Formas de fósforo no solo sob utilização de estimulador microbiológico

Abstract

Phosphorus (P) is essential for plants, so the maintenance of their availability in the soil is fundamental, which occurs mainly with soluble mineral fertilization. However, the indiscriminate use of phosphate fertilization can cause environmental problems, especially eutrophication of surface water resources. To minimize the use of soluble phosphate fertilizer, the use of P in less labile forms should be improved. In this sense, some companies have developed a soil biostimulator that promises to solubilize the P in organic and inorganic forms of lower lability. The objective of this work was to evaluate the phosphorus forms in the soil under the use of a microbiological stimulator. The work was developed in UTFPR-DV, on a Red Nitosol under SPD. In May of 2015 the treatments were: (0% p without Bio) soil under SPD without application of the treatments, (0% P + Bio) 0% mineral phosphate fertilization, with application of biostimulator, (50% P + Bio) (100% P without Bio) 100% of the recommended dose of mineral phosphatic fertilizer, with application of the biostimulator, (100% P + Bio) 100% of the recommended dose of mineral phosphate fertilization, with application of the biostimulator, Phosphate mineral fertilization, without application of the biostimulator. In March 2016 soil samples were collected in the 0-5 and 5-10 cm layers, which were dried, ground and sieved and subjected to the chemical fractionation of P as Hedley et al. (1982), with the modifications proposed by Condron et al. (1985). The data concerning the P content were submitted to analysis of variance and for the significant effects the means were compared by the Tukey test at 5% probability. In the 0-5 cm layer the inorganic and organic labile forms of P were larger than those observed in the 5-10 cm layer, which shows that the P is slightly mobile in the soil profile. It is also verified that the labile forms of P in the 0-5 cm layer varied according to the use of phosphate fertilization, but did not respond to the use of the biostimulator. On the other hand, the use of the biostimulator elevated the moderately labile inorganic forms of the soil from the 0-5 cm layer, while decreasing the moderately labile organic forms. Both the phosphate fertilization and the biostimulator did not interfere in the total, geochemical and biological P content of the soil. Based on the obtained data, it is concluded that the effect of soluble phosphate applied to the surface is restricted to the first 5 cm of the soil, where it mainly elevates the inorganic labile forms of P. The use of the biostimulator raises the moderately labile inorganic forms of the soil, Due to the mineralization of the moderately labile organic forms, especially when associated with the use of mineral phosphate fertilization.