Insecticide residues in organic soils of six vegetable growing areas in Southwestern Ontario, 1976

Abstract

Abstract Organic soils on 28 farms located in six widely separated vegetable growing areas in southwestern Ontario were sampled in 197 6 and analyzed for insecticide residues. Soil organic content generally was >65%. Organochlorine insecticide residues were detected in soil on all farms. Total DDT ranged from <0.1 to 29 ppm. Dieldrin, endo‐sulfan, and endrin were present at levels up to 1.7, 1.8, and 0.9 ppm respectively. Organophosphorus insecticide residues were present in soil on 26 farms with ethion predominating (up to 7.8 ppm). Parathion, fonofos, and diazinon were present at levels as high as 2.5, 1.1, and 0.3 ppm respectively. Traces of dichlofenthion were detected on a few farms. Carbamate insecticides, mainly carbofuran, were found on ten farms, with one soil containing 8.7 ppm total carbofuran. Generally total‐DDT residues were highest>organophosphorus>cyclodiene>carbamate insecticide residues. Area averages of total insecticide concentration (ppm) in the six marshes were: Colbar 30.2, Holland 22.5, Keswick 12.7, Erieau 9.5, Leamington 9.1, and Thedford 7.7.