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Potential carbon storage in soil after exogenous organic matter applications

Abstract : The application of Exogenous Organic Matters (EOMs) of residual origin issued from agricultural, urban or industrial activities on croplands allows to increase soil organic matter (SOM) content and to improve soil fertility. Additionally, it could play a significant role in the mitigation of the net emissions of greenhouse gazes through C storage in soil. The development of predictive tools is necessary to better estimate the fate of EOMs in soil in the long-term. Additionally it is important to better know under which form the organic matter (OM) is accumulated into SOM after EOM application, this conditioning the potential reversibility of C sequestration in soil.
This study aims at better understanding and predicting the dynamics of incorporation of the organic matter from exogenous organic matters (EOMs: manures, slurries, composts, sewage sludges etc.) into soil organic matter (SOM). It has been carried out in three steps: (i) the development of tools for EOM characterization in the laboratory to specify the chemical nature of EOMs and better estimate their fate in soil, (ii) the parameterization of the RothC model to simulate the C accumulation in soil following repeated EOM applications and (iii) the study of the changes in the chemical composition of SOM after repeated applications of EOMs.
The study of the chemical composition of the soluble fraction of the Van Soest fractionation method revealed that the chemical nature of this fraction changed during EOM treatment by composting: this fraction is rich in polysaccharides at the beginning of composting and enriched in N-containing compounds stabilized at the end of composting.
The potential of near infrared spectroscopy (NIRS) for the characterization of EOMs and their fate in soil was then assessed. Satisfactory predictions were obtained for the C and N contents of EOMs and for the Van Soest biochemical fractions of EOMs. The indicator of remaining organic C in soil (IROC), estimator of the residual fraction of EOM organic matter in soil over the long-term has been predicted satisfactorily. The potential of C storage over the long-term in soils subjected to repeated applications of EOMs was studied using results of 4 medium and long-term field experiments. Repeated applications of EOMs resulted in significant increases in soil C stocks that could be well reproduced with the RothC model that has been parameterized for simulation of C accumulation in soil following various EOM applications.
Changes in SOM chemical composition due to the application of EOMs were studied in one of the field experiments (Qualiagro experiment). The SOM fraction of size > 50 µm was preferentially modified by EOMs inputs and enriched in lignin. The composition of the 0-50 µm SOM fraction was also modified but to a lesser extent and the changes were less directly related to the composition of the applied EOMs.
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Submitted on : Thursday, June 23, 2011 - 2:40:37 PM
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  • HAL Id : pastel-00602825, version 1
  • PRODINRA : 330567

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Clément Peltre. Potential carbon storage in soil after exogenous organic matter applications. Soil study. AgroParisTech, 2010. English. ⟨NNT : 2010AGPT0076⟩. ⟨pastel-00602825⟩

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