Abrupt versus gradual application of pesticides: effects on soil bacterial and fungal communities

Summary

This laboratory study examined how the timing of pesticide application—abrupt versus gradual—influences soil microbial communities, particularly focusing on ten commonly used pesticides. Whilst bacterial communities showed minimal response, fungal communities exhibited strong selective pressure under gradual exposure, with rare taxa proliferating and community evenness increasing, particularly for herbicides and triazole fungicides. The findings suggest that prolonged pesticide exposure exerts stronger selective pressures on soil fungi than transient application, potentially affecting fundamental soil functions such as nutrient cycling and decomposition.

Regional applicability

The study is a controlled laboratory experiment with no specified geographic origin, limiting direct applicability to UK field conditions. However, since the ten pesticides tested are likely to include compounds authorised for use in UK agriculture, the findings regarding fungal community sensitivity to herbicides and fungicides are relevant to understanding potential long-term impacts of UK pesticide use practices on soil health.

Key measures

Microbial diversity, fungal and bacterial community composition, relative abundance of fungal taxa, community evenness, high-throughput sequencing data

Outcomes reported

The study measured microbial diversity and community composition in soil bacterial and fungal communities exposed to ten commonly used pesticides under two application regimes (abrupt versus gradual) using high-throughput sequencing. Key findings included differential responses between bacterial and fungal communities, with fungi showing strong responses to pesticide exposure and gradual application promoting increased community evenness.

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