Adsorption of Ionisable Pesticides in Soils

Pesticides are intensively used in agriculture, and much effort is expended to manage and reduce possible deleterious effects on the environment.The soil compartment has a major influence on the fate and behaviour of pesticides applied to crops preemergence or early postemergence or chemicals subject to washoff from crop surfaces. Once in the soil, pesticide molecules partition between the aqueous and solid phases, which affects many other aspects of their behaviour: sorption can be rate limiting to volatilization, bioavailability (and thus efficacy and biodegradation rate), and subsurface transport. Understanding the fate of a pesticide in soil is fundamental to the accurate assessment of its environmental behaviour and vital in ensuring the safe use of new and existing products. It is also necessary to develop and validate computer simulation models for use as predictive tools in future environmental fate assessments.