LONG-TERM MANURING AND FERTILIZER EFFECTS ON DEPLETION OF SOIL ORGANIC CARBON STOCKS UNDER PEARL MILLET-CLUSTER BEAN-CASTOR ROTATION IN WESTERN INDIA

Fire and grazing are commonplace in Australian tropical savannas and the effects of these management practices on soil organic carbon stocks (SOC) is not well understood. A long-term (20 years) experiment studying the effects of fire on a grazed semi-arid tropical savanna was used to increase this understanding. Treatments, including frequency of fire (every 2, 4 and 6 years), season of fire [early (June) vs late (October) dry season] and unburnt control plots, were imposed on Vertosol grassland and Calcarosol woodland sites, which were grazed. Additionally long-term enclosures [unburnt (except the Calcarosol in 2001) and ungrazed since 1973] on each soil type adjacent to each site were sampled, although not included in statistical analyses. SOC stocks were measured to a soil depth of 0.3 m using a wet oxidation method (to avoid interference by carbonates) and compared on an equivalent soil mass basis. Significant treatment differences in SOC stocks were tested for, while accounting for spatial background variation within each site. SOC stocks (0–0.3 m soil depth) ranged between 10.1 and 28.9 t ha–1 (Vertosol site) and 20.7 and 54.9 t ha–1 (Calcarosol site). There were no consistent effects of frequency or season of fire on SOC stocks, possibly reflecting the limited statistical power of the study and inherent spatial variability observed. Differences in the response to frequency and season of fire observed between these soils may have been due to differences in clay type, plant species composition and/or preferential grazing activity associated with fire management. There may also have been differences in C input between treatments and sites due to differences in the herbage mass and post-fire grazing activity on both sites and changed pasture composition, higher herbage fuel load, and a reduction in woody cover on the Vertosol site. This study demonstrated the importance of accounting for background spatial variability and treatment replication (in the absence of baseline values) when assessing SOC stocks in relation to management practices. Given the absence of baseline SOC values and the potentially long period required to obtain changes in SOC in rangelands, modelling of turnover of SOC in relation to background spatial variability would enable management scenarios to be considered in relation to landscape variation that may be unrelated to management. These considerations are important for reducing uncertainty in C-flux accounting and to provide accurate and cost-effective methods for land managers considering participation in the C economy.

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Critical carbon inputs to maintain soil organic carbon stocks under long-term finger-millet (Eleusine coracana [L.] Gaertn.) cropping on Alfisols in semiarid tropical India

Journal of Plant Nutrition and Soil Science ◽

10.1002/jpln.201000429 ◽

2012 ◽

Vol 175 (5) ◽

pp. 681-688 ◽

Cited By ~ 15

Author(s):

Cherukumalli Srinivasarao ◽

Bandi Venkateswarlu ◽

Anil Kumar Singh ◽

Kanuparthy Pandu Ranga Vittal ◽

Sumanta Kundu ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Finger Millet ◽

Carbon Stocks ◽

Eleusine Coracana ◽

Soil Organic Carbon Stocks

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What is the impact of human wastewater biosolids (sewage sludge) application on long-term soil carbon sequestration rates? A systematic review protocol

Environmental Evidence ◽

10.1186/s13750-021-00221-3 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Mike J. Badzmierowski ◽

Gregory K. Evanylo ◽

W. Lee Daniels ◽

Kathryn C. Haering

Keyword(s):

Carbon Sequestration ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Carbon ◽

Full Text ◽

Land Application ◽

Carbon Stocks ◽

Soil Organic Carbon Stocks ◽

The Impact

Abstract Background Human wastewater biosolids, hereafter referred to as biosolids, are produced in significant quantities around the world and often applied to an extensive land mass including agricultural fields, forests, mine lands, and urban areas. Land-application of biosolids has been reported in peer-reviewed and non-peer-reviewed work to change soil organic carbon stocks in varying amounts. Determining the potential of soil organic carbon (SOC) stock change and sequestration from biosolids land application is critical for biosolids producers and users to gain access to carbon credit markets. Our review question is, "what is the impact of biosolids application on long-term soil carbon sequestration rates?” We look to explore this main question with the follow-up, "does biosolids processing methods and characteristics, application method, soil properties, land management and other modifiers affect rates of carbon accumulation from land-applied biosolids?" Methods Searches will be conducted using online databases (i.e., Web of Science Core Collection, CAB Abstracts, Scopus, ProQuest Dissertations & Theses Global), search engines (Google Scholar and Microsoft Academic), and specialist websites to find primary field studies and grey literature of biosolids land-application effects on soil organic carbon stocks. We will use English search terms and predefined inclusion criteria of: (1) a field study of at least 24 months that reports soil organic carbon/matter (SOC/SOM) concentrations/stocks; (2) has two types of treatments: (i) a control (non-intervention AND/OR synthetic fertilizer) AND (ii) a biosolids-based amendment; and (3) information of amendment properties and application dates and rates to estimate the relative contribution of the applied materials to SOC changes. We will screen results in two stages: (1) title and abstract and (2) full text. A 10% subset will be screened by two reviewers for inclusion at the title and abstract level and use a kappa analysis to ensure agreement of at least 0.61. All results in the full text stage will be dual screened. Data will be extracted by one person and reviewed by a second person. Critical appraisal will be used to assess studies’ potential bias and done by two reviewers. A meta-analysis using random effects models will be conducted if sufficient data of high enough quality are extracted.

