alcántara1 1 Department of Agricultural Chemistry and Soil Science, Faculty of Science, Agrifood Campus of International Excellence - ceiA3, University of Córdoba, Spain. The carbon content of the atmosphere can be influenced by soils, since they can store carbon or emit large quantities of CO2. C sequestration into soils is one of the most important ecosystems services because of its role in climate regulation (IPPC, 2007). Thereof, agriculture and forestry are the only activities that can contribute to C sequestration through photosynthesis and its carbon incorporation into carbohydrates (Parras Alcántara et al., 2013). Dehesa is a multifunctional agro-sylvo-pastoral system and typical landscape of southern and central Spain and southern Portugal. It is an anthropogenic system dedicated to the combined production of black iberian pigs, a variety of foods, fuel, coal, and cork. Besides, it acts as well in the production of endangered species as wildlife habitat and as sustainable hunting areas. These dehesa areas are defined by a relationship between productivity and conservation of forest oaks, providing environmental benefits such as carbon capture and storage. The area focused in this study is the Cardeña-Montoro Nature Reserve, located within the Sierra Morena (Córdoba, South Spain). The most representative soils in Cardeña-Montoro Nature Reserve are Cambisols, Regosols, Leptosols and Fluvisols according to IUSS Working Group WRB (2006). They are characterized by a low fertility, poor physical conditions and marginal capacity for agricultural use, along with low organic matter content due to climate conditions (semiarid Mediterranean climate) and soil texture (sandy). Several studies have shown that land use affects the SOC concentration (Lozano-García et al., 2016; Khaledian et al., 2016). Based on this

  9. Priming alters soil carbon dynamics during forest succession

    Science.gov (United States)

    Qiao, Na; Xu, Xingliang; Wang, Juan; Kuzyakov, Yakov

    2017-04-01

    The mechanisms underlying soil carbon (C) dynamics during forest succession remain challenged. We examined priming of soil organic matter (SOM) decomposition along a vegetation succession: grassland, young and old-growth forests. Soil C was primed much more strongly in young secondary forest than in grassland or old-growth forest. Priming resulted in large C losses (negative net C balance) in young-forest soil, whereas C stocks increased in grassland and old-growth forest. Microbial composition assessed by phospholipid fatty acids (PLFA) and utilization of easily available organics (13C-PLFA) indicate that fungi were responsible for priming in young-forest soils. Consequently, labile C inputs released by litter decomposition and root exudation determine microbial functional groups that decompose SOM during forest succession. These findings provide novel insights into connections between SOM dynamics and stabilization with microbial functioning during forest succession and show that priming is an important mechanism for contrasting soil C dynamics in young and old-growth forests.

  10. How do soil properties and soil carbon stocks change after land abandonment in Mediterranean mountain areas?

    Science.gov (United States)

    Nadal Romero, Estela; Cammeraat, Erik; Pérez Cardiel, Estela; Lasanta, Teodoro

    2016-04-01

    Land abandonment and subsequent revegetation processes (due to secondary succession and afforestation practices) are global issues with important implications in Mediterranean mountain areas. Moreover, the effects of land use changes on soil carbon stocks are a matter of concern stated in international policy agendas on the mitigation of greenhouse emissions, and afforestation practices are increasingly viewed as an environmental restorative land use change prescription and are considered one of the most efficient carbon sequestration strategies currently available. The MED-AFFOREST project aims to gain more insight into the discussion by exploring the following central research questions: (i) what is the impact of land abandonment on soil properties? and (ii) how do soil organic carbon change after land abandonment? The main objective of this study is to assess the effects of land abandonment, land use change and afforestation practices on soil properties and soil organic carbon (SOC) dynamics. For this aim, five different land covers (bare soil, meadows, secondary succession, Pinus sylvestris (PS) and Pinus nigra (PN) afforestation), in the Central Spanish Pyrenees were analysed. Results showed that changes in soil properties after land abandonment were limited, even if afforestation practices were carried out and no differences were observed between natural succession and afforestation. The results on SOC dynamics showed that: (i) SOC contents were higher in the PN sites in the topsoil (10 cm), (ii) when all the profile was considered no significant differences were observed between meadows and PN, (iii) SOC accumulation under secondary succession is a slow process, and (iv) meadows should also be considered due to the relative importance in SOC stocks. The first step of SOC stabilization after afforestation is the formation of macro-aggregates promoted by large inputs of SOC, with a high contribution of labile organic matter. However, our respiration

  11. Raman Spectroscopy and instrumentation for monitoring soil carbon systems.

    Energy Technology Data Exchange (ETDEWEB)

    Stokes, D.L.

    2003-12-08

    This work describes developments in the application of Raman scattering and surface-enhanced Raman scattering (SERS) towards the assessment/characterization of carbon in soil. In the past, the nonspecific total carbon mass content of soil samples has generally been determined through mass loss techniques and elemental analysis. However, because of the concern over CO{sub 2} buildup in the atmosphere and its possible role in the ''Greenhouse Effect,'' there is a need for better-defined models of global cycling of carbon. As a means towards this end, there is a need to know more about the structure and functionality of organic materials in soil. Raman spectroscopy may therefore prove to be an exceptional tool in soil carbon analysis. Based on vibrational transitions of irradiated molecules, it provides structural information that is often suitable for sample identification. Furthermore, Raman scattering yields very fine spectral features which offer the potential for multicomponent sample analysis with minimal or no sample pretreatment. Although the intensity of Raman scattering is generally extremely low, the surface-enhanced Raman scattering (SERS) effect can greatly enhance Raman signals (10{sup 6}-10{sup 8} range) through the adsorption of compounds on specially roughened metal surfaces. In our laboratory, we have investigated copper, gold and silver as possible substrate metals in the fabrication of SERS substrates. These substrates have included metal-coated microparticles, metal island films, and redox-roughened metal foils. We have evaluated several laser excitation sources spanning the 515-785 nm range for both Raman and SERS analysis. For this particular study, we have selected fulvic and humic acids as models for establishing the feasibility of using Raman and SERS in soil carbon analysis. Our studies thus far have demonstrated that copper substrates perform best in the SERS detection of humic and fulvic acids, particularly when coupled

  12. 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.

  13. Nutrients and defoliation increase soil carbon inputs in grassland.

    Science.gov (United States)

    Ziter, Carly; MacDougall, Andrew S

    2013-01-01

    Given the regulatory impact of resources and consumers on plant production, decomposition, and soil carbon sequestration, anthropogenic changes to nutrient inputs and grazing have likely transformed how grasslands process atmospheric CO2. The direction and magnitude of these changes, however, remain unclear in this system, whose soils contain -20% of the world's carbon pool. Nutrients stimulate production but can also increase tissue palatability and decomposition. Grazing variously affects tissue quality and quantity, decreasing, standing biomass, but potentially increasing leaf nutrient concentrations, root production, or investment in tissue defenses that slow litter decay. Here, we quantified individual and interactive impacts of nutrient addition and simulated grazing (mowing) on above- and belowground production, tissue quality, and soil carbon inputs in a western North American grassland with globally distributed agronomic species. Given that nutrients and grazing are often connected with increased root production and higher foliar tissue quality, we hypothesized that these treatments would combine to reduce inputs of recalcitrant-rich litter critical for C storage. This hypothesis was unsupported. Nutrients and defoliation combined to significantly increase belowground production but did not affect root tissue quality. There were no significant interactions between nutrients and defoliation for any measured response. Three years of nutrient addition increased root and shoot biomass by 37% and 23%, respectively, and had no impact on decomposition, resulting in a -15% increase in soil organic matter and soil carbon. Defoliation triggered a significant burst of short-lived lignin-rich roots, presumably a compensatory response to foliar loss, which increased root litter inputs by 33%. The majority of root and shoot responses were positively correlated, with aboveground biomass a reasonable proxy for whole plant responses. The exceptions were decomposition, with

  14. Soil organic carbon assessments in cropping systems using isotopic techniques

    Science.gov (United States)

    Martín De Dios Herrero, Juan; Cruz Colazo, Juan; Guzman, María Laura; Saenz, Claudio; Sager, Ricardo; Sakadevan, Karuppan

    2016-04-01

    Introduction of improved farming practices are important to address the challenges of agricultural production, food security, climate change and resource use efficiency. The integration of livestock with crops provides many benefits including: (1) resource conservation, (2) ecosystem services, (3) soil quality improvements, and (4) risk reduction through diversification of enterprises. Integrated crop livestock systems (ICLS) with the combination of no-tillage and pastures are useful practices to enhance soil organic carbon (SOC) compared with continuous cropping systems (CCS). In this study, the SOC and its fractions in two cropping systems namely (1) ICLS, and (2) CCS were evaluated in Southern Santa Fe Province in Argentina, and the use of delta carbon-13 technique and soil physical fractionation were evaluated to identify sources of SOC in these systems. Two farms inside the same soil cartographic unit and landscape position in the region were compared. The ICLS farm produces lucerne (Medicago sativa Merrill) and oat (Avena sativa L.) grazed by cattle alternatively with grain summer crops sequence of soybean (Glicine max L.) and corn (Zea mays L.), and the farm under continuous cropping system (CCS) produces soybean and corn in a continuous sequence. The soil in the area is predominantly a Typic Hapludoll. Soil samples from 0-5 and 0-20 cm depths (n=4) after the harvest of grain crops were collected in each system and analyzed for total organic carbon (SOC, 0-2000 μm), particulate organic carbon (POC, 50-100 μm) and mineral organic carbon (MOC, statistical analysis were carried out for all data. The SOC was higher in ICLS than in CCS at both depths (20.8 vs 17.7 g kg-1 for 0-5 cm and 16.1 vs 12.7 g kg-1 at 0-20 cm, respectively, P<0.05). MOC was similar at both depths, and POC was higher in CCS than in ICLS at 0-5 cm, while at 0-20 cm this trend was opposite. This is probably due to the presence of deep roots under pastures in ICLS. Delta carbon-13 values for

  15. High salinity leads to accumulation of soil organic carbon in mangrove soil.

    Science.gov (United States)

    Kida, Morimaru; Tomotsune, Mitsutoshi; Iimura, Yasuo; Kinjo, Kazutoshi; Ohtsuka, Toshiyuki; Fujitake, Nobuhide

    2017-06-01

    Although mangrove forests are one of the most well-known soil organic carbon (SOC) sinks, the mechanism underlying SOC accumulation is relatively unknown. High net primary production (NPP) along with the typical bottom-heavy biomass allocation and low soil respiration (SR) have been considered to be responsible for SOC accumulation. However, an emerging paradigm postulates that SR is severely underestimated because of the leakage of dissolved inorganic carbon (DIC) in groundwater. Here we propose a simple yet unique mechanism for SOC accumulation in mangrove soils. We conducted sequential extraction of water extractable organic matter (WEOM) from mangrove soils using ultrapure water and artificial seawater, respectively. A sharp increase in humic substances (HS) concentration was observed only in the case of ultrapure water, along with a decline in salinity. Extracted WEOM was colloidal, and ≤70% of it re-precipitated by the addition of artificial seawater. These results strongly suggest that HS is selectively flocculated and maintained in the mangrove soils because of high salinity. Because sea salts are a characteristic of any mangrove forest, high salinity may be one of mechanisms underlying SOC accumulation in mangrove soils. Copyright © 2017. Published by Elsevier Ltd.

  16. LAND USE EFFECTS ON SOIL ORGANIC CARBON AND NITROGEN IN SOME SOILS OF BALE, SOUTHEASTERN ETHIOPIA

    Directory of Open Access Journals (Sweden)

    Yifru Abera

    2010-11-01

    Full Text Available Agricultural and economic growth in Ethiopia are constrained by the deteriorating natural resource base, especially in the highlands where 80% of the population lives. This threat stems from the depletion and degradation of the vegetation cover of the country, especially forests and unsustainable farming practices. This study investigated the effects of different land-uses on soil organic carbon and total nitrogen. Both, soil organic carbon (SOC and total nitrogen (TN were responsive to land use change. Considering the top 0-5 cm depth, the highest SOC (12.95% and TN (0.8% were recorded in natural forest while the least, 2.56 and 0.21%, respectively from cultivated lands. The lowest SOC content in cultivated soils could be due to reduced inputs of organic matter and frequent tillage which encouraged oxidation of organic matter. SOC and TN consistently declined with increasing soil depth in all land use systems. The SOC and TN content calls for restoration of soil organic matter through sustainable soil management.

  17. [Effects of climate change on forest soil organic carbon storage: a review].

    Science.gov (United States)

    Zhou, Xiao-yu; Zhang, Cheng-yi; Guo, Guang-fen

    2010-07-01

    Forest soil organic carbon is an important component of global carbon cycle, and the changes of its accumulation and decomposition directly affect terrestrial ecosystem carbon storage and global carbon balance. Climate change would affect the photosynthesis of forest vegetation and the decomposition and transformation of forest soil organic carbon, and further, affect the storage and dynamics of organic carbon in forest soils. Temperature, precipitation, atmospheric CO2 concentration, and other climatic factors all have important influences on the forest soil organic carbon storage. Understanding the effects of climate change on this storage is helpful to the scientific management of forest carbon sink, and to the feasible options for climate change mitigation. This paper summarized the research progress about the distribution of organic carbon storage in forest soils, and the effects of elevated temperature, precipitation change, and elevated atmospheric CO2 concentration on this storage, with the further research subjects discussed.

  18. Selective Sorption of Dissolved Organic Carbon Compounds by Temperate Soils

    Science.gov (United States)

    Jagadamma, Sindhu; Mayes, Melanie A.; Phillips, Jana R.

    2012-01-01

    Background Physico-chemical sorption onto soil minerals is one of the major processes of dissolved organic carbon (OC) stabilization in deeper soils. The interaction of DOC on soil solids is related to the reactivity of soil minerals, the chemistry of sorbate functional groups, and the stability of sorbate to microbial degradation. This study was conducted to examine the sorption of diverse OC compounds (D-glucose, L-alanine, oxalic acid, salicylic acid, and sinapyl alcohol) on temperate climate soil orders (Mollisols, Ultisols and Alfisols). Methodology Equilibrium batch experiments were conducted using 0–100 mg C L−1 at a solid-solution ratio of 1∶60 for 48 hrs on natural soils and on soils sterilized by γ-irradiation. The maximum sorption capacity, Qmax and binding coefficient, k were calculated by fitting to the Langmuir model. Results Ultisols appeared to sorb more glucose, alanine, and salicylic acid than did Alfisols or Mollisols and the isotherms followed a non-linear pattern (higher k). Sterile experiments revealed that glucose and alanine were both readily degraded and/or incorporated into microbial biomass because the observed Qmax under sterile conditions decreased by 22–46% for glucose and 17–77% for alanine as compared to non-sterile conditions. Mollisols, in contrast, more readily reacted with oxalic acid (Qmax of 886 mg kg−1) and sinapyl alcohol (Qmax of 2031 mg kg−1), and no degradation was observed. The reactivity of Alfisols to DOC was intermediate to that of Ultisols and Mollisols, and degradation followed similar patterns as for Ultisols. Conclusion This study demonstrated that three common temperate soil orders experienced differential sorption and degradation of simple OC compounds, indicating that sorbate chemistry plays a significant role in the sorptive stabilization of DOC. PMID:23209742

  19. Anthropogenic nitrogen deposition enhances carbon sequestration in boreal soils.

    Science.gov (United States)

    Maaroufi, Nadia I; Nordin, Annika; Hasselquist, Niles J; Bach, Lisbet H; Palmqvist, Kristin; Gundale, Michael J

    2015-08-01

    It is proposed that carbon (C) sequestration in response to reactive nitrogen (Nr ) deposition in boreal forests accounts for a large portion of the terrestrial sink for anthropogenic CO2 emissions. While studies have helped clarify the magnitude by which Nr deposition enhances C sequestration by forest vegetation, there remains a paucity of long-term experimental studies evaluating how soil C pools respond. We conducted a long-term experiment, maintained since 1996, consisting of three N addition levels (0, 12.5, and 50 kg N ha(-1) yr(-1) ) in the boreal zone of northern Sweden to understand how atmospheric Nr deposition affects soil C accumulation, soil microbial communities, and soil respiration. We hypothesized that soil C sequestration will increase, and soil microbial biomass and soil respiration will decrease, with disproportionately large changes expected compared to low levels of N addition. Our data showed that the low N addition treatment caused a non-significant increase in the organic horizon C pool of ~15% and a significant increase of ~30% in response to the high N treatment relative to the control. The relationship between C sequestration and N addition in the organic horizon was linear, with a slope of 10 kg C kg(-1) N. We also found a concomitant decrease in total microbial and fungal biomasses and a ~11% reduction in soil respiration in response to the high N treatment. Our data complement previous data from the same study system describing aboveground C sequestration, indicating a total ecosystem sequestration rate of 26 kg C kg(-1) N. These estimates are far lower than suggested by some previous modeling studies, and thus will help improve and validate current modeling efforts aimed at separating the effect of multiple global change factors on the C balance of the boreal region. © 2015 John Wiley & Sons Ltd.

  20. Litter decay controlled by temperature, not soil properties, affecting future soil carbon.

    Science.gov (United States)

    Gregorich, Edward G; Janzen, Henry; Ellert, Benjamin H; Helgason, Bobbi L; Qian, Budong; Zebarth, Bernie J; Angers, Denis A; Beyaert, Ronald P; Drury, Craig F; Duguid, Scott D; May, William E; McConkey, Brian G; Dyck, Miles F

    2017-04-01

    Widespread global changes, including rising atmospheric CO 2 concentrations, climate warming and loss of biodiversity, are predicted for this century; all of these will affect terrestrial ecosystem processes like plant litter decomposition. Conversely, increased plant litter decomposition can have potential carbon-cycle feedbacks on atmospheric CO 2 levels, climate warming and biodiversity. But predicting litter decomposition is difficult because of many interacting factors related to the chemical, physical and biological properties of soil, as well as to climate and agricultural management practices. We applied 13 C-labelled plant litter to soil at ten sites spanning a 3500-km transect across the agricultural regions of Canada and measured its decomposition over five years. Despite large differences in soil type and climatic conditions, we found that the kinetics of litter decomposition were similar once the effect of temperature had been removed, indicating no measurable effect of soil properties. A two-pool exponential decay model expressing undecomposed carbon simply as a function of thermal time accurately described kinetics of decomposition. (R 2  = 0.94; RMSE = 0.0508). Soil properties such as texture, cation exchange capacity, pH and moisture, although very different among sites, had minimal discernible influence on decomposition kinetics. Using this kinetic model under different climate change scenarios, we projected that the time required to decompose 50% of the litter (i.e. the labile fractions) would be reduced by 1-4 months, whereas time required to decompose 90% of the litter (including recalcitrant fractions) would be reduced by 1 year in cooler sites to as much as 2 years in warmer sites. These findings confirm quantitatively the sensitivity of litter decomposition to temperature increases and demonstrate how climate change may constrain future soil carbon storage, an effect apparently not influenced by soil properties. © 2016 Her Majesty

  1. The use of soil monitoring networks to detect changes in soil organic carbon content

    Science.gov (United States)

    Keller, A.; Schwierz, C.; Schwab, P.; Ammann, S.; Meuli, R.; Rossier, N.; Papritz, A.

    2010-05-01

    Process-based carbon dynamic models are widely used to estimate and forecast temporal changes in soil organic carbon content (SOC). Often, these models are calibrated against measurements from long-term field experiments with controlled treatments at a local scale. Repeated SOC inventories at the sites of a soil monitoring network may provide additional valuable information about temporal changes at a regional scale for a broader range of environmental conditions (land use, soil type, climate, etc.). Recently, Saby et al. (2008) assessed the adequacy of European soil monitoring networks to detect changes in SOC. The minimum detectable changes (MDC) differed considerably among the networks, and the design turned out to be an important factor. However, Saby et al. derived their results from scenarios because the majority of the European monitoring networks performed only one sampling campaign so far. Data on SOC changes, gathered by repeated sampling at monitoring sites under controlled conditions including strict quality assurance protocols, are still rare, and little is known about random and systematic errors in the estimated changes. Furthermore, suitable (geo-) statistical procedures are required to extrapolate the SOC measurements and their change from the surveyed sites to the regional scale. In our presentation, we report (i) our experiences on MDC gained by repeated SOC measurements at selected sites of the Swiss Soil Monitoring Network (NABO), and (ii) we show how the SOC measurements recorded at the sites of the soil monitoring network of Canton Fribourg can be used for a mapping SOC and its change at the regional scale. For this purpose we a use robust geostatistical kriging approach which exploits the dependence of SOC on land use, altitude and climate. Saby P.A. et al. (2008). Will European soil-monitoring networks be able to detect changes in topsoil organic carbon content? Global Change Biology 14: 2432-2442.

  2. Regionalization of Uncovered Agricultural Soils Based on Organic Carbon and Soil Texture Estimations

    Directory of Open Access Journals (Sweden)

    Martin Kanning

    2016-11-01

    Full Text Available The determination of soil texture and organic carbon across agricultural areas provides important information to derive soil condition. Precise digital soil maps can help to till agricultural fields with more accuracy, greater cost-efficiency and better environmental protection. In the present study, the laboratory analysis of sand, silt, clay and soil organic carbon (SOC content was combined with hyperspectral image data to estimate the distribution of soil texture and SOC across an agricultural area. The aim was to identify regions with similar soil properties and derive uniform soil regions based on this information. Soil parameter data and corresponding laboratory spectra were used to calibrate cross-validated (leave-one-out partial least squares regression (PLSR models, resulting in robust models for sand (R2 = 0.77, root-mean-square error (RMSE = 5.37 and SOC (R2 = 0.89, RMSE = 0.27, as well as moderate models for silt (R2 = 0.62, RMSE = 5.46 and clay (R2 = 0.53, RMSE = 2.39. The regression models were applied to Airborne Imaging Spectrometer for Applications DUAL (aisaDUAL hyperspectral image data to spatially estimate the concentration of these parameters. Afterwards, a decision tree, based on the Food and Agriculture Organization (FAO soil texture classification scheme, was developed to determine the soil texture for each pixel of the hyperspectral airborne data. These soil texture regions were further refined with the spatial SOC estimations. The developed method is useful to identify spatial regions with similar soil properties, which can provide a vital information source for an adapted treatment of agricultural fields in terms of the necessary amount of fertilizers or water. The approach can also be adapted to wider regions with a larger sample size to create detailed digital soil maps (DSMs. Further, the presented method should be applied to future hyperspectral satellite missions like Environmental Mapping and Analysis Program (En

  3. Deep horizons: Soil Carbon sequestration and storage potential in grassland soils

    Science.gov (United States)

    Torres-Sallan, Gemma; Schulte, Rogier; Lanigan, Gary J.; Byrne, Kenneth A.; Reidy, Brian; Creamer, Rachel

    2016-04-01

    Soil Organic Carbon (SOC) enhances soil fertility, holding nutrients in a plant-available form. It also improves aeration and water infiltration. Soils are considered a vital pool for C (Carbon) sequestration, as they are the largest pool of C after the oceans, and contain 3.5 more C than the atmosphere. SOC models and inventories tend to focus on the top 30 cm of soils, only analysing total SOC values. Association of C with microaggregates (53-250 μm) and silt and clay (collected for each horizon, sieved at 8 mm and dried at 40 °C. Through a wet sieving procedure, four aggregate sizes were isolated: large macroaggregates (>2000 μm); macroaggregates (250-2000 μm); microaggregates and silt & clay. Organic C associated to each aggregate fraction was analysed on a LECO combustion analyser. Sand-free C was calculated for each aggregate size. For all soil types, 84% of the SOC located in the first 30 cm was contained inside macroaggregates and large macroaggregates. Given that this fraction has a turnover time of 1 to 10 years, sampling at that depth only provides information on the labile fraction in soil, and does not consider the longer term C sequestration potential. Only when looking at the whole profile, two clear trends could be observed: 1) soils with a clay increase at depth had most of their C located in the silt and clay fractions, which indicate their enhanced C sequestration capacity, 2) free-draining soils had a bigger part of their SOC located in the macroaggregate fractions. These results indicate that current C inventories and models that focus on the top 30 cm, do not accurately measure soil C sequestration potential in soils, but rather the more labile fraction. However, at depth soil forming processes have been identified as a major factor influencing C sequestration potential in soils. This has a major impact in further quantifying and sustaining C sequestration into the future. Soils with a high sequestration potential at depth need to be

  4. The role of soil pH on soil carbonic anhydrase activity

    Science.gov (United States)

    Sauze, Joana; Jones, Sam P.; Wingate, Lisa; Wohl, Steven; Ogée, Jérôme

    2018-01-01

    Carbonic anhydrases (CAs) are metalloenzymes present in plants and microorganisms that catalyse the interconversion of CO2 and water to bicarbonate and protons. Because oxygen isotopes are also exchanged during this reaction, the presence of CA also modifies the contribution of soil and plant CO18O fluxes to the global budget of atmospheric CO18O. The oxygen isotope signatures (δ18O) of these fluxes differ as leaf water pools are usually more enriched than soil water pools, and this difference is used to partition the net CO2 flux over land into soil respiration and plant photosynthesis. Nonetheless, the use of atmospheric CO18O as a tracer of land surface CO2 fluxes requires a good knowledge of soil CA activity. Previous studies have shown that significant differences in soil CA activity are found in different biomes and seasons, but our understanding of the environmental and ecological drivers responsible for the spatial and temporal patterns observed in soil CA activity is still limited. One factor that has been overlooked so far is pH. Soil pH is known to strongly influence microbial community composition, richness and diversity in addition to governing the speciation of CO2 between the different carbonate forms. In this study we investigated the CO2-H2O isotopic exchange rate (kiso) in six soils with pH varying from 4.5 to 8.5. We also artificially increased the soil CA concentration to test how pH and other soil properties (texture and phosphate content) affected the relationship between kiso and CA concentration. We found that soil pH was the primary driver of kiso after CA addition and that the chemical composition (i.e. phosphate content) played only a secondary role. We also found an offset between the δ18O of the water pool with which CO2 equilibrates and total soil water (i.e. water extracted by vacuum distillation) that varied with soil texture. The reasons for this offset are still unknown.

