LOCATION PUGET WAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, nonacid, mesic Fluvaquentic Endoaquepts
TYPICAL PEDON: Puget silty clay loam - pasture. (Colors are for moist soil unless otherwise noted.)
Al--0 to l inches; very dark grayish brown (2.5Y 3/2) silt loam, moderate thin platy structure; hard, firm, slightly sticky and slightly plastic; many roots; moderately acid (pH 6.0); abrupt smooth boundary. (l to 7 inches thick)
A2--l to 7 inches; dark grayish brown (2.5Y 4/2) silty clay loam, light gray (2.5Y 7/2) dry; common fine prominent dark brown (7.5YR 4/4) redox concentrations; moderate very coarse prismatic structure; hard, firm, moderately sticky and moderately plastic; many roots; moderately acid (pH 6.0); clear smooth boundary. (0 to 7 inches thick)
Bg1--7 to l7 inches; dark grayish brown (2.5Y 5/2) silty clay loam, light olive gray (2.5Y 7/2) dry; common medium prominent strong brown (7.5YR 5/6, 5/8) redox concentrations; moderate medium prismatic structure; hard, firm, moderately sticky and moderately plastic; many roots; slightly acid (pH 6.2); clear smooth boundary. (5 to l2 inches thick)
Bg2--l7 to 25 inches; grayish brown (2.5Y 5/2) silty clay loam, light olive gray (5Y 6/2) dry; many medium prominent yellowish red (5YR 5/8, 4/8) redox concentrations; strong very coarse prismatic structure; very hard, firm, moderately sticky and moderately plastic; common roots; slightly acid (pH 6.4); abrupt smooth boundary. (0 to l2 inches thick)
Bg3--25 to 3l inches; grayish brown (2.5Y 5/2) silty clay loam, light gray (5Y 7/2) dry; many medium prominent dark yellowish brown (l0YR 3/6) and yellowish red (5YR 5/8, 4/6) redox concentrations; moderate medium angular blocky structure; hard, firm, moderately sticky and moderately plastic; few roots; moderately acid (pH 6.0); abrupt wavy boundary. (0 to 6 inches thick)
Bg4--3l to 40 inches; grayish brown (2.5Y 5/2) silty clay loam, light gray (5Y 7/l) dry; common fine prominent strong brown (7.5YR 5/6) and yellowish red (5YR 4/8) redox concentrations; strong very coarse prismatic structure; hard, firm, moderately sticky and moderately plastic; few roots; moderately acid (pH 5.8); clear smooth boundary. (0 to l0 inches thick)
Cg1--40 to 45 inches; greenish gray (5GY 5/l) silty clay loam, light gray (5Y 7/l) and white (5Y 8/l) dry; common fine prominent strong brown (7.5YR 5/6) and brown (7.5YR 4/4) redox concentrations; massive; hard, firm, moderately sticky and moderately plastic; moderately acid (pH 5.8); clear smooth boundary. (0 to 6 inches thick)
Cg2--45 to 60 inches; gray (5Y 5/l) silty clay, light gray (5Y 7/l) dry; few fine prominent yellowish red (5YR 4/8, 5/8) and common medium distinct light olive brown (2.5Y 5/4) redox concentrations; massive; very hard, firm, moderately sticky and moderately plastic, moderately acid (pH 6.0).
TYPE LOCATION: King County, Washington; 1/2 mile southwest of Carnation; 2,640 feet north and 600 feet east of the southwest corner of sec. 2l, T. 25 N., R. 7 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 52 degrees F. The particle-size control section lacks coarse fragments, has less than l5 percent fine and coarser sand, and l8 to 35 percent clay.
The A horizon has hue of 10YR or 2.5Y, value of 3 through 5 moist, 4 through 7 dry and chroma of l or 2 moist and dry. Subhorizons with a value of 3 moist are less than 7 inches thick. It is moderately acid to neutral.
The Bg horizon has hue of l0YR or 2.5Y, value of 4 or 5 moist, 6 or 7 dry and chroma of 2 moist, l or 2 dry. It is silt loam or silty clay loam. Some pedons have thin strata (less than 2 inches thick) or sand or loamy sand. This horizon is slightly acid to very strongly acid.
The Cg horizon has hue of l0YR, 2.5Y, 5Y, or 5GY, value of 4 or 5 moist, 6 or 7 dry and chroma of 0 to 2 moist and dry. It is silt loam, silty clay loam or silty clay and has strata of sand or loamy sand. It is slightly acid to very strongly acid.
COMPETING SERIES: This is the Aetna series. Aetna soils have a buried mollic epipedon that is 10 to 24 inches thick.
GEOGRAPHIC SETTING: The Puget soils are on flood plains at elevations ranging from l0 to 650 feet. They formed in recent alluvium. Slopes are 0 to 3 percent. The soils are in a mild marine climate. Average annual precipitation ranges from 35 to 55 inches, most of which falls as rain during the winter. Snow is infrequent. The average January temperature is about 38 degrees F.; average July temperature is about 64 degrees F.; and mean annual temperature is about 50 degrees F. The frost-free season is about l50 to l90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Briscot, Nooksack, Oridia, Puyallup, and Sultan soils. Briscot soils are coarse-loamy. Nooksack, Puyallup, and Sultan soils have a xeric moisture regime. In addition, Nooksack and Puyallup soils have a mollic epipedon. Oridia soils are coarse-silty.
DRAINAGE AND PERMEABILITY: Poorly drained; slow to ponded runoff; moderately slow permeability. These soils are subject to occasional periods of flooding from December to March. An apparent water table is as high as 1 foot over the surface to 1 foot below the surface at times from November to April unless the soil is drained.
USE AND VEGETATION: Most of the Puget soil has been cleared and drained for use as cropland. Seeded grass pasture, grass-legume hay, oats, and green-chop are the major crops. The natural vegetation is red alder, black cottonwood, western redcedar, and willow with an understory of trailing blackberry, salmonberry, Oregon-grape, western swordfern, Indian plum, hardhack, willow, and rush.
DISTRIBUTION AND EXTENT: The Puget Sound Basin of Western Washington; MLRA 2. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Eastern part of Puget Sound Basin, Reconnaissance, l909.
REMARKS: Laboratory data are available on this series NSSL #S74WA61-7- 341-345. Diagnostic horizons and features recognized in this pedon are an ochric epipedon and a cambic horizon from 17 to 40 inches. The sediments have more than 0.2 percent organic carbon to a depth of 60 inches or more.