LOCATION PIKSRUN AK

Established Series
SWD/CBB
11/2024

PIKSRUN SERIES

Depth class: very deep
Drainage class: well drained
Parent material: gravelly loamy colluvium derived from sedimentary rock
Landscape: mountains
Landform: mountain slopes
Slopes: 10 to 55 percent
Mean annual precipitation: about 500 mm (20 in)
Mean annual air temperature: about -4 degrees C. (25 degrees F.)
Frost-free period: 70 to 90 days

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, acid, subgelic Typic Humigelepts

TYPICAL PEDON: Piksrun silt loam in a lichen and dwarf shrub community on a south facing convex, linear backslope on a slope of 15 percent at an elevation of 522 m (1713 ft)

Oe--0 to 7 cm (0 to 3 in); moderately decomposed plant material, very dark brown (10YR 2/2) moist, dark grayish brown (10YR 4/2) dry; many very fine and common fine roots throughout; very strongly acid (pH 4.6); abrupt smooth boundary. (2 to 10 cm, 1 to 4 in thick)

A--7 to 10 cm (3 to 4 in); silt loam, black (10YR 2/1) moist, dark gray (10YR 4/1) dry; weak fine subangular blocky structure; very friable, soft, nonsticky, nonplastic; nonsmeary; few fine roots throughout; very fine irregular pores; 5 percent gravel; very strongly acid (pH 4.9); abrupt smooth boundary. (1 to 35 cm, 0.5 to 14 in thick)

Bw--10 to 35 cm (4 to 14 in); gravelly silt loam, very dark grayish brown (10YR 3/2) moist, grayish brown (10YR 5/2) dry; weak medium subangular blocky structure; friable, slightly hard, nonsticky, nonplastic; nonsmeary; few very fine and fine roots throughout; very fine irregular pores; 25 percent gravel and 5 percent cobbles; strongly acid (pH 5.2); diffuse wavy boundary. (18 to 35 cm, 7 to 14 in thick)

C--35 to 200 cm (14 to 79 in); very gravelly silt loam, very dark grayish brown (2.5Y 3/2) moist, grayish brown (2.5Y 5/2) dry; massive; friable, slightly hard, nonsticky, nonplastic; nonsmeary; very fine irregular pores; 45 percent gravel and 10 percent cobbles; moderately acid (pH 5.6). (120 to 179 cm, 47 to 70 in thick)

TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 64 degrees 40 minutes 23.70 seconds north, longitude 159 degrees 51 minutes 58.96 seconds west, datum WGS84, UTM north 7172322.25 and UTM east 458647.17, zone 4W, datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: udic
Soil temperature regime: gelic
Mean annual soil temperature: -1 to 0 degrees C. (30 to 32 degrees F.)
Thickness of organic material: 2 to 10 cm (1 to 4 in)
Thickness of umbric epipedon: 21 to 80 cm (8 to 31 in)

Oe horizon:
Hue: 10YR or 7.5YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 2
Texture: moderately decomposed plant material
Organic matter: 60 to 90 percent
Reaction class: extremely acid to strongly acid (pH 3.5 to 5.5)

A horizon:
Hue: 10YR or 7.5YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 2
Texture: silt loam or its gravelly analogues
Sand: 10 to 48 percent
Silt: 50 to 80 percent
Clay: 2 to 10 percent
Rock fragments: 0 to 34 percent
Gravels: 0 to 34 percent
Organic matter: 2 to 8 percent
Reaction class: extremely acid to strongly acid (pH 3.5 to 5.4)

Bw horizon:
Hue: 10YR or 7.5YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 2 to 3
Texture: silt loam, loam or their gravelly analogues
Sand: 5 to 50 percent
Silt: 33 to 83 percent
Clay: 4 to 17 percent
Rock fragments: 15 to 50 percent
Gravels: 15 to 40 percent
Cobbles: 0 to 10 percent
Organic matter: 2 to 8 percent
Reaction class: very strongly acid to strongly acid (pH 4.5 to 5.4)

C horizon:
Hue: 2.5Y or 10YR
Value: 3 to 4 moist, 5 to 6 dry
Chroma: 2 to 3
Texture: silt loam or their gravelly or cobbly analogues
Sand: 5 to 47 percent
Silt: 50 to 83 percent
Clay: 3 to 15 percent
Rock fragments: 35 to 80 percent
Gravels: 20 to 75 percent
Cobbles: 5 to 60 percent
Organic matter: 0.4 to 3 percent
Reaction class: very strongly acid to moderately acid (pH 4.5 to 6.0)

COMPETING SERIES: This is the Apkun (AK) series.
Apkun soils have a lithic contact at depths between 45 to 129 cm (18 to 51 in), a lithologic discontinuity at depths between 35 and 84 cm (14 to 33 in), and occur on similar landforms on backslope positions.

GEOGRAPHIC SETTING:
Elevation: 250 to 630 meters (820 to 2065 feet)
Parent material: gravelly loamy colluvium derived from sedimentary rock
Landform: mountain slopes
Slopes: 10 to 55 percent
Mean annual precipitation: 400 to 500 mm (16 to 20 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 Apkun, Nunanjiak, Myoukchuk, and Niakuk soils.
Apkun soils have a lithic contact at depths between 45 to 129 cm (18 to 51 in) and occur on similar landforms on backslope positions.
Nunanjiak soils have a folistic epipedon at depths between 0 to 21 cm (0 to 8 in), volcanic glass at depths between 21 to 110 cm (8 to 43 in), and occur on similar landforms on backslope positions.
Myoukchuk soils have an ochric epipedon, paralithic contact at depths between 84 to 146 cm (33 to 57 in), and occur on similar landforms on backslope positions.
Niakuk soils have an ochric epipedon, a cambic horizon at depths between 5 to 73 cm (2 to 29 in), 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 horizon, moderately high in the A and C horizons, and moderately high to high in the Bw horizon
Permeability: rapid to very rapid in the Oe horizon, moderate in the A and C horizons, and moderate to moderately rapid in the Bw horizon
Runoff: medium to high

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: reindeer lichen, greygreen reindeer lichen, black crowberry, marsh Labrador tea, bog blueberry, Flavocetraria culcullata, splendid feather moss, Schreber's big red stem moss, cetraria lichen, dwarf birch, cup lichen, Bigelow's sedge, arctic sweet coltsfoot, tealeaf willow, and white spruce.

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: 32 to 107 cm (13 to 42 in)

Umbric epipedon: 7 to 35 cm (3 to 14 in) (A and Bw horizons)

Hemic soil materials: 0 to 7 cm (0 to 3 in) (Oe horizon)

ADDITIONAL DATA:

User pedon ID: 2021AK290843

National Cooperative Soil Survey
U.S.A.