Bioassay, Leaching, Pendimethalin, PVC columns

A laboratory column experiment was conducted to study the leaching behaviour of pendimethalin in sandy clay soil of Madhya Pradesh. Soil sample (0-15cm) was packed in PVC columns and conditioned by adding water one day before the herbicide application. Pendimethalin was added directly to column after dilution with 10 ml water at recommended dose (1.0 kg/ha) and double the recommended dose (2.0 kg/ha). Water was added every day to encourage movement of herbicide. After seven days, the column was split vertically into two halves. The herbicide activity was determined at different depths through bioassay by using maize as sensitive plant. The growth of maize due to pendimethalin was affected in the upper layer of soil up to 5 cm at recommended dose (1.0 kg/ha) and up to 10 cm  at double the recommended dose. This reveals that pendimethalin does not leach below 10 cm in soil even at double the recommended dose.