LOCATION AGITCHUK AK
Tentative Series
MPS
10/2024
AGITCHUK SERIES
Depth class: very deep
Drainage class: poorly drained
Parent material: mossy organic material over loamy slope alluvium derived from metamorphic and sedimentary rock
Landscape: hills
Landform: hillslopes
Slopes: 1 to 30 percent
Mean annual precipitation: about 400 mm (16 in)
Mean annual air temperature: about -4 degrees C. (24 degrees F.)
Frost-free period: 70 to 90 days
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, acid, subgelic Histic Gelaquepts
TYPICAL PEDON: Agitchuk peat in a black spruce with moss and shrub understory community on a south facing linear, linear toeslope on a slope of 6 percent at an elevation of 151m (495 ft)
Oi1--0 to 7 cm (0.0 to 3 in); peat; very dark brown (10YR 2/2) broken face moist, dark grayish brown (10YR 4/2) broken face dry; many very fine and fine roots throughout; ultra acid (pH 3.4); clear smooth boundary
Oi2--7 to 16 cm (3 to 6 in); peat; brownish yellow (10YR 6/6) broken face moist, yellow (10YR 8/6) broken face dry; many very fine and fine and common medium roots throughout; extremely acid (pH 3.8); abrupt smooth boundary. (combined thickness is 16 to 24 cm, 6 to 9 in thick)
Oa--16 to 21 cm (6 to 8 in); muck; black (10YR 2/1) broken face moist, dark gray (10YR 4/1) broken face dry; many very fine and fine and common medium roots throughout; extremely acid (pH 4.1); abrupt smooth boundary. (4 to 15 cm, 2 to 6 in thick)
Bg--21 to 49 cm (8 to 19 in); silt loam; dark grayish brown (10YR 4/2) broken face moist, light brownish gray (10YR 6/2) broken face dry; moderate very thin platy structure; friable, slightly hard, nonsticky, nonplastic; nonsmeary; moderately few very fine and fine roots throughout; common very fine dendritic tubular pores; 25 percent medium distinct irregular reddish brown (5YR 4/3), moist, masses of oxidized iron in matrix; noneffervescent; very strongly acid (pH 4.8); clear smooth boundary. (15 to 35 cm, 6 to 14 in thick)
Cg1--49 to 68 cm (19 to 27 in); silt loam; 85 percent dark grayish brown (10YR 4/2) broken face and 15 percent yellowish brown (10YR 5/4) broken face moist, 85 percent light brownish gray (10YR 6/2) broken face and 15 percent very pale brown (10YR 7/4) broken face dry; massive; friable, slightly hard, nonsticky, nonplastic; nonsmeary; common very fine roots throughout; many very fine dendritic tubular pores; 10 percent very fine prominent irregular brownish yellow (10YR 6/8), moist, masses of oxidized iron in matrix; 5 percent gravel; noneffervescent; very strongly acid (pH 5.0); abrupt wavy boundary. (15 to 30 cm, 6 to 12 in thick)
Cg/Ajj--68 to 120 cm (27 to 47 in); silt loam; 60 percent dark grayish brown (10YR 4/2) broken face and 40 percent very dark gray (10YR 3/1) broken face moist, 60 percent light brownish gray (10YR 6/2) broken face and 40 percent gray (10YR 5/1) broken face dry; massive, and weak fine granular structure; friable, slightly hard, slightly sticky, slightly plastic; nonsmeary; few very fine dendritic tubular pores; 10 percent fine distinct irregular brown (7.5YR 4/4), moist, masses of oxidized iron in matrix; 4 percent gravel; noneffervescent; strongly acid (pH 5.1); clear smooth boundary. (15 to 75 cm, 6 to 30 in thick)
Cg2--120 to 200 cm (47 to 79 in); silt loam; gray (10YR 5/1) broken face moist, light gray (10YR 7/1) broken face dry; massive; friable, slightly hard, nonsticky, slightly plastic; nonsmeary; few very fine dendritic tubular pores; 10 percent fine prominent irregular brown (7.5YR 4/4), moist, masses of oxidized iron in matrix; 10 percent gravel; noneffervescent; strongly acid (pH 5.2)
TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 64.2530833, longitude -160.1630277, datum WGS84, UTM north 7125731.73 and UTM east 443631.27, 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 (8 to 16 in)
Thickness of cambic horizon: 15 to 35 cm (6 to 14 in)
Depth to redoximorphic concentrations: 18 to 39 cm (7 to 15 in)
Depth to reduced matrix: 18 to 39 cm (7 to 15 in)
Oi and Oa horizons:
Hue: 5YR, 7.5YR, or 10YR
Value: 2 to 6 moist, 4 to 8 dry
Chroma:1 to 8
Texture: peat and muck
Organic matter: 60 to 90 percent
Reaction class: ultra acid to extremely acid (pH 3 to 4.4)
