All the herbicides used for treatment in this study resulted in significant (P < 0.001) (Table 5) reductions in soil dehydrogenase activity when compared to the control. Soils treated with primeextra had the lowest set of soil dehydrogenase activities of 9.02, 12.55 and 16.09 µg (g-1min-1) after the second, fourth and sixth week of treatment, respectively (Figures 5, 6 and 7). Meanwhile, soils treated with glyphosate had the highest set of soil dehydrogenase activities after the second and sixth week of treatment (Figures 5 and 7) when compared to other herbicide treatments, while soils treated with atrazine had the highest dehydrogenase activity of 14.32 µg (g-1min-1) after the fourth week of treatment. In Figure 7, after the sixth week of treatment, glyphosate treated soils had the