Adsorption and degradation behavior of six herbicides in different agricultural soils

摘要

This study focuses on the assessment of herbicide adsorption and degradation in three soils (Haplic Chernozem, Haplic Fluvisol, and Arenic Regozem) from different agricultural regions of the Czech Republic where sunflower is cultivated. Soil samples were used in laboratory batch adsorption and degradation experiments for six herbicides commonly used on sunflower crops. The findings are used to examine the effect of soil and herbicide properties on adsorption and degradation, as well as to determine the possible relationship between the two processes. The (K-f) sorption coefficient ranged from 1.07 to 135.37 cm(3/n)mu g(1-1/n)g(-1), and sorption increased in the following order: dimethenamid-p pethoxamid S-metolachlor flurochloridone aclonifen pendimethalin. Adsorption of all six herbicides was positively correlated with soil organic matter content (p 0.001), and cation exchange capacity (p 0.001). pH was negatively correlated with the adsorption of all six compounds (p 0.001). Degradation rates of herbicides ranged from 0. 012 to 0. 048 day(-1), which corresponding to the half-lives (DT50) between 14 and 57 days, respectively. The highest half-life values were found in Haplic Fluvisol (a loam with higher organic matter content and lower pH). Results showed that both adsorption and degradation of herbicides are mainly controlled by soil organic matter. A negative relationship was found between the sorption coefficient and the rate of degradation. It can be concluded that the Freundlich sorption coefficient (K-f) can be a good predictor for the degradation of the studied herbicides.