Soil covers this month’s front page of the science journal Nature, headlining with: “Down to Earth - How pesticides reshape soil biodiversity”. The cover refers to the recently published extensive research of an international team of researchers: “Pesticide residues alter taxonomic and functional biodiversity in soils” [1].
Soils host about 59% of Earth’s biodiversity. [2] Soil life is essential for soil and wider ecosystem functions, and for our subsistence. Soil organisms provide critical functions such as plant growth, food production, water purification, buffering and storage, and carbon storage. The harmful impacts of pesticides on soil biodiversity, threatening ecosystem health, have been demonstrated in scientific literature. We dug into the topic in our recent earlier blog, celebrating World Soil Day. [2]
The impressive continent-wide work by Köninger & Labourie et al. provides further key evidence on the effects of pesticides on soil biodiversity. The study investigated the effects of pesticides found on soil archaea, bacteria, fungi, protists, nematodes, arthropods,key functional groups and functional gene groups. The effects were assessed across 373 study sites, comprising annual croplands, permanent croplands, former croplands recently converted to grasslands, extensive grasslands and woodlands, in 26 European countries.
Key findings of the study
- The presence of pesticides were found to be, after soil properties, the second widest driver of soil biodiversity patterns
- At 70% of the sites, one or more pesticide residues were found. In total, 63 different pesticides were detected
- The majority of pesticides detected were fungicides (54%), followed by herbicides (34.9%) and insecticides (11.1%)
- While highest numbers of residues were, as expected, found in croplands, pesticides were also present in the other sites. Associations between pesticides and soil biodiversity were consistent among analyses for croplands and other sites.
- Pesticides alter microbial functions, including nitrogen and phosphorus cycling
- Pesticides negatively impact beneficial soil taxa, such as:
- arbuscular mycorrhizal fungi (AMF), which are fungi that form symbiotic relationships with the roots of plants. They, among more, enhance plants’ uptake of water and nutrients, and protect plants against pathogens
- bacterivore nematodes, which have been found to enhance microbial activity, nutrient and carbon cycling and plant growth, and regulate microbial composition, pollutant breakdown and pests. [3]
- Increasing concentrations of certain fungicides were found to reduce richness and diversity of archaea, bacteria, protists, nematodes and arthropods.
- On the other hand, soil organisms harmful to plant growth, e.g. fungal plant pathogens, herbivore nematodes and protist plant parasites, were positively affected by increased concentration of certain pesticides, such as the herbicides pendimethalin and glyphosate.
- The study results suggest that bacteria may be favoured in pesticide-rich environments, whereas fungal communities decline.
- Certain pesticides were found to affect specific functional capacities of soil biota. For example, carbendazim, AMPA and bixafen decreased the diversity of nitrogen and phosphorus-related genes. This points at the microbial nitrogen metabolism and phosphorus uptake being especially vulnerable to pesticides.
The researchers highlight the need to better represent the broader ecological impact of pesticide use on soil life in EU risk assessment procedures, and move towards a more holistic approach.
The current procedures:
- Primarily focuses on single substances tested on a few invertebrate species, with specific endpoints, and do not consider a wide range of field conditions and the effects of long-term exposure
- Overlook key groups such as AMF and diverse microbial communities
- Use a NOEC (no observed effect concentration) which is solely based on a limited number of soil invertebrate species, and does not capture the complexity of the responses of field communities
The authors underline that:
- To protect soil ecosystems, ecotoxicological assessments must move beyond single-species tests, and include community-level and functional responses
- As pesticides drift into non-agricultural areas, again confirmed in this study, the researchers recommend refining environmental risk assessment and regulations to consider off-site pesticide effects
- Further research must focus on systematically integrated pesticide use and monitoring data, including from areas beyond cropland, to improve assessment of the broader exposure and potential impacts of pesticides. Transparent pesticide use data and environmental assessments across diverse ecosystems are needed.
- Threshold values for pesticide impacts on a wider range of soil biota should be established, across land use intensity gradients, soil types and climates
- We need to invest in sustainable pest managements solutions and agro-ecological practices which support productivity and soil health
The need to improve pesticide risk assessment
The need to improve pesticide risk assessment has been called for repeatedly by experts, and has been central in recommendations of key EU research projects focusing on pesticides, such as the EU Sprint project. [4]
These calls are in stark contrast with the Commission’s current proposal for a “food and feed safety” omnibus, to seriously weaken current pesticide authorisation and risk assessment. [5] For example, the proposal introduces the unlimited approval of pesticides as the default, and undermines the requirement to always use most recent scientific evidence when authorising pesticide products at the national level. These proposals, rather than closing the loopholes in risk assessment, seriously threaten the EU’s ability to protect soil and overall biodiversity, ecosystem functioning and citizens’ health. The scientific community responded to the proposal, by highlighting the urgent need to better protect against harmful pesticides. [6]
Notes:
[1] Königer et al. (2026). Pesticide residues alter taxonomic and functional biodiversity in soils
[2] Anthony et al. (2023) - Enumerating soil biodiversity
[2] Blog: Let’s celebrate World Soil Day: Protect soils against pesticides!
[3] Trap et al. (2015). Ecological importance of soil bacterivores for ecosystem functions, Trap et al. (2025). Ecosystem functions supported by soil bacterivorous nematodes
[4] Key messages Sprint project
[5] Food and feed safety omnibus’ threatens EU pesticide rules
[6] Scientific Statement on Pesticides in the Omnibus
