ABSTRACT
Persistence in soils is an important feature of a herbicide as it determines its suitability or otherwise in a particular soil and cropping situation. Herbicides that decompose too readily are less desirable in some situations as they cannot be very effective on the weeds emerging later. In other situations, herbicides that have longer persistence of activity are unsuitable as their toxic residues can injure the sensitive crops g rown in rotation. Thus, a herbicide which becomes more desirable in some situations may not be useful in other situations. Knowledge of the persistence and residual effects of herbicides is essential to use them safely and effectively and to programme nonhazardous chemical weed management schedules. Besides, it also helps in ascertaining their long-term effects on the soil environment, which includes soil microorganisms, soil fertility, etc.
