LOCATION SILAGIKSAAK AK
Established Series
SAS/MPS
12/2024
SILAGIKSAAK SERIES
Depth class: very deep
Drainage class: somewhat poorly drained
Parent material: loamy slope alluvium over loamy colluvium derived from sandstone
Landscape: mountains
Landform: mountain slopes
Slope: 5 to 30 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: Fine-loamy, mixed, active, nonacid Aeric Cryaquepts
TYPICAL PEDON: Silagiksaak highly organic silt loam in a willow scrubland with field horsetail subalpine community on a northwest facing head slope with 18 percent slope at an elevation of 600m (1970 ft).
Oi--0 to 8 cm (0 to 3 in); slightly decomposed plant material; dark yellowish brown (10YR 3/4) moist, yellowish brown (10YR 5/4) dry; many very fine and fine roots throughout; slightly acid (pH 6.3); abrupt smooth boundary. (4 to 9 cm, 2 to 4 in thick)
Oa--8 to 12 cm (3 to 5 in); highly decomposed plant material; black (7.5YR 2.5/1) moist, dark gray (7.5YR 4/1) dry; many very fine and common fine roots throughout; slightly acid (pH 6.3); clear smooth boundary. (2 to 5 cm, 1 to 2 in thick)
A--12 to 17 cm (5 to 7 in); highly organic silt loam; very dark grayish brown (10YR 3/2) moist, brown (10YR 5/3) dry; weak medium granular structure; friable, slightly hard, nonsticky, nonplastic; nonsmeary; many very fine and few fine roots throughout; few very fine tubular pores; 1 percent fine prominent irregular strong brown (7.5YR 4/6) masses of oxidized iron in matrix; slightly acid (pH 6.2); clear smooth boundary. (3 to 10 cm, 1 to 4 in thick)
AB--17 to 29 cm (7 to 11 in); silt loam; brown (10YR 4/3) moist, pale brown (10YR 6/3) dry; weak medium subangular blocky structure; friable, slightly hard, slightly sticky, moderately plastic; nonsmeary; common very fine and few fine roots throughout; common very fine tubular pores; 1 percent medium faint irregular dark yellowish brown (10YR 4/4) masses of oxidized iron in matrix; moderately acid (pH 6.0); gradual smooth boundary. (5 to 15 cm, 2 to 6 in thick)
Bg1--29 to 49 cm (11 to 19 in); loam; dark grayish brown (10YR 4/2) moist, light brownish gray (10YR 6/2) dry; weak medium platy structure; firm, moderately hard, slightly sticky, moderately plastic; nonsmeary; few very fine and fine roots throughout; few very fine tubular pores; silt coats on surfaces along root channels; 25 percent coarse distinct irregular dark yellowish brown (10YR 4/4) masses of oxidized iron in matrix; slightly acid (pH 6.1); clear smooth boundary. (10 to 24 cm, 4 to 9 in thick)
Bg2--49 to 65 cm (19 to 26 in); silt loam; dark grayish brown (2.5Y 4/2) moist, light brownish gray (2.5Y 6/2) dry; weak coarse subangular blocky structure; friable, slightly hard, nonsticky, nonplastic; nonsmeary; few very fine roots throughout; few very fine tubular pores; 10 percent medium distinct irregular dark yellowish brown (10YR 4/4) masses of oxidized iron in matrix; moderately acid (pH 5.9); clear smooth boundary. (10 to 25 cm, 4 to 10 in thick )
Bw--65 to 130 cm (26 to 51 in); clay loam; olive brown (2.5Y 4/3) moist, light yellowish brown (2.5Y 6/3) dry; weak coarse subangular blocky structure; friable, slightly hard, slightly sticky, slightly plastic; nonsmeary; few very fine roots throughout; common very fine tubular pores; 3 percent fine prominent irregular dark yellowish brown (10YR 4/6) masses of oxidized iron in matrix; moderately acid (pH 5.6); clear smooth boundary. (50 to 80 cm, 20 to 32 in thick)
2C--130 to 200 cm (51 to 79 in); gravelly sandy clay loam; dark olive brown (2.5Y 3/3) moist, light olive brown (2.5Y 5/3) dry; massive; friable, slightly hard, slightly sticky, nonplastic; nonsmeary; few very fine roots throughout; few very fine tubular pores; 25 percent medium prominent irregular dark yellowish brown (10YR 4/6) masses of oxidized iron in matrix; 16 percent gravel; moderately acid (pH 6.0)
TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; Latitude 64.5284898 and Longitude -159.5292739; UTM North 7156013.31 and UTM East 474602.35; zone 4, datum WGS84.
