LOCATION ALAKAI                  HI

Established Series
Rev. CWS/SN/HI/MRK/JVP
03/2017

ALAKAI SERIES

The Alakai series consists of deep, very poorly drained soils that formed in organic material overlaying clay weathered from basalt. Alakai soils are in swamps located on high mountains. Slopes range from 0 to 30 percent. The mean annual rainfall is about 7,112 millimeters (280 inches), and the mean annual temperature is about 13 degrees C. (56 degrees F.)

TAXONOMIC CLASS: Clayey, ferrihumic, dysic, isomesic Terric Haplosaprists

TYPICAL PEDON: Alakai mucky peat--rain forest. (Colors are for moist soil unless otherwise noted. All textures are apparent field textures.)

Oe--0 to 20 centimeters (0 to 8 inches); very dusky red (10R 2/2) mucky peat, reddish black (10R 2/1) dry; massive; extremely hard, firm, moderately smeary, slightly sticky and slightly plastic; many roots; ultra acid (pH 3.4); clear smooth boundary. (18 to 31 centimeters {7 to 12 inches} thick)

Oa1--20 to 31 centimeters (8 to 14 inches); reddish black (10R 2/1) muck, reddish black (10R 2/1) dry; massive; extremely hard, firm, slightly sticky and slightly plastic, moderately smeary; many roots; ultra acid (pH 3.4); clear smooth boundary. (10 to 23 centimeters {4 to 9 inches} thick)

Oa2--31 to 56 centimeters (14 to 22 inches); dark reddish brown (2.5YR 2/4) muck, reddish black (10R 2/1) dry; massive; extremely hard, friable, slightly sticky and slightly plastic, moderately smeary; many roots; ultra acid (pH 3.4); clear smooth boundary. (15 to 25 centimeters {6 to 10 inches} thick)

Oa3--56 to 81 centimeters (22 to 32 inches); very dusky red (2.5YR 2/2) muck, black (N 2/) dry; massive; extremely hard, friable, slightly sticky and slightly plastic, moderately smeary; many roots; ultra acid (pH 3.4); abrupt smooth boundary. (15 to 25 centimeters {6 to 10 inches} thick)

2Cg1--81 to 97 centimeters (32 to 38 inches); gray (5Y 5/1), brown (7.5YR 5/4), and reddish yellow (7.5YR 6/8) clay, rubbed dry color grayish brown (2.5Y 5/2) and gray (2.5Y 6/1); 1 to 2 inches of ironstone gravel at top; massive; very hard, firm, very sticky and very plastic; few very fine roots; common very fine pores; extremely acid (pH 4.0); clear smooth boundary. (10 to 20 centimeters {4 to 8 inches} thick)

2Cg2--97 to 130 centimeters (38 to 51 inches); gray (5Y 5/1), some grayish brown (2.5Y 5/2) clay, gray (5Y 6/1), and light gray (5Y 7/1) dry; massive; very hard, firm, very sticky and very plastic; few very fine roots; common very fine pores; 4 percent irregular pebbles, l/2 to 2 inches across; extremely acid (pH 4.0).

TYPE LOCATION: Kauai County, Hawaii; Haena Quadrangle; lat. 22 degrees 09 minutes 13.642 seconds N. and long. 159 degrees 35 minutes 37.94 seconds W. (WGS84).

RANGE IN CHARACTERISTICS:
Mean annual soil temperature is about 14 degrees C. (57 degrees F.) Depth to clay ranges from 46 to 91 centimeters (18 inches to 36 inches). In places, the clay rests on an ironstone sheet that ranges in thickness of 0.3 to 10 centimeters (1/8 inch to 4 inches). Saprolite is at depths of 91 to more than 152 centimeters (36 to more than 60 inches) below the surface.

The 2C horizon
Color: brown (10YR 5/3), gray (10YR 5/l; N 6/; 5Y 5/1) or greenish gray (5GY 6/1), and it has mottles of brown (7.5YR 5/4) and reddish yellow (7.5YR 6/8), in some places.

COMPETING SERIES: There are no known competing series in Hawaii.

GEOGRAPHIC SETTING: Alakai soils are on slopes of mountain ridges and in some depressions. Slope is 0 to 30 percent. Elevation ranges from 914 to 1,524 meters (3,000 to 5,000 feet). Alakai soils formed in organic material overlying residuum from basalt. Average annual rainfall ranges from 2,540 to 11,430 millimeters (100 to 450 inches). Clouds and fog cover the landscape nearly every day. Average January temperature is about 12 degrees C. (54 degrees F.), average July temperature is about 14 degrees C. (58 degrees F.), and average annual temperature is about 13 degrees C. (56 degrees F.)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hulua, Kunuweia, and Waialeale soils. Hulua and Kunuweia soils are mineral soils containing ironstone pebbles. Waialeale soils are on steeper slopes and have organic surface layers less than 71 centimeters (28 inches) thick.

DRAINAGE AND PERMEABILITY: Very poorly drained; slow runoff; slow to moderately slow permeability below the muck.

USE AND VEGETATION: Used for wildlife, watershed, and recreation. Vegetation is ohia lehua (Metrosideros polymorpha), lapalapa (Cheirondendron sp.), Hawaiian lobelia (Lobelia hypoleuca), mokihana
(Pelea anista), pukiawe (Styphelia tameiameiae), treefern (Cibotium splendens), bracken fern (Pteridium aquilinum), uki uki (Dianella), and associated plants.

DISTRIBUTION AND EXTENT: Kauai and Honolulu Counties, Hawaii. The series is of small extent, comprising about 6,700 acres.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Soil Survey, Territory of Hawaii, 1949.

REMARKS:
FCC Classification: Oag+k (based on Amalu S94HI-000-001).

Edit Log: 12/03 SN. Horizon designations updated; added FCC.
8/00 SN. Classification changed from Clayey, kaolinitic, dysic, isomesic Terric Troposaprists due to changes in Taxonomy.
7/2014 MK. Horizon depths updated and other minor edits; type location converted to WGS84.

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National Cooperative Soil Survey
U.S.A.