LOCATION MANCHU                  AK

Established Series
Rev. DKS/JM/DLM
05/2022

MANCHU SERIES

Depth class: moderately deep
Drainage class: moderately well drained
Parent material: micaceous loess overlying weathered schist bedrock
Landform: hills
Slopes: 3 to 70 percent
Mean annual temperature: about 26 degrees F., -3.3 C.
Mean annual precipitation: about 12 inches, 305 mm

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive Aquic Haplocryepts

TYPICAL PEDON: Manchu silt loam -- under black spruce forest (All colors are for moist soil)

Oi--0 to 6 inches (0 to 16 cm); very dark brown (7.5YR 2.5/3) slightly decomposed organic matter; many very fine to coarse roots; extremely acid (pH 4.2); clear smooth boundary. (Thickness of the O horizon is 4 to 11 inches (9 to 28 cm))

A--6 to 8 inches (16 to 19 cm); black (10YR 2/1) silt loam; weak fine granular structure; friable, slightly sticky and slightly plastic; few very fine and fine roots; strongly acid (pH 5.2); clear wavy boundary. (Thickness of the A horizon is 1 to 8 inches (3 to 21 cm))

Bw--8 to 17 inches (19 to 42 cm); 80% dark yellowish brown (10YR 4/4) and 20% dark gray (2.5Y4/1) silt loam; common fine prominent yellowish red (5YR 4/6) mottles; moderate thin platy structure friable; slightly sticky and slightly plastic; few fine and very fine roots; moderately acid (pH 5.6); clear wavy boundary. (8 to24 inches thick (20 to 60 cm))

BC--17 to 28 inches (42 to 70 cm); 60% light olive brown (2.5Y 5/4) and 40% dark yellowish brown (10YR4/6) silt loam; weak thin platy structure; friable; slightly sticky and slightly plastic; 5 percent channers; slightly acid (pH 6.4); gradual smooth boundary. (4 to 8 inches thick where present (10 to 20 cm))

2BCr--28 to 39 inches (70 to 100 cm); dark yellowish brown (10YR 4/4) extremely channery silt loam; massive; friable; slightly sticky and slightly plastic; 50 percent channers and 20 percent flags; neutral (pH 6.6);

2Cr--39 to 60 inches (100 to 152 cm); dark yellowish brown (10YR 4/4) extremely channery sandy loam (weathered schist bedrock); massive; friable; nonsticky and nonplastic; 50 percent channers and 20 percent flags; slightly acid (pH 6.4).

TYPE LOCATION: Fort Wainwright Area, Alaska; UTM zone 6, 514477E 7164398N (description taken from transect 00DS021 stop 4)

RANGE IN CHARACTERISTICS:
Thickness of the organic mat: 4 to 11 inches (9 to 28 cm)
Particle size control section (weighted average): 15 to 35 percent coarse fragment, dominantly schist channers and/or flagstones, and less than 18 percent clays and greater than 15 percent fine sands and coarser
Depth to weathered schist bedrock: 20 to 39 inches (50 to 100 cm) from the mineral soil surface
Mica content: substantial amounts of mica

O horizon:
Matrix color: hue of 5YR to 10YR, value of 2 to 4, and chroma of 1 to 3
Texture: slightly or moderately decomposed plant material
Reaction class: extremely acid to very strongly acid

A horizon:
Matrix color: hue of 7.5YR or 10YR; value of 2 to 4; chroma of 1 to 3 Texture: silt loam or mucky silt loam
Reaction class: very strongly acid or strongly acid.

Bw horizon:
Matrix color: hue of 10YR or 2.5Y, value of 3 to 4; chroma of 1 to 4
Texture: silt loam or silt
Coarse fragments: 0 to 10 percent
Reaction class: strongly or moderately acid.

2 BCr or 2Cr horizons:
Matrix color: hue from 10YR to 5Y; value of 4 to 6; chroma of 3 to 6, or variegated
Texture: loam or sandy loam modified by 50 to 90 percent channers and/or flagstones
Reaction class: moderately acid to neutral.

COMPETING SERIES: These are the Audrey, Gerstle, Kusdry, and Stamp series. Audrey soils have lack schist channers and flagstones. Gerstle and Kusdry soils form stratified silty and sandy alluvium and lack coarse fragments in the control section. Stamp soils are somewhat poorly drained and have a mean annual soil temperature greater than 35 F., 1.7 C.

GEOGRAPHIC SETTING:
Parent material: micaceous loess overlying weathered schist bedrock
Landform: hills
Slopes: 3 to 70 percent
Elevation: 500 to 2800 feet
Climate: cold continental
Mean annual temperature: 23 to 28 degrees F., -5 to -2.2 C.
Mean annual precipitation: 10 to 15 inches, 254 to 381 mm

GEOGRAPHICALLY ASSOCIATED SOILS: These are Brigader and Ester soils. Both of these soils occur on similar landforms and are shallow to weathered bedrock. Ester soils have permanently frozen mineral soils and bedrock.

DRAINAGE AND PERMEABILITY: Moderately well drained, runoff is low to very high; saturated hydraulic conductivity is moderately high to high in the loamy surface horizons and high in the weathered schist.

USE AND VEGETATION: Mostly forested. The principal tree species is black spruce of non-commercial quality. Used for recreation, military training, water supply, and wildlife habitat.

DISTRIBUTION AND EXTENT: MLRA 231 Interior Alaska Highlands. The series is of small extent.

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

SERIES ESTABLISHED: Fort Wainwright Area, Alaska, 2000.

REMARKS: Diagnostic horizons and features recognized in this profile include: Ochric epipedon: 6 to 8 inches, 16 to 19 cm
Cambic horizon: from 8 to 28 inches, 19 to 70 cm
Paralithic contact: 39 inches (100 cm)
Temperature regime: cryic
Particle size control section (weighted average): coarse-loamy from 16 to 33 inches (40 to 100 cm) from mineral soil surface

Manchu soils thaw more slowly in the spring than the similar Steese soils. Some pedons remain frozen until mid-August and may occasionally fail to thaw entirely. Repeated fires and subsequent oxidation of the B horizon could result in conversion of a Manchu soil into a Steese soil.

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National Cooperative Soil Survey
U.S.A.