An assessment of the effects of herbicides on the population density of earthworms (Lumbricus terrestris) in soil

Abstract

Continuous burrowing, ingesting, turning, mixing, aeration and the improvement of the drainage of soil are the major roles played by earthworms in renewing soil fertility. Larger amounts of herbicides are applied to the soil continuously by farmers as they realize the importance of these herbicides. These herbicides could then accumulate to toxic levels in the soil and become lethal to microorganisms, plant, wild life and man. In this study, we sought to assess the effects of formulated products of glyphosate, atrazine and 2, 4-dichlorophenoxyacetic acid (2, 4-D) on the survival and reproduction of the tropical earthworm (Lumbricus terrestris). The highest number of deaths of adult worms was recorded for 2, 4-D formulation at 0.5 mg/kg and the lowest in glyphosate formulation at 0.2 mg/kg. The general trend was that, the number of cocoons reduced with increasing concentration across all the formulations of the herbicides.