Korean Journal of Soil Science and Fertilizer ISSN:0367-6315(Print) 2288-2162(Online) 한국토양비료학회 학회지

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 was conducted to classify Ora and A Ora series based on the second edition of Soil Taxonomy and to discribe the formation of Ora and A Ora series in Jeju Island. Morphological properties of typifying pedons of Ora and A Ora series were investigated and physico-chemical properties were analyzed according to Soil Survey Laboratory Methods Manual. The typifying pedon of Ora series established in the nothern mid-mountainous areas in Jeju Island has an umbric epipedon from a depth of 0 to 35 cm and a cambic horizon from a depth of 35 to 92 cm. That can be classified as Incepisol. It has an udic soil moisture regime and keys out as Udept. It has an umbric epipedon and keys out as Humudept. It has, throughout one or more horizons with a total thickness of 18 cm or more within 75 cm of the mineral soil surface, a fine-earth fraction with both a bulk density of 1.0 Mg m^-3 and Al plus 1/2 Fe percentages (by ammonium oxalate) totaling more than 1.0. It can be classified 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 Andic Humudept, not as fine silty, thermic family of Andic Eutrudept. The typifying pedon of A Ora series set up in the southern mid-mountainous areas in Jeju Ialand has an umbric epipedon from a depth of 0 to 42 cm and a cambic horizon from a depth of 42 to 101 cm. That contains oxalate extractable (Al + 1/2Fe) content equal to 2.0 or more, phosphate retention of 85% or more, and bulk density of 0.90 Mg m^-3 or less from a depth of 0 to 160 cm. Therefore, it has an andic soil properties at that depth. It can be classified as Andisol. It has an udic soil moisture regime, and can be classified as Udand. Also it meets the requirements of Typic Hapludand. It has medial particle-size class, ferrihydritic mineralogy class, and thermic soil temperature class. Therefore it can be classified as medial, ferrihydritic, thermic family of Typic Hapludand. Ora series distributed in the northern and western mid-mountainous areas are classifyed as Inceptisols. But A Ora series distributed in the southern mid-mountainous areas are classifyed as Andisols. A Ora series distributed in the southern mid-mountainous areas in Jeju Island are established as Hoesu series, new series. In the western and northern coastal areas which have a relatively dry climate in Jeju Island, non-Andisols are widely distributed. Mean annual precipitation is increased and mean annual temperature is decreased remarkably with increasing elevation. In the western and northern mid-mountainous areas Andisols and non-Andisols are distributed simultaneously. Ora series distributed in the western and northern mid-mountainous areas are developed as Andic Humudepts. Hoesu series distributed in the southern mid-mountainous areas which have a humid climate are developed as Andisols.

Laboratory data sheets of typifying pedons of Ora and Hoesu series.