LOCATION YOHN AK
Established Series
Rev. MHC/JPM
02/2022
YOHN SERIES
The Yohn series consists of very deep, well drained soils formed in a mantle of interbedded sandy and silty eolian material overlying friable to firm glacial till. Yohn soils are on till plains and hillslopes. Slopes range from 0 to 25 percent. The mean annual temperature is about 35 degrees F. and the mean annual precipitation is about 18 inches.
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive Typic Haplocryods
TYPICAL PEDON: Yohn silt loam - on a southwest facing slope of 9 percent at 100 feet elevation under paper birch and bluejoint reedgrass. (All colors are for moist soil)
Oi--3 inches to 0; dark reddish brown (5YR 3/2) undecomposed grass, moss and forest litter. (1 to 4 inches thick)
E--0 to 2 inches; dark grayish brown (10YR 4/2) silt loam; weak fine granular structure; very friable, nonsticky and nonplastic; many roots of all sizes; strongly acid (pH 5.4); abrupt wavy boundary. (1 to 3 inches thick)
Bs1--2 to 4 inches; yellowish red (5YR 4/6) very fine sandy loam with discontinuous strata and pockets of fine sand and silt; weak medium granular structure; very friable, nonsticky and nonplastic; many roots of all sizes; moderately acid (pH 5.6); clear smooth boundary. (1 to 5 inches thick)
Bs2--4 to 7 inches; strong brown (7.5YR 5/6) very fine sandy loam with discontinuous strata and pockets of fine sand and silt; weak medium granular structure; very friable, nonsticky and nonplastic; common very fine and fine roots; moderately acid (pH 5.6); clear wavy boundary. (0 to 4 inches thick)
BC--7 to 21 inches; dark yellowish brown (10YR 4/6) fine sand and silt occurring as pockets and discontinuous strata; weak medium subangular blocky structure; very friable, nonsticky and nonplastic; common very fine and fine roots; moderately acid (pH 5.8); gradual wavy boundary. (8 to 17 inches thick)
C1--21 to 32 inches; dark yellowish brown (10YR 4/4) and dark brown (10YR 4/3) fine sand and silt occurring as pockets and discontinuous strata; weak coarse subangular blocky structure; very friable, nonsticky and nonplastic; moderately acid (pH 6.0); abrupt wavy boundary. (0 to 10 inches thick)
2C2--32 to 39 inches; dark grayish brown (2.5YR 4/2) very cobbly loam; weak medium subangular blocky structure; friable, sticky and plastic; 25 percent subangular gravel and 15 percent subangular cobble; neutral (pH 7.0); gradual wavy boundary. (5 to 30 inches thick)
2C3--39 to 60 inches; dark grayish brown (2.5YR 4/2) very gravelly loam; weak thick platy structure; firm, sticky and plastic; 30 percent subangular gravel and 10 percent subangular cobble; neutral (pH 7.0).
TYPE LOCATION: Matanuska Valley Area, Alaska, about 8 miles SW of Knik; about 800 feet S. and 300 feet E. of the NW corner of section 1, T.15N., R.4W., Seward Meridian.
RANGE IN CHARACTERISTICS: The solum ranges in thickness from 12 to 23 inches. The weighted average of the control section has more than 15 percent fine sands or coarser and less than 18 percent clay. Coarse fragment content of the lower part of the control section ranges from 35 to 50 percent. Depth to gravelly material ranges from 16 to 37 inches. MAST ranges from 33 to 36 degrees F. Reaction ranges from strongly acid to slightly acid in the solum and is moderately acid to neutral in the substratum.
The E horizon has moist hue of 10YR or 2.5Y, moist value of 4 or 5 and moist chroma of 1 or 2.
The Bs horizons have moist hue from 2.5YR through 7.5YR, moist value from 3 through 5 and moist chroma from 4 through 6. Textures include silt, silt loam, fine sand, fine sandy loam and very fine sandy loam and occur as pockets and discontinuous strata.
The BC and C horizons have moist value of 3 or 4 and moist chroma from 3 through 6. Textures include silt, silt loam, fine sand, fine sandy loam and very fine sandy loam and occur as pockets and discontinuous strata. Coarse fragments are absent in the upper part but increase to 0 to 5 percent cobble and 0 to 5 percent gravel in the lower part of these horizons.
The 2C horizons have moist hue of 10YR or 2.5Y, moist value of 3 or 4 and moist chroma of 2 or 3. Texture is sandy loam or loam. Coarse fragment content ranges from 0 to 20 percent cobble and 25 to 40 percent gravel.
COMPETING SERIES: These are the
Barlow,
Flat Horn,
Hartnit,
Oso,
Stainky(T) and
Timberly series in the same family. Barlow soils have MAST greater than 40 degrees F. Flat Horn soils have less than 5 percent coarse fragments in the control section. Hartnit and Oso soils have bedrock at 20 to 40 inches. Stainky soils are not stratified. Timberly soils have A horizons.
GEOGRAPHIC SETTING: The Yohn soils are on glacial till plains and hillslopes. Slopes range from 0 to 25 percent. The soils formed in a mantle of silty and sandy eolian materials over friable to firm gravelly glacial till. Climate is transitional maritime - continental. Mean annual temperature ranges from 32 to 36 degrees F. Mean annual precipitation ranges from 16 to 22 inches.
DRAINAGE AND PERMEABILITY: Well drained. Slow to medium runoff. Moderate permeability in the loess mantle, moderately slow or slow in the till substrata.
USE AND VEGETATION: Wildlife habitat, agriculture and urban uses. Native vegetation includes paper birch, white spruce, quaking aspen, bluejoint reedgrass and low shrubs.
DISTRIBUTION AND EXTENT: Southcentral Alaska. The series is of moderate extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: WASILLA, ALASKA
SERIES ESTABLISHED: Matanuska-Susitna Area, Alaska, 1996.
REMARKS: Diagnostic features and horizons recognized in this profile include: an albic horizon from 0 to 2 inches; spodic horizons from 2 to 7 inches; weighted average of coarse-loamy from 10 to 40 inches; cryic temperature regime.
National Cooperative Soil Survey
U.S.A.