Effect of Organic Matter on Adsorption of Imidacloprid on Soil

The effect of organic matter (OM) on the adsorption of imidacloprid has been investigated by studying the adsorption in soils containing OM (normal) and without OM (hydrogen peroxide treated). Adsorption was carried out using batch equilibration technique. Sorption of imidacloprid on untreated and H₂O₂ treated soil followed Freundlich equation. The K_f values for imidacloprid in hydrogen peroxide treated soils were less than in corresponding untreated soil. The K_f value of imidacloprid was the highest for alfisol soil followed by ultisol, inceptisol, vertisol and oxisol in both untreated and H₂O₂ treated soils correlating to the OM content of these soils. Sorption coefficient 1/n, however, increased after H₂O₂ treatment of soil, implying stronger binding of imidacloprid to the inorganic fraction of soil.