Leaching of Herbicides Commonly Applied to Sugarcane in Five Agricultural Soils

ABSTRACT: Leaching intensity depends on the physicochemical properties of soils and herbicides. Consequently, a good understanding of this process is essential to determine mitigation measures to reduce or eliminate the risk of water contamination around areas with sugarcane crops. Therefore, the objective of this study was to analyze the leaching of ametryn, diuron, hexazinone, and metribuzin by using columns in five soils with different physicochemical properties cultivated with sugarcane. The radiolabeled herbicides with 14C were evaluated at six soil depths (0-0.05, 0.05-0.10, 0.10-0.15, 0.15-0.20, 0.20-0.25, and 0.25-0.30 m) and in the leachate after 200 mm rainfall simulation for 48 h. Herbicide leaching was mostly affected by soil type. Ametryn and diuron were reported in the highest amount (>87%) on the topsoil (0-0.05 m), which was indicative of the low leaching of these two herbicides in the soil profile. Thus, these herbicides can contaminate surface water by runoff. Leachate percentage was always <0.3% for ametryn, diuron, and metribuzin; this was also the case for hexazinone in two out of the five soils. Hexazinone proved to be a potential contaminant of groundwater and metribuzin presented high leaching in the soil profile. Previous knowledge of the physico-chemical properties of soils cultivated with sugarcane is essential to recommend the use of these herbicides in weed management.