Residual effects of calcium amendments on oil palm growth and soil properties

Abstract

Residual liming is one of the measures of the efficacy of liming materials. Ca2+- amendments such as calcium hydroxide (Ca(OH)2), calcium oxide (CaO) and calcium carbonate (CaCO3) in soils may contribute to plant growth response in plant height and total dry matter yield of oil palm seedlings. The increasing of other essential elements such as nitrogen (N), phosphorus (P) and ions of potassium (K+) also play a great role in the plant growth and crop yield, conversely, the soil pH and ions of aluminium (Al3+) will inhibit the plant growth and crop yield. This main aim this experiment is to determine the residual liming effect of Ca2+-amendments to highly acidic soils collected from Jeram and Bungor series, Malaysia, which also contains 2 times of Al3+. The highly acidic soils of previously planted with oil palm seedlings initially incubated with selected Ca2+-amendments along with Mg2+- amendments such as, dolomite (CaMg.CO3) for 360 days and, kept for additional 180 days before planting for a total of 540 days in a greenhouse environment. In this experiment, the soil chemical analysis, plant growth response, and the possible mechanisms responsible for the Ca2+-amendment liming effects were measured. The results of the soil chemical analysis showed that Ca2+-amendment residues potentially reduced the soil acidity than Mg2+- amendments. Ca(OH)2was the most prominent Ca2+-amendment to increase soil-water pH, soil solution pH, and concentrations of soluble Ca2+and K+. While, concentration of soil solution and exchangeable Al were effectively reduced 540 days after the application of Caamendments. The dry shoot weight of the oil palm seedlings improved about 1.67 g/pot and 16.87 g/pot in control and Ca2+-amendment treatments, respectively. In this study, it has showed that the root dry weight of oil palm seedlings increased from 0.18 g/pot to 4.49 g/pot in pot and Ca2+-amended soil, respectively. Increased plant height and total dry matter yield of oil palm seedlings grown on the Ca-amended soils may be attributed to increased soil pH which resulted in lowered concentration and activity of soluble AI, and increased concentrations of soil solution Ca and K which were released of Ca. This finding concluded that the possible mechanisms of Ca2+-amendments from residual liming might be: a) complexation interaction between Al3+and Ca2+; (b) capacity of Ca-amendments to increase the concentration of Ca to maintain soil desired pH; (c) alleviation effect of Ca-amendments to reduce Al toxicity concentration in the soil. Last but not least, this finding showed that dry matter yield and plant height positively associated with the presence of Al3+in both soil conditions.