The use of waste from sugarcane industry as a source of nutrients for the crop itself has become increasingly important in the production chain of cane sugar, being an environmental and economic alternative to cycling these residues, since these materials are rich in nutrients such as N, P, K, and other elements essential. Plant and animal residues are materials for the production of organic fertilizers. These residues can be used in its "fresh" or receiving treatment, such as composting, turning them into organic-mineral fertilizer, when added mineral sources, such as phosphate rock, in order to improve its quality. The aim of this study was to quantify levels of N, P, K biofertilizer submitted to the composting process. 8 treatments were applied consisting of 2/3 of filter cake and 1/3 of boiler ash and evaluated combinations of phosphate rock (1.4 kg, poultry manure and bacterial inoculum (Pseudomonas and Bacillus) to solubilize the P mineral. The total N was obtained by digestion at 400°C with concentrated sulfuric acid in the presence of copper sulphate and subsequent titration with HCl. The P and K were obtained by digestion KCl, 1 +1 with previous elimination of the organic matter in a muffle furnace at 550 ° C. The determination of P was made in colorimeter and K in spectrophotometer flame. The average content of N was 1.0% and did not differ between treatments. The K levels were higher in the treatments containing poultry manure, with a mean value of 10.6%, and for treatments without manure of 6.8%. The P concentrations were variable among treatments, being higher (17% P) were those where the presence of bacterial inoculants, while the other treatments, the levels were on average 15%.