To increase crop yields and soil fertility, organic fertilizers play an important role. This is because they not only enrich the soil with all the nutrients, but also improve its properties. The current state of use of organic fertilizers encourages the search for new types of local fertilizer resources. Phosphorus is directly involved in many processes of plant life, and ensuring a normal level of phosphorus nutrition — one of the main conditions for the formation of high crop yields. The soil microbiota is actively involved in the mobilization of sparingly soluble phosphates, which has a positive effect on plants, improving their phosphorus nutrition, growth, development and productivity. Therefore, phosphate-mobilizing microorganisms can become one of the components of bioorganic fertilizers. The dynamics of development of phosphate-mobilizing microorganisms in the composting of sewage sludge (ERU) of biological treatment plants (SBU) — «Northern» and «Southern» Odessa with fillers (winter wheat straw and sunflower seed husk) to increase biofertilizers with water fertilizers. Research methods: microbiological, statistical. Analysis of the dynamics of phosphate-mobilizing microorganisms during 3 months of research showed that at the beginning of composting there is a rapid development of microorganisms that dissolve organophosphates, and as the mineralization of organophosphates, the number of bacteria in this group decreases. After 60 days of composting, the development of bacteria is dissolved, which dissolve the mineral forms of phosphates. The gradual transformation of highly soluble phosphorus compounds into labile helps to reduce the number of microorganisms that dissolve both organic and mineral forms of phosphorus. The results of research indicate the possibility of obtaining bioorganic fertilizers with the participation of phosphate-mobilizing microorganisms.