Agribusiness is one of the most important economic activities of the Brazil. The high level of Brazilian productivity agriculture is due of the adequate preparation of the soil, which must be fertile and slightly acidic. The replacement of nutrients is necessary; therefore, the costs with fertilizers are high. Phosphorus is an important element to the growth of any vegetable, which is classified as a macronutrient, because is required in large quantity. The Brazil present deficit this nutrient and imports about 50% of what is consumed. Alternative sources are being studied, as well as their by-products after chemical and/or thermal treatments. In general, the cost for characterization and classification of phosphate materials is high, mainly due the complexity of mineralogical assemblages and/or thermochemical transformations. Thus, the aim of this research was determine parameters of phosphate differentiation using infrared spectroscopy, a practical, quick and relatively cheaply technique, using six different phosphate varieties. Sample preparation, measurement and analysis conditions were studied for Near and Middle spectral regions. The results revealed that for both spectral regions, the most adequate resolution was 8 cm-1; the filling mode of the sample holder for diffuse reflectance measurement (DRIFT) must be the random form. When it was compared spectra between random and oriented, the oriented preparation form did not cause significant damage in the Near region, thus, for practicality, this method may be chosen. The best resolutions of the bands in the Middle region was using sample diluted in KBr, whether in DRIFT or TRANSMITANCE mode, which was better than those obtained by ATR mode. The development of a concise and more detailed database for phosphate materials was established, and the information in the constructed library goes beyond of the information about the position band concerning the phosphatic functional groups. The spectrometric profile registered can help to obtain details about microstructure of the phosphate and of the assembly of phases present.
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