Long-term assessment of diverse nutrient management strategies in a rice-rice cropping system: analyzing yield trends, resource use efficiency and economic viability over a sixteen-year period

In recent times, the sustainability of rice-rice cropping systems has been threatened by a yield plateau, high input cost, declining water and labor availability, and increasing food demand. Hence, the rice-based cropping systems seek more attention in relation to nutrient management. This study evaluated the impact of 16-year long-term fertilizer application on crop and water productivity, yield trend, nutrient use-efficiency, and profitability of a rice-rice system (eight treatments and four replications; randomized block design). The study showed that the integrated application NPK and FYM (BInOF) significantly increased grain yield up to (similar to 3949 kg ha(-1)) and benefit cost ratio (2.01 and 1.62) in monsoon and winter rice. Furthermore, organic manure along with inorganic fertilizers significantly increased the nutrient uptake up to (80-89 kg ha(-1) N; similar to 16-19 kg ha(-1) P; similar to 85-106 kg ha(-1) K; 0.22-0.25 kg ha(-1) Zn) in monsoon and winter rice. The largest N recovery was observed under BInOF plots (54.9 to 59.8%). The highest carbon sequestration (2.06 t ha(-1) after 16 years of cultivation) and water productivity (3.5-4.5 kg grain ha-mm(-1)) was observed under BInOF system (NPK + FYM). The sustainable yield index (SYI, 0.7), an indicator of rice sustainability was highest in BInOF. This study offers valuable insights into the impacts of chemical fertilizers and organic manures on the sustainability of the rice-rice cropping system. Such findings can guide policymakers in formulating strategies for crop diversification and underscore the importance of incorporating organic matter for optimal crop performance.