Abstract. Background. At present, on the soils where the agricultural crops of the Republic are grown, phosphorus and potash fertilizers are used much less than necessary, organomineral fertilizers containing humic substances are practically not used. Especially, the non-use of humus-containing fertilizers leads to a gradual loss of soil fertility, and its restoration is an extremely complex, long and laborious process, at the same time, the Kyzylkum phosphorite complex contains a huge amount of phosphorite waste with a content of 10-15% P2O5, as well as phosphorite flour containing 17-18% P2O5. Their processing into high-quality complex organomineral fertilizers using waste from livestock farms and their use in agriculture is relevant. Purpose. Study of the process of obtaining complex organomineral fertilizers containing humic substances, nitrogen, phosphorus, potassium and other macro- and microelements in a balanced ratio based on cattle manure, phosphate rock (PR) of the Central Kyzylkum (CK) with the addition of various mineral fertilizers by composting. Methodology. Preparation of composts by mixing cattle manure with PR and with the addition of various mineral fertilizers, studying the composition of the resulting fertilizers using known methods, depending on the mass ratio and exposure time. Originality. For the first time, the degree of humification of organic substances in cattle manure, the transition of P2O5 into an assimilable form for plants, the release of organic substances and nitrogencontaining compounds into the gas phase during composting of manure with PR and the addition of various mineral fertilizers were studied. The optimal conditions for obtaining complex organomineral fertilizers containing humic substances, nitrogen, phosphorus, potassium and other macro- and microelements in a balanced ratio have been determined. Findings. Compost was prepared on the basis of manure, phosphate rock of the Central Kyzylkum desert and the addition of various mineral fertilizers at mass ratios of manure: PR: mineral fertilizers = 100: 10: (0.5-4). The kinetics and degree of transformation of the organic part of manure into humic substances and indigestible forms of phosphorus into a form assimilable for plants in phosphorite flour have been determined. Losses of organic matter and nitrogen in composts have been determined. It is shown that with an increase in the duration of composting, the formation of humic substances and mobile forms of phosphorus increases, with an increase in the amount of mineral fertilizers in composts, the loss of organic matter and nitrogen decreases, and the degree of conversion of the organic part of manure into humic substances increases. The use of PR, urea and potassium chloride as an additive to composts with a ratio of manure: PR: additive = 100: 10: 4: 2 after the compost has been kept for 90 days in finished fertilizers, the content of the general form of P2O5 decreases from 2.15 to 1.94, and the content nitrogen and potassium increases from 0.3 to 1.85 and from 0.56 to 1.73%, respectively. In addition, with an increase in the holding time of complex mixtures, regardless of the type of additive used in this work, the relative content of the assimilable form of phosphorus in them increases. So, with the addition of 4% ammonium sulfate and 2% potassium chloride after 90-day composting, the content of P2O5usv. increases from the initial - 16.57 (PR) to 69.75%. These additives also have a positive effect on increasing the degree of humification of organic substances. Moreover, with an increase in the amount of additives, the degree of humification of organic substances increases. So, in composts without the addition of mineral fertilizers, i.e. with the ratio of manure: PR: (NH2)2CO: KCl = 100: 10: 0: 0, the degree of humification of organic substances was 67.75%, and with the addition of 4% carbamide and 2% potassium chloride, the degree of humification of organic substances was 72.47% .Highlights: - Compost was prepared by mixing manure with phosphate rock and adding various mineral fertilizers. Their composition was studied and the optimal conditions for obtaining complex organomineral fertilizers containing humic substances, nitrogen, phosphorus, potassium and other macro- and microelements in a balanced ratio were determined.