LOCATION PORTGRAHAM              AK

Established Series
Rev. DVP/JDW/DLM
02/2022

PORTGRAHAM SERIES

Depth class: moderately deep
Drainage class: well drained
Parent material: silty volcanic ash over glacial till and/or colluvium over bedrock
Landform: mountain slopes
Slopes: range from 15 to 35 percent
Mean annual precipitation: 70 to 120 inches.
Mean annual temperature: 36 to 39 degrees F.

TAXONOMIC CLASS: Medial, mixed Andic Humicryods

TYPICAL PEDON: Portgraham silt loam, on a northeast facing, 32 percent slope under Sitka spruce forest at 300 feet elevation. (When described, the soil was moist throughout).

Oi--0 to 2 inches; very dark brown (10YR 2/2) slightly decomposed plant material; many very fine, fine, and few medium and coarse roots; extremely acid (pH 4.2); abrupt smooth boundary. (1 to 6 inches thick)

E--2 to 4 inches; dark grayish brown (10YR 4/2) silt loam; moderate fine granular structure; very friable, nonsticky, nonplastic; many very fine, fine, medium, and coarse roots; weakly smeary; extremely acid (pH 4.2); abrupt wavy boundary. (1 to 3 inches thick)

Bs--4 to 8 inches; dark brown (7.5YR 3/4) very fine sandy loam; moderate fine granular structure; very friable, nonsticky, nonplastic; many very fine, fine, medium and coarse roots; moderately smeary; moderately acid (pH 5.8); abrupt wavy boundary. (2 to 6 inches thick)

Eb/Bhsb--8 to 11 inches; grayish brown (10YR 5/2) and black (5YR 2.5/1) silt loam; moderate fine granular structure; very friable, nonsticky, nonplastic; many very fine, fine, medium and coarse roots; moderately smeary; strongly acid (pH 5.5); abrupt wavy boundary.(4 to 7 inches thick)

Bhsb--11 to 27 inches; dark reddish brown (5YR 2.5/2) mucky silt loam; moderate fine granular structure; very friable, nonsticky, nonplastic; common very fine, fine, and medium roots; moderately smeary; 10 percent gravel; very strongly acid (pH 4.5); abrupt wavy boundary. (14 to 20 inches thick)

R--27 inches; bedrock.

TYPE LOCATION: Lower Kenai Peninsula Area, Alaska; about 1 mile southwest of Port Graham, 500 feet north and 1400 feet east of the SW corner of section 32, T. 9S., R. 15W., Seward Meridian; USGS Seldovia B-5 quadrangle; lat. 59 degrees 15 minutes 55 seconds N. and long. 151 degrees 50 minutes 56 seconds W.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 37 to 40 degrees F.
Ash mantle thickness: 19 to 34 inches
Solum thickness: 19 to 34 inches
Depth to bedrock: 20 to 40 inches
The pH of the mineral horizons ranges from 4.2 to 5.8.

O horizons:
Matrix color: hue of 7.5YR or 10YR; value of 2 to 4; chroma of 2 to 4
Reaction class: extremely acid or very strongly acid

E and Eb horizons:
Matrix color: hue of 10YR or 2.5Y; value of 4 to 6, and chroma of 2 or 3
Texture: silt loam, very fine sandy loam
Reaction class: extremely acid or strongly acid

Bs and Bsb horizons:
Matrix color: hue of 5YR or 7.5YR, value of 3 or 4, and chroma of 3 or 4
Texture: silt loam, very fine sandy loam with 0 to 14 percent gravel
Total organic carbon content: is less than 6 percent
Reaction class: very strongly acid to moderately acid

Bhs and Bhsb horizons:
Matrix color: hue of 2.5YR or 5YR; value of 2.5 or 3; chroma of 1 to 3
Texture: mucky silt loam, mucky very fine sandy loam modified by 10 to 34 percent gravel and cobbles
Total organic carbon: 6 to 12 percent.
Reaction class: very strongly acid to moderately acid

COMPETING SERIES: These are the Diobsud and Seldovia series. Diobsud soils lack bedrock. Seldovia soils are greater than 40 inches to bedrock.

GEOGRAPHIC SETTING:
Drainage class: well drained
Parent material: silty volcanic ash over glacial till and/or colluvium over bedrock
Landform: mountain slopes
Slopes: range from 15 to 35 percent
Elevations: 20 to 1000 feet.
Climate: is maritime with mild winters and cool summers
Mean January temperature: is about 25 degrees F.
Mean July temperature is 54 degrees F.
Mean annual temperature: 36 to 39 degrees F.
Mean annual precipitation: 70 to 120 inches.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Jakolof, Koyuktolik, Kasitsna, Nanwalek, and Tutka soils. Jakolof soils are more than 40 inches to bedrock and are on stream terraces. Koyuktolik soils are formed in organic matter accumulated in depressions. Kasitsna and Seldovia soils occur on moraines and slopes with thick deposits of glacial till and colluvium. Nanwalek soils are on metastable mountainslopes with thick colluvial deposits. Tutka soils have bedrock within 20 inches and occur on glacially abraded bedrock ridges.

DRAINAGE AND PERMEABILITY: Well drained, medium runoff. Saturated hydraulic conductivity is high.

USE AND VEGETATION: These soils are used for timber production, subsistence, recreation, and wildlife habitat. The native vegetation is Sitka spruce, devils club, alder, salmonberry, fern, and moss.

DISTRIBUTION AND EXTENT: MLRA 223 Cook Inlet Mountains, Kenai Peninsula, Alaska. The series is of small extent.

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

SERIES ESTABLISHED: Lower Kenai Peninsula Area, Alaska. 1998.

REMARKS: Diagnostic horizons and features recognized in this profile include:
Albic horizons 2 to 4 and 8 to 11 inches (E and Eb/Bhsb)
Spodic horizons 4 to 8, 8 to 11, and 11 to 27 inches (Bs. Eb/Bhsb, and Bhsb)
Assumed andic soil properties: from 6 to 27 inches.
Total carbon: 6 to 12 percent in the Bhsb horizon 11 to 27 inches
Temperature regime: cryic

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National Cooperative Soil Survey
U.S.A.