  5. Modelling soil carbon fate under erosion process in vineyard

    Science.gov (United States)

    Novara, Agata; Scalenghe, Riccardo; Minacapilli, Mario; Maltese, Antonino; Capodici, Fulvio; Borgogno Mondino, Enrico; Gristina, Luciano

    2017-04-01

    Soil erosion processes in vineyards beyond water runoff and sediment transport have a strong effect on soil organic carbon loss (SOC) and redistribution along the slope. The variation of SOC across the landscape determines a difference in soil fertility and vine productivity. The aim of this research was to study erosion of a Mediterranean vineyard, develop an approach to estimate the SOC loss, correlate the vines vigor with sediment and carbon erosion. The study was carried out in a Sicilian (Italy) vineyard, planted in 2011. Along the slope, six pedons were studied by digging 6 pits up to 60cm depth. Soil was sampled in each pedon every 10cm and SOC was analyzed. Soil erosion, detachment and deposition areas were measured by pole height method. The vigor of vegetation was expressed in term of NDVI (Normalized difference Vegetation Index) derived from a satellite image (RapidEye) acquired at berry pre-veraison stage (July) and characterized by 5 spectral bands in the shortwave region, including a band in the red wavelength (R, 630-685 nm) and in the near infrared (NIR, 760-850 nm) . Results showed that soil erosion, sediments redistribution and SOC across the hill was strongly affected by topographic features, slope and curvature. The erosion rate was 46Mg ha-1 y-1 during the first 6 years since planting. The SOC redistribution was strongly correlated with the detachment or deposition area as highlighted by pole height measurements. The approach developed to estimate the SOC loss showed that during the whole study period the off-farm SOC amounts to 1.6Mg C ha-1. As highlighted by NDVI results, the plant vigor is strong correlated with SOC content and therefore, developing an accurate NDVI approach could be useful to detect the vineyard areas characterized by low fertility due to erosion process.

  6. Non-destructive estimates of soil carbonic anhydrase activity and associated soil water oxygen isotope composition

    Science.gov (United States)

    Jones, Sam P.; Ogée, Jérôme; Sauze, Joana; Wohl, Steven; Saavedra, Noelia; Fernández-Prado, Noelia; Maire, Juliette; Launois, Thomas; Bosc, Alexandre; Wingate, Lisa

    2017-12-01

    The contribution of photosynthesis and soil respiration to net land-atmosphere carbon dioxide (CO2) exchange can be estimated based on the differential influence of leaves and soils on budgets of the oxygen isotope composition (δ18O) of atmospheric CO2. To do so, the activity of carbonic anhydrases (CAs), a group of enzymes that catalyse the hydration of CO2 in soils and plants, needs to be understood. Measurements of soil CA activity typically involve the inversion of models describing the δ18O of CO2 fluxes to solve for the apparent, potentially catalysed, rate of CO2 hydration. This requires information about the δ18O of CO2 in isotopic equilibrium with soil water, typically obtained from destructive, depth-resolved sampling and extraction of soil water. In doing so, an assumption is made about the soil water pool that CO2 interacts with, which may bias estimates of CA activity if incorrect. Furthermore, this can represent a significant challenge in data collection given the potential for spatial and temporal variability in the δ18O of soil water and limited a priori information with respect to the appropriate sampling resolution and depth. We investigated whether we could circumvent this requirement by inferring the rate of CO2 hydration and the δ18O of soil water from the relationship between the δ18O of CO2 fluxes and the δ18O of CO2 at the soil surface measured at different ambient CO2 conditions. This approach was tested through laboratory incubations of air-dried soils that were re-wetted with three waters of different δ18O. Gas exchange measurements were made on these soils to estimate the rate of hydration and the δ18O of soil water, followed by soil water extraction to allow for comparison. Estimated rates of CO2 hydration were 6.8-14.6 times greater than the theoretical uncatalysed rate of hydration, indicating that CA were active in these soils. Importantly, these estimates were not significantly different among water treatments, suggesting

  7. Landscape controls and vertical variability of soil organic carbon storage in permafrost-affected soils of the Lena River Delta

    DEFF Research Database (Denmark)

    Siewert, Matthias Benjamin; Hugelius, Gustaf; Heim, Birgit

    2016-01-01

    To project the future development of the soil organic carbon (SOC) storage in permafrost environments, the spatial and vertical distribution of key soil properties and their landscape controls needs to be understood. This article reports findings from the Arctic Lena River Delta where we sampled 50...... soil pedons. These were classified according to the U.S.D.A. Soil Taxonomy and fall mostly into the Gelisol soil order used for permafrost-affected soils. Soil profiles have been sampled for the active layer (mean depth 58 ± 10 cm) and the upper permafrost to one meter depth. We analyze SOC stocks...

  8. Impact of carbonate on the efficiency of heavy metal removal from kaolinite soil by the electrokinetic soil remediation method

    International Nuclear Information System (INIS)

    Ouhadi, V.R.; Yong, R.N.; Shariatmadari, N.; Saeidijam, S.; Goodarzi, A.R.; Safari-Zanjani, M.

    2010-01-01

    While the feasibility of using electrokinetics to decontaminate soils has been studied by several authors, the effects of soil composition on the efficiency of this method of decontamination has yet to be fully studied. This study focuses its attention on the effect of 'calcite or carbonate' (CaCO 3 ) on removal efficiency in electrokinetic soil remediation. Bench scale experiments were conducted on two soils: kaolinite and natural-soil of a landfill in Hamedan, Iran. Prescribed quantities of carbonates were mixed with these soils which were subsequently contaminated with zinc nitrate. After that, electrokinetic experiments were conducted to determine the efficiency of electrokinetic remediation. The results showed that an increase in the quantity of carbonate caused a noticeable increase on the contaminant retention of soil and on the resistance of soil to the contaminant removal by electrokinetic method. Because the presence of carbonates in the soil increases its buffering capacity, acidification is reduced, resulting in a decrease in the rate of heavy metal removed from the contaminant soil. This conclusion was validated by the evaluation of efficiency of electrokinetic method on a soil sample from the liner of a waste disposal site, with 28% carbonates.

  9. Riparian reforestation: are there changes in soil carbon and soil microbial communities?

    Science.gov (United States)

    Mackay, J E; Cunningham, S C; Cavagnaro, T R

    2016-10-01

    Reforestation of pastures in riparian zones has the potential to decrease nutrient runoff into waterways, provide both terrestrial and aquatic habitat, and help mitigate climate change by sequestering carbon (C). Soil microbes can play an important role in the soil C cycle, but are rarely investigated in studies on C sequestration. We surveyed a chronosequence (0-23years) of mixed-species plantings in riparian zones to investigate belowground (chemical and biological) responses to reforestation. For each planting, an adjacent pasture was surveyed to account for differences in soil type and land-use history among plantings. Two remnant woodlands were included in the survey as indicators of future potential of plantings. Both remnant woodlands had significantly higher soil organic C (SOC) content compared with their adjacent pastures. However, there was no clear trend in SOC content among plantings with time since reforestation. The substantial variability in SOC sequestration among plantings was possibly driven by differences in soil moisture among plantings and the inherent variability of SOC content among reference pastures adjacent to plantings. Soil microbial phospholipid fatty acids (PLFA, an indicator of microbial biomass) and activities of decomposition enzymes (β-glucosidase and polyphenol oxidase) did not show a clear trend with increasing planting age. Despite this, there were positive correlations between total SOC concentration and microbial indicators (total PLFA, fungal PLFA, bacterial PLFA and activities of decomposition enzymes) across all sites. The soil microbial community compositions (explored using PLFA markers) of older plantings were similar to those of remnant woodlands. There was a positive correlation between the soil carbon:nitrogen (C:N) and fungal:bacterial (F:B) ratios. These data indicate that in order to maximise SOC sequestration, we need to take into account not only C inputs, but the microbial processes that regulate SOC cycling

  10. Soil carbon management in large-scale Earth system modelling

    DEFF Research Database (Denmark)

    Olin, S.; Lindeskog, M.; Pugh, T. A. M.

    2015-01-01

    Croplands are vital ecosystems for human well-being and provide important ecosystem services such as crop yields, retention of nitrogen and carbon storage. On large (regional to global)-scale levels, assessment of how these different services will vary in space and time, especially in response......, carbon sequestration and nitrogen leaching from croplands are evaluated and discussed. Compared to the version of LPJ-GUESS that does not include land-use dynamics, estimates of soil carbon stocks and nitrogen leaching from terrestrial to aquatic ecosystems were improved. Our model experiments allow us...... modelling C–N interactions in agricultural ecosystems under future environmental change and the effects these have on terrestrial biogeochemical cycles....

  11. Exploring the Role of Plant Genetics to Enhance Soil Carbon Sequestration in Hybrid Poplar Plantations

    Science.gov (United States)

    Wullschleger, S. D.; Garten, C. T.; Classen, A. T.

    2008-12-01

    Atmospheric CO2 concentrations have increased in recent decades and are projected to increase even further during the coming century. These projections have prompted scientists and policy-makers to consider how plants and soils can be used to stabilize CO2 concentrations. Although storing carbon in terrestrial ecosystems represents an attractive near-term option for mitigating rising atmospheric CO2 concentrations, enhancing the sequestration potential of managed systems will require advancements in understanding the fundamental mechanisms that control rates of carbon transfer and turnover in plants and soils. To address this challenge, a mathematical model was constructed to evaluate how changes in particular plant traits and management practices could affect soil carbon storage beneath hybrid poplar (Populus) plantations. The model was built from four sub-models that describe aboveground biomass, root biomass, soil carbon dynamics, and soil nitrogen transformations for trees growing throughout a user-defined rotation. Simulations could be run over one or multiple rotations. A sensitivity analysis of the model indicated changes in soil carbon storage were affected by variables that could be linked to hybrid poplar traits like rates of aboveground production, partitioning of carbon to coarse and fine roots, and rates of root decomposition. A higher ratio of belowground to aboveground production was especially important and correlated directly with increased soil carbon storage. Faster decomposition rates for coarse and fine dead roots resulted in a greater loss of carbon to the atmosphere as CO2 and less residual organic carbon for transfer to the fast soil carbon pool. Hence, changes in root chemistry that prolonged dead root decomposition rates, a trait that is under potential genetic control, were predicted to increase soil carbon storage via higher soil carbon inputs. Nitrogen limitation of both aboveground biomass production and soil carbon sequestration was

  12. Timescales of carbon turnover in soils with mixed crystalline mineralogies

    Science.gov (United States)

    Khomo, Lesego; Trumbore, Susan E.; Bern, Carleton R.; Chadwick, Oliver A.

    2017-01-01

    Organic matter–mineral associations stabilize much of the carbon (C) stored globally in soils. Metastable short-range-order (SRO) minerals such as allophane and ferrihydrite provide one mechanism for long-term stabilization of organic matter in young soil. However, in soils with few SRO minerals and a predominance of crystalline aluminosilicate or Fe (and Al) oxyhydroxide, C turnover should be governed by chemisorption with those minerals. Here, we correlate mineral composition from soils containing small amounts of SRO minerals with mean turnover time (TT) of C estimated from radiocarbon (14C) in bulk soil, free light fraction and mineral-associated organic matter. We varied the mineral amount and composition by sampling ancient soils formed on different lithologies in arid to subhumid climates in Kruger National Park (KNP), South Africa. Mineral contents in bulk soils were assessed using chemical extractions to quantify Fe oxyhydroxides and SRO minerals. Because of our interest in the role of silicate clay mineralogy, particularly smectite (2 : 1) and kaolinite (1 : 1), we separately quantified the mineralogy of the clay-sized fraction using X-ray diffraction (XRD) and measured 14C on the same fraction. Density separation demonstrated that mineral associated C accounted for 40–70 % of bulk soil organic C in A and B1 horizons for granite, nephelinite and arid-zone gabbro soils, and > 80 % in other soils. Organic matter strongly associated with the isolated clay-sized fraction represented only 9–47 % of the bulk soil C. The mean TT of C strongly associated with the clay-sized fraction increased with the amount of smectite (2 : 1 clays); in samples with > 40 % smectite it averaged 1020 ± 460 years. The C not strongly associated with clay-sized minerals, including a combination of low-density C, the C associated with minerals of sizes between 2 µm and 2 cm (including Fe oxyhydroxides as coatings), and C removed from clay

  13. Assessing Fossil and New Carbon in Reclaimed Mined Soils

    Energy Technology Data Exchange (ETDEWEB)

    Rattan Lal; David Ussiri

    2008-09-30

    Soil organic carbon (SOC) pool in the reclaimed minesoils (RMS) is the mixture of coal C originating from mining and reclamation activities and recent plant-derived organic carbon (OC). Accurate estimates of OC pools and sequestration rates in the RMS are limited by lack of standard and cost-effective method for determination of coal-C concentration. The main objective of this project was to develop and test analytical procedures for quantifying pool sizes of coal-derived C in RMS and to partition organic C in RMS into coal-derived and newly deposited SOC fractions. Analysis of soil and coal artificial mixtures indicated that the {Delta}{sup 13}C method developed was very effective in estimating coal C added in the mixtures, especially soils under C4 plants. However, most of the reclaimed sites in Ohio are under C3 plants with range of {Delta}{sup 13}C signal falling within ranges of coal. The wide range of {Delta}{sup 13}C signal observed in minesoils, (i.e. -26 to -30 for plants and -23 to -26 for coal) limits the ability of this approach to be used for southeast Ohio minesoils. This method is applicable for reclaimed prime farm land under long term corn or corn soybean rotation. Chemi-thermal method was very effective in quantifying coal-C fraction in both soil-coal artificial mixtures and minesoils. The recovery of coal-C from the mixture ranged from 93 to 100% of coal. Cross-validation of chemi-thermal method with radiocarbon analysis revealed that chemi-thermal method was as effective as radiocarbon analysis in quantifying coal-C in RMS. Coal C determined after chemi-thermal treatment of samples was highly correlated with coal C concentration calculated by radiocarbon activity (r{sup 2} = 0.95, P < 0.01). Therefore, both radiocarbon activity and chemi-thermal method were effective in estimating coal carbon concentration in reclaimed minesoils of southeast Ohio. Overall, both coal-C and recent OC fraction exhibited high spatial and depth variation, suggesting

  14. Distinct temperature sensitivity of soil carbon decomposition in forest organic layer and mineral soil.

    Science.gov (United States)

    Xu, Wenhua; Li, Wei; Jiang, Ping; Wang, Hui; Bai, Edith

    2014-10-01

    The roles of substrate availability and quality in determining temperature sensitivity (Q10) of soil carbon (C) decomposition are still unclear, which limits our ability to predict how soil C storage and cycling would respond to climate change. Here we determined Q10 in surface organic layer and subsurface mineral soil along an elevation gradient in a temperate forest ecosystem. Q10 was calculated by comparing the times required to respire a given amount of soil C at 15 and 25°C in a 350-day incubation. Results indicated that Q10 of the organic layer was 0.22-0.71 (absolute difference) higher than Q10 of the mineral soil. Q10 in both the organic layer (2.5-3.4) and the mineral soil (2.1-2.8) increased with decreasing substrate quality during the incubation. This enhancement of Q10 over incubation time in both layers suggested that Q10 of more labile C was lower than that of more recalcitrant C, consistent with the Arrhenius kinetics. No clear trend of Q10 was found along the elevation gradient. Because the soil organic C pool of the organic layer in temperate forests is large, its higher temperature sensitivity highlights its importance in C cycling under global warming.

  15. Soil carbon stabilization and turnover at alley-cropping systems, Eastern Germany

    Science.gov (United States)

    Medinski, T.; Freese, D.

    2012-04-01

    Alley-cropping system is seen as a viable land-use practice for mitigation of greenhouse gas CO2, energy-wood production and soil carbon sequestration. The extent to which carbon is stored in soil varies between ecosystems, and depends on tree species, soil types and on the extent of physical protection of carbon within soil aggregates. This study investigates soil carbon sequestration at alley-cropping systems presented by alleys of fast growing tree species (black locust and poplar) and maize, in Brandenburg, Eastern Germany. Carbon accumulation and turnover are assessed by measuring carbon fractions differing in decomposition rates. For this purpose soil samples were fractionated into labile and recalcitrant soil-size fractions by wet-sieving: macro (>250 µm), micro (53-250 µm) and clay + silt (<53 µm), followed by determination of organic carbon and nitrogen by gas-chromatography. Soil samples were also analysed for the total C&N content, cold-water extractable OC, and microbial C. Litter decomposition was evaluated by litter bags experiment. Soil CO2 flux was measured by LiCor automated device LI-8100A. No differences for the total and stable (clay+silt, <53 µm) carbon fraction were observed between treatment. While cold water-extractable carbon was significantly higher at maize alley compared to black locust alley. This may indicate faster turnover of organic matter at maize alley due to tillage, which influenced greater incorporation of plant residues into the soil, greater soil respiration and microbial activity.

  16. The influence of clay-to-carbon ratio on soil physical properties in a humid sandy loam soil with contrasting tillage and residue management

    DEFF Research Database (Denmark)

    Getahun, Gizachew Tarekegn; Munkholm, Lars Juhl; Schjønning, Per

    2016-01-01

    Tillage and residue management influence soil organic carbon (SOC) and lead to changes in soil physical behav-iour and functioning. We examined the effect of the clay-to-carbon ratio on soil physical properties in a humid sandy loam soil with contrasting tillage and residue management. Soil was sa...

  17. Selective extraction methods for aluminium, iron and organic carbon from montane volcanic ash soils

    NARCIS (Netherlands)

    Jansen, B.; Tonneijck, F.H.; Verstraten, J.M.

    2011-01-01

    Montane volcanic ash soils contain disproportionate amounts of soil organic carbon and thereby play an often underestimated role in the global carbon cycle. Given the central role of Al and Fe in stabilizing organic matter in volcanic ash soils, we assessed various extraction methods of Al, Fe, and

  18. The effects of permafrost thaw on soil hydrologic, thermal, and carbon dynamics in an Alaskan peatland

    Science.gov (United States)

    Jonathan A. O' Donnell; M.Torre Jorgenson; Jennifer W. Harden; A.David McGuire; Mikhail Z. Kanevskiy; Kimberly P. Wickland

    2012-01-01

    Recent warming at high-latitudes has accelerated permafrost thaw in northern peatlands, and thaw can have profound effects on local hydrology and ecosystem carbon balance. To assess the impact of permafrost thaw on soil organic carbon (OC) dynamics, we measured soil hydrologic and thermal dynamics and soil OC stocks across a collapse-scar bog chronosequence in interior...

  19. Soil carbon dioxide (CO 2 ) efflux of two shrubs in response to plant ...

    African Journals Online (AJOL)

    Although plant density should affect soil carbon dioxide (CO2) efflux and carbon cycling in semi-arid regions, the effects of plant density on soil CO2 efflux are not well known. This study was performed to investigate the responses of soil CO2 efflux of two dominant shrubs (Caragana korshinkii and Salix psammophila) to ...

  20. Projected changes in mineral soil carbon of European croplands and grasslands, 1990-2080

    NARCIS (Netherlands)

    Smith, J.; Smith, P.; Wattenbach, M.; Zaehle, S.; Hiederer, R.; Jones, R.J.A.; Montanarella, L.; Rounsevell, M.D.A.; Reginster, I.; Ewert, F.

    2005-01-01

    We present the most comprehensive pan-European assessment of future changes in cropland and grassland soil organic carbon (SOC) stocks to date, using a dedicated process-based SOC model and state-of-the-art databases of soil, climate change, land-use change and technology change. Soil carbon change

  1. Total organic carbon in aggregates as a soil recovery indicator

    Science.gov (United States)

    Luciene Maltoni, Katia; Rodrigues Cassiolato, Ana Maria; Amorim Faria, Glaucia; Dubbin, William

    2015-04-01

    The soil aggregation promotes physical protection of organic matter, preservation of which is crucial to improve soil structure, fertility and ensure the agro-ecosystems sustainability. The no-tillage cultivation system has been considered as one of the strategies to increase total soil organic carbono (TOC) contents and soil aggregation, both are closely related and influenced by soil management systems. The aim of this study was to evaluate the distribution of soil aggregates and the total organic carbon inside aggregates, with regard to soil recovery, under 3 different soil management systems, i.e. 10 and 20 years of no-tillage cultivation as compared with soil under natural vegetation (Cerrado). Undisturbed soils (0-5; 5-10; and 10-20 cm depth) were collected from Brazil, Central Region. The soils, Oxisols from Cerrado, were collected from a field under Natural Vegetation-Cerrado (NV), and from fields that were under conventional tillage since 1970s, and 10 and 20 years ago were changed to no-tillage cultivation system (NT-10; NT-20 respectively). The undisturbed samples were sieved (4mm) and the aggregates retained were further fractionated by wet sieving through five sieves (2000, 1000, 500, 250, and 50 μm) with the aggregates distribution expressed as percentage retained by each sieve. The TOC was determined, for each aggregate size, by combustion (Thermo-Finnigan). A predominance of aggregates >2000 μm was observed under NV treatment (92, 91, 82 %), NT-10 (64, 73, 61 %), and NT-20 (71, 79, 63 %) for all three depths (0-5; 5-10; 10-20 cm). In addition greater quantities of aggregates in sizes 1000, 500, 250 and 50 μm under NT-10 and NT-20 treatments, explain the lower aggregate stability under these treatments compared to the soil under NV. The organic C concentration for NV in aggregates >2000 μm was 24,4; 14,2; 8,7 mg/g for each depth (0-5; 5-10; 10-20 cm, respectively), higher than in aggregates sized 250-50 μm (7,2; 5,5; 4,4 mg/g) for all depths

  2. Modelling soil carbon flows and stocks following a carbon balance approach at regional scale for the EU-27

    Science.gov (United States)

    Lesschen, Jan Peter; Sikirica, Natasa; Bonten, Luc; Dibari, Camilla; Sanchez, Berta; Kuikman, Peter

    2014-05-01

    Soil Organic Carbon (SOC) is a key parameter to many soil functions and services. SOC is essential to support water retention and nutrient buffering and mineralization in the soil as well as to enhance soil biodiversity. Consequently, loss of SOC or low SOC levels might threaten soil productivity or even lead to a collapse of a farming system. Identification of areas in Europe with critically low SOC levels or with a negative carbon balance is a challenge in order to apply the appropriate strategies to restore these areas or prevent further SOC losses. The objective of this study is to assess current soil carbon flows and stocks at a regional scale; we follow a carbon balance approach which we developed within the MITERRA-Europe model. MITERRA-Europe is an environmental impact assessment model and calculates nitrogen and greenhouse emission on a deterministic and annual basis using emission and leaching factors at regional level (NUTS2, comparable to province level) in the EU27. The model already contained a soil carbon module based on the IPCC stock change approach. Within the EU FP7 SmartSoil project we developed a SOC balance approach, for which we quantified the input of carbon (manure, crop residues, other organic inputs) and the losses of carbon (decomposition, leaching and erosion). The calculations rules from the Roth-C model were used to estimate SOC decomposition. For the actual soil carbon stocks we used the data from the LUCAS soil sample survey. LUCAS collected soil samples in 2009 at about 22000 locations across the EU, which were analysed for a range of soil properties. Land management practices are accounted for, based on data from the EU wide Survey on Agricultural Production Methods in the 2010 Farm Structure Survey. The survey comprises data on the application of soil tillage, soil cover, crop rotation and irrigation. Based on the simulated soil carbon balance and the actual carbon stocks from LUCAS we now can identify regions within the EU that

  3. [Effects of nitrogen application and winter green manure on soil active organic carbon and the soil carbon pool management index].

    Science.gov (United States)

    Yang, Bin-Juan; Huang, Guo-Qin; Lan, Yan; Chen, Hong-Jun; Wang, Shu-Bin

    2014-10-01

    Based on a cropping system of "winter green manure-double rice", the 4 x 4 two-factor test was used to study the effects of different nitrogen (N) application levels and winter green manure application on soil active organic carbon (AOC) and the C pool management index. The aim was to explore the ecological effects of winter green manure on soil improvement and determine the appropriate application levels of N fertilizer and winter green manure for improved rice yield. Results were as follows: 1) Compared with the control, the SOC and AOC contents increased by 22.2% and 26.7%, respectively, under the green manure only treatment, but the SOC contents decreased by 0.6%-3.4% under the single N fertilizer treatment. Compared with the control, the soil C pool management index increased by 24.55 and 15.17 under the green manure only and green manure plus N fertilizer treatments, respectively, and reduced by 2.59 under the single N fertilizer treatment. Compared with no fertilization, the average microbial biomass carbon (MBC) increased by 54.0%, 95.2% and 14.3% under the green manure, green manure plus N fertilizer and single N fertilizer treatments, respectively. 2) The soil AOC content was significantly positively correlated with the C pool management index (P management index, and the correlation coefficient was significantly greater than that with the total organic C. These results suggested that application of winter green manure at proper rates with inorganic fertilizer could increase SOC contents and the soil C pool management index, improve soil quality and fertility.

