Degradation of the Herbicide Halosulfuron-methyl in Two Soils under Different Environmental Conditions: Studies on the Fate and Behavior of the Herbicide Halosulfuron-methyl in the Soils (Part 1)

A laboratory experiment was conducted to study the degradation of the herbicide halosulfuron-methyl (NC-319) in Anjo (kaoline) and Nagano (montmorillonite) soils in the controlled environment of soil moisture, pH and temperature regime. In one experiment, four levels of moisture contents (10 to 200% of maximum water holding capacity (MWHC)) and four temperature levels (4 to 30°C) were applied. In the other experiment, pH of the two soils were adjusted to ca. 5-9, being maintained at 50% MWHC and 25°C. The dissipation followed first-order kinetics in all cases. In the two soils, halosulfuron-methyl was dissipated faster with increasing the temperature and lowering the soil pH. However, increasing moisture contents increased the dissipation rate of halosulfuron-methyl in Anjo soil but not in Nagano soil.