Nonbiological degradation of the herbicide metribuzin in Manitoba soils.

Abstract

Degradative loss of herbicides in soil can take place by chemical or biological means. HYZAK and ZIMDAHL (1972) bave suggested that non-biological degradation of metribuzin in soil may be the most important mode of breakdown following application to San Luis sandy loam. Later work by HYZAK and ZIMDAHL (1974) suggests that degradatlon of metribuzin in soil is an approximately first order phenomenon at 5 ~ 20 ~ and 35~ yielding a linear plot of log (residual metribuzin) vs time. Their results show no induction period following application of metribuzin. Several variables have been suggested to influence metribuzin persistence in Canadian prairie soils; e.g., temperature, organic matter content, and adsorption properties of soils. HYZAK and ZIMDAHL (1974) show that degradation of metribuzin in soil increases with temperature, and increased degradation in the field in Almasippi very fine sandy loam has been shown by WEBSTER and REIMER (1976a) to correspond to temperature increases in the soil. The latter two variables, however, are characteristics of specific soil types, and attention was turned in this study to an evaluation of the ~fluence of four Manitoba soils on non-biological degradation of metribuzin.