LOCATION TOKOSITNA               AK

Established Series
Rev. MHC/JPM/DLM
02/2022

TOKOSITNA SERIES

Depth class: very deep
Drainage class: well drained
Parent material: volcanic ash and loess deposits overlying friable to firm gravelly glacial till
Landform: till plains, hills, and hillslopes
Slopes: range from 0 to 60 percent
Mean annual precipitation: is about 28 inches.
Mean annual temperature: is about 33 degrees F.

TAXONOMIC CLASS: Medial over loamy-skeletal, amorphic over mixed, superactive Andic Haplocryods

TYPICAL PEDON: Tokositna silt loam - on a 15 percent slope under paper birch and white spruce forest at 800 feet elevation. (All colors are for moist soil, textures are apparent field textures)

Oi--0 to 2 inches; very dusky red (2.5YR 2.5/2) slightly decomposed plant material; common very fine, fine, medium roots; extremely acid (pH 4.3). (1 to 3 inches thick)

E--2 to 4 inches; grayish brown (10YR 5/2) silt loam; weak fine granular structure; very friable, nonsticky and nonplastic; common very fine, fine and medium and few coarse roots; very strongly acid (pH 4.6); abrupt wavy boundary. (1 to 3 inches thick)

Bhs--4 to 6 inches; dark reddish brown (5YR 3/3) mucky silt loam; weak fine subangular blocky structure; very friable, nonsticky and nonplastic; common very fine, fine and medium and few coarse roots; very strongly acid (pH 4.6); clear wavy boundary. (0 to 3 inches thick)

Bs--6 to 14 inches; strong brown (7.5YR 5/6) silt loam; weak medium subangular blocky structure; very friable, nonsticky and nonplastic; common very fine and fine roots; very strongly acid (pH 5.0); abrupt wavy boundary. (4 to 9 inches thick)

Eb--14 to 15 inches; brown (7.5YR 5/4) silt loam; weak fine granular structure; very friable, nonsticky and nonplastic; few very fine and fine roots; very strongly acid (pH 5.0); abrupt wavy boundary. (0 to 3 inches thick)

Bsb--15 to 23 inches; brown (7.5YR 4/4) silt loam; weak coarse subangular blocky structure; very friable, nonsticky and nonplastic; few very fine roots; very strongly acid (pH 5.0); gradual wavy boundary. (0 to 10 inches thick)

BC--23 to 30 inches; brown (10YR 4/3) silt loam; weak coarse subangular blocky structure; very friable, nonsticky and nonplastic; few very fine roots; strongly acid (pH 5.2); clear smooth boundary. (4 to 9 inches thick)

2C1--30 to 39 inches; very dark grayish brown (10YR 3/2) and dark grayish brown (10YR 4/2) very cobbly sandy loam; common medium distinct mottles of strong brown (7.5YR 4/6); massive; friable, slightly sticky and slightly plastic; 20 percent rounded and subangular gravel and 15 percent rounded and subangular cobble; moderately acid (pH 5.6); gradual smooth boundary. (9 to 22 inches thick)

2C2--39 to 60 inches; dark grayish brown (10YR 4/2) very cobbly loam; massive; firm, slightly sticky and slightly plastic; 20 percent rounded and subangular gravel and 15 percent rounded and subangular cobble; moderately acid (pH 6.0).

TYPE LOCATION: Susitna Valley Area, Alaska; about 2 miles east of Talkeetna; the SE 1/4 of the SW 1/4 of section 21, T. 26, R. 4W., Seward Meridian.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 33 to 36 degrees F.
Thickness of the loess mantle and depth to glacial till: 16 to 35 inches
Stratas of volcanic ash: occur throughout the loess mantle
Bulk density of loess mantle: presumed to be less then 0.90 grams per cubic centimeter
Phosphorous retention of loess mantle: presumed to be greater than 85 percent
Upper 4 inches of spodic horizons: less than 6 percent total organic carbon

O horizon:
Matrix color: 7.5YR or 10YR; value of 2 or 3; chroma of 1 to 4
Reaction class: extremely acid or strongly acid

E and Eb horizons:
Matrix color: hue of 7.5YR or 10YR; value of 4 or 5; chroma of 2 to 4
Texture: silt loam, very fine sandy loam
Reaction class: extremely acid to strongly acid

Bhs horizon:
Matrix color: hue of 2.5YR or 5YR; value of 2 or 3; chroma of 2 or 3
Texture: mucky silt loam, mucky very fine sandy loam, mucky sandy loam, mucky loam
Total organic carbon: 6 to 12 percent
Weakly cemented fragments and concretions: are often present
Reaction class: extremely acid to strongly acid

Bs and Bsb horizons:
Matrix color: hue of 5YR or 7.5YR; value of 4 or 5; chroma of 4 to 8
Texture: silt loam, very fine sandy loam, sandy loam, loam
Total organic carbon: less than 6 percent
Reaction class: extremely acid to strongly acid

BC horizon:
Matrix color: hue of 10YR or 2.5Y; value of 3 or 4; chroma of 2 to 4
Texture: silt loam, very fine sandy loam
Coarse fragments: occasional gravel and cobbles
Reaction class: extremely acid to strongly acid

2C horizon:
Matrix color: hue of 10YR to 5Y; value of 3 or 4; chroma of 2 or 3
Textures: sandy loam, loam modified by 35 to 55 percent rounded and subangular total coarse fragments; 15 to 45 percent gravel, 0 to 20 percent cobbles, 0 to 3 stones
Reaction class: moderately acid or strongly acid

COMPETING SERIES: This is the Estelle series. Estelle soils lack spodic horizons with greater than 6 percent total organic carbon.

GEOGRAPHIC SETTING:
Drainage class: well drained
Parent material: volcanic ash and loess deposits overlying friable to firm gravelly glacial till
Landform: till plains, hills, and hillslopes
Slopes: range from 0 to 60 percent
Climate: transitional maritime-continental
Mean annual temperature: is about 33 degrees F.
Mean annual precipitation: is about 28 inches.

GEOGRAPHICALLY ASSOCIATED SOILS:

DRAINAGE AND PERMEABILITY: Well drained, very low to high runoff. Saturated hydraulic conductivity is moderately high to high in the loess mantle and moderately high in the underlying glacial till.

USE AND VEGETATION: Used for cropland, pasture, and wildlife habitat. The native vegetation includes white spruce and paper birch.

DISTRIBUTION AND EXTENT: MLRA 224 Cook Inlet Lowlands, South-central Alaska. The series is of moderate extent.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: WASILLA, ALASKA

SERIES ESTABLISHED: Matanuska-Susitna Area, Alaska. 1996.

REMARKS: Diagnostic horizons and features recognized in this profile include:
Albic horizons: from 2 to 4 and 14 to 15 inches
Spodic horizons from 4 to 14 and 15 to 23 inches
Presumed andic properties: from 2 to 30 inches
Loamy-skeletal particle size from: 30 to 60 inches
Temperature regime: cryic

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National Cooperative Soil Survey
U.S.A.