Enhancing rice yield, quality, and resource utilisation with slow-release fertiliser in alternate wetting and drying irrigation

Partial slow-release fertiliser substitution for urea combined with water-saving irrigation may synergistically improve rice yield, quality, water, and nitrogen (N) utilisation. A field experiment to evaluate different combinations of irrigation regimes: alternate wetting and drying irrigation (AWD) and flooding irrigation (FI), and N strategies: N0 (no N fertiliser); N1 (100% conventional fertiliser); N2 (100% SCF - sulphur-coated fertiliser); N3 (70% SCF + 30% urea), and N4 (50% SCF + 50% urea) on efficient rice production. Results indicated that higher substitution rates of SCF (N2 and N3) increased total N and ammonia N in surface water, leachate, and soil while reducing nitrate N relative to N1. The N3 strategy showed the highest yields, dry matter, total N uptake, and water N utilisation due to a nutrient release pattern that matched rice growth requirements. AWD yielded 5% lower than FI, except for the N3 strategy, but protein content increased by 12%, and amylose content dropped by 17%. The structural equation model analysis suggested that SCF positively impacted yield by influencing surface water total N and soil total N. Our findings indicate that implementing AWD alongside a 70% SCF basal fertiliser and 30% urea topdressing can optimise rice yield and quality while effectively managing water and fertiliser resources in the middle-lower Yangtze River Basin.