The study was conducted at the Greenhouse of the Department of Soil Science, University of the Philippines at Los Baños, Laguna to evaluate some properties of an acid sulfate and ordinary acidic mineral soils, to determine the effects of liming and phosphorus application on the soil solution and sorbed phosphorus, and to assess the effects of liming and phosphorus fertilization on the yield, soil chemical properties and nutritional status of corn and rice grown on these two soils. The major soil chemical properties causing poor crop growth on the acid sulfate Castanas silty clay in contrast to Lipa clay were extremely low pH (pH 3), very high SO4 (7612 ppm) and exchangeable Fe (2400 ppm), high exchangeable Mn (127 ppm) and Al (2 me/100 g) and very low exchangeable K (0.03 me/100 g). Calcium was low (9.3 me/100 g) relative to the CEC of 28 me/100g while the Bray P2 14.6 ppm was moderate. Exchangeable Mg was satisfactory in both acidic soils.
