Transformation of Herbicides in the Environment

Abstract

The share of herbicides in Indian agriculture is increasing at a fast rate. Presently, it is well around 30% among all other pesticide groups. Farmers are becoming more inclined towards herbicide application than manual weed management due labour acute shortage. But over-dependence on herbicides may lead to some environmental crisis in the future, if it is not taken care of timely. To avoid hazards due to herbicide application, we should know the fate and behaviour of every herbicide so that proper mitigation methods can be developed. In this article, degradation patterns of some herbicides under various conditions have been discussed.

Herbicides, after being applied to the target organisms, are transported into different compartments, viz. water - ground or surface, soil system, tissues of plants and animals, and atmosphere. The rate and type of transportation depends on many physico-chemical factors of the herbicides and the environment. After being compartmentalized, herbicide molecules are to struggle with many reactive species like super oxide, peroxide, and singlet oxygen; or with enzymes of microbes, plants and animals. These abiotic and biotic forces chemically transform, or degrade the herbicide into several compounds. The degree of degradation of any herbicide depends on the factors helping in the generation of reactive species or enzymes in the environmental compartments. Those factors like soil clay, inorganics, humic substances and microbes are important aspects to be considered for finding out mitigation processes.