COMPETITIVE SORPTION OF ATRAZINE AND METOLACHLOR IN SOIL

Atrazine and metolachlor co-application to soil created competitive so rption between the two herbicides, producing smaller partitioning coef ficients than for separate atrazine and metolachlor applications. The partitioning coefficients for both compounds were also less when appli ed in a commercial formulation, compared with separate analytical-grad e applications. Since the Freundlich Slope of the isotherms was less t han unity (0.83 to 0.87), the sorption strength of the herbicides decr eased with increasing solution concentrations. Based on the Freundlich adsorption values obtained, this study concludes that atrazine and me tolachlor co-applications on agricultural fields have the potential to increase the mobility of these herbicides in soil, thereby also incre asing:the risk for groundwater contamination.