PROPERTIES AND RELATED MANAGEMENT IMPLICATIONS OF MAJOR SOILS IN BUKIDNON, PHILIPPINES

Abstract

In this study, the soils on the steeplands of Sabacan, Himaya, and San Jose, and on the uplands and alluvial areas of Musuan, were mapped, characterized morphologically and chemically, and classified based on the USDA Soil Taxonomy. The mineralogy of the various soil horizons has been determined using X-ray diffraction (XRD), scanning electron microscopy SEM, and transmission electron microscopy (TEM). The soils in the steepland and upland areas are classified as Typic Hapladalfs and Lithic Dystropepts. The floodplain is occupied by Typic Tropaquepts. The pH of the Ap horizons is moderately acid in Typic Hapludalfs and Typic Dystropepts and strongly acid in Typic Tropaquepts. The apparent cation exchange capacity is very high in these soils, characterized by low contents of organic carbon and total nitrogen, a very low available phosphorus and low base status. XRD analysis showed that gibbsite, quartz, halloysite and hydroxy interlayered 2:1 minerals are present in the clay fraction of all soils. TEM showed goethite as acicular crystals extending into pores like needles and lepidocrocite as highly elongated flakes found abundant in the sub-soils ofTypic Tropaquepts. Typic Hapludalfs are deep, well-drained soils suitable for upland cultivation. Use of light implements would help minimize soil compaction during land preparation, and contour plowing would alleviate soil erosion hazards on these soils. The coarse-textured Lithic Dystropepts, which have a coherent underlying hard rock material at 50 cm of the mineral surface, would require proper drainage. A clayey texture and a massive structure with redoximorphic conditions pose aeration problems in the Typic Tropaquepts. These soils could best be utilized for lowland rice cultivation.