Phosphorus Fractions and Their Transformations in Entisol

The availability of phosphorus in the soil is a factor that directly interferes with its absorption by plants. This availability can be influenced by the texture, dose of the phosphate fertilizer and the time of contact with the soil. This study aimed to quantify the organic and inorganic fractions of P accumulated in a sandy soil receiving doses of phosphorus, incubated and grown with rice. The experimental design was a completely randomized design, in a 4 × 3 factorial scheme, with four replicates, and four P doses (0, 80, 240, and 410 mg dm-3) and three evaluation times (before sowing, after harvest, and incubated). Soil samples were collected before, after incubation, and after rice harvesting, and then submitted to a chemical fractionation of P. P fractions were influenced by soil collection times. The inorganic fractions prevailed before sowing and after incubation, and the organic fractions prevailed after harvest. Phosphate fertilization favored mineralization of organic P and redistributes the inorganic and organic P fractions, between labile and non-labile compartments. The application of phosphate fertilizer in an Entisol Quartzipsamment contributes to the accumulation of inorganic fractions, especially in the most labile fractions.