Influence of variation in physicochemical properties of pesticides on their adsorption isotherms and leaching behavior in egyptian clay soil.

The physicochemical properties of pesticides specifically solubility, volatility, and molecular structure are the primary factors determining their mobility. These factors govern their movement within the plant and their transport through the soil. The present work evaluated how variation in physicochemical properties influences the adsorption and leaching behavior of nine commonly used pesticides in tomato fields. The study includes a representative selection of major insecticides, fungicides, and herbicides to provide a comprehensive overview of their behavior in the soil. The adsorption capacity of the bulk soil was evaluated using the batch equilibration technique following two models. According to the Freundlich model, tebuconazole and difenoconazole were exhibited the highest adsorption affinity. On the contrary, the Langmuir model identified pendimethalin as having the strongest binding affinity to the soil followed by indoxacarb. Regarding the leaching experiments conducted in packed Egyptian soil columns, metalaxyl demonstrated the highest mobility, with 15% of the applied amount recovered in the leachate followed by acetamiprid. In contrast, the remaining pesticides exhibited low mobility, with the highest concentrations retained in the upper soil profile. These findings are step forward to develop management practices that mitigate the risks of pesticides, ensuring the protection of agricultural water quality and prevent groundwater contamination.