Abstract
Considering that pesticides have been used in Europe for over 70 years, a system for monitoring pesticide residues in EU soils and their effects on soil health is long overdue. In an attempt to address this problem, we tested 340 EU agricultural topsoil samples for multiple pesticide residues. These samples originated from 4 representative EU case study sites (CSS), which covered 3 countries and four of the main EU crops: vegetable and orange production in Spain (S-V and S-O, respectively), grape production in Portugal (P-G), and potato production in the Netherlands (N-P). Soil samples were collected between 2015 and 2018 after harvest or before the start of the growing season, depending on the CSS. Conventional and organic farming results were compared in S-V, S-O and N-P. Soils from conventional farms presented mostly mixtures of pesticide residues, with a maximum of 16 residues/sample. Soils from organic farms had significantly fewer residues, with a maximum of 5 residues/sample. The residues with the highest frequency of detection and the highest content in soil were herbicides: glyphosate and its main metabolite AMPA (P-G, N-P, S-O), and pendimethalin (S-V). Total residue content in soil reached values of 0.8mgkg-1 for S-V, 2mgkg-1 for S-O and N-P, and 12mgkg-1 for P-G. Organic soils presented 70-90% lower residue concentrations than the corresponding conventional soils. There is a severe knowledge gap concerning the effects of the accumulated and complex mixtures of pesticide residues found in soil on soil biota and soil health. Safety benchmarks should be defined and introduced into (soil) legislation as soon as possible. Furthermore, the process of transitioning to organic farming should take into consideration the residue mixtures at the conversion time and their residence time in soil.
Highlights
Farming systems in Europe rely strongly on the use of pesticides to secure yields in plant production and animal husbandry, with farmers using an average of 340,000 to 370,000 tons of active substances annually (FAOSTAT, 2019)
Since none of the parties interviewed for this study reported that glyphosate was applied in SeV, it was not analysed in those samples
In NePeC, farmers applied mainly herbicides, in PeG and SeVeC mainly fungicides, and in SeOeC mainly insecticides. 44e55% of the active substances applied in the case study sites (CSS) are non-persistent, 26e36% moderately persistent, 0e24% persistent and 4e11% very persistent (Table 2)
Summary
Farming systems in Europe rely strongly on the use of pesticides to secure yields in plant production and animal husbandry, with farmers using an average of 340,000 to 370,000 tons of active substances annually (FAOSTAT, 2019). Of the 487 active substances approved for sale in the EU market (EC, 2020a), almost 50% are bioaccumulative, 25% are persistent in soil (DT50 > 100 days; PPDB, 2020), 30% have a high acute aquatic toxicity, and 28 are suspected carcinogens (EC 2008a). These and other related figures raise serious concerns about the impact of pesticides on the health of ecosystems, animals and humans. Scientists have discussed the idea that pesticide use is one of the main reasons for the decline of beneficial insects and pollinators (Hallmann et al, 2017), scientific knowledge about the effects of mixtures of pesticides with different modes of action remains very limited
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