A Study on Pedogenesis and Characteristics of Red-Yellow Soils in the Philippines : I. Morphology, physico-chemical properties and classification

抄録

A study was conducted to determine the characteristics of six upland Red-Yellow soils in relation to soil-forming factors such as climate, topography and parent material, and to calssify them based on U.S.D.A. Soil Taxonomy and FAO-Unesco system. Results showed that the variations in the physical properties of the different soil samples appear to be influenced by the nature of the parent material. On the otherhand, the variation of soil chemical properties, particularly cation exchnge capacity and base saturation may be largely attributed to the differences in topography and climatic type. On drier area, Typic Rhodustalf (Rhodic Acrisol) developed on upper terrace while Typic Haplustalf (Haplic Luvisol) formed on lower terrace. For very humid areas, Typic Kandiudult (Haplic Nitisol with low base saturation) developed on mid-slope, while on flat area or terrace, Typic Kandiudalf (Haplic Nitisol with high base saturation) was formed. For soils derived from volcanic pyroclastic under humid condition, Alic Hapludand (Haplic Andosol) developed on mid-slope while Ultic Hapludand (Haplic Andosol) developed on foot-slope.