Sustainable Water Management for Irrigated Rice Production

Abstract

Water is necessary to offset the water requirement of rice crops,$\$nespecially under irrigated rice conditions (lowland, deepwater rice).$\$nInsufficient water supply during rice cultivation may obstruct the$\$nrice-growing rate and ultimate yield. On the other hand, anaerobic rice$\$nsystems emit methane (CH4), a greenhouse gas, and hence contribute to$\$nglobal warming. In this regards, introduction of aerobic rice systems$\$nmay be an option to reduce CH4 emissions and maintain water resources in$\$nthe ecosystem. In an effort to reduce CH4 emissions, the DNDC-rice model$\$nwas used to validate CH4 emissions under field conditions with various$\$nwater management regimes including continuously flooded, mid season$\$ndrainage, multiple drainage, and local farmer practice in the irrigated$\$nrice cultivation areas in Thailand. The results have shown lower CH4$\$nemissions from drainage fields than continuously flooded management.$\$nRelatively, longer field drainage presented a high potential for CH4$\$nreduction. Rice yields under four water managements were not$\$nsignificantly different; however, rice growth rate and water requirement$\$nwas dissimilar. The water consumption under mid season drainage$\$ntreatment was reduced by 5.3{%} and rice grain yield was increased by 5{%}$\$ncompared to conventional water management at the study site. The results$\$nfrom model simulation can explain the phenomenon of electron$\$ndonors/electron acceptors in rice soil. The contents of electron$\$nacceptors strongly affect CH4 emissions from rice fields, particularly$\$nunder alternative forms of water managements. The results from the field$\$nexperiment and modeling suggested field drainage during growing season$\$nas one option to mitigate CH4 emissions but maintain rice grain yield.