Soil organic matter and greenhouse gas emissions in crop production systems under no-till

Abstract

Agricultural practices contribute with greenhouse gases emissions, so there is interest in identify cropping systems able to increase soil organic carbon (SOC) accumulation, and to promote the maintenance of stable MO. The objective of this work is to study C sequestration and C and N stocks in the soils under no-till (NT) as related with organic matter accumulation and quality. The study will be carried out in two areas under NT for at least eight years with different crop rotations, in Botucatu, state of São Paulo, Brazil. In the soil, it will be analyzed the organic matter quality by physical and chemical fractionation, and the total and inorganic N levels, and C and N microbial biomass levels. The following soill physical characteristics will be analysed: bulk density, particle density, porosity and aggregate stability. The straw on the soil will be evaluated periodically to determine dry matter, nutrients levels, C/N relation, and the levels of lignin, cellulose, hemicellulose and soluble carbohydrates. The fluxes of CO2, N2O and CH4 from soil will be determined twice a year, during the dry and the wet season. The aim is to identify, among different crop rotations, which has a positive balance in C accumulation in the soil and also to recommend species and management pracitces that would help to mitigate the greenhouse effect. (AU)