Adsorption and Mobility of Metolachlor in a Sandy Loam Soil

Metolachlor adsorption ranged from 7.2 to 24.8% (av.14.2%) for an alluvial soil and 31.5 to 64.2% for FYM. Sshaped isotherms signified that the soil had a higher affinity for water than the herbicide, adsorption was in vertical configuration and bonding was monofunctional. Metolachlor sorption was correlated with organic matter content of the substrates by computing Koc values. It was found higher in FYM (727.5) containing 6% organic matter and was quite low in alluvial soil (31.4) containing only 0.41% of organic matter. Metolachlor was found to move down the soil depth of 5–10 cm within 4 hrs of its application in the field. Rainfall (169.3 rom) closely following its application played a major role in the leaching beyond 75 cm soil depth within 21 days.