LOCATION NIAKUK AK

Tentative Series
BMC/CBB
10/2024

NIAKUK SERIES

Depth class: deep to bedrock, lithic
Drainage class: well drained
Parent material: loamy colluvium over gravelly colluvium over residuum weathered from mudstone
Landscape: mountains
Landform: mountain slopes
Slopes: 15 to 55 percent
Mean annual precipitation: about 500 mm (19.68 in)
Mean annual air temperature: about -4 degrees C. (25 degrees F.)
Frost-free period: 70 to 90 days

TAXONOMIC CLASS: Coarse-loamy over fragmental, mixed, superactive Typic Dystrocryepts

TYPICAL PEDON: Niakuk loam in a dwarf birch community on a southeast facing linear, convex shoulder on a slope of 34 percent at an elevation of 393 m (1290 ft)

Oe--0 to 4 cm (0 to 2 in); moderately decomposed plant material, very dark brown (7.5YR 2.5/2) broken face moist, brown (7.5YR 4/2) dry; common very fine, fine, medium, and coarse roots throughout; extremely acid (pH 4.0); clear wavy boundary (2 to 12 cm, 1 to 5 in thick)

A--4 to 12 cm (2 to 5 in); loam, dark yellowish brown (10YR 4/4) broken face moist, light yellowish brown (10YR 6/4) dry; weak fine granular structure; very friable, soft, nonsticky, nonplastic; nonsmeary; common very fine, fine, medium, and coarse roots throughout; very fine and fine irregular pores; 5 percent gravel; very strongly acid (pH 4.7); clear irregular boundary (3 to 10 cm, 1 to 4 in thick)

Bw1--12 to 24 cm (5 to 9 in); silt loam, yellowish brown (10YR 5/6) broken face moist, yellow (10YR 7/6) dry; weak fine subangular blocky structure; very friable, soft, nonsticky, nonplastic; strongly smeary; common very fine roots throughout; very fine and fine irregular pores; 8 percent gravel; strongly acid (pH 5.3); abrupt irregular boundary. (5 to 16 cm, 2 to 6 in thick)

Bw2--24 to 56 cm (9 to 22 in); loam, dark gray (10YR 4/1) broken face moist, gray (10YR 6/1) dry; weak fine subangular blocky structure; very friable, soft, nonsticky, nonplastic; nonsmeary; common very fine roots throughout; very fine and fine irregular pores; 10 percent gravel; strongly acid (pH 5.3); gradual smooth boundary (10 to 35 cm, 4 to 14 in thick)

2C1--56 to 75 cm (22 to 30 in); gravel; coarse and very coarse interstitial pores; 85 percent gravel and 10 percent cobbles; clear wavy boundary. (10 to 25 cm, 4 to 10 in thick)

2C2--75 to 120 cm (30 to 47 in); gravel; coarse and very coarse interstitial pores; 60 percent gravel and 35 percent cobbles. (40 to 52 cm, 16 to 20 in thick)

3R--120 to 145 cm (47 to 57 in); strongly coherent to indurated mudstone bedrock. (25 cm, 10 in thick)

TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 64 degrees 19 minutes 12.70 seconds north, longitude 159 degrees 52 minutes 40.30 seconds west, datum WGS84, UTM north 7132988.11 and UTM east 457554.98, zone 4W, datum WGS84

RANGE IN CHARACTERISTICS:

Soil moisture regime: udic
Soil temperature regime: cryic
Mean annual soil temperature: 0 to -3 degrees C. (32 to 27 degrees F.)
Thickness of organic material: 2 to 12 cm (1 to 5 in)
Thickness of ochric epipedon: 5 to 22 cm (2 to 9 in)
Thickness of cambic horizon: 15 to 44 cm (6 to 17 in)
Depth to lithologic discontinuity: 20 to 73 cm (8 to 29 in) and 70 to 150 cm (28 to 59 in)
Depth to lithic contact: 100 to 150 cm (40 to 60 in)

Oe horizon:
Hue: 7.5YR or 5YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 3
Texture: moderately decomposed plant material
Organic matter: 60 to 90 percent
Reaction class: ultra acid to very strongly acid (pH 3.0 to 5.0)

