Leaching of sulfentrazone in Brazilian "Cerrado" soils by chromatographic and biological methods

Abstract

Sulfentrazone is a mobile herbicide in the soil that can reach groundwater. The objective of this study was to verify the leaching of sulfentrazone in samples from three Brazilian "Cerrado" soils, and compare the biological with the chromatographic method to determine the leaching. The soils were PVC columns (10 cm in diameter x 50 cm in length), 1.5 kg ha-1 of sulfentrazone was applied to the top of the columns. Twelve hours after the application of the herbicide, they were submitted to simulated rainfall (60 mm). To the herbicide leaching, in each column, soil samples were collected every 5 cm, being the experiment mounted in subdivided plots (plots: columns, subplots: depths). From these, a fraction was sent to the laboratory for analysis by high performance liquid chromatography (HPLC). Another fraction was placed in pots, performing bioassay with Sorghum bicolor. Sulfentrazone leached more in treatments Tillage System - Sandy Soil - High acidity and Tillage System - Red Latosol - Low acidity, being quantified by HPLC at depths of 5, 10 and 15 cm and detected in the same depths by bioassay. In treatment, Native Forest - Red Latosol - High acidity the herbicide leached up to 10 cm, also being detected by HPLC and bioassay. The biological method, when compared to the chromatographic, presents good sensitivity to sulfentrazone, being able to be used for leaching study of this herbicide.