GREENHOUSE GAS EMISSIONS FROM SOIL IN DIFFERENT LAND USES AND MANAGEMENT IN THE BRAZILIAN SAVANNA

Resumo

Agricultural soils are an important greenhouse gas (GHG) source. In this study, we assess the GHG fluxes from soil under different land use and management in the most important grains producing region in Cerrado biome. So, our objective was quantifying the GHG fluxes (CO₂, CH₄ and N₂O) to verify the existence of relationships between these gases and obtain estimation of GHG fluxes through statistically correlation in Brazilian Savanna. GHG flux was measured in areas under i) native vegetation (NV), a grassy pasture (GP), a conventional-tillage (CT), and three areas under no-tillage (NT) with different crop succession. The results showed highest CO₂ emission in GP (135 mg m^-2 h^-1), while in CT verified lower emission (69 mg m^-2 h^-1). CH₄ fluxes showed different between land uses, in GP was found emission (32 µg m^-2 h^-1), while in other areas (NV, CT and NT) were observed influxes between -46 and -15 µg m^-2 h^-1. N₂O emission was highest in NV (16 µg m^-2 h^-1), while lowest in the NT (11 µg m^-2 h^-1). The CO₂ vs N₂O emissions showed significant correlation (r > 0.60, p < 0.01) except in GP, as the CO₂ vs CH₄ in NV, CT and NT (r > 0.55, p < 0.05) and, CH₄ vs N₂O in NV and NT (r > 0.50, p < 0.05). These results cannot permit to identify the processes involved in the GHG correlations, but, these statistical estimative and simple equations can provide rough estimates GHG flux through a simple field measurement.