Herbicide Leaching in Coastal Plain Soil

Abstract

The movement of atrazine, simazine, cyanazine, and metolachlor was studied for two years under conventional tillage and no‐tillage corn. Ground water and soil samples were analyzed for the herbicides. Atrazine and simazine were detected in the ground water more frequently than metolachlor or cyanazine. In 1987, the herbicides were leached to the ground water nine days after they were applied when 31.5 mm of rainfall occurred. At the 3.0 m depth atrazine concentrations ranged from 0 to 17 μg/L. There was no significant difference in herbicide movement between conventional tillage and no tillage. The frequency of the herbicides detected in the ground water was directly related to the soil half‐life of the herbicide. Concentrations of the herbicides detected in the ground water were not related to the water solubility of the herbicide. The research demonstrates pesticides may move to shallow ground water by macropore flow in the sandy soils of the Mid Atlantic states if sufficient rainfall occurs shortly after they are applied.