Published Paper Details:

Abstract Freshwater and the surface of soil provide the sites for aerobic phototrophic nitrogen (N2) fixation by free-living cyanobacteria and the Azolla-Anabaena symbiotic N2-fixing complex. Free-living cyanobacteria, the majority of which are heterocystous and nitrogen fixing, contribute an average of 20-30 kg N2, ha-1, whereas the value is up to 600 kg ha-1 for the Azolla-Anabaena system (the most beneficial cyanobacterial symbiosis from an agronomic point of view). Synthesis and excretion of organic/growth-promoting substances by the cyanobacteria are also on record. Recent results indicate a strong potential for cyanobacterial biofertilizer technology in rice-growing countries, which opens up a vast area of more concerted basic, applied, and extension work in the future to make these self-renewable natural nitrogen resources even more promising at the field level in order to help reduce the requirement for inorganic N2 to the bare minimum, if not to zero.