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Theses

Priming effect : vers un outil de gestion de la fertilité des sols cultivés à Madagascar

Abstract : The priming effect (PE) is the supplementary mineralization of soil organic matter (MOS) after the addition of fresh organic matter. This phenomenon would be generated by two distinct mechanisms, stoichiometric decomposition and "nutrient mining", having their own dynamics, their own actors, their own determinants and their own MO stock targeted. The first would be related to the sequestration of MO in the soil and the other to its destabilization. Understanding how to manage the balance between these processes through agricultural practices, would allow to improve the fertility of soil cultivated in a tropical environment in a context of climate change.To identify the determinants, actors and effects of climate and agricultural practices on the various processes generating PE, we have combined soil physicochemical characterization, characterization of microbial communities and monitoring of mineralization of MO by isotopic techniques. Thus, we were able to identify different bacterial and fungal populations, associated with processes, which we classified in the functional guilds. The size of these guilds determined the balance between the processes, and was correlated with the quality of the MO present in the soil. Specifically, we showed that stoichiometric PE was favored in soils enriched with high quality organic matter and nutrients, N and P, thus maintaining a strong community of decomposers. These decomposers also limit the access of miners to the provided new organic matter hence limiting PE by "nutrient extraction". On agricultural plots, our results suggest that non-tillage, legume-cereal rotations and compost amendments favor these decomposers responsible for the stoichiometric priming effect and thus potentially the long-term stabilization of organic matter in soils.
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https://tel.archives-ouvertes.fr/tel-01848792
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Submitted on : Wednesday, July 25, 2018 - 10:54:25 AM
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  • HAL Id : tel-01848792, version 1

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Kanto Razanamalala. Priming effect : vers un outil de gestion de la fertilité des sols cultivés à Madagascar. Sciences agricoles. Montpellier SupAgro, 2017. Français. ⟨NNT : 2017NSAM0047⟩. ⟨tel-01848792⟩

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