Environmental Fate of Herbicide Use in Central India

Abstract

In the present day agriculture, herbicide use is increasing due to escalating labour cost, easy availability of herbicides, rapid weed control in cropped and non-cropped situations. In India, the herbicide use has increased tremendously during the last 10 years. Since herbicides are synthetic chemicals, therefore excessive and frequent use may cause herbicide residue problems, toxicity to plants, residual effects on succeeding or intercrops crops, harmful effects on non-targeted organisms, and health hazards to human beings and animals. Many herbicides are detected as bound residues and make them unavailable to the targets and contaminating the ecosystem in a number of ways. Therefore, monitoring of herbicide residues in plants, fishes, soil, water, and other commodities is very important. Fate of herbicide in soil depends on several processes such as absorption, volatilization, adsorption, leaching, runoff, photodecomposition, dissipation by microbial and chemical processes. Therefore, studies were conducted to determine persistence and herbicides residues in soil, water and crops including cereals, vegetables, pulses and fodders. Half-lives of herbicides were found to be 57–71 days for imidazoline, 13–60 days for phenylureas, 13–147 days for sulfonylureas, 12–58 days for triazines, 5–60 days for chloroacetinalides, 12–77 days for dinitroanilines, 19–29 days for diethyl-ethers, 19–24 days for thiocarbamates and 8–24 days for fop group of herbicides in the soil. Herbicide residues in about 80% samples were found below the detection limit (BDL). However, residues in 13.4% samples were found below the maximum residue limit (MRL), and 6.6% samples were detected above MRL values. At harvest, herbicides in various commodities were found either below MRL or BDL. Herbicide contamination of plants and natural waters was found to be infrequent and at low levels in the soils of central India.