CH4 and N2O emissions response to controlled irrigation of paddy fields

In order to study the effects of controlled irrigation on variations of CH4 and N2O emissions from paddy fields, CH4 and N2O emissions from paddy fields under controlled irrigation were investigated by the method of static chamber/gas chromatography. The results showed that CH4 emissions from controlled irrigation paddy fields were lower than those from traditional irrigation paddy fields during most of the rice growing season. The high CH4 emissions from controlled irrigation paddy fields were mainly observed during the former tillering period of rice, and the peaks were observed 1-2 days after soil dehydration. Compared with the traditional irrigation paddy fields, cumulative emission of CH4 from controlled irrigation paddy fields reduced by 81.2%-82.8%. The N2O emissions from controlled irrigation paddy fields were mostly higher than those from traditional irrigation paddy fields, and the peaks were observed 3-4 days after soil dehydration. Compared with the traditional irrigation paddy fields, cumulative emission of N2O from controlled irrigation fields increased by 121.8%-144.3%. However, the integrative global warming potential of CH4 and N2O on a 100-year horizon was significantly decreased by 15.0%-34.8% in the controlled irrigation paddy fields (p<0.05). These results suggest that controlled irrigation can significantly mitigate the integrative greenhouse effect caused by CH4 and N2O from paddy fields.