Organic-inorganic amendments regulate paddy soil redox properties and nutrient supply to enhance rice yield and nutrient use efficiency

Background and aims Rice, as the staple food for half of the global population, its yield improvement is crucial for ensuring food security. However, excessive application of chemical fertilizers has led to paddy soil degradation and reduced nutrient use efficiency, making it urgent to adopt reasonable improvement measures to achieve high and stable rice yield and sustainable soil utilization. Methods In this study, 8 treatments were set up: CK (no fertilization); NPK (chemical fertilizer alone); SD + NPK (soil replacement + chemical fertilizer); ST + NPK (straw + chemical fertilizer); C + NPK (biochar + chemical fertilizer); OM + NPK (organic fertilizer + chemical fertilizer); OM (organic fertilizer alone); and TI (technology integration). A systematic comparison was made on the effects of various improvement measures on paddy soil physicochemical properties and rice yield, aiming to provide theoretical basis and technical support for paddy soil cultivation and productivity improvement. Results OM + NPK reduced soil reductive substances, Fe²⁺, and Mn²⁺ to alleviate toxicity, optimized yield components, achieved the highest harvest index, and increased grain N/K accumulation (17.42%-19.42%). ST + NPK improved soil nitrogen, phosphorus, and supply capacity, boosted yields via more panicles, and cut costs. Both outperformed NPK alone, with OM + NPK as "high-yield/quality" and ST + NPK as "fertility/efficiency" models. Conclusion Organic-inorganic improvement regulates soil physicochemical properties and redox environment through organic carbon input, optimizes nutrient supply, and achieves a synergistic effect of increasing rice yield and improving soil quality. This provides a scientific basis for sustainable paddy field production and a feasible agronomic strategy to address food security challenges.