Morpho-physical and Chemical Characteristics of Strongly Weathered Soils in Silago, Southern Leyte, Philippines

Abstract

The study evaluated the morpho-physical and chemical characteristics of strongly weathered soils in Silago, Southern Leyte, one of the biodiversity hotspots in the Philippines. Examination of seven soil profiles revealed that the soils have colors ranging from yellowish brown to yellowish red, have high clay content (37.04 to 62.15%), and moderate to high porosity values (38.49 to 52.83%). They are deep (>3 m) and friable when moist but very plastic and very sticky when wet. In terms of soil chemistry, most of the soils have acidic pH values (<6.75), have low to moderate potential CEC (11.31 to 38.13 cmol_c /kg), low to high base saturation (0.76 to 69.62%), and extremely low to medium organic matter content (0.07 to 2.59%). The soils contain low to medium N (0.01 to 0.28%), and extremely low available P (< 5 mg/kg). However, most of the soils contain sufficient amounts of exchangeable Mg (0.12 to 9.28 cmol_c/kg), and Na (0.05 to 1.70 cmol_c /kg) except profile 5, but are deficient in Ca (0.07 to 0.27 cmol_c/kg) and exchangeable K (0.02 to 0.37 cmol_c/kg)since the soils are acidic. Most of the soils are classified as Hapludults (USDA Soil Taxonomy) or Haplic Alisols (WRB) except the one in the toeslope which is a Hapludalf or Haplic Luvisol. The study revealed that the soils have closely related properties probably due to their similar parent material, original forest vegetation and climate. The differences in some soil properties appear to be the effect of topography.