Herbicide, Movement, Pendimethalin, Soil conditions

Movement studies were carried out using packed soil columns to know the distribution pattern of pendimethalin in clay loam and sandy loam under saturated and unsaturated conditions. Pendimethalin was applied at 20 mg/kg of soil and the soil columns were kept for movement studies at time intervals of 1, 3, 5, 7, 15, 22 and 37 days. The soils used in the study were clay loam and sandy loam. Pendimethalin remained primarily in the top soil layers. Under saturated conditions movement of pendimethalin was more in sandy loam as compared to clay loam. Under unsaturated conditions, pendimethalin showed more mobility in clay loam.  The increase in herbicide movement was observed with increase in days. The factors that influence movement are the herbicide solubility, soil structure and texture and the amount of water passing through the soil profile influenced movement of herbicide. Pendimethalin moved up to 20-25 and 5-20 cm under unsaturated and saturated conditions at 37 days after application, respectively.  In clay loam soil, under saturated and unsaturated conditions, pendimethalin moved up to 15-20 cm  at 37 days after application.