Continuous nutrient management practices for 40 years enhances soil carbon, enzymes and microbial indices in rice-wheat system

Soil aggregates serve as habitats of soil microbiome and directly influence on soil microbial nutrient demand and stabilization of organic matter. Evaluating the long-term impact of different nutrient management strategies on soil enzymatic stoichiometry and microbial indices within aggregates is essential for environmental significance. Hence, this study was planned to investigate the long-term biochemical changes occurring in the soil aggregates isolated through sieving methods under five nutrient management approaches: absolute control (no fertilizer or manure), 100% recommended dose of mineral fertilizer (NPK), 50% NPK + 50% N from farm yard manure (FYM), 50% NPK + 50% N from wheat cut straw (WCS) and 50% NPK + 50% N from green manure (GM) for rice; whereas, 100% NPK was applied to wheat in all treatments except absolute control. After 40 cycles of continuous rice-wheat cropping, the application of organic amendments along with chemical fertilizers significantly increased the proportion of macro-aggregates (Macro-A; >2 mm) while reducing micro-aggregates (Micro-A;