Crop-pasture rotation: a strategy to reduce soil greenhouse gas emissions in the Brazilian Cerrado.

摘要

The objective of this study was to quantify the soil greenhouse gas (GHG) balance after the conversion of native vegetation (NV) to pasture and agricultural land and the conversion of agriculture to crop-pasture rotation (CPR) by evaluating changes in C stocks and N₂O and CH₄ fluxes. Soil sampling was carried out in March 2007 and April 2009 and GHG fluxes were sampled nine times between April 2007 and March 2009. The conversion of NV to pasture and agriculture decreased soil C stocks, with loss rates ranging from 0.25 to 0.64 Mg C ha-1 yr-1, respectively. The implementation of CPR in agriculture areas increased soil C stocks by 0.60 Mg ha-1 yr-1. N₂O emissions were higher in CPR and lower in NV. Emission of 1.03 kg CH₄-C ha-1 yr-1 was observed in pasture, while in other areas consumption of CH₄ was observed. The net GHG emission from the soil, including all GHG expressed in C-equivalent, indicated that the conversion of NV to pasture and agricultural land results in emissions of 0.54 and 0.72 Mg C ha-1 yr-1, respectively. In contrast, the adoption of CPR in areas under crop succession was a sink of 0.36 Mg ha-1 yr-1. Among the evaluated land use changes, only the implementation of CPR proved to be a good strategy to mitigate soil GHG emissions in Brazilian Cerrado.