Assessing the feasibility of alternate wetting and drying (AWD) technique for improving water use efficiency in dry-season rice production

Alternate Wetting and Drying (AWD) Technique has effectively conserved water in various regions, particularly Asia. However, there is a lack of research on the feasibility of AWD in different paddy soil ecosystems, particularly in Cambodia. 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: safe AWD (AWD15), when the perched water table drops to 15 cm below the soil surface, and mild AWD (AWD20), when it drops to 20 cm below the soil surface. Five field experiments were conducted from 2021 to 2023. Associative causal relationships between measurable and latent variables of rice grown under CF and AWD were tested using partial least squares structural equation modeling (PLS-SEM) and an analysis of variance (ANOVA).Our results showed that safe and mild AWD did not significantly affect grain yield, yield components, harvest index (HI), and root growth compared to conventional flooding (CF). Despite similar yields, AWD significantly reduced total water inputs by 10–30% in AWD15 and 22–24% in AWD20 compared to CF. Among the AWD treatments, AWD15 exhibited the highest WUE. Our study found that on sandy loam soil, both AWD15 and AWD20 treatments improved WUE over CF, and clay soil’s WUE was higher than sandy soil. However, clay soil’s WUE in AWD did not improve over CF. Our findings demonstrate that implementing safe and mild AWD has significant potential for rice growing on sandy loam.