Indexed on: 20 Dec '18Published on: 20 Dec '18Published in: Environmental Science & Technology
Rice cultivation contributes 11% of the global 308 Tg CH anthropogenic emissions. The Alternate Wetting and Drying (AWD) irrigation practice can conserve water while reducing CH emissions through the deliberate, periodic introduction of aerobic soil conditions. This paper is the first to measure the impact of AWD on rice field CH emissions using the eddy covariance (EC) method. This method provides continuous, direct observations over a larger footprint than in previous, chamber-based approaches. Seasonal CH emissions from a pair of adjacent, production-sized rice fields under delayed flood (DF) and AWD irrigation were compared from 2015 to 2017. Across the two fields and three years, cumulative CH emissions in the production season were in the range from 7.1-31.7 kg CH-C ha for the AWD treatment and in the range 75.7-141.6 kg CH-C ha for the DF treatments. Correcting for field-to-field differences in CH production, the AWD practice reduced seasonal CH emissions 64.5 ± 2.5%. The AWD practice is increasingly implemented for water conservation in the U.S. Mid-South; however, based on this study, it also has great potential for reducing CH emissions.