Soil greenhouse gas fluxes from vinasse application in Brazilian sugarcane areas

Sugarcane ethanol is the main liquid biofuel used in Brazil as a substitute for fossil fuels for the mitigation of greenhouse gas (GHG) emissions. However, ethanol production also produces GHG emissions during the agricultural phase through the disposal of its residues. Vinasse, as the main residue from ethanol production, may contribute to GHG emission during its storage, transportation and application to soil as ferti-irrigation. The objective of this study was to quantify the fluxes of CO2, CH4 and N2O resulting from vinasse application in sugarcane fields under different straw managements and to determine the N2O emission factor derived from this practice. This study was performed at the Boa Vista Farm, in São Paulo State, Brazil. The application of 200 m3 ha− 1 of vinasse tripled the CO2 emissions in areas with burnt or unburnt harvest systems. The consumption of CH4 was observed, supporting the hypothesis that this usually applied amount of vinasse to the soil does not necessarily result in CH4 emissions. The 46 kg of N contained in this dose of vinasse increased the release of N2O by the soil and resulted in emission factors of 0.68% and 0.44% for the burnt and unburnt areas, respectively. The fluxes of N2O and CH4, converted into CO2 eq, indicate that each m3 ha− 1 of vinasse applied to the soil emits 0.491 and 0.314 kg of CO2 eq. in the burnt and unburnt sugarcane areas, respectively.

► We quantified the GHG fluxes from vinasse application in sugarcane areas in Brazil.
► The vinasse application increased the CO2 and N2O emissions.
► Consumption of CH4 was observed.
► The N2O emission factors obtained were lower than proposed by IPCC.
► Our results contribute to evaluation of GHG emissions in ethanol production.