Soil microbiome signatures are associated with pesticide residues in arable landscapes

Summary

This field-based ecological study assessed how pesticide residues persisting in agricultural soils associate with soil microbiome structure and function across 60 arable fields under three management regimes. Although environmental factors (climate, geography, soil properties) remained the dominant drivers of microbiome composition, pesticide residues emerged as the strongest management-related factor shaping microbial communities, outweighing effects of cropping system alone. The findings reveal complex community-level responses: pesticide residues were predominantly associated with increased relative abundance of specialist degrader taxa (113 bacterial and 130 fungal), but negatively correlated with bacterial diversity and the functional gene nifH (essential for biological nitrogen fixation), suggesting potential long-term consequences for soil ecosystem services in contaminated arable systems.

UK applicability

These findings are directly relevant to UK arable farming, where pesticide residues persist widely in conventional and no-tillage systems. The results suggest that existing UK pesticide regulation based on acute toxicity testing may not adequately capture subtle, long-term effects on soil microbial function and nutrient cycling capacity; policymakers and agronomists should consider microbiome-informed risk assessment and the potential benefits of pesticide reduction strategies for maintaining soil health.

Key measures

Pesticide residue concentrations (48 compounds); soil microbiome composition and diversity (bacterial and fungal amplicon sequencing); abundance of nifH gene (nitrogen fixation); soil physico-chemical properties; climate and geographic variables; management system (conventional, no-tillage, organic)

Outcomes reported

The study characterised associations between 48 widely-used pesticide residues and soil microbiome traits (bacterial and fungal community composition, diversity, and functional genes) across 60 fields under three management systems. Pesticide residues showed stronger associations with microbiome signatures than cropping system management, with differential effects on bacterial versus fungal communities and nitrogen-fixation capacity.

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