Role of pH on Metribuzin Dissipation in Field Soils

Abstract

Metribuzin [4-amino-6- tert -butyl-3-(methylthio)- as -triazine-5(4 H )one] residue analysis of soil samples showed greater amounts of residue extractable at soil pH 6.7 than 4.6. Metribuzin leaching increased with increasing soil pH. Metribuzin disappearance from soil followed pseudo first-order kinetics. The half-life of metribuzin decreased as soil pH increased and increased at all soil pH levels as depth of sampling increased. The decreased activity and decreased rate of metribuzin dissipation at lower soil pH is apparently due to protonation and increased adsorption.