LOCATION PAVAIAI AS PBEstablished Series
TAXONOMIC CLASS: Medial-skeletal, amorphic, isohyperthermic Eutric Fulvudands
TYPICAL PEDON: Pavaiai stony clay loam - on an 8 percent slope along a road. When described the soil was moist throughout. (Colors are for moist soil unless otherwise stated. Textures are apparent field textures.)
A1--0 to 7 inches; very dark grayish brown (10YR 3/2) stony clay loam, very dark grayish brown (10YR 3/2) dry; strong fine and very fine subangular blocky structure; hard, friable, sticky and plastic; many roots; many pores; 2 percent pebbles and 10 percent stones; slightly acid (pH 6.2); clear smooth boundary.
A2--7 to 12 inches; very dark grayish brown (10YR 3/2) clay loam, brown (10YR 4/3) dry; weak fine and medium subangular blocky structure; slightly hard, friable, sticky and plastic; common roots; many very fine and few fine pores; 5 percent pebbles; moderately acid (pH 6.0); gradual smooth boundary. (Combined thickness of A horizons is 7 to 12 inches)
Bw1--12 to 26 inches; dark brown (10YR 3/3) very cobbly sandy loam, dark yellowish brown (10YR 3/4) dry; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common roots; many very fine and few fine pores; 5 percent pebbles, 25 percent cobbles, and 15 percent stones; slightly acid (pH 6.2); abrupt smooth boundary. (5 to 14 inches thick)
Bw2--26 to 38 inches; dark brown (10YR 3/3) very cobbly sandy loam, dark yellowish brown (10YR 3/4) dry; weak fine and medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; few roots; many very fine and few fine pores; 5 percent pebbles, 35 percent cobbles, and 15 percent stones; slightly acid (pH 6.3); abrupt smooth boundary. (5 to 16 inches thick)
2R--38 inches; pahoehoe lava.
TYPE LOCATION: Tutuila Island, American Samoa; at Mapusagafou 0.4 mile north of Pavaiai intersection on cut at M&J Enterprise; lat. 14 degrees 21 minutes 4 seconds S. and long. 170 degrees 45 minutes 4 seconds W.
RANGE IN CHARACTERISTICS: The thickness of the solum and depth to bedrock range from 20 to 40 inches. The control section is 35 to 55 percent rock fragments. It is medium acid to neutral.
The A horizon has value of 2 or 3 moist, 3 or 4 dry, and chroma of 2 or 3 moist or dry. It commonly is clay loam and less commonly silty clay loam. Rock fragment content is 5 to 35 percent.
The B horizon has value of 2 or 3 moist, 3 or 4 dry, and chroma of 2 or 3 moist, 3 or 4 dry. The fine earth fraction commonly is sandy loam or sandy clay loam, but the range includes silty clay loam, clay loam, and very fine sandy loam. Rock fragments range from 40 to 60 percent.
COMPETING SERIES: This is the Iliili series in another family. Iliili soils have a lithic contact within a depth of 20 inches.
GEOGRAPHIC SETTING: Pavaiai soils are on sloping to steep uplands. Slope is 6 to 40 percent. These soils formed in volcanic ash and are underlain with dense lava at depths of 20 to 40 inches. Elevation is near sea level to 900 feet. The mean annual rainfall is 150 to 200 inches, and the mean annual temperature is about 79 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Leafu, Oloava, Puapua, Sogi, and the competing Iliili soils. Leafu soils formed in alluvium on valley floors. Oloava soils have soft weathered cinders in the control section. Puapua soils are underlain with hard volcanic tuff within depths of 20 inches. Sogi soils are ashy in the lower part of the control section.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderately rapid permeability.
USE AND VEGETATION: These soils are used for subsistence farming, homesite, and woodland. The main crops are taro, banana, breadfruit, coconut, and cassava. Small areas are used for vegetable crops. Areas not cultivated are in tropical forest.
DISTRIBUTION AND EXTENT: Islands of Tutuila and Tau. The soils are of small extent, about 2100 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 a depth of 38 inches (0 to 97 centimeters) (The A and Bw horizons).
Properties of a melanic epipedon, except color - from 0 to 12 inches (0 to 30 centimeters (The A horizon)
Andic soil properties - 0 to 38 inches (0 to 97 centimeters) (The A and Bw horizons).
A lithic contact at 38 inches (97 cm) (2R horizon)
Perudic moisture regime
Taxonomic Version: Second edition Soil Taxonomy, 1999.
ADDITIONAL DATA: This pedon number S81AQ-603-014 was sampled and analysis was performed by the SCS National Soil Survey Lab in 1981. A second pedon (S81AS-603-058 fits the series except has too little organic matter to be a Fulvudand and averages less than 35 percent rock fragments in the particle-size control section.