HERBICIDE LEACHING IN COASTAL-PLAIN SOIL

The movement of atrazine, simazine, cyanazine, and metolachlor was stu died for two years under conventional tillage and no-tillage com. Grou nd water and soil samples were analyzed for the herbicides. Atrazine a nd simazine were detected in the ground water more frequently than met olachlor or cyanazine. In 1987, the herbicides were leached to the gro und water nine days after they were applied when 31.5 mm of rainfall o ccurred. At the 3.0 m depth atrazine concentrations ranged from 0 to 1 7 mug/L. There was no significant difference in herbicide movement bet ween conventional tillage and no tillage. The frequency of the herbici des detected in the ground water was directly related to the soil half -life of the herbicide. Concentrations of the herbicides detected in t he ground water were not related to the water solubility of the herbic ide. The research demonstrates pesticides may move to shallow ground w ater by macropore flow in the sandy soils of the Mid Atlantic states i f sufficient rainfall occurs shortly after they are applied.