LOCATION APUN                    AK

Established Series
Rev. MPS/SAS
10/2024

APUN SERIES

Depth class: shallow to permafrost
Drainage class: poorly drained
Parent material: mossy organic material over grassy organic material over cryoturbate over loess
Landscape: mountains, hills, river valleys
Landform: mountain slopes, hillslopes, terraces
Slope: 4 to 20 percent
Mean annual precipitation: about 350 mm (13.8 inches)
Mean annual air temperature: about -3 degrees C (27 degrees F)
Frost-free period: 55 to 90 days

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, nonacid, subgelic Typic Histoturbels

TYPICAL PEDON: Apun peat in a tussock-scrub community on a north by northwest facing convex, concave footslope of a hill on a slope of 8 percent at an elevation of 276 m (906 ft).

Oi--0 to 15 cm (0 to 6 in); peat; dark yellowish brown (10YR 3/4) moist, yellowish brown (10YR 5/4) dry, common very fine, many fine and medium roots throughout; strongly acid (pH 5.4); clear smooth boundary. (10 to 20 cm, 4 to 8 in thick)

Oe--15 to 38 cm (6 to 15 in); mucky peat; very dark brown (7.5YR 2.5/2) moist, brown (7.5YR 4/2) dry, common very fine and fine roots throughout; strongly acid (pH 5.1); clear smooth boundary. (5 to 30 cm, 2 to 12 in thick)

Ajj--38 to 42 cm (15 to 17 in); silt loam, brown (7.5YR 5/2) dry, very dark brown (7.5YR 2.5/2) moist; weak, coarse, granular structure; friable, nonsticky, nonplastic; common very fine roots throughout; common fine irregular pores throughout; strongly acid (pH 5.3); abrupt irregular boundary. (5 to 35 cm, 2 to 14 in thick)

Cgf--42 to 150 cm (17 to 60 in); permanently frozen silt loam, light brownish gray (10YR 6/2) dry, dark grayish brown (10YR 4/2) moist; massive; very firm, slightly sticky, nonplastic; common very fine slightly acid (pH 6.1). 2-inch ice lens at top of Cf, thin ice lenses throughout horizon. (68 to 125 cm, 27 to 49 in thick)

TYPE LOCATION: Nulato Hills Area, Alaska, latitude 63.4516510 degrees, longitude -160.9589380 degrees, datum WGS84, UTM north 7037406 and UTM east 402322, zone 4, datum WGS84.

RANGE IN CHARACTERISTICS:
Soil moisture regime: aquic
Soil temperature regime: gelic
Mean annual soil temperature: -1 to 0 degrees C. (30 to 32 degrees F.)
Thickness of histic epipedon: 20 to 40 cm
Thickness of reduced matrix: 68 to 125 cm (27 to 49 in)
Thickness of cryoturbation: 5 to 35 cm (2 to 14 in)
Depth to permafrost contact: 15 to 70 cm (6 to 28 in)

Oi and Oe horizon:
Hue: 7.5YR or 10YR
Value: 2.5 or 3 moist, 4 or 5 dry
Chroma: 2 to 4
Texture: peat or mucky peat
Organic matter: 60 to 90 percent
Reaction class: extremely acid to moderately acid (pH 3.5 to 6.0)

Ajj horizon
Hue:7.5YR or 10YR
Value:2.5 to 4 moist, 3 to 6 dry
Chroma:1 to 3
Fine-earth texture: mucky silt, mucky silt loam, silt loam
Sand: 8 to 45 percent
Clay: 5 to 15 percent
Silt: 40 to 87 percent
Organic carbon: 5 to 15 percent
Rock fragments: 0 to 15 percent gravels or channers
Reaction class: very strongly to moderately acid (pH 4.8 to 5.7)

Cgf horizon
Hue: 2.5Y or 10YR
Value: 3 to 5 moist, 5 to 7 dry
Chroma: 1 to 2
Texture: permanently frozen silt loam, permanently frozen loam
Sand: 12 to 50 percent
Clay: 5 to 18 percent
Silt: 32 to 83 percent
Organic carbon: 2 to 5 percent
Rock fragments: 0 to 25 percent gravels or channers
Reaction: strongly acid to slightly acid (pH 5.5 to 6.5)

COMPETING SERIES: These are the Tanacross and Tulebagh (AK) series
Tanacross soils lack coarse fragments and have visible mica
Tulebagh soils lack coarse fragments, have cryoturbated organic material throughout pedon, and have pH ranging up to 8.5

GEOGRAPHIC SETTING:
Elevation: 10 to 550 m (33 to 1804 feet)
Parent material: mossy organic material over grassy organic material over cryoturbate over loess
Landscape: mountains, hills and river valleys
Landform: mountain slopes, hillslopes and terraces
Slope: 4 to 20 percent
Mean annual precipitation: 350 to 600 mm (13.8 to 19.7 in)
Mean annual air temperature: -5 to -1 degrees C. (23 to 30 degrees F.)
Frost-free period: 55 to 90 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Willowcreek and the Nikaat soils.
Willowcreek soils have an ochric epipedon, lack permafrost, lack gelic soil material, and occur in drainageways
Nikaat soils have cryoturbation throughout the profile, have a layer containing volcanic glass, occur on slopes of 0 to 5 percent, and occur on plains and toeslopes of hills

DRAINAGE AND PERMEABILITY:
Drainage class: poorly drained
Saturated hydraulic conductivity: moderately high or high in the Oi and Oe horizons, very low in the Ajj and Cgf horizons
Permeability: moderate to moderately rapid in the Oi and Oe horizons, very slow in the Ajj and Cgf horizons

USE AND VEGETATION:
Use: wildlife habitat, recreation, subsistence
Native vegetation: sphagnum moss, marsh Labrador tea, tussock cottongrass, Schreber's big red stem moss, Bigelow's sedge, splendid feather moss, dwarf birch

DISTRIBUTION AND EXTENT: MLRA 240, Nulato Hills-Southern Seward Peninsula Highlands, Alaska; MLRA 240. This series is of large extent

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

SERIES ESTABLISHED: Nulato Hills Area, Alaska, Nome Census Area, Alaska; 2021

REMARKS: Diagnostic horizons and features recognized in this profile include:
Particle-size control section: 63 to 138 cm

Histic epipedon: 0 to 38 cm (0 to 15 in) (Oi and Oe horizons)

Cryoturbation: 38 to 42 cm (15 to 17 in) (Ajj horizon)

Permafrost: 42 to 150 cm (17 to 59 in) (Cgf horizon)

Gelic materials: 42 to 150 cm (17 to 59 in) (Cgf horizon)

Aquic conditions: 0 to 150 cm (0 to 59 in) (Oi, Oe, Ajj, and Cgf horizons)

Reduced matrix: 42 to 150 cm (17 to 59 in) (Cgf horizon)

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National Cooperative Soil Survey
U.S.A.