Pesticides have long since killed not only plant pests, but also beneficial insects such as butterflies and bees, thus contributing significantly to the death of insects. The pesticide contamination is not only high during the spraying phases, but also exists throughout the entire year, as researchers have now discovered. The analyzes also showed that surrounding meadows were chronically contaminated with pesticides. The team is therefore urgently calling on politicians to take action.
More than 30 percent of Germany’s land area is used to grow crops. Pesticides have been applied to much of it several times a year since the 1970s. They are intended to control plant pests and weeds, but they also harm “innocents” such as butterflies, bees and earthworms. The large-scale use of pesticides has been proven to be involved in insect deaths, especially in cultivated landscapes. However, it is still largely unclear how long-term pesticides, once applied, will persist in plants, soil and the surrounding landscape.
A year full of pesticides
Researchers led by Carolina Honert from the Rhineland-Palatinate Technical University of Kaiserslautern-Landau have now examined pesticide contamination over the course of the year for the first time. To do this, the team monitored a total of nine fields in Rhineland-Palatinate where, among other things, vegetables and wine were grown. At each of these fields, the team took topsoil and vegetation samples several times a year at distances of one, five and twenty meters from the farmland. This enabled it to check whether adjacent meadows were also affected. Honert and her team then examined the various samples for residues of 93 common pesticides.
The result: Pesticides are apparently present in soil and plants not only during spraying phases, but all year round, as the analysis showed. Honert and her colleagues were able to detect up to 28 pesticides in the soil at the same time. On average there were ten. The plant samples contained an average of seven, and in some cases up to 25, different plant protection products, although there were seasonal fluctuations. Nevertheless: “We were able to show that complex mixtures of pesticides are present in low concentrations all year round. The effects of this chronic pollution of mixtures on the environment are largely unexplored,” explains Honert.
Quick action required
Also worrying: The researchers also detected pesticides that had not been applied during the year of the study. According to Honert and her team, this suggests that the pesticides take a very long time to break down in the environment. As already suspected, long-term pesticide contamination affected not only the fields themselves, but also the surrounding meadows. The team suspects that the harmful substances were probably carried there by the wind.
But pesticides can also be spread over much longer distances, emphasizes senior author Carsten Brühl: “In another study, we examined the spread of pesticides from apple cultivation in the valley in the Alps and were able to detect this even in mountain peak regions and protected areas. We have to assume that agricultural landscapes are chronically contaminated with pesticides.” In order to solve the problem, the researchers advocate reducing the use of pesticides by at least 50 percent as quickly as possible and instead relying on alternative cultivation methods. “We have to act now. Although the decline in biodiversity is pushed into the background by political decision-makers because it is less attractive in elections, the problem still exists and will negatively affect our livelihoods,” says Brühl.
Source: Rhineland-Palatinate Technical University of Kaiserslautern-Landau; Specialist articles: Scientific Reports, doi: 10.1038/s41598-024-84811-4