Physical, chemical and biological processes involved in the degradation of pesticides

2 Physical, chemical and biological processes involved in the degradation of pesticides 

Depending on the exact location of the pesticide (on the surface or below the surface of the soil) different processes will predominate in the degradation. On the soil surface, at the boundary between the gaseous phase (air) and solid phase (soil) the physico-chemical phenomena such as photochemical decomposition and oxidation are of great importance. 

The soil moisture helps to speed the degradation of pesticides in two ways. On the one hand, it presents more favourable conditions for the activity of microorganisms and, on the other hand, it facilitates the transport of pesticides, increasing the rate of their evaporation. An exception are 

The presence of organic substances and clay particles increases pesticide persistence in the soil. This is a result of an increased adsorption of these substances on humus and clay particles. As a result of this, pesticides become a suitable substrate for the activity of soil microorganisms. The rate of their evaporation and washing out is decreased. 

Certain pesticides pass from the soil through the root system into plants and, as a result of this, their content in the soil is reduced in the vicinity of roots. 

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