Impact of pesticides on soil health: identification of key soil microbial indicators for ecotoxicological assessment strategies through meta-analysis.

Pesticides remain a cornerstone of modern agriculture. Despite their key role, it is well documented that pesticides can have considerable off-target effects on a range of organisms. The effects of pesticides on soil health, and more importantly on soil microbiota, are currently not well addressed at the regulatory level, despite cumulative evidence for the pivotal role of the soil microbiota on ecosystem functioning. Here, we use a meta-analysis to assess the effects of pesticides on soil health parameters identifying key biological indicators for environmental risk assessment analysis. We demonstrate that ammonia oxidizing archaeal and bacterial amoA gene abundance were the most consistent indicators for pesticide exposure, with inhibition driven by herbicides and fungicides. Our meta-analysis, combined with their key functional role and the existence of well-standardized, high-resolution methods for monitoring their abundance, highlighted the potential of ammonia-oxidizing microorganisms (AOMs) as indicators of the toxicity of pesticides on soil microbiota. AOM could serve as drivers of chemical innovation in a "benign and sustainable by design" approach where new pesticide compounds will have to meet sustainability targets and ensure soil health preservation.