LOCATION NOOKSACK WAEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, mesic Fluventic Haploxerolls
TYPICAL PEDON: Nooksack silt loam, cultivated. (Colors are for moist soil unless otherwise stated.)
Ap1--0 to 2 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; few fine faint dark yellowish brown (10YR 4/4) mottles; weak thin platy structure; slightly hard, very friable; many roots; slightly acid (pH 6.1); abrupt smooth boundary.
Ap2--2 to 11 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; weak coarse prismatic structure; slightly hard, very friable; common roots; slightly acid (pH 6.1); abrupt smooth boundary. (combined thickness of the A horizon is 10 to 15 inches)
Bw--11 to 29 inches; dark grayish brown (2.5Y 4/2) heavy silt loam, light brownish gray (2.5Y 6/2) dry; weak medium prismatic structure that parts to weak medium subangular blocky structure; hard, friable, slightly sticky, slightly plastic; common roots; moderately acid (pH 6.0); clear smooth boundary. (5 to 21 inches thick)
C1--29 to 42 inches; dark grayish brown (10YR 4/2) and grayish brown (2.5Y 5/2) silt loam and thin lenses of very fine sandy loam, light brownish gray (2.5Y 6/2) dry; massive; slightly hard, very friable; common roots; slightly acid (pH 6.1); clear smooth boundary. (10 to 15 inches thick)
C2--42 to 60 inches; grayish brown (2.5Y 5/2) heavy silt loam, light brownish gray (2.5Y 6/2) dry; massive; hard, friable, sticky, plastic; common roots; moderately acid (pH 6.0).
TYPE LOCATION: About 1 1/2 miles northwest of Fall City, King County, Washington; 2,140 feet north and 1,800 feet east of the southwest corner sec. 4, T.24N., R.7E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is estimated to range from 47 to 52 degrees F. The particle-size control section averages 10 to 15 percent clay, less than 15 percent fine and coarser sand, and less than 1 percent coarse fragments. The soil is slightly acid or moderately acid.
The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. It is weak coarse prismatic and weak thin platy structure.
The Bw horizon has value of 4 or 5 moist, 5 or 6 dry, and chroma of 2 to 4 moist and dry. It is mostly silt loam but some pedons have thin lenses of very fine sandy loam.
The C horizon has value of 4 or 5 moist, 5 or 6 dry, and chroma of 2 to 4 moist and dry and in some pedons is mottled below a depth of 36 inches. The C horizon contains (1/8 to 3/8 inch) lenses of very fine sandy loam in some pedons.
COMPETING SERIES: These are the similar Hampson, Malo, and Newberg series. Hampson soils are frigid. Malo and Newberg soils are coarse- loamy.
GEOGRAPHIC SETTING: Nooksack soils are on flood plains and low terraces from sea level to 500 feet. They formed in silty alluvium. These soils have a marine climate with cool, moist winters and warm, dry summers. The average annual precipitation is 35 to 55 inches. The average July temperature is 64 degrees F.; the average January temperature is 38 degrees F.; and the average temperature is 50 degrees F. The frost free season is about 190 days.
PRINCIPAL ASSOCIATED SOILS: These are the Oridia, Puget, Puyallup, and Sultan soils and the competing Newberg soils. Oridia and Puget soils have an ochric epipedon and aquic moisture regime. Puyallup soils are coarse-loamy over sandy or sandy-skeletal. Sultan soils are fine-silty and have an ochric epipedon.
DRAINAGE AND PERMEABILITY: Moderately well drained; moderate permeability; slow runoff.
USE AND VEGETATION: Used mostly for cropland. Row crop and seeded grass pasture are common crops. Native vegetation is Douglas-fir, western redcedar, and red alder, with an understory of trailing blackberry, salmonberry, western swordfern, Oregon-grape, and red elderberry.
DISTRIBUTION AND EXTENT: Northwestern Washington. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: King County, Washington 1943.
REMARKS: Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the surface to 11 inches, a cambic horizon from 11 to 29 inches, and a particle-size control section from 10 to 40 inches, with an assumed irregular decrease in organic carbon. Organic carbon is assumed to be more than 0.3 percent at 60 inches.