ADSORPTION OF ETHOFUMESATE BY AGRICULTURAL AND NATURAL SOILS

A study has been made of the effect of properties and composition of s oils on the adsorption of ethofumesate. Adsorption isotherms of ethofu mesate by agricultural and natural soils and by montmorillonite and hu mic acid were obtained. The correlations between the Freundlich K cons tants, and Kd distribution coefficients and the soil parameters were d etermined. Significant correlations (P<0.05) were found between K and clay content and between Kd and smectite content for the agricultural soils but the correlation with organic matter content was of borderlin e or no significance. Considering the agricultural and natural soils t ogether or the soils with an organic matter content >2%, a highly sign ificant correlation was found between K and the organic matter content . According to the r(2) determination coefficient, the organic matter content accounts for 88.4% of the variability in adsorption in the fir st case, and 92.2% in the second case. The log(10) Kd(om) values of so ils with an organic matter content >2% were similar and confirm the im portance of the organic matter as a determinant parameter in the adsor ption of ethofumesate by these soils. The adsorption of the herbicide by montmorillonite and humic acid confirmed the results obtained with the soils and point to the importance of the exchangeable cation natur e of the samples and of the temperature in the adsorption process.