Closing the rice production trilemma: AWD and nitrogen-loaded biochar synergy achieves co-benefits in yield improvement, water saving, and ammonia mitigation

Abstract Current rice production faces a critical trilemma of ensuring food security while conserving water and mitigating climate impacts. Conventional irrigation and nitrogen application sustain yields but simultaneously exacerbate water scarcity and environmental burden. Addressing this challenge requires urgently reconciling trade-offs among food security, water conservation, and climate regulation through optimized water and nitrogen management. Here, a two-year field experiment was conducted to evaluate the effects of alternate wetting and drying irrigation (AWD) and nitrogen-loaded biochar (NLB, 20 t ha −1 ) on rice yield, water consumption, ammonia volatilization, and nitrogen distribution along the “soil–rice–plant” continuum. We found that AWD significantly reduced water consumption by 14.17–15.56% and increased rice yields by 2.23–5.11% compared to continuous flooding irrigation (CF). Notably, NLB addition under AWD further enhanced yields by 6.70–12.55% and reduced water use by 6.81–12.37% relative to the non-NLB control. Although NLB alone increased ammonia volatilization, this effect was mitigated by 11.38% when combined with AWD compared with CF. PLS-PM revealed that both NLB and AWD significantly and directly increased rice nitrogen accumulation and optimized water consumption, jointly contributing to yield gains. In conclusion, the AWD and NLB synergy is a next-generation strategy with the promise to simultaneously safeguard food security, lower environmental burden, and minimize water use—a triple win unattainable with conventional practices. These findings offer a scalable and replicable framework for sustainable rice production aligned with Sustainable Development Goals (SDGs) 2 (Zero Hunger), 6 (Clean Water), and 13 (Climate Action). Highlights Nitrogen-loaded biochar (NLB) was applied in alternate wetting and drying irrigation (AWD) paddy fields. NLB and AWD synergy significantly enhanced rice grain yield, reduced water consumption, and mitigated ammonia volatilization compared to each strategy alone. The enhanced rice nitrogen accumulation and optimized water consumption contribute to the yield improvement under NLB and AWD applications. Graphic Abstract