LOCATION TAFUNA                  AS PB

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

TAFUNA SERIES

The Tafuna series consists of deep well-drained soils on uplands. These soils formed in surface accumulation of organic matter over fragmental Aa lava. Slope is 3 to 15 percent. Elevation is near sea level to 150 feet. The mean annual rainfall is about 150 inches, and the mean annual temperature is about 80 degrees F.

TAXONOMIC CLASS: Euic, isohyperthermic Typic Udifolists

TYPICAL PEDON: Tafuna extremely stony muck - on a 6 percent slope along a road. When described the soil was moist throughout. (Colors are for moist soil unless otherwise stated.)

Oa1--0 to 9 inches; black (10YR 2/1) extremely stony muck, black (10YR 2/1) dry; weak fine and very fine subangular blocky structure; very hard, firm, nonsticky and nonplastic; many roots; many pores; 20 percent stones, 30 percent cobbles, and 35 percent pebbles; slightly acid (pH 6.3); diffuse wavy boundary. (7 to 15 inches thick)

Oa2--9 to 18 inches; very dark grayish brown (10YR 3/2) and dark brown 10YR 3/3) extremely stony muck, dark yellowish brown (10YR 4/4) and brown (10YR 4/3) dry; strong fine and very fine granular structure; very hard, firm, nonsticky and nonplastic; many roots; many pores; 20 percent stones, 30 percent cobbles, and 35 percent pebbles; neutral (pH 6.6); diffuse wavy boundary. (8 to 15 inches thick)

2C--18 to 43 inches; fragmental Aa lava with little material from above horizon. (20 to 40 inches thick)

2R--43 inches; lava bedrock.

TYPE LOCATION: Tutuila Island, American Samoa; from the central part of Tafunafou 0.3 mile west on gravel road and 200 feet south of mechanic's shop; lat. 14 degrees 20 minutes 8 seconds S. and long. 170 degrees 44 minutes 6 seconds W.

RANGE IN CHARACTERISTICS: Depth to lava bedrock ranges from 40 to 60 inches. Hue of the O horizon is 7.5YR to 10YR. It is slightly acid to neutral.

COMPETING SERIES: These are the Kaimu, Malama, and Papai series. These soils have mean annual soil temperatures near 72 degrees F. Kaimu soils have an O horizon of peat. Malama soils are strongly acid and receive annual rainfall of 60 to 90 inches. Papai soils are moderately smeary.

GEOGRAPHIC SETTING: Tafuna soils are extremely stony and have irregular topography because of the underlying lava flow. They are on uplands. The general slopes are gentle to moderate. Slope is 3 to 15 percent. These soils formed in surface accumulation of organic matter over fragmental Aa lava. Elevation is near sea level to 150 feet. The mean annual rainfall is 120 to 175 inches, and the mean annual temperature is about 80 degrees F.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Iliili and Pavaiai soils. Iliili soils have mineral horizons about 9 inches thick. Pavaiai soils are loamy and moderately deep.

DRAINAGE AND PERMEABILITY: Well drained; very slow runoff; very rapid permeability.

USE AND VEGETATION: These soils are used for urban development and subsistence farming. Undisturbed areas are in tropical forest and support a number of large tree species.

DISTRIBUTION AND EXTENT: Islands of Tutuila and Ta`u. 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.

Taxonomic Version: Second edition Soil Taxonomy, 1999.

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National Cooperative Soil Survey
U.S.A.