Response of nitric and nitrous oxide fluxes to N fertilizer application in greenhouse vegetable cropping systems in southeast China

Abstract

It is of great concern worldwide that active nitrogenous gases in the global nitrogen cycle contribute to regional and global-scale environmental issues. Nitrous oxide (N 2 O) and nitric oxide (NO) are generally interrelated in soil nitrogen biogeochemical cycles, while few studies have simultaneously examined these two gases emission from typical croplands. Field experiments were conducted to measure N 2 O and NO fluxes in response to chemical N fertilizer application in annual greenhouse vegetable cropping systems in southeast China. Annual N 2 O and NO fluxes averaged 52.05 and 14.87 I 1/4g N m â '2 h â '1 for the controls without N fertilizer inputs, respectively. Both N 2 O and NO emissions linearly increased with N fertilizer application. The emission factors of N fertilizer for N 2 O and NO were estimated to be 1.43% and 1.15%, with an annual background emission of 5.07 kg N 2 O-N ha â '1 and 1.58 kg NO-N ha â '1, respectively. The NO-N/N 2 O-N ratio was significantly affected by cropping type and fertilizer application, and NO would exceed N 2 O emissions when soil moisture is below 54% WFPS. Overall, local conventional input rate of chemical N fertilizer could be partially reduced to attain high yield of vegetable and low N 2 O and NO emissions in greenhouse vegetable cropping systems in China.