PubMed · 2026-06-13
A 116-year field experiment in semi-arid India found that adding compost or manure to soil builds far richer, more active microbial communities than synthetic fertilizers alone — communities that cycle carbon and nitrogen more effectively and sustain soil fertility over the long run in ways chemical inputs cannot replicate.
After 116 years, organic amendment plots had significantly higher soil organic carbon, microbial biomass, and enzyme activity than synthetic-fertilizer-only plots.
Organic inputs shifted soil communities toward nutrient-loving copiotrophic microbes and enriched nitrogen-fixation and carbon-fixation genes, while synthetic-fertilizer plots were dominated by stress-tolerant oligotrophs with weaker biological nutrient pathways.
Integrated nutrient management (organic plus inorganic inputs combined) produced the most diverse soil volatile organic compounds, which were strongly correlated with soil organic carbon levels and overall biological activity.