LOCATION COUSE WA+OREstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, frigid Xeric Argialbolls
TYPICAL PEDON: Couse silt loam - open forest (Colors are for dry soil unless otherwise noted).
Oi & Oe--0 to 0.5 inch; loose and partly decayed grass, pine needles, leaves, and twigs.
A1--0.5 to 4 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; weak thin platy structure parting to weak granular structure; slightly hard, friable, slightly sticky, slightly plastic; common roots; neutral (pH 6.7); clear smooth boundary. (4 to 6 inches thick)
A2--4 to 8 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; weak fine prismatic structure parting to weak medium granular structure; slightly hard, friable, slightly sticky, slightly plastic; common roots; neutral (pH 6.6); clear smooth boundary. (4 to 8 inches thick)
A3--8 to 13 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium prismatic structure parting to subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common roots; common fine pores; thin coatings in pores; neutral (pH 6.6); clear wavy boundary. (4 to 10 inches thick)
AB--13 to 25 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; weak medium prismatic structure parting to moderate medium subangular blocky structure; hard, friable, slightly sticky, slightly plastic; common roots; many fine pores; thin patchy coatings in pores and on ped faces; neutral (pH 6.6); gradual wavy boundary. (8 to 16 inches thick)
BE--25 to 35 inches; mottled grayish brown (10YR 5/2) and light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; few medium distinct dark yellowish brown (10YR 4/4) redox concentrations; weak medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; many fine roots; many pores; dark brown and black stains along vertical faces and in worm casts; slightly acid (pH 6.5); gradual wavy boundary. (6 to 15 inches thick)
E--35 to 42 inches; light gray (10YR 7/2) silt loam, grayish brown (10YR 5/2) moist; few medium distinct mottles of yellowish brown (10YR 5/6); very weak medium prismatic structure parting to weak fine subangular blocky structure; slightly hard, friable; few roots; common very fine pores; slightly acid (pH 6.3); abrupt wavy boundary. (2 to 8 inches thick)
Btb--42 to 70 inches; brown (10YR 4/3) and dark grayish brown (10YR 4/2) silty clay loam, pale brown (10YR 6/3) and grayish brown (10YR 5/2) dry; strong medium prismatic parting to moderate fine blocky structure; very hard, firm, moderately sticky, moderately plastic; very dark brown (10YR 2/2) and few light brownish gray (10YR 6/2) specks on faces of peds; continuous clay films on ped faces and in pores; neutral (pH 6.6); gradual wavy boundary. (20 to 40 inches thick)
2R--70 inches; basalt.
TYPE LOCATION: Walla Walla County, Washington; along Jasper Mountain Road, NE1/4NE1/4 sec. 26, T. 8 N., R. 38 E.
RANGE IN CHARACTERISTICS: Depth to the top of argillic horizon is more than 40 inches. The mean annual soil temperature ranges from 45 to 47 degrees F. These soils are usually moist, but are dry between 4 and 12 inches for 45 to 60 consecutive days during summer and fall. The mollic epipedon is 20 to 30 inches thick.
The A horizons have value of 2 or 3 moist and 4 or 5 dry. Reaction is moderately acid to neutral.
The AB horizon has more than 1 percent organic matter in the upper part. Reaction is moderately acid to neutral.
The E horizon has value of 4 to 6 moist, 6 to 8 dry, and chroma of 1 or 2. The horizon has mottles with chroma of more than 3. Reaction is slightly acid or neutral.
The Btb horizon has hue of 7.5YR or 10YR value of 4 or 5 dry, 3 or 4 moist. It is silt loam or silty clay loam. Reaction is neutral or slightly alkaline.
COMPETING SERIES: There are no competing series. The Cloverland series in another family have an argillic horizon within 40 inches of the surface and are in a fine-silty family.
GEOGRAPHIC SETTING: Couse soils are on mountain plateaus and benches and have slopes of 0 to 60 percent. These soils formed in loess of 2 or more ages and a minor influence of volcanic ash and basalt. Elevations range from 3,200 to 4,000 feet. These soils are in a climate with warm, dry summers and cool, moist winters. The average annual precipitation ranges from 24 to 30 inches. The mean January temperature is about 28 degrees F, and the mean July temperature is about 64 degrees F. The mean annual temperature is about 44 degrees F. Frost-free season is 90 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Larkin, Palouse, Tolo, and Tucannon series. Larkin, Palouse, and Tucannon soils are mesic. Tolo soils are more than 60 percent volcanic ash in the upper part of the soil.
DRAINAGE AND PERMEABILITY: Moderately well drained. Runoff is slow to rapid. Permeability is moderate above the Btb horizon and very slow in the Btb horizon.
USE AND VEGETATION: Mostly used for cropland. Small grain, peas, grass, legumes and hay are common crops. In uncultivated areas the principal vegetation is ponderosa pine, a few Douglas-fir and grand fir, and understory mainly of spirea, common snowberry, creambush oceanspray, and grasses.
DISTRIBUTION AND EXTENT: Southeastern Washington and northeastern Oregon. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Columbia County, Washington, 1938.
REMARKS: Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the mineral surface to 25 inches, an albic horizon from 35 to 42 inches, and an argillic horizon from 42 to 70 inches. Because the argillic horizon lies wholly below 40 inches, the particle-size control section is from 10 to 40 inches in this soil. Laboratory data are available on 2 pedons from Columbia County, Washington, Lab #S58WA-7-2-1-11 and S58WA-7-3-1-10.