Abstract
Alternate wetting and drying (AWD) irrigation is effective at reducing methane (CH 4 ) emissions in rice cultivation. To investigate the effect of the infiltration rate on AWD effectiveness in terms of CH 4 emissions, rice was cultivated in pots with three different infiltration rates under AWD. Under intermittent irrigation, the soil was more oxidative than is generally required for CH 4 production (redox potential [Eh] > −150 mV), regardless of the infiltration rate. CH 4 emission was suppressed by at least 37% compared to continuous flooding and no‐infiltration conditions; however, temporarily elevated emission caused by drainage below saturation was observed 1–2 h after the flooding receded. This result is important for accurately determining CH 4 emissions in water management techniques such as AWD. CH 4 emissions during the heading stage, including temporarily elevated emissions after flooding receded, were greatest under the highest infiltration rate (18 mm day −1 ). The infiltration rate did not affect the rate of soil Eh reduction; however, the total organic carbon concentration in the drainage water suggested that more carbon, a methanogen substrate, migrated to the bottom of the pot with increasing infiltration rate, which likely increased CH 4 emissions. This study will aid in the examination of ponding water management techniques to control CH 4 emissions in rice production.