Emurotu M. O. and Anyanwu C. U
The effect of two herbicides (atrazine and butachlor) on soil phosphatase and urease activities was assessed every fourteen days over a period of seventy (70) days. Soil samples from Kogi State University farm were treated with herbicides at company recommended rates, concentrations above and below the recommended rates. Pseudomonas spp., Bacillus spp. and Flavobacterium spp. were the most frequently isolated bacteria while Aspergillus niger, Aspergillus flavus, Penicillium spp., Trichoderma spp., Mucor spp. and Fusarium spp. were the most frequently isolated fungi. As herbicide concentrations increased, decrease in phosphatase activities was observed. Atrazinetreated soils had more acid phosphatase activities than butachlor-treated samples, while butachlor-treated samples had more alkaline phosphatase activities than atrazine. As concentrations of the herbicides were increased, the urease activities increased correspondingly, with butachlor-treated soils having more urease activities than atrazine-treated soils. From this study, butachlor is more microbial and environmental friendly than atrazine. Atrazine was shown to be more toxic to microflora and enzyme activity in the soil than butachlor.
