The São Paulo cotton varieties IAC 13-1, IAC 16 and IAC 17 were studied in a permanent field trial on a Latosolic B Terra Roxa soil, of low fertility, during the years of 1974/75, 1975/76 and 1976/77. They received different levels of simple superphosphate, namely 0, 225, 450 and 675kg/ha. The experimental design was a split plot, with four replications, containing superphosphate fertilizations on the main plots and varieties on split plots. Lime was applied before the first year of cropping and annual applications of 50kg/ha of N and 75kg/ha of K2O were made, on all plots. After three years of fertilization a soil analysis showed increases in phosphorus and calcium levels. The leaf blade calcium concentration was significantly increased by the use of superphosphate, while potassium concentration was decreased. Phosphorus and magnesium levels were also favorably influenced. The potassium content appeared to be negatively correlated with calcium and magnesium. The concentrations of N, S, P, Ca and K in the IAC 17 leaf blade were higher than those observed for IAC 13-1 and IAC 16. In the first year cropping a negative net income was observed, due to low responses to fertilization and to unfavorable cotton price. Because of the high levels of net, income obtained in the second and third year, it seems that, for future studies, the use of higher amounts of superphosphate, and new application methods need to be recommended. IAC 17 cotton showed through the years the highest capacity of utilization of simple superphosphate.