LOCATION YAKOBI AK
Established Series
CSC/JMD/JJL/JPM
02/2022
YAKOBI SERIES
The Yakobi series consists of shallow, somewhat poorly drained soils formed in glacial till overlying dense compact till. Yakobi soils are on mountainslopes, hillslopes, and till plains. Slopes range from 5 to 75 percent Mean annual temperature is about 46 degrees F., and the mean annual percipitation is in excess of 60 inches.
TAXONOMIC CLASS: Loamy, mixed, superactive, shallow Typic Humicryods
TYPICAL PEDON: Yakobi mucky silt loam - on a southeast facing slope of 44 percent at 425 feet elevation on a concave hillslope under conifer vegetation. (all colors are for moist soil)
Oi--7 to 5 inches; forest litter and mosses; common very fine, fine, medium and coarse roots; extremely acid (pH 4.0); clear smooth boundary. (0 to 8 inches thick)
Oa--5 to 0 inches: black (5YR 2.5/1) muck; common very fine, fine, medium and coarse roots; extremely acid (pH 4.0); abrupt smooth boundary. (0 to 8 inches thick)
Bh--0 to 1 inch; black (5YR 2.5/1) mucky silt loam; weak fine subangular blocky structure; friable; slightly sticky and slightly plastic; common very fine and fine roots; extremely acid (pH 4.0); abrupt smooth boundary. (0 to 6 inches thick)
Bs--1 to 9 inches; dark brown (7.5YR 4/4) silt loam; weak medium subangular blocky structure; friable; slightly sticky and slightly plastic; few fine roots; 5 percent gravel; strongly acid (pH 5.5); gradual smooth boundary. (0 to 11 inches thick)
BC--9 to 18 inches; olive brown (2.5Y 4/4) gravelly loam; massive; friable; slightly sticky and slightly plastic; common fine distinct brown (7.5YR 5/2) and dark yellowish brown (10YR 3/4) mottles; 15 percent gravel; strongly acid (pH 5.5); abrupt smooth boundary. (0 to 14 inches thick)
Cd--18 to 60 inches; greenish gray (5GY 5/1) very gravelly sandy loam; massive; extremely firm; nonsticky and nonplastic; common fine distinct dark reddish brown (5YR 3/4) mottles; 35 percent gravel; moderately acid (pH 6.0).
TYPE LOCATION: Kadashan, Chatham Area, Alaska. SW 1/4, SW 1/4, Section 17, T.48S.,R.63E., Copper River Meridian.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 38 to 42 degrees F. The thickness of the solum and depth to the compact till layer ranges from 14 to 20 inches. Reaction increases with depth, ranging from extremely acid to slightly acid. Coarse fragment content in the control section ranges from 0 to 30 percent gravel. An Oe horizon is present in some pedons. The combined thickness of the O horizons ranges from 2 to 8 inches.
An E horizon up to 3 inches thick may be present in 50 percent opr more of each pedon. Hue is 7.5YR or 10YR; value ranges from 5 to 8; and chroma is 1 or 2. Texture is commonly silt loam but ranges to include sandy loam. The coarse fragment content ranges from 0 to 30 percent. The Bh horizon has hue from 2.5YR to 10YR; value of 2.5 or 2 and chroma of 0 or 1. Texture is commonly sandy loam but the range includes loam or silt loam. Coarse fragment content ranges from 0 to 35 percent gravel.
A Bhs horizon up to 14 inches thick is present in some pedons. The Bhs horizon has hue from 2.5YR to 10YR; value from 2 to 3; and chroma from 1 to 3. Texture is commonly silt loam but ranges to include sandy loam or loam. The coarse fragment content ranges from 0 to 35 percent gravel.
The Bs horizon has hue from 5YR to 10YR; value of 3 or 4, and chroma from 3 to 6. Mottles may be present in the lower part of the Bs horizon. Texture is commonly silt loam but ranges to include sandy loam or loam. The coarse fragment content ranghes from 0 to 35 percent gravel.
The BC horizon has hue of 10YR or 2.5Y; value from 3 to 5 and chroma from 2 to 4. Texture is commonly sandy loam but ranges to include loam or silt loam. The coarse fragment content ranges from 15 to 35 percent gravel. Fine, prominent, dark brown mottles are present in some pedons.
The Cd horizons have hue from 10YR to 5GY; value from 2 to 5 and chroma from 1 to 3. Texture is commonly sandy loam but ranges to include silt loam or loam. The coarse fragment content ranges from 35 to 65 percent gravel.
COMPETING SERIES: These are the
Tokeen,
Ulloa, and
Vixen series in the same subgroup. These soils do not have dense compact till within 20 inches.
GEOGRAPHIC SETTING: Yakobi soils are on mountainslopes and hillslopes. The soils formed in glacial till overlying compact glacial till. The climate is humid maritime with mean annual precipitation ranges from 60 to 220 inches. The mean summer temperature is about 57 degrees F. Elevation ranges from 0 to 1500 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the
Karta and
Nakwasina soils. Karta soils are on similar landforms but are well drained. Nakwasina soils have a histic epipedon, are poorly drained and are in swales and depressions.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Moderate permeability above the compact till layer, very slowly permeable in the compact till layer. Runoff is very slow.
USE AND VEGETATION: The Yakobi soils are used for wildlife habitat, recreation, watershed protection, and timber production. The overstory vegetation is dominantly western hemlock with some yellow cedar. The understory vegitation is dominantly blueberry with some rusty menziesia.
DISTRIBUTION AND EXTENT: Southeast Alaska. The series is of moderate extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: WASILLA, ALASKA
SERIES ESTABLISHED: Chatham Area, Tongass National Forest, Alaska, 1992.
REMARKS: Diagnostic horizons and features recognized in this profile include: a spodic horizon from 0 to 9 inches with assumed organic carbon content of greater than 6 percent in the upper 4 inches; a cryic temperature regime; weighted average particle size of coarse-loamy from 9 to 18 inches; dense compact till at 18 inches.
ADDITIONAL DATA: NSSL laboratory data from similiar soils in the area show greater than 6 percent organic carbon in the upper spodic horizons.
National Cooperative Soil Survey
U.S.A.