Pesticides of all types pose a clear risk to organisms living in soil and that play a key role in food sustainability and carbon storage, a major new report has found.
Researchers in the US reviewed 400 different studies, looking at 275 unique species and 284 different pesticides, to place new emphasis on the impact of these chemicals on soil.
The results, published this week in the journal Frontiers in Environmental Science, found that “pesticides of all types pose a clear hazard to soil invertebrates. Negative effects are evident in both lab and field studies, across all studied pesticide classes, and in a wide variety of soil organisms.”
Previous work on the impact of pesticides has focused on water and air, as runoff and pesticide drift are the most significant sources of offsite pesticide movement, researchers said.
But pesticides are often applied directly to soil as drenches and granules, and increasingly in the form of seed coatings, making it important to understand how pesticides impact soil ecosystems.
Soil is home to some of the most complex biodiversity on Earth, with a typical sample comprising hundreds of thousands of macroinvertebrates and nematodes, as well as microorganisms, and bacterial species.
“Soils contain an abundance of biologically diverse organisms that perform many important functions such as nutrient cycling, soil structure maintenance, carbon transformation, and the regulation of pests and diseases,” the researchers wrote.
Soil biodiversity helps these ecosystem functions continue, while burrowing activity aerates soil and increases water retention. Earthworms alone can construct up to 8,900 km of channels per hectare, decreasing soil erosion by 50 per cent via increased soil porosity and water infiltration, the study said.
Researchers concluded that the prevalence of negative effects highlights how soil and soil life should be considered within any risk assessment for pesticides.