Nitrous oxide flux from soil with Urochloa brizantha under nitrogen fertilization in Honduras

Abstract

The emission of nitrous oxide is considerable in livestock systems, influenced by nitrogen fertilization and edaphoclimatic conditions. The aim of the research was to measure the flux of nitrous oxide (N2O) from the soil under Urochloa brizantha with nitrogen fertilization. In the pastures, a randomized complete block design was established with four replicates and three treatments, consisting of 2 m2 plots with U. brizantha fertilized with urea, bokashi and without fertilizer application. The gas samples were collected over three months between the rainy and dry seasons using the static closed chamber methodology. The samples related to the soil and plants were taken at a depth of 15 cm under undisturbed conditions every month, to quantify: gravimetric moisture, ammonium, nitrate, total carbon, total nitrogen, carbon/nitrogen ratio, and plant dry matter (DM). The ANAVA registered a significant difference between treatments for N2O, with the application of urea promoting higher accumulated flows (0.37 mg N2O m-2 h-1), followed by bokashi (0.34 mg N2O m-2 h-1) and lastly by the control (0.27 mg N2O m-2 h-1). The daily emission of the gas fluctuated in the rainy season, when soil moisture promoted higher emission peaks compared to the dry season. The fractions of nitrogen, carbon and DM were not affected by the treatments. The use of urea and the anaerobic conditions of soil due to the rains generated higher N2O values, while the organic amendment, bokashi, was the best alternative for the greenhouse gas mitigation and soil conservation.