  4. Agricultural management explains historic changes in regional soil carbon stocks

    Science.gov (United States)

    van Wesemael, Bas; Paustian, Keith; Meersmans, Jeroen; Goidts, Esther; Barancikova, Gabriela; Easter, Mark

    2010-01-01

    Agriculture is considered to be among the economic sectors having the greatest greenhouse gas mitigation potential, largely via soil organic carbon (SOC) sequestration. However, it remains a challenge to accurately quantify SOC stock changes at regional to national scales. SOC stock changes resulting from SOC inventory systems are only available for a few countries and the trends vary widely between studies. Process-based models can provide insight in the drivers of SOC changes, but accurate input data are currently not available at these spatial scales. Here we use measurements from a soil inventory dating from the 1960s and resampled in 2006 covering the major soil types and agricultural regions in Belgium together with region-specific land use and management data and a process-based model. The largest decreases in SOC stocks occurred in poorly drained grassland soils (clays and floodplain soils), consistent with drainage improvements since 1960. Large increases in SOC in well drained grassland soils appear to be a legacy effect of widespread conversion of cropland to grassland before 1960. SOC in cropland increased only in sandy lowland soils, driven by increasing manure additions. Modeled land use and management impacts accounted for more than 70% of the variation in observed SOC changes, and no bias could be demonstrated. There was no significant effect of climate trends since 1960 on observed SOC changes. SOC monitoring networks are being established in many countries. Our results demonstrate that detailed and long-term land management data are crucial to explain the observed SOC changes for such networks. PMID:20679194

  5. Agricultural management explains historic changes in regional soil carbon stocks.

    Science.gov (United States)

    van Wesemael, Bas; Paustian, Keith; Meersmans, Jeroen; Goidts, Esther; Barancikova, Gabriela; Easter, Mark

    2010-08-17

    Agriculture is considered to be among the economic sectors having the greatest greenhouse gas mitigation potential, largely via soil organic carbon (SOC) sequestration. However, it remains a challenge to accurately quantify SOC stock changes at regional to national scales. SOC stock changes resulting from SOC inventory systems are only available for a few countries and the trends vary widely between studies. Process-based models can provide insight in the drivers of SOC changes, but accurate input data are currently not available at these spatial scales. Here we use measurements from a soil inventory dating from the 1960s and resampled in 2006 covering the major soil types and agricultural regions in Belgium together with region-specific land use and management data and a process-based model. The largest decreases in SOC stocks occurred in poorly drained grassland soils (clays and floodplain soils), consistent with drainage improvements since 1960. Large increases in SOC in well drained grassland soils appear to be a legacy effect of widespread conversion of cropland to grassland before 1960. SOC in cropland increased only in sandy lowland soils, driven by increasing manure additions. Modeled land use and management impacts accounted for more than 70% of the variation in observed SOC changes, and no bias could be demonstrated. There was no significant effect of climate trends since 1960 on observed SOC changes. SOC monitoring networks are being established in many countries. Our results demonstrate that detailed and long-term land management data are crucial to explain the observed SOC changes for such networks.

  6. Stabilization of carbon in composts and biochars in relation to carbon sequestration and soil fertility.

    Science.gov (United States)

    Bolan, N S; Kunhikrishnan, A; Choppala, G K; Thangarajan, R; Chung, J W

    2012-05-01

    There have been increasing interests in the conversion of organic residues into biochars in order to reduce the rate of decomposition, thereby enhancing carbon (C) sequestration in soils. However energy is required to initiate the pyrolysis process during biochar production which can also lead to the release of greenhouse gasses. Alternative methods can be used to stabilize C in composts and other organic residues without impacting their quality. The objectives of this study include: (i) to compare the rate of decomposition among various organic amendments and (ii) to examine the effect of clay materials on the stabilization of C in organic amendments. The decomposition of a number of organic amendments (composts and biochars) was examined by monitoring the release of carbon-dioxide using respiration experiments. The results indicated that the rate of decomposition as measured by half life (t(1/2)) varied between the organic amendments and was higher in sandy soil than in clay soil. The half life value ranged from 139 days in the sandy soil and 187 days in the clay soil for poultry manure compost to 9989 days for green waste biochar. Addition of clay materials to compost decreased the rate of decomposition, thereby increasing the stabilization of C. The half life value for poultry manure compost increased from 139 days to 620, 806 and 474 days with the addition of goethite, gibbsite and allophane, respectively. The increase in the stabilization of C with the addition of clay materials may be attributed to the immobilization of C, thereby preventing it from microbial decomposition. Stabilization of C in compost using clay materials did not impact negatively the value of composts in improving soil quality as measured by potentially mineralizable nitrogen and microbial biomass carbon in soil. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. 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.

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

    Science.gov (United States)

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

    2014-12-01

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

  9. Carbon allocation and carbon isotope fluxes in the plant-soil-atmosphere continuum: a review

    Science.gov (United States)

    Brüggemann, N.; Gessler, A.; Kayler, Z.; Keel, S. G.; Badeck, F.; Barthel, M.; Boeckx, P.; Buchmann, N.; Brugnoli, E.; Esperschütz, J.; Gavrichkova, O.; Ghashghaie, J.; Gomez-Casanovas, N.; Keitel, C.; Knohl, A.; Kuptz, D.; Palacio, S.; Salmon, Y.; Uchida, Y.; Bahn, M.

    2011-11-01

    The terrestrial carbon (C) cycle has received increasing interest over the past few decades, however, there is still a lack of understanding of the fate of newly assimilated C allocated within plants and to the soil, stored within ecosystems and lost to the atmosphere. Stable carbon isotope studies can give novel insights into these issues. In this review we provide an overview of an emerging picture of plant-soil-atmosphere C fluxes, as based on C isotope studies, and identify processes determining related C isotope signatures. The first part of the review focuses on isotopic fractionation processes within plants during and after photosynthesis. The second major part elaborates on plant-internal and plant-rhizosphere C allocation patterns at different time scales (diel, seasonal, interannual), including the speed of C transfer and time lags in the coupling of assimilation and respiration, as well as the magnitude and controls of plant-soil C allocation and respiratory fluxes. Plant responses to changing environmental conditions, the functional relationship between the physiological and phenological status of plants and C transfer, and interactions between C, water and nutrient dynamics are discussed. The role of the C counterflow from the rhizosphere to the aboveground parts of the plants, e.g. via CO2 dissolved in the xylem water or as xylem-transported sugars, is highlighted. The third part is centered around belowground C turnover, focusing especially on above- and belowground litter inputs, soil organic matter formation and turnover, production and loss of dissolved organic C, soil respiration and CO2 fixation by soil microbes. Furthermore, plant controls on microbial communities and activity via exudates and litter production as well as microbial community effects on C mineralization are reviewed. A further part of the paper is dedicated to physical interactions between soil CO2 and the soil matrix, such as CO2 diffusion and dissolution processes within the

  10. Responses of soil carbon turnover rates to pyrogenic carbon additions to a forest soil of Sierra Nevada, California: effects of pyrolysis temperature and soil depth

    Science.gov (United States)

    Santos, F.; Bird, J. A.; Berhe, A. A.

    2017-12-01

    Pyrogenic organic carbon (PyC) is a heterogenous mixture of thermally altered residues, ranging from slightly charred plant biomass to soot. Despite its apparent stability in soils, PyC has been reported to either increase or decrease (priming effect, PE), or have no effect on the mineralization rates of native soil organic matter (SOM), highlighting our limited knowledge on the mechanisms driving PyC-induced PE. Little is known about how PyC's pyrolysis temperature, and soil depth (surface versus subsurface) affect the direction of PE. To address this gap knowledge, we conducted from a 1-year laboratory incubation study aimed to investigate the interactive effects of pyrolysis temperature and soil depth on the mineralization rates of native SOM in fine-loamy, temperate forest soil that received additions of dual-labeled 13C and 15N jack pine pyrogenic organic matter produced at 300oC (PyC300) and 450oC (PyC450). Soil and PyC mixture were incubated in surface (0-10 cm) and subsurface (50-70 cm) forest soils in the dark at 55% soil field capacity and 25oC. Losses of native SOM as 13CO2 were measured periodically from the 13C-labeled PyC, and native (unlabeled) SOM during the incubation study using a Thermo Scientific GasBench interfaced to a Delta V Plus isotope ratio mass spectrometer. In surface soils, the addition of PyC300 decreased the turnover rates of native C relative to control treatments, whereas PyC400 had no effect on native C turnover rates. In subsurface soils, neither PyC300 nor PyC400 additions affected native C turnover rates. Our preliminary findings suggest that pyrolysis temperature is an important factor driving the persistence of soil C in Sierra Nevada forest soils.

  11. Implications of Different Worldviews to Assess Soil Organic Carbon Change

    Science.gov (United States)

    Grunwald, S.

    2012-04-01

    Profound shifts have occurred over the last three centuries in which human actions have become the main driver to global environmental change. In this new epoch, the Anthropocene, human-driven changes such as climate and land use change, are pushing the Earth system well outside of its normal operating range causing severe and abrupt environmental change. Changes in land use management and land cover are intricately linked to the carbon cycle, but our knowledge on its spatially and temporally explicit impact on carbon dynamics across different scales is still poorly understood. To elucidate on the magnitude of change in soil organic carbon (SOC) due to human-induced stressors different philosophical worldviews may be considered including (i) empiricism - direct measurements of properties and processes at micro, site-specific or field scales; (ii) metaphysics and ontology - conceptual models to assess soil change (e.g., STEP-AWBH); (iii) epistemology - indirect approaches (e.g., meta-analysis or spectral informed prediction models); (iv) reductionism - e.g., carbon flux measurements; (iv) determinism - mechanistic simulation models and biogeochemical investigations (e.g., Century or DNDC); (v) holism - national or global soil databases and aggregate maps; or (vi) integral - fusing individual, social, economic, cultural and empirical perspectives. The strengths and limitations of each of these philosophical approaches are demonstrated using case examples from Florida and U.S.A. The sensitivity to assess SOC change and uncertainty, backcasting and forecasting ability, scaling potential across space and time domains, and limitations and constraints of different worldviews are discussed.

  12. Soil Organic Carbon Redistribution by Water Erosion - The Role of CO2 Emissions for the Carbon Budget

    NARCIS (Netherlands)

    Wang, X.; Cammeraat, E.L.H.; Romeijn, P.; Kalbitz, K.

    2014-01-01

    A better process understanding of how water erosion influences the redistribution of soil organic carbon (SOC) is sorely needed to unravel the role of soil erosion for the carbon (C) budget from local to global scales. The main objective of this study was to determine SOC redistribution and the

  13. Assessment of wintertime atmospheric pollutants in an urban area of Kansai, Japan

    Science.gov (United States)

    Ma, Chang-Jin; Oki, Yoshishige; Tohno, Susumu; Kasahara, Mikio

    An intensive measurement of particulate matter and gaseous materials was made to assess the characteristics of wintertime atmospheric pollutants in an urban area of Kansai, Japan. Sampling was performed by a combination of filter pack sampler and low-pressure Andersen impactor (LPAI). Particle-induced X-ray Emission (PIXE) and Thermal/Optical Reflectance (TOR ®) methods were employed in analyzing element and carbon, respectively. The concentrations of SO 2, NO x, and PM 2.5 monitored during our intensive measurement show a strong time serial variation. PM 2.5 levels are higher in the daytime with an average level of 21.3 μg m -3. Most of the peaks for NO x were regularly found in the morning throughout the campaign duration. The number concentration of particles larger than 0.3 μm appears dominated by the ultrafine particles ranged between 0.3 and 0.5 μm. The size distribution of elemental concentration as a function of water solubility was investigated. Organic carbon (OC) concentration shows the strong size distribution with the main peak formed in a range of 0.29-0.67 μm, while elemental carbon (EC) is principally enriched in a range of 0.12-0.29 μm ultra fine fraction. TC (OC+EC) fraction accounts for 42.5% and 26.2% of the mass concentration in fine particle fraction (1.17 μm), respectively. The simulated backward aerosol dispersion with the surface wind roses for three events of high PM 2.5 mass concentration indicates that aerosol dispersions might be originated from the emission sources of Osaka and Shiga. Also the possibility of long-range transportation of fine particulate matter from the domestic areas of Japan, Taiwan, and Pacific Ocean was still raised. The result of factor analysis indicates that automobile exhaust, fossil fuel combustion, refuse incineration, iron industry, and soil originated particles contribute the major portion of PM 2.5 in our sampling area.

  14. Long-term rice cultivation stabilizes soil organic carbon and promotes soil microbial activity in a salt marsh derived soil chronosequence

    Science.gov (United States)

    Wang, Ping; Liu, Yalong; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Joseph, Stephen; Pan, Genxing

    2015-01-01

    Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist. PMID:26503629

  15. Long-term rice cultivation stabilizes soil organic carbon and promotes soil microbial activity in a salt marsh derived soil chronosequence.

    Science.gov (United States)

    Wang, Ping; Liu, Yalong; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Joseph, Stephen; Pan, Genxing

    2015-10-27

    Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist.

  16. A simple, gravimetric method to quantify inorganic carbon in calcareous soils

    Science.gov (United States)

    Total carbon (TC) in calcareous soils has two components: inorganic carbon (IC) as calcite and or dolomite and organic carbon (OC) in the soil organic matter. The IC must be measured and subtracted from TC to obtain OC. Our objective was to develop a simple gravimetric technique to quantify IC. Th...

  17. Quantitative assessment of the differential impacts of arbuscular and ectomycorrhiza on soil carbon cycling

    NARCIS (Netherlands)

    Soudzilovskaia, Nadejda A.; van der Heijden, Marcel G A|info:eu-repo/dai/nl/240923901; Cornelissen, Johannes H C; Makarov, Mikhail I.; Onipchenko, Vladimir G.; Maslov, Mikhail N.; Akhmetzhanova, Asem A.; van Bodegom, Peter M.

    2015-01-01

    A significant fraction of carbon stored in the Earth's soil moves through arbuscular mycorrhiza (AM) and ectomycorrhiza (EM). The impacts of AM and EM on the soil carbon budget are poorly understood. We propose a method to quantify the mycorrhizal contribution to carbon cycling, explicitly

  18. Viral impacts on microbial carbon cycling in thawing permafrost soils

    Science.gov (United States)

    Trubl, G. G.; Roux, S.; Bolduc, B.; Jang, H. B.; Emerson, J. B.; Solonenko, N.; Li, F.; Solden, L. M.; Vik, D. R.; Wrighton, K. C.; Saleska, S. R.; Sullivan, M. B.; Rich, V. I.

    2017-12-01

    Permafrost contains 30-50% of global soil carbon (C) and is rapidly thawing. While the fate of this C is unknown, it will be shaped in part by microbes and their associated viruses, which modulate host activities via mortality and metabolic control. To date, viral research in soils has been outpaced by that in aquatic environments, due to the technical challenges of accessing viruses as well as the dramatic physicochemical heterogeneity in soils. Here, we describe advances in soil viromics from our research on permafrost-associated soils, and their implications for associated terrestrial C cycling. First, we optimized viral resuspension-DNA extraction methods for a range of soil types. Second, we applied cutting-edge viral-specific informatics methods to recover viral populations, define their gene content, connect them to potential hosts, and analyze their relationships to environmental parameters. A total of 781 viral populations were recovered from size-fractionated virus samples of three soils along a permafrost thaw gradient. Ecological analyses revealed endemism as recovered viral populations were largely unique to each habitat and unlike those in aquatic communities. Genome- and network-based classification assigned these viruses into 226 viral clusters (VCs; genus-level taxonomy), 55% of which were novel. This increases the number of VCs by a third and triples the number of soil viral populations in the RefSeq database (currently contains 256 VCs and 316 soil viral populations). Genomic analyses revealed 85% of the genes were functionally unknown, though 5% of the annotatable genes contained C-related auxiliary metabolic genes (AMGs; e.g. glycoside hydrolases). Using sequence-based features and microbial population genomes, we were able to in silico predict hosts for 30% of the viral populations. The identified hosts spanned 3 phyla and 6 genera but suggested these viruses have species-specific host ranges as >80% of hosts for a given virus were in the same

  19. Easily degradable carbon - an indicator of microbial hotspots and soil degradation

    Science.gov (United States)

    Wolińska, Agnieszka; Banach, Artur; Szafranek-Nakonieczna, Anna; Stępniewska, Zofia; Błaszczyk, Mieczysław

    2018-01-01

    The effect of arable soil was quantified against non-cultivated soil on easily degradable carbon and other selected microbiological factors, i.e. soil microbial biomass, respiration activity, and dehydrogenase activity. The intent was to ascertain whether easily degradable carbo can be useful as a sensitive indicator of both soil biological degradation and microbial hot-spots indication. As a result, it was found that soil respiration activity was significantly higher (p soils. Dehydrogenase activity was significantly lower in the arable soil (down to 35-40% of the control values, p soil type. The microbial biomass was also significantly higher at the non-cultivated soil (512-2807 vs. 416-1429 µg g-1 d.m., p soil and 497-877 mg kg-1 arable soil (p soil properties by significantly reducing the levels of the studied parameters in relation to the control soils. The significant correlations of easily degradable carbon-respiration activity (ρ = 0.77*), easily degradable carbon-dehydrogenase activity (ρ = 0.42*), and easily degradable carbon-microbial biomass (ρ = 0.53*) reveal that easily degradable carbon is a novel, suitable factor indicative of soil biological degradation. It, therefore, could be used for evaluating the degree of soil degradation and for choosing a proper management procedure.

  20. How energetic and environmental constraints of microorganisms determine the carbon turnover in soils

    Science.gov (United States)

    Don, A.; Rödenbeck, C.; Gleixner, G.

    2012-04-01

    Microorganisms are the main catalysts driving carbon fluxes from soils. Traditional concepts of soil carbon stabilization failed to account for environmental and energy constraints of microorganisms. The distribution and density of organic carbon in the soil profile maybe a key factor determining the carbon stability and carbon flux. Decomposition is a two-step process following the Michaelis Menten kinetics: In a first step enzyme and substrate form a joint complex and then the decomposition reaction is catalyzed. Thus, biological decomposition relies on the encounter of substrate and the degradation catalyst, the microorganisms. Lower substrate concentration decreases the likelihood of an enzyme to hit a substrate molecule, to form an enzyme-substrate complex, and thus to catalyze the reaction. However, it was unproofen if this concept can be appliued to soils also. A long-term lab experiment revealed that the soil carbon turnover decreased with increasing carbon dilution due to mixture with soil minerals. The ability of microorganisms to move towards substrate in soils seems to be limited. To elucidate the effect of concentration-controlled carbon turnover, we devised the simple simulation model SCAMP based on the two-step kinetic with microorganism and carbon particles been simulated explicitly. The SCAMP model was able to simulate soil carbon profiles and age profiles in a realistic manner. The only carbon stabilization mechanism implemented in the model is the distribution of microorganisms and carbon particles in the soil and thus the availability of carbon for microorganism, which is especially important for subsoil carbon dynamics. The experiments and the model help to explain why large fractions of soil carbon have been stabilized for millennia and decoupled from the global carbon cycle.

  1. The Evolution of Black Carbon Physicochemical Properties in Soils

    Science.gov (United States)

    Muñiz, Y.; Pyle, L. A.; Masiello, C. A.

    2016-12-01

    Black Carbon (BC) is a unique product of the incomplete combustion of biomass that occurs during wildfires. BC is a partially combusted solid residue of plant tissue that is highly porous, a source of soil organic carbon, and degrades more slowly than other forms of organic matter. A recent study by Westerling et al. 2006 showed that regional changes in climate led to increased wildfire activity over recent decades. One implication of this is that as the climate changes, increasing wildfire rates may increase production of BC. We analyzed how the physical and chemical properties of BC particles change over time in order to assess the stability of BC in soils. BC used in this study came from soils collected in Silas Little Experimental Forest (SLEF) which is a US Forest Service Site in the New Jersey Pine Barrens. This area has historical and geographical records on occurrences of fire events beginning in 1935. This allows us to simulate an almost 85 year study by looking at a range of BC particles of very different ages spanning the years between 1935 and 2015. BC particles from five different locations within SLEF were selected to represent the years 1930, 1963, 1995, and 2015. We used pycnometry to measure skeletal density where volume of pores is excluded and envelope density where volume of pores is included. Density of BC particles is important because it impacts BC mobility and interaction with soil and water which can affect whether BC will get stored in soils or be weathered away. We also used an elemental analyzer to measure the weight percent of carbon, hydrogen, and nitrogen of the BC particles to identify relative mineral and organic contributions. Pycnometry results revealed an overall increase in the skeletal density of aged BC particles from 1.64 to 1.70 g/cm3, and that BC particles from the O horizon had a lower skeletal density (1.60-1.71 g/cm3) than those from the A horizon (1.68- 1.77 g/cm3). Elemental analysis revealed a weight percent increase

  2. Soil Organic Carbon Fractions and Stocks Respond to Restoration Measures in Degraded Lands by Water Erosion

    Science.gov (United States)

    Nie, Xiaodong; Li, Zhongwu; Huang, Jinquan; Huang, Bin; Xiao, Haibing; Zeng, Guangming

    2017-05-01

    Assessing the degree to which degraded soils can be recovered is essential for evaluating the effects of adopted restoration measures. The objective of this study was to determine the restoration of soil organic carbon under the impact of terracing and reforestation. A small watershed with four typical restored plots (terracing and reforestation (four different local plants)) and two reference plots (slope land with natural forest (carbon-depleted) and abandoned depositional land (carbon-enriched)) in subtropical China was studied. The results showed that soil organic carbon, dissolved organic carbon and microbial biomass carbon concentrations in the surface soil (10 cm) of restored lands were close to that in abandoned depositional land and higher than that in natural forest land. There was no significant difference in soil organic carbon content among different topographic positions of the restored lands. Furthermore, the soil organic carbon stocks in the upper 60 cm soils of restored lands, which were varied between 50.08 and 62.21 Mg C ha-1, were higher than 45.90 Mg C ha-1 in natural forest land. Our results indicated that the terracing and reforestation could greatly increase carbon sequestration and accumulation and decrease carbon loss induced by water erosion. And the combination measures can accelerate the restoration of degraded soils when compared to natural forest only. Forest species almost have no impact on the total amount of soil organic carbon during restoration processes, but can significantly influence the activity and stability of soil organic carbon. Combination measures which can provide suitable topography and continuous soil organic carbon supply could be considered in treating degraded soils caused by water erosion.

  3. Soil Organic Carbon Fractions and Stocks Respond to Restoration Measures in Degraded Lands by Water Erosion.

    Science.gov (United States)

    Nie, Xiaodong; Li, Zhongwu; Huang, Jinquan; Huang, Bin; Xiao, Haibing; Zeng, Guangming

    2017-05-01

    Assessing the degree to which degraded soils can be recovered is essential for evaluating the effects of adopted restoration measures. The objective of this study was to determine the restoration of soil organic carbon under the impact of terracing and reforestation. A small watershed with four typical restored plots (terracing and reforestation (four different local plants)) and two reference plots (slope land with natural forest (carbon-depleted) and abandoned depositional land (carbon-enriched)) in subtropical China was studied. The results showed that soil organic carbon, dissolved organic carbon and microbial biomass carbon concentrations in the surface soil (10 cm) of restored lands were close to that in abandoned depositional land and higher than that in natural forest land. There was no significant difference in soil organic carbon content among different topographic positions of the restored lands. Furthermore, the soil organic carbon stocks in the upper 60 cm soils of restored lands, which were varied between 50.08 and 62.21 Mg C ha -1 , were higher than 45.90 Mg C ha -1 in natural forest land. Our results indicated that the terracing and reforestation could greatly increase carbon sequestration and accumulation and decrease carbon loss induced by water erosion. And the combination measures can accelerate the restoration of degraded soils when compared to natural forest only. Forest species almost have no impact on the total amount of soil organic carbon during restoration processes, but can significantly influence the activity and stability of soil organic carbon. Combination measures which can provide suitable topography and continuous soil organic carbon supply could be considered in treating degraded soils caused by water erosion.

  4. Modeling Soil Organic Carbon Turnover in Four Temperate Forests Based on Radiocarbon Measurements of Heterotrophic Respiration and Soil Organic Carbon

    Science.gov (United States)

    Ahrens, B.; Borken, W.; Muhr, J.; Schrumpf, M.; Savage, K. E.; Wutzler, T.; Trumbore, S.; Reichstein, M.

    2011-12-01

    Soils of temperate forests store significant amounts of soil organic matter and are considered to be net sinks of atmospheric CO2. Soil organic carbon (SOC) dynamics have been studied using the Δ14C signature of bulk SOC or different SOC fractions as observational constraints in SOC models. Further, the Δ14C signature of CO2 evolved during the incubation of soil and roots has been widely used together with Δ14C of total soil respiration to partition soil respiration into heterotrophic respiration (Rh) and root respiration. However, these data have rarely been used together as observational constraints to determine SOC turnover times. Here, we present a multiple constraints approach, where we used SOC stock and its Δ14C signature, and heterotrophic respiration and its Δ14C signature to estimate SOC turnover times of a simple serial two-pool model via Bayesian optimization. We used data from four temperate forest ecosystems in Germany and the USA with different disturbance and management histories from selective logging to afforestation in the late 19th and early 20th century. The Δ14C signature of the atmosphere with its prominent bomb peak was used as a proxy for the Δ14C signature of aboveground and belowground litterfall. The Δ14C signature of litterfall was lagged behind the atmospheric signal to account for the period between photosynthetic fixation of carbon and its addition to SOC pools. We showed that the combined use of Δ14C measurements of Rh and SOC stocks helped to better constrain turnover times of the fast pool (primarily by Δ14C of Rh) and the slow pool (primarily by Δ14C of SOC). In particular, by introducing two additional parameters that describe the deviation from steady state of the fast and slow cycling pool for both SOC and SO14C, we were able to demonstrate that we cannot maintain the often used steady-state assumption of SOC models in general. Furthermore, a new transport version of our model, including SOC transport via

  5. Organic carbon accumulation capability of two typical tidal wetland soils in Chongming Dongtan, China.

    Science.gov (United States)

    Zhang, Shiping; Wang, Lei; Hu, Jiajun; Zhang, Wenquan; Fu, Xiaohua; Le, Yiquan; Jin, Fangming

    2011-01-01

    We measured organic carbon input and content of soil in two wetland areas of Chongming Dongtan (Yangtze River Estuary) to evaluate variability in organic carbon accumulation capability in different wetland soils. Observed differences were investigated based on the microbial activity and environmental factors of the soil at the two sites. Results showed that the organic carbon content of wetland soil vegetated with Phragmites australis (site A) was markedly lower than that with P. australis and Spartina alterniflora (site B). Sites differences were due to higher microbial activity at site A, which led to higher soil respiration intensity and greater carbon outputs. This indicated that the capability of organic carbon accumulation of the site B soils was greater than at site A. In addition, petroleum pollution and soil salinity were different in the two wetland soils. After bio-remediation, the soil petroleum pollution at site B was reduced to a similar level of site A. However, the culturable microbial biomass and enzyme activity in the remediated soils were also lower than at site A. These results indicated that greater petroleum pollution at site B did not markedly inhibit soil microbial activity. Therefore, differences in vegetation type and soil salinity were the primary factors responsible for the variation in microbial activity, organic carbon output and organic carbon accumulation capability between site A and site B.

