The effects of pH and calcium on the growth ofLeucaena leucocephala in an oxisol and ultisol soil

Leucaena was grown for eleven weeks in a pH and calcium amended oxisol and ultisol to determine whether poor growth in acid soils is related to calcium deficiency or low pH induced effects, such as aluminium toxicity. Soil pH was ameliorated by the addition of either CaCO₃, or SrCO₃, while CaCO₃ or Ca(NO₃)₂ were used to modify calcium supply. In both soils, CaCO₃, and SrCO₃ application resulted in an increase in pH and a reduction in exchangeable aluminium although the response of leucaena to the applied amendment varied between the two soils. In the oxisol there was little effect of increased pH on growth, but a marked response to Ca application. In the ultisol, growth was improved by increasing pH but there was no response to increased calcium. The effects of liming on these soils are discussed in relation to alternative strategies available for utilising leucaena and other tree legumes.