*Contribution from the Division of Agricultural Chemicals, Indian Agricultural Research Institute New Delhi 110 012.
The hydrolysis of isoproturon [N-(4-iiopropyl phenyl - N’,N’ - dimethyl urea] in aqueous medium followed first order kinetics with respect to the herbicide concentration. The half-life of isoproturon decreased with an increase in pH. Depending upon pH, 54 to 70% hydrolysis of the herbicide was recorded in 10 weeks. The half-life of isoproturon in soil, calculated from first order plots, varied between 12.5 to 15 days and it persisted in soil upto wheat (Triticum aestivam L.) harvest (10 weeks after application) though in small quantities (6 to 9%). Wheat plants and grains were free of isoproturon residues at the time of harvest even when used as post-emergent.
