Adsorption, Desorption and Mobility of Four Commonly Used Pesticides in Malaysian Agricultural Soils

Working with Malaysian agricultural soils, high Freundlich adsorption distribution coefficients (Kads(f)) were observed for paraquat (28·7 and 1419) and glyphosate (83·8 and 417) and lower values for 2,4-D (0·57 and 5·26) and lindane (2·65 and 14·1) in a sandy loam and a muck soil, respectively. Desorption of 2,4-D and lindane from the muck soil occurred. The adsorption of the pesticides was not affected by temperature (20°C/30°C), pH or addition of the pesticides as a mixture. Leaching of 2,4-D and lindane was evident under a high water influx (200 mm). Comparable results in the leaching of 2,4-D were observed between laboratory studies and a VARLEACH model prediction.