Movement of Methazole and Its Degradation Products in Soils
1977
Swoboda, Allen R. | Merkle, Morris G.
The movement of 2-(3,4-dichlorophenyl)-4-methyl,1,2,4-oxadiazolidine-3,5-dione (methazole) tagged with ¹⁴C was studied in Lakeland sand, Nacogdoches sandy loam, Norwood clay loam, and Miller clay soils. The herbicide, at a rate equivalent to 3.4 kg/ha, was incubated for 30 days with each soil. The treated soil, equivalent to 2.5 cm in a 15-cm diameter column, was placed on the surface of untreated soil contained in columns. The columns were subsequently leached daily with 1.25 cm of distilled water for 42 days. Very little ¹⁴C-activity was detected in the leachate. The percentage of ¹⁴C-tagged material added which leached through the soils was 2.75, 0.84, 2.87, and 1.01 for the Lakeland, Nacogdoches, Norwood, and Miller soils, respectively. Upon sectioning the columns, the majority of ¹⁴C-active material was found in the 0- to 2.5- and 2.5- to 7.5-cm sections, although a considerable amount of material was found in the 7.5- to 15-cm sections of the Lakeland and Norwood soil columns. Very little herbicide was found below 15 cm in any of the soil columns. Essentially all of the ¹⁴C-active material present in the soils could be extracted by either shaking for 2 hours with methanol or refluxing with methanol for 16 hours in a soxhlet extractor. Wet combustion of soil samples indicated that very little ¹⁴C-activity remained in the samples extracted by the soxhlet method. Methazole was readily converted to 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU) and 1-(3,4-dichlorophenyl) urea (DCPU) in the soils studied, with DCPMU being present in the largest quantities. Very little unaltered methazole or unidentified degradation products were detected in the soils.
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