Effects of lime and organic matter on soil acidity, aluminum, phosphorus and growth of corn and mungbean on two acidic soils.

Screenhouse experiments were conducted to determine the effects of lime and organic matter application on soil acidity, aluminum, phosphorus, nutrient status and growth of mungbean and sweet corn on Antipolo sandy clay and Luisiana sandy clay soils, and to determine the influence of zinc and boron fertilization on the alleviation of poor crop growth in heavily limed soils. The Antipolo and Luisiana sandy clay soils are highly weathered, aluminous ultisols. These are strongly acidic (pH 4.6 and 4.9, respectively), with high exchangeable Al (3.2 and 2.1 meq/100 g), high Al saturation (44.5 and 23.4%), high exchangeable acidity (4.0 and 2.4 meq/100 g), and very low available P (2.62 to 2.39 ppm). The addition of lime and organic matter significantly increased the pH, CEC and available P, but decreased significantly the exchangeable Al, solution Al and Al saturation. Liming rates beyond 5 tons CaCO3/ha on Antipolo sandy clay and 3.0 tons/ha on Luisiana sandy clay decreased the exchangeable Al to zero and these also diminished the available P, exchangeable K, and Mg. In contrast, the availability of N, P, K Mg were increased with increased levels of organic matter in both soils. Most of the soil chemical properties were optimum for plant growth at 8% organic matter and 5 tons CaCO3/ha on Antipolo sandy clay, and 6% organic matter and 3.0 tons lime/ha on Luisiana sandy clay. On Antipolo sandy clay, the lime rates that produced maximum dry matter yields of corn and mungbean were 5.3 and 6.0 tons lime/ha, respectively. On Luisiana sandy clay 3.1 and 3.5 tons lime/ha respectively, produced maximum dry matter yields of corn and mungbean. An Antipolo sandy clay optimum growth of corn and mungbean were obtained at pH 5.3 and 6.1, respectively, while on a Luisiana clay the pH required for optimum growth for practical purposes were the same at 5.3 and 6.0, respectively. The application of 9.0 tons CaCO3/ha on Antipolo sandy clay and 5.0 tons CaCO3/ha on Luisiana sandy clay produced zinc deficiency symptoms on both crops. This problem was corrected by the application of a high rate of zinc.