RANGE IN CHARACTERISTICS:
Soil moisture regime: aquic
Soil temperature regime: cryic
Mean annual soil temperature: 0.0 to 2.5 degrees C. (31 to 37 degrees F.)
Thickness of organic material: 6 to 14 cm (2 to 6 in)
Thickness of ochric epipedon: 14 to 39 cm (6 to 15 in)
Thickness of cambic horizon: 78 to 154 cm (31 to 61 in)
Depth to redoximorphic concentrations: 13 to 24 cm (5 to 9 in)
Depth to redoximorphic depletions: 29 to 63 cm (11 to 25 in)
Oi and Oa horizons:
Hue: 7.5YR or 10YR
Value: 2 to 3 moist, 4 or 5 dry
Chroma: 1 to 4
Texture: slightly decomposed material, highly decomposed material
Organic matter: 60 to 90 percent
Reaction class: very strongly acid to slightly acid (pH 4.5 to 6.5)
A horizon:
Hue: 10YR
Value: 2 or 3 moist, 4 or 5 dry
Chroma: 1 to 3
Texture: highly organic silt, highly organic silt loam
Sand: 3 to 30 percent
Silt: 53 to 93 percent
Clay: 4 to 17 percent
Organic matter: 10 to 19 percent
Reaction class: very strongly acid to slightly acid (pH 4.5 to 6.5)
Hue: 10YR
Value: 2 to 4 moist, 4 to 6 dry
Chroma: 1 to 3
Texture: silt loam, loam, sandy loam
Sand: 5 to 65 percent
Silt: 15 to 83 percent
Clay: 5 to 27 percent
Organic matter: 2 to 8 percent
Reaction class: very strongly acid to slightly acid (pH 4.5 to 6.5)
Bg horizons:
Hue: 10YR, 2.5Y, 5Y
Value: 4 or 5 moist, 6 to 7 dry
Chroma: 2 to 4
Texture: silt loam, loam, clay loam
Sand: 20 to 45 percent
Silt: 25 to 72 percent
Clay: 8 to 30 percent
Organic matter: 0.5 to 5 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)
Bw horizon:
Hue: 10YR, 2.5Y, 5Y
Value: 4 or 5 moist, 6 to 7 dry
Chroma: 2 to 4
Texture: loam, clay loam
Sand: 20 to 45 percent
Silt: 23 to 53 percent
Clay: 20 to 32 percent
Organic matter: 0.5 to 5 percent
Reaction class: moderately acid to neutral (pH 5.6 to 7.3)
2C horizon:
Hue: 2.5Y or 10Y
Value: 3 or 4 moist, 5 or 6 dry
Chroma: 1 to 4
Texture: loam, sandy clay loam or their gravelly analogues
Sand: 25 to 75 percent
Silt: 0 to 50 percent
Clay: 10 to 25 percent
Rock fragments: 0 to 30 percent
Organic matter: 0.2 to 3 percent
Reaction class: moderately acid to slightly alkaline (pH 5.6 to 7.8)
Some pedons have a folistic epipedon with a thickness range of 14 to 21 cm (6 to 8 in).
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Elevation: 275 to 750 meters (900 to 2460 feet)
Parent material: loamy slope alluvium over loamy colluvium derived from sandstone
Landscape: mountains
Slope: 5 to 30 percent
Mean annual precipitation: 400 to 600 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
Apun, Egoosikcreek, Kalasikcreek,
Kikku,
Nagruk,
Ottercreek,
Uniat,
Urgiilik soils.
