INSECTICIDE RESIDUES IN POTATOES AND SOIL AFTER CONSECUTIVE SOIL TREATMENTS OF ALDRIN AND HEPTACHLOR

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Abstract
Aldrin or heptachlor at 5 and 10 lb per acre were each incorporated into a sandy loam soil in 1958, 1959, and 1960. In 1963 the soils and potatoes grown therein were analyzed for insecticide residues by electron capture gas chromatography.Soils which had received applications of heptachlor contained appreciable amounts of gamma-chlordane in addition to heptachlor and heptachlor epoxide. Gamma-chlordane, a constituent of commercial formulations of heptachlor, was more persistent in soil than heptachlor, and the heptachlor/gamma-chlordane ratio decreased with time. Soils to which a total of 30 lb/acre of commercial heptachlor had been added were found to contain up to 2.1 p.p.m. gamma-chlordane, 2.0 p.p.m. heptachlor, and 0.8 p.p.m. heptachlor epoxide. Soils treated with the same amount of aldrin contained up to 0.8 p.p.m. aldrin and 2.3 p.p.m. dieldrin.Potatoes grown in these soils contained up to 0.017 p.p.m. heptachlor, 0.06 p.p.m. heptachlor epoxide, 0.016 p.p.m. gamma-chlordane, 0.002 p.p.m. aldrin, and 0.03 p.p.m. dieldrin of the total fresh weight. Heptachlor, aldrin, and gamma-chlordane were not present in the pulp in appreciable amounts. Approximately 50% of the total residue was contained in or on the skin of the tuber.