Based on growth response of Desmodium intortum, a tropical forage legume with a relatively high Ca requirement and low Al tolerance, it was demonstrated that soil acidity can be corrected by either Ca(OH)2 or organic manure additions. Both lime and manures raised soil pH and inactivated Al. In terms of pH increases, 5 and 10 g chicken manure kg^-1 were equivalent to 3.4 and 6.7 cmolc kg^-1; and 20 g sludge kg^-1, equivalent to 6.5 cmolckg^-1 as Ca(OH)2. The manures also detoxified soluble Al by organic complexation and enhanced Ca uptake of the Desmodium. The plant's maximum growth required at least 1.0% Ca in leaves, and this growth was reduced by half when leaf Al > 76 mg kg^-1 and soil-solution Al³⁺ activity > 4 M.