Sources of phosphorus for sugar cane (1961-63)

Five experiments were conducted in the State of São Paulo to study the efficiency of different sources of phosphorus for the production of sugar cane on three types of soil, using 50, 100 and 150 kilograms of total P2O5 per hectare in the presence of NK. The soil pH varied from 4.8 to 5.6. Phosphorus significantly increased the yields in all of the experiments. As an average of the five experiments and the three rates of application, the per-cent yield increases caused by the studied phosphorus carriers were the following: thermophosphate, 49; dicalcium phosphate, 39; bone meal, 38; ordinary superphosphate, 35; Alvorada-phosphate, 28; Olinda-phosphate, 26; Araxá-phosphate, 20; phosphorous bauxite, 10. The four latter sources are natural phosphates from different regions of Brazil.