Small-grain cover crops have limited effect on neonicotinoid contamination from seed coatings

Authors: PEARSON, KIRSTEN - Pennsylvania State University; ROWEN, ELIZABETH - Pennsylvania State University; Elkin, Kyle; WICKINGS, KYLE - Cornell University; SMITH, RICHARD - University Of New Hampshire; TOOKER, JOHN - Pennsylvania State University

Submitted to: Journal of Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/14/2021
Publication Date: 3/22/2021
Citation: Pearson, K.A., Rowen, E.K., Elkin, K.R., Wickings, K., Smith, R.G., Tooker, J.F. 2021. Small-grain cover crops have limited effect on neonicotinoid contamination from seed coatings. Journal of Environmental Science and Technology. 55:4679-4687. https://doi.org/10.1021/acs.est.0c05547.
DOI: https://doi.org/10.1021/acs.est.0c05547

Interpretive Summary: The advent of new pest control insecticides has been a positive on many fronts including greater harvest yields. Known as a systemic pesticide, plants can absorb these insecticides which can be used as a less farming intensive biological control method against insects that damage these crops. Since their commercialization however, there has been negative press overshadowing their utility. One of these negative issues is the ability for the pesticide residues to persist in the soil long after the active ingredient has degraded. Analysis of soil samples receiving neonicotinoid treatments support this idea and suggest that not only are these persistent residues found in treated fields, but are also transported to fields that have not been treated.

Technical Abstract: Neonicotinoids from insecticidal seed coatings can contaminate soil in treated fields and adjacent areas, posing a potential risk to nontarget organisms and ecological function. To determine if cover crops can mitigate neonicotinoid contamination in treated and adjacent areas, we measured neonicotinoid concentrations for three years in no-till corn-soybean rotations, planted with or without neonicotinoid seed coatings, and with or without small grain cover crops. Although neonicotinoids were detected in cover crops, high early season dissipation provided little opportunity for winter-planted cover crops to absorb significant neonicotinoid residues; small grain cover crops failed to mitigated neonicotinoid contamination in either treated or untreated plots. As the majority of neonicotinoids from seed coatings dissipated shortly after planting, residues did not accumulate in soil, but persisted at concentrations below 5 ppb. Persistent residues could be attributed to historic neonicotinoid use and recent, nearby neonicotinoid use. Tracking neonicotinoid concentrations over time revealed a large amount of local interplot movement of neonicotinoids; in untreated plots, contamination was higher when plots were less isolated from treated plots.