Taxonomical Classification and Genesis of Hoesu Series, New Series in Jeju Island

Typifying pedon of Ora series distributed in the northern mid-mountainous areas and that of A Ora (Hoesu)series distributed in the southern mid-mountainous areas in Jeju Island were established. This study wasconducted to classify Ora and A Ora series based on the second edition of Soil Taxonomy and to discribe theformation of Ora and A Ora series in Jeju Island. Morphological properties of typifying pedons of Ora and AOra series were investigated and physico-chemical properties were analyzed according to Soil SurveyLaboratory Methods Manual. The typifying pedon of Ora series established in the nothern mid-mountainousareas in Jeju Island has an umbric epipedon from a depth of 0 to 35 cm and a cambic horizon from a depth of35 to 92 cm. That can be classified as Incepisol. It has an udic soil moisture regime and keys out as Udept. Ithas an umbric epipedon and keys out as Humudept. It has, throughout one or more horizons with a totalthickness of 18 cm or more within 75 cm of the mineral soil surface, a fine-earth fraction with both a bulkdensity of 1.0 Mg m-3 and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling more than 1.0. It can beclassified by Andic Humudept. The typifying pedon has medial particle-size class, mixed mineralogy class,and thermic soil temperature regime. Therefore, it can be classified as medial, mixed, thermic family of AndicHumudept, not as fine silty, thermic family of Andic Eutrudept. The typifying pedon of A Ora series set up inthe southern mid-mountainous areas in Jeju Ialand has an umbric epipedon from a depth of 0 to 42 cm and acambic horizon from a depth of 42 to 101 cm. That contains oxalate extractable (Al + 1/2Fe) content equal to2.0 or more, phosphate retention of 85% or more, and bulk density of 0.90 Mg m-3 or less from a depth of 0 to160 cm. Therefore, it has an andic soil properties at that depth. It can be classified as Andisol. It has an udicsoil moisture regime, and can be classified as Udand. Also it meets the requirements of Typic Hapludand. Ithas medial particle-size class, ferrihydritic mineralogy class, and thermic soil temperature class. Therefore itcan be classified as medial, ferrihydritic, thermic family of Typic Hapludand. Ora series distributed in thenorthern and western mid-mountainous areas are classifyed as Inceptisols. But A Ora series distributed in thesouthern mid-mountainous areas are classifyed as Andisols. A Ora series distributed in the southernmid-mountainous areas in Jeju Island are establ