• A new study found pesticide residues in 70% of soil samples across 26 European countries, making contamination the second-strongest factor shaping soil biodiversity after basic soil properties.
• The pesticides severely harmed beneficial organisms like mycorrhizal fungi and nematodes that help plants absorb nutrients, and disrupted critical soil functions, including phosphorus and nitrogen cycling.
• Pesticide contamination extended beyond farmland into forests and grasslands where pesticides aren’t applied, likely due to spray drift, with some chemicals persisting in soil for years.
• Researchers say current regulations are inadequate because they test pesticides on only a few individual species rather than examining effects on entire soil communities and the ecosystem functions they perform.

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For farmers, sometimes the easiest way to save a crop or prevent catastrophic insect damage is to spray a pesticide. But this common practice is wreaking havoc on the soil, according to new research published recently in the journal Nature.

The study examined soil from 26 European countries, finding that pesticide contamination is widespread beyond agricultural lands and substantially damages the beneficial soil organisms essential for healthy ecosystems.

Researchers found pesticide residues in 70% of the 373 soil samples collected from agricultural fields, grasslands and forests. The contamination emerged as the second-strongest factor shaping soil biodiversity patterns, surpassed only by basic soil properties like texture and pH.

“This contamination has a major impact on various beneficial soil organisms, such as mycorrhizal fungi and nematodes, impairing their biodiversity,” Marcel van der Heijden, a professor at the University of Zurich’s Department of Plant and Microbial Biology and one of the study’s lead authors, said in a statement.

Mycorrhizal fungi form partnerships with the roots of plants and generally help plants obtain minerals and water from soil. Image by Wilhelm Zimmerling PAR via Wikimedia Commons (CC BY-SA 4.0).

Mycorrhizal fungi, which form partnerships with plant roots to help crops absorb water and nutrients, were among the organisms most affected by pesticide exposure. The fungicide bixafen, commonly used to combat harmful fungi on cereal crops, proved especially damaging to multiple types of soil organisms studied.

The harmful effects of pesticides on birds, bees and other insects have been well documented. However, impacts on soil microorganisms remains poorly understood, according to the study’s authors, who write that their research provides the first comprehensive quantitative evidence of pesticide impacts on European soil life.

The researchers examined how 63 commonly used pesticides affected soil archaea, bacteria, fungi, protists, nematodes and arthropods, revealing what they describe as “complex and widespread” impacts on soil microorganisms.

Fungicides (pesticides used to eliminate fungi) were the most frequently detected compounds in soil samples, accounting for 54% of all active ingredients found. Herbicides (pesticides aimed at plants) made up 35%, while insecticides represented 11%. The herbicide glyphosate was the single most common active ingredient detected.

While agricultural fields contained the highest pesticide concentrations, researchers also discovered contamination in forests and meadows where pesticides are not normally applied, which they say is likely due to spray drift from nearby treated areas.

Nematodes are tiny, worm-like organisms that play an important role in the soil nutrient cycle. Image by Vyzhdova V. via Wikimedia Commons (CC BY-SA 4.0).

Researchers from 10 institutions participated in the study, including the European Union’s Joint Research Centre, the University of Vigo in Spain and Swiss agricultural research institute Agroscope. They say that pesticides fundamentally altered soil communities.

“Some soil organisms, especially various types of bacteria, benefit from the use of pesticides, probably because other organisms are reduced,” said Julia Königer from the University of Vigo, the study’s first author.

Beyond changing which organisms live in soil, pesticides also disrupted critical soil functions. By examining key genes involved in nutrient cycling, researchers demonstrated that pesticide residues interfere with how soil processes phosphorus and nitrogen.

“This suggests that the natural function of the affected soil is reduced, and additional fertilization is necessary to maintain yields,” van der Heijden said.

The persistence of some pesticides makes the problem worse. Because certain chemicals break down slowly, they can remain in soil for years after application, creating long-term impacts on soil ecosystems.

“Our study shows that pesticides represent a very significant human environmental impact on our soils,” said Maria J.I. Briones from the University of Vigo, who co-led the study. “Often, people don’t even consider the extent of the effects of pesticides on non-target organisms.”

The researchers found the soil impacts of pesticide use extended beyond agricultural land. Image by Winniepix via Flickr (CC BY 2.0).

Healthy soil biodiversity is foundational to healthy ecosystems. Soils store more carbon than the atmosphere and all plant and animal life combined, making them essential for climate regulation. They also support food production, control erosion and regulate water resources.

“Because of its central role in supporting essential ecosystem services, the importance of protecting soil biodiversity on both natural and working lands cannot be overstated,” Daniel Rath, a soil scientist at the Natural Resources Defense Council who was not involved in the study, told Mongabay.

The researchers write that current pesticide regulations are not strong enough to protect biodiversity. They say that, currently, regulators test pesticides on only a few species, such as a single earthworm species, one nematode species and one collembolan species, and measure limited endpoints like the rates at which pesticides break down into smaller compounds.

To better safeguard soil biodiversity, the study authors say regulators should examine how pesticides affect whole communities of soil organisms and the critical functions they perform, such as nutrient cycling and carbon storage.

Banner image: Soil-dwelling springtails – tiny, insect-like arthropods of the class Collembola – are vulnerable to pesticides. Image by Alandmanson via Wikimedia Commons (CC BY-SA 4.0).

Liz Kimbrough is a staff writer for Mongabay and holds a Ph.D. in ecology and evolutionary biology from Tulane University, where she studied the microbiomes of trees. View more of her reporting here.

Citation:

Köninger, J., Labouyrie, M., Ballabio, C., Dulya, O., Mikryukov, V., Romero, F., … & van der Heijden, M. G. A. (2026). Pesticide residues alter taxonomic and functional biodiversity in soils.Nature, 1-7.

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