Nitrification inhibitor as strategy to mitigate N2O emissions in sugarcane production

Abstract

Nitrous oxide (N2O) emissions from nitrogen fertilization has a great environmental impact on the production of ethanol from sugarcane. A strategy to reduce N2O emissions from N fertilizers is through the addition of nitrification inhibitors. However, little is known about the efficiency of the inhibitors to mitigate the emissions and to increase sugarcane yield, especially when is associated with the addition of organic residues, such as sugarcane straw and vinasse. The aim of this project is to evaluate the efficiency of the nitrification inhibitor in nitrogen fertilization associated with the addition of organic residues in N2O emissions and in sugarcane yields. Additionally, the project aims to identify the main process associated with N2O production. To achieve these aims will be carried out studies under field and laboratory conditions. The first study is composed by two field experiments that aims to isolate the effects of N fertilization with the addition of nitrification inhibitor (DMPP) and different amounts of straw. The experiment will set up at different times, early and late harvest period. These experiments will be installed in ratoon areas in early and late harvest period. The experimental design is a factorial 3 x 4, which N fertilizers treatments (control - 0 N; 120 kg N ha-1 e 120 kg N ha-1 + DMPP) and 4 rates of straw (0, 5, 10 e 15 Mg ha-1). The second experiment will be carried out under controlled laboratory conditions to test the effect of vinasse addition on the efficiency of nitrification inhibitor in reducing N2O emissions. And finally, the third study will be composed by two field experiments and one laboratory experiment, in which Urea (U), Ammonium Nitrate (AN), DMPP and concentrated vinasse will be tested. In the field experiments, the N2O fluxes will be evaluated with the use of static chambers, and soil analyzes will be carried out to evaluate soil pH, N content in the form of ammonium (NH4 +), nitrite (NO2-) and nitrate (NO3 -). The ammonia (N-NH3-) volatilization will be quantified. In both field experiments, the crop yield will be evaluated using an instrumented truck. In incubation study, isotopic techniques (15N) will be used to characterize the different processes of N2O formation. It is expected with this project the characterization of the N2O emission due to different situations of N fertilizers application and organic residues management in sugarcane cultivation and indicate ways to mitigate the GHG emissions. (AU)