Properties, geochemical composition, and fertility of highly weathered soils in Central Philippines

Highly weathered soils are widepsread in the humid tropics. These deep, clayey, and reddish contain scant amounts of nutrients like Si due to excessive leaching, heavy desilication-aluminization, erosion owing their slope gradient position. However, few investigations have been published terms nature, characteristics, nutrient status, especially for geologically young Philippine islands. This study assessed properties, geochemical composition, fertility deep highly developed from various parent materials Central Philippines (Leyte Samar). Sampling covered entire soil profiles, including lower portions, that usually neglected common characterization studies. Among only profiles 3 8 non-uniform or heterogeneous materials. Findings likewise revealed losses K2O, CaO, MgO, Na2O evaluated. The amount profile distribution K2O CaO is below 0.5% most soils. On other hand, there apparent enrichment Al2O3, Fe2O3, a lesser extent SiO2 thus supporting residua hypothesis. In morpho-physical solum, color, subangular structure, friable moist consistence, sticky plastic wet consistence which all related nature They also generally low bulk density higher porosity iron oxides aggregation effect. strong acidity (pH <5) negative delta pH values colloids possess net charge. Nutrient status showed contents organic matter, total N, available P, exchangeable bases. Majority evaluated possibly homogenous classified as Hapludox, Hapludult, Paleudult.