[Sorption and desorption behavior of the herbicide mefenacet on soils]

The sorption-desorption experiments of the herbicide mefenacet on five soils with different physicochemical properties were conducted using bath equilibrium methods, and the effects of soil organic matter and pH value on sorption of this herbicide were also investigated. The results showed that the sorption and desorption behaviors of mefenacet on soils could be well described by both the linear model and Freundlich model. Sorption distribution coefficients K(oc) for five tested soil are between 849.5 L x kg(-1) and 1 818.8 L x kg(-1), which shows that mefenacet can be well adsorbed on soils. It is found that the sorption coefficients, K(d), K(f), and K(f) (1/n) had good correlation with organic matter content (OM) in soils. It is obviously suggested that organic matter was the dominant factor affecting the sorption of mefenacet on soils. For the same soil, the sorption amount of mefenacet decreased with the increase of pH value. The desorption hysteresis of mefenacet was revealed in the single-cycle sorption and desorption experiments, which indicated a weak transferability of this herbicide in soils.