Soil nitrous oxide fluxes following cover crops management under tillage and no tillage in South Brazil

摘要

Emissions of N_2O were measured following cover crops management (oat - O and vetch - V) under tillage (CT) and no tillage (NT) in a silt loam Acrisol in South Brazil. Effects of tillage systems and residue management on N_2O emissions were examined over 55 days in 2007 and 54 days in 2008. Larger emissions were measured in 2008 compared to 2007. N_2O emissions increased in the presence of crops residues and were further increased in NT V7M in 2007 (193±84 ug N/m~2/ha) and in CT V/M in 2008 (431±138 ug N/m2/ha) and they are related to high water content and available soil nitrogen. Smallest fluxes of N_2O were measured from the NT O/M treatments, which 288±61 ug N/m2/ha in 2007 and 274±19 ug N/m~2/ha in 2008.