PHOSPHORUS SOURCES FOR SUGARCANE FORAGE CULTIVARS FERTILIZATION IN THE BRAZILIAN SAVANNAH

Due to the expansion of sugarcane in areas of Cerrado (Brazilian savannah), it is necessary to study the fertilization management, mainly for phosphorus (P), since it is the nutrient that most limits yield, in this ecosystem. The aim of this study was to compare the effect of phosphorus sources over two sugarcane cultivars. The study was carried out in Alta Floresta, Mato Grosso State, Brazil, in a Hapludox soil. The experimental design was randomized blocks, in a 4x2 factorial scheme, being evaluated the effect of P sources (bone flour, Arad phosphate, and triple superphosphate), at a 100 kg P2O5 ha-1 dose, a control without nutrient application, and the IAC 86 2480 and SP 79 1011 cultivars, with four replications. Plant height, stem diameter, tiller number, yield (fresh and dry matter), P content efficiency on the plant, P extraction, and economic viability were evaluated for selecting source and ºBrix. Phosphorus fertilization affected plant number and height, P concentration, and fresh and dry matter yield. Concerning the sources studied, similar results were found, but with higher efficiency for bone flour, which increased the P concentration and extraction, as well as economic viability. The IAC 86 2480 cultivar showed higher averages than the SP 79 1011, for all parameters evaluated. KEY-WORDS: Saccharum officinarum; plant-cane; phosphate fertilization; bone flour.