Apun soils have permafrost, have aquic conditions starting between 0 to 25 cm (0 to 10 in), have a histic epipedon, have cryoturbation, have a reduced matrix starting within 85 cm (24 in), lack a cambic horizon, have a coarse-loamy particle size class, have a gelic soil temperature regime, and occur on mountainbases, footslopes, saddles, and terrace treads
Egoosikcreek soils have a mollic epipedon, lack redox depletions with a chroma of 2 or less, have a gelic soil temperature regime, and occur on swales on mountainbases and swales on mountainflanks, center and lower thirds
Kalasikcreek soils have a paralithic contact at depths between 50 to 100 cm (20 to 40 in), lack aquic conditions, have a loamy-skeletal particle size class, have a gelic soil temperature regime, and occur on mountaintops and mountainflanks, upper third
Kikku soils have aquic conditions starting between 0 to 25 cm (0 to 10 in), have a histic epipedon, have a reduced matrix starting within 35 cm (14 in), have free carbonates below 40 cm (16 in), have a gelic soil temperature regime, and occur on shoulders and mountainflanks, upper third
Nagruk soils have a paralithic contact at depts between 50 to 100 cm (20 to 40 in), have a histic epipedon, have cryoturbation, and occur on saddles and mountainflanks, upper thirds
Ottercreek soils have aquic conditions starting between 0 to 25 cm (0 to 10 in), have a reduced matrix starting within 16 cm (6 in), lack a cambic horizon, have a coarse-loamy particle size class, and occur in valleys on mountainbases and mountainflanks, lower third
Uniat soils have a lithic contact at depths between 100 to 150 cm (40 to 60 in), have a fragmental layer starting at depths between 10 to 91 cm (4 to 36 in), lack aquic conditions, have a fragmental particle size class, and occur on mounds in valleys, mountaintops, and mountainflanks, upper third
Urgiilik soils have a lithic contact at depths between 50 to 100 cm (20 to 40 in), lack aquic conditions, have a loamy-skeletal particle size class, side slopes and mountainflanks, center third
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: somewhat poorly drained
Saturation during normal years: saturated between 25 and 50 cm (10 and 20 in) during the growing season
Saturated Hydraulic Conductivity: very high in the Oi and Oa horizons, moderately high to high in the A, AB, Bg1, and Bg2 horizons, and moderately high in the Bw and 2C horizons.
Permeability: rapid to very rapid in the Oi and Oa horizons, moderate to rapid in the A, AB, Bg1, and Bg2 horizons, and slow to moderately Bw and 2C horizons.
Runoff: very high
USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: field horsetail, tealeaf willow, splendid feather moss, moss, Richardson's willow, netleaf willow, arctic sweet coltsfoot, knights plume moss, Rocky mountain goldenrod, tall bluebells, boreal sagebrush, western arctic shootingstar, Altai fescue, bigelow's sedge, Langsdorf's lousewort, captiate valerian
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: 37 to 112 cm (15 to 44 in)
Ochric epipedon: 0 to 29 cm (0 to 11 in) (Oi, Oa, A, and AB horizons)
Cambic horizon: 12 to 130 cm (5 to 51 in) (A, AB, Bw1, Bg, and Bw2 horizons)
Redoximorphic concentrations: 17 to 200 cm (5 to 79 in) (AB, Bw1, Bg, Bw2, and 2C horizons)
Redoximorphic depletions with chroma of 2 or less: 49 to 65 cm (19 to 26 in) (Bg horizon)
Lithologic discontinuity: 130 to 200 cm (51 to 79 in) (2C horizon)
Aquic conditions: 29 to 65 cm (11 to 26 in) (Bg horizon)
ADDITIONAL DATA:
User pedon ID: 2021AK290601
National Cooperative Soil Survey
U.S.A.