LOCATION AFOGNAK                 AK

Tentative Series
Rev. CAP
04/2024

AFOGNAK SERIES

Depth class: Shallow
Drainage class: Well drained
Parent material: herbaceous organic material over sandy and loamy volcanic ash over medial silty volcanic ash over residuum weathered from graywacke
Landscape: Islands
Landform: Mountains, hills, and ridges
Slopes: 0 to 80 percent
Mean annual precipitation: about 2250 mm (88.5 in)
Mean annual air temperature: about 2 degrees C. (34 degrees F.)

TAXONOMIC CLASS: Medial, ferrihydritic Lithic Humicryods

TYPICAL PEDON: Afognak ashy loamy fine sandy in Sitka spruce woodland with grass understory at an elevation of 165 meters (545 feet). (All colors are for moist soil unless noted.

Oe--0 to 4 cm (0 to 2 in); moderately decomposed plant material, dark reddish gray (5YR 4/2) dry, dark reddish brown (5YR 3/2) moist; very friable, soft, nonsticky, nonplastic; common very fine, fine, medium, and coarse roots throughout; extremely acid (pH 4.3); abrupt smooth boundary. (2 to 15 cm, 1 to 6 in thick)

C--4 to 16 cm (2 to 6 in); ashy loamy fine sand, very pale brown (10YR 8/2) dry, 60 percent light gray (10YR 7/1) and 25 percent brownish yellow (10YR 6/6) moist; single grain; very friable, soft, nonsticky, nonplastic; very few very fine and fine roots and common coarse and medium roots throughout; very strongly acid (pH 4.8); abrupt smooth boundary. (2 to 15 cm, 1 to 6 in thick)

2A--16 to 25 cm (6 to 10 in); medial silt loam, black (10YR 2/1) moist; weak fine granular structure; very friable, soft, nonsticky, nonplastic; common very fine and fine and many medium and coarse roots throughout; 5 percent gravel; very strongly acid (pH 4.7); clear smooth boundary. (2 to 13 cm, 1 to 5 in thick)

2Bhs--25 to 45 cm (10 to 18 in); medial highly organic silt loam; weak fine subangular blocky structure; friable, slightly hard, nonsticky, nonplastic; common very fine, fine, medium, and coarse roots throughout; 10 percent gravel; very strongly acid (pH 5.0); abrupt wavy boundary. (2 to 15 cm, 1 to 6 in thick)

3R--45 to 70 cm (18 to 28 in); strongly to indurated bedrock derived from greywacke.

TYPE LOCATION: Kodiak Archipelago Soil Survey Area, Alaska; Latitude 58 degrees 15 minutes 58.64 seconds and Longitude 152 degrees 35 minutes 2.80 seconds west, UTM north 648432.93 and UTM east 524400.00, zone 5, Datum WGS84.

RANGE IN CHARACTERISTICS:

Soil moisture regime: Udic
Mean annual soil temperature: 1.6 to 3.3 degrees C. (34.8 to 37.9 degrees F.)
Thickness of organic material: 2 to 15 cm (1 to 6 in)
Thickness of 1912 Ash: 2 to 15 cm (2 to 6 in)
Depth to andic properties: 4 to 30 cm (2 to 12 in)
Depth to spodic horizon: 6 to 43 cm (2 to 17 in)
Depth to lithic contact: 20 to 50 cm (8 to 20 in)

Oa, Oe, Oi horizon:
Hue: 7.5YR to 10 YR
Value: 2 to 5
Chroma: 1 to 4
Texture: slightly, moderately, or highly decomposed plant material
Organic matter: 60 to 90 percent
Reaction class: extremely acid to moderately acid (pH 3.5 to 6.0)

C horizon:
Hue: 7.5 YR to 10 YR
Value: 4 to 8
Chroma: 1 to 6
Texture: (ashy and glassy) sand, loamy sand, loamy fine sand, very fine sandy loam, sandy loam, or silt loam
Sand: 30 to 90 percent
Clay: 2 to 8 percent
Silt: 10 to 55 percent
Reaction Class: extremely acid to moderately acid (pH 3.5 to 6.0)

