The traditional production process of phosphate fertilizers can generate high amounts of residues with appreciable amounts of P that represent a subutilization of the phosphate rock. With the objective of utilizing these residues the Humifert process was created and consists in the nitric acid treatment of a mixture of phosphatic (low or high contents of P) and organic materials in a chamber, with the goal of increasing P solubility and the agronomic effectiveness (AE). The present work has the objectives of generating information relative to the organophosphate compounds from the process. Several tests were applied as related to the operating conditions of the equipment. Two agronomic experiments were conducted. The first experiment tested the Patos de Minas phosphate rock (PR) and organic matter, submitted or not to the Humifert process, with maize as the testing crop. The second experiment used the P sources Arad PR and Tapira residue, and organic matter, also submitted or not to the Humifert process. As to test also the residual effect of the diverse P sources the testing crops were now corn followed by three successive harvests of brachyaria grass. In both experiments the dry-matter yield (DMY) of the crops were evaluated by mean statistics. In the first experiment the MCP lead to higher DMY and the mixture PMT was superior to the control. In the second experiment, although also the MCP was superior in the first crop (maize) in the overall of all harvests the Arad PR was equal to the MCP. Although some advantages in terms of increase in DMY due to the Humifert process, the solubility and agronomic results indicate that more research is necessary as to adequate the reaction to obtain better quality P sources.
alternative sources; phosphate fertilizers; organic matter
