LOCATION KROTO AK

Established Series
Rev. KMO-JPM
05/2022

KROTO SERIES

The Kroto series consists of very deep, well drained soils formed in a thin mantle of ash-influenced loess overlying firm glacial till. Kroto soils are on moraines, hills, and mountain footslopes. Slopes range from 0 to 45 percent. Mean annual temperature is about 34 degrees F., and the average annual precipitation is about 26 inches.

TAXONOMIC CLASS: Medial over loamy, mixed, superactive Andic Haplocryods

TYPICAL PEDON: Kroto silt loam - on a northeast facing slope of 4 percent under forest vegetation. (All colors are for moist soil)

Oe--3 inches to 0; mat of roots and moderately decomposed forest litter. (1 to 3 inches thick)

E--0 to 2 inches; gray (10YR 6/1) silt loam; weak fine granular structure; very friable; nonsticky and nonplastic; many fine and medium roots; very strongly acid; abrupt wavy boundary. (1 to 3 inches thick)

Bhs--2 to 4 inches; dark reddish brown (5YR 3/3) silt loam; weak fine granular structure; very friable, nonsticky and nonplastic; many fine and medium roots; strongly acid; clear smooth boundary.

Bs1--4 to 6 inches; strong brown (7.5YR 5/6) silt loam; weak fine subangular blocky structure; very friable, nonsticky and nonplastic; few fine distinct patches of dark reddish brown (5YR 3/4); many fine and medium roots; strongly acid; gradual wavy boundary.

Bs2--6 to 9 inches; yellowish brown (10YR 5/6) silt loam; weak fine subangular blocky structure; very friable, nonsticky and nonplastic; many fine and medium roots; strongly acid; clear smooth boundary.

Bs3--9 to 12 inches; dark yellowish brown (10YR 4/4) silt loam; weak fine subangular blocky structure; very friable, nonsticky and nonplastic; common fine and medium roots; strongly acid; abrupt smooth boundary. (Combined B horizons: 6 to 17 inches thick)

Eb--12 to 14 inches; grayish brown (2.5Y 5/2) silt loam; weak fine subangular blocky structure; very friable, nonsticky and nonplastic; common fine and medium roots; strongly acid; abrupt wavy boundary. (1 to 3 inches thick)

Bsb--14 to 19 inches; brown (7.5YR 4/4) silt loam; weak fine subangular blocky structure; very friable, nonsticky and nonplastic; few fine roots; strongly acid; clear smooth boundary. (2 to 5 inches thick)

2C--19 to 60 inches; olive brown (2.5Y 4/4) gravelly silt loam; massive; firm; 15 percent gravel, 5 percent cobble; strongly acid.

TYPE LOCATION: Yentna Area, Alaska; in the southwest quarter of the southeast quarter of section 27, T.26N., R.7W., Seward Meridian.

RANGE IN CHARACTERISTICS: The pedons have a bisequal sola. The combined sola ranges from 14 to 20 inches thick. The upper 4 inches of the spodic horizon has less than 6 percent organic carbon. The loess mantle ranges from 10 to 20 inches in thickness over the firm, glacial till substratum. The sola is usually completely developed in the loess mantle, but, in some pedons, extends into the underlying till material. The exchange complex of the sola is dominated by amorphous material. Reaction ranges from extremely acid to strongly acid.

The A horizon, when present, has hue from 7.5YR to 2.5Y; value moist of 2 or 3; and chroma moist of 1 or 2.

The E horizon has hue from 7.5YR to 2.5Y; value moist from 4 to 6; and chroma moist of 1 or 2. Texture is silt loam or very fine sandy loam.

The B horizons have hue from 5YR to 10YR; value moist from 3 to 5; and chroma moist from 1 to 6. Texture is silt loam or very fine sandy loam. The buried solum is similar to the surface solum in color and texture.

C horizons, below the buried solum, are present in some pedons

The 2C horizon is massive, firm, loam or silt loam. Coarse fragment content ranges from 5 to 35 percent with 5 to 30 percent gravel and 0 to 15 percent cobbles.

COMPETING SERIES: These are the Boulder Point, Cohoe, Darling, Flat Horn, Kenai, Strandline, Swanson(T), Tuomi(T), and Whitsol series of the same family, and the Chulitna, Chuit, Kashwitna, Nancy, and Puntilla series. Boulder Point, Darling, Flat Horn, Tuomi(T), and Whitsol soils have loose or friable substratums. Cohoe soils have strata of sand and sandy loam in the control section. Kenai soils have greater than 18 percent clay in the substratum. Strandline and Swanson(T) soils have loess mantles thicker than 20 inches. Chuit and Puntilla soils have more than 6 percent organic carbon in the upper part of the spodic horizon. Chulitna, Kashwitna, and Nancy soils are sandy or sandy-skeletal in the lower part of the control section.

GEOGRAPHIC SETTING: Kroto soils are on moraines and on the footslopes of hills and mountains that have been subject to glacial deposition. Slopes range from 0 to 45 percent. The soils formed in a thin mantle of loess overlying massive, firm glacial till. The loess contains varying amounts of volcanic ash. The mean annual temperature ranges from 32 to 36 degrees F. The average annual precipitation ranges from 20 to 34 inches.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing Puntilla and Strandline soils, and the Spenard soil. Spenard soils have loess mantles thicker than 20 inches and a seasonal high water table.

DRAINAGE AND PERMEABILITY: Well drained. Slow to rapid runoff. Moderate permeability in the loess mantle and moderately slow in the till substratum.

USE AND VEGETATION: Kroto soils are mostly forested. The dominant trees are paper birch and white spruce. The understory consists of bluejoint grass, alder, and forbs.

DISTRIBUTION AND EXTENT: South-central Alaska. The series is of moderate extent.

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

SERIES ESTABLISHED: Yentna Area Alaska, 1986.

REMARKS: Diagnostic horizons and features recognized in this pedon include: spodic horizons from 2 to 6 inches and buried spodic from 14 to 19 inches; cryic temperature regime; amorphous material dominant in the exchange complex from 0 to 19 inches; loamy particle size from 19 to 60 inches.

National Cooperative Soil Survey
U.S.A.