Methane and nitrous oxide emissions from rice paddy fields as affected by nitrogen fertilisers and water management.

摘要

A field study was conducted in Jiangsu, China, during 1994 to assess the effects of N fertilizer application and intermittent irrigation on methane and N2O emissions. Ammonium sulphate and urea were applied at 0, 100 or 300 kg N/ha. Results indicated that methane emission decreased by 42 and 60% in the ammonium sulphate treatments and 7 and 14% in the urea treatments at rates of 100 and 300 kg N/ha, respectively, compared to the control. N2O emission increased significantly with an increase in N application rate. N2O emission was highest from ammonium sulphate treatments at the same application rate. A trade-off effect between CH4 and N2O emission was clearly observed. The N2O flux was very small when the rice paddy plots were flooded, but peakedat the beginning of the disappearance of floodwater. In contrast, the CH4 flux peaked during flooding and was significantly depressed by mid-season aeration. It is suggested that the integrative effects of water management and fertilizer application arevital in the mitigation of greenhouse gas emissions.