MOBILITY AND DISSIPATION OF C-14-LABELED ATRAZINE, METOLACHLOR, AND PRIMISULFURON IN UNDISTURBED FIELD LYSIMETERS OF A COASTAL-PLAIN SOIL

Mobility and dissipation of C-14-labeled atrazine, metolachlor, and pr imisulfuron were evaluated for 1 year when applied preemergence to fal low loamy sand soil column field lysimeters. The relative mobility of the herbicides and/or metabolites in field lysimeters over the 1 year period in descending order was metolachlor > atrazine = primisulfuron. Thirty days after treatment, losses of C-14 due to apparent volatiliz ation, with other loss mechanisms being involved, accounted for 57, 43 , and 62% of the applied C-14 for atrazine, metolachlor, and primisulf uron, respectively. Chemical analysis of the 0-8 cm layer showed the p resence of four metabolites for atrazine, two for metolachlor, and two for primisulfuron. Calculated half-lives were 4 days for atrazine, 7 days for metolachlor, and 5 days for primisulfuron.