Soil N2O emissions and N2O/(N2O+N 2) ratio as affected by different fertilization practices and soil moisture

The objective of this work was to evaluate the effect of the chemical nature and application frequency of N fertilizers at different moisture contents on soil N2O emissions and N2O/(N2O+N 2) ratio. The research was based on five fertilization treatments: unfertilized control, a single application of 80 kg ha-1 N-urea, five split applications of 16 kg ha-1 N-urea, a single application of 80 kg ha-1 N-KNO3, five split applications of 16 kg ha -1 N-KNO3. Cumulative N2O emissions for 22 days were unaffected by fertilization treatments at 32% water-filled pore space (WFPS). At 100% and 120% WFPS, cumulative N2O emissions were highest from soil fertilized with KNO3. The split application of N fertilizers decreased N2O emissions compared to a single initial application only when KNO3 was applied to a saturated soil, at 100% WFPS. Emissions of N2O were very low after the application of urea, similar to those found at unfertilized soil. Average N2O/(N 2O+N2) ratio values were significantly affected by moisture levels (p=0.015), being the lowest at 120% WFPS. The N 2O/(N2O+N2) ratio averaged 0.2 in unfertilized soil and 0.5 in fertilized soil, although these differences were not statistically significant.Fil: Ciarlo, Esteban Ariel. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente. Cátedra de Edafología; ArgentinaFil: Conti, Marta Elvira. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente. Cátedra de Edafología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; ArgentinaFil: Bartoloni, N.. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; ArgentinaFil: Rubio, Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Ingeniería Agrícola y Uso de la Tierra. Cátedra de Fertilidad y Fertilizantes; Argentin