LOCATION PATIT CREEK        WA
Established Series
Rev. RFM/RJE
12/1999

PATIT CREEK SERIES


The Patit Creek Series consists of deep, well drained soils formed in recent alluvium on bottomlands. Slopes are 0 to 3 percent. The average annual precipitation is about 20 inches. The mean annual temperature is about 50 degrees F.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Cumulic Haploxerolls

TYPICAL PEDON: Patit Creek silt loam - cultivated. (Colors for moist conditions unless otherwise noted)

Ap--0 to 6 inches; very dark brown (l0YR 2/2) silt loam, dark grayish brown (l0YR 4/2) dry; moderate fine granular structure; slightly hard, friable, slightly sticky, slightly plastic; many fine and very fine roots; some earthworm channels and casts; neutral (pH 6.8); abrupt smooth boundary. (5 to 8 inches thick)

A2--6 to l2 inches; very dark brown (l0YR 2/2) silt loam, dark grayish brown (l0YR 4/2) dry; moderate medium and fine granular structure; slightly hard, friable, sticky, plastic; many fine and very fine roots; few fine tubular pores; some earthworm channels and casts; about 5 percent pebbles neutral (pH 6.8); clear wavy boundary. (4 to l8 inches thick)

A3--l2 to 24 inches; very dark brown (l0YR 2/2) silt loam, dark grayish brown (l0YR 4/2) dry; weak medium prismatic structure; hard, friable, sticky, plastic; many fine and very fine roots; few fine tubular pores; some earthworm channels and casts; few faint, fine mottles; very few thin patchy clay films on peds; about 5 percent pebbles; neutral (pH 6.8); clear wavy boundary. (0 to l5 inches)

A4--24 to 36 inches; very dark brown (l0YR 2/2) silt loam, dark grayish brown (l0YR 4/2) dry; massive; slightly hard, friable, sticky, plastic; few very fine roots; few fine tubular pores; some earthworm channels and casts; about 5 percent pebbles; neutral (pH 6.8); clear wavy boundary. (0 to 24 inches thick)

2C--36 to 66 inches; dark brown (l0YR 3/3) extremely gravelly sandy loam, brown (l0YR 5/3) dry; massive; soft, friable, nonsticky, nonplastic; few very fine roots; few faint fine mottles; about 65 percent pebbles, 5 percent cobbles; neutral (pH 6.8)

TYPE LOCATION: Columbia County, Washington - 1/4 mile west of Dumas, SE1/4NW1/4, sec. 4, T. 9 N., R. 38 E.

RANGE IN CHARACTERISTICS: Depth to the 2C horizon is 20 to 40 inches. Mean annual soil temperature is 50 to 52 degrees F. These soils are neutral or mildly alkaline throughout. These soils are dry for 60 to 75 consecutive days in the moisture control section following summer solstice. Percent clay in the soil above the 2C horizon ranges from 8 to 15 and percent of fragments coarser than very fine sand ranges from 15 to 50.

The A horizon has value of 4 or 5 dry, 2 or 3 moist. It is loam, silt loam, gravelly loam, or cobbly loam.

The 2C horizon has value of 3 or 4 moist, 5 or 6 dry, and chroma of 2 to 4. It is very gravelly, very cobbly or extremely gravelly.

COMPETING SERIES: These are the Endersby, Evans, Leavenworth, Narcisse, Pleasant View, and Redola series. Endersby soils are dry for more than 90 consecutive days. Evans and Leavenworth soils lack rock fragments in the particle-size control section. Narcisse soils have less than 20 percent rock fragments throughout and have mottles in the lower part of the particle-size control section. Pleasant View soils have a Ck horizon within 40 inches of the surface. Redola soils are slightly calcareous to strongly calcareous throughout.

GEOGRAPHIC SETTING: Patit Creek soils are on bottomlands along streams at an elevation of 1,200 to 2,800 feet. The soils formed in alluvium derived mainly from loess, mixed with basaltic material. Annual precipitation is 18 to 24 inches. Summers are warm and dry, and winters are cold and wet. Average January temperature is about 30 degrees F; average July temperature is about 7l degrees F; mean annual temperature is about 50 degrees F. Frost-free season is l20 to l40 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These include Athena, Gwin, Kuhl, Mondovi, and Palouse. Athena, Mondovi, and Palouse soils lack a contrasting substratum within 40 inches, and Gwin and Kuhl soils are underlain by bedrock between l0 and 20 inches.

DRAINAGE AND PERMEABILITY: Well drained; permeability is moderate above the 2C horizon and moderately rapid in the 2C horizon. Runoff ranges from very slow to slow.

USE AND VEGETATION: Used for cropland and grazed woodland. Crops include asparagus, corn for silage, grasses, legumes, and orchards--mostly irrigated. Native vegetation is bluebunch wheatgrass, Sandberg bluegrass, basin wildrye, black hawthorn, rose, and scattered Douglas-fir, ponderosa pine, black cottonwood, and alder.

DISTRIBUTION AND EXTENT: Eastern Washington, eastern Oregon, and possibly northern Idaho. The series is of small extent.

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

SERIES EFSTABLISHED Columbia County, Washington, l938.

REMARKS: Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the surface to 36 inches, with an assumed irregular decrease in organic carbon with depth, and a lithologic discontinuity to extremely gravelly sandy loam at 36 inches.


National Cooperative Soil Survey
U.S.A.