Leaching sulfentrazone in North soils of Minas Gerais cultivated with sugar cane

Abstract

In view of the intense use of herbicides, coupled with the scarcity of information regarding the residual effect of these compounds in some Brazilian soils, the objective of this study was to evaluate the leaching potential by means of biological assays of the sulfentrazone herbicide in the 0- 20 and 20-40 cm of soils of the North of Minas Gerais cultivated with sugarcane. The experiment was conducted in the split - plot scheme, in a completely randomized design. The plots were composed of PVC columns, filled with soils of Salinas (MG) and Pirapora (MG), and the subplots, for 10 depths with intervals of 5 cm (0-5, 5-10, 10-15, 15- 20, 20-25, 25-30, 30-35, 35-40, 40-45 and 45-50 cm). At the top of the columns the dose of 600 g a.i. ha-1 of sulfentrazone was applied and 12 hours later, 60 mm of rainfall was simulated. After 72 hours, the columns were placed horizontally and opened longitudinally, divided into subsections of 5.0 cm. The evaluation of intoxication of the test plants was performed visually at 21 days after sowing, after which the aerial part of the bioindicator plants was cut. Symptoms of sulfentrazone intoxication were observed in the bioindicator plants up to 10 cm deep in the superficial layer (0-20 cm) and up to 15 cm in the deepest layer (20-40 cm) of both soils. In the two soil layers the sulfentrazone was detected in a higher concentration in the first five centimeters. Greater mobility of the herbicide was verified in the deeper layer of the soil (20-40 cm) indicating a greater leaching potential of the herbicide under these conditions.