ADSORPTION OF PROMETRYN AND METOLACHLOR BY SELECTED SOIL ORGANIC MATTER FRACTIONS

Abstract
We studied the adsorption of prometryn and metolachlor by different fractions of soil organic matter, including humic substances (humic and fulvic acids), humin, and nonoxidizable soil organic matter. As a measure for adsorption evaluation, we used a distribution coefficient (Kdfom), calculated per unit of organic matter in each fraction. Humic substances showed high affinity for both herbicides. Humin fractions adsorbed significant amounts of prometryn, but not metolachlor. Hydrophobic bonding is suggested as a possible explanation.