LOCATION FAGASA AS PBEstablished Series
The Fagasa series consists of moderately deep, well drained soils on ridges and mountainsides. These soils formed in residuum of weathered basic igneous rock. Slope is 30 to 130 percent. Elevation is near sea level to 2,100 feet. The mean annual rainfall is about 200 inches, and the mean annual temperature is about 78 degrees F.
TAXONOMIC CLASS: Fine, halloysitic, isohyperthermic Andic Hapludolls
TYPICAL PEDON: Fagasa silty clay - on an 80 percent slope in a taro and banana plantation. When described, the soil was moist throughout. (Colors are for moist soil unless otherwise stated. Textures are apparent field textures.)
A1--0 to 5 inches; very dark grayish brown (10YR 3/2) silty clay, very dark grayish brown (10YR 3/2) dry; moderate fine and medium subangular blocky structure; very hard, firm, sticky and plastic; many roots; many pores; 10 percent cobbles; moderately acid (pH 6.0); clear wavy boundary.
A2--5 to 12 inches; dark brown (7.5YR 3/2) cobbly silty clay, dark brown (7.5YR 3/2) dry; moderate fine and medium subangular blocky structure; very hard, firm, very sticky and very plastic; many roots; many very fine and common fine pores; 10 percent stones and 20 percent cobbles; moderately acid (pH 6.0); clear wavy boundary. (Combined thickness of A horizons is 8 to 12 inches)
BC--12 to 29 inches; dark brown (7.5YR 3/2) silty clay, brown (7.5YR 4/4) dry; moderate fine and very fine subangular blocky structure; very hard, firm, very sticky and very plastic; moderately acid (pH 5.8); 30 percent weathered igneous rock; gradual wavy boundary. (12 to 20 inches thick)
R--29 inches; unweathered igneous rock.
TYPE LOCATION: Tutuila Island, American Samoa; at Pago Pago 2.2 miles from coast highway on road to Fagasa; the site is about 100 feet upslope from the road; lat. 14 degrees 17 minutes 28 seconds S. and long. 170 degrees 42 minutes 31 seconds W.
RANGE IN CHARACTERISTICS: The solum is 20 to 30 inches thick. A Bw horizon is present in some pedons. Lithic[r1] contact is at a depth of 20 to 40 inches. The profile is 0 to 15 percent stones, 0 to 20 percent cobbles, and 0 to 20 percent pebbles,
and average less than 35 percent rock fragments at depth of 10 to 40 inches. It is medium acid to slightly acid.
The A horizon has hue of 7.5YR or 10YR, value of 3 or 4 dry, and chroma of 2 or 3 moist or dry. It commonly is silty clay and less commonly clay.
The BC horizon has hue of 7.5YR or 10YR, value of 3 or 4, and chroma of 2 through 4 moist or dry. It is silty clay or clay loam.
COMPETING SERIES: These are the Ofu series in the same family and the Aua series. Ofu and Aua soils lack a paralithic contact within depths of 40 inches. In addition Aua soils have more than 35 percent rock fragments in the control section.
GEOGRAPHIC SETTING: Fagasa soils are on very steep ridges and mountainsides. Slope is 30 to 130 percent. These soils formed in residuum of weathered basic igneous rock. Elevation is near sea level to 2,100 feet. The mean annual rainfall is 150 to
250 inches, and the mean annual temperature is 75 to 80 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Oloava and the competing Aua and Ofu soils. Oloava soils lack a paralithic contact within a depth of 40 inches and have cinders in the lower part of the control section.
DRAINAGE AND PERMEABILITY: Well drained; rapid or very rapid runoff; moderately rapid permeability.
USE AND VEGETATION: Most areas are in natural forest. Where slopes are least sloping, small patches are cleared and planted to taro and banana.
DISTRIBUTION AND EXTENT: Island of Tutuila. The soils of this series are of moderate extent, about 12,600 acres. MLRA 197.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: American Samoa, 1982.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - From the surface to 29 inches.
Paralithic contact - At a depth of 29 inches.
Taxonomic Version: Second edition Soil Taxonomy, 1999.
ADDITIONAL DATA: This pedon number S81-AQ603-021 was sampled and analysis was performed by the SCS National Soil Survey Lab in 1981.