Effect of herbicides on soil microorganisms

Contrasting reports are available in regard to effect of herbicide on soil microflora. Microorganisms are able to degrade some herbicides and utilize them as a source of biogenic elements but other group of herbicides may affect microbes adversely. In our study microbial activity including bacteria, fungi, Azotobacter as well as phosphate solubilizing fungal population was highest when no herbicide was applied. In rhizospheric soil, the negative effect of herbicides was noticed on Azotobacter population but there was no adverse effect in terms of total bacterial count. Sulfosulfuron did not show any toxic effect to the phosphate solubilizing fungus studied. Clodinofop exhibited maximum toxicity to phosphate solubilizing fungus under in vitro conditions.