LOCATION KEWACH WAEstablished Series
TAXONOMIC CLASS: Fine, isotic, frigid Vitrandic Palexeralfs
TYPICAL PEDON: Kewach silt loam - on a 5 percent west-facing slope at 1,890 feet elevation under a mixed Douglas-fir and western larch canopy. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 2 inches; slightly decomposed needles, twigs, and bark.
A--2 to 6 inches; pale brown (10YR 6/3) silt loam, dark brown (10YR 3/3) moist; moderate very fine and fine subangular blocky structure; soft, friable, slightly sticky and nonplastic; many very fine and common fine and medium roots; neutral (pH 6.8); clear smooth boundary. (2 to 7 inches thick)
E--6 to 12 inches; pale brown (10YR 6/3) silt loam, brown (10YR 4/3) moist; moderate fine angular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, fine and medium and few coarse roots; neutral (pH 6.6); abrupt wavy boundary. (0 to 7 inches)
B/E--12 to 18 inches; B part is very pale brown (10YR 7/3) silt loam, yellowish brown (10YR 5/4) moist, E part is light gray (10YR 7/2) silt loam, pale brown (10YR 6/3) moist; moderate coarse angular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine, common fine and few medium roots; neutral (pH 6.6); clear wavy boundary. (5 to 10 inches thick)
Bt/E--18 to 31 inches; Bt part is pale yellow (2.5Y 7/4) silt loam, light olive brown (2.5Y 5/4) moist, E part is light gray (2.5Y 7/2) silt loam, light olive brown (2.5Y 5/4) moist; moderate coarse angular blocky structure; hard, friable, moderately sticky and moderately plastic; many very fine and few fine and medium roots; few faint clay films on faces of peds; neutral (pH 6.6); gradual wavy boundary. (4 to 13 inches thick)
Bt--31 to 38 inches; brownish yellow (10YR 6/6) silty clay loam, dark yellowish brown (10YR 4/4) moist; moderate coarse platy structure; very hard, firm, moderately sticky and moderately plastic; common very fine, fine and few medium and coarse roots; common faint clay films on faces of peds; neutral (pH 7.2); abrupt wavy boundary. (5 to 10 inches thick)
Btk--38 to 44 inches; light yellowish brown (2.5Y 6/4) silty clay loam, light olive brown (2.5Y 5/4) moist; moderate coarse angular blocky structure and finely laminated; very hard, very firm, moderately sticky and moderately plastic; few fine roots; many faint clay films on faces of peds; slightly effervescent; neutral (pH 7.2); clear smooth boundary. (6 to 13 inches thick)
Bk--44 to 60 inches; light gray (5Y 7/2) silty clay loam, olive (5Y 5/4) moist; laminated; hard, friable, moderately sticky and moderately plastic; few fine roots; slightly effervescent; slightly alkaline (pH 7.8).
TYPE LOCATION: Colville Indian Reservation; Ferry County, Washington; 1,550 feet south and 1,000 feet west of the northeast corner of sec. 32, T. 30 N., R. 35 E., W.M.
RANGE IN CHARACTERISTICS: The mean annual soil temperature at a depth of 20 inches is 44 to 46 degrees F. These soils are usually moist but are dry in all parts between depths of 4 and 12 inches for 60 to 75 consecutive days following the summer solstice. The upper 7 to 14 inches has an estimated moist bulk density of 1.20 to 1.30 g/cc, volcanic glass content of 5 to 20 percent, acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of 0.4 to 1.0 percent, and 15-bar water retention of 5 to 10 percent for air dried samples. The argillic horizon averages 35 to 45 percent clay. Organic carbon to 4 inches is estimated to be 1 to 2 percent.
The A horizon has value of 5 or 6 dry, 3 or 4 moist, and chroma of 2 or 3 moist or dry. Reaction is slightly acid or neutral.
The E horizon, when present, has value of 6 or 7 dry, and chroma of 2 or 3 moist or dry. Reaction is slightly acid or neutral.
The B/E and Bt/E horizon have value of 6 or 7 dry, 4 through 6 moist, and chroma of 2 through 4 moist or dry. It is silt loam or silty clay loam. Reaction is neutral or slightly alkaline.
The Bt horizon has hue of 10YR, 2.5Y, or 5Y, value of 6 through 8 dry, 3 through 6 moist, and chroma of 2 through 4 dry or moist. It is silty clay or silty clay loam. Reaction is neutral or slightly alkaline.
The Bk horizon has hue of 10YR, 2.5Y or 5Y, value of 6 through 8 dry, 4 through 6 moist, and chroma of 2 through 4 moist or dry. It is silty clay loam, silty clay, or silt loam. Reaction is slightly alkaline or moderately alkaline.
COMPETING SERIES: This is the Bearrun series. Bearrun soils do not have horizons of secondary calcium carbonate accumulation.
GEOGRAPHIC SETTING: Kewach soils are on terraces and terrace escarpments. These soils formed in glacial lake sediments with a component of loess and volcanic ash. Slopes are 0 to 50 percent. Elevation ranges from 1,300 to 2,000 feet. The climate is characterized by warm, dry summers and cold, moist winters. The average annual precipitation is 15 to 18 inches. The mean January temperature is about 24 degrees F, mean July temperature is about 65 degrees F, and the mean annual temperature is 43 to 45 degrees F. The frost-free season is 90 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Anglen, Cedonia, Hartill, and Lakesol soils and the competing Hodgson soil. Anglen soils have a mantle of volcanic ash 7 to 14 inches thick. Cedonia soils lack an argillic horizon, are fine-silty and mesic. Hartill soils are 20 to 40 inches to bedrock. Lakesol soils have a mollic epipedon 7 to 12 inches thick and are coarse-silty and lack an argillic horizon.
DRAINAGE AND PERMEABILITY: Moderately well drained; moderately slow permeability; very slow to medium runoff.
USE AND VEGETATION: Used for hay and pasture, building sites, timber production, livestock grazing, and wildlife habitat. Native plant association is Douglas- fir/mallow ninebark, with an overstory of Douglas-fir, western larch, and ponderosa pine, and an understory of mallow ninebark, creambush oceanspray, common snowberry, pachystima, pinegrass, sweetscented bedstraw, and sidebells pyrola.
DISTRIBUTION AND EXTENT: Northeastern Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Colville Indian Reservation; Ferry County, Washington, 1987.
REMARKS: Diagnostic horizons and features recognized in this soil are an ochric epipedon from the mineral surface to 6 inches with an estimated organic carbon content of 1 to 2 percent, and an argillic horizon from 12 to 44 inches with tongues of albic material in the part from 10 to 16 inches. The description reflects a change in classification from fine, mixed, frigid Vitrandic Palexeralfs to fine, isotic, frigid Vitrandic Palexeralfs.