An experiment was carried out, in pots, to study the effects of phosphate fertilizers (ordinary superphosphate, thermal phosphate and rok phosphate) on both, the pH and the amount of exchangeable Al3+ in two soils (Orthic Haplacrox and Orthic Hapludent) from the municipality of Piracicaba, State of São Paulo, Brazil. Thermal phosphate reduced the active and exchangeable acidities in both soils. Rock phosphate and ordinary superphosphate reduced the exchangeable acidity but caused very little effect on the pH of the soils .
Soil acidity; soil pH; exchangeable acidity