Storage and forms of organic carbon in a no-tillage under cover crops system on clayey Oxisol in dryland rice production (Cerrados, Brazil)
2007
Metay, Aurélie | Alves Moreira, José Aloisio | Bernoux, Martial | Douzet, Jean-Marie | Feigl, Brigitte | Feller, Christian | Maraux, Florent | Oliver, Robert | Scopel, Eric | Fonctionnement et conduite des Systèmes de culture Tropicaux et Méditerranéens ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro) | Ecole Supérieure d’Agro-Développement International (ISTOM) | Empresa Brasileira de Pesquisa Agropecuária (Embrapa) ; Ministério da Agricultura, Pecuária e Abastecimento [Brasil] (MAPA) ; Governo do Brasil-Governo do Brasil | Institut de Recherche pour le Développement (IRD) | Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad) | Centro de Energia Nuclear na Agricultura ; Universidade de São Paulo = University of São Paulo (USP) | Food and Agriculture Organization of the United Nations [France] (FAO) ; Food and Agriculture Organization of the United Nations [Rome, Italie] (FAO)
Correspondance: [email protected]
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Mostrar más [+] Menos [-]Inglés. The management and enhancement of soil organic carbon (SOC) is very important for agriculture (fertility) as well as for the environment (carbon (C) sequestration). Consequently, changes in soil management may alter SOC content. No-tillage (NT) practices are potential ways to increase SOC. We studied the SOC from agricultural soils in the Cerrados in Central Brazil. We compared two different tillage systems: conservation agriculture with no-tillage under cover crops (NT) and disc tillage (DT) for 5 years in a context of rainfed rice production. The soil is a dark red Oxisol with high clay content (about 40%). The objectives of the study were: (i) to evaluate the short-term (5 years) impact of tillage systems on SOC stocks in an Oxisol and (ii) to better understand the dynamics of SOC in different fractions of this soil. We first studied the initial situation in 1998, and compared it to the 2003 situation. NT with cover crop (Crotalaria) was found to increase the storage of C in the topsoil layer (0-10 cm) compared to DT. The difference observed for the 0-10 cm layer under NT in comparison with DT represented C enrichment under no-tillage amounting to 0.35 Mg C ha(-1) year(-1) and corresponding to less than 10% of cover crops residues returned to the soil. A particle-size fractionation of soil organic matter (SOM) showed that differences in total SOC between NT and DT mainly affected the 0-2 mu m fraction and, to a smaller extent the 2-20 mu m fraction.This specific enrichment of SOC in the silt and clay fraction was attributed to (i) the storage of a water soluble C in the field and (ii) the effect of soil biota and especially fauna activity. The mean residence time of carbon associated with the fine fractions being rather long, it might be assumed that the preferential storage in fine fractions resulted in a long-term carbon storage. This study suggests a positive short-term effect of a no-tillage system on C sequestration in an Oxisol
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