LOCATION SOGI AS PBEstablished Series
TAXONOMIC CLASS: Medial over ashy, amorphic, isohyperthermic Eutric Hapludands
TYPICAL PEDON: Sogi clay loam - on a 1 percent slope in a cultivated field. When described the soil was moist throughout. (Colors are for moist soil unless otherwise stated. Textures are apparent field textures.)
Ap--0 to 10 inches; dark brown (7.5YR 3/2) clay loam, yellowish brown (10YR 5/4) dry; strong very fine subangular blocky structure; hard, friable, sticky and plastic; common roots; many pores; slightly acid (pH 6.4); gradual wavy boundary. (4 to 12 inches thick)
Bw--10 to 21 inches; dark brown (7.5YR 3/2) clay loam, yellowish brown (10YR 5/6) dry; strong medium and fine subangular blocky structure; friable, sticky and plastic; few roots; many very fine pores; neutral (pH 6.6); abrupt wavy boundary. (7 to 15 inches thick)
2C--21 to 26 inches; very dark grayish brown (10YR 3/2) loamy sand, brown (10YR 4/3) dry; single grain; soft, loose, nonsticky and nonplastic; neutral (pH 6.8); abrupt wavy boundary. (5 to 15 inches thick)
2R--26 inches; very dark brown (10YR 2/2) very strongly cemented tuff.
TYPE LOCATION: Tutuila Island, American Samoa; the site is on Taputimu Farm, about 200 feet southwest of the office complex and 70 feet south of boundary fence; lat. 14 degrees 21 minutes 36 seconds S. and long. 170 degrees 46 minutes 34 seconds W.
RANGE IN CHARACTERISTICS: Depth to a lithic contact with tuff ranges from 20 to 40 inches.
The A horizon has hue of 7.5YR or 10YR, value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist, 3 through 6 dry. It has moderate to strong subangular blocky structure.
The B horizon has hue of 7.5YR or 10YR, value of 2 or 3 moist, and chroma of 2 through 4 moist. It has moderate to strong subangular blocky structure. The lower part of the B horizon is sandy clay loam in some pedons.
The C horizon has hue of 4YR through 10YR, value of 2 or 3 moist, 4 or 5 dry, and chroma of 1 through 4 moist, 3 through 8 dry. It commonly is loamy sand or sand.
COMPETING SERIES: This is the Puapua series in another family. Puapua soils have a lithic contact at depths of 10 to 20 inches.
GEOGRAPHIC SETTING: Sogi soils are on nearly level uplands to steep drainageways and mountainsides. Slope is 0 to 40 percent. These soils formed in volcanic ash and are underlain by hard tuff at depths of 20 to 40 inches. Elevation is near sea level to 600 feet. The mean annual rainfall is 120 to 160 inches, and the mean annual temperature is about 80 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Iliili, Oloava, Pavaiai, and the competing Puapua soils. Iliili and Pavaiai are medial-skeletal and are underlain with lava. Oloava soils have soft weathered cinders in the control section.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderately rapid permeability, except it is slow in the underlying tuff.
USE AND VEGETATION: These soils are used mainly for subsistence farming and homesite. Taro, breadfruit, banana, and coconut are the principal crops grown. Cassava and vegetable crops such as cucumber, beans, cabbage, pepper, eggplant, and tomato are grown in small areas.
DISTRIBUTION AND EXTENT: Southwestern part of Tutuila Island. The soils of this series are of small extent, about 1200 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: American Samoa, 1982.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Umbric epipedon - from the surface to 21 inches. (A and Bw horizons)
Andic soil properties from the surface to 26 inches (A, Bw and 2C horizons.)
Lithic contact at 26 inches (2R horizon.)
Taxonomic Version: Second edition Soil Taxonomy, 1999.
ADDITIONAL DATA: Laboratory data are available on the series type location; pedon number S81AQ-603-001 NRCS National Soil Survey Lab.