Increase sorption endosulfan by soil amendments and its effects on retention and leaching from soil.

Sorption of pesticides to substrates used in biopurification systems is an important control on the system’s efficiency. Ideally, pesticide sorption should occur fast so that leaching of the pesticide in the biopurification system is minimized. This study investigated the sorption and leaching of endosulfan on substrates commonly used in a biopurification system, i.e. manure, sugar cane compost and clay loam soil. The distribution of endosulfan along the soil profile, obtained from soil column experiments, indicated that the amount endosulfan retained ranged from 68.4% for the column filled with the original soil to 92.4% for that filled with the organic amended soil. Amounts of endosulfan recovered in the leachates, which ranged from 7.7% (organic amended soil) to 23.7% (unammended soil) of that applied, depended upon the loading rate and the source of organic amendment. Organic amendments significantly reduced the leaching of endosulfan and compost amended soil showed a higher potential than manure. It can be concluded that organic amendment may be an effective management practice for controlling pesticide movement. In fact, organic matter with strongly adsorbing sites can prevent endosulfan movement.