LOCATION NAKWASINA               AK

Established Series
Rev.CSC/JMD/JPM
05/2022

NAKWASINA SERIES

The Nakwasina series consists of shallow, poorly drained soils formed in glacial till overlying paralithic material consisting of dense compact till. Nakwasina soils are on mountain and hill sideslopes. Slopes range from 5 to 55 percent. Mean annual precipitation is in excess of 60 inches and the mean annual temperature is about 46 degrees F.

TAXONOMIC CLASS: Loamy, mixed, superactive, nonacid, shallow Histic Cryaquepts

TYPICAL PEDON: Nakwasina muck - on a southeast facing broken slope of 15 percent at 620 feet elevation under forest vegetation. (All colors are for moist soil)

Oa -- 8 to 0 inches; muck; many very fine and fine roots; very strongly acid (pH 4.5); clear smooth boundary. (3 to 9 inches thick)

A -- 0 to 2 inches; very dark brown (7.5YR 2/2) silt loam; weak fine subangular blocky structure; friable; slightly sticky and slightly plastic; many very fine and fine roots; very strongly acid (pH 5.0); clear wavy boundary. (2 to 6 inches thick)

Bw -- 2 to 9 inches; dark brown (10YR 3/3) gravelly silt loam; weak fine subangular blocky structure; friable; slightly sticky and slightly plastic; common few faint very dark brown (10YR 2/2) mottles; 20 percent gravel; common very fine and fine roots; strongly acid (pH 5.5); clear smooth boundary. (2 to 14 inches thick)

C -- 9 to 14 inches; dark brown (10YR 3/3) very gravelly loam; massive; friable; slightly sticky and slightly plastic; many medium distinct dark grayish brown (2.5Y 4/2) mottles; 40 percent gravel; few very fine roots; moderately acid (pH 6.0); abrupt smooth boundary. (0 to 7 inches thick)

2Cd -- 14 to 60 inches; dark greenish gray (5GY 4/1) very gravelly loam; massive; very firm and brittle when moist; weakly cemented; common fine prominent dark brown (7.5YR 3/4) mottles; 40 percent gravel; slightly acid (pH 6.5).

TYPE LOCATION: False Island, Chatham Area, Alaska. SE 1/4, SW 1/4, Sec. 12, T.50S., R.64E., Copper River Meridian.

RANGE IN CHARACTERISTICS: MAST ranges from 38 to 42 degrees F. The thickness of the histic epipedon ranges from 8 to 16 inches. Thickness of the solum and depth to the paralithic contact of compact till ranges from 10 to 20 inches. Weighted average particle size of the control section has less than 18 percent clay and more than 15 percent fine sand or coarser. Coarse fragment content in the control section ranges from 0 to 50 percent gravel, weighted average is than 35 percent. Reactions increase with depth, ranging from extremely acid to slightly acid. An Oi horizon is present in some pedons.

The A horizon has hue from 5YR to 10YR, value of 2 to 3 and chroma of 1 or 2. Texture is commonly silt loam or mucky silt loam but ranges to include sandy loam or mucky sandy loam.

The Bw horizon has a hue from 2.5YR to 10YR, value from 2 to 4 and chroma of 2 or 3. Texture is commonly silt loam but ranges to include loam or sandy loam. Coarse fragment content ranges from 0 to 40 percent gravel. Mottles are commonly present. A mottled BC horizon is present in some pedons.

The C horizon has value from 3 to 5 and chroma from 2 to 4. Texture is commonly sandy loam or loam. Coarse fragment content ranges from 40 to 50 percent gravel. Mottles may be present.

The 2Cd horizon has hue from 2.5Y to 5GY, value from 3 to 5 and chroma of 1 or 2. Texture is commonly loam but ranges to include sandy clay loam or sandy loam. Coarse fragment content ranges from 35 to 75 percent gravel. Weak cementation is common. Bulk density is more than 1.8 grams per cubic centimeter and roots cannot penetrate.

COMPETING SERIES: This is the Slikok series in the same subgroup. Slikok soils have pH less than 5.5 (1:1,H2O) in the control section and do not have dense compact till within 40 inches.

GEOGRAPHIC SETTING: The Nakwasina soils are on mountain and hill sideslopes and till plains, and are formed in glacial till overlying compact till of mixed mineralogy. The climate is humid maritime with a mean annual precipitation range of 60 to 220 inches. The mean annual temperature is about 46 degrees F. and the mean summer temperature is about 57 degrees F. Elevation ranges from 0 to 1500 feet.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kina, Kushneahin and Yakobi soils on similar landforms. Kina and Kushneahin are very poorly drained organic soils. Yakobi soils are somewhat poorly drained and do not have a histic epipedon.

DRAINAGE AND PERMEABILITY: Poorly drained. Moderate permeability above the compact till, very slowly permeable in the compact till. Runoff is very slow.

USE AND VEGETATION: The Nakwasina soils are used for timber production, watershed protection, wildlife habitat and recreation. The overstory is dominantly yellow cedar with some mountain hemlock. The understory is dominantly blueberry with some crowberry, deer cabbage and sedge.

DISTRIBUTION AND EXTENT: Southeast Alaska. The series is extensive.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: WASILLA, ALASKA

SERIES ESTABLISHED: Chatham Area, Tongass National Forest, Alaska, 1992.

REMARKS: Diagnostic horizons and features recognized in this soil include: a histic epipedon from 8 to 0 inches; weighted average particle size of coarse-loamy from 0 to 14 inches; cryic temperature regime; pH greater than 5.5 (H2O,1:1) from 9 to 14 inches; paralithic material consisting of dense compact till at 14 inches.

ADDITIONAL DATA: Laboratory data is available for this soil: University of Idaho Number 83-AK-0363.

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National Cooperative Soil Survey
U.S.A.