Emissions of CH_4 and N_2O from Paddy Soil in South China Under Different Fertilization Patterns

A field experiment was conducted to study the effects of different fertilization patterns on CH4 and N2O emissions from paddy soil.Methane emissions displayed a single peak curve during rice growing period. The emission peak occurred earlier for late rice than for early rice variety, and the peak value was higher in the former than in the latter. The emitted CH4 ranged from-0.29~14.83 mg·m-2·h-1,-6.09~31.54 mg·m-2·h-1,-0.11~22.87 mg·m-2·h-1for early and late rice in 2012 and early rice in 2013, respectively. The N2 O fluxes in paddy soil were quite low and varied little among different rice seasons. Compared with farmers ′ practice(FP), the treatment with stabilized nitrogen fertilizer combined with methane inhibitor(SN)showed the lowest seasonal total CH4 emission, and effectively reduced seasonal CH4 emission fluxes by 34.1%, 28.4% and 7.7% in early and late rice in 2012 and early rice in 2013, respectively. The partial global warming potential(p GWP)per unit output showed that SN treatment reduced the p GWP by 31.0% and 17.8% for CH4 and N2O, respectively, in comparison with FP. In conclusion, CH4 was the most important greenhouse gas in rice cropping system in South China Region, and SN could serve as an effective measure to reduce greenhouse gas emissions.