Role of Free Living Nitrogen Fixing Bacteria in Soil Nitrogen Economy—A Critical Review
Abstract
Free living nitrogen fixing bacteria have a potential role in tapping atmospheric nitrogen for gainful agriclture. Among these, Azotobacter and Clostridium are important. Azotobacter cullure inoculatton has been attempted in a limited way for its possible beneficial use. Preliminary reports, even from India, suggest that crops receiving such inoculation grow better than uninoculated ones. It has, however, not been established that this is because of augmentation of nitrogen supply in the soils. In fact, it has been suggested that better yield obtained is due to a better stand ensured by exudates from the bacteria. Azotobacter seems to be limited in its usefulness because of its high requirement of meta-bolizable energy for good nitrogen fixation. An attempt will be made to critically review the existing state of knowledge on this aspect, the prospect in the future and the genetic approaches one can employ for remedying the shortcomings that limit their use.
