Sulfentrazone sorption, desorption, and mineralization in soils from two tillage systems

Publisher Website
Google Scholar
Abstract
Sulfentrazone sorption kinetics, desorption, and mineralization were evaluated in surface 7.5 cm of soils collected from long-term conventional-till (CT) and no-till (NT) plots. The soils used were Miami silt loam and Drummer silty clay loam from Illinois and Dundee silt loam from Mississippi. Sulfentrazone sorption kinetics in Dundee silt loam CT and NT soils were adequately described by a simple two-site equilibrium/kinetic model. Rapid initial sorption (within 1 h) was followed by a slower sorption and equilibrium, largely achieved by 72 h of shaking, with a negligible increase in sorption thereafter. The sorption Kf ranged from 1.02 to 3.44 among the six CT and NT soils. The Kf values were greater for NT compared to their respective CT soils. Overall, Kf values were higher in Drummer silty clay loam followed by Dundee silt loam and Miami silt loam soil. The N values were less than unity in all soils indicating nonlinear sorption. Sulfentrazone desorption was hysteretic with a very low rate of desorption. The total amount desorbed in four desorptions ranged from 58 to 72% of that sorbed. Less than 2.1% of applied 14C-sulfentrazone was mineralized to 14CO2 in Dundee silt loam CT and NT soils during a 77–d incubation. Relatively low mineralization of sulfentrazone suggests poor adaptability of native microbial populations that have not been exposed to this herbicide. Higher sorption and lower desorption of sulfentrazone in NT soils compared to CT soils suggest that NT systems (which tend to increase plant residues) may prolong sulfentrazone residence time in soil.