  6. Elevated carbon dioxide does not offset loss of soil carbon from a corn-soybean agroecosystem

    International Nuclear Information System (INIS)

    Moran, Kelly K.; Jastrow, Julie D.

    2010-01-01

    The potential for storing additional C in U.S. Corn Belt soils - to offset rising atmospheric [CO 2 ] - is large. Long-term cultivation has depleted substantial soil organic matter (SOM) stocks that once existed in the region's native ecosystems. In central Illinois, free-air CO 2 enrichment technology was used to investigate the effects of elevated [CO 2 ] on SOM pools in a conservation tilled corn-soybean rotation. After 5 and 6 y of CO 2 enrichment, we investigated the distribution of C and N among soil fractions with varying ability to protect SOM from rapid decomposition. None of the isolated C or N pools, or bulk-soil C or N, was affected by CO 2 treatment. However, the site has lost soil C and N, largely from unprotected pools, regardless of CO 2 treatment since the experiment began. These findings suggest management practices have affected soil C and N stocks and dynamics more than the increased inputs from CO 2 -stimulated photosynthesis. - Soil carbon from microaggregate-protected and unprotected fractions decreased in a conservation tilled corn-soybean rotation despite increases in primary production from exposure to atmospheric CO 2 enrichment.

  7. Soil microbial community and its interaction with soil carbon and nitrogen dynamics following afforestation in central China.

    Science.gov (United States)

    Deng, Qi; Cheng, Xiaoli; Hui, Dafeng; Zhang, Qian; Li, Ming; Zhang, Quanfa

    2016-01-15

    Afforestation may alter soil microbial community structure and function, and further affect soil carbon (C) and nitrogen (N) dynamics. Here we investigated soil microbial carbon and nitrogen (MBC and MBN) and microbial community [e.g. bacteria (B), fungi (F)] derived from phospholipid fatty acids (PLFAs) analysis in afforested (implementing woodland and shrubland plantations) and adjacent croplands in central China. Relationships of microbial properties with biotic factors [litter, fine root, soil organic carbon (SOC), total nitrogen (TN) and inorganic N], abiotic factors (soil temperature, moisture and pH), and major biological processes [basal microbial respiration, microbial metabolic quotient (qCO2), net N mineralization and nitrification] were developed. Afforested soils had higher mean MBC, MBN and MBN:TN ratios than the croplands due to an increase in litter input, but had lower MBC:SOC ratio resulting from low-quality (higher C:N ratio) litter. Afforested soils also had higher F:B ratio, which was probably attributed to higher C:N ratios in litter and soil, and shifts of soil inorganic N forms, water, pH and disturbance. Alterations in soil microbial biomass and community structure following afforestation were associated with declines in basal microbial respiration, qCO2, net N mineralization and nitrification, which likely maintained higher soil carbon and nitrogen storage and stability. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Impact of shade and cocoa plant densities on soil organic carbon ...

    African Journals Online (AJOL)

    user

    Cropping systems have influence on the conservation of soil organic matter. Soil samples were taken from a long term experiment that was designed to study the impact of shade and cocoa plant densities on cocoa yields. The impact of the treatments on soil organic carbon sequestration rates and the gains or losses of soil ...

  9. Soil organic carbon quality in forested mineral wetlands at different mean annual temperature.

    Science.gov (United States)

    Cinzia Fissore; Christian P. Giardina; Randall K. Kolka; Carl C. Trettin

    2009-01-01

    Forested mineral soil wetlands (FMSW) store large stocks of soil organic carbon (SOC), but little is known on: (i) whether the quality of SOC stored in these soils (proportion of active versus more resistant SOC compounds) differs from SOC in upland soils; (ii) how the quality of SOC in FMSW varies with mean annual temperature (MAT); and (iii) whether SOC decomposition...

  10. [Humus composition and stable carbon isotope natural abundance in paddy soil under long-term fertilization].

    Science.gov (United States)

    Ma, Li; Yang, Lin-Zhang; Ci, En; Wang, Yan; Yin, Shi-Xue; Shen, Ming-Xing

    2008-09-01

    Soil samples were collected from an experimental paddy field with long-term (26 years) fertilization in Taihu Lake region of Jiangsu Province to study the effects of different fertilization on the organic carbon distribution and stable carbon isotope natural abundance (delta 13C) in the soil profile, and on the humus composition. The results showed that long-term fertilization increased the organic carbon content in top soil significantly, and there was a significantly negative exponential correlation between soil organic carbon content and soil depth (P organic carbon content in 10-30 cm soil layer under chemical fertilizations and in 20-40 cm soil layer under organic fertilizations was relatively stable. Soil delta 13C increased gradually with soil depth, its variation range being from -24% per thousand to -28 per thousand, and had a significantly negative linear correlation with soil organic carbon content (P soil layer, the delta 13C in treatments organic manure (M), M + NP, M + NPK, M + straw (R) + N, and R + N decreased significantly; while in 30-50 cm soil layer, the delta 13C in all organic fertilization treatments except R + N increased significantly. Tightly combined humus (humin) was the main humus composition in the soil, occupying 50% or more, and the rest were loosely and stably combined humus. Long-term fertilization increased the content of loosely combined humus and the ratio of humic acid (HA) to fulvic acid (FA).

  11. Hydrothermal Carbonization: a feasible solution to convert biomass to soil?

    Science.gov (United States)

    Tesch, Walter; Tesch, Petra; Pfeifer, Christoph

    2013-04-01

    The erosion of fertile soil is a severe problem arising right after peak oil (Myers 1996). That this issue is not only a problem of arid countries is shown by the fact that even the European Commission defined certain milestones to address the problem of soil erosion in Europe (European Commission 2011). The application of bio-char produced by torrefaction or pyrolysis for the remediation, revegetation and restoration of depleted soils started to gain momentum recently (Rillig 2010, Lehmann 2011, Beesley 2011). Hydrothermal carbonization (HTC) is a promising thermo-chemical process that can be applied to convert organic feedstock into fertile soil and water, two resources which are of high value in regions being vulnerable to erosion. The great advantage of HTC is that organic feedstock (e.g. organic waste) can be used without any special pretreatment (e.g. drying) and so far no restrictions have been found regarding the composition of the organic matter. By applying HTC the organic material is processed along a defined pathway in the Van Krevelen plot (Behrendt 2006). By stopping the process at an early stage a nutritious rich material can be obtained, which is known to be similar to terra preta. Considering that HTC-coal is rich in functional groups and can be derived from the process under "wet" conditions, it can be expected that it shall allow soil bacteria to settle more easily compared to the bio-char derived by torrefaction or pyrolysis. In addition, up to 10 tons process water per ton organic waste can be gained (Vorlop 2009). Thus, as organic waste, loss of fertile soil and water scarcity becomes a serious issue within the European Union, hydrothermal carbonization can provide a feasible solution to address these issues of our near future. The presentation reviews the different types of feedstock investigated for the HTC-Process so far and gives an overview on the current stage of development of this technology. References Beesley L., Moreno-Jiménez E

  12. Soil organic carbon of an intensively reclaimed region in China: Current status and carbon sequestration potential.

    Science.gov (United States)

    Deng, Xunfei; Zhan, Yu; Wang, Fei; Ma, Wanzhu; Ren, Zhouqiao; Chen, Xiaojia; Qin, Fangjin; Long, Wenli; Zhu, Zhenling; Lv, Xiaonan

    2016-09-15

    Land reclamation has been highly intensive in China, resulting in a large amount of soil organic carbon (SOC) loss to the atmosphere. Evaluating the factors which drive SOC dynamics and carbon sequestration potential in reclaimed land is critical for improving soil fertility and mitigating global warming. This study aims to determine the current status and factors important to the SOC density in a typical reclaimed land located in Eastern China, where land reclamation has been undergoing for centuries. A total of 4746 topsoil samples were collected from 2007 to 2010. The SOC density of the reclaimed land (3.18±0.05kgCm(-2); mean±standard error) is significantly lower than that of the adjacent non-reclaimed land (5.71±0.04kgCm(-2)) (pcarbon sequestration potential of the reclaimed lands may achieve a maximum of 5.80±1.81kgCO2m(-2) (mean±SD) when dryland is converted to flooded land with vegetable-rice cropping system and soil pH of ~5.9. Note that in some scenarios the methane emission substantially offsets the carbon sequestration potential, especially for continuous rice cropping system. With the optimal setting for carbon sequestration, it is estimated that the dryland reclaimed in the last 50years in China is able to sequester 0.12milliontons CO2 equivalent per year. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Impacts of twenty years of experimental warming on soil carbon, nitrogen, moisture and soil across alpine/subarctic tundra communities

    OpenAIRE

    M. Alatalo, Juha; K. Jägerbrand, Annika; Juhanson, Jaanis; Michelsen, Anders; Ľuptáčik, Peter

    2017-01-01

    High-altitude and alpine areas are predicted to experience rapid and substantial increases in future temperature, which may have serious impacts on soil carbon, nutrient and soil fauna. Here we report the impact of 20 years of experimental warming on soil properties and soil mites in three contrasting plant communities in alpine/subarctic Sweden. Long-term warming decreased juvenile oribatid mite density, but had no effect on adult oribatids density, total mite density, any major mite group o...

  14. Potential carbon emissions dominated by carbon dioxide from thawed permafrost soils

    Science.gov (United States)

    Schädel, Christina; Bader, Martin K.-F.; Schuur, Edward A.G.; Biasi, Christina; Bracho, Rosvel; Čapek, Petr; De Baets, Sarah; Diáková, Kateřina; Ernakovich, Jessica; Estop-Aragones, Cristian; Graham, David E.; Hartley, Iain P.; Iversen, Colleen M.; Kane, Evan S.; Knoblauch, Christian; Lupascu, Massimo; Martikainen, Pertti J.; Natali, Susan M.; Norby, Richard J.; O'Donnell, Jonathan A.; Roy Chowdhury, Taniya; Šantrůčková, Hana; Shaver, Gaius; Sloan, Victoria L.; Treat, Claire C.; Turetsky, Merritt R.; Waldrop, Mark P.; Wickland, Kimberly P.

    2016-01-01

    Increasing temperatures in northern high latitudes are causing permafrost to thaw, making large amounts of previously frozen organic matter vulnerable to microbial decomposition. Permafrost thaw also creates a fragmented landscape of drier and wetter soil conditions that determine the amount and form (carbon dioxide (CO2), or methane (CH4)) of carbon (C) released to the atmosphere. The rate and form of C release control the magnitude of the permafrost C feedback, so their relative contribution with a warming climate remains unclear. We quantified the effect of increasing temperature and changes from aerobic to anaerobic soil conditions using 25 soil incubation studies from the permafrost zone. Here we show, using two separate meta-analyses, that a 10 °C increase in incubation temperature increased C release by a factor of 2.0 (95% confidence interval (CI), 1.8 to 2.2). Under aerobic incubation conditions, soils released 3.4 (95% CI, 2.2 to 5.2) times more C than under anaerobic conditions. Even when accounting for the higher heat trapping capacity of CH4, soils released 2.3 (95% CI, 1.5 to 3.4) times more C under aerobic conditions. These results imply that permafrost ecosystems thawing under aerobic conditions and releasing CO2 will strengthen the permafrost C feedback more than waterlogged systems releasing CO2 and CH4 for a given amount of C.

  15. Soil nitrogen and carbon impacts of raising chickens on pasture

    Science.gov (United States)

    Ryals, R.; Leach, A.; Tang, J.; Hastings, M. G.; Galloway, J. N.

    2014-12-01

    Chicken is the most consumed meat in the US, and production continues to intensify rapidly around the world. Chicken manure from confined feeding operations is typically applied in its raw form to nearby croplands, resulting in hotspots of soil nitrous oxide (N2O) emissions. Pasture-raised chicken is an alternative to industrial production and is growing in popularity with rising consumer demand for more humanely raised protein sources. In this agricultural model, manure is deposited directly onto grassland soils where it is thought to increase pools of soil carbon and nitrogen. The fate of manure nitrogen from pasture-raised chicken production remains poorly understood. We conducted a controlled, replicated experiment on a permaculture farm in Charlottesville, Virginia (Timbercreek Organics) in which small chicken coops (10 ft x 12 ft) were moved daily in a pasture. We measured manure deposition rates, soil inorganic nitrogen pools, soil moisture, and soil N2O and CO2 emissions. Measurements were made for the 28-day pasture life of three separate flocks of chickens in the spring, summer, and fall. Each flock consisted of approximately 200-300 chickens occupying three to five coops (~65 chickens/coop). Measurements were also made in paired ungrazed control plots. Manure deposition rates were similar across flocks and averaged 1.5 kgdrywt ha-1 during the spring grazing event and 4.0 kgdrywt ha-1 during the summer and fall grazing events. Manure deposition was relatively constant over the four weeks pasture-lifetime of the chickens. Compared to control plots, grazed areas exhibited higher soil N2O and CO2 fluxes. The magnitude of these fluxes diminished significantly over the four-week span. Soil gas fluxes significantly increased following rainfall events. For a given rainfall event, higher fluxes were observed from transects that were grazed more recently. Soil gaseous reactive nitrogen losses were less in this pasture system compared to cultivated field amended

  16. Soil carbon distribution in Alaska in relation to soil-forming factors

    Science.gov (United States)

    Johnson, K.D.; Harden, J.; McGuire, A.D.; Bliss, N.B.; Bockheim, James G.; Clark, M.R.; Nettleton-Hollingsworth, T.; Jorgenson, M.T.; Kane, E.S.; Mack, M.; O'Donnell, J.; Ping, C.-L.; Schuur, E.A.G.; Turetsky, M.R.; Valentine, D.W.

    2011-01-01

    The direction and magnitude of soil organic carbon (SOC) changes in response to climate change remain unclear and depend on the spatial distribution of SOC across landscapes. Uncertainties regarding the fate of SOC are greater in high-latitude systems where data are sparse and the soils are affected by sub-zero temperatures. To address these issues in Alaska, a first-order assessment of data gaps and spatial distributions of SOC was conducted from a recently compiled soil carbon database. Temperature and landform type were the dominant controls on SOC distribution for selected ecoregions. Mean SOC pools (to a depth of 1-m) varied by three, seven and ten-fold across ecoregion, landform, and ecosystem types, respectively. Climate interactions with landform type and SOC were greatest in the uplands. For upland SOC there was a six-fold non-linear increase in SOC with latitude (i.e., temperature) where SOC was lowest in the Intermontane Boreal compared to the Arctic Tundra and Coastal Rainforest. Additionally, in upland systems mineral SOC pools decreased as climate became more continental, suggesting that the lower productivity, higher decomposition rates and fire activity, common in continental climates, interacted to reduce mineral SOC. For lowland systems, in contrast, these interactions and their impacts on SOC were muted or absent making SOC in these environments more comparable across latitudes. Thus, the magnitudes of SOC change across temperature gradients were non-uniform and depended on landform type. Additional factors that appeared to be related to SOC distribution within ecoregions included stand age, aspect, and permafrost presence or absence in black spruce stands. Overall, these results indicate the influence of major interactions between temperature-controlled decomposition and topography on SOC in high-latitude systems. However, there remains a need for more SOC data from wetlands and boreal-region permafrost soils, especially at depths > 1 m in

  17. Soil color indicates carbon and wetlands: developing a color-proxy for soil organic carbon and wetland boundaries on sandy coastal plains in South Africa.

    Science.gov (United States)

    Pretorius, M L; Van Huyssteen, C W; Brown, L R

    2017-10-13

    A relationship between soil organic carbon and soil color is acknowledged-albeit not a direct one. Since heightened carbon contents can be an indicator of wetlands, a quantifiable relationship between color and carbon might assist in determining wetland boundaries by rapid, field-based appraisal. The overarching aim of this initial study was to determine the potential of top soil color to indicate soil organic carbon, and by extension wetland boundaries, on a sandy coastal plain in South Africa. Data were collected from four wetland types in northern KwaZulu-Natal in South Africa. Soil samples were taken to a depth of 300 mm in three transects in each wetland type and analyzed for soil organic carbon. The matrix color was described using a Munsell soil color chart. Various color indices were correlated with soil organic carbon. The relationship between color and carbon were further elucidated using segmented quantile regression. This showed that potentially maximal carbon contents will occur at values of low color indices, and predictably minimal carbon contents will occur at values of low or high color indices. Threshold values can thus be used to make deductions such as "when the sum of dry and wet Value and Chroma values is 9 or more, carbon content will be 4.79% and less." These threshold values can then be used to differentiate between wetland and non-wetland sites with a 70 to 100% certainty. This study successfully developed a quantifiable correlation between color and carbon and showed that wetland boundaries can be determined based thereon.

  18. Irrigating grazed pasture decreases soil carbon and nitrogen stocks.

    Science.gov (United States)

    Mudge, Paul L; Kelliher, Francis M; Knight, Trevor L; O'Connell, Denis; Fraser, Scott; Schipper, Louis A

    2017-02-01

    The sustainability of using irrigation to produce food depends not only on the availability of sufficient water, but also on the soil's 'response' to irrigation. Stocks of carbon (C) and nitrogen (N) are key components of soil organic matter (SOM), which is important for sustainable agricultural production. While there is some information about the effects of irrigation on soil C stocks in cropping systems, there is a paucity of such studies in pastoral food production systems. For this study, we sampled soils from 34 paired, irrigated and unirrigated pasture sites across New Zealand (NZ) and analysed these for total C and N. On average, irrigated pastures had significantly (P stocks and the length of time under irrigation. This study suggests SOM will decrease when pastures under a temperate climate are irrigated. On this basis, increasing the area of temperate pasture land under irrigation would result in more CO 2 in the atmosphere and may directly and indirectly increase N leaching to groundwater. Given the large and increasing area of land being irrigated both in NZ and on a global scale, there is an urgent need to determine whether the results found in this study are also applicable in other regions and under different land management systems (e.g. arable). © 2016 John Wiley & Sons Ltd.

  19. SOIL CARBON SEQUESTRATION IN COASTAL FRESHWATER WETLANDS OF VERACRUZ

    Directory of Open Access Journals (Sweden)

    José Luis Marín-Muñiz

    2011-11-01

    Full Text Available Wetlands play an important role in the global carbon (C cycle because they act as sinks of this element. Vegetation in the wetlands is a factor that influences C storage in these ecosystems. We investigated C storage in freshwater wetland soils with different types of vegetation (swamps and marshes in the coastal plain of Veracruz, Mexico. The study sites were: Estero Dulce (ED, Tecolutla and Laguna Chica (LCH, Vega de Alatorre. Bulk densities observed ranged from 0.1 to 1.15 g cm3. Average C stored in LCH was higher in swamp (13.30±0.11 % than in marsh soils (4.52±0.02 %. However, in ED the C content was similar in swamp (5.88±0.03 % and marsh soils (5.28±0.02 %. In LCH marshes, there was approximately 50 % less total C in the soil compared to the C content in the swamps. In ED, the C stored in the marshes was only 7.15 % lower than the C stored in the swamps. When the total C storage of freshwater swamps (35.04±4.0 kg cm-2 and marshes (24.8±4.0 kg cm-2 was compared, there was no effect caused by the type of vegetation (P = 0.213.

  20. Feedback of global warming to soil carbon cycling in forest ecosystems

    International Nuclear Information System (INIS)

    Nakane, Kaneyuki

    1993-01-01

    Thus in this study the simulation of soil carbon cycling and dynamics of its storage in several types of mature forests developed from the cool-temperate to the tropics was carried out for quantitatively assessing carbon loss from the soil under several scenarios of global warming, based on the model of soil carbon cycling in forest ecosystems (Nakane et al. 1984, 1987 and Nakane 1992). (J.P.N.)

  1. Soil respiration and rates of soil carbon turnover differ among six common European tree species

    DEFF Research Database (Denmark)

    Vesterdal, Lars; Elberling, Bo; Christiansen, Jesper Riis

    2012-01-01

    moisture. Carbon turnover rates based on the ratio between R h and C stock were significantly higher in ash than in all other species except maple, and maple also had higher C turnover than spruce. A similar influence of tree species on C turnover was indicated by the litterfall C to forest floor C ratio...... and by foliar mass loss; rates of C turnover increased in the order sprucesignificant differences between several of the species. Mineral soil C turnover during laboratory incubation was highest for ash, maple and oak, and significantly lower for spruce. The indices of soil C...... turnover indices that integrated the forest floor. The results suggests that specific traits of Norway spruce and these five common broadleaf forest species should be taken into account in the modelling of soil C stock dynamics over decades....

  2. 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)

  3. Isotope evidence for soil organic carbon pools with distinct turnover rates—II. Humic substances

    OpenAIRE

    Lichtfouse, Eric; Dou, Sen; Houot, Sabine; Barriuso, Enrique

    1995-01-01

    International audience; Two experiments using 13C-enriched substrates have been undertaken to evaluate the relative turnover rates of the main pools of soil organic carbon namely bulk organic carbon, humin and humic acids. Firstly, soil organic matter was labelled naturally during a 5 year field experiment by cultivating Zea mays, a C4 plant, on a soil that had previously grown isotopically distincts C3 plants, e.g. wheat. Secondly, soil organic matter was labelled artificially with either Im...

  4. Towards a global harmonized permafrost soil organic carbon stock estimates.

    Science.gov (United States)

    Hugelius, G.; Mishra, U.; Yang, Y.

    2017-12-01

    Permafrost affected soils store disproportionately large amount of organic carbon stocks due to multiple cryopedogenic processes. Previous permafrost soil organic carbon (SOC) stock estimates used a variety of approaches and reported substantial uncertainty in SOC stocks of permafrost soils. Here, we used spatially referenced data of soil-forming factors (topographic attributes, land cover types, climate, and bedrock geology) and SOC pedon description data (n = 2552) in a regression kriging approach to predict the spatial and vertical heterogeneity of SOC stocks across the Northern Circumpolar and Tibetan permafrost regions. Our approach allowed us to take into account both environmental correlation and spatial autocorrelation to separately estimate SOC stocks and their spatial uncertainties (95% CI) for three depth intervals at 250 m spatial resolution. In Northern Circumpolar region, our results show 1278.1 (1009.33 - 1550.45) Pg C in 0-3 m depth interval, with 542.09 (451.83 - 610.15), 422.46 (306.48 - 550.82), and 313.55 (251.02 - 389.48) Pg C in 0 - 1, 1 - 2, and 2 - 3 m depth intervals, respectively. In Tibetan region, our results show 26.68 (9.82 - 79.92) Pg C in 0 - 3 m depth interval, with 13.98 (6.2 - 32.96), 6.49 (1.73 - 25.86), and 6.21 (1.889 - 20.90) Pg C in 0 - 1, 1 - 2, and 2 - 3 m depth intervals, respectively. Our estimates show large spatial variability (50 - 100% coefficient of variation, depending upon the study region and depth interval) and higher uncertainty range in comparison to existing estimates. We will present the observed controls of different environmental factors on SOC at the AGU meeting.

  5. Soil organic carbon pools and stocks in permafrost-affected soils on the tibetan plateau.

    Science.gov (United States)

    Dörfer, Corina; Kühn, Peter; Baumann, Frank; He, Jin-Sheng; Scholten, Thomas

    2013-01-01

    The Tibetan Plateau reacts particularly sensitively to possible effects of climate change. Approximately two thirds of the total area is affected by permafrost. To get a better understanding of the role of permafrost on soil organic carbon pools and stocks, investigations were carried out including both discontinuous (site Huashixia, HUA) and continuous permafrost (site Wudaoliang, WUD). Three organic carbon fractions were isolated using density separation combined with ultrasonic dispersion: the light fractions (1.6 g cm(-3)) of mineral associated organic matter (MOM). The fractions were analyzed for C, N, and their portion of organic C. FPOM contained an average SOC content of 252 g kg(-1). Higher SOC contents (320 g kg(-1)) were found in OPOM while MOM had the lowest SOC contents (29 g kg(-1)). Due to their lower density the easily decomposable fractions FPOM and OPOM contribute 27% (HUA) and 22% (WUD) to the total SOC stocks. In HUA mean SOC stocks (0-30 cm depth) account for 10.4 kg m(-2), compared to 3.4 kg m(-2) in WUD. 53% of the SOC is stored in the upper 10 cm in WUD, in HUA only 39%. Highest POM values of 36% occurred in profiles with high soil moisture content. SOC stocks, soil moisture and active layer thickness correlated strongly in discontinuous permafrost while no correlation between SOC stocks and active layer thickness and only a weak relation between soil moisture and SOC stocks could be found in continuous permafrost. Consequently, permafrost-affected soils in discontinuous permafrost environments are susceptible to soil moisture changes due to alterations in quantity and seasonal distribution of precipitation, increasing temperature and therefore evaporation.

