AbstractA survey has been made of some of the physical, chemical and biological interactions that influence the persistence and availability of herbicides applied to the soil. The most important physical interaction between herbicides and soil is considered to be sorption of the pesticide to the soil surface. This influences not only the rate of leaching of the herbicide through the soil and its movement in the vapour phase, but also the rate of chemical and microbial decomposition. An attempt has been made to construct a model for the persistence of some hydrolytically sensitive herbicides to enable their persistence in soils to be deduced from hydrolysis rate‐constants and adsorption data.The formulation used and the method of application of the herbicide to the soil can also have an important influence on its persistence.