LOCATION AHTNA                   AK

Established Series
SDB/MJS
08/2025

AHTNA SERIES

Depth class: very deep
Drainage class: well drained
Parent material: silty loess over clayey lacustrine deposits
Landscape: lake plains
Landform: bluffs and river valleys
Slopes: 30 to 70 percent
Mean annual precipitation: about 350 mm (14 in)
Mean annual air temperature: about -3 degrees C. (27 degrees F)
Frost-free period: 20 to 75 days

TAXONOMIC CLASS: Fine-loamy, mixed, semiactive Typic Calcicryepts

TYPICAL PEDON: Ahtna silt loam in white spruce forest communities on loess covered hillsides at 567m (1860 ft) elevation.

Oi--0 to 3 cm (0 to 1 in); slightly decomposed plant material, yellowish brown (10YR 5/4) dry, dark yellowish brown (10YR 3/4) rubbed moist; nonsticky, nonplastic; common very fine and fine, and many medium roots throughout; slightly acid (pH 6.4); abrupt smooth boundary. (2 to 8 cm, 1 to 3 in)

A--3 to 8 cm (1 to 3 in); silt loam, very dark grayish brown (10YR 3/2) broken face moist; moderate fine granular structure; slightly hard, friable, slightly sticky, nonplastic; nonsmeary; common very fine, fine, coarse, very coarse, and many medium roots throughout; very fine and fine irregular pores; slightly acid (pH 6.4); clear wavy boundary. (3 to 15 cm, 1 to 6 in)

Bw1--8 to 13 cm (3 to 5 in); silt loam, dark brown (7.5YR 3/3) broken face moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky, nonplastic; nonsmeary; common very fine, fine, medium, coarse, and very coarse roots throughout; very fine and fine irregular pores; neutral (pH 6.9); clear broken boundary. (3 to 15 cm, 1 to 6 in)

Bw2--13 to 35 cm (5 to 14 in); silt loam, brown (10YR 5/3) broken face moist; moderate medium subangular blocky structure; soft, very friable, slightly sticky, nonplastic; nonsmeary; common very fine, fine, medium, coarse, and very coarse roots throughout; very fine and fine irregular pores; 6 percent rounded gravel by volume; slight effervescence; neutral (pH 7.2); abrupt wavy boundary. (15 to 35 cm, 6 to 14 in)

2Bk1--35 to 65 cm (14 to 26 in); loam, gray (10YR 5/1) broken face moist; moderate fine granular structure; slightly hard, friable, slightly sticky, nonplastic; nonsmeary; common medium and fine roots throughout; very fine and fine irregular pores; 8 percent rounded gravel by volume; violent effervescence; slightly alkaline (pH 7.6); gradual smooth boundary. (15 to 40 cm, 6 to 16 in)

2Bk2--65 to 100 cm (26 to 39 in); clay loam, gray (10YR 5/1) broken face moist; moderate fine granular structure; soft, very friable, moderately sticky, moderately plastic; nonsmeary; common fine and medium roots throughout; very fine and fine irregular pores; 8 percent rounded gravel by volume; violent effervescence; moderately alkaline (pH 8.3); gradual smooth boundary. (20 to 40 cm, 8 to 16 in)

2C--100 to 200 cm (39 to 79 in); clay, gray (10YR 5/1) broken face moist; massive; moderately hard, firm; moderately sticky, moderately plastic; nonsmeary; very fine and fine irregular pores; 6 percent rounded gravel by volume; strong effervescence; moderately alkaline (pH 7.9). (47 to 142 cm, 19 to 56 in)

TYPE LOCATION: North Copper River Soil Survey Area, Alaska; latitude 62.48342, longitude -144.83066, Datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: udic
Soil temperature regime: cryic
Mean annual soil temperature: 0 to 5 degrees C. (32 to 41 degrees F)
Thickness of organic material: 2 to 8 cm (1 to 3 in)
Thickness of ochric epipedon: 3 to 15 cm (1 to 6 in)
Thickness of Calcic horizon: 35 to 80 cm (14 to 31 in)