  6. Soil organic carbon pools and stocks in permafrost-affected soils on the tibetan plateau.

    Directory of Open Access Journals (Sweden)

    Corina Dörfer

    Full Text Available The Tibetan Plateau reacts particularly sensitively to possible effects of climate change. Approximately two thirds of the total area is affected by permafrost. To get a better understanding of the role of permafrost on soil organic carbon pools and stocks, investigations were carried out including both discontinuous (site Huashixia, HUA and continuous permafrost (site Wudaoliang, WUD. Three organic carbon fractions were isolated using density separation combined with ultrasonic dispersion: the light fractions (1.6 g cm(-3 of mineral associated organic matter (MOM. The fractions were analyzed for C, N, and their portion of organic C. FPOM contained an average SOC content of 252 g kg(-1. Higher SOC contents (320 g kg(-1 were found in OPOM while MOM had the lowest SOC contents (29 g kg(-1. Due to their lower density the easily decomposable fractions FPOM and OPOM contribute 27% (HUA and 22% (WUD to the total SOC stocks. In HUA mean SOC stocks (0-30 cm depth account for 10.4 kg m(-2, compared to 3.4 kg m(-2 in WUD. 53% of the SOC is stored in the upper 10 cm in WUD, in HUA only 39%. Highest POM values of 36% occurred in profiles with high soil moisture content. SOC stocks, soil moisture and active layer thickness correlated strongly in discontinuous permafrost while no correlation between SOC stocks and active layer thickness and only a weak relation between soil moisture and SOC stocks could be found in continuous permafrost. Consequently, permafrost-affected soils in discontinuous permafrost environments are susceptible to soil moisture changes due to alterations in quantity and seasonal distribution of precipitation, increasing temperature and therefore evaporation.

  7. Exploring Soil Organic Carbon Deposits in a Bavarian Catchment

    Science.gov (United States)

    Kriegs, Stefanie; Hobley, Eleanor; Schwindt, Daniel; Völkel, Jörg; Kögel-Knabner, Ingrid

    2017-04-01

    The distribution of soil organic carbon (SOC) in the landscape is not homogeneous, but shows high variability from the molecular to the landscape scale. The aims of our work are 1.) to detect hot spots of SOC storage within different positions in a landscape; 2.) to outline differences (or similarities) between SOC characteristics of erosional and accumulative landscape positions; and 3.) to determine whether localised SOC deposits are dominated by fresh and labile organic matter (OM) or old and presumably stable OM. These findings are crucial for the evaluation of the landscapés vulnerability towards SOC losses caused by management or natural disturbances such as erosional rainfall events. Sampling sites of our study are located in a catchment at the foothills of the Bavarian Forest in south-east Germany. Within this area three landform positions were chosen for sampling: a) a slope with both erosional depletion and old colluvial deposits, b) a foothill with recent colluvial deposits and c) a floodplain with alluvial deposits. In order to consider both heterogeneity within a single landform position and between landforms several soil profiles were sampled at every position. Samples were taken to a maximal depth of 150 cm, depending on the presence of rocks or ground-water level, and analysed for bulk density, total carbon (TOC), inorganic carbon (IC) and texture. SOC densities and stocks were calculated. A two-step physical density fractionation using Sodium-Polytungstate (1.8 g/cm3 and 2.4 g/cm3) was applied to determine the contribution of the different soil organic matter fractions to the detected SOC deposits. Literature assumes deep buried SOC to be particularly old and stable, so we applied Accelerator Mass Spectrometry Radiocarbon Dating (AMS 14C) to bulk soil samples in order to verify this hypothesis. The results show that the floodplain soils contain higher amounts of SOC compared with slopes and foothills. Heterogeneity within the sites was smaller

  8. Recrystallization of biogenic carbonates in soils: consequences for palaeological studies

    Science.gov (United States)

    Zamanian, Kazem; Pustovoytov, Konstantin; Kuzyakov, Yakov

    2015-04-01

    The isotopic signatures of biogenic carbonate (BC) in fossils are commonly used to assess environmental conditions during the life time of organisms, their diets and extinction periods. As a proxy, BC represents in many cases the only alternative to organic matter. However, BC in fossils may dissolve in embedded matrix and recrystallize with CO2 respired by roots and microorganisms. Consequently, isotopic composition of BC can be re-equilibrated and the original paleoenvironmental signal may be lost. The dynamics of these processes still remains poorly understood. Here the results of BC recrystallization under controlled conditions have been presented. We aimed 1) To determine the recrystallization amounts of BC as a function of time, 2) To investigate the effects of geogenic carbonates (GC) availability in embedded matrix on recrystallization rate of BC and 3) To evaluate the effects of organic matter (OM) presence in the BC structure on its recrystallization. Loess and a loamy soil were selected as carbonate containing and carbonate free matrixes, respectively. Shells of 'Pacific little-neck clams (Protothaca staminea)' were selected as BC. To evaluate the role of OM presence in the BC structure, heated (550?C) and not heated shells were used. The shells were washed by means of ultrasonic and crashed to a size of 2-2.5 mm. The 14C labeled CO2 (pCO2= 2%) was injected into the airtight bottles. The samples were incubated at room temperature and water content of 60% of water holding capacity of matrixes for 1, 3, 10, 21 and 56 days. At each time the 14C activity was measured in bottle air, dissolved organic and inorganic carbon, matrixes and the shells. The recrystallization of shells started even after one day of incubation. However, the amounts of recrystallization were increased by the time. The recrystallization of CaCO3 was higher in shells without OM. Elimination of OM probably increases the porosity of shell structure and led to better water penetration into

  9. Land Cover Differences in Soil Carbon and Nitrogen at Fort Benning, Georgia

    Energy Technology Data Exchange (ETDEWEB)

    Garten Jr., C.T.

    2004-02-09

    Land cover characterization might help land managers assess the impacts of management practices and land cover change on attributes linked to the maintenance and/or recovery of soil quality. However, connections between land cover and measures of soil quality are not well established. The objective of this limited investigation was to examine differences in soil carbon and nitrogen among various land cover types at Fort Benning, Georgia. Forty-one sampling sites were classified into five major land cover types: deciduous forest, mixed forest, evergreen forest or plantation, transitional herbaceous vegetation, and barren land. Key measures of soil quality (including mineral soil density, nitrogen availability, soil carbon and nitrogen stocks, as well as properties and chemistry of the O-horizon) were significantly different among the five land covers. In general, barren land had the poorest soil quality. Barren land, created through disturbance by tracked vehicles and/or erosion, had significantly greater soil density and a substantial loss of carbon and nitrogen relative to soils at less disturbed sites. We estimate that recovery of soil carbon under barren land at Fort Benning to current day levels under transitional vegetation or forests would require about 60 years following reestablishment of vegetation. Maps of soil carbon and nitrogen were produced for Fort Benning based on a 1999 land cover map and field measurements of soil carbon and nitrogen stocks under different land cover categories.

  10. Climate effect on soil enzyme activities and dissolved organic carbon in mountain calcareous soils: a soil-transplant experiment

    Science.gov (United States)

    Puissant, Jérémy; Cécillon, Lauric; Mills, Robert T. E.; Gavazov, Konstantin; Robroek, Bjorn J. M.; Spiegelberger, Thomas; Buttler, Alexandre; Brun, Jean-Jacques

    2013-04-01

    Mountain soils store huge amounts of carbon as soil organic matter (SOM) which may be highly vulnerable to the strong climate changes that mountain areas currently experience worldwide. Climate modifications are expected to impact microbial activity which could change the rate of SOM decomposition/accumulation, thereby questioning the net C source/sink character of mountain soils. To simulate future climate change expected in the 21st century in the calcareous pre-Alps, 15 blocks (30 cm deep) of undisturbed soil were taken from a mountain pasture located at 1400 m a.s.l. (Marchairuz, Jura, Switzerland) and transplanted into lysimeters at the same site (control) and at two other sites located at 1000 m a.s.l. and 600 m a.s.l. (5 replicates per site). This transplantation experiment which started in 2009 simulates a climate warming with a temperature increase of 4° C and a decreased humidity of 40 % at the lowest site. In this study, we used soil extracellular enzyme activities (EEA) as functional indicators of SOM decomposition to evaluate the effect of climate change on microbial activity and SOM dynamics along the seasons. Dissolved organic carbon (DOC) was also measured to quantify the assimilable carbon for microorganism. In autumn 2012, a first sampling step out of four (winter, spring and summer 2013) has been realized. We extracted 15 cm deep soil cores from each transplant (x15) and measured (i) DOC and (ii) the activities of nine different enzymes. Enzymes were chosen to represent the degradation of the most common classes of biogeochemical compounds in SOM. β-glucosidase, β-D-cellubiosidase, β-Xylosidase, N-acetyl-β-glucosaminidase, leucine aminopeptidase, lipase, phenoloxidase respectively represented the degradation of sugar, cellulose, hemicellulose, chitin, protein, lipid and lignin. Moreover, the fluorescein diacetate (FDA) hydrolysis was used to provide an estimate of global microbial activity and phosphatase was used to estimate phosphorus

  11. Modelling soil organic carbon stocks along topographic transects under climate change scenarios using CarboSOIL

    Science.gov (United States)

    Kotb Abd-Elmabod, Sameh; Muñoz-Rojas, Miriam; Jordán, Antonio; Anaya-Romero, María; de la Rosa, Diego

    2014-05-01

    CarboSOIL is a land evaluation model for soil organic carbon (SOC) accounting under global change scenarios (Muñoz-Rojas et al., 2013a; 2013b) and is a new component of the MicroLEIS Decision Support System. MicroLEIS is a tool for decision-makers dealing with specific agro-ecological problems as, for example, soil contamination risks (Abd-Elmabod et al., 2010; Abd-Elmabod et al., 2012)which has been designed as a knowledge-based approach incorporating a set of interlinked data bases. Global change and land use changes in recent decades have caused relevant impacts in vegetation carbon stocks (Muñoz-Rojas et al., 2011) and soil organic carbon stocks, especially in sensible areas as the Mediterranean region (Muñoz-Rojas et al., 2012a; 2012b). This study aims to investigate the influence of topography, climate, land use and soil factors on SOC stocks by the application of CarboSOIL in a representative area of the Mediterranean region (Seville, Spain). Two topographic transects (S-N and W-E oriented) were considered, including 63 points separated 4 km each. These points are associated to 41 soil profiles extracted from the SDBm soil data base (De la Rosa et al., 2001) and climatic information (average minimum temperature, average maximum temperature and average rainfall per month) extracted from raster data bases (Andalusian Environmental Information Network, REDIAM). CarboSOIL has been applied along topographic transects at different soil depths and under different climate change scenarios. Climate scenarios have been calculated according to the global climate model (CNRMCM3) by extracting spatial climate data under IPCC A1B scenario for the current period (average data from 1960-2000), 2040, 2070 and 2100. In the current scenario, results show that the highest SOC stock values located on Typic Haploxeralfs under olive groves for soil sections 0-25 cm and for 25-50 cm, but the highest values were determined on fruit-cropped Rendolic Xerothent in the 50-75cm

  12. Assessing soil carbon lability by near infrared spectroscopy and NaOCL oxidation

    DEFF Research Database (Denmark)

    Thomsen, Ingrid Kaag; Bruun, Sander; Jensen, Lars Stoumann

    2009-01-01

    The feasibility of near infrared (NIR) spectroscopy for quantifying labile organic matter (OM) in arable soils and for predicting soil refractory OM fractions was tested on 37 soils varying in texture and soil carbon (C) content. Three sets of arable soils (0-20 cm depth) were sampled from 1) long...... incubated for 34 weeks while refractory OM was obtained by NaOCl oxidation. The labile fraction of the soil C accounted for 2-12% of the total soil C content. No systematic relationship between labile C content and total soil C or clay was found, but NIR spectra could be correlated well with the labile C...

  13. Carbon storage in soils of Southeastern Nigeria under different management practices

    Directory of Open Access Journals (Sweden)

    Anikwe Martin AN

    2010-09-01

    Full Text Available Abstract Background Changes in agricultural practices-notably changes in crop varieties, application of fertilizer and manure, rotation and tillage practices-influence how much and at what rate carbon is stored in, or released from, soils. Quantification of the impacts of land use on carbon stocks in sub-Saharan Africa is challenging because of the spatial heterogeneity of soil, climate, management conditions, and due to the lack of data on soil carbon pools of most common agroecosystems. This paper provides data on soil carbon stocks that were collected at 10 sites in southeastern Nigeria to characterize the impact of soil management practices. Results The highest carbon stocks, 7906-9510 gC m-2, were found at the sites representing natural forest, artificial forest and artificial grassland ecosystems. Continuously cropped and conventionally tilled soils had about 70% lower carbon stock (1978-2822 gC m-2. Thus, the soil carbon stock in a 45-year old Gmelina forest was 8987 gC m-2, whereas the parts of this forest, that were cleared and continuously cultivated for 15 years, had 75% lower carbon stock (1978 gC m-2. The carbon stock of continuously cropped and conventionally tilled soils was also 25% lower than the carbon stock of the soil cultivated by use of conservation tillage. Conclusion Introducing conservation tillage practices may reduce the loss of soil carbon stocks associated with land conversion. However, the positive effect of conservation tillage is not comparable to the negative effect of land conversion, and may not result in significant accumulation of carbon in southeastern Nigeria soils.

  14. 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.

  15. Plant stimulation of soil microbial community succession: how sequential expression mediates soil carbon stabilization and turnover

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, Mary [Univ. of California, Berkeley, CA (United States)

    2015-03-31

    It is now understood that most plant C is utilized or transformed by soil microorganisms en route to stabilization. Hence the composition of microbial communities that mediate decomposition and transformation of root C is critical, as are the metabolic capabilities of these communities. The change in composition and function of the C-transforming microbial communities over time in effect defines the biological component of soil C stabilization. Our research was designed to test 2 general hypotheses; the first two hypotheses are discussed first; H1: Root-exudate interactions with soil microbial populations results in the expression of enzymatic capacities for macromolecular, complex carbon decomposition; and H2: Microbial communities surrounding roots undergo taxonomic succession linked to functional gene activities as roots grow, mature, and decompose in soil. Over the term of the project we made significant progress in 1) quantifying the temporal pattern of root interactions with the soil decomposing community and 2) characterizing the role of root exudates in mediating these interactions.

  16. Effect of Different Cultivation Periods on Soil Stable Organic Carbon Pool in Citrus Orchard

    Directory of Open Access Journals (Sweden)

    WANG Yi-xiang

    2015-08-01

    Full Text Available Effect of different cultivation periods on soil stable organic carbon pools and fractions in citrus orchard was investigated to provide scientific basis on the study of orchard soil carbon sequestration by the temporal-spatial substitution method and physical and chemical fractionation method. The results showed that the citrus orchard planted in 1954 compared with the citrus orchard planted in 1980, the content of total organic carbon increased by 27.16%, organic carbon content in macro-aggregates increased by 13.59%, organic carbon content in micro-aggregates increased by 80.19%, organic carbon content of heavy fraction increased by 29.25%, resistant organic carbon content increased by 32.00%, black carbon content increased by 4.01%. Organic carbon which combined with micro-aggregates was protected, and resistant organic carbon and black carbon were recalcitrant organic carbon in soil, this indicated that the stable organic carbon fractions gradually enriched in soil with the increase of growing periods, which was conducive to improve carbon sink in citrus orchard soil.

  17. Role of organic soils in the world carbon cycle: problem analysis and research needs

    Energy Technology Data Exchange (ETDEWEB)

    Armentano, T.V. (ed.)

    1980-02-01

    In May 1979, The Institute of Ecology held a workshop to determine the role of organic soils in the global carbon cycle and to ascertain their past, present and future significance in world carbon flux. Wetlands ecologists and soil scientists who participated in the workshop examined such topics as Soils as Sources of Atmospheric CO/sub 2/, Organic Soils, Primary Production and Growth of Wetlands Ecosystems, and Management of Peatlands. The major finding of the workshop is that the organic soils are important in the overall carbon budget. Histosols and Gleysols, the major organic soil deposits of the world, normally sequester organic carbon fixed by plants. They may now be releasing enough carbon to account for nearly 10% of the annual rise in atmospheric content of CO/sub 2/.

  18. Evaluation of carbon storage in soil and plant biomass of primary ...

    African Journals Online (AJOL)

    USER

    Organic carbon in biomass was estimated by using allometry equation and soil carbon concentration was analyzed by. Walkley-Black method. The results revealed that PMDF ... planting in future restoration processes in order to accelerate natural succession and storage carbon. ..... Temporal evolution of carbon budgets.

  19. Carbon leaching from tropical peat soils and consequences for carbon balances

    Directory of Open Access Journals (Sweden)

    Tim Rixen

    2016-07-01

    Full Text Available Drainage and deforestation turned Southeast (SE Asian peat soils into a globally important CO2 source, because both processes accelerate peat decomposition. Carbon losses through soil leaching have so far not been quantified and the underlying processes have hardly been studied. In this study, we use results derived from nine expeditions to six Sumatran rivers and a mixing model to determine leaching processes in tropical peat soils, which are heavily disturbed by drainage and deforestation. Here we show that a reduced evapotranspiration and the resulting increased freshwater discharge in addition to the supply of labile leaf litter produced by re-growing secondary forests increase leaching of carbon by ~200%. Enhanced freshwater fluxes and leaching of labile leaf litter from secondary vegetation appear to contribute 38% and 62% to the total increase, respectively. Decomposition of leached labile DOC can lead to hypoxic conditions in rivers draining disturbed peatlands. Leaching of the more refractory DOC from peat is an irrecoverable loss of soil that threatens the stability of peat-fringed coasts in SE Asia.

  20. Effects of agricultural intensification in the tropics on soil carbon losses and soil fertility

    Science.gov (United States)

    Guillaume, Thomas; Buttler, Alexandre; Kuzyakov, Yakov

    2016-04-01

    Tropical forest conversion to agricultural land leads to strong decrease of soil organic carbon (SOC). Nonetheless, the impacts of SOC losses on soil fertility remain unclear. We quantified SOC losses in forest, oil palm plantations, extensive rubber plantations and rubber monocultures on Sumatra Island (Indonesia). Furthermore, we assessed the response of biological (basal respiration, microbial biomass, acid phosphatase) and chemical fertility indicators (light fraction of OM, DOC, total N, available P) to SOC losses. We used a new approach based on (non-)linear regressions between SOC losses and the indicators, normalized to natural ecosystem values, to assess the sensitivity or resistance of fertility indicators to SOC losses. Carbon contents in the Ah horizon under oil palm and intensive rubber plantations were strongly reduced: up to 70% and 62%, respectively. The decrease was lower under extensive rubber (41%). The negative impact of land-use changes on all measured indicators increased in the following sequence: extensive rubber oil palm. Basal respiration, microbial biomass and nutrients were comparatively resistant to SOC losses, whereas the light fraction of OM was lost faster than the SOC. The resistance of the microbial activity to SOC losses is an indication that microbial-mediated soil functions sustain SOC losses. However, responses of basal respiration and microbial biomass to SOC losses were non-linear. Below 2.7% C content, the relationship was reversed. The basal respiration decreased faster than the SOC, resulting in a stronger drop of microbial activity under oil palm compared to rubber, despite small difference in C content. We conclude that the new approach allows a quantitative assessment of the sensitivity and threshold of various soil functions to land-use changes and consequently, can be used to assess their resistance to agricultural intensification. Therefore, this method is appropriate to evaluate the environmental impacts associated

  1. Mapping soil organic carbon stock in the area of Neamtu Catchment, Northeastern Romania

    Science.gov (United States)

    Breaban, Ana-Ioana; Bobric, Elena-Diana; Breaban, Iuliana-Gabriela; Rusu, Eugen

    2017-04-01

    The quantification of soil organic carbon stocks and its spatial extent is directly influenced by the land cover. The aim of the study is to quantify both the spatial distribution of soil organic carbon and stocks under different soil types and land uses in an area of 41.808,04 ha in northeastern part of Romania. It has been studied the evolution of carbon stocks over time, taking into account the change of land use between 1990-2012 under 5 classes: forests, pastures, arable land, orchard and built spaces. Common soils are Cambisols, Fluvisols, Phaezems, and Luvisols, forest being the predominant land use. The most important loss of soil organic carbon occurs as a result of changes in the supply of biomass supplying litter and therefore the process of bioaccumulation. The samples were collected from 100 representative soil profiles and analyzed with Analytik Jena multi N/C 2100 with HT 1300 solid module. Based on the soil organic carbon, C/N ratio and texture the values of those parameters varied from high values in Ao and Bv horizons to lower values in C horizon. In order to model soil organic carbon concentration were used different interpolation techniques (regression and ordinary -kriging, IDW) at different sampling densities for each depth to 100 cm, using a Gaussian approach to estimate the uncertainty. It is noticeable that soil organic carbon had a positive correlation with different types of land uses and a negative correlation with the elevation, being a decreasing trend of the carbon stocks sequestered in biomass, litter and soil. In the upper part of the profiles, the soil organic carbon stock considerably varied for forest land between 6.5-7.23 kg C/sqm) and agricultural land (3.67-4.65 kg C/sqm). The kriging regression evidenced a good variability of the calculated root mean square errors of the predicted soil organic carbon stocks.

  2. Calibration and analysis of soil carbon efflux estimates with closed chambers at Forsmark and Laxemar

    International Nuclear Information System (INIS)

    Tagesson, Torbern

    2006-08-01

    The Forsmark and the Laxemar investigation areas are examined by the Swedish Nuclear Fuel and Waste Management Co. for a possible construction of a deep repository for nuclear waste. In the case of a future leakage of waste, the radioactive isotopes could end up in the ecosystems above the repository. The fate of the radionuclides and their possible radiological impacts are then highly determined by ecosystem carbon cycling. An important part of the carbon cycling is the soil carbon effluxes, and in the investigation areas soil carbon effluxes have been examined with the closed chamber technique. This paper is divided into two parts. Firstly, there were problems with the equipment measuring the soil carbon dioxide efflux, and the first part is a description of the problem, how it was corrected and its possible causes. The second part is a manual in how to analyse data and calculate annual estimates of soil carbon efflux. The field measurement by the EGM-4 is just an occasional estimate of the soil carbon efflux at a certain spot and at a certain point in time. To make an interpretation of the measurements, it is essential to analyse the data and to temporally extrapolate them. It is necessary to prepare the raw data for the analysis. The problems with the EGM-4 doing the measurements at the Forsmark and the Laxemar investigation area makes it necessary to correct the data taken up by this EGM-4. The data should also be separated into soil respiration and gross primary production (GPP). Soil carbon dioxide effluxes should be changed to soil carbon effluxes. Soil carbon effluxes are strongly controlled by abiotic factors; temperature is the main factor to influence soil respiration and photosynthetically active radiation (PAR) and air temperature are the main factors to influence GPP. Regression with soil respiration against temperature and with GPP against PAR or temperature can therefore be done. These equations can then be used on datasets with temperature and PAR

  3. Modelling carbon dioxide emissions from agricultural soils in Canada.

    Science.gov (United States)

    Yadav, Dhananjay; Wang, Junye

    2017-11-01

    Agricultural soils are a leading source of atmospheric greenhouse gas (GHG) emissions and are major contributors to global climate change. Carbon dioxide (CO 2 ) makes up 20% of the total GHG emitted from agricultural soil. Therefore, an evaluation of CO 2 emissions from agricultural soil is necessary in order to make mitigation strategies for environmental efficiency and economic planning possible. However, quantification of CO 2 emissions through experimental methods is constrained due to the large time and labour requirements for analysis. Therefore, a modelling approach is needed to achieve this objective. In this paper, the DeNitrification-DeComposition (DNDC), a process-based model, was modified to predict CO 2 emissions for Canada from regional conditions. The modified DNDC model was applied at three experimental sites in the province of Saskatchewan. The results indicate that the simulations of the modified DNDC model are in good agreement with observations. The agricultural management of fertilization and irrigation were evaluated using scenario analysis. The simulated total annual CO 2 flux changed on average by ±13% and ±1% following a ±50% variance of the total amount of N applied by fertilising and the total amount of water through irrigation applications, respectively. Therefore, careful management of irrigation and applications of fertiliser can help to reduce CO 2 emissions from the agricultural sector. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Assessing soil carbon stocks under pastures through orbital remote sensing

    Directory of Open Access Journals (Sweden)

    Gabor Gyula Julius Szakács

    2011-10-01

    Full Text Available The growing demand of world food and energy supply increases the threat of global warming due to higher greenhouse gas emissions by agricultural activity. Therefore, it is widely admitted that agriculture must establish a new paradigm in terms of environmental sustainability that incorporate techniques for mitigation of greenhouse gas emissions. This article addresses to the scientific demand to estimate in a fast and inexpensive manner current and potential soil organic carbon (SOC stocks in degraded pastures, using remote sensing techniques. Four pastures on sandy soils under Brazilian Cerrado vegetation in São Paulo state were chosen due to their SOC sequestration potential, which was characterized for the soil depth 0-50 cm. Subsequently, a linear regression analysis was performed between SOC and Leaf Area Index (LAI measured in the field (LAIfield and derived by satellite (LAIsatellite as well as SOC and pasture reflectance in six spectra from 450 nm - 2350 nm, using the Enhanced Thematic Mapper (ETM+ sensor of satellite Landsat 7. A high correlation between SOC and LAIfield (R² = 0.9804 and LAIsatellite (R² = 0.9812 was verified. The suitability of satellite derived LAI for SOC determination leads to the assumption, that orbital remote sensing is a very promising SOC estimation technique from regional to global scale.

  5. Developing an Enzyme Mediated Soil Organic Carbon Decomposition Model

    Science.gov (United States)

    Mayes, M. A.; Post, W. M.; Wang, G.; Jagadamma, S.; Steinweg, J. M.; Schadt, C. W.

