**3.4 Intermittent drainage**

Intermittent drainage involves repeated free drainage and irrigation. It has the advantage of improving soil oxidation conditions by enhancing root activity, increasing soil carrying capacity and ultimately reducing water input that leads to anaerobic conditions. It enhances the diffusion of oxygen into the soil, increases the aerobic area and reduces the production of CH4 [22] pointed out that compared with traditional floods, intermittent drainage can reduce CH4 emissions by 44%. Hardy [23] also showed that, compared with permanent floods, intermittent drainage can reduce CH4 emissions by 15%. N2O emission during intermittent irrigation strongly depends on the flooding conditions of the field. Different water regimes in rice fields lead to sensitive changes in N2O emissions [17]. Nevertheless [24, 25] reported that compared with traditional floods, the global warming potential (CH4 and N2O) of intermittent irrigation was reduced by 34% and 54%, respectively.
