EFFECT OF PHOSPHORUS APPLICATION AND OF I TS RESIDUE ON THE YIELD OF SUGARCANE IN A VERTISOL

This work, carried out at Juazeiro, BA, Brazil, aimed at evaluating th e effects of 0, 60, 120, 180, 240 and 300 kg/ha of P2O5 on the yield, on some technological characteristics of sugarcane and on the residual effect of phosphorus. In all plots, 180 kg/ha of N and 90 kg/ha of P2 O5 were applied. After harvesting the sugarcane, half of each plot was fertilized with 90 kg/ha of P2O5 and all the subplots received 150 kg /ha of N and 90 kg/ha of K2O. The leaves of 120 day-old plants were an alyzed for phosphorus. At harvesting time, the P contents and the pol (%) were determined in the sugarcane juice. The P levels showed a quad ratic effect on the yield of sugarcane (R(2) = 0.94) and on the P conc entration in the leaves (R(2) = 0.98). The yield of sugarcane in the t reatments that did not receive a second application of phosphorus vari ed from 45.31% to 78.93%, as compared to the treatments that had recei ved 90 kg/ha of P2O5. Phosphorus concentration in the juice increased with the levels of phosphorus applied. The pol (%) of the juice, howev er, was not affected.