Plant–microbe networks in soil are weakened by century‐long use of inorganic fertilizers

Summary

This long-term field study from Rothamsted Research examined how a century of inorganic nitrogen fertilisation altered the ecological networks between plants and soil microorganisms in permanent grassland. Both plant and microbial community diversity declined significantly, alongside reductions in genes involved in carbon, nitrogen and phosphorus cycling. Critically, the structural complexity of plant–microbe networks weakened substantially, with reduced connectivity and association strength, suggesting that sustained inorganic fertilisation may compromise soil ecosystem resilience and functional stability.

UK applicability

These findings are directly applicable to UK grassland management, particularly for farms relying on long-term inorganic fertiliser inputs. The research suggests that current nitrogen fertilisation practices may erode soil biological complexity and nutrient cycling capacity, with implications for soil health monitoring and the case for diversified nutrient management strategies.

Key measures

Plant species richness and diversity; soil microbial richness and diversity; microbial functional genes (C, N, P cycling); network node numbers; network connectivity; network density; clustering coefficient; microbial association strength; soil carbon and nitrogen content

Outcomes reported

The study measured changes in plant and soil microbial community richness, diversity, and functional gene expression in response to >150 years of fertilisation treatment. Network complexity metrics (node numbers, connectivity, density, clustering) between plants and microbial communities were quantified using GeoChip molecular detection.

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