LOCATION ULUUN                   AK

Tentative Series
SAS/CBB
10/2024

ULUUN SERIES

Depth class: very deep
Drainage class: somewhat poorly drained
Parent material: organic material over loamy slope alluvium derived from limestone and sandstone
Landscape: hills
Landform: hillslopes
Slopes: 3 to 15 percent
Mean annual precipitation: about 400 mm (16 in)
Mean annual air temperature: about -4 degrees C. (25 degrees F.)
Frost-free period: 70 to 85 days

TAXONOMIC CLASS: Fine-loamy, mixed, active Fluvaquentic Haplocryepts

TYPICAL PEDON: Uluun silt in a white spruce forest on a south facing linear, convex backslope on a slope of 6 percent at an elevation of 215 m (705 ft)

Oe--0 to 12 cm (0 to 5 in); moderately decomposed plant material, very dark brown (7.5YR 2.5/2) broken face moist, weak red (7.5R 4/2) broken face dry; many very fine, fine, and medium roots throughout; neutral (pH 6.7); clear smooth boundary (9 to 15 cm, 4 to 6 in thick)

Oa--12 to 21 cm (5 to 8 in); highly decomposed plant material, black (7.5YR 2.5/1) broken face moist, dark reddish gray (7.5R 4/1) broken face dry; many very fine and common fine roots throughout; slightly acid (pH 6.3); abrupt smooth boundary (6 to 12 cm, 2 to 5 in thick)

A--21 to 28 cm (8 to 11 in); silt, very dark gray (7.5YR 3/1) broken face moist, reddish gray (7.5R 5/1) broken face dry; weak medium granular structure; friable, slightly hard, nonsticky, nonplastic; nonsmeary; many very fine and common fine roots throughout; very fine dendritic tubular pores; 10 percent coarse, faint, irregular, noncoherent, cemented dark reddish brown (5YR 2.5/2) masses of oxidized iron with clear boundaries on surfaces along root channels; noneffervescent; moderately acid (pH 5.6); abrupt smooth boundary (4 to 15 cm, 2 to 6 in thick)

Bg--28 to 41 cm (11 to 16 in); loam, gray (5Y 5/1) broken face moist, light gray (5Y 7/1) broken face dry; weak thick lenticular structure; very friable, soft, slightly sticky, slightly plastic; nonsmeary; common very fine and few fine roots throughout; very fine vesicular and fine dendritic tubular pores; 1 percent prominent silt coats on surfaces along root channels; 10 percent medium, prominent, irregular, noncoherent, cemented dark yellowish brown (10YR 4/6) masses of oxidized iron with clear boundaries in matrix; noneffervescent; moderately acid (pH 5.7); clear irregular boundary (5 to 15 cm, 2 to 6 in thick)

Bt1--41 to 51 cm (16 to 20 in); loam, olive brown (2.5Y 4/3) broken face moist, light yellowish brown (2.5Y 6/3) broken face dry; 2 percent medium, distinct, irregular grayish brown (2.5Y 5/2) mottles; strong medium lenticular parts to strong medium granular structure; firm, moderately hard, moderately sticky, moderately plastic; nonsmeary; common very fine and few fine roots throughout; very fine vesicular and fine dendritic tubular pores; 30 percent prominent clay films on all faces of peds; 20 percent medium, prominent, irregular, noncoherent, cemented dark yellowish brown (10YR 4/6), moist, masses of oxidized iron with clear boundaries in matrix; noneffervescent; slightly acid (pH 6.3); clear irregular boundary (6 to 15 cm, 2 to 6 in thick)

Bt2--51 to 60 cm (20 to 24 in); loam, olive brown (2.5Y 4/3) broken face moist, light yellowish brown (2.5Y 6/3) broken face dry; strong fine angular blocky structure; friable, slightly hard, moderately sticky, moderately plastic; nonsmeary; few very fine roots throughout; very fine vesicular pores; 1 percent prominent clay films on surfaces along pores; noneffervescent; neutral (pH 6.6); clear smooth boundary (5 to 12 cm, 2 to 5 in thick)

ABkb--60 to 67 cm (24 to 26 in); sandy loam, very dark grayish brown (2.5Y 3/2) broken face moist, grayish brown (2.5Y 5/2) broken face dry; weak coarse granular structure; friable, slightly hard, nonsticky, nonplastic; nonsmeary; few very fine roots throughout; very fine irregular pores; slight effervescence; neutral (pH 6.7); clear smooth boundary (3 to 8 cm, 1 to 3 in thick)

