Sorption and desorption of mesotrione alone and mixed with S-metolachlor plus terbuthylazine in Brazilian soils

The mixture of herbicides is a widely used technique in weed control in several crops, including maize. However, interactions that might potentially result from mixing herbicides are a matter of constant concern and research. Soil capacity to retain herbicides directly influences the final destination of these molecules in the environment. The aim of this study was to evaluate sorption and desorption of mesotrione applied alone and mixed with S-metolachlor + terbuthylazine in samples from seven Brazilian sites cultivated with maize. Mesotrione sorption (alone and mixed) was evaluated five concentrations with 0.125, 1.042 and 0.625 mg kg(-1) corresponding to the field dose of mesotrione, S-metolachlor and terbuthylazine, respectively. Sorption of mesotrione applied alone and mixed had K-d (sorption coefficient) values ranging from 0.08 to 5.05 kg L-1 and from 0.09 to 520 kg L-1, respectively, with similar behavior across soils. Mesotrione sorption was influenced primarily by the clay mineral (CM) content and the soil pH. The mode of application (alone or mixed) did not influence sorption or desorption. Mesotrione sorption was relatively low in soils, which creates the potential for leaching in maize producing areas. (C) 2016 Elsevier B.V. All rights reserved.