LOCATION CLATO WAEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, mesic Fluventic Dystroxerepts
TYPICAL PEDON: Clato silt loam - cultivated. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 11 inches; dark yellowish brown (10YR 3/4) silt loam, yellowish brown (10YR 5/4) dry; strong medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many fine and medium roots; many fine tubular pores; moderately acid; clear smooth boundary. (9 to 12 inches thick)
AB--11 to 19 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; strong fine subangular blocky structure; hard, very friable, nonsticky and slightly plastic; many fine and medium roots in the upper 3 inches and common fine roots in the lower 5 inches; many fine interstitial pores; moderately acid; clear smooth boundary. (7 to 10 inches thick)
Bw1--19 to 42 inches; dark yellowish brown (10YR 3/4) silt loam, yellowish brown (10YR 5/4) dry; moderate medium prismatic structure that parts to moderate fine subangular blocky; hard, friable, slightly sticky and slightly plastic; common fine roots; many fine and few coarse tubular pores; moderately acid; diffuse smooth boundary.
Bw2--42 to 69 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; moderate medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few fine roots; many fine and few coarse tubular pores; moderately acid; gradual smooth boundary. (Combined thickness of the Bw horizon is 20 to 40 inches)
C--69 to 80 inches; dark yellowish brown (10YR 3/4) silt loam, yellowish brown (10YR 5/4) dry; common medium distinct dark grayish brown (10YR 4/2) and dark reddish brown (5YR 3/4) mottles, grayish brown (10YR 5/2) and reddish brown (5YR 4/4) dry; massive; hard, friable, slightly sticky and slightly plastic; few fine roots in the upper 3 inches and none below; many fine and few coarse tubular pores; moderately acid.
TYPE LOCATION: Cowlitz County, Washington; approximately 3 miles west of Castle Rock and 180 feet northeast of the intersection of the Hazel Dell Road with the Delameter Road; 940 feet west and 990 feet south of the northeast corner of section 17, T. 9 N., R. 2 W.
RANGE IN CHARACTERISTICS: These soils are usually moist, but are dry in all parts between depths of 7 and 20 inches for 45 to 60 consecutive days. Average annual soil temperature ranges from 50 to 53 degrees F. The particle-size control section is 10 to 18 percent clay and 0 to 15 percent sand coarser than very fine sand. Sandy strata are present below a depth of 40 inches in some pedons. Organic carbon decreases irregularly with depth. The soil ranges from slightly acid to strongly acid throughout.
The A horizon has value of 2 through 4 moist, 5 or 6 dry, and chroma of 4 through 6 moist or dry.
The AB horizon has value of 3 or 4 moist, 5 or 6 dry, and chroma of 3 to 6 moist and dry.
The Bw horizon has value of 3 or 4 moist, 5 or 6 dry, and chroma of 3 to 6 moist and dry. It has an assumed irregular decrease in organic carbon.
COMPETING SERIES: This is the Sedrowoolley series in another family. Sedrowoolley soils have mottles with a chroma of 2 or less within 30 inches of the surface and do not have a Bw horizon with structure.
GEOGRAPHIC SETTING: Clato soils are on floodplains and low terraces at elevations of 30 to 300 feet. Slopes are 0 to 3 percent. These soils formed in alluvial sediments derived from sedimentary and basic volcanic rocks. The climate is characterized by warm, dry summers and cool, wet winters. The average January temperature is 38 degrees F., the average July temperature is 64 degrees F., and the average annual temperature is 51 degrees F. The average growing season (28 degrees F.) is 215 to 240 days. The average annual precipitation is 40 to 60 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Caples, Godfrey, and Newberg soils. Caples and Godfrey soils are fine textured. Newberg soils have a mollic epipedon and are coarse-loamy.
DRAINAGE AND PERMEABILITY: Well-drained; slow runoff; moderate permeability. Some areas of the soils are subject to common flooding unless protected.
USE AND VEGETATION: Used primarily for hay, pasture, and timber production. Clato soils are also used for production of vegetable crops, berries, alfalfa, corn, and small grains. The principal native vegetation is Douglas-fir, western redcedar, red alder, bigleaf maple, and black cottonwood with an understory of vine maple, Oregon-grape, trailing blackberry, salal, western swordfern, and western brackenfern.
DISTRIBUTION AND EXTENT: Southwestern Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Cowlitz County, Washington, 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the surface to 11 inches and a cambic horizon from 11 to 69 inches. The cambic horizon has an assumed irregular decrease in organic carbon with depth based on soil color and stratifications.
Classification revised 1/00 from Fluventic Xerochrepts to Fluventic Dystroxerepts based on amendment to Soil Taxonomy.