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Increasing soil organic carbon stocks in croplands: a multi-modelling analysis evaluating the carbon inputs required to maintain and increase soil organic carbon stocks in Europe

10.5194/ismc2021-18 ◽

2021 ◽

Author(s):

Elisa Bruni

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Stocks ◽

Future Climate Change ◽

Experimental Conditions ◽

Significant Interaction Effect ◽

Soil Organic Carbon Stocks ◽

The Impact ◽

Soc Stocks

<p>Soils represent the largest terrestrial reservoir of organic carbon on land and have the ability to sequester carbon dioxide from the atmosphere. Increasing soil organic carbon (SOC) stocks also improves soil fertility, water holding capacity and prevents erosion. Maintaining SOC stocks is particularly relevant in agricultural soils, where they have been depleted through historical land use. Simulation models representing the dynamics of carbon in the soil are used for predicting the impact of future climate change on SOC dynamics. It is necessary to reduce the uncertainties related to SOC predictions and increase confidence on long-term model simulations. Multi-modeling simulations allow predicting the evolution of SOC stocks, while estimating the uncertainty related to different modeling approaches.</p> <p>In this study, we used a multi-modeling ensemble (ICBM, AMG, RothC and Century) to estimate the amount of carbon inputs required to maintain and increase SOC stocks in 17 agricultural experiments around Europe. Models were run once without calibration and once fitting SOC stocks to long-term observations though parameters&#8217; optimization. Outputs were significantly different among the models and, although no effect of the optimization was found, we observed a significant interaction effect between models and parameters&#8217; optimization. We found that maintaining and increasing SOC stocks is realistic for some experimental conditions, but might be hard to implement at a larger scale.</p>

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Additional carbon inputs to reach a 4 per 1000 objective in Europe: feasibility and projected impacts of climate change based on Century simulations of long-term arable experiments

10.5194/bg-2020-489 ◽

2021 ◽

Author(s):

Elisa Bruni ◽

Bertrand Guenet ◽

Yuanyuan Huang ◽

Hugues Clivot ◽

Iñigo Virto ◽

...

Keyword(s):

Climate Change ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Temperature Increase ◽

Agricultural Practices ◽

Carbon Stocks ◽

Soil Organic Carbon Stocks ◽

Annual Carbon ◽

Soc Stocks

Abstract. The 4 per 1000 initiative aims to promote better agricultural practices to maintain and increase soil organic carbon stocks for soil fertility, food security and climate change adaptation and mitigation. The most straightforward way to enhance soil organic carbon stocks is to increase carbon inputs to the soil. In this study, we assessed the amount of organic carbon inputs that are necessary to reach a target of soil organic carbon stocks increase by 4 ‰ per year on average, for 30 years. We used the Century model to simulate soil organic carbon stocks in 14 European long-term agricultural experiments and assessed the required level of carbon inputs increase to reach the 4 per 1000 target. Initial simulated stocks were computed analytically assuming steady state. We compared modelled carbon inputs to different treatments of additional carbon used on the experimental sites (exogenous organic matter addition and one treatment with different crop rotations). We then analyzed how this would change under future scenarios of temperature increase. The model was calibrated to fit the control plot, i.e. conventional management without additional carbon inputs, and was able to reproduce the SOC stocks dynamics. We found that, on average among the selected experimental sites, annual carbon inputs will have to increase by 43.15 ± 5.05 %, which is 0.66 ± 0.23 MgC ha−1 per year (mean ± standard error), with respect to the control situation. The simulated amount of carbon inputs required to reach the 4 ‰ SOC increase was lower or similar to the amount of carbon inputs actually used in the majority of the additional carbon input treatments of the long-term experiments. However, Century might be overestimating the effect of additional C inputs on the variation of SOC stocks in some sites, since we found that treatments with additional carbon inputs were increasing by 0.25 % on average among the experimental sites. We showed that the modeled carbon inputs required to reach the target depended linearly on the initial SOC stocks. We estimated that annual carbon inputs would have to increase further due to temperature increase effect on decomposition rates, that is 54 % for a 1 °C warming and 120 % for a 5 °C warming.

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