Humus pesticide interaction: The fate of pesticide in soil environment: An overview

Abstract

Due to its requirement in controlling crop pests the use of pesticides is unavoidable in modern agriculture. Contaminations of water and soil resources due to pesticides could be avoided by understanding the fate of pesticides which in other hand will be useful for their safe use as they may cause fatigue if misused. The fate of pesticides in soils are dependent on their sorption, decomposition and movement in the soil system. Sorption of a pesticide in soil system controls its degradation and leaching within it which occurs mainly due to various biological and chemical interaction between pesticide and soil organic matter. Soil organic matter and clay content are the deciding factors for sorption of pesticides in the soil system. Pesticides are bound to humic substances of soil organic matter by a number of mechanisms i.e. ionic bonding, charge transfer, Vander Waals forces, ligand exchange and hydrophobic adsorption and partitioning which are responsible for its movement and interaction within the soil system. Addition of organic constituents to soil is a worldwide practice which in turn affects the dynamics of applied pesticides to soil every year which varies from soil to soil. Organic amendments have been reported to increase sorption of pesticides on soil surface. Conditions that favor microbial activity were found to enhance the rate of pesticide degradation and which inhibits microbial activity tends to reduce rate of pesticide degradation. Organic matter addition tends to modify leaching of pesticides. Studies have shown that organic matter amendments induces restriction of pesticide leaching in soil ultimately reduced concentration of pesticides in ground water.