LOCATION MANKOMEN                AK

Established Series
Rev. MHC-JPM
05/2022

MANKOMEN SERIES

The Mankomen series consists of very shallow or shallow over permafrost, very poorly or poorly drained soils formed in sandy lacustrine strandline deposits. Mankomen soils are on lacustrine terraces. Slopes range from 0 to 10 percent. Mean annual temperature is about 26 degrees F., and the average annual precipitation is about 16 inches.

TAXONOMIC CLASS: Sandy, mixed, subgelic Typic Aquiturbels

TYPICAL PEDON: Mankomen peat on a 5 percent slope under dwarf black spruce forest at 1900 feet elevation. (All colors are for moist soil)

Oi--0 to 7 inches; dark reddish brown (5YR 3/3) peat; raw fibrous moss, twigs, and toot fibers; gradual smooth boundary. (4 to 10 inches thick)

Oe--7 inches to 15; black (10YR 2/1) mucky peat; partially decomposed moss, twigs, and root fibers; diffuse irregular boundary. (4 to 8 inches thick)

Cg/Oa--15 to 20 inches; very dark gray (5Y 3/1) loamy sand and black (10YR 2/1) muck; weak medium subangular blocky structure; very friable, nonsticky and nonplastic; common very fine and fine roots; moderately acid (pH 6.0); diffuse wavy boundary. (0 to 6 inches thick)

Cg--20 to 39 inches; dark olive gray (5Y 3/2) and olive (5Y 4/4) sand; single grain; loose, nonsticky and nonplastic; common medium faint dark gray (5Y 4/1) redox depletions; slightly acid (pH 6.4); gradual wavy boundary. (6 to 20 inches thick)

C--39 to 42 inches; dark grayish brown (2.5Y 4/2) loamy sand; single grain; loose, nonsticky and nonplastic; slightly acid (pH 6.4); gradual wavy boundary. (0 to 10 inches thick)

Cf--42 to 52 inches; dark grayish brown (2.5Y 4/2) loamy sand; slightly acid (pH 6.4); frozen on August 29, 1992.


TYPE LOCATION: Gulkana River Area, Alaska; about 3 miles northwest of Sourdough; the NE1/4 of the NE1/4 of section 11, T.9N., R.2W., Copper River Meridian.

RANGE IN CHARACTERISTICS: The organic mat ranges from 8 to 16 inches thick. Permafrost is at 3 to 35 inches below the surface of the mineral soil. The particle size control section is sandy.

The O horizons have a reaction of moderately acid or slightly acid

The Cg and Cg/O horizons are separated into their respective parts; the Cg part has hue of 10YR, 2.5Y, 5Y, or 5GY; value moist of 2, 3, or 4; chroma moist of 1 or 2. Texture is fine sandy loam, loamy sand, or sand. The O part (when present) has value moist of 2 or 3; chroma of 1 or 2. Texture is muck or mucky peat. Rock fragments range from 0 to 20 percent gravel. Reaction is moderately acid to neutral. Mottles (when present) have hue 5Y or 5GY; chroma moist of 3 or 4; chroma of 1, or 2

The C horizon has hue of 10YR, 2.5Y, or 5Y; value moist of 2, 3, or 4; chroma moist of 1 or 2. Texture is fine sand, loamy fine sandy, loamy sand, and sand. Rock fragments range from 0 to 5 percent gravel. Reaction is slightly acid to mildly alkaline.

COMPETING SERIES: These are the Copper River, Deborah (T) Mendeltna, Saulich, and Tolsona series in the same subgroup. Copper River, Deborah, and Saulich soils have silty textures with less than 15 percent fine sand of coarser. Mendeltna soils have loamy textures with more than 18 percent clay. Tolsona soil have loamy textures with less than 18 percent clay.

GEOGRAPHIC SETTING: The Mankomen soils are on lacustrine terraces. The soils formed in sandy lacustrine strandline deposits. The climate is subarctic continental with an average annual precipitation of about 16 inches. Mean annual temperature is 26 degrees F. Slopes range from 0 to 10 percent.

DRAINAGE AND PERMEABILITY: Very poorly or poorly drained. Slow to medium runoff. Permeability is rapid in the organic materials and unfrozen mineral soil and impermeable in the permafrost.

USE AND VEGETATION: The Mankomen soils are used for wildlife habitat. The native vegetation is dominantly black spruce forest.

DISTRIBUTION AND EXTENT: Southcentral Alaska. The series is of small extent.

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

SERIES ESTABLISHED: Gulkana River Area, Alaska. 1999.

REMARKS: Diagnostic horizons and features recognized in this profile include: organic material from 15 inches to 0; mineral material from 0 to 27 inches with a control section that is sandy; redoximorphic features from 0 to 24 inches; pH of 5.0 (0.01M CaCl2) or greater in all parts of the control section; permafrost at 27 inches.

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National Cooperative Soil Survey
U.S.A.