Soil microbial dynamics in a 120-year-long nutrient management experiment in a semi-arid Alfisol

We used metagenomic sequencing to compare effects of different nutrient amendment applications in a semi-arid Alfisol in India. We evaluated soil properties, microbiome community composition and abundance (bacteria, archaea, eukaryota), functional genes linked to carbon (C) and nitrogen (N) cycling, in the different nutrient conditions. We hypothesize that contrasting nutrient inputs impose legacy effects on soil biological and biochemical processes and regulate nutrient cycling efficiency and soil resilience-synthetic fertilizers, organic amendments, and INM could differentially shape microbial community composition, their associated nutrient-cycling genes, leading to distinct trajectories in soil fertility and health. Our specific objectives were: (1) to evaluate the effects of long-term nutrient management on soil attributes, microbial community composition and C and N cycling genes ; (2) to assess relationships among soil microbiome composition, C and N cycling genes and soil properties under contrasting nutrient management regimes; and (3) to characterize soil VOCs as functional indicators of microbiome-mediated biochemical processes. In summary, this study provides a theoretical and empirical basis for sustainable agricultural production and for designing nutrient management strategies that sustain soil health and agroecosystem resilience under intensive agricultural systems.