LOCATION SUSITNA                 AK

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

SUSITNA SERIES

Depth class: very deep
Drainage class: well drained
Parent material: loamy alluvium or loamy alluvium over sandy and gravelly alluvium
Landform: floodplains and stream terraces
Slopes: 0 to 8 percent
Mean annual precipitation: 15 to 30 inches
Mean annual temperature: 30 to 40 degrees F.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, nonacid Typic Cryofluvents

TYPICAL PEDON: Susitna silt loam -- on a 1 percent slope under native vegetation of mixed paper birch and white spruce forest at 300 feet elevation. (All colors are for moist soil)

Oe--0 to 1 inch; very dark brown (10YR 2/2) moderately decomposed plant material; many roots; strongly acid (pH 5.2); clear smooth boundary. (1 to 4 inches thick)

A--1 to 4 inches; dark brown (10YR 3/3) silt loam with common medium prominent reddish brown (5YR 4/4) mottles; weak medium granular structure; very friable, nonsticky and nonplastic; many roots; strongly acid (pH 5.4); clear smooth boundary. (1 to 4 inches thick)

C1--4 to 12 inches; dark grayish brown (10YR 4/2) fine sand stratified with silt and very fine sand with common large reddish brown (5YR 4/4) mottles; weak medium subangular blocky structure; very friable, nonsticky and nonplastic; strongly acid (pH 5.4); clear smooth boundary. (6 to 20 inches thick)

C2--12 to 34 inches; very dark grayish brown (10YR 3/2) fine sand stratified with silt and very fine sand with few fine prominent brown (7.5YR 4/4) mottles; massive; very friable, nonsticky and nonplastic; moderately acid (pH 5.6); gradual smooth boundary. (15 to 35 inches thick)

C3--34 to 52 inches; very dark grayish brown (2.5Y 3/2) and dark grayish brown (2.5Y 4/2) fine sand stratified with silt and very fine sand; few fine prominent yellowish red (5YR 4/6) mottles; massive; very friable, nonsticky and nonplastic; moderately acid (pH 5.6); gradual smooth boundary. (0 to 20 inches thick)

2C--52 to 60 inches; variegated extremely gravelly coarse sand; single grain; loose; nonsticky and nonplastic; 60 percent rounded gravel; moderately acid (pH 5.8).

TYPE LOCATION: Matanuska-Susitna Valley Area, Alaska; in the SE 1/4 of the NW 1/4 of section 34, T.26N., R.5W., Seward Meridian.

RANGE IN CHARACTERISTICS:
Upper mineral soil material: stratified textures of silt loam, loam, fine sandy loam, and loamy fine sand 40 to 60 inches thick
Depth to sands and gravels: 40 to greater than 50 inches
Particle size of the control section (weighted average): greater than 15 percent fine sand or coarser, less than 18 percent clay, and less than 35 percent coarse fragments
Total organic carbon: varies irregularly with increasing depth

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

A horizon:
Matrix color: hue of 10YR to 5Y; value of 2 to 4; chroma of 1 to 3
Texture: silt loam, fine sandy loam, loamy fine sand
Reaction class: very strongly acid to moderately acid

C horizons
Matrix color: hue of 10YR to 5Y; value of 3 to 6; chroma of 1 to 4
Mottles: reddish, brownish, or olive
Texture: stratified fine sand to silt loam, stratified loamy fine sand to silt loam
Individual strata thickness: less than 1 inch to 18 inches
Reaction class: strongly acid or moderately acid

2C horizon (where present):
Matrix color: variegated
Texture: sand, coarse sand, loamy sand modified by 0 to 70 percent total coarse fragments; 35 to 60 percent gravel, 0 to 20 percent cobbles
Reaction class: strongly acid to moderately acid

COMPETING SERIES: These are the Kluna, Petrof, Salchaket and Takotna(T) series. Kluna soils have slightly acid reaction in the 2C horizon. Petrof soils are moderately well drained. Salchaket soils contain large quantities of micaceous material. Takotna soils are calcareous within the control section.

GEOGRAPHIC SETTING:
Drainage class: well drained
Parent material: loamy alluvium or loamy alluvium over sandy and gravelly alluvium
Landform: floodplains and stream terraces
Slopes: 0 to 8 percent, soils are undulating in a few plces
Elevation ranges from 50 to 800 feet
Mean annual temperature: 30 to 40 degrees F.
Mean annual precipitation: 15 to 30 inches

GEOGRAPHICALLY ASSOCIATED SOILS: These are Moose River, Niklavar, and Susivar soils. Moose River and Niklavar soils are poorly drained and occur on flood plains. Susivar soils are somewhat poorly drained soils and occur on stream terraces.

DRAINAGE AND PERMEABILITY: Well drained, negligible to medium runoff. Saturated hydraulic conductivity is high in the loamy horizons and high to very in the gravelly underlying material. Susitna soils are subject to flooding.

USE AND VEGETATION: Mostly forested. Dominant trees are cottonwood (balsam poplar), paper birch, and white spruce. Cleared areas are used for bromegrass, timothy, oats, barley, potatoes, and hardy vegetables.

DISTRIBUTION AND EXTENT: MLRA 224 Cook Inlet Lowlands, South Central, Alaska. The soil is extensive.

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

SERIES ESTABLISHED: Soil Reconnaissance of Alaska. 1914.

REMARKS: Diagnostic features recognized in this profile include:
No diagnostic horizons
Total organic carbon: presumed irregular decrease based on colors, stratification, and occasional flooding
Coarse loamy particle size (weighted average): 10 to 40 inches
Temperature regime: cryic

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National Cooperative Soil Survey
U.S.A.