Multiple Action of Azotobacter

Azotobacter is a free living nitrogen-fixing bacterium. It combines about 9 to 13 mg of atmospheric nitrogen per g. of sugar oxidised. The conservative estimates of nitrogen added to the soil show that it only fixes 10.25 Kg N/ha. There is controversy regarding its use as a bacterial fertilizer as there were inconsistent results. Inspite of initial setback, many interesting results were reported during seventies. Our results show that Azotobacter inhibits she growth of pathogenic fungi Fusarium moniliforme Alternaria alternata, Curvularia sp., Macrophomina phaseoli, Fusarium solani and others and different strains so Azotobacter vary in their effect. In case of wheat crop, ear emergence was earlier by a week due to bacterization of the seeds with Azotobacter. Azotobacter chroo-coccum was also found to solubilize tricalcium phosphate; solubility ranged from 8 to 16% as against the 12 to 19% solubility by Bacillus megatherium var. phosphaticum. Azotobacter also effectively helps in improving the germination of seeds of different crop plants. Our results on strain variation reveal the need of selection of strains for different crops and agro-climatic conditions.