LOCATION POWEEN WAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Cumulic Haploxerolls
TYPICAL PEDON: Poween loam - on a 4 percent slope at 2,560 feet elevation, under native range vegetation. (Colors are for dry soil unless otherwise stated)
A1--0 to 12 inches; very dark gray (10YR 3/1) loam, black (10YR 2/1) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and nonplastic; many very fine and fine roots; 5 percent pebbles; moderately alkaline (pH 8.0); gradual wavy boundary. (5 to 21 inches thick)
A2--12 to 30 inches; dark grayish brown (10YR 4/2) sandy loam, very dark gray (10YR 3/1) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and nonplastic; many very fine and fine roots; 10 percent pebbles; violently effervescent; strongly alkaline (pH 8.8); clear wavy boundary. (7 to 20 inches thick)
AC--30 to 44 inches; grayish brown (10YR 5/2) sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and nonplastic; common fine roots; 10 percent pebbles; violently effervescent; strongly alkaline (pH 8.8); clear wavy boundary. (5 to 18 inches thick)
C--44 to 60 inches; light brownish gray (10YR 6/2) loam, dark grayish brown (10YR 4/2) moist; massive; soft, very friable, slightly sticky and nonplastic; few fine roots; 10 percent pebbles; violently effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Colville Indian Reservation; Okanogan County, Washington; about 6 miles southeast of the town of Nespelem; 1,800 feet south, 600 feet east of the northwest corner of sec. 12, T. 30 N., R. 31 E., W.M.
RANGE IN CHARACTERISTICS: The mean annual soil temperature at a depth of 20 inches is 49 to 51 degrees F. These soils are usually moist but are dry between depths of 8 and 24 inches for 75 to 90 consecutive days following the summer solstice. The mollic epipedon is 20 to 50 inches thick. The particle-size control section averages 5 to 18 percent clay and is 0 to 15 percent rock fragments. Reaction is moderately alkaline or strongly alkaline throughout.
The A horizon has value of 3 through 5 dry, 2 or 3 moist, and chroma of 1 through 3 dry or moist. It is loam, fine sandy loam, or sandy loam in the lower part and is 0 to 10 percent pebbles.
The AC horizon has value of 5 or 6 dry, 3 or 4 moist, and chroma of 2 or 3 dry or moist. It is sandy loam, silt loam or loam and is 0 to 10 percent pebbles.
The C horizon has hue of 10YR or 2.5Y, value of 6 or 7 dry, 4 ore 5 moist, and chroma of 1 through 3 dry or moist. It is loam, silt loam, or fine sandy loam and may have thin lenses of sandy loam or loamy fine sand. Some pedons have few fine strong brown mottles below a depth of 40 inches. Pebble content ranges from 0 to 15 percent.
COMPETING SERIES: These are the Coxlake, Deerspring, Endersby, Evans, Flofeather, Leavenworth, Lapwai, Narcisse, Okanogan, Patit Creek, Pleasant View, Plinco, Porter, Redola, Threecreeks, and Tombeall series. Coxlake soils have mottles in the control section and are neutral throughout. Deerspring and Endersby soils are dry for more than 90 consecutive days horizon. Evans soils are slightly acid in the particle-size control section. Flofeather soils are somewhat excessively drained and are noncalcareous throughout. Leavenworth soils are non-calcareous in the particle-size control section are are neutral to slightly alkaline throughout. Lapwai soils have 2Bk horizons. Narcisse soils are slightly acid or neutral and are dry in the moisture control section for 60 to 80 consecutive days. Okanogan soils are noncalcareous in the upper 44 inches and are dry for 90 to 105 consecutive days. Patit Creek soils have an extremely gravelly 2C horizon at a depth of 20 to 40 inches and are dry for 60 to 75 consecutive days. Pleasant View soils are gravelly in the particle-size control section and have a zone of carbonate accumulation that has a calcium carbonate equivalent of 12 to 25 percent. Plinco and Porter soils are noncalcareous throughout. Redola soils are calcareous throughout. Threecreeks and Tombeall soils have 2C horizons and are noncalcareous throughout.
GEOGRAPHIC SETTING: Poween soils are on stream terraces and alluvial fans with slopes of 0 to 5 percent. These soils formed in calcareous alluvium of mixed mineralogy. Elevations range from 1,600 to 2,600 feet. The climate is characterized by warm, dry summers and cool, moist winters. The average annual precipitation is 12 to 15 inches. The mean January temperature is about 25 degrees F, the mean July temperature is about 71 degrees F, and the mean annual air temperature is about 48 degrees F. The frost-free season is 110 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bossburg, Emdent, Haley and Nespelem soils. Bossburg soils are very poorly drained and have a histic epipedon. Emdent soils are ashy and sodic. Haley soils are well drained and coarse-loamy over sandy or sandy-skeletal. Nespelem soils are well drained and coarse-silty.
DRAINAGE AND PERMEABILITY: Moderately well drained; very slow runoff; moderate permeability.
USE AND VEGETATION: Principal uses are livestock grazing, hay and pasture, watershed, and wildlife habitat. The native vegetation is basin wildrye, inland saltgrass, Dutch rush, and common yarrow.
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; Okanogan County, Washington, 1987.
REMARKS: Diagnostic horizons and features recognized in this soil are a mollic epipedon from the surface to 44 inches, and an irregular decrease in organic carbon with depth (inferred from the stratified nature of the parent material).