Abstract
AbstractAlternate wetting and drying (AWD) irrigation is effective at reducing methane (CH4) emissions in rice cultivation. To investigate the effect of the infiltration rate on AWD effectiveness in terms of CH4 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 CH4 production (redox potential [Eh] > −150 mV), regardless of the infiltration rate. CH4 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 CH4 emissions in water management techniques such as AWD. CH4 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 CH4 emissions. This study will aid in the examination of ponding water management techniques to control CH4 emissions in rice production.
Published Version
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