Nitrous oxide emission from different sources of nitrogen fertilizer in Marandu grass pastures

Abstract

The world demand for beef has been increasing. Brazil has the largest commercial cattle herd when compared to the rest of the countries. However, the production of cattle in the country depends on techniques that are often flawed from an environmental point of view. Inadequate management and pasture degradation levels in livestock systems lead to reduced productivity and higher greenhouse gas (GHG) emissions. Among the GHGs, nitrous oxide (N2O) stands out, which is a gas with a high global warming potential (GWP). Nitrogen fertilization with different fertilizer sources can alter soil N2O emission fluxes. The present study aims to verify and quantify N2O emissions in Urochloa brizantha cv. Marandu (Marandu grass) submitted to different sources of nitrogen fertilizers, as well as to relate the emissions with the variables: (I) Ammonium-NH4+, (II) Nitrate-NO3-, (III) temperature, and (III) soil moisture. The study is under development at the FCAV/UNESP Forage Sector in Marandu grass pastures. The treatments used to consist of three types of nitrogen fertilizers: urea fertilization, ammonium sulfate fertilization, ammonium nitrate fertilization, and another treatment without the use of nitrogen fertilizer (control). Nitrous oxide emissions will be evaluated using five replicates (chambers) per treatment and quantification will be performed using the gas chromatography technique. The hypothesis of the present study is that N2O emissions from urea fertilization will be higher when compared to those from ammonium sulfate and ammonium nitrate fertilizers. (AU)