Oi and Oe horizons:
Hue: 7.5YR or 10YR
Value: 2 to 3
Chroma: 1 to 2
Texture: slightly decomposed organic matter to moderately decomposed organic matter
Organic matter: 60 to 90 percent
Reaction class: strongly acid to neutral (pH 5.1 to 7.3)

A horizon:
Hue: 10YR or 2.5Y
Value:2 to 3
Chroma: 1to 3
Texture: silt loam
Sand: 10 to 45 percent
Silt: 50 to 80 percent
Clay: 4 to 15 percent
Organic matter: 2 to 6 percent
Reaction class: strongly acid to slightly alkaline (pH 5.5 to 7.8)

Bw horizons:
Hue: 10YR or 2.5Y
Value: 3 to 5
Chroma: 1 to 3
Texture: silt loam
Sand: 10 to 45 percent
Silt: 50 to 80 percent
Clay: 4 to 15 percent
Rock fragments: 0 to 10 percent gravels
Organic matter: 1 to 4 percent
Reaction class: slightly acid to moderately alkaline (pH 6.1 to 8.4)

Bk horizons:
Hue: 10YR or 2.5Y
Value: 3 to 5
Chroma: 1 to 2
Texture: Clay loam, silt loam, or loam
Sand: 15 to 52 percent
Silt: 25 to 67 percent
Clay: 18 to 30 percent
Rock fragments: 0 to 10 percent gravels
Organic matter: 1 to 3 percent
Calcium carbonate percentage: 15 to 20%
Reaction class: neutral to moderately alkaline (pH 6.6 to 8.4)

C horizon:
Hue:2.5Y or 5Y
Value: 4 to 6
Chroma: 1 to 2
Texture: clay to silty clay loam
Sand:5 to 35 percent
Silt: 20 to 68 percent
Clay: 27 to 45 percent
Rock fragments: 0 to 10 percent gravels
Organic matter: 0.5 to 2 percent
Reaction class: neutral to moderately alkaline (pH 6.6 to 8.4)

COMPETING SERIES: There are no competing series

GEOGRAPHIC SETTING:
Elevation: 400 to 800 meters (1310 to 2625 ft)
Parent material: silty loess over clayey lacustrine deposits
Landform: river valleys and bluffs
Slopes: 30 to 70 percent
Mean annual precipitation: 300 to 500mm (12 to 20 in)
Mean annual air temperature: -4 to -2 degrees C. (25 to 28 degrees F)
Frost free period: 20 to 75 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chelina, Crosswind, Detail and Tsana soils.
Chelina soils lack a calcic horizon and occur on former shorelines in lake plains.
Crosswind soils lack a calcic horizon, have aquic conditions within 50 cm (20 in), a cryoturbated horizon, permafrost, and occur on similar landforms in lake plains.
Detail soils lack a calcic horizon and occur on similar landforms in lake plains.
Tsana soils lack a calcic horizon, have less than 18 percent clay in the particle size control section, and occur on similar landforms in lake plains.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class: well
Saturated Hydraulic Conductivity: very high though the organic horizon, high in the A and Bw horizon, high to very high in the Bk horizon, moderately high in the C horizon.
Permeability: very rapid though the organic horizon, rapid in the A and Bw horizon, moderately rapid to rapid in the Bk horizon, moderately slow in the C horizon.
Runoff: high

USE AND VEGETATION:
Use: wildlife habitat, recreation, and subsistence
Native vegetation: White spruce, bebbs willow, feather moss

DISTRIBUTION AND EXTENT: MLRA 227 Copper River Basil.
Extent: limited

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Wasilla, Alaska

SERIES ESTABLISHED: North Copper River Soil Survey, Alaska, 2024.

REMARKS: Diagnostic features and horizons recognized in this profile include:

Particle-size control section: 33 to 108 cm (13 to 43 in)

Ochric epipedon: 8 to 38 cm (3 to 15 in) (Oi and A horizons)

Cambic horizon: 18 to 60 cm (7 to 24 in) (Bw1 and bw2 horizon)

Calcic horizon: 23 to 80 cm (9 to 31 in) (2Bk1 and 2Bk2 horizons)

Lithologic discontinuity: 127 to 177 cm (50 to 70 in) (C horizon)

ADDITIONAL DATA:

User pedon Id: 2016AK261048

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National Cooperative Soil Survey
U.S.A.