ABSTRACT Alternate wetting and drying (AWD) irrigation alleviates prolonged flooding‐induced soil redox potential decline and methane emissions in rice paddies. AWD typically maintains a 15 cm water table depth. While straw incorporation intensifies soil reduction under prolonged flooding, the optimal intensity of AWD under straw incorporation remains unclear. We conducted a field experiment in northeast China comparing two AWD regimes (AWD15 and AWD20, draining to 15/20 cm depth) with straw incorporation. Soil reductive substance content, root activity, tillering dynamics and yield were systematically monitored. The results demonstrated that compared with AWD15, the AWD20 treatment significantly reduced the content of soil reductive substances, with a 22.6% and 42.7% decrease in soil Fe 2+ and Mn 2+ content, respectively, and an 80.9% and 82.7% decrease in total reductive matter content and active reductive matter content, respectively, at mid‐season drainage. The soil Fe 2+ content was negatively correlated with the redox potential of the soil. After rewetting, AWD20 treatment significantly increased soil microbial biomass carbon (MBC) and nitrogen (MBN) content. Compared with the AWD15 treatment, only the number of tillers decreased by 4.8% in the AWD20 treatment, while there was no statistical difference in rice root activity, effective spike number, carbon and nitrogen content of rice, nitrogen fertiliser partial factor productivity (PFP), harvest index, yield and yield stability. The findings suggest that AWD20 holds promise as a sustainable irrigation strategy for straw‐incorporated rice systems, contributing to improved plant growth conditions and enhanced field sustainability.
Li et al. (Thu,) studied this question.