Persistence of Several Herbicides in a Soil Cropped to Sugarcane

Abstract

Experimental plots were treated with Ametryne, Diuron, Fluometuron, Norea and Prometryne at the rates of 4, 8, 16 and 32 pounds per acre. Terbacil was applied at the rates of 2,4,8 and 16 pounds per acre 13 months prior to soil sampling. Herbicide residues in soil samples collected from experimental plots were bioassayed using oats (Avena sativa L.) as the indicator plant. Residues present in the soil at the 0- to 4-inch depth were found to be relatively low in plots treated with 4 pounds per acre of Ametryne, Diuron, Fluometuron, Norea or Prometryne, or 2 pounds per acre of Terbacil. Residues were found to increase in the 0- to 4-inch depth as the rate of herbicide was increased. Fluometuron and Diuron were detected at rather high concentrations when applied at 16 and 32 pounds per acre. At the corresponding higher rates, only small to moderate amounts of Ametryne, Norea, Prometryne and Terbacil were detected. In general, Fluometuron, Diuron, Ametryne and Prometryne did not penetrate in appreciable amounts beyond the 0- to 4-inch depth regardless of the concentration. However, the greatest amount of Terbacil and Norea were found to accumulate in the 4- to 8-inch and 8- to 12-inch depths, respectively.