Bg horizon:
Hue: 10YR, 2.5Y, or 5Y
Value: 4 or 5 moist, 6 or 7 moist
Chroma: 1 or 2
Texture: silt loam, or sandy loam
Sand: 10 to 70 percent
Silt: 18 to 80 percent
Clay: 2 to 12 percent
Organic matter: 0.5 to 4 percent
Reaction class: very strongly acid to strongly acid (pH 4.5 to 5.4)
Cg horizons:
Hue: 10YR, 2.5Y, or 5Y
Value: 4 or 5 moist, 6 or 7 moist
Chroma: 1 or 2
Texture: silt, or silt loam
Sand: 10 to 45 percent
Silt: 50 to 88 percent
Clay: 2 to 10 percent
Rock fragments: 0 to 14 percent
Organic matter: 0.5 to 3 percent
Reaction class: very strongly acid to strongly acid (pH 4.5 to 5.4)
Cg/Ajj horizon:
Hue: 10YR, 2.5Y, or 5Y
Value: 3 to 5 moist, 5 to 7 dry
Chroma: 1 or 2
Texture: silt, or silt loam
Sand: 10 to 45 percent
Silt: 50 to 88 percent
Clay: 2 to 10 percent
Rock fragments: 0 to 10 percent
Organic matter: 0.5 to 6 percent
Reaction class: very strongly acid to strongly acid (pH 4.5 to 5.4)
COMPETING SERIES: none
GEOGRAPHIC SETTING:
Elevation: 50 to 375 meters (164 to 1230 feet)
Parent material: mossy organic material over loamy slope alluvium derived from metamorphic and sedimentary rock
Landform: hillslopes
Slopes: 1 to 30 percent
Mean annual precipitation: 300 to 500 mm (12 to 20 in)
Mean annual air temperature: -6 to -1 degrees C. (21.2 to 30.2 degrees F.)
Frost free period: 70 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Amigak, Fluffle,
Imak, Kilguk, Nappaktuk, Shovelcreek, Sikuruk, and
Stovecreek soils.
Amigak soils have a fine-loamy particle size class, have a clay range in the substratum from 16 to 35 percent, and occur on backslopes and footslopes
Fluffle soils have an ochric epipedon, have a cryic soil temperature regime, have a nonacid reaction class, lack cryoturbation, have frequent, long flooding, and occur on flood plains
Imak soils have permafrost, have an isotic mineralogy class, have a surface organic layer greater than 40 cm thick, and occur on footslopes, backslopes and shoulders
Kilguk soils have permafrost, have a folistic epipedon, lack a cambic horizon, have a coarse-silty particle size class, have a nonacid reaction class, and occur on thermokarst stream terraces
Nappaktuk soils have aquic conditions starting between 50 to 100 cm (20 to 39 in), have a mollic epipedon, have a cryic soil temperature regime, have an aniso class, lack cryoturbation, have occasional, brief flooding, and occur on flood plains
Shovelcreek soils have an ochric epipedon, have a sandy-skeletal particle size class, have a cryic soil temperature regime, lack aquic conditions, lack a cambic horizon, lack cryoturbation, and occur on flood plains and bars on flood plains
Sikuruk soils have permafrost, have a thicker organic surface, lack a cambic horizon, and occur on saddles, summits, shoulders and mountainflanks, center third
Stovecreek soils have an umbric epipedon, lack a cambic horizon, lack cryoturbation, have a cryic soil temperature regime, have an isotic mineralogy class, and occur on similar landforms on footslopes and toeslopes of drainageways
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: poorly drained
Saturation during normal years--saturated between 0 and 25 cm (0 and 10 in) during the growing season
Saturated Hydraulic Conductivity: High in the Oi and Oa horizons, moderately high to high in the Bg, Cg, and Cg/Ajj horizons
Permeability: moderate to moderately rapid in the Oi and Oa horizons, moderate to rapid in the Bg horizon, moderate in the Cg and Cg/Ajj horizons
Runoff: negligible
USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: sphagnum, cloudberry, Schreber's big red stem moss, bog blueberry, marsh Labrador tea, black spruce, dwarf birch, small cranberry, moss, Bigelow's 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)
Histic epipedon: 0 to 21cm (0 to 8 in) (Oi and Oa horizons)
Cambic horizon: 21 to 49 cm (8 to 19 in) (Bg horizon)
Redoximorphic concentrations: 21 to 200 cm (8 to 79 in) (Bg, Cg, and Cg/Ajj horizons)
Reduced matrix: 21 to 200 cm (8 to 79 in) (Bg, Cg, and Cg/Ajj horizons)
Cryoturbation: 68 to 120 cm (27 to 47 in) (Cg/Ajj horizon)
Aquic conditions: 0 to 200 cm (0 to 79 in) (Oi, Oa, Bg, Cg, and Cg/Ajj horizons)
ADDITIONAL DATA:
User pedon ID: 2021AK180731
National Cooperative Soil Survey
U.S.A.