Water management — A tool for methane mitigation from irrigated paddy fields

Water drainage is considered to be one of the important practices that reduce the CH4 efflux from paddy fields. In this study, four different drainage systems (continuous flooding, tillering stage drainage, mid-season drainage and multiple drainage) were compared to find out the best one, for attenuation of CH4 emission from rice fields. Except for continuous flooding, from all the other three drainage systems, irrigation water from the paddy fields was drained out at the different stages of the crop cycle. Highest efflux of the methane was recorded from continuously flooded plots (346.6 mg/m2/day), followed by 9% less CH4 efflux from tillering stage drainage (315.1 mg/m2/day), 36.7% less efflux from mid-season drainage (219.3 mg/m2/day) and the least 41% CH4 efflux from multiple drainage plots (204.7 mg/m2/day). Among all the four different drainage systems applied, mid-season drainage and multiple drainage were found to be highly effective in mitigating methane efflux. Redox potential of the soil of the drainage system was found to be inversely proportional to the methane efflux from all the treatments.