Diffusion of Atrazine, Propachlor, and Diazinon in a Silt Loam Soil

Abstract

The effect of soil temperature, soil moisture content, and soil bulk density on the diffusion of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine], propachlor (2-chloro-N-isopropylacetanilide), and diazinon [O,O-diethylO-(2-isopropyl-6-methyl-4-pyrimidinyl) phosphorothioate] in Ida silt loam soil was studied in the laboratory. Diffusion coefficients of 1.90, 1.36, and 0.63 mm²/day at 27 C for propachlor, atrazine, and diazinon, respectively, show in a relative way the expected movement of these chemicals in Ida silt loam soil. The greatest amount of movement occurred with high temperatures and high moisture contents. Soil moisture had more effect on atrazine movement than on propachlor movement, and very little effect on diazinon movement. Movement for all chemicals decreased with an increase in bulk density.