2A horizon:
Hue: 5YR, 7.5YR, or 10YR
Value: 2 to 5
Chroma: 1 to 3
Texture: (medial) silt loam, silt, loam, or very fine sandy loam
Silt: 40 to 90 percent
Clay: 2 to 10 percent
Rock Fragments: 0 to 14 percent
Reaction Class: extremely acid to moderately acid (pH 3.5 to 6.0)

2Bhs or 2Bs horizon:
Hue: 5YR, 7.5YR, or 10YR
Value: 2 or 3
Chroma: 1 to 4
Texture: (medial) silt loam, silt, loam, or very fine sandy loam, or their gravelly analogues
Silt: 40 to 90 percent
Clay: 2 to 12 percent
Rock Fragments: 0 to 25 percent
Reaction Class: extremely acid to moderately acid (pH 3.5 to 6.0)

3R horizon: Strongly to indurated bedrock derived from graywacke.

Some pedons have lithic contacts at depths greater than 50 cm (20 in) and/or skeletal till substratum above the lithic contact.

COMPETING SERIES: These are the Nakochina, Tutka, and Verstovia series.
Nakochina soils lack the 1912 volcanic ashy surface horizon and average precipitation is less than 1270mm (50 in).
Tutka soils lack the 1912 volcanic ashy surface horizon.
Verstovia soils lack the 1912 ashy surface horizon and have mean annual temperature greater than 2 degrees C. (34 degrees F.)

GEOGRAPHIC SETTING:
Elevation: 100 to 1300 meters (325 to 4300 feet)
Parent material: decomposed organic material over sandy and loamy volcanic ash over medial silty volcanic ash over residuum weathered from graywacke
Landform: mountains, hills, and ridges on summits, shoulders, and back slopes or flanks
Slope: 0 to 80 percent
Mean annual temperature: about 2 degrees C. (34 degrees F.)
Mean annual precipitation: about 2250 mm (88.5 inches)
Frost free period: 20 to 50 days

GEOGRAPHICALLY ASSOCIATED SOILS: These include Kaguyak, Kazakof, Kodiak, Marka, Port Lions, Pyramid, and Shuyak.
Kaguyak soils lack spodic horizons, have skeletal control sections, and occur are similar landform positions.
Kazakof soils have are moderately deep to lithic contact, and occur on similar landform positions.
Kodiak soils lack lithic contacts, have loamy skeletal till substratum, and occur on flanks, backslopes, and foot slopes.
Marka soils have lithic contacts greater than 50 cm (20 in), have loamy skeletal till substratum, and occur on similar landform positions.
Port Lions soils have lithic contacts greater than 50 cm (20 in) and occur on similar landform positions.
Pyramid soils have skeletal control sections and occur on similar landform positions.
Shuyak soils lack spodic horizons and occur are similar landform positions.

DRAINAGE AND PERMEABILITY:
Drainage class: well drained
Saturated Hydraulic Conductivity: very high in the C horizon and moderately high to high in the 2A and Bhs horizons.
Permeability: rapid to very rapid in the C horizon and moderately rapid to rapid in the 2A and Bhs horizons.
Runoff: high to very high.

USE AND VEGETATION:
Used for rangeland on slopes less than 45%. The native vegetation includes Sitka spruce, salmonberry, devils club, moss, alder, dwarf dogwood, Canada goldenrod, fireweed, tufted hairgrass, bluejoint grass, red fescue, and geraniums.

DISTRIBUTION AND EXTENT: MLRA 220, Kodiak Archipelago, Alaska.
Extent: moderate.

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

SERIES ESTABLISHED: Kodiak Archipelago Soil Survey, Alaska, 1960.

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

Organic material: 0 to 4 cm (0 to 2 in) (moderately decomposed hemic plant material) (Oe horizon)

1912 volcanic glass (ashy) material: 4 to 16 cm (2 to 6 in) (C horizon)

Andic soil properties: 16 to 45 cm (6 to 18 in) (2A and Bhs horizons)

Spodic horizon: 25 to 45 cm (10 to 18 in) (Bhs horizon)

Lithic contact: 45 to 70 cm (18 to 28) (3R horizon)

Source of the volcanic ash is the 1912 eruption of Mt. Novarupta and Mt. Katmai on the Alaska Peninsula.

ADDITIONAL DATA:

User pedon Id: 08AO 03901

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National Cooperative Soil Survey
U.S.A.