Mitigating net global warming potential and greenhouse gas intensity by intermittent irrigation under straw incorporation in Chinese double-rice cropping systems

To clarify the effect of water management on global warming potential and crop yield with rice straw returning in typical double-rice cropping systems, a field experiment was conducted in 2013–2016. The three strategies of water management included continuous flooding (F), flooding during the rice season but with drainage during the midseason and harvest time (F–D–F), and flooding during transplanting and tillering stages, drainage during the midseason and intermittent irrigation after midseason drainage (F–D–F–M). Compared with F plots, annual topsoil organic carbon sequestration rates were reduced by 10–45% and 49–66% for F–D–F and F–D–F–M plots, respectively. However, the annual CH4 emissions were significantly decreased by 33–52% and 46–69% for the F–D–F and F–D–F–M plots. As a result, the net annual global warming potential was reduced by 34–57% for F–D–F plots and 38–63% for F–D–F–M plots, respectively. Similarly, the greenhouse gas intensity was reduced 38–60% and 39–64% for F–D–F and F–D–F–M plots, respectively. These results suggested that intermittent irrigation has the potential to mitigate GHG emissions without sacrificing grain yield under rice straw returning in Chinese rice cropping systems.