LOCATION SKIPOPA WA
Established Series
Rev. RDH/MBM/RJE
04/2012
SKIPOPA SERIES
The Skipopa series consists of very deep, somewhat poorly drained soils formed in loess over glaciolacustrine sediments. Skipopa soils are on terraces and have slopes of 0 to 15 percent. The mean annual precipitation is about 45 inches, and the mean annual air temperature is about 51 degrees F.
TAXONOMIC CLASS: Fine, isotic, mesic Aquultic Haploxeralfs
TYPICAL PEDON: Skipopa silt loam - on a 5 percent linear slope under an alder and vine maple (Colors are for moist soil unless otherwise stated.)
Oi--0 to 0.5 inch; slightly decomposed plant material consisting of leaves and twigs.
Oa--0.5 to 1 inches; highly decomposed organic matter; abrupt smooth boundary.
A--1 to 3 inches; very dark brown (10YR 2/2) silt loam, brown (7.5YR 4/2) dry; weak fine subangular blocky structure; soft, very friable. slightly sticky and slightly plastic; common very fine and fine and few coarse roots; many very fine and common fine interstitial pores; NaF pH less than 9.4; moderately acid (pH 6.0); clear wavy boundary. (0 to 5 inches thick)
Bw1--3 to 9 inches; dark yellowish brown (10YR 3/4) silt loam, pale brown (10YR 6/3) dry; weak fine subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic and weakly smeary; common fine and very fine and few coarse roots; common very fine and fine interstitial pores; NaF pH 10.5; moderately acid (pH 5.8); clear wavy boundary. (5 to 12 inches thick)
Bw2--9 to 17 inches; dark yellowish brown (10YR 4/4) silt loam, light yellowish brown (10YR 6/4) dry; moderate coarse subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic and weakly smeary; few fine and very few very fine roots; very few very fine and common fine interstitial pores; few fine silt balls; NaF pH 10.5; moderately acid (pH 5.8); clear irregular boundary. (5 to 14 inches thick)
2Bt--17 to 33 inches; gray (5Y 5/1) silty clay, gray (5Y 6/1) dry; common, fine, distinct, strong brown (7.5YR 5/6) mottles; strong very coarse angular blocky structure; hard, firm, sticky, plastic; few thin clay films in pores and on faces of peds; NaF pH 9.8; slightly acid (pH 6.4); gradual wavy boundary. (8 to 37 inches thick)
2Cg--33 to 61 inches; olive (5Y 5/3) and bluish gray (5B 5/1) silty clay, light gray (2.5Y 7/2) and greenish gray (5G 6/1) dry; massive, hard, very firm, sticky, plastic; NaF pH less than 9.4; slightly acid (pH 6.4).
TYPE LOCATION: Skagit County, Washington; about 2 miles south and 1 1/2 miles east of the town of Alger, Washington; 2,000 feet east and 800 feet north of the southwest corner, sec. 21, T. 36 N., R. 4 E.
RANGE IN CHARACTERISTICS: The thickness of the solum ranges from 14 to 24 inches. Mean annual soil temperature is estimated to range from 51 to 53 degrees F. Rock fragment content ranges from 0 to 10 percent in the control section.
The A horizon has hue of 7.5YR or 10YR, value of 2 or 3 moist, 4 to 6 dry, and chroma 2 through 4 moist and dry. Reaction is moderately acid or slightly acid. Some pedons have an E horizon.
The Bw horizon has hue of 7.5YR to 2.5Y, value of 3 to 5 moist, 4 to 7 dry, and chroma 2 through 4 moist and dry. It is silt loam or silty clay loam and averages 12 to 30 percent clay. Reaction is moderately acid or strongly acid.
The 2Bt horizon has hue of 10YR to 5Y, value of 3 to 5, 4 to 7 dry, and chroma of 1 to 3 moist and dry and is mottled. It is silty clay loam, silty, clay, or clay. Clay content is 35 to 60 percent. Reaction is moderately acid to neutral.
The 2Cg horizon has hue of 2.5Y, 5Y, 5G, and 5B, value of 4 through 6 moist, 5 through 8 dry, and chroma 1 through 3 moist and dry. It is silty clay, silty clay loam or clay. Clay content is 35 to 50 percent. Reaction is moderately acid to neutral.
COMPETING SERIES: These are the
Bow,
Kitsap, and
Quilcene series in other families. Bow soils have 15 to 50 percent pebbles in the upper part of the profile. Kitsap soils are in a fine-silty family. Quilcene soils lack an argillic horizon.
GEOGRAPHIC SETTING: Skipopa soils are on lacustrine terraces. Slopes range from 0 to 15 percent. Elevation is 50 to 450 feet. These soils formed in loess underlain by glaciolacustrine sediments. The mean annual precipitation is 30 to 50 inches. Mean January temperature is about 39 degrees F, and mean July temperature is about 62 degrees F. The mean annual air temperature is 49 to 53 degrees F. The frost-free season is 150 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Alderwood,
Barneston,
Bellingham,
Elwell,
Everett,
Gilligan,
Indianola,
Kapowsin,
Labounty,
Larush,
Tokul,
Whatcom, and
Yelm soils. Barneston and Everett soils are sandy-skeletal. Bellingham and Labounty soils have an aquic moisture regime. Alderwood, Kapowsin, Elwell, and Tokul soils have a densic contact. Gilligan soils are well drained and have a coarse-textured substratum. Indianola soils are sandy. Larush soils are coarse-silty over sandy or sandy-skeletal. Whatcom soils are fine-loamy. Yelm soils are moderately well drained and are coarse-loamy.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff. Permeability is moderate above the 2Bt horizon and very slow in the 2Bt horizon and substratum. A perched water table is at 1 to 2 feet from November through May.
USE AND VEGETATION: Mostly used for pasture and woodland. Native vegetation includes Douglas-fir, western redcedar, red alder, and western hemlock with an understory of vine maple, false lily-of-the-valley, western brackenfern, western swordfern, bleeding heart, sweetscented bedstraw, salmonberry, Pacific trillium, and red huckleberry.
DISTRIBUTION AND EXTENT: Northwestern Washington; MLRA 2. This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Skagit County Area, Washington, 1981.
REMARKS: Laboratory number S81WA-073-2. Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the mineral surface to 2 inches, and an argillic horizon from 16 to 32 inches.
National Cooperative Soil Survey
U.S.A.