LOCATION IGRUK AK
Established Series
SAS/MPS
11/2024
IGRUK SERIES
Depth class: very deep (moderately deep to permafrost)
Drainage class: poorly drained
Parent material: organic material over loess and organic cryoturbate over loess cryoturbate over organic material
Landscape: plains
Landform: drainageways
Microfeature: peat mounds
Slopes: 0 to 10 percent
Mean annual precipitation: about 400 mm (15.7 in)
Mean annual air temperature: about -3 degrees C. (27 degrees F.)
Frost-free period: 75 to 90 days
TAXONOMIC CLASS: Loamy, mixed, euic, subgelic Terric Sapristels
TYPICAL PEDON: Igruk highly decomposed material in a subarctic tundra community on a west facing microhigh on a convex, convex rise on a slope of 3 percent at an elevation of 31m (100 ft)
Oa--0 to 11 cm (0 to 4 in); highly decomposed plant material; black (7.5YR 2.5/1) moist, dark gray (7.5YR 4/1) dry; many very fine, fine, medium, coarse, and few very coarse roots throughout; extremely acid (pH 4.0); clear wavy boundary. (5 to 12 cm, 2 to 5 in thick)
Oajj--11 to 50 cm (4 to 20 in); muck; very dark brown (7.5YR 2.5/2) moist, brown (7.5YR 4/2) dry; 5 percent faint black (10YR 2/1) mottles; common very fine, fine, and few medium roots throughout; positive to alpha-alpha dipyridyl; very strongly acid (pH 4.7); abrupt irregular boundary. (30 to 40 cm, 12 to 16 in thick)
Oa/Ajj--50 to 72 cm (20 to 28 in); muck and very fine sandy loam; 70 percent black (7.5YR 2.5/1) and 30 percent dark brown (7.5YR 3/3) moist, 70 percent dark gray (7.5YR 4/1) and 30 percent brown (7.5YR 5/3) dry; weak medium granular structure; friable, slightly hard, nonsticky, nonplastic many very fine and few fine roots throughout; common very fine tubular pores; strongly acid (pH 5.1); clear irregular boundary. (10 to 23 cm, 4 to 9 in thick)
Ag/Oajjf--72 to 125 cm (28 to 49in); permanently frozen very fine sandy loam and permanently frozen muck; 60 percent very dark brown (7.5YR 2.5/2) and 40 percent black (7.5YR 2.5/1) moist, 60 percent brown (7.5YR 4/2) and 40 percent dark gray (7.5YR 4/1) dry; 5 percent faint black (10YR 2/1) mottles; weak medium granular structure; extremely firm, nonsticky, nonplastic; common very fine tubular pores; positive to alpha-alpha dipyridyl; noneffervescent; moderately acid (pH 5.7); very abrupt smooth boundary. (25 to 60 cm, 10 to 24 in thick)
Cg/Ajjf--125 to 140 cm (49 to 55 in); permanently frozen very fine sandy loam; 65 percent very dark grayish brown (2.5Y 3/2) and 35 percent dark reddish brown (5YR 3/3) moist, 65 percent grayish brown (2.5Y 5/2) and 35 percent reddish brown (5YR 5/3) dry; 5 percent distinct black (7.5YR 2.5/1) mottles; massive and weak medium platy structure; extremely firm, nonsticky, nonplastic; common very fine tubular pores; 5 percent 3 mm thick ice lenses; positive to alpha-alpha dipyridyl; noneffervescent; moderately acid (pH 5.9); very abrupt smooth boundary. (10 to 30 cm, 4 to 12 in thick)
Oaf--140 to 200 cm (55 to 79 in); permanently frozen muck; dark reddish brown (5YR 3/3) moist, reddish brown (5YR 5/3) dry; moderately acid (pH 5.6).
TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 64.9768240, longitude -160.8024640, datum WGS84, UTM north 7207084.21 and UTM east 414937.19, zone 4, datum WGS84.
RANGE IN CHARACTERISTICS:
Soil moisture regime: aquic
Soil temperature regime: gelic
Mean annual soil temperature: -2 to -1 degrees C. (28 to 30 degrees F.)
Thickness of organic material: 45 to 75 cm (18 to 30 in)
Thickness of sapric soil materials: 45 to 75 cm (18 to 30 in)
Thickness of cryoturbation: 45 to 125 cm (18 to 50 in)
Depth to reduced matrix: 45 to 75 cm (18 to 30 in)
Depth to permafrost: 45 to 100 cm (18 to 40 in)
Oa, Oajj horizons:
Hue: 5YR, 7.5YR, 10YR
Value: 2 or 2.5 moist, 4 dry
Chroma: 1 to 3
Texture: highly decomposed material, muck
Organic matter: 60 to 90 percent
Reaction class: extremely acid to moderately acid (pH 3.5 to 6)
Oa/Ajj horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3 moist, 4 or 5 dry
Chroma: 1 to 3
Texture: muck, very fine sandy loam
Sand: 15 to 65 percent
Silt: 27 to 80 percent
Clay: 2 to 8 percent
Organic matter: 60 to 90 percent
Reaction class: strongly acid to moderately acid (pH 5.1 to 6)
Ag/Oajjf horizon:
Hue: 7.5YR, 10YR
Value: 2 to 3 moist, 4 or 5 dry
Chroma: 1 to 3
Texture: permanently frozen silt loam, permanently frozen very fine sandy loam, permanently frozen muck
Sand: 15 to 65 percent
Silt: 27 to 80 percent
Clay: 2 to 8 percent
Organic matter: 2 to 6 percent
Reaction class: strongly acid to moderately acid (pH 5.1 to 6)
Cg/Ajjf horizon:
Hue: 7.5YR, 10YR, 2.5Y
Value: 2 to 4 moist, 4 to 6 dry
Chroma: 1 to 3
Texture: permanently frozen silt loam, permanently frozen very fine sandy loam
Sand: 15 to 75 percent
Silt: 17 to 80 percent
Clay: 2 to 8 percent
Organic matter: 1 to 3 percent
Reaction class: strongly acid to moderately acid (pH 5.1 to 6)
Oaf horizon:
Hue: 5YR, 7.5YR, 10YR
Value: 2 to 3 moist, 4 or 5 dry
Chroma: 1 to 3
Texture: permanently frozen muck
Organic matter: 60 to 90 percent
Reaction class: strongly acid to moderately acid (pH 5.1 to 6)
Horizon designations vary in some pedons due to cryoturbation.
