Pesticide use has propelled agriculture to new heights of productivity. However, they’re also eating away at farmlands.

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Over the last 50 years or so, phytosanitary products have enjoyed wider and wider use in agriculture, especially across developed countries. This helped to bring productivity to levels unheard-of before — but, at least in the European Union, it also degraded the soils.

Putting the ‘pest’ in ‘pesticide’

A duo of scientists participating in the Diverfarming project at the University of Wageningen, Netherlands, report finding traces of pesticide compounds in European agricultural soil samples. Researchers Violette Geissen and Coen J. Ritsema retrieved and analyzed 317 samples of surface agricultural soils from 11 countries in Europe. The soils used in this study belonged to 6 different cropping systems.

All in all, 83% of the samples contained traces of pesticides; the range of such compounds was also pretty impressive — 76 different types of pesticides were identified in the samples. Roughly 58% of that percentage were mixes of pesticides, while the rest (25%) came from a single type of substance. Glyphosate, DDT (banned since the 1970s,) and broad-spectrum fungicides were the main compounds detected.

The discussion around pesticide use revolves roughly around two key themes: the surprising persistence of such compounds in the soil (which this study indicates) and their toxicity to non-objective (non-target) species. Considering that the team worked with surface soil samples specifically, the results point to the ease with which such compounds can become airborne due to air currents.

The Diverfarming project proposes a more rational use of land and other elements of agriculture — water, energy, fertilisers, machinery, and pesticides — to address this issue. Diverfarming is a project financed by the Horizon 2020 Programme of the European Commission, within the challenge of “Food Security, Sustainable Agriculture and Forestry, Marine, Maritime and Inland Water Research and the Bioeconomy,” which draws expertise from members in virtually every country in the Union.

The paper proposes a series of alternatives to current practices in agriculture to help preserve the soil microorganism balance and, by extension, its biodiversity and overall health. These range from the use of new non-persistent pesticides, bio-stimulants, organic composts, or crop diversification — which contributes to balanced insect communities and thus to the absence of pests.

According to the study, the presence of mixes of pesticide residues in the soil is more the rule than the exception, which illustrates the need to evaluate environmental risks in the case of these combined compounds to minimise their impact. The effects of such mixes on the soil need to be investigated further, the team reports.

The paper “Pesticide residues in European agricultural soils – A hidden reality unfolded” has been published in the journal Science of The Total Environment.