Bt3--67 to 78 cm (26 to 31 in); channery loam, dark olive brown (2.5Y 3/3) broken face moist, light olive brown (2.5Y 5/3) broken face dry; strong medium lenticular parts to strong medium granular structure; friable, slightly hard, moderately sticky, moderately plastic; nonsmeary; common very fine and fine roots throughout; very fine tubular and very fine dendritic tubular pores; 20 percent gravel; noneffervescent; neutral (pH 6.8); clear smooth boundary (6 to 12 cm, 2 to 5 in thick)

BC--78 to 105 cm (31 to 41 in); channery sandy clay loam, dark olive brown (2.5Y 3/3) broken face moist, light olive brown (2.5Y 5/3) broken face dry; strong very fine granular structure; friable, slightly hard, moderately sticky, very plastic; nonsmeary; common very fine and fine roots throughout; very fine dendritic tubular pores; 1 percent prominent silt coats on all faces of peds; 5 percent medium, prominent, irregular, noncoherent, cemented strong brown (7.5YR 4/6) masses of oxidized iron with clear boundaries around rock fragments; 30 percent gravel; noneffervescent; neutral (pH 7.1); clear smooth boundary (20 to 40 cm, 8 to 16 in thick)

Ck--105 to 200 cm (41 to 79 in); clay loam, dark grayish brown (2.5Y 4/2) broken face moist, light brownish gray (2.5Y 6/2) broken face dry; massive; firm, moderately hard, moderately sticky, very plastic; nonsmeary; common very fine and few fine roots throughout; very fine dendritic tubular pores; 70 percent prominent clay films on all faces of peds; strong effervescence; neutral (pH 6.6). (56 to 136 cm, 22 to 54 in thick)

TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 65 degrees 13 minutes 20.92 seconds north, longitude 160 degrees 24 minutes 24.25 seconds west, datum WGS84, UTM north 7233982.92 and UTM east 434219.60, zone 4W, datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: udic
Soil temperature regime: cryic
Mean annual soil temperature: -0.5 to 2.5 degrees C. (31 to 36 degrees F.)
Thickness of organic material: 15 to 27 cm (6 to 11 in)
Thickness of folistic epipedon: 15 to 27 cm (6 to 11 in)
Thickness of cambic horizon: 15 to 144 cm (6 to 57 in)
Depth to redoximorphic concentrations: 64 to 144 cm (25 to 57 in)
Depth to free carbonates: 6 to 144 cm (2 to 57 in)
Depth to aquic conditions: 25 to 50 cm (10 to 20 in)

O horizons:
Hue: 7.5YR, 5YR, or 10YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 2
Texture: moderately or highly decomposed plant material
Organic matter: 60 to 90 percent
Reaction class: strongly acid to neutral (pH 5.1 to 7.3)

A horizon:
Hue: 7.5YR or 10YR
Value: 2 to 4 moist, 4 to 6 dry
Chroma: 1 to 2
Texture: silt or silt loam
Sand: 5 to 32 percent
Silt: 54 to 92 percent
Clay: 3 to 14 percent
Organic matter: 2 to 6 percent
Reaction class: strongly acid to moderately acid (pH 5.1 to 6.0)

Bg horizon:
Hue: 5Y or 2.5Y
Value: 4 to 5 moist, 6 to 7 dry
Chroma: 1 to 2
Texture: loam
Sand: 30 to 50 percent
Silt: 28 to 50 percent
Clay: 16 to 24 percent
Organic matter: 0.5 to 2 percent
Reaction class: strongly acid to slightly acid (pH 5.1 to 6.5)

Bt1 and Bt2 horizons:
Hue: 2.5Y or 5Y
Value: 4 to 5 moist, 6 to 7 dry
Chroma: 1 to 3
Texture: loam or sandy clay loam
Sand: 25 to 65 percent
Silt: 7 to 50 percent
Clay: 18 to 28 percent
Organic matter: 0.5 to 2 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)

