LOCATION AAGIAK AK

Established Series
MPS
11/2024

AAGIAK SERIES

Depth class: very deep
Drainage class: somewhat poorly drained
Parent material: loamy colluvium over gravelly loamy colluvium derived from mudstone
Landscape: mountains
Landform: mountain slopes
Slopes: 5 to 18 percent
Mean annual precipitation: about 500 mm (19.7 in)
Mean annual air temperature: about -4 degrees C. (25 degrees F.)
Frost-free period: 70 to 85 days

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, acid Humic Cryaquepts

TYPICAL PEDON: Aagiak gravelly silt loam in a willow subalpine community on a southwest facing linear, concave backslope on a slope of 12 percent at an elevation of 460m (1509 ft)

Oe--0 to 2 cm (0 to 1 in); moderately decomposed plant material; black (10YR 2/1) broken face moist, dark gray (10YR 4/1) broken face dry; many very fine and fine roots throughout; very strongly acid (pH 4.5); abrupt smooth boundary. (1 to 8 cm, 0.5 to 3 in thick)

A1--2 to 16 cm (1 to 6 in); gravelly silt loam; very dark grayish brown (10YR 3/2) broken face moist; grayish brown (10YR 5/2) broken face dry; moderate coarse subangular blocky structure; friable, slightly hard, nonsticky, nonplastic; nonsmeary; common very fine roots throughout; few very fine dendritic tubular pores; 20 percent gravel; noneffervescent; very strongly acid (pH 4.6); clear smooth boundary. (10 to 16 cm, 4 to 6 in thick)

A2--16 to 30 cm (6 to 12in); gravelly silt loam; very dark brown (10YR 2/2) broken face moist, dark grayish brown (10YR 4/2) broken face dry; moderate coarse subangular blocky parts to weak fine granular structure; friable, slightly hard, nonsticky, nonplastic; nonsmeary; common very fine roots throughout; few very fine dendritic tubular pores; 20 percent gravel; noneffervescent; very strongly acid (pH 5.0); clear wavy boundary. (8 to 16 cm, 3 to 6 in thick)

2Cg1--30 to 100 cm (12 to 39 in); very gravelly fine sandy loam; dark grayish brown (10YR 4/2) broken face moist, light brownish gray (10YR 6/2) broken face dry; massive; friable, slightly hard, nonsticky, nonplastic; nonsmeary; very few very fine roots throughout; common very fine dendritic tubular pores; 40 percent gravel; noneffervescent; strongly acid (pH 5.1). (50 to 90 cm, 20 to 35 in thick)

2Cg2--100 to 200 cm (39 to 79 in); extremely gravelly fine sandy loam; dark grayish brown (10YR 4/2) broken face moist, light brownish gray (10YR 6/2) broken face dry; massive; friable, slightly hard, nonsticky, nonplastic; nonsmeary; common very fine irregular pores; 65 percent gravel; noneffervescent; strongly acid (pH 5.3).

TYPE LOCATION: Nulato Hills - Continental Divide and Blackburn Hills Soil Survey Area, Alaska; latitude 64.4946738, longitude -160.2606248, datum WGS84, UTM north 7152740.31 and UTM east 439435.56, zone 4, datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: aquic
Soil temperature regime: cryic
Mean annual soil temperature: 0 to 3 degrees C. (32 to 37 degrees F.)
Thickness of organic material: 1 to 8 cm (0.5 to 3 in)
Thickness of umbric epipedon: 18 to 32 cm (7 to 13 in)
Depth to reduced matrix: 17 to 40 cm (7 to 16 in)

Oe horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 or 2
Texture: moderately decomposed material
Organic matter: 60 to 90 percent
Reaction class: extremely acid to strongly acid (pH 3.5 to 5.4)

A horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 3
Texture: silt loam or its gravelly analogue
Sand: 10 to 35 percent
Silt: 55 to 80 percent
Clay: 2 to 10 percent
Rock fragments: 0 to 30 percent
Organic matter: 2 to 8 percent
Reaction class: extremely acid to strongly acid (pH 3.5 to 5.4)

