Effects of irrigation method and rice straw incorporation on CH4 emissions of paddy fields in Northeast China

Irrigation methods and rice straw incorporation (RSI) are two major factors influencing CH4 emissions from paddy fields. However, their effects have never been studied in an RSI/alternate-year system in the cold region of Northeast China. The present study involved a 2-year field experiment analyzing the effects of irrigation method and RSI on CH4 emissions. Our results showed that controlled irrigation (CI) significantly decreased cumulative CH4 emissions by 55% when compared to flood irrigation (FI). RSI increased CH4 emissions in both CI and FI. CI accelerated the decreasing rate of straw residual while decreasing the total cumulative CH4 over the 2 years. The cumulative CH4 emissions of treatments with RSI were higher in the first year than in the second year. Our results suggest that CI with 6 t hm(-2) of RSI is an ideal strategy to mitigate CH4 emissions in an RSI/alternate-year system in Northeast China.