Isoproturon Persistence in Field Soil and its Impact on Microbial Population under North-Western Himalayan Conditions

Persistence and dissipation behavior of isoproturon and its impact on soil micro flora under field conditions was studied during Rabi season in mid hill zone of Himaccal Pradesh in Innia. Isoproturon was applied as post emergence treatment to wheat crop at 1.5, 2.0 and 2.5 kg ha⁻¹ doses. Isoproturon residues in soil persisted up to 45, 60 and 60 days at three rates of applications, respectively. Dissipation followed first order kinetics with half life in the range of 12.1–21.0 days. Total miccobial population in soil significantly declined over control at all the three levels of applications. However, the inhibitory effect of isoproturon was seen upto 10 days only. At 60 days after herbicide application and at the harvest of the crop, the differences among different treatments were non significant and thereby indicattng that bacterial, fungal and actinomycetes population in isoproturon treated soil recovered from the initial setback in microbial population.