This paper reports the results obtained in four experiments with potatoes, which were conducted from 1948 to 1950 in two locotities of the State of São Paulo and designed to compare superphosphate with bane meal and bauxite (a phosphorous bauxite from the State of Maranhão, Brazil) in the presence of nitrogen and potassium. A dose of 120 kilograms of P2O5 to the hectare was opplied either exclusively as the mentioned types of phosphates or as mixtures containing half the amount of phosphorus in the form of superphosphate and half in that of bone meal or bauxite. When used as the only source of phosphorus, bone meal and bauxite were as a rule much inferior to superphosphate; on the other hand, the results obtained indicate thate there is no economical advantage in using the studied mixtures of phosphates instead of superphosphate.