Storage and forms of organic carbon in a no-tillage under cover crops system on clayey Oxisol in dryland rice production (Cerrados, Brazil)

Abstract 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 μm fraction and, to a smaller extent the 2–20 μm 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.

[1]  P. Dagnelie,et al.  The 'orie et me 'thodes statistiques: applications agronomiques , 1970 .

[2]  A. Albrecht,et al.  Soil organic carbon sequestration in tropical areas. General considerations and analysis of some edaphic determinants for Lesser Antilles soils , 2001, Nutrient Cycling in Agroecosystems.

[3]  P. Lavelle,et al.  Effects of earthworms on soil organic matter and nutrient dynamics following earthworm inoculation in field experimental situations , 1999 .

[4]  O. M. Castro,et al.  Long-term tillage and crop rotation effects on soil chemical properties of a Rhodic Ferralsol in southern Brazil , 1999 .

[5]  S. Urquiaga,et al.  Change in carbon and nitrogen stocks in soil under 13 years of conventional or zero tillage in southern Brazil , 2003 .

[6]  C. Feller,et al.  Effet de la texture sur le stockage et la dynamique des matières organiques dans quelques sols ferrugineux et ferrallitiques (Afrique de l'Ouest, en particulier) , 1991 .

[7]  C. Feller,et al.  Physical control of soil organic matter dynamics in the tropics , 1997 .

[8]  A. Martin,et al.  Short- and long-term effects of the endogeic earthworm Millsonia anomala (Omodeo) (Megascolecidæ, Oligochæta) of tropical savannas, on soil organic matter , 1991, Biology and Fertility of Soils.

[9]  I. Bertol,et al.  Características químicas de um cambissolo húmico afetadas por sistemas de preparo, com ênfase à matéria orgânica , 1999 .

[10]  Ariel E. Lugo,et al.  Tropical forests as sinks of atmospheric carbon , 1992 .

[11]  P. Lavelle,et al.  Earthworm Management in Tropical Agroecosystems , 1999 .

[12]  C. Feller,et al.  Effet du paillis des résidus de canne à sucre sur la séquestration de carbone dans un sol ferrallitique argileux du Brésil , 2003 .

[13]  Rattan Lal,et al.  Organic matter dynamics and carbon sequestration rates for a tillage chronosequence in a Brazilian Oxisol , 2001 .

[14]  F. Nachtergaele,et al.  World Reference Base for Soil Resources. Introduction , 1998 .

[15]  B. Christensen Physical fractionation of soil and structural and functional complexity in organic matter turnover , 2001 .

[16]  Martial Bernoux,et al.  Carbon cycling and sequestration opportunities in South America: the case of Brazil , 2004 .

[17]  C. Feller,et al.  A routine method to study soil organic matter by particle‐size fractionation: Examples for tropical soils , 1995 .

[18]  P. Machado,et al.  Soil organic carbon and fractions of a Rhodic Ferralsol under the influence of tillage and crop rotation systems in southern Brazil , 2002 .

[19]  Anne-Sophie Perrin,et al.  Cropping systems, carbon sequestration and erosion in Brazil, a review , 2006 .

[20]  R. Lal Soils and Global Change , 1995 .

[21]  R. Lal Soil Quality and Agricultural Sustainability , 1998 .

[22]  H. Riezebos,et al.  Influence of land use change and tillage practice on soil organic matter in southern Brazil and eastern Paraguay , 1998 .

[23]  C. Feller La matiere organique dans les sols tropicaux a argile 1:1 : recherche de compartiments organiques fonctionnels. une approche granulometrique , 1994 .

[24]  C. C. Filho,et al.  Estabilidade dos agregados e sua relação com o teor de carbono orgânico num latossolo roxo distrófico, em função de sistemas de plantio, rotações de culturas e métodos de preparo das amostras , 1998 .

[25]  Flávio Luiz Foletto Eltz,et al.  Potencial de culturas de cobertura em acumular carbono e nitrogênio no solo no plantio direto e a melhoria da qualidade ambiental , 2001 .

[26]  D. Resck,et al.  Comportamento de diferentes sistemas de manejo como fonte ou depósito de carbono em relação à vegetação de Cerrado , 1999 .

[27]  C. Bayer,et al.  Organic matter storage in a sandy clay loam Acrisol affected by tillage and cropping systems in southern Brazil. , 2000 .

[28]  C. Silva,et al.  Soil management under no-tillage systems in the tropics with special reference to Brazil , 2001, Nutrient Cycling in Agroecosystems.

[29]  P. Lavelle,et al.  Phosphorus transformations in a ferralsol through ingestion by Pantoscolex corethrurus, a geophagous earthworm , 1998 .

[30]  C. Bayer,et al.  Stocks and humification degree of organic matter fractions as affected by no-tillage on a subtropical soil , 2004, Plant and Soil.

[31]  J. Mielniczuk,et al.  Características químicas de um podzólico vermelho-escuro afetadas por sistemas de culturas , 1992 .

[32]  C. Bayer,et al.  Effect of no-till cropping systems on soil organic matter in a sandy clay loam Acrisol from Southern Brazil monitored by electron spin resonance and nuclear magnetic resonance , 2000 .

[33]  B. Christensen Physical Fractionation of Soil and Organic Matter in Primary Particle Size and Density Separates , 1992 .

[34]  J. Tisdall,et al.  Organic matter and water‐stable aggregates in soils , 1982 .

[35]  K. Paustian,et al.  Sources and composition of soil organic matter fractions between and within soil aggregates , 2001 .

[36]  G. Dersch,et al.  Effects of agronomic practices on the soil carbon storage potential in arable farming in Austria , 2001, Nutrient Cycling in Agroecosystems.

[37]  R. Lal Soil carbon sequestration to mitigate climate change , 2004 .

[38]  R. Roscoe,et al.  Tillage effects on soil organic matter in density fractions of a Cerrado Oxisol , 2003 .