Effects of Nitrogen Addition on Gas Fluxes and Nitrification in Cerrado Soil Under a Controlled Incubation Assay by Land Use

This study evaluated the effects of ammonium sulfate [(NH4)2SO4] addition and land-use history on greenhouse gas emissions (CH4, CO2, N2O) and inorganic nitrogen dynamics (NH4+ and NO3−) in Brazilian Cerrado soils. The objective was to determine how fertilization interacts with native and agricultural soils to regulate key biogeochemical processes. Soil samples from native and agricultural areas were collected in four regions (Araras, Sorocaba, Itirapina, and Brasília), representing contrasting pedoclimatic conditions and soil textures under different cropping systems. Samples were incubated under controlled conditions, with greenhouse gas fluxes analyzed by gas chromatography and inorganic nitrogen concentrations determined by colorimetric methods. Nitrogen fertilization inhibited CH4 consumption in native and agricultural soils and reversed fluxes to emissions in sandy soils. CO2 emissions increased in native soils but decreased in agricultural soils, suggesting effects of soil fertility and carbon stocks. N2O emissions increased mainly in native soils, reflecting intensified nitrification and denitrification, whereas agricultural soils responded heterogeneously. Nitrogen addition altered NH4+ and NO3− consumption, indicating enhanced oxidation and microbial assimilation. These results demonstrate that land-use history influences soil biogeochemical responses to nitrogen, underscoring the importance of site-specific fertilization in mitigating emissions and promoting sustainability in the Cerrado.