Question

Describe the various processes and reactions affecting pesticides which enter the soil.

Answer 1

Certain percentage of pesticides percolates into the soil, through its pores. Depending on the solubility of the pesticide, it reaches the ground water. But sorption process can retain the chemicals from getting transported with leaching water. Most of the pesticides used are organic chemicals which can be degraded to inorganic end products by chemical, photochemical and biochemical means.Some amount of pesticides is removed from surface layer due to runoff from soil and by plant uptake.

Fate of pesticide is affected by interrelated factors such as solubility, surface adsorption volatility, ultraviolet irradiation, hydrolysis, chemical rearrangement etc. Combined weathering action of wind, rain, temperature, humidity also affect its breakdown. This breakdown is followed by microbiological action.