ABkb horizon:
Hue: 2.5Y, 10YR, or 7.5YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 4
Texture: sandy loam or loam
Sand: 25 to 70 percent
Silt: 7 to 50 percent
Clay: 12 to 25 percent
Organic matter: 1 to 3 percent
Reaction class: slightly acid to slightly alkaline (pH 6.1 to 7.8)

Bt3 horizon:
Hue: 2.5Y or 5Y
Value: 3 to 5 moist, 5 to 7 dry
Chroma:1 to 3
Texture: loam, sandy clay loam or their channery analogues
Sand: 25 to 75 percent
Silt: 10 to 50 percent
Clay: 18 to 28 percent
Rock fragments: 0 to 25 percent
Channers: 0 to 25 percent
Organic matter: 0.5 to 2 percent
Reaction class: slightly acid to neutral (pH 6.1 to 7.3)

BC horizon:
Hue: 2.5Y or 5Y
Value: 3 to 5 moist, 5 to 7 dry
Chroma: 1 to 3
Texture: sandy clay loam or its channery analogues
Sand: 45 to 70 percent
Silt: 0 to 28 percent
Clay: 22 to 32 percent
Rock fragments: 0 to 34 percent
Channers: 0 to 34 percent
Organic matter: 0.5 to 2 percent
Reaction class: slightly acid to neutral (pH 6.1 to 7.3)

Ck horizon:
Hue: 2.5Y or 5Y
Value: 4 to 5 moist, 6 to 7 dry
Chroma: 2 to 3
Texture: clay loam
Sand: 20 to 45 percent
Silt: 21 to 53 percent
Clay: 27 to 34 percent
Organic matter: 0.4 to 2 percent
Reaction class: slightly acid to slightly alkaline (pH 6.1 to 7.8)

Some pedons have cryoturbated horizons

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING:
Elevation: 50 to 380 meters (160 to 1250 feet)
Parent material: organic material over loamy slope alluvium derived from limestone and sandstone
Landform: hillslopes
Slopes: 3 to 15 percent
Mean annual precipitation: 300 to 500 mm (12 to 20 in)
Mean annual air temperature: -6 to -2 degrees C. (21 to 28 degrees F.)
Frost free period: 70 to 85 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Amigak and Muskox soils.
Amigak soils have a histic epipedon, do not have free carbonates anywhere in the profile, and occur on similar landforms on backslope and footslope positions.
Muskox soils have an umbric epipedon, do not have free carbonates anywhere in the profile, and occur on similar landforms on backslope positions.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: somewhat poorly drained
Saturated Hydraulic Conductivity: very high in the O horizons, moderately high in the A, BC, and Ck horizons, and moderately high to high in the Bg, Bt, an ABkb horizons
Permeability: rapid to very rapid in the O horizons, moderate in the A horizon, moderate to moderately rapid in the Bg horizon, slow to moderately rapid in the Bt horizons, moderate to rapid in the ABkb horizon, and slow to moderate in the Ck horizon
Runoff: very high

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation : white spruce, Schreber's big red stem moss, splendid feather moss, Richardson's willow, bog blueberry, white arctic mountain heather, black crowberry, halberd willow, Dasiphora fruticosa, resin birch, grayleaf willow, moss, reindeer lichen, tomentypnum moss, netleaf willow, tealeaf willow, entireleaf mountain-avens, lingonberry, aulacomnium moss, greygreen reindeer lichen, bog rosemary, Scouler's willow, northern singlespike sedge, red fruit bearberry, narrowleaf saw-wort, abietinella moss, felt lichen, western arctic shootingstar, field horsetail, and sheathed sedge.

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: 46 to 121 cm (18 to 48 in)

Folistic epipedon: 0 to 21 cm (0 to 8 in) (O horizons)

Cambic horizon: 21 to 105 cm (8 to 41 in) (A, Bg, Bt, ABkb, and BC horizons)

Redoximorphic concentrations: 21 to 51 cm (8 to 20 in) and 105 to 200 cm (41 to 79 in) (A, Bg, Bt1, and Ck horizons)

Reduced matrix: 28 to 41 cm (11 to 16 in) (Bg horizon)

Free carbonates: 60 to 67 cm (24 to 26 in) and 105 to 200 cm (41 to 79 in) (ABkb and Ck horizons)

ADDITIONAL DATA:

User pedon ID: 2023AK180260

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National Cooperative Soil Survey
U.S.A.