Poster (Painel)
78-1 | N2O Emission from Nitrogen Fertilization in Sugarcane | Authors: | VARGAS, V.P. (IAC - Instituto Agronômico) ; CANTARELLA, H. (IAC - Instituto Agronômico) ; MONTEZANO, Z.F. (IAC - Instituto Agronômico) ; SCILLA, F. (IAC - Instituto Agronômico) ; SOARES, J.R. (IAC - Instituto Agronômico) ; ANDRADE, C.A. (EMBRAPA - Empresa Brasileira de Pesquisa Agropecuária - Meio Ambiente) ; ROSSETO, R. (APTA - Agência Paulista de Tecnologia dos Agronegócios) ; GAVA, G.J.C. (APTA - Agência Paulista de Tecnologia dos Agronegócios) ; CARMO, J.B. (UFSCAR - SOROCABA - Universidade Federal de São Carlos - Campus Sorocaba) |
Resume Reduction of greenhouse gases emission is an important reason for the production of first generation ethanol from sugarcane. However the environmental efficiency of ethanol has been questioned on the ground of the emissions of nitrous oxide during crop production. This study aimed at evaluating N-N2O from the soil emissions during the cane plant cycle as a function of nitrogen fertilization and inoculation with diazotrophic bacteria (IN) in two sites: Jaú (sandy loam soil) and Piracicaba (clay soil). Gas fluxes were measured by static chambers in the treatments with the following N rates in kg ha-1: 0 (control); 0+IN; 60; 60+IN, and 90 kg. The N fertilizer was incorporated into the planting furrow. Emission of N-N2O started to be affected by N fertilization after the 16th day in Jaú and the 20th day in Piracicaba, although in the latter site N-N2O fluxes increased in all treatments after the 12th day due to rain and irrigation. In approximately 300 days of evaluation, N-N2O fluxes ranged from 37 to 3840 μµg N m-2 day-1 in Piracicaba and from 19 to 5141 μµg N m-2 day-1 in Jaú. In Jaú the peak emission for the period of assessment was 4076 μµg N m-2 day-1 on the average of the treatments that received N fertilization. Despite the decline in emissions after the initial phase, higher emissions in the application of 90 kg N ha-1 in Piracicaba were found up to 200 days. The emission of inoculated plots did not differ from that observed in control plots in both sites. N-N2O fluxes in the line were related with N-NO3- level and C-CO2 fluxes in both sites. The percentage of fertilizer N emitted as N-N2O until the 20th day was 0.13% and 0.36% for Piracicaba and Jaú, respectively. Keyword: nitrogen fertilizer emission factor, global warming, nitrous oxide fluxes, urea |