A horizon:
Hue: 10YR or 7.5YR
Value: 2 to 4 moist, 4 to 6 dry
Chroma: 1 to 4
Texture: loam, silt loam, or silt
Sand: 10 to 45 percent
Silt: 40 to 86 percent
Clay: 4 to 16 percent
Rock fragments: 0 to 14 percent
Gravels: 0 to 14 percent
Organic matter: 2 to 8 percent
Reaction class: extremely acid to very strongly acid (pH 3.5 to 5.0)

Bw horizons:
Hue: 10YR or 2.5Y
Value: 3 to 5 moist, 5 to 7 dry
Chroma: 1 to 6
Texture: silt loam, loam, or their gravelly analogues
Sand: 20 to 52 percent
Silt: 33 to 73 percent
Clay: 7 to 15 percent
Rock fragments: 0 to 34 percent
Gravels: 0 to 34 percent
Organic matter: 1.0 to 3.0 percent
Reaction class: very strongly acid to strongly acid (pH 4.5 to 5.5)

2C horizons:
Texture: gravel
Rock fragments: 90 to 100 percent
Gravels: 50 to 100 percent
Cobbles: 0 to 45 percent

3R horizon
Strongly coherent to indurated mudstone bedrock.

Some pedons have a lithic contact at moderately deep depths.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING:
Elevation: 300 to 700 meters (985 to 2295 feet)
Parent material: loamy colluvium over gravelly colluvium over residuum weathered from mudstone
Landform: mountain slopes
Slopes: 15 to 55 percent
Mean annual precipitation: 400 to 600 mm (16 to 24 in)
Mean annual air temperature: -6 to -1 degrees C. (21 to 30 degrees F.)
Frost free period: 70 to 90 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aullasik, Nunanjiak, Anugi, Urgiilik, Imnak, Apkun, and Myoukchuk soils.
* Aullasik soils have an umbric epipedon at depths between 6 to 41 cm (2 to 16 in) and occur on similar landforms on backslope positions.
* Nunanjiak soils have folistic and umbric epipedons at depths between 0 to 67 (0 to 26 in), volcanic glass at depths between 21 to 110 cm (8 to 43 in), and occur on similar landforms on backslope positions.
*Anugi soils have a strongly to slightly acid reaction class in the cambic horizon between 7 to 76 cm (3 to 30 in) and occur on similar landforms on backslope positions.
*Urgiilik soils have lithic contact at depths between 35 to 126 cm (14 to 50 in) and occur on similar landforms on backslope positions.
* Imnak soils have a mollic epipedon, extremely channery textures at depths between 2 to 49 cm (1 to 19 in), and occur on similar landforms on backslope positions.
* Apkun soils have an umbric epipedon at depths between 4 to 43 cm (2 to 17 in) and occur on similar landforms on backslope positions.
* Myoukchuk soils do not have a cambic horizon and occur on similar landforms on backslope positions.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: well drained
Saturated Hydraulic Conductivity: very high in the Oe and 2C horizons, moderately high to high in the A and Bw2 horizons, and moderately high in the Bw1 horizon
Permeability: rapid to very rapid in the Oe horizon, moderate to moderately rapid in the A and Bw2 horizons, moderate in the Bw1 horizon, and very rapid in the 2C horizons
Runoff: high

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: dwarf birch, marsh Labrador tea, snow lichen, reindeer lichen, greygreen reindeer lichen, black crowberry, bog blueberry, lingonberry, white spruce, shortstalk sedge, and alpine azalea.

DISTRIBUTION AND EXTENT: MLRA 240, Nulato Hills-Southern Seward Peninsula Highlands. The series is of moderate extent.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Wasilla, Alaska

SERIES ESTABLISHED: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey, Alaska, 2024.

REMARKS: Diagnostic features and horizons recognized in this profile include:

Particle-size control section: 29 to 104 cm (11 to 41 in)

Ochric epipedon: 0 to 12 cm (0 to 5 in) (Oe and A horizons)

Cambic horizon: 12 to 56 cm (5 to 22 in) (Bw horizons)

Lithologic discontinuity: 56 to 120 cm (22 to 47 in) and 120 to 145 cm (47 to 57 in) (2C1, 2C2, and 3R horizons)

Lithic contact: 125 cm (49 in) (3R horizon)

ADDITIONAL DATA:

User pedon ID: 2021AK290667

National Cooperative Soil Survey
U.S.A.