COMPETING SERIES: This is the
Ugruk (AK) series.
Ugruk have long, frequent ponding, lack highly decomposed material at the soil surface, occur on dips or depressions on drainageways of plain, and have a mean annual precipitation range of 300 to 600 mm (12 to 24 in)
GEOGRAPHIC SETTING:
Elevation: 0 to 200 meters (0 to 655 feet)
Parent material: organic material over loess cryoturbate and/or organic material over loess cryoturbate over organic material
Landform: drainageways
Microfeature: peat mounds
Mean annual precipitation: 300 to 400 mm (12 to 16 in)
Mean annual air temperature: -5 to -1 degrees C. (23 to 30 degrees F.)
Frost free period: 75 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Apun,
Asulu,
Niilgik,
Nikaat,
Nunapik,
Nunavik,
Oldwomanriver,
Ryanlake,
Siku, and
Ugruk soils.
Apun soils have a histic epipedon, have a clay range of 5 to 18 percent, and occur on saddles, mountainbases, footslopes, and terrace treads
Asulu soils have a greater thickness of hemic soil materials, have a dysic reaction class, lack a reduced matrix, and occur on polygons of loess covered plains
Niilgik soils have a histic epipedon, have a clay range of 5 to 17 percent, have a pH range of 3.5 to 5.4, and occur on mountainbases and footslopes
Nikaat soils have a histic epipedon, can have volcanic glass, and occur on loess covered plains
Nunapik soils have a histic epipedon, have a cambic horizon, have a clay range of 6 to 25 percent, and occur on saddles, mounds on nose slopes or mountainflanks, upper third
Nunavik soils have an ochric epipedon, have a clay range of 3 to 17 percent, and occur on loess covered plains
Oldwomanriver soils lack permafrost, lack aquic conditions, lack cryoturbation, have an ochric epipedon, have a cambic horizon, have a sandy-skeletal substratum, have a cryic soil temperature regime, and occur on flood plains
Ryanlake soils have a greater thickness of hemic soil materials, have an isotic mineralogy class, lack a reduced matrix, and occur on terrace treads
Siku soils lack permafrost, have a folistic epipedon, have a cambic horizon, have 15 to 59 percent rock fragments, and occur on mountainflanks, upper, center, and lower thirds
Ugruk soils have long, frequent ponding, lack highly decomposed material at the soil surface, occur on dips or depressions on drainageways of plains
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: poorly drained
Saturation during normal years: saturated between 5 and 25 cm (2 and 10 in) during the growing season
Saturated Hydraulic Conductivity: very high in the Oa horizon, moderately high to high in the Oajj and Oa/Ajj horizons, and low to moderately low in the Ag/Oajjf, Cg/Ajjf, and Oaf horizons
Permeability: rapid to very rapid in the Oa horizon, moderate to moderately rapid in the Oajj and Oa/Ajj horizons, and very slow in the Ag/Oajjf, Cg/Ajjf, and Oaf horizons
Runoff: very high
USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: bog blueberry, sphagnum, marsh Labrador tea, tussock cottongrass, moss, dwarf birch, Bigelow's sedge, Flavocetraria cucullate, cetraria lichen, greygreen reindeer lichen, black crowberry, juniper polytrichum moss, cloudberry, reindeer lichen, Cetraria laevigata, alpine bearberry, lingonberry
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: 0 to 72 cm (0 to 28 in)
Sapric soil materials: 0 to 72 cm (0 to 28 in) (Oa, Oajj, and Oa/Ajj horizons)
Cryoturbation: 11 to 140 cm (4 to 55 in) (Oajj, Oa/Ajj, Ag/Oajjf, Cg/Ajjf horizons)
Gelic materials: 11 to 140 cm (4 to 55 in) (Oajj, Oa/Ajj, Ag/Oajjf, Cg/Ajjf horizons)
Reduced matrix: 72 to 140 cm (28 to 55 in) (Ag/Oajjf, Cg/Ajjf horizons)
Permafrost: 72 to 200 cm (28 to 79 in) (Ag/Oajjf, Cg/Ajjf, Oaf horizons)
Aquic conditions: 11 to 200 cm (4 to 79 in) (Oajj, Oa/Ajj, Ag/Oajjf, Cg/Ajjf, Oaf horizons)
ADDITIONAL DATA:
User pedon ID: 2022AK180541
The Igruk typical pedon classifies as a Terric Sapristel. 30 cm or more mineral soil material within 100 cm of the soil surface is needed for the terric subgroup. The Igruk typical pedon has 28 cm of mineral dominated soil horizon overlain by a cryoturbated horizon which is 30 percent mineral soil material and therefore makes up the 2 extra cm of thickness.
National Cooperative Soil Survey
U.S.A.