    2012-12-01

    We developed the Microbial-ENzyme-mediated Decomposition (MEND) model in order to mechanistically model the decomposition of soil organic carbon (C). This presentation is an overview of the concept and development of the model and of the design of complementary lab-scale experiments. The model divides soil C into five pools of particulate, mineral-associated, dissolved, microbial, and enzyme organic C (Wang et al. 2012). There are three input types - cellulose, lignin, and dissolved C. Decomposition is mediated via microbial extracellular enzymes using the Michaelis-Menten equation, resulting in the production of a common pool of dissolved organic C. Parameters for the Michaelis-Menten equation are obtained through a literature review (Wang and Post, 2012a). The dissolved C is taken up by microbial biomass and proportioned according to microbial maintenance and growth, which were recalculated according to Wang and Post (2012b). The model allows dissolved C to undergo adsorption and desorption reactions with the mineral-associated C, which was also parameterized based upon a literature review and complementary laboratory experiments. In the lab, four 14C-labeled substrates (cellulose, fatty acid, glucose, and lignin-like) were incubated with either the particulate C pool, the mineral-associated C pool, or to bulk soils. The rate of decomposition was measured via the production of 14CO2 over time, along with incorporation into microbial biomass, production of dissolved C, and estimation of sorbed C. We performed steady-state and dynamic simulations and sensitivity analyses under temperature increases of 1-5°C for a period of 100 y. Simulations indicated an initial decrease in soil organic C consisting of both cellulose and lignin pools. Over longer time intervals (> 6 y), however, a shrinking microbial population, a concomitant decrease in enzyme production, and a decrease in microbial carbon use efficiency together decreased CO2 production and resulted in greater

  6. Key biogeochemical factors affecting soil carbon storage in Posidonia meadows

    Science.gov (United States)

    Serrano, Oscar; Ricart, Aurora M.; Lavery, Paul S.; Mateo, Miguel Angel; Arias-Ortiz, Ariane; Masque, Pere; Rozaimi, Mohammad; Steven, Andy; Duarte, Carlos M.

    2016-08-01

    Biotic and abiotic factors influence the accumulation of organic carbon (Corg) in seagrass ecosystems. We surveyed Posidonia sinuosa meadows growing in different water depths to assess the variability in the sources, stocks and accumulation rates of Corg. We show that over the last 500 years, P. sinuosa meadows closer to the upper limit of distribution (at 2-4 m depth) accumulated 3- to 4-fold higher Corg stocks (averaging 6.3 kg Corg m-2) at 3- to 4-fold higher rates (12.8 g Corg m-2 yr-1) compared to meadows closer to the deep limits of distribution (at 6-8 m depth; 1.8 kg Corg m-2 and 3.6 g Corg m-2 yr-1). In shallower meadows, Corg stocks were mostly derived from seagrass detritus (88 % in average) compared to meadows closer to the deep limit of distribution (45 % on average). In addition, soil accumulation rates and fine-grained sediment content (stocks and accumulation rates accumulated over the last 500 years in bare sediments (0.6 kg Corg m-2 and 1.2 g Corg m-2 yr-1) were 3- to 11-fold lower than in P. sinuosa meadows, while fine-grained sediment content (1 %) and seagrass detritus contribution to the Corg pool (20 %) were 8- and 3-fold lower than in Posidonia meadows, respectively. The patterns found support the hypothesis that Corg storage in seagrass soils is influenced by interactions of biological (e.g., meadow productivity, cover and density), chemical (e.g., recalcitrance of Corg stocks) and physical (e.g., hydrodynamic energy and soil accumulation rates) factors within the meadow. We conclude that there is a need to improve global estimates of seagrass carbon storage accounting for biogeochemical factors driving variability within habitats.

  7. Effects of Pedogenic Fe Oxides on Soil Aggregate-Associated Carbon

    Science.gov (United States)

    Asefaw Berhe, A.; Jin, L.

    2017-12-01

    Carbon sequestration is intimately related to the soil structure, mainly soil aggregate dynamics. Carbon storage in soil aggregates has been recognized as an important carbon stabilization mechanism in soils. Organic matter and pedogenic Fe oxides are major binding agents that facilitate soil aggregate formation and stability. However, few studies have investigated how different forms of pedogenic Fe oxides can affect soil carbon distribution in different aggregate-size fractions. We investigated sequentially extracted pedogenic Fe oxides (in the order of organically complexed Fe extracted with sodium pyrophosphate, poorly-crystalline Fe oxides extracted with hydroxylamine hydrochloride, and crystalline Fe oxides extracted with dithionite hydrochloride) and determined the amount and nature of C in macroaggregates (2-0.25mm), microaggregates (0.25-0.053mm), and two silt and clay fractions (0.053-0.02mm, and <0.02mm) in Musick soil from Sierra Nevada mountain in California. We also determined how pedogenic Fe oxides affect soil carbon distribution along soil depth gradients. Findings of our study revealed that the proportion of organic matter complexed Fe decreased, but the proportion of crystalline Fe increased with increasing soil depths. Poorly crystalline Fe oxides (e.g. ferrihydrite) was identified as a major Fe oxide in surface soil, whereas crystalline Fe oxides (e.g. goethite) were found in deeper soil layers. These results suggest that high concentration of organic matter in surface soil suppressed Fe crystallization. Calcium cation was closely related to the pyrophosphate extractable Fe and C, which indicates that calcium may be a major cation that contribute to the organic matter complexed Fe and C pool. Increasing concentrations of extractable Fe and C with decreasing aggregate size fractions also suggests that Fe oxides play an important role in formation and stability of silt and clay fractions, and leading to further stabilization of carbon in soil

  8. Identifying the main drivers of soil carbon response to climate change in arctic and boreal Alaska.

    Science.gov (United States)

    Genet, H.; McGuire, A. D.; He, Y.; Johnson, K.; Wylie, B. K.; Pastick, N. J.; Zhuang, Q.; Zhu, Z.

    2015-12-01

    Boreal and arctic regions represent the largest reservoir of carbon among terrestrial biomes. Most of this carbon is stored deep in the soil in permafrost where frozen organic matter is protected from decomposition. The vulnerability of soil carbon stocks to a changing climate in high latitudes depends on a number of physical and ecological processes. The importance of these processes in controlling the dynamics of soil carbon stocks vary across regions because of variability in vegetation composition, drainage condition, and permafrost characteristics. To better understand the main drivers of the vulnerability of soil carbon stocks to climate change in Alaska, we ran a process-based ecosystem model, the Terrestrial Ecosystem Model. This model explicitly simulates interactions between the carbon cycle and permafrost dynamics and was coupled with a disturbance model and a model of biogenic methane dynamics to assess historical and projected soil carbon dynamics in Alaska, from 1950 to 2100. The uncertainties related to climate, fire regime and atmospheric CO2projections on soil carbon dynamics were quantified by running simulations using climate projections from 2 global circulation models, 3 fossil fuel emission scenarios and 3 alternative fire management scenarios. During the historical period [1950-2009], soil carbon stocks increased by 4.7 TgC/yr in Alaska. Soil carbon stocks decreased in boreal Alaska due to substantial fire activity in the early 2000's. This loss was offset by carbon accumulation in the arctic. Changes in soil carbon stocks from 2010 to 2099 ranged from 8.9 to 25.6 TgC/yr, depending on the climate projections. Soil carbon accumulation was slower in lowlands than in uplands and slower in the boreal than in the arctic regions because of the negative effect of fire activity on soil carbon stocks. Tundra ecosystems were more vulnerable to carbon loss from fire than forest ecosystems because of a lower productivity. As a result, the increase in

  9. Plant-Soil Relationships of Bromus tectorum L.: Interactions among Labile Carbon Additions, Soil Invasion Status, and Fertilizer

    International Nuclear Information System (INIS)

    Blank, R.R.; Young, J.A.

    2010-01-01

    Invasion of western North America by the annual exotic grass Bromus tectorum L. (cheatgrass) has been an ecological disaster. High soil bioavailability of nitrogen is a contributing factor in the invasive potential of B. tectorum. Application of labile carbon sources to the soil can immobilize soil nitrogen and favor native species. We studied the interaction of labile carbon addition (sucrose), with soil invasion status and fertilizer addition on the growth of B. tectorum. Soils were non invaded (BNI) and B. tectorum invaded (BI). Treatments were control, sucrose, combined fertilizer, and sucrose + fertilizer. The greenhouse experiment continued for 3 growth-cycles. After the 1st growth-cycle, sucrose addition reduced B. tectorum aboveground mass almost 70 times for the BI soil but did not significantly reduce growth in the BNI soil. B. tectorum aboveground mass, after the 1st growth-cycle, was over 27 times greater for BI control soils than BNI control soils. Although sucrose addition reduced soil-solution NO 3 , tissue N was not significantly lowered, suggesting that reduction of soil available N may not be solely responsible for reduction in B. tectorum growth. Non invaded soil inhibits growth of B. tectorum. Understanding this mechanism may lead to viable control strategies.

  10. Pyrogenic Carbon Erosion: Implications for Stock and Persistence of Pyrogenic Carbon in Soil

    Directory of Open Access Journals (Sweden)

    Rebecca B. Abney

    2018-03-01

    Full Text Available Pyrogenic carbon (PyC constitutes an important pool of soil organic matter (SOM, particularly for its reactivity and because of its assumed long residence times in soil. In the past, research on the dynamics of PyC in the soil system has focused on quantifying stock and mean residence time (MRT of PyC in soil, as well as determining both PyC stabilization mechanisms and loss pathways. Much of this research has focused on decomposition as the most important loss pathway for PyC from soil. However, the low density of PyC and its high concentration on the soil surface after fire indicates that a significant proportion of PyC formed or deposited on the soil surface is likely laterally transported away from the site of production by wind and water erosion. Here, we present a synthesis of available data and literature to compare the magnitude of the water-driven erosional PyC flux with other important loss pathways, including leaching and decomposition, of PyC from soil. Furthermore, we use a simple first-order kinetic model of soil PyC dynamics to assess the effect of erosion and deposition on residence time of PyC in eroding landscapes. Current reports of PyC MRT range from 250 to 660 years. Using a specific example-based model system, we find that ignoring the role of erosion may lead to the under- or over-estimation of PyC MRT on the centennial time scale. Furthermore, we find that, depending on the specific landform positions, timescales considered, and initial concentrations of PyC in soil, ignoring the role of erosion in distributing PyC across a landscape can lead to discrepancies in PyC concentrations on the order of several 100 g PyC m−2. Erosion is an important PyC flux that can act as a significant control on the stock and residence time of PyC in the soil system.

  11. Pyrogenic carbon erosion: implications for stock and persistence of pyrogenic carbon in soil

    Science.gov (United States)

    Abney, Rebecca B.; Berhe, Asmeret Asefaw

    2018-03-01

    Pyrogenic carbon (PyC) constitutes an important pool of soil organic matter, particularly for its reactivity and because of its assumed long residence times in soil. In the past, research on the dynamics of PyC in the soil system has focused on quantifying stock and mean residence time of PyC in soil, as well as determining both PyC stabilization mechanisms and loss pathways. Much of this research has focused on decomposition as the most important loss pathway for PyC from soil. However, the low density of PyC and its high concentration on the soil surface after fire indicates that a significant proportion of PyC formed or deposited on the soil surface is likely laterally transported away from the site of production by wind and water erosion. Here, we present a synthesis of available data and literature to compare the magnitude of the water-driven erosional PyC flux with other important loss pathways, including leaching and decomposition, of PyC from soil. Furthermore, we use a simple first-order kinetic model of soil PyC dynamics to assess the effect of erosion and deposition on residence time of PyC in eroding landscapes. Current reports of PyC mean residence time (MRT) range from 250 to 660 years. Using a specific example-based model system, we find that ignoring the role of erosion may lead to the under- or over-estimation of PyC MRT on the centennial time scale. Furthermore, we find that, depending on the specific landform positions, timescales considered, and initial concentrations of PyC in soil, ignoring the role of erosion in distributing PyC across a landscape can lead to discrepancies in PyC concentrations on the order of several hundred g PyC m-2. Erosion is an important PyC flux that can act as a significant control on the stock and residence time of PyC in the soil system.

  12. Impacts of twenty years of experimental warming on soil carbon, nitrogen, moisture and soil across alpine/subarctic tundra communities

    DEFF Research Database (Denmark)

    M. Alatalo, Juha; K. Jägerbrand, Annika; Juhanson, Jaanis

    2017-01-01

    High-altitude and alpine areas are predicted to experience rapid and substantial increases in future temperature, which may have serious impacts on soil carbon, nutrient and soil fauna. Here we report the impact of 20 years of experimental warming on soil properties and soil mites in three...... contrasting plant communities in alpine/subarctic Sweden. Long-term warming decreased juvenile oribatid mite density, but had no effect on adult oribatids density, total mite density, any major mite group or the most common species. Long-term warming also caused loss of nitrogen, carbon and moisture from...... be important for buffering mites from global warming. The results indicated that juvenile mites may be more vulnerable to global warming than adult stages. Importantly, the results also indicated that global warming may cause carbon and nitrogen losses in alpine and tundra mineral soils and that its effects...

  13. Thermokarst dynamics and soil organic matter characteristics controlling initial carbon release from permafrost soils in the Siberian Yedoma region

    DEFF Research Database (Denmark)

    Weiss, Niels; Blok, Daan; Elberling, Bo

    2016-01-01

    This study relates soil organic matter (SOM) characteristics to initial soil incubation carbon release from upper permafrost samples in Yedoma region soils of northeastern Siberia, Russia. Carbon (C) and nitrogen (N) content, carbon to nitrogen ratios (C:N), δ13C and δ15N values show clear trends...... that correspond with SOM age and degree of decomposition. Incubation results indicate that older and more decomposed soil material shows higher C respiration rates per unit incubated C than younger and less decomposed samples with higher C content. This is important as undecomposed material is often assumed...... to be more reactive upon thawing. Large stocks of SOM and their potential decomposability, in combination with complex landscape dynamics that include one or more events of Holocene thaw in most of the landscape, are of consequence for potential greenhouse gas release from permafrost soils in the Yedoma...

  14. CARBON FIXING CAPACITY OF AMAZONIAN SOILS IN RELATION TO ITS DEGRADATION CONDITIONS

    Directory of Open Access Journals (Sweden)

    Clara Patricia Peña Venegas

    2015-06-01

    Full Text Available Amazonian deforestation and transformation alert about their effects worldwide. One concern is the increase of the Carbon (C levels emitted. Previous works have estimated the fixed C in Amazon forests without including the C stored in soils. Within soil, the organic carbon molecules are highly sensitive to degradation, affecting the natural capacity of soils to fix and store C. The present study evaluates the impact of degradation in the natural capacity of Amazon soils to fix C. Thirty five farms with different typology were selected in Caquetá department which hold the highest deforestation and soil degradation rates in the Colombian Amazon. Soil samples were taken from natural forest relicts, cropping areas and introduced pastures of the farms, in locations with high, intermediate and low soil degradation. Aerial biomass was estimated in pastures with different level of soil degradation. Changes in the labile C stock were estimated from the soil organic carbon and the microbial biomass using substrate induced respiration. Results showed that the main C pool is in the natural forest relicts and the crops of the farms, independently from the size or type of farm sampled. The hills with higher intervention showed the lowest soil C fixation capacities. The soil C fixation capacity was related with changes in the soil microbial composition where conserved soils store preferentially C as fungal biomass while degraded soils store C as bacterial biomass. These estimations contribute to establish the cost of sustainability and soil degradation in the Colombian Amazon.

  15. Soil organic carbon stocks assessment in Mediterranean natural areas: a comparison of entire soil profiles and soil control sections.

    Science.gov (United States)

    Parras-Alcántara, L; Lozano-García, B; Brevik, E C; Cerdá, A

    2015-05-15

    Soil organic carbon (SOC) is an important part of the global carbon (C) cycle. In addition, SOC is a soil property subject to changes and highly variable in space and time. Over time, some researches have analyzed entire soil profile (ESP) by pedogenetic horizons and other researches have analyzed soil control sections (SCS) to different thickness. However, very few studies compare both methods (ESP versus SCS). This research sought to analyze the SOC stock (SOCS) variability using both methods (ESP and SCS) in The Despeñaperros Natural Park, a nature reserve that consists of a 76.8 km(2) forested area in southern Spain. Thirty-four sampling points were selected in the study zone. Each sampling point was analyzed in two different ways, as ESP (by horizons) and as SCS with different depth increments (0-25, 25-50, 50-75 and 75-100 cm). The major goal of this research was to study the SOCS variability at regional scale. The soils investigated in this study included Phaeozems, Cambisols, Regosols and Leptosols. Total SOCS in the Despeñaperros Natural Park was over 28.2% greater when SCS were used compared to ESP, ranging from 0.8144 Tg C (10,604.2 Mg km(-2)) to 0.6353 Tg C (8272.1 Mg km(-2)) respectively (1 Tg = 10(12) g). However, when the topsoil (surface horizon and superficial section control) was analyzed, this difference increased to 59.8% in SCS compared to ESP. The comparison between ESP and SCS showed the effect of mixing pedogenetic horizons when depth increments were analyzed. This indicates an overestimate of T-SOCS when sampling by SCS. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Coupling of soil water and dissolved carbon measurements to estimate the carbon flux in forest ecosystems a case study

    Science.gov (United States)

    Fink, M.; Krause, P.; Gleixner, G.

    2003-04-01

    We used the 250 year old forest of the national park Hainich, Germany, to estimate carbon storage and export to the ground water in old grown forests. The Hainich is one of the largest deciduous forest ecosystems in middle Europe and the protected area is unmanaged for at least 50 years. It is one of the flux sites of the Carboeurop cluster (www.carboeurop.de) equipped with an eddy covariance system to measure net ecosystem exchange (NEE). Surprisingly NEE of this old grown forest is about 5 t carbon/ha*a. This high amount of carbon uptake can not be explained only by biomass or litter increase. Therefore we quantified the amount of carbon lost as dissolved carbon from the upper soil layer. To determine if carbon is washed out and transported by water fluxes in form of dissolved carbon, the measurement campaign was extended by sophisticated hydrometrical instruments, like frequency domain reflectrometry (FDR) probes, high frequency rain measurement equipment and ceramic plates to take soil water samples. The FDR probes characterize the soil hydrology and quantify the amount of water percolating horizontal and vertical through the soil. In the water samples dissolved organic carbon and dissolved inorganic carbon were determined. Both the quantification of the soil hydrology and the chemical characterization of the soil water enable the calculation of the carbon export from the system. The measurement equipment and layout will be presented and results of dissolved carbon contents in the subsurface water fluxes will be presented. Preliminary estimations of the carbon loss by seepages will be presented also.

  17. Soil organic carbon - a large scale paired catchment assessment

    Science.gov (United States)

    Kunkel, V.; Hancock, G. R.; Wells, T.

    2016-12-01

    Soil organic carbon (SOC) concentration can vary both spatially and temporally driven by differences in soil properties, topography and climate. However most studies have focused on point scale data sets with a paucity of studies examining larger scale catchments. Here we examine the spatial and temporal distribution of SOC for two large catchments. The Krui (575 km2) and Merriwa River (675km2) catchments (New South Wales, Australia). Both have similar shape, soils, topography and orientation. We show that SOC distribution is very similar for both catchments and that elevation (and associated increase in soil moisture) is a major influence on SOC. We also show that there is little change in SOC from the initial assessment in 2006 to 2015 despite a major drought from 2003 to 2010 and extreme rainfall events in 2007 and 2010 -therefore SOC concentration appears robust. However, we found significant relationships between erosion and deposition patterns (as quantified using 137Cs) and SOC for both catchments again demonstrating a strong geomorphic relationship. Vegetation across the catchments was assessed using remote sensing (Landsat and MODIS). Vegetation patterns were temporally consistent with above ground biomass increasing with elevation. SOC could be predicted using both these low and high resolution remote sensing platforms. Results indicate that, although moderate resolution (250 m) allows for reasonable prediction of the spatial distribution of SOC, the higher resolution (30 m) improved the strength of the SOC-NDVI relationship. The relationship between SOC and 137Cs, as a surrogate for the erosion and deposition of SOC, suggested that sediment transport and deposition influences the distribution of SOC within the catchment. The findings demonstrate that over the large catchment scale and at the decadal time scale that SOC is relatively constant and can largely be predicted by topography.

  18. Climate warming can accelerate carbon fluxes without changing soil carbon stocks

    Science.gov (United States)

    Ziegler, Susan E.; Benner, Ronald; Billings, Sharon A.; Edwards, Kate A.; Philben, Michael; Zhu, Xinbiao; Laganière, Jerome

    2017-02-01

    Climate warming enhances multiple ecosystem C fluxes, but the net impact of changing C fluxes on soil organic carbon (SOC) stocks over decadal to centennial time scales remains unclear. We investigated the effects of climate on C fluxes and soil C stocks using space-for-time substitution along a boreal forest climate gradient encompassing spatially replicated sites at each of three latitudes. All regions had similar SOC concentrations and stocks (5.6 to 6.7 kg C m-2). The three lowest latitude forests exhibited the highest productivity across the transect, with tree biomass:age ratios and litterfall rates 300% and 125% higher than those in the highest latitude forests, respectively. Likewise, higher soil respiration rates ( 55%) and dissolved organic C fluxes ( 300%) were observed in the lowest latitude forests compared to those in the highest latitude forests. The mid-latitude forests exhibited intermediate values for these indices and fluxes. The mean radiocarbon content (∆14C) of mineral-associated SOC (+9.6 ‰) was highest in the lowest latitude forests, indicating a more rapid turnover of soil C compared to the mid- and highest latitude soils (∆14C of -35 and -30 ‰, respectively). Indicators of the extent of soil organic matter decomposition, including C:N, δ13C, and amino acid and alkyl-C:O-alkyl-C indices, revealed highly decomposed material across all regions. These data indicate that the lowest latitude forests experience accelerated C fluxes that maintain relatively young but highly decomposed SOC. Collectively, these observations of within-biome soil C responses to climate demonstrate that the enhanced rates of SOC loss that typically occur with warming can be balanced by enhanced rates of C inputs.

  19. Carbonate precipitation in artificial soils as a sink for atmospheric carbon dioxide

    International Nuclear Information System (INIS)

    Renforth, P.; Manning, D.A.C.; Lopez-Capel, E.

    2009-01-01

    Turnover of C in soils is the dominant flux in the global C cycle and is responsible for transporting 20 times the quantity of anthropogenic emissions each year. This paper investigates the potential for soils to be modified with Ca-rich materials (e.g. demolition waste or basic slag) to capture some of the transferred C as geologically stable CaCO 3 . To test this principal, artificial soil known to contain Ca-rich minerals (Ca silicates and portlandite) was analysed from two sites across NE England, UK. The results demonstrate an average C content of 30 ± 15.3 Kg C m -2 stored as CaCO 3 , which is three times the expected organic C content and that it has accumulated at a rate of 25 ± 12.8 t C ha -1 a -1 since 1996. Isotopic analysis of the carbonates gave values between -6.4 per mille and -27.5 per mille for δ 13 C and -3.92 per mille and -20.89 per mille for δ 18 O, respectively (against V-PDB), which suggests that a combination of carbonate formation mechanisms are operating including the hydroxylation of gaseous CO 2 in solution, and the sequestration of degraded organic C with minor remobilisation/precipitation of lithogenic carbonates. This study implies that construction/development sites may be designed with a C capture function to sequester atmospheric C into the soil matrix with a maximum global potential of 290 Mt C a -1 .

  20. Characteristics of soil stability and carbon sequestration under water storage and drainage model

    Science.gov (United States)

    Li, J.; Han, J. C.; Chen, C.; Yang, J. J.

    2017-07-01

    This research was conducted to investigate the influence of saline alkali soil on soil physical properties, stability and organic carbon storage under water storage and drainage, and to provide scientific basis for improving soil quality in Fuping County of Shaanxi Province, China. Saline alkali soil model test was conducted and the process was assessed with two different methods: i) traditional drainage and ecological water storage, measure and analyze 0-30 cm soil bulk density, porosity, field water capacity, mean mass diameter (MWD), geological mean diameter (GMD), stability of water stable aggregate (WASR), aggregate destruction rate (PAD), fractal dimension (D) and; ii) organic carbon storage, comprehensively analyze the relationship between stability index and soil organic carbon. The results show that: (1) compared with traditional drainage treatment, water treatment may effectively reduce the soil bulk density by 1.3%-4.2%, and improve soil porosity and field capacity at the same time; (2) under dry and wet screen treatment, soil stability, the water storing treatment is higher than the drainage treatment. Performance trend of soil MWD and GMD increases with the increase of soil depth. The stability of soil water stable aggregates increased 14.5%-53.4%. The average aggregate destruction rate was 3.2% lower than that of the drainage treatment and the difference is obvious (Pfractal dimension and soil organic carbon storage. The correlation coefficient is, respectively, R2=0.86 and R2=0.94, and the difference is obvious (P<0.05). To sum up, the water storage treatment can effectively improve the soil quality, improve soil stability and soil organic carbon storage, which can be a good control of saline alkali soil.

  1. Limited opportunities for management-induced soil carbon storage in New South Wales, Australia.

    Science.gov (United States)

    Wilson, Brian; Lonergan, Vanessa

    2013-04-01

    Soil management has been promoted internationally and in Australia as a means of storing additional soil carbon to offset greenhouse gas emissions (GHG) elsewhere. Despite considerable investment in research in Australia, difficulties with reliable detection and estimation of soil carbon change remain as significant barriers to soil carbon accounting and trading. Here we present examples from an extensive dataset across the diverse production landscapes of New South Wales, Australia generated from both the NSW Statewide Soil Monitoring Program and the National Soil Carbon Research Program. Issues relating to climate, spatial variability, historical and contemporary land-management are highlighted to illustrate the challenges of detecting and estimating management-induced soil carbon change. We further demonstrate that, where it is possible to detect soil carbon change resulting from agricultural management, the quantities stored are unlikely to make a significant contribution to reductions in net greenhouse gas emissions. Historical factors and non-agricultural land-use options are likely to provide more significant potential for long-term soil carbon storage in this environment.

