Leaching of sulfentrazone in soils of reforestation in Brazil

Abstract

This study determined the mobility of sulfentrazone in soils used for reforestation (Haplic Planosol, Ultisol, Humic Cambisol, and Regolithic Neosol) in the south of Brazil. To form the soil columns, previously prepared PVC tubes (10-cm diameter and 50-cm long) were filled with soil samples. Sulfentrazone was applied on top of the columns, which contained soil with moisture close to the field capacity. Subsequently, simulated 60-mm rainfall was applied to the columns. After draining the water, the columns were opened, and soil samples of each segment of 5.0 cm of the columns were taken for analysis of sulfentrazone by high-performance liquid chromatography. The herbicide was extracted from the soils by the solid–liquid extraction method with low temperature partition (SLE-LTP), which was adapted and validated. Sulfentrazone showed high mobility in the four soils analyzed, but presented lower mobility in the Humic Cambisol due to its lower rate of desorption. In this soil, the herbicide remained in the upper layers of the column, while in the other soils the herbicide was distributed throughout the columns. The soil that held the highest concentration of the compound in the first two segments of the column (0–5 and 5–10 cm) was the one with the highest clay content. Thus, it was concluded that the sulfentrazone leaching process in the soils analyzed is dependent on the chemical and physical characteristics of the soils, particularly, the contents of clay, sand, and organic matter.