the place of phosphatic biofertilizers and necessity to develop them in iranian agriculture

carbonatic origin of most arable land in the country, caused to decrease phosphatic fertilizer use efficiency and because of this phenomenon, farmers annually add a large amount of these chemical compounds to their field to get proper results. international shortage and increasing prices create some problems for importing phosphorus fertilizers to the country. on the other hand using more and more of these compounds caused environmentally pollutions .by changing unavailable forms of soil concentrated phosphorus to the available forms, in parallel to lower need of phosphatic fertilizers, plant growth and yield also can be guaranteed .in rhizospheric soil some of microorganisms including bacteria and fungi have ability to change soil fixed phosphorus to soluble one by specific mechanisms. isolation, recognition, their production and formulation of these microorganisms constitute the main frame of production of a kind of biofertilizers which is named phosphatic biofertilizers. in developed countries, the new formulations of these biofertilizers contain different kinds of microorganisms for multiple purpose including supply plant mineral needs and help to their host to be more resistant against biotic and abiotic stresses. these kinds of biofertilizers including sulfur oxidizing, phosphate solubilizers and mycorrhizal fungi were used in the country from 10 years ago. research results showed that these microorganisms efficiencies are in relation to plant host and soil physical and chemical properties. in over all they can supply 25 to 50 percent of plant phosphorus demand. trying to use modern technologies to produce these microorganisms and their formulation caused to develop using them in the country and help us to decrease usage of phosphatic chemical fertilizers.