A2 horizon:
Hue: 7.5YR or 10YR
Value: 2 to 3 moist, 4 to 5 dry
Chroma: 1 to 3
Texture: silt loam, fine sandy loam or their gravelly analogues
Sand: 10 to 45 percent
Silt: 48 to 80 percent
Clay: 2 to 10 percent
Rock fragments: 0 to 30 percent
Organic matter: 2 to 8 percent
Reaction class: extremely acid to strongly acid (pH 3.5 to 5.4)

2Cg1 horizon:
Hue: 10YR or 2.5Y
Value: 4 or 5 moist, 6 to 7 dry
Chroma: 1 or 2
Texture: silt loam, fine sandy loam or their gravelly analogues
Sand: 15 to 55 percent
Silt: 33 to 80 percent
Clay: 2 to 12 percent
Rock fragments: 15 to 59 percent
Organic matter: 0.4 to 3 percent
Reaction class: extremely acid to strongly acid (pH 3.5 to 5.4)

2Cg2 horizon:
Hue: 10YR or 2.5Y
Value: 4 or 5 moist, 6 to 7 dry
Chroma: 1 or 2
Texture: silt loam, fine sandy loam or their gravelly analogues
Sand: 15 to 60 percent
Silt: 28 to 80 percent
Clay: 2 to 12 percent
Rock fragments: 35 to 75 percent
Organic matter: 0.4 to 3 percent
Reaction class: extremely acid to strongly acid (pH 3.5 to 5.4)

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING:
Elevation: 350 to 550 meters (1150 to 1805 feet)
Parent material: loamy colluvium over gravelly loamy colluvium derived from mudstone
Landform: mountain slopes
Slopes: 5 to 18 percent
Mean annual precipitation: 400 to 500 mm (16 to 20 in)
Mean annual air temperature: -6 to -2 degrees C. (21to 30 degrees F.)
Frost free period: 70 to 85 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Apkun, Apun, Fluffle, Iyyagrik, Managaarak and Siku soils.
Apkun soils have a lithic contact at depths between 50 to 100 cm (20 to 40 in), lack aquic conditions, have a fragmental layer starting between 35 to 84 cm (14 to 33 in), have a gelic soil temperature regime, and occur on mountainflanks, upper and center thirds
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 coarse-loamy particle size class, have a nonacid reaction class, have a gelic soil temperature regime, and occur on terraces, footslopes, saddles, and mountainbases
Fluffle soils have aquic conditions starting between 0 to 25 cm (0 to 10 in), have an ochric epipedon, have a cambic horizon, have a coarse-loamy particle size class, have a nonacid reaction class, and occur on flood plains
Iyyagrik soils have a lithic contact at depths between 100 to 150 cm (40 to 60 in), lack aquic conditions, have a mollic epipedon, have a pH range of 5.5 to 7.3 in the mineral horizons, and occur on mountainflanks, upper third
Managaarak soils have a lithic contact at depths between 100 to 150 cm (40 to 60 in), lack aquic conditions, have a fragmental layer starting between 41 to 93 cm (16 to 37 in), have an ochric epipedon, have a gelic soil temperature regime, and occur on mountainflanks, upper third
Siku soils have aquic conditions starting between 0 to 25 cm (0 to 10 in), have a folistic epipedon, have a cambic horizon, have a gelic soil temperature regime, and occur on mountainflanks, upper, center, and lower thirds

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 Oe horizon, moderately high in the A1 horizon, and moderately high to high in the A2, 2Cg1, and 2Cg2 horizons
Permeability: rapid to very rapid in the Oe horizon, moderate in the A1 horizon, and moderate to rapid in the A2, 2Cg1, and 2Cg2 horizons
Runoff: very high

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: tealeaf willow, bluejoint, woodland horsetail, moss, yellow thimbleweed, dwarf raspberry, larkspurleaf monkshood, heartleaf saxifrage

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: 27 to 102 cm (11 to 40 in)

Umbric epipedon: 2 to 30 cm (1 to 12 in) (A1 and A2 horizons)

Reduced matrix: 30 to 200 cm (12 to 79 in) (2Cg1 and 2Cg2 horizons)

Lithologic discontinuity: 30 to 200 cm (12 to 79 in) (2Cg1 and 2Cg2 horizons)

Aquic conditions: 30 to 200 cm (12 to 79 in) (2Cg1 and 2Cg2 horizons)

ADDITIONAL DATA:

User pedon ID: 2021AK180737

National Cooperative Soil Survey
U.S.A.