Ciencia del suelo
versão On-line ISSN 1850-2067
Phosphorus (P) fertilization modifies the balances between the different forms of soil P, altering P availability and plant uptake. The objectives of this study were to determine the influence of some soil properties on the P rate required to increase a unit of extractable phosphorus (De) and the effect of P application on wheat (Triticum aestivum L.) dry matter production, crop response and the balance with other nutrients. A wheat fertilization pot experiment was carried out with P rates of 0, 25, 50 and 100 kg ha-1 using nineteen different soils (sampled at a 0-0.20 m-depth). Extractable P (Pe) was determined at the beginning of the experiment and at the time of plant sampling (heading complete). Total N, P, K, S were determined in plant and the P balance with other nutrients was calculated. DRIS methods were also determined. Average De was 2,7 kg P ha-1 per mg Pe kg-1 soil (with values between 1,2 and 4,8). Initial Pe and organic matter associated with the mineral fraction (MOM) were the properties that best explained De variability. Dry matter and P concentration in plant increased with P rate. These changes were associated with initial Pe, which was, in turn, reflected in the nutrient balance. Concentration of other nutrients in plant (N, K and S) was not modified by P fertilization, but total quantity increased significantly. In conclusion, the factors that affect P dynamics and the fate of applied P were the P physical - chemical balances and the soil characteristics, especially Pe and MOM. Concerning the crop, P fertilization modified P uptake and the balance with other nutrients.
Palavras-chave : Phosphorus; DRIS; Dry matter.