LOCATION LEAFU                   AS PB

Established Series
RD: SN/PAB/BE/RG
01/2023

LEAFU SERIES

The Leafu series consists of deep, somewhat poorly drained soils on valley floors. These soils formed in fine-textured alluvium derived from weathered basic igneous rock. Slope is 0 to 3 percent. Elevation is near sea level to 250 feet. The mean annual rainfall is about 200 inches, and the mean annual temperature is about 79 degrees F.

TAXONOMIC CLASS: Fine, halloysitic, isohyperthermic Cumulic Hapludolls

TYPICAL PEDON: Leafu silty clay - on a 1 percent slope in a taro, banana, and coconut plantation. When described the soil was moist throughout. (Colors are for moist soil unless otherwise stated. Textures are apparent field textures.)

Ap1--0 to 4 inches; dark brown (7.5YR 3/2) silty clay loam, dark brown (7.5YR 3/2) dry; moderate fine and medium subangular blocky structure; very hard, firm, sticky and plastic; common roots; many very fine and few medium pores; at base of this horizon is a one-half inch layer of very fine sandy loam; moderately acid (pH 5.9); clear wavy boundary.

Ap2--4 to 13 inches; dark brown (7.5YR 3/3) silty clay, reddish brown (5YR 4/3) dry; weak fine and medium subangular blocky structure; very hard, firm, very sticky and very plastic; common roots; many very fine and few fine and medium pores; moderately acid (pH 5.9); clear smooth boundary. (Combined thickness of A horizons is 7 to 14 inches)

Bw1--13 to 19 inches; dark brown (7.5YR 3/2) very fine sandy loam, dark yellowish brown (10YR 4/4) dry; weak fine and medium subangular blocky structure; very hard, friable, slightly sticky and slightly plastic; common roots; many very fine pores; stratified layers of sand; slightly acid (pH 6.1); clear smooth boundary. (5 to 8 inches thick)

Bw2--19 to 36 inches; dark brown (7.5YR 3/3) silty clay, dark grayish brown (10YR 4/2) dry, common medium distinct strong brown (7.5YR 4/6) mottles; weak to moderate fine and medium subangular blocky structure; very hard, friable, very sticky and very plastic; common roots; many very fine and few medium pores; moderately acid (pH 6.0); clear smooth boundary. ( 8 to 18 inches thick).

Bw3--36 to 44 inches; very dark brown (10YR 2/2) silty clay, very dark brown (10YR 2/2) dry, common medium distinct strong brown (7.5YR 4/6) mottles; moderate fine and medium subangular blocky structure; very hard, firm, very sticky and very plastic; few roots; few very fine, few fine and medium pores; 5 percent pebbles; slightly acid (pH 6.1); clear smooth boundary. (7 to 31 inches thick)

BC--44 to 60 inches; dark brown (7.5YR 3/2) silty clay, brown (7.5YR 4/4) dry, common medium distinct strong brown (7.5YR 4/6) mottles; massive; extremely hard, firm, very sticky and very plastic; many very fine, fine, and few medium pores, moderately acid (pH 6.0).

TYPE LOCATION: Tutuila Island, American Samoa; at Leone 0.7 miles north of highway and 30 feet east of the valley road; lat. 14 degrees 20 minutes 14 seconds S. and long. 170 degrees 46 minutes 41 seconds W.

RANGE IN CHARACTERISTICS: The solum is 30 to 60 inches thick. The profile is 0 to 15 percent stones, 0 to 25 percent cobbles, and 0 to 25 percent pebbles. It is slightly acid to medium acid. A temporary water table is at depths of 3 to 5 feet.

The A horizon has hue of 5YR through 10YR, value of 3 to 4 dry, and chroma of 2 or 3 moist or dry. The fine earth fraction is silty clay loam or silty clay.

The B horizon has hue of 5YR through 10YR, value of 2 or 3 moist, 2 through 4 dry, and chroma of 2 or 3 moist, 2 through 4 dry. The fine earth fraction is commonly silty clay or clay. Thin lenses of coarser material are in some pedons.

The BC horizon has hue of 5YR through 10YR, value of 2 through 4 moist, 4 through 6 dry, and chroma of 2 through 4 moist or dry.

COMPETING SERIES: This is the Aua series in another family. Aua soils have greater than 35 percent rock fragments in the control section.

GEOGRAPHIC SETTING: Leafu soils are on nearly level valley floors. Slope is 0 to 3 percent. These soils formed in fine-textured alluvium derived from weathered basic igneous rock. Elevation is near sea level to 250 feet. The mean annual rainfall is 150 to 250 inches, and the mean annual temperature is about 79 degrees F.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Pavaiai and the competing Aua soils. Pavaiai soils are medial-skeletal and have a lithic contact at depths of 20 to 40 inches.

DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; moderately rapid permeability. The soils are flooded for short periods when streams overflow. A temporary water table is at depths of 3 to 5 feet.

USE AND VEGETATION: Leafu soils are used for subsistence farming and homesites. Taro, banana, breadfruit, and coconut are the main crops grown. Small areas are used for commercial vegetable farming and for pasture.

DISTRIBUTION AND EXTENT: Island of Tutuila. The soils of this series are of small extent, about 1000 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 60 inches.
Particle-size control section - From 10 to 40 inches.

Taxonomic Version: Second edition Soil Taxonomy, 1999.

ADDITIONAL DATA: Laboratory data are available on this pedon. Sample number S81AS 603-019 was sampled and analysis was performed by the National Soil Survey Lab in 1981.

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National Cooperative Soil Survey
U.S.A.