Effect of Atrazine, 2,4-D Amine, Glyphosate and Paraquat Herbicides on Soil Microbial Population

Herbicides’ toxic impact on the non-target soil microorganisms which play roles in degrading organic matter, nitrogen and nutrient recycling decomposition needs to be considered. In present study, effect of four (4) most commonly used herbicides, viz; atrazine, 2, 4- D amine, glyphosate paraquat was assessed over a period fifteen continuous days (exposure period). The herbicide treatments were normal recommended field rate, (6.67 mg active ingredient per gram for 6.17 4-D 5.56 glyphosate, 2.46 paraquat), half double rates. Tables 4.1 through 4.5 showed various heterotrophic bacterial colony counts obtained from treatments, ranging control (Day 1; no applied) 3, 6, 9 15 after application respectively. Two general trends are readily observed: first is that, upon herbicide, microbial growth steadily diminishes, up 6th day. However, there it continues increase till end experiments (day 15). This applies each herbicide. Firstly, addition herbicides evaluated using two samples, two-tailed Z-Test means, at 95% confidence interval, results that difference before 0) immediately 3), statistically significant (Z = 3.32, Z critical 1.96, P 0.00090). indicates affects population.