LOCATION PETROKOV                AK

Established Series
Rev. MHC/DLM
02/2022

PETROKOV SERIES

Depth class: very deep
Drainage class: somewhat excessively drained
Landforms: mountains and outwash plains
Parent material: silty eolian deposits over gravelly outwash
Elevation: 2,667 to 3,812 feet (813 to 1,162 m)
Slope: 6 to 65 percent
Annual precipitation: 31 to 37 inches (776 to 940 mm)
Annual temperature: 25 degrees F (-4 degrees C)
Frost-free period: 50 to 70 days

TAXONOMIC CLASS:

TYPICAL PEDON: Petrokov silt loam - on a slope of 28 percent under shrub birch-dwarf ericaceous scrub mosaic. (All colors are for moist soil)

Oi--0 to 2 inches (0 to 5 cm); black (10YR 2/1) slightly decomposed plant material; many very fine, fine, and medium roots; very strongly acid (pH 4.5); clear wavy boundary.

A--2 to 5inches (5 to 13 cm); very dark brown (10YR 2/2) silt loam; weak medium granular structure; very friable, nonsticky and nonplastic; many very fine, fine, and medium roots; 2 percent gravel; strongly acid (pH 5.3); clear wavy boundary.

2Bw1--5 to 13 inches (13 to 33 cm); brown (7.5YR 4/4) and dark reddish brown (5YR 3/4) cobbly sandy loam; weak medium subangular blocky structure; very friable, nonsticky and nonplastic; many very fine and fine roots; 15 percent gravel, 15 percent cobbles; strongly acid (pH 5.4); gradual wavy boundary.

2Bw2--13 to 23 inches (33 to 58 cm); dark yellowish brown (10YR 4/4) extremely cobbly coarse sand; single grain; loose, nonsticky and nonplastic; many very fine and fine roots; 40 percent gravel, 25 percent cobbles; moderately acid (pH 5.8); diffuse wavy boundary.

2C--23 to 60 inches (58 to 152 cm); dark brown (10YR 3/3) extremely cobbly loamy coarse sand; single grain; loose, nonsticky and nonplastic; few very fine and fine roots; 40 percent gravel, 25 percent cobbles; moderately acid (pH 5.8).

TYPE LOCATION: Delta River Area, Alaska; about 7.2 miles east of Juneau Falls UTM coordinates: Zone 6, Easting 559124, Northing 7008774.

RANGE IN CHARACTERISTICS:

Soil moisture class: udic
Mean summer soil temperature: 36 to 39 degrees F. (2 to 4 degrees C)
Average annual soil temperature: 28 to 29 degrees F (-2.5 to -1.5 degrees C)
Depth to strongly contrasting textural stratification: 2 to 6 inches (5 to 15 cm)

Oi horizon:
Colorhue of 5YR to 10YR; value of 2 or 3; chroma of 1 or 2
Organic matter content65 to 90 percent

A horizon:
Colorvalue of 2 or 3; chroma of 2 or 3
Clay content0 to 10 percent
Silt content55 to 75 percent
Sand content15 to 35 percent
Organic matter content4 to 10 percent
Rock fragments0 to 5 percent rounded strongly cemented gravel
Reactionvery strongly acid or strongly acid

2Bw horizon:
Colorhue of 7.5YR to 2.5Y; value of 3 to 5; chroma of 3 to 8
Textureextremely cobbly coarse sand, very gravelly coarse sand or extremely gravelly coarse sand
Clay content0 to 5 percent
Silt content0 to 15 percent
Sand content80 to 95 percent
Organic matter content0 to 2 percent
Rock fragments15 to 60 percent rounded very strongly cemented gravel; 5 to 30 percent rounded very strongly cemented cobbles
Reactionvery strongly acid to moderately acid

2C horizon:
Colorhue of 10YR or 2.5Y; value of 3 to 5; chroma of 2 to 4
Textureextremely cobbly loamy coarse sand, very gravelly loamy coarse sand, extremely gravelly coarse sand, cobbly sandy loam
Clay content0 to 5 percent
Silt content0 to 15 percent
Sand content80 to 95 percent
Organic matter content0 to 0 percent
Rock fragments30 to 60 percent rounded very strongly cemented gravel; 5 to 30 percent rounded very strongly cemented cobbles
Reactionstrongly acid or moderately acid

COMPETING SERIES: There are no competing series in this classification.

GEOGRAPHIC SETTING:
Landforms: mountains and outwash plains
Parent material: silty eolian deposits over gravelly outwash
Elevation: 2,667 to 3,812 feet (813 to 1,162 m)
Slope: 6 to 65 percent
Annual precipitation: 31 to 37 inches (776 to 940 mm)
Annual temperature: 25 degrees F (-4 degrees C)
Frost-free period: 50 to 70 days

GEOGRAPHICALLY ASSOCIATED SOILS: These include Basaltlake and Castnot soils. Basaltlake and Castnot soils are well drained, very deep, and occur on mountains.

DRAINAGE AND PERMEABILITY: Somewhat excessively drained, high runoff. Saturated hydraulic conductivity is moderately high to high in the upper part of the solum and high to very high in the lower part of the profiles.

USE AND VEGETATION: Used for wildlife habitat and recreation. Native vegetation is shrub birch-dwarf ericaceous scrub mosaic.

DISTRIBUTION AND EXTENT: MLRA 228, Interior Alaska Mountains, Alaska. The series is of small extent.

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

SERIES ESTABLISHED: Delta River Area, Alaska, 2005

REMARKS: Diagnostic features and horizons recognized in this profile include:
Cambic horizon: 5 to 25 inches. (2Bw1 and 2Bw2 horizons)
Lithologic discontinuity: At the upper boundary of 2Bw1 horizon
Sandy-skeletal particle size control section (weighted average): 10 to 40 inches below mineral soil surface
Temperature regime: cryic
Temperature class: subgelic

ADDITIONAL DATA:

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National Cooperative Soil Survey
U.S.A.