European Study Finds Pesticide Cocktails Present in Soils after Decades of Use

A European study published in Environmental Pollution reports on the results of testing for pesticide residues from historic use on both conventional and organic farms in three different countries. Soils from conventional farms presented mostly mixtures of pesticide residues, with a maximum of 16 residues per soil sample. Soils from organic farms had significantly fewer residues, with a maximum of five residues per soil sample. The residues with the highest frequency of detection and the highest content in soil were herbicides: glyphosate and pendimethalin. Organic soils presented 70–90% lower residue concentrations than the corresponding conventional soils. The scientists note that 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. They also recommend that the process of transitioning to organic farming should take into consideration the residue mixtures at the conversion time and their residence time in soil.