LOCATION LARUSH                  WA

Established Series
Rev. MBM/RJE
06/2011

LARUSH SERIES

The Larush series consists of very deep, well drained soils formed in mixed alluvium. Larush soils are on flood plains and low terraces and have slopes of 0 to 5 percent. The average annual precipitation is about 70 inches and the mean annual temperature is about 49 degrees F.

TAXONOMIC CLASS: Coarse-silty over sandy or sandy-skeletal, isotic over mixed, mesic Vitrandic Humixerepts

TYPICAL PEDON: Larush ashy silt loam, forested (Colors are for moist soil unless otherwise stated)

Oi--0 to 1 inch; slightly decomposed deciduous leaves and twigs.

A1--1 to 5 inches; very dark grayish brown (10YR 3/2) ashy silt loam, grayish brown (10YR 5/2) dry; common fine faint very dark gray (10YR 3/1) organic stains on faces of peds; weak coarse subangular blocky structure; slightly hard, friable, nonsticky and slightly plastic; common very fine roots; common medium and fine tubular pores; strongly acid (pH 5.4); abrupt wavy boundary. (3 to 5 inches thick)

A2--5 to 16 inches; very dark grayish brown (10YR 3/2) ashy silt loam, grayish brown (10YR 5/2) dry; few fine faint very dark gray (10YR 3/1) organic stains on faces of peds; weak coarse subangular blocky structure; soft, very friable, nonsticky and slightly plastic; few fine roots; common medium and fine tubular pores; strongly acid (pH 5.4); abrupt wavy boundary. (6 to 12 inches thick)

Bw--16 to 25 inches; dark grayish brown (2.5Y 4/2) ashy silt loam. light brownish gray (2.5Y 6/2) dry; few fine faint dark grayish brown (10YR 4/2) organic stains on faces of peds; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common medium roots, few medium and fine tubular pores; strongly acid (pH 5.2); abrupt wavy boundary. (6 to 13 inches thick)

2C1--25 to 42 inches; dark grayish brown (2.5Y 4/2) and gray (N 5/0) fine sand, grayish brown (2.5Y 5/2) dry; single grain, loose; few very fine roots; moderately acid (pH 5.8); abrupt wavy boundary. (15 to 30 inches thick)

3C2--42 to 61 inches; dark grayish brown (2.5Y 4/2) silt loam, light brownish gray (2.5Y 6/2) dry; massive; slightly hard, very friable, slightly sticky and slightly plastic; few fine roots; thin strata of fine sand; common fine tubular pores; moderately acid (pH 5.6).

TYPE LOCATION: Skagit County, Washington; about 2 miles southwest of Rockport, Washington; 1,980 feet north and 920 feet east of the southwest corner, sec. 36 T. 35 N., R. 9 E.

RANGE IN CHARACTERISTICS: The umbric epipedon and solum thickness is 15 to 30 inches. These soils are dry in the moisture control section for 45 to 60 consecutive days following summer solstice. The mean annual soil temperature is 53 to 55 degrees F. The upper part of the particle-size control section is 7 to 15 percent clay. Rock fragments range from 0 to 10 percent throughout. Reaction is strongly acid to moderately acid throughout.

The A horizon has hue of 10YR or 2.5Y, value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. Some pedons lack organic stains.

The Bw horizon has hue of 10YR or 2.5Y, value of 3 through 5 moist, 5 or 6 dry, and chroma of 2 or 3 moist and dry. It is silt loam, or very fine sandy loam.

The 2C horizon has hue of 2.5Y or 5Y, value of 5 or 6 dry. It is loamy fine sand, fine sand, or medium sand.

The 3C horizon is stratified sandy, loamy, and silty sediments.

COMPETING SERIES: These are the Puyallup, Ragnar, and Snakelum series in other families. Ragnar and Snakelum soils have irregular decrease in organic matter content with depth. Puyallup soils have a mollic epipedon. Ragnar soils lack an umbric epipedon.

GEOGRAPHIC SETTING: Larush soils formed in alluvium on flood plains and on low terraces above the present flood plain at elevations of 100 to 500 feet. Slopes are 0 to 5 percent. The mean annual precipitation is 60 to 80 inches. Mean January temperature is about 37 degrees F, mean July temperature is about 65 degrees F, and the mean annual temperature is 49 to 53 degrees F. The frost-free season is 180 to 220 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Barneston, Indianola, Greenwater, Pilchuck, and Tokul soils. Barneston soils are sandy-skeletal. Indianola, Greenwater, and Pilchuck soils are in a sandy family. Tokul soils have a cemented horizon.

DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate permeability. These soils are subject to occasional brief periods of flooding from November through April.

USE AND VEGETATION: Soils are used for cropland. Corn, wheat, and pasture are common crops. Native vegetation includes Douglas-fir, western hemlock, western redcedar, red alder and bigleaf maple, with an undergrowth of western brackenfern, geranium, vine maple, trailing blackberry, northern twinflower, and western swordfern.

DISTRIBUTION AND EXTENT: Valleys on the west slopes of the Cascade mountains in northwestern Washington; MLRA 2. The series is of small extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Skagit County area, Washington, 1981.

REMARKS: Diagnostic horizons and other features are:
Umbric epipedon - 1 to 25 inches
Vitrandic properties - 1 to 25 inches

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National Cooperative Soil Survey
U.S.A.