Characterization and potential of organic and mineral phosphate fertilizer used in the annual agriculture

portugais. The phosphorus fertilization is necessary so that the soil is able to offer ideal conditions for the development of plants. However, phosphate fertilizers differ in their origin, residual effect and efficiency in the availability of nutrients in the soil. The objective was to characterize the origin and sustainability of major mineral and organic phosphate fertilizers, in order to meet the real need for fertilization for some annual crops of commercial interest. Phosphate fertilizers are classified into soluble and natural mineral fertilizers and organic fertilizers. The soluble mineral fertilizers have the major advantage of immediate availability of phosphorus when applied to the soil, and then give quickly the needed for phosphorus to the plants. However they are the main problem the rapid fixing of phosphorus available for adsorption sites, which greatly reduces the residual effect. Thus it has been used natural phosphates that are able to provide nutrient for a longer time because they present more gradual reaction in the soil. However, the problem to have low solubility in soil with high pH H2O (> 5.5). As a strategy, the thermophosphates can be applied, natural fertilizers heat-treatment, which increases efficiency, in addition to having greater residual effect soluble fertilizers. However, mineral fertilizers have as main problem the high cost, which reduces the profitability of the crop. Thus, the strategy employed in agriculture may be from the application of organic fertilizers capable of supplying phosphorus and other nutrients, to ensure a more complete fertilization. Also, they have greater residual effect, which can be an important way of fertilization mainly in clayey soils.