  2. Assessment of Soil Organic Carbon Stock of Temperate Coniferous Forests in Northern Kashmir

    Directory of Open Access Journals (Sweden)

    Davood A. Dar

    2015-02-01

    Full Text Available  Soil organic carbon (SOC estimation in temperate forests of the Himalaya is important to estimate their contribution to regional, national and global carbon stocks. Physico chemical properties of soil were quantified to assess soil organic carbon density (SOC and SOC CO2 mitigation density at two soil depths (0-10 and 10-20 cms under temperate forest in the Northern region of Kashmir Himalayas India. The results indicate that conductance, moisture content, organic carbon and organic matter were significantly higher while as pH and bulk density were lower at Gulmarg forest site. SOC % was ranging from 2.31± 0.96 at Gulmarg meadow site to 2.31 ± 0.26 in Gulmarg forest site. SOC stocks in these temperate forests were from 36.39 ±15.40 to 50.09 ± 15.51 Mg C ha-1. The present study reveals that natural vegetation is the main contributor of soil quality as it maintained the soil organic carbon stock. In addition, organic matter is an important indicator of soil quality and environmental parameters such as soil moisture and soil biological activity change soil carbon sequestration potential in temperate forest ecosystems.DOI: http://dx.doi.org/10.3126/ije.v4i1.12186International Journal of Environment Volume-4, Issue-1, Dec-Feb 2014/15; page: 161-178

  3. Comparing soil organic carbon dynamics in plantation and secondary forest in wet tropics in Puerto Rico

    Science.gov (United States)

    LI YIQING; MING XU; ZOU XIAOMING; PEIJUN SHI§; YAOQI ZHANG

    2005-01-01

    We compared the soil carbon dynamics between a pine plantation and a secondary forest, both of which originated from the same farmland abandoned in 1976 with the same cropping history and soil conditions, in the wet tropics in Puerto Rico from July 1996 to June 1997. We found that the secondary forest accumulated the heavy-fraction organic carbon (HF-OC) measured by...

  4. Soil Carbon Accumulation and CO2 Flux in Experimental Restoration Plots, Southern Iceland: Comparing Soil Treatment Strategies

    Directory of Open Access Journals (Sweden)

    Lawrence H. Tanner

    2015-01-01

    Full Text Available Experimental plots were established on severely eroded land surfaces in Iceland in 1999 to study the rates and limits of soil carbon sequestration during restoration and succession. The carbon content in the upper 10 cm of soils increased substantially during the initial eight years in all plots for which the treatments included both fertilizer and seeding with grasses, concomitant with the increase in vegetative cover. In the following five years, however, the soil carbon accumulation rates declined to negligible for most treatments and the carbon content in soils mainly remained relatively constant. We suggest that burial of vegetated surfaces by aeolian drift and nutrient limitation inhibited productivity and carbon sequestration in most plots. Only plots seeded with lupine demonstrated continued long-term soil carbon accumulation and soil CO2 flux rates significantly higher than background levels. This demonstrates that lupine was the sole treatment that resulted in vegetation capable of sustained growth independent of nutrient availability and resistant to disruption by aeolian processes.

  5. Effects of 24 Years of Conservation Tillage Systems on Soil Organic Carbon and Soil Productivity

    Directory of Open Access Journals (Sweden)

    Kenneth R. Olson

    2013-01-01

    Full Text Available The 24-year study was conducted in southern Illinois (USA on land similar to that being removed from Conservation Reserve Program (CRP to evaluate the effects of conservation tillage systems on: (1 amount and rates of soil organic carbon (SOC storage and retention, (2 the long-term corn and soybean yields, and (3 maintenance and restoration of soil productivity of previously eroded soils. The no-till (NT plots did store and retain 7.8 Mg C ha−1 more and chisel plow (CP −1.6 Mg C ha−1 less SOC in the soil than moldboard plow (MP during the 24 years. However, no SOC sequestration occurred in the sloping and eroding NT, CP, and MP plots since the SOC level of the plot area was greater at the start of the experiment than at the end. The NT plots actually lost a total of −1.2 Mg C ha−1, the CP lost −9.9 Mg C ha−1, and the MP lost −8.2 Mg C ha−1 during the 24-year study. The long-term productivity of NT compared favorably with that of MP and CP systems.

  6. [Changes in soil organic carbon and soil microbial functional diversity of Carya cathayensis plantations under intensive managements].

    Science.gov (United States)

    Wu, Jia-Sen; Qian, Jin-Fang; Tong, Zhi-Peng; Huang, Jian-Qin; Zhao, Ke-Li

    2014-09-01

    The change characteristics of soil organic carbon and microbial function diversity in Chinese hickory Carya cathayensis stands with different intensive-management durations (5, 10, 15 and 20 years) were studied. The results showed that soil total organic carbon (TOC), microbial biomass carbon (MBC), water-soluble organic carbon (WSOC) decreased significantly, while the stability of soil C pool increased significantly after the conversion from evergreen and deciduous broadleaf forest to intensively-managed forest (IMF). TOC, MBC and WSOC in the hickory forest soil decreased by 28.4%, 34.1% and 53.3% with 5-year intensive management, and by 38.6%, 48.9% and 64.1% with 20-year intensive management, respectively. The proportions of carboxyl C, phenolic C and aromatic C in the hickory forest soil all increased significantly, and the aromaticity of soil organic C increased by 23.0%. Soil microbial functional diversity decreased greatly af- ter intensive management of Chinese hickory forest. Significant differences in average well color development (AWCD) were found between the 0- and 5-year treatments and the 10-, 15- and 20- year treatments. The microbial diversity indexes (H) and evenness indexes (E) in the 0- and 5-year treatments were much greater than in the 10- and 20-year treatments. Correlation analysis showed that there were significant correlations among soil TOC, WSOC, MBC, AWCD, H and E.

  7. Accounting for Carbon Stocks in Soils and Measuring GHGs Emission Fluxes from Soils: Do We Have the Necessary Standards?

    Directory of Open Access Journals (Sweden)

    Antonio Bispo

    2017-07-01

    Full Text Available Soil is a key compartment for climate regulation as a source of greenhouse gases (GHGs emissions and as a sink of carbon. Thus, soil carbon sequestration strategies should be considered alongside reduction strategies for other greenhouse gas emissions. Taking this into account, several international and European policies on climate change are now acknowledging the importance of soils, which means that proper, comparable and reliable information is needed to report on carbon stocks and GHGs emissions from soil. It also implies a need for consensus on the adoption and verification of mitigation options that soil can provide. Where consensus is a key aspect, formal standards and guidelines come into play. This paper describes the existing ISO soil quality standards that can be used in this context, and calls for new ones to be developed through (international collaboration. Available standards cover the relevant basic soil parameters including carbon and nitrogen content but do not yet consider the dynamics of those elements. Such methods have to be developed together with guidelines consistent with the scale to be investigated and the specific use of the collected data. We argue that this standardization strategy will improve the reliability of the reporting procedures and results of the different climate models that rely on soil quality data.

  8. Soil fauna and organic amendment interactions affect soil carbon and crop performance in semi-arid West Africa

    NARCIS (Netherlands)

    Ouédraogo, E.; Brussaard, L.; Stroosnijder, L.

    2007-01-01

    A field experiment was conducted at Kaibo in southern Burkina Faso on an Eutric Cambisol during the 2000 rainy season to assess the interaction of organic amendment quality and soil fauna, affecting soil organic carbon and sorghum ( Sorghum bicolor L. Moench) performance. Plots were treated with the

  9. Carbon allocation and carbon isotope fluxes in the plant-soil-atmosphere continuum: a review

    Directory of Open Access Journals (Sweden)

    N. Brüggemann

    2011-11-01

    Full Text Available The terrestrial carbon (C cycle has received increasing interest over the past few decades, however, there is still a lack of understanding of the fate of newly assimilated C allocated within plants and to the soil, stored within ecosystems and lost to the atmosphere. Stable carbon isotope studies can give novel insights into these issues. In this review we provide an overview of an emerging picture of plant-soil-atmosphere C fluxes, as based on C isotope studies, and identify processes determining related C isotope signatures. The first part of the review focuses on isotopic fractionation processes within plants during and after photosynthesis. The second major part elaborates on plant-internal and plant-rhizosphere C allocation patterns at different time scales (diel, seasonal, interannual, including the speed of C transfer and time lags in the coupling of assimilation and respiration, as well as the magnitude and controls of plant-soil C allocation and respiratory fluxes. Plant responses to changing environmental conditions, the functional relationship between the physiological and phenological status of plants and C transfer, and interactions between C, water and nutrient dynamics are discussed. The role of the C counterflow from the rhizosphere to the aboveground parts of the plants, e.g. via CO2 dissolved in the xylem water or as xylem-transported sugars, is highlighted. The third part is centered around belowground C turnover, focusing especially on above- and belowground litter inputs, soil organic matter formation and turnover, production and loss of dissolved organic C, soil respiration and CO2 fixation by soil microbes. Furthermore, plant controls on microbial communities and activity via exudates and litter production as well as microbial community effects on C mineralization are reviewed. A further part of the paper is dedicated to physical interactions between soil CO2 and the soil matrix, such as

  10. Continuous soil carbon storage of old permanent pastures in Amazonia.

    Science.gov (United States)

    Stahl, Clément; Fontaine, Sébastien; Klumpp, Katja; Picon-Cochard, Catherine; Grise, Marcia Mascarenhas; Dezécache, Camille; Ponchant, Lise; Freycon, Vincent; Blanc, Lilian; Bonal, Damien; Burban, Benoit; Soussana, Jean-François; Blanfort, Vincent

    2017-08-01

    Amazonian forests continuously accumulate carbon (C) in biomass and in soil, representing a carbon sink of 0.42-0.65 GtC yr -1 . In recent decades, more than 15% of Amazonian forests have been converted into pastures, resulting in net C emissions (~200 tC ha -1 ) due to biomass burning and litter mineralization in the first years after deforestation. However, little is known about the capacity of tropical pastures to restore a C sink. Our study shows in French Amazonia that the C storage observed in native forest can be partly restored in old (≥24 year) tropical pastures managed with a low stocking rate (±1 LSU ha -1 ) and without the use of fire since their establishment. A unique combination of a large chronosequence study and eddy covariance measurements showed that pastures stored between -1.27 ± 0.37 and -5.31 ± 2.08 tC ha -1  yr -1 while the nearby native forest stored -3.31 ± 0.44 tC ha -1  yr -1 . This carbon is mainly sequestered in the humus of deep soil layers (20-100 cm), whereas no C storage was observed in the 0- to 20-cm layer. C storage in C4 tropical pasture is associated with the installation and development of C3 species, which increase either the input of N to the ecosystem or the C:N ratio of soil organic matter. Efforts to curb deforestation remain an obvious priority to preserve forest C stocks and biodiversity. However, our results show that if sustainable management is applied in tropical pastures coming from deforestation (avoiding fires and overgrazing, using a grazing rotation plan and a mixture of C3 and C4 species), they can ensure a continuous C storage, thereby adding to the current C sink of Amazonian forests. © 2016 John Wiley & Sons Ltd.

  11. Terrestrial Carbon Sequestration: Analysis of Terrestrial Carbon Sequestration at Three Contaminated Sites Remediated and Revitalized with Soil Amendments

    Science.gov (United States)

    This paper provides EPA's analysis of the data to determine carbon sequestration rates at three diverse sites that differ in geography/location, weather, soil properties, type of contamination, and age.

  12. Soil Organic Carbon (SOC) distribution in two differents soil types (Podzol and Andosol) under natural forest cover.

    Science.gov (United States)

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

    2017-04-01

    Andosols are young soils that shall know a successive evolution towards pedological types where the dominant pedogenetic processes are more evident. Vegetation and climate influence Andosols evolution to other order of soils. In cold and wet climates or on acid vulcanite under heavy leaching young Andosols could change into Podzols (Van Breemn and Buurman, 1998). Were investigated a Podzol soil (World References Base, 2014) at Zoniën (Belgium), were and an Andosol soil (World References Base, 2014) at Lago Laceno (Avellino, Italy). This study shows the data on the SOC (Soil Organic Carbon) fractionation in two profiles from two natural pine forest soils. Together with the conventional activities of sampling and analysis of soil profile were examined surveys meant to fractionation and characterization of SOC, in particular: Total Organic Carbon (TOC) and Total Extractable Carbon (TEC) soil contents were determined by Italian official method of soil analysis (Mi.P.A.F. (2000)). Different soil C fractions were also determined: Humic Acid Carbon (HAC), Fulvic Acid Carbon (FAC), Not Humic Carbon (NHC) and Humin Carbon (Huc) fractions were obtained by difference. In the whole profile, therefore, were also assayed cellulose and lignin contents. The aim of this work was to compare the distribution of different soil organic components in a podzol and a soil with andic properties. The data show great similarity, among the selected profiles, in the organic components distribution estudied. References: - Mi.P.A.F. - Ministero per le Politiche Agricole e Forestali - Osservatorio Nazionale Pedologico e per la Qualità del Suolo (2000): Metodi Ufficiali di Analisi Chimica del Suolo. In: Franco Angeli (Editor), Collana di metodi analitici per l'agricoltura diretta da Paolo Sequi, n. 1124.2, Milano, Italy. - Van Breemn N. and Buurman P. (1998) Chapter 12 Formation of Andisols. In: Soil formation. Kluwer Ed., Wageningen, The Netherlands, 271-289. -Ussiri D.A.N., Johnson C

  13. An approach to include soil carbon changes in life cycle assessments

    DEFF Research Database (Denmark)

    Petersen, Bjorn Molt; Knudsen, Marie Trydeman; Hermansen, John Erik

    2013-01-01

    Globally, soil carbon sequestration is expected to hold a major potential to mitigate agricultural greenhouse gas emissions. However, the majority of life cycle assessments (LCA) of agricultural products have not included possible changes in soil carbon sequestration. In the present study, a method...... production in China. The suggested approach considers the time of the soil CO2 emissions for the LCA by including the Bern Carbon Cycle Model. Time perspectives of 20,100 and 200 years are used and a soil depth of 0-100 cm is considered. The application of the suggested method showed that the results were...... to estimate carbon sequestration to be included in LCA is suggested and applied to two examples where the inclusion of carbon sequestration is especially relevant: 1) Bioenergy: removal of straw from a Danish soil for energy purposes and 2) Organic versus conventional farming: comparative study of soybean...

  14. Grasslands and Croplands Have Different Microbial Biomass Carbon Levels per Unit of Soil Organic Carbon

    Directory of Open Access Journals (Sweden)

    Terence P. McGonigle

    2017-07-01

    Full Text Available Primarily using cropped systems, previous studies have reported a positive linear relationship between microbial biomass carbon (MBC and soil organic carbon (SOC. We conducted a meta-analysis to explore this relationship separately for grasslands and croplands using available literature. Studies were limited to those using fumigation–extraction for MBC for field samples. Trials were noted separately where records were distinct in space or time. Grasslands were naturally occurring, restored, or seeded. Cropping systems were typical of the temperate zone. MBC had a positive linear response to increasing SOC that was significant in both grasslands (p < 0.001; r2 = 0.76 and croplands (p < 0.001; r2 = 0.48. However, MBC increased 2.5-fold more steeply per unit of increasing SOC for grassland soils, as compared to the corresponding response in cropland soils. Expressing MBC as a proportion of SOC across the regression overall, slopes corresponded to 2.7% for grasslands and 1.1% for croplands. The slope of the linear relationship for grasslands was significantly (p = 0.0013 steeper than for croplands. The difference between the two systems is possibly caused by a greater proportion of SOC in grasslands being active rather than passive, relative to that in croplands, with that active fraction promoting the formation of MBC.

  15. Digital Mapping of Soil Organic Carbon Contents and Stocks in Denmark

    DEFF Research Database (Denmark)

    Adhikari, Kabindra; Hartemink, Alfred E.; Minasny, Budiman

    2014-01-01

    Estimation of carbon contents and stocks are important for carbon sequestration, greenhouse gas emissions and national carbon balance inventories. For Denmark, we modeled the vertical distribution of soil organic carbon (SOC) and bulk density, and mapped its spatial distribution at five standard...... soil depth intervals (025, 5215, 15230, 30260 and 602 100 cm) using 18 environmental variables as predictors. SOC distribution was influenced by precipitation, land use, soil type, wetland, elevation, wetness index, and multi-resolution index of valley bottom flatness. The highest average SOC content...

  16. Soil carbon stock change in the forests of Denmark between 1990 and 2008

    DEFF Research Database (Denmark)

    Callesen, Ingeborg; Stupak, Inge; Georgiadis, Petros

    2015-01-01

    Soils of the forests in Denmark were sampled in permanent plots in 1990 (t1) and resampled (N = 124) in 2007–9 (t2). The soils were classified according to the carbon concentration in the uppermost mineral soil horizon (0–25 cm) at t1, and according to subsoil texture and presence or absence of C...

  17. Soil classification and carbon storage in cacao agroforestry farming systems of Bahia, Brazil

    Science.gov (United States)

    Information concerning the classification of soils and their properties under cacao agroforestry systems of the Atlantic rain forest biome region in the Southeast of Bahia Brazil is largely unknown. Soil and climatic conditions in this region are favorable for high soil carbon storage. This study is...

  18. Negative priming of native soil organic carbon mineralization by oilseed biochars of contrasting quality

    NARCIS (Netherlands)

    Francischinelli Rittl, T.; Novotny, E.H.; Baliero, F.C.; Hoffland, E.; Alves, B.J.R.; Kuijper, T.W.M.

    2015-01-01

    Oilseed-derived biochar, a by-product of pyrolysis for biodiesel production, is richer in aliphatic compounds than the commonly studied wood-derived biochar, affecting both its mineralization in soil and its interaction with native soil organic carbon (nSOC). Here, we investigated the soil C

  19. Dynamics of soil dissolved organic carbon pools reveal both hydrophobic and hydrophilic compounds sustain microbial respiration

    NARCIS (Netherlands)

    Straathof, A.L.; Chincarini, R.; Comans, R.N.J.; Hoffland, E.

    2014-01-01

    The quality of dissolved organic carbon (DOC) released from soil organic amendments may influence soil microbial activity and the quality of the soil's DOC pools. Measurements of total DOC are often considered in relation to microbial activity levels but here we propose that quantification of DOC

  20. Carbon and nitrogen stocks in the soils of Central and Eastern Europe

    NARCIS (Netherlands)

    Batjes, N.H.

    2002-01-01

    Soil organic carbon and total nitrogen stocks are presented for Central and Eastern Europe. The study uses the soil geographic and attribute data held in a 1:2 500 000 scale Soil and Terrain (SOTER) database, covering Belarus, Bulgaria, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Moldova,

  1. Soil carbon inventories and d 13C along a moisture gradient in Botswana

    NARCIS (Netherlands)

    Bird, M.I.; Veenendaal, E.M.; Lloyd, J.

    2004-01-01

    We present a study of soil organic carbon (SOC) inventories and d 13C values for 625 soil cores collected from well-drained, coarse-textured soils in eight areas along a 1000 km moisture gradient from Southern Botswana, north into southern Zambia. The spatial distribution of trees and grass in the

  2. Soil carbon sequestration and changes in fungal and bacterial biomass following incorporation of forest residues

    Science.gov (United States)

    Matt D. Busse; Felipe G. Sanchez; Alice W. Ratcliff; John R. Butnor; Emily A. Carter; Robert F. Powers

    2009-01-01

    Sequestering carbon (C) in forest soils can benefit site fertility and help offset greenhouse gas emissions. However, identifying soil conditions and forest management practices which best promote C accumulation remains a challenging task. We tested whether soil incorporation of masticated woody residues alters short-term C storage at forested sites in western and...

  3. The effect of soil carbon on symbiotic nitrogen fixation and symbiotic ...

    African Journals Online (AJOL)

    Soil organic carbon (SOC) is the main attribute of high-quality soil. The amount of nitrogen fixed by Rhizobium symbiotically with Trifolium repens (white clover) is ultimately determined by the quality of the soil environment. The effect of SOC on the total number of symbiotic and saprophytic rhizobia was determined.

  4. Burrowing herbivores alter soil carbon and nitrogen dynamics in a semi-arid ecosystem, Argentina

    Science.gov (United States)

    Kenneth L. Clark; Lyn C. Branch; Jose L. Hierro; Diego. Villarreal

    2016-01-01

    Activities of burrowing herbivores, including movement of soil and litter and deposition of waste material, can alter the distribution of labile carbon (C) and nitrogen (N) in soil, affecting spatial patterning of nutrient dynamics in ecosystems where they are abundant. Their role in ecosystem processes in surface soil has been studied extensively, but effects of...

  5. Carbon black retention in saturated natural soils: Effects of flow conditions, soil surface roughness and soil organic matter.

    Science.gov (United States)

    Lohwacharin, J; Takizawa, S; Punyapalakul, P

    2015-10-01

    We evaluated factors affecting the transport, retention, and re-entrainment of carbon black nanoparticles (nCBs) in two saturated natural soils under different flow conditions and input concentrations using the two-site transport model and Kelvin probe force microscopy (KPFM). Soil organic matter (SOM) was found to create unfavorable conditions for the retention. Despite an increased flow velocity, the relative stability of the estimated maximum retention capacity in soils may suggest that flow-induced shear stress forces were insufficient to detach nCB. The KPFM observation revealed that nCBs were retained at the grain boundary and on surface roughness, which brought about substantial discrepancy between theoretically-derived attachment efficiency factors and the ones obtained by the experiments using the two-site transport model. Thus, decreasing ionic strength and increasing solution pH caused re-entrainment of only a small fraction of retained nCB in the soil columns. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Distribution of ancient carbon in buried soils in an eroding loess landscape

    Science.gov (United States)

    Szymanski, L. M.; Mason, J. A.; De Graaff, M. A.; Berhe, A. A.; Marin-Spiotta, E.

    2017-12-01

    Understanding the processes that contribute to the accumulation and loss of carbon in soils and the implications for land management is vital for mitigating climate change. Buried soils or paleosols that represent former surface horizons can store more organic carbon than mineral horizons at equivalent depths due to burial restricting microbial decomposition. The presence of buried soils defies modeled expectations of exponential declines in carbon concentrations with depth, especially in locations where successive depositional events lead to multiple buried soil layers. Buried soils are found in a diversity of depositional environments across latitudes and without accounting for their presence can lead to underestimates of regional carbon reservoirs. Here we present data on the spatial distribution of carbon in a paleosol loess sequence in Nebraska, focusing on one prominent paleosol, the Brady soil. The Brady soil has been identified throughout the Central Great Plains and began developing at the end of the Pleistocene and was subsequently buried by loess in the early Holocene (Mason et al. 2003). Preliminary analyses of the Brady soil at its deepest, 6-m below the surface, reveal large differences in the composition and degree of decomposition of organic matter from the modern soil. We sampled along burial and erosional transects to characterize spatial variability in the depth of Brady soil from the modern landscape surface and to determine how these differences may alter the amount and composition of organic carbon. A more accurate determination of the spatial extent and heterogeneity of buried soil carbon will improve regional estimates of carbon reservoirs. This assessment of its variability across the landscape will inform future planned work on the vulnerability of ancient carbon to disturbance.

  7. Effects of wetland recovery on soil labile carbon and nitrogen in the Sanjiang Plain.

    Science.gov (United States)

    Huang, Jingyu; Song, Changchun; Nkrumah, Philip Nti

    2013-07-01

    Soil management significantly affects the soil labile organic factors. Understanding carbon and nitrogen dynamics is extremely helpful in conducting research on active carbon and nitrogen components for different kinds of soil management. In this paper, we examined the changes in microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), dissolved organic carbon (DOC), and dissolved organic nitrogen (DON) to assess the effect and mechanisms of land types, organic input, soil respiration, microbial species, and vegetation recovery under Deyeuxia angustifolia freshwater marshes (DAMs) and recovered freshwater marsh (RFM) in the Sanjiang Plain, Northeast China. Identifying the relationship among the dynamics of labile carbon, nitrogen, and soil qualification mechanism using different land management practices is therefore important. Cultivation and land use affect intensely the DOC, DON, MBC, and MBN in the soil. After DAM soil tillage, the DOC, DON, MBC, and MBN at the surface of the agricultural soil layer declined significantly. In contrast, their recovery was significant in the RFM surface soil. A long time was needed for the concentration of cultivated soil total organic carbon and total nitrogen to be restored to the wetland level. The labile carbon and nitrogen fractions can reach a level similar to that of the wetland within a short time. Typical wetland ecosystem signs, such as vegetation, microbes, and animals, can be recovered by soil labile carbon and nitrogen fraction restoration. In this paper, the D. angustifolia biomass attained natural wetland level after 8 years, indicating that wetland soil labile fractions can support wetland eco-function in a short period of time (4 to 8 years) for reconstructed wetland under suitable environmental conditions.

  8. Technologies for increasing carbon storage in soil to mitigate climate change

    OpenAIRE

    Whitmore, A.P.; Kirk, G.J.D.; Rawlins, B.G.

    2015-01-01

    Means to enhance storage of carbon in soil or avoid its loss from soil are discussed and examined from the viewpoint of policy. In particular, technologies that have until now received little attention are assessed. The main means by which soil carbon might be increased are first listed. These are the following: (i) increasing the rate of input of organic matter; (ii) decreasing the rate of its decomposition by biological or chemical means; (iii) increasing the rate of its stabilization by ph...

  9. Aggregate formation and soil carbon sequestration by earthworms at the ORNL FACE experiment

    Science.gov (United States)

    Sanchez-de Leon, Y.; Gonzalez-Meler, M. A.; Lugo-Perez, J.; Wise, D. H.; Jastrow, J. D.

    2012-12-01

    Earthworms have an important role in soil carbon sequestration, but their contribution to carbon sequestration in soils exposed to elevated atmospheric CO2 concentrations has been largely overlooked. Previous studies at the Oak Ridge National Laboratory Free Air CO2 Experiment (ORNL FACE) site showed that the formation of soil aggregates is a key mechanism for soil carbon sequestration. We did a microcosm experiment to quantify earthworm-mediated aggregate formation and compare between two earthworm species with different feeding habits (endogeic vs. epi-edogeic). In addition, we wanted to identify the carbon source (soil, leaf litter or root litter) within aggregates formed by earthworms. We used 13C-depleted soil and 15N-enriched sweetgum (Liquidambar styraciflua) leaf and root litter collected from the ORNL FACE site to assess soil aggregate formation of the native, endogeic earthworm Diplocardia sp. and European, epi-endogeic earthworm Lumbricus rubellus. Both earthworm species are present at the ORNL FACE site. We crushed, sieved ( 250 μm) were higher in treatments with earthworms (III and IV) than in treatments without earthworms (I and II) (p = 0.02). Within macroaggregates, most of the carbon was soil-derived. Leaf and root-derived carbon was found in treatment IV only. Our results suggest that earthworms at the ORNL FACE site directly contribute to the formation of soil aggregates, thus contributing to soil carbon sequestration. Carbon source within macroaggregates correspond with earthworm feeding habits, with endogeic earthworms (Diplocardia sp.) feeding mostly on mineral soil and epi-endogeic earthworm (L. rubellus) feeding on both plant residues and soil organic matter.

