Phytases belong to the class of phosphohydrolases that begin the step-wise hydrolysis of phosphates from phytates. Phytates are a derivative of myo-inositol, which is the primary storage form of organic phosphorus in plant cells. Phytase has been used globally to diminish phosphorus pollution and to enhance nutrition in monogastrics. In this review, the classification, sources, and diversity of microbial phytases, and their practical applications, as well as supplementation of the soil with transgenic and wild types of microbial strains, which can release phytase to enhance phosphorus availability for plant uptake and reduce the need for fertilizers, are discussed. The overexpressed microbial phytases in transgenic plants enhance the growth capacity of co-cultivated plants and can therefore be employed in agricultural and biotechnological practices, such as intercropping. The introduction of phytases into the soil for improved plant growth and enhanced crop yield can be accomplished without extra cost. A diverse group of photoautotrophic microalgae can synthesize phytase and will likely be useful in many human food and animal industries.