Application of Biofertilizers Containing Free-living Nitrogen Fixer Micro Organisms in Agriculture

Atmospheric nitrogen fixation as an exclusive phenomenon is accomplished by nitrogenase enzyme of prokaryotic microorganisms namely diazotrophs including bacteria, actinomycets and cyanobacteria. Nitrogen fixation is accomplished as form of symbiotic, associative and free-living systems. In free-living systems nitrogen is fixed without the help of plants. Azotobacter, the first diazotroph was discovered over a century ago and application of it was started in agriculture about half a century ago. Nowadays, in some countries a large amount of diazotrophs are used as inoculums. In recent years, some companies produce diazotroph inoculums in Iran. Some kinds of organic and inorganic such as torb, perlite, and charcoal, bran and cane molasses are suitable for diazotroph inoculums careers. The population of inoculums is reported as number of microorganisms per milliliter or gram of inoculums and recommended for a certain amount of seeds or in hectare. The diazotroph inoculums’ are used in form of soil or seed and seedless application or in rhizosphere of trees.