LOCATION IMAK                    AK

Established Series
MPS/SAS
05/2022

IMAK SERIES

Landscape--hills
Landform--hillslopes
Slope--1 to 22 percent
Parent material--mossy organic material over loess
Mean annual precipitation--about 445 mm
Mean annual air temperature--about -3 degrees C
Depth class--very deep (shallow to permafrost)
Drainage class--poorly drained
Soil moisture regime--aquic
Soil temperature regime--gelic
Soil moisture subclass--typic

TAXONOMIC CLASS: Loamy, isotic, euic, subgelic Terric Fibristels

TYPICAL PEDON: Imak peat on a north facing convex, linear footslope on a slope of 22 percent at an elevation of 255 m (The soil was moist from 0 to 60 cm and wet from 60 to 150 cm when described on June 5, 2019.)

Oi--0 to 32 cm; slightly decomposed plant material, reddish yellow (7.5YR 6/6) dry, yellowish red (5YR 4/6) moist; nonsmeary; many very fine roots and common medium and fine roots; very strongly acid (pH 4.8); abrupt wavy boundary

Oa--32 to 60 cm; muck, gray (10YR 6/1) dry, black (7.5YR 2.5/1) moist; nonsmeary; many very fine and fine, and common medium roots; slightly acid (pH 6.3); abrupt smooth boundary

A--60 to 70 cm; silt, dark grayish brown (10YR 4/2) dry, very dark brown (10YR 2/2) moist; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; nonsmeary; many very fine and common fine roots; moderately acid (pH 5.8); gradual wavy boundary

Bw--70 to 80 cm; silt loam, grayish brown (10YR 5/2) dry, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; nonsmeary; many very fine and common fine roots; 5 percent angular fine gravel; slightly acid (pH 6.4); abrupt smooth boundary

Cf--80 to 150 cm; permanently frozen silt loam, olive gray (5Y 5/2) dry, dark olive gray (5Y 3/2) moist; massive; hard, very firm, nonsticky, nonplastic; nonsmeary; 3 percent fine lenticular strong brown (7.5YR 4/6) masses of oxidized iron; 2 percent angular medium gravel; slightly acid (pH 6.5)

TYPE LOCATION: Yukon-Koyukuk Census Area, Alaska, latitude 63.4463840 longitude -160.3843840 degrees, datum WGS84 (Coordinates determined with a GPS unit)

RANGE IN CHARACTERISTICS:
Mean annual soil temperature-- -2 to 0 degrees C
Soil moisture control section--saturated at a depth of between 0 and 25 cm during much of the growing season (aquic moisture regime)
Thickness of organic materials--40 to 90 cm
Cambic horizon--60 to 80 cm
Depth to permafrost contact--60 to 100 cm
Thickness of fibric soil material--20 to 50 cm

Particle Size Control Section:
*Clay--13 to 20 percent
*Total rock fragments--0 to 12 percent
*Sodium fluoride pH--8.4 to 11.6
*Ratio of 1500 kPa water to measured clay--0.6 to 6.0

Oi horizon
Hue--5YR or 10YR
Value--4 to 6 moist, 6 to 8 dry
Chroma--6 to 8
Reaction--4.0 to 5.5
Organic carbon content--80 to 100 percent
Rubbed fiber content--75 to 100 percent
Thickness--20 to 50 cm

Oa horizon
Hue--7.5YR or 10YR
Value--2 or 2.5 moist, 4 or 6 dry
Reaction--5.2 to 6.3
Organic carbon content--75 to 85 percent
Rubbed fiber content--0 to 17 percent
Sodium pyrophosphate color value and chroma-when chroma is 2, value is 5 or less; when chroma is 3, value is 6 or less
Thickness--5 to 50 cm

A horizon
Value--2 to 3 moist, 4 or 5 dry
Chroma--2 or 3
Fine-earth texture--silt, silt loam
Clay--5 to 10 percent
Sand--10 to 30 percent
Organic carbon--5 to 12 percent
Reaction--5.6 to 6.0
Thickness--5 to 15 cm

Bw horizon
Value--3 or 4 moist, 5 or 6 dry
Chroma--1 or 2
Clay--8 to 12 percent
Sand--20 to 35 percent
Organic carbon--3 to 5 percent
Total rock fragment content--0 to 5 percent gravel
Reaction--5.3 to 6.4
Thickness--5 to 20 cm

Cf horizon
Hue--10YR, 2.5Y or 5Y
Value--3 or 4 moist, 5 to 8 dry
Chroma--1 or 2
Clay--8 to 20 percent
Sand--10 to 30 percent
Organic carbon--1 to 3 percent
Total rock fragment content--0 to 12 percent gravel
Reaction--5.6 to 6.6

COMPETING SERIES: None

GEOGRAPHIC SETTING:
*Elevation--10 to 550 m
*Climate--warm, moist summers; cold, dry winters
*Mean annual precipitation--350 to 555 mm
*Mean annual air temperature-- -5 to -1 degrees C
*Frost-free period--55 to 90 days

GEOGRAPHICALLY ASSOCIATED SOILS:
* Pokercreek--no permafrost present, depth to aquic conditions from 22 to 50 cm, acid reaction class; hillslopes

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
*Drainage class--poorly drained
*Saturation during normal years--saturated at the soil surface for two weeks in spring, saturated at a depth between of 0 and 25 cm to the top of the permafrost for much of the growing season
*Saturated hydraulic conductivity (Ksat)--high in the organic surface layer, moderately high in the unfrozen mineral soil layers, very low in the permafrost layer

USE AND VEGETATION:
Use--wildlife habitat, recreation, subsistence
Potential native vegetation--black spruce, kidney lichen, resin birch, black crowberry, marsh Labrador tea, cloudberry, bog blueberry, sedge, Bigelow's sedge, splendid feather moss, Moss, sphagnum, dwarf birch, lingonberry, woodland horsetail, reindeer lichen, Schreber's big red stem moss, reindeer lichen,

DISTRIBUTION AND EXTENT: Yukon-Kuskokwim Highlands, Alaska; MLRA 230; moderate extent

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

SERIES ESTABLISHED: Nulato Hills BLM area, Yukon-Koyukuk Census Area, Alaska; 2021

REMARKS:
Diagnostic horizons and features recognized in this pedon
*Particle-size control section--zone from 60 to 130 cm
*Fibric soil materials--zone from 0 to 32 cm
*Sapric soil materials--zone from 32 to 60 cm
*Cambic horizon--zone from 60 to 80 cm
*Aquic conditions--zone from 0 to 150 cm
*Redoximorphic concentrations--zone from 80 to 150 cm
*Depth to permafrost--80 cm

---

National Cooperative Soil Survey
U.S.A.