Agronomic Efficiency and Yield Responses to Rainfall and Temperature Variability under Integrated Nutrient Management Practices for Rice-Wheat Cropping

Climate-Resilient Nutrient Management in Rice–Wheat Cropping System

Abstract

Sustainable rice-wheat production requires nutrient-management strategies that maintain soil fertility and crop productivity while reducing dependence on mineral fertilizers and improving crop responses to climatic variability. A long-term field experiment evaluated the effects of biomass supplementation with an opportunity legume (Vigna radiata; LE), green manure (Sesbania aculeata; GM), farmyard manure (FYM), wheat straw (WS) and rice straw (RS) under reduced mineral fertilizer inputs in a rice-wheat cropping system. Ten years of weather data were classified into rainfall-deficit and rainfall-excess years and above- and below-average temperature years for rice and wheat separately. Relationships between C return to soil and crop yield and fertilizer-N-use efficiency were evaluated under contrasting climatic conditions. Biomass supplementation substantially increased soil C accumulation and C return. Green manuring recorded the highest soil C stock (3450 ± 270 g m–²), C assimilation (20.6 ± 1.3 t ha–¹) and C return (69.9 ± 0.4 t ha–¹). Plant available N was also substantially enhanced by biomass-based management; in rice it reached 231 ± 5 μg cm–² under RS, while in wheat the highest value was 827 μg cm–² under full mineral fertilization. During rainfall-deficit years, several biomass treatments maintained relatively stable grain yield despite increased C return, particularly LE in rice and LE, GM and WS in wheat, indicating greater nutrient sufficiency. Under rainfall-excess conditions, biomass C was more closely associated with crop yield, particularly in wheat. Below-average temperature conditions also favored wheat grain production, whereas above-average temperatures reduced productivity. Long-term biomass supplementation enhanced soil C and nutrient availability and enabled rice-wheat crops to maintain productivity under variable rainfall and temperature conditions with reduced mineral fertilizer inputs, suggesting a strong potential of biomass-based nutrient management to improve nutrient security, fertilizer-N-use efficiency and climate adaptability of intensive rice-wheat systems.