Assessing the Feasibility of Alternative Wetting and Drying (AWD) Technique for Improving Water Use Efficiency in Dry-Season Rice Production

Abstract AWD has been effective in conserving water in various regions, particularly in Asia. However, there is a lack of research on the feasibility of AWD in different paddy soil ecosystems. We evaluate the possibility of saving water in dry rice production in Cambodia by quantifying the effects of AWD on rice yield and water use efficiency (WUE) with varying varieties and soil properties. We tested AWD at two different threshold levels: AWD15, when the perched water table drops to 15 centimeters below the soil surface, and AWD20, when it drops to 20 centimeters below the soil surface. Five field experiments were conducted from 2021 to 2023. Our results showed that AWD did not significantly affect grain yield, yield components, HI, and root growth compared to conventional flooding (CF). However, AWD did improve WUEs when considering soil properties. WUE was not improved in AWD when the top soil was sandy clay loam. Despite similar yields, AWD significantly reduced total water inputs by 10-30% in AWD15 and by 22-24% in AWD20 compared to CF. Among the AWD treatments, AWD15 exhibited the highest WUE. The finding demonstrates that safe and mild AWD has potential for rice growing on sandy loam, and WUE could be improved further in AWD when implemented on soil with low saturated conductivity, regardless of its texture.