  10. Soil carbon sequestration and climate change in semi-arid Sudan

    OpenAIRE

    Ardö, Jonas

    2015-01-01

    Climate change poses risk for natural and human systems in Africa. Increasing temperatures and changes in precipitation patterns is likely to affect agriculture, pastoralism and forestry. Mitigation of increasing atmospheric concentration of CO2 through soil carbon sequestration in semi-arid ecosystems may be beneficial to soil properties and cultivation. This paper describes and discusses soil carbon sequestration in relation to climate change in semi-arid regions, with special attention to ...

  11. Experimental Evidence that Hemlock Mortality Enhances Carbon Stabilization in Southern Appalachian Forest Soils

    Science.gov (United States)

    Fraterrigo, J.; Ream, K.; Knoepp, J.

    2017-12-01

    Forest insects and pathogens (FIPs) can cause uncertain changes in forest carbon balance, potentially influencing global atmospheric carbon dioxide (CO2) concentrations. We quantified the effects of hemlock (Tsuga canadensis L. Carr.) mortality on soil carbon fluxes and pools for a decade following either girdling or natural infestation by hemlock woolly adelgid (HWA; Adelges tsugae) to improve mechanistic understanding of soil carbon cycling response to FIPs. Although soil respiration (Rsoil) was similar among reference plots and plots with hemlock mortality, both girdled and HWA-infested plots had greater activities of β-glucosidase, a cellulose-hydrolyzing extracellular enzyme, and decreased O-horizon mass and fine root biomass from 2005 to 2013. During this period, total mineral soil carbon accumulated at a higher rate in disturbed plots than in reference plots in both the surface (0-10 cm) and subsurface (10-30 cm); increases were predominantly in the mineral-associated fraction of the soil organic matter. In contrast, particulate organic matter carbon accrued slowly in surface soils and declined in the subsurface of girdled plots. δ13C values of this fraction demonstrate that particulate organic matter carbon in the surface soil has become more microbially processed over time, suggesting enhanced decomposition of organic matter in this pool. Together, these findings indicate that hemlock mortality and subsequent forest regrowth has led to enhanced soil carbon stabilization in southern Appalachian forests through the translocation of carbon from detritus and particulate soil organic matter pools to the mineral-associated organic matter pool. These findings have implications for ecosystem management and modeling, demonstrating that forests may tolerate moderate disturbance without diminishing soil carbon storage when there is a compensatory growth response by non-host trees.

  12. Incorporating microbial dormancy dynamics into soil decomposition models to improve quantification of soil carbon dynamics of northern temperate forests

    Energy Technology Data Exchange (ETDEWEB)

    He, Yujie [Purdue Univ., West Lafayette, IN (United States). Dept. of Earth, Atmospheric, and Planetary Sciences; Yang, Jinyan [Univ. of Georgia, Athens, GA (United States). Warnell School of Forestry and Natural Resources; Northeast Forestry Univ., Harbin (China). Center for Ecological Research; Zhuang, Qianlai [Purdue Univ., West Lafayette, IN (United States). Dept. of Earth, Atmospheric, and Planetary Sciences; Purdue Univ., West Lafayette, IN (United States). Dept. of Agronomy; Harden, Jennifer W. [U.S. Geological Survey, Menlo Park, CA (United States); McGuire, Anthony D. [Alaska Cooperative Fish and Wildlife Research Unit, U.S. Geological Survey, Univ. of Alaska, Fairbanks, AK (United States). U.S. Geological Survey, Alaska Cooperative Fish and Wildlife Research Unit; Liu, Yaling [Purdue Univ., West Lafayette, IN (United States). Dept. of Earth, Atmospheric, and Planetary Sciences; Wang, Gangsheng [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Climate Change Science Inst. and Environmental Sciences Division; Gu, Lianhong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division

    2015-11-20

    Soil carbon dynamics of terrestrial ecosystems play a significant role in the global carbon cycle. Microbial-based decomposition models have seen much growth recently for quantifying this role, yet dormancy as a common strategy used by microorganisms has not usually been represented and tested in these models against field observations. Here in this study we developed an explicit microbial-enzyme decomposition model and examined model performance with and without representation of microbial dormancy at six temperate forest sites of different forest types. We then extrapolated the model to global temperate forest ecosystems to investigate biogeochemical controls on soil heterotrophic respiration and microbial dormancy dynamics at different temporal-spatial scales. The dormancy model consistently produced better match with field-observed heterotrophic soil CO2 efflux (RH) than the no dormancy model. Our regional modeling results further indicated that models with dormancy were able to produce more realistic magnitude of microbial biomass (<2% of soil organic carbon) and soil RH (7.5 ± 2.4 PgCyr-1). Spatial correlation analysis showed that soil organic carbon content was the dominating factor (correlation coefficient = 0.4-0.6) in the simulated spatial pattern of soil RH with both models. In contrast to strong temporal and local controls of soil temperature and moisture on microbial dormancy, our modeling results showed that soil carbon-to-nitrogen ratio (C:N) was a major regulating factor at regional scales (correlation coefficient = -0.43 to -0.58), indicating scale-dependent biogeochemical controls on microbial dynamics. Our findings suggest that incorporating microbial dormancy could improve the realism of microbial-based decomposition models and enhance the integration of soil experiments and mechanistically based modeling.

  13. The diversity of methoxyphenols released by pyrolysis-gas chromatography as predictor of soil carbon storage.

    Science.gov (United States)

    Jiménez-González, Marco A; Álvarez, Ana M; Carral, Pilar; González-Vila, Francisco J; Almendros, Gonzalo

    2017-07-28

    The variable extent to which environmental factors are involved in soil carbon storage is currently a subject of controversy. In fact, justifying why some soils accumulate more organic matter than others is not trivial. Some abiotic factors such as organo-mineral associations have classically been invoked as the main drivers for soil C stabilization. However, in this research indirect evidences based on correlations between soil C storage and compositional descriptors of the soil organic matter are presented. It is assumed that the intrinsic structure of soil organic matter should have a bearing in the soil carbon storage. This is examined here by focusing on the methoxyphenols released by direct pyrolysis from a wide variety of topsoil samples from continental Mediterranean ecosystems from Spain with different properties and carbon content. Methoxyphenols are typical signature compounds presumptively informing on the occurrence and degree of alteration of lignin in soils. The methoxyphenol assemblages (12 major guaiacyl- and syringyl-type compounds) were analyzed by pyrolysis-gas chromatography-mass spectrometry. The Shannon-Wiener diversity index was chosen to describe the complexity of this phenolic signature. A series of exploratory statistical analyses (simple regression, partial least squares regression, multidimensional scaling) were applied to analyze the relationships existing between chemical and spectroscopic characteristics and the carbon content in the soils. These treatments coincided in pointing out that significant correlations exist between the progressive molecular diversity of the methoxyphenol assemblages and the concentration of organic carbon stored in the corresponding soils. This potential of the diversity in the phenolic signature as a surrogate index of the carbon storage in soils is tentatively interpreted as the accumulation of plant macromolecules altered into microbially reworked structures not readily recognized by soil enzymes. From

  14. Evaluation of Soil Quality Using Labile Organic Carbon and Carbon Management Indices in Agricultural Lands of Neyriz, Fars Province

    Directory of Open Access Journals (Sweden)

    Anahid Salmanpour

    2017-02-01

    Full Text Available Introduction: Soil organic matter is considered as an indicator of soil quality, because of its role on the stability of soil structure, water holding capacity, microbial activity, storage and release of nutrients. Although changes and trends of organic matter are assessed on the basis of organic carbon, it responds slowly to changes of soil management. Therefore, identifying sensitive components of organic carbon such as carbon labile lead to better understanding of the effect of land use change and soil management on soil quality. The main components of sustainable agriculture in arid and semi-arid regions are the amount of water; and soil and water salinity. Water deficit and irrigation with saline water are important limiting factors for cropping and result in adverse effects on soil properties and soil quality. Soil carbon changes is a function of addition of plant debris and removal of it from soil by its decomposition. If the amount of organic carbon significantly reduced due to the degradation of the soil physical and chemical properties and soil quality, agricultural production will face serious problems. To this end, this study was done to evaluate soil quality using soil labile carbon and soil carbon management indices in some agricultural lands of Neyriz area, Fars province, Iran. Materials and Methods: Five fields were selected in two regions, Dehfazel and Tal-e-mahtabi, consisted of irrigated wheat and barley with different amount of irrigation water and water salinity levels. Three farms were located in Dehfazel and two farms in Tal-e-Mahtabi region. In each farm, three points were randomly selected and soil samples were collected from 0-40 cm of the surface layer. Plant samples were taken from a 1x1 square meter and grain crop yield was calculated per hectare. Water samples were obtained in each region from the wells at the last irrigation. Physical and chemical characteristics of the soil and water samples were determined. Soil

  15. [Estimation of soil carbon sequestration potential in typical steppe of Inner Mongolia and associated uncertainty].

    Science.gov (United States)

    Wang, Wei; Wu, Jian-Guo; Han, Xing-Guo

    2012-01-01

    Based on the measurements in the enclosure and uncontrolled grazing plots in the typical steppe of Xilinguole, Inner Mongolia, this paper studied the soil carbon storage and carbon sequestration in the grasslands dominated by Leymus chinensis, Stipa grandis, and Stipa krylovii, respectively, and estimated the regional scale soil carbon sequestration potential in the heavily degraded grassland after restoration. At local scale, the annual soil carbon sequestration in the three grasslands all decreased with increasing year of enclosure. The soil organic carbon storage was significantly higher in the grasslands dominated by L. chinensis and Stipa grandis than in that dominated by Stipa krylovii, but the latter had much higher soil carbon sequestration potential, because of the greater loss of soil organic carbon during the degradation process due to overgrazing. At regional scale, the soil carbon sequestration potential at the depth of 0-20 cm varied from -0.03 x 10(4) to 3.71 x 10(4) kg C x a(-1), and the total carbon sequestration potential was 12.1 x 10(8) kg C x a(-1). Uncertainty analysis indicated that soil gravel content had less effect on the estimated carbon sequestration potential, but the estimation errors resulted from the spatial interpolation of climate data could be about +/- 4.7 x 10(9) kg C x a(-1). In the future, if the growth season precipitation in this region had an average variation of -3.2 mm x (10 a)(-1), the soil carbon sequestration potential would be de- creased by 1.07 x 10(8) kg C x (10 a)(-1).

  16. A review on soil carbon accumulation due to the management change of major Brazilian agricultural activities

    Directory of Open Access Journals (Sweden)

    N. La Scala Júnior

    Full Text Available Agricultural areas deal with enormous CO2 intake fluxes offering an opportunity for greenhouse effect mitigation. In this work we studied the potential of soil carbon sequestration due to the management conversion in major agricultural activities in Brazil. Data from several studies indicate that in soybean/maize, and related rotation systems, a significant soil carbon sequestration was observed over the year of conversion from conventional to no-till practices, with a mean rate of 0.41 Mg C ha-1 year-1. The same effect was observed in sugarcane fields, but with a much higher accumulation of carbon in soil stocks, when sugarcane fields are converted from burned to mechanised based harvest, where large amounts of sugarcane residues remain on the soil surface (1.8 Mg C ha-1 year-1. The higher sequestration potential of sugarcane crops, when compared to the others, has a direct relation to the primary production of this crop. Nevertheless, much of this mitigation potential of soil carbon accumulation in sugarcane fields is lost once areas are reformed, or intensive tillage is applied. Pasture lands have shown soil carbon depletion once natural areas are converted to livestock use, while integration of those areas with agriculture use has shown an improvement in soil carbon stocks. Those works have shown that the main crop systems of Brazil have a huge mitigation potential, especially in soil carbon form, being an opportunity for future mitigation strategies.

  17. A review on soil carbon accumulation due to the management change of major Brazilian agricultural activities.

    Science.gov (United States)

    La Scala, N; De Figueiredo, E B; Panosso, A R

    2012-08-01

    Agricultural areas deal with enormous CO2 intake fluxes offering an opportunity for greenhouse effect mitigation. In this work we studied the potential of soil carbon sequestration due to the management conversion in major agricultural activities in Brazil. Data from several studies indicate that in soybean/maize, and related rotation systems, a significant soil carbon sequestration was observed over the year of conversion from conventional to no-till practices, with a mean rate of 0.41 Mg C ha(-1) year(-1). The same effect was observed in sugarcane fields, but with a much higher accumulation of carbon in soil stocks, when sugarcane fields are converted from burned to mechanised based harvest, where large amounts of sugarcane residues remain on the soil surface (1.8 Mg C ha(-1) year(-1)). The higher sequestration potential of sugarcane crops, when compared to the others, has a direct relation to the primary production of this crop. Nevertheless, much of this mitigation potential of soil carbon accumulation in sugarcane fields is lost once areas are reformed, or intensive tillage is applied. Pasture lands have shown soil carbon depletion once natural areas are converted to livestock use, while integration of those areas with agriculture use has shown an improvement in soil carbon stocks. Those works have shown that the main crop systems of Brazil have a huge mitigation potential, especially in soil carbon form, being an opportunity for future mitigation strategies.

  18. Soil fluxes of carbonyl sulfide (COS), carbon monoxide, and carbon dioxide in a boreal forest in southern Finland

    NARCIS (Netherlands)

    Sun, Wu; Kooijmans, Linda M. J.; Maseyk, Kadmiel; Chen, Huilin; Mammarella, Ivan; Vesala, Timo; Levula, Janne; Keskinen, Helmi; Seibt, Ulli

    2018-01-01

    Soil is a major contributor to the biosphere-atmosphere exchange of carbonyl sulfide (COS) and carbon monoxide (CO). COS is a tracer with which to quantify terrestrial photosynthesis based on the coupled leaf uptake of COS and CO2, but such use requires separating soil COS flux, which is unrelated

  19. Impact of exotic earthworms on organic carbon sorption on mineral surfaces and soil carbon inventories in a northern hardwood forest

    Science.gov (United States)

    Amy Lyttle; Kyungsoo Yoo; Cindy Hale; Anthony Aufdenkampe; Stephen D. Sebestyen; Kathryn Resner; Alex. Blum

    2015-01-01

    Exotic earthworms are invading forests in North America where native earthworms have been absent since the last glaciation. These earthworms bioturbate soils and may enhance physical interactions between minerals and organic matter (OM), thus affecting mineral sorption of carbon (C) which may affect C cycling. We quantitatively show how OM-mineral sorption and soil C...

  20. How will Shrub Expansion Impact Soil Carbon Sequestration in Arctic Tundra?

    Science.gov (United States)

    Czimczik, C. I.; Holden, S. R.; He, Y.; Randerson, J. T.

    2015-12-01

    Multiple lines of evidence suggest that plant productivity, and especially shrub abundance, is increasing in the Arctic in response to climate change. This greening is substantiated by increases in the Normalized Difference Vegetation Index, repeat photography and field observations. The implications of a greener Arctic on carbon sequestration by tundra ecosystems remain poorly understood. Here, we explore existing datasets of plant productivity and soil carbon stocks to quantify how greening, and in particular an expansion of woody shrubs, may translate to the sequestration of carbon in arctic soils. As an estimate of carbon storage in arctic tundra soils, we used the Northern Circumpolar Soil Carbon Database v2. As estimates of tundra type and productivity, we used the Circumpolar Arctic Vegetation map as well as the MODIS and Landsat Vegetation Continuous Fields, and MODIS GPP/NPP (MOD17) products. Preliminary findings suggest that in graminoid tundra and erect-shrub tundra higher shrub abundance is associated with greater soil carbon stocks. However, this relationship between shrub abundance and soil carbon is not apparent in prostrate-shrub tundra, or when comparing across graminoid tundra, erect-shrub tundra and prostrate-shrub tundra. Uncertainties originate from the extreme spatial (vertical and horizontal) heterogeneity of organic matter distribution in cryoturbated soils, the fact that (some) permafrost carbon stocks, e.g. yedoma, reflect previous rather than current vegetative cover, and small sample sizes, esp. in the High Arctic. Using Vegetation Continuous Fields and MODIS GPP/NPP (MOD17), we develop quantitative trajectories of soil carbon storage as a function of shrub cover and plant productivity in the Arctic (>60°N). We then compare our greening-derived carbon sequestration estimates to projected losses of carbon from thawing permafrost. Our findings will reduce uncertainties in the magnitude and timing of the carbon-climate feedback from the

  1. 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

  2. Topographic Controls on Soil Carbon Distribution in Iowa Croplands, USA

    Science.gov (United States)

    McCarty, Greg; Li, Xia

    2017-04-01

    Topography is a key factor affecting soil organic carbon (SOC) redistribution (erosion or deposition) because it influences several hydrological indices including soil moisture dynamics, runoff velocity and acceleration, and flow divergence and convergence. In this study, we examined the relationship between 15 topographic metrics derived from Light Detection and Ranging (Lidar) data and SOC redistribution in agricultural fields. We adopted the fallout 137Cesium (137Cs) technique to estimate SOC redistribution rates across 560 sampling plots in Iowa. Then, using stepwise ordinarily least square regression (SOLSR) and stepwise principle component analysis (SPCA), topography-based SOC models were developed to simulate spatial patterns of SOC content and redistribution. Results suggested that erosion and deposition of topsoil SOC were regulated by topography with SOC gain in lowland areas and SOC loss in sloping areas. Topographic wetness index (TWI) and slope were the most influential variables controlling SOC content and redistribution. The topography-based models exhibited good performances in simulating SOC content and redistribution across two crop sites with intensive samplings. SPCA models had slightly lower coefficients of determination and Nash-Sutcliffe efficiency values compared to SOLSR models at the field scale. However, significantly SPCA outperformed SOLAR in predicting SOC redistribution patterns at the watershed scale. Results of this study suggest that the topography-based SPCA model was more robust for scaling up models to the watershed scale because SPCA models may better represent the landscapes and are less subject to over fitting. This work suggests an improved method to sample and characterize landscapes for better prediction of soil property distribution.

  3. Estimating soil organic carbon stocks and spatial patterns with statistical and GIS-based methods.

    Science.gov (United States)

    Zhi, Junjun; Jing, Changwei; Lin, Shengpan; Zhang, Cao; Liu, Qiankun; DeGloria, Stephen D; Wu, Jiaping

    2014-01-01

    Accurately quantifying soil organic carbon (SOC) is considered fundamental to studying soil quality, modeling the global carbon cycle, and assessing global climate change. This study evaluated the uncertainties caused by up-scaling of soil properties from the county scale to the provincial scale and from lower-level classification of Soil Species to Soil Group, using four methods: the mean, median, Soil Profile Statistics (SPS), and pedological professional knowledge based (PKB) methods. For the SPS method, SOC stock is calculated at the county scale by multiplying the mean SOC density value of each soil type in a county by its corresponding area. For the mean or median method, SOC density value of each soil type is calculated using provincial arithmetic mean or median. For the PKB method, SOC density value of each soil type is calculated at the county scale considering soil parent materials and spatial locations of all soil profiles. A newly constructed 1∶50,000 soil survey geographic database of Zhejiang Province, China, was used for evaluation. Results indicated that with soil classification levels up-scaling from Soil Species to Soil Group, the variation of estimated SOC stocks among different soil classification levels was obviously lower than that among different methods. The difference in the estimated SOC stocks among the four methods was lowest at the Soil Species level. The differences in SOC stocks among the mean, median, and PKB methods for different Soil Groups resulted from the differences in the procedure of aggregating soil profile properties to represent the attributes of one soil type. Compared with the other three estimation methods (i.e., the SPS, mean and median methods), the PKB method holds significant promise for characterizing spatial differences in SOC distribution because spatial locations of all soil profiles are considered during the aggregation procedure.

  4. Climate Impacts on Soil Carbon Processes along an Elevation Gradient in the Tropical Luquillo Experimental Forest

    Directory of Open Access Journals (Sweden)

    Dingfang Chen

    2017-03-01

    Full Text Available Tropical forests play an important role in regulating the global climate and the carbon cycle. With the changing temperature and moisture along the elevation gradient, the Luquillo Experimental Forest in Northeastern Puerto Rico provides a natural approach to understand tropical forest ecosystems under climate change. In this study, we conducted a soil translocation experiment along an elevation gradient with decreasing temperature but increasing moisture to study the impacts of climate change on soil organic carbon (SOC and soil respiration. As the results showed, both soil carbon and the respiration rate were impacted by microclimate changes. The soils translocated from low elevation to high elevation showed an increased respiration rate with decreased SOC content at the end of the experiment, which indicated that the increased soil moisture and altered soil microbes might affect respiration rates. The soils translocated from high elevation to low elevation also showed an increased respiration rate with reduced SOC at the end of the experiment, indicating that increased temperature at low elevation enhanced decomposition rates. Temperature and initial soil source quality impacted soil respiration significantly. With the predicted warming climate in the Caribbean, these tropical soils at high elevations are at risk of releasing sequestered carbon into the atmosphere.

  5. Tracing the source of soil organic matter eroded from temperate forest catchments using carbon and nitrogen isotopes

    Science.gov (United States)

    Emma P. McCorkle; Asmeret Asefaw Berhe; Carolyn T. Hunsaker; Dale W. Johnson; Karis J. McFarlane; Marilyn L. Fogel; Stephen C. Hart

    2016-01-01

    Soil erosion continuously redistributes soil and associated soil organic matter (SOM) on the Earth's surface, with important implications for biogeochemical cycling of essential elements and terrestrial carbon sequestration. Despite the importance of soil erosion, surprisingly few studies have evaluated the sources of eroded carbon (C). We used natural abundance...

  6. Variation in soil carbon dioxide efflux at two spatial scales in a topographically complex boreal forest

    Science.gov (United States)

    Kelsey, Katharine C.; Wickland, Kimberly P.; Striegl, Robert G.; Neff, Jason C.

    2012-01-01

    Carbon dynamics of high-latitude regions are an important and highly uncertain component of global carbon budgets, and efforts to constrain estimates of soil-atmosphere carbon exchange in these regions are contingent on accurate representations of spatial and temporal variability in carbon fluxes. This study explores spatial and temporal variability in soilatmosphere carbon dynamics at both fine and coarse spatial scales in a high-elevation, permafrost-dominated boreal black spruce forest. We evaluate the importance of landscape-level investigations of soil-atmosphere carbon dynamics by characterizing seasonal trends in soil-atmosphere carbon exchange, describing soil temperature-moisture-respiration relations, and quantifying temporal and spatial variability at two spatial scales: the plot scale (0–5 m) and the landscape scale (500–1000 m). Plot-scale spatial variability (average variation on a given measurement day) in soil CO2 efflux ranged from a coefficient of variation (CV) of 0.25 to 0.69, and plot-scale temporal variability (average variation of plots across measurement days) in efflux ranged from a CV of 0.19 to 0.36. Landscape-scale spatial and temporal variability in efflux was represented by a CV of 0.40 and 0.31, respectively, indicating that plot-scale spatial variability in soil respiration is as great as landscape-scale spatial variability at this site. While soil respiration was related to soil temperature at both the plot- and landscape scale, landscape-level descriptions of soil moisture were necessary to define soil respiration-moisture relations. Soil moisture variability was also integral to explaining temporal variability in soil respiration. Our results have important implications for research efforts in high-latitude regions where remote study sites make landscape-scale field campaigns challenging.

  7. Key biogeochemical factors affecting soil carbon storage in Posidonia meadows

    KAUST Repository

    Serrano, Oscar

    2016-08-15

    Biotic and abiotic factors influence the accumulation of organic carbon (C-org) in seagrass ecosystems. We surveyed Posidonia sinuosa meadows growing in different water depths to assess the variability in the sources, stocks and accumulation rates of Corg. We show that over the last 500 years, P. sinuosa meadows closer to the upper limit of distribution (at 2-4 m depth) accumulated 3- to 4-fold higher C-org stocks (averaging 6.3 kg C-org m(-2) at 3- to 4-fold higher rates (12.8 gC(org) m(-2) yr(-1) ) compared to meadows closer to the deep limits of distribution (at 6-8 m depth; 1.8 kg C-org m(-2) and 3.6 g C-org m(-2) yr(-1) . In shallower meadows, C-org stocks were mostly derived from seagrass detritus (88% in average) compared to meadows closer to the deep limit of distribution (45% on average). In addition, soil accumulation rates and fine-grained sediment content (< 0.125 mm) in shallower meadows (2.0 mm yr(-1) and 9 %, respectively) were approximately 2-fold higher than in deeper meadows (1.2 mm yr(-1) and 5 %, respectively). The C-org stocks and accumulation rates accumulated over the last 500 years in bare sediments (0.6 kg C-org m(-2) and 1.2 g C-org m(-2) yr(-1)were 3- to 11-fold lower than in P. sinuosa meadows, while fine-grained sediment content (1 %) and seagrass detritus contribution to the Corg pool (20 %) were 8- and 3-fold lower than in Posidonia meadows, respectively. The patterns found support the hypothesis that Corg storage in seagrass soils is influenced by interactions of biological (e.g., meadow productivity, cover and density), chemical (e.g., recalcitrance of Corg stocks) and physical (e.g., hydrodynamic energy and soil accumulation rates) factors within the meadow. We conclude that there is a need to improve global estimates of seagrass carbon storage accounting for biogeochemical factors driving variability within habitats.

  8. Laboratory-scale model of carbon dioxide deposition for soil stabilisation

    Directory of Open Access Journals (Sweden)

    Mohammad Hamed Fasihnikoutalab

    2016-04-01

    Full Text Available Olivine sand is a natural mineral, which, when added to soil, can improve the soil's mechanical properties while also sequester carbon dioxide (CO2 from the surroun