Adsorption, desorption and mobility of four commonly used pesticides in Malaysian agricultural soils

Working with Malaysian agricultural soils, high Freundlich adsorption distribution coefficients (K-ads(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 degrees C/30 degrees 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.