effects of thermal phosphates on a dark red latosol chemical properties and their agronomic efficiencies were evaluated in a pot experiment with three consecutive lettuce crops, at the soil science department/fca-unesp, botucatu, state of s？o paulo, brazil. treatments, along with a control check (without fertilizer), consisted of applications to soils of 200 mg p/dm3 as superphosphate, fine and coarse thermophosphate (with micronutrients) and thermophosphate-mg. soil samples were collected, for chemical anaylisis, from all pots before each lettuce transplanting and after last harvest. p, ca and mg soil availabilities after coarse thermophosphate dressing were overestimated by the ion exchange resin methodology. coarse thermophosphate was not effective in reducing soil acidity, while fine thermophosphate increased soil ph value. due to lower solubility, coarse thermophosphate applications resulted in lower lettuce yields and fertilizer efficiencies than those of fine thermophosphate.