LOCATION SWIPKIN WAEstablished Series
TAXONOMIC CLASS: Coarse-silty, isotic, mesic Vitrandic Haploxerolls
TYPICAL PEDON: Swipkin ashy silt loam - on a 3 percent northwest-facing slope at 2,630 feet elevation, under a ponderosa pine canopy. (Colors are for dry soil unless otherwise noted. All textures are apparent field textures.)
A1--0 to 7 inches; dark grayish brown (10YR 4/2) ashy silt loam, very dark brown (10YR 2/2) moist; weak very fine subangular blocky structure, soft, very friable, slightly sticky, slightly plastic; common very fine and fine roots; neutral (pH 6.8); clear smooth boundary.
A2--7 to 16 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky, slightly plastic; common very fine and fine, few medium roots; neutral (pH 6.8); gradual smooth boundary (Combined thickness of the A horizon is 7 to 17 inches).
Bw--16 to 21 inches; light yellowish brown (10YR 6/4) silt loam, dark yellowish brown (10YR 3/4) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine and fine roots; 1 percent pebbles; neutral (pH 6.6); clear smooth boundry (5 to 20 inches thick)
C1--21 to 44 inches; light brownish gray (2.5Y 6/2) silt loam, dark grayish brown (2.5Y 4/2) moist; massive; hard, friable, slightly sticky, slightly plastic; few very fine roots; 2 percent pebbles; neutral (pH 6.8); gradual smooth boundary. (5 to 24 inches thick)
C2--44 to 60 inches; light brownish gray (2.5Y 6/2) silt loam, dark grayish brown (2.5Y 4/2) moist; massive (varved); hard, friable, slightly sticky, slightly plastic; few very fine roots between varve planes, 2 percent pebbles, slightly alkaline (pH 7.6).
TYPE LOCATION: Colville Indian Reservation; Okanogan County, Washington; about 1 1/2 miles west of the town of Disautel; 1,800 feet east, 850 feet north of the southwest corner of sec. 14, T. 33 N., R. 28 E., W.M.
RANGE IN CHARACTERISTICS: The mean annual soil temperature at a depth of 20 inches ranges from 47 to 49 degrees F. These soils are usually moist but are dry between depths of 4 and 12 inches for 75 to 90 consecutive days following the summer solstice. The mollic epipedon is 7 to 17 inches thick. 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 particle-size control section is 10 to 18 percent clay, and less than 15 percent material coarser than very fine sand, including 0 to 5 percent pebbles. Base saturation (by sum of cations) is assumed to be less than 75 percent in some or all parts of the upper 30 inches.
The A horizon has value of 4 or 5 dry, 2 or 3 moist, and chroma of 3 or 4 dry or moist. Reaction is slightly acid or neutral.
The Bw horizon has hue of 10YR or 2.5Y, value of 5 or 6 dry, 3 or 4 moist, and chroma of 3 or 4 dry or moist. When moist value is 3, moist chroma is 4. It is silt loam or very fine sandy loam and is 0 to 5 percent pebbles.
The C horizon has hue of 10YR or 2.5Y, value of 6 through 8 dry, 4 through 6 moist, and chroma of 2 through 4 dry or moist. It is silt loam or very fine sandy loam and is 0 to 10 percent pebbles. Reaction is neutral or slightly alkaline above a depth of 44 inches, and neutral to moderately alkaline below this depth. Some pedons are calcareous and contain secondary carbonates below a depth of 44 inches.
COMPETING SERIES: This is the Inchelium series. Inchelium soils have a mollic epipedon 20 to 42 inches thick.
GEOGRAPHIC SETTING: Swipkin soils are on lake plains, terraces, and terrace escarpments. These soils formed in glacial lake sediments with a component of loess and volcanic ash in the upper part. Slopes are 0 to 25 percent. Elevations range from 1,450 to 2,800 feet. The climate is characterized by warm, dry summers and cool, moist winters. The average annual precipitation is 15 to 18 inches. The mean January temperatures is about 24 degrees F, the mean July temperature is about 67 degrees F, and the mean annual air temperature is about 46 degrees F. The frost-free season is 100 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bernhill, Bisbee, Cedonia, Donavan, Hudnut, and Omak series. Bernhill soils are fine-loamy and have an ochric epipedon. Bisbee soils are sandy throughout the profile. Cedonia soils are fine-silty and have an ochric epipedon. Donavan and Hudnut soils are coarse-loamy. Omak soils are fine and have a duripan at a depth of 20 to 40 inches.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderately slow permeability.
USE AND VEGETATION: Timber production, livestock grazing, and hay pasture are the principal uses. These soils hae potential for both irrigated and nonirrigated cultivated crops on gentler slopes. Native vegetation is mainly ponderosa pine with scattered Douglas-fir. Understory species include common snowberry, Saskatoon serviceberry, white spiraea, rose, pinegrass, blue wildrye, silky lupine, gland cinquefoil, and Virginia strawberry.
DISTRIBUTION AND EXTENT: Northcentral 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 area a mollic epipedon from the surface to 16 inches, a cambic horizon from 16 to 21 inches, and a coarse-silty 10- to 40-inch particle-size control section. The description reflects a change in classification from coarse-silty, mixed, mesic Vitrandic Haploxerolls to coarse-silty, isotic, mesic Vitrandic Haploxerolls.