LOCATION KOSETH WAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Vitrandic Haploxerepts
TYPICAL PEDON: Koseth ashy loam, forested. (Colors are for dry soil unless otherwise stated.)
Oi&Oe--0 to 0.5 inch; partially decomposed organic litter, composed of needles, leaves, twigs, bark and cones; abrupt smooth boundary. (1/2 to 3 inches thick)
A--0.5 to 3 inches; grayish brown (10YR 5/2) ashy loam, very dark grayish brown (10YR 3/2) moist; weak medium and coarse granular structure; soft, friable, slightly sticky and slightly plastic; many fine, few medium and coarse roots; many fine pores; 10 percent rounded pebbles; neutral (pH 7.2); clear wavy boundary. (3 to 5 inches thick)
Bw--3 to 8 inches; pale brown (10YR 6/3) gravelly ashy loam, brown (10YR 4/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine, few medium and coarse roots; many fine pores; 15 percent rounded pebbles; slightly alkaline (pH 7.4); clear wavy boundary. (5 to 8 inches thick)
BC--8 to 16 inches; pale brown (10YR 6/3) gravelly loam, brown (10YR 4/3) moist; weak medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine, few medium and coarse roots; many fine pores; 20 percent rounded pebbles; strongly effervescent; slightly alkaline (pH 7.8); clear wavy boundary. (6 to 10 inches thick)
C1--16 to 31 inches; pale yellow (5Y 7/3) gravelly loam, olive (5Y 4/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few roots; common fine, few medium and coarse roots; common fine pores; 25 percent rounded pebbles; violently effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (16 to 20 inches thick)
C2--31 to 44 inches; pale yellow (2.5Y 7/4) gravelly loam, light olive brown (2.5Y 5/4) moist; massive; hard, friable, slightly sticky and slightly plastic; few roots; few fine pores; 30 percent rounded pebbles; violently effervescent; moderately alkaline (pH 8.2). (14 to 20 inches thick)
C3--44 to 60 inches; pale yellow (2.5Y 7/4) very gravelly loam, light olive brown (2.5Y 5/4) moist; massive; hard, friable, slightly sticky and slightly plastic; few pores; 40 percent rounded pebbles; violently effervescent; moderately alkaline (pH 8.2). (14 to 20 inches thick)
TYPE LOCATION: Stevens County, Washington; 2,400 feet north, 50 feet west of SE corner sec. 20, T.36N., R.40E., M.W. 33T-161.
RANGE IN CHARACTERISTICS: The soil is usually moist in all horizons during part of the year but is dry in all parts between depths of 8 to 24 inches for 60 to 80 consecutive days during summer and autumn. The mean annual soil temperature at a depth of 20 inches ranges from 48 to 50 degrees F. The particle-size control section has 15 to 35 percent rounded pebbles and cobbles. The soil is neutral to moderately alkaline.
The A horizon has chroma of 2 or 3. It has fine, medium or coarse granular, or very fine and fine subangular blocky structure. Gravel ranges from 5 to 10 percent. This horizon is neutral or slightly alkaline.
The Bw horizon has value of 6 or 7 dry and 4 or 5 moist. It has fine to coarse subangular blocky structure. Gravel ranges from 15 to 25 percent. This horizon is neutral or slightly alkaline.
The BC horizon has value of 6 or 7 dry and 4 or 5 moist. It has fine to coarse subangular blocky structure. Gravel ranges from 15 to 30 percent.
The C horizon has hue of 2.5Y or 5Y, value of 6 or 7 dry, 4 or 5 moist and chroma of 3 or 4. Gravel ranges from 15 to 30 percent in the upper part and from 35 to 50 percent in the lower part.
COMPETING SERIES: These are the Barron, Bestrom, cassolary, Clayton, Frailey, Green Bluff, Koerling, Lierling, Scala, Siskiyou and Stoner series. Barron, cassolary, Clayton, Frailey, Green Bluff, Scala, Siskiyou and Stoner soils are not calcareous. Bestrom soils are 20 to 24 inches deep to basalt. Koerling soils have calcareous lake sediments and have a lithologic discontinuity at a depth of 24 to 40 inches.
GEOGRAPHIC SETTING: Koseth soils are on glaciated uplands, glaciated hillsides and mountain slopes at elevations of 1,600 to 4,000 feet. Slopes are usually undulating, rolling, or convex and range from 15 to 65 percent. Aspect is mostly southerly. These soils formed in till from limestone and fine and medium textured calcareous shaly rock with a component of volcanic ash and loess in the upper horizons. Koseth soils are in a continental climate having but dry summers and cool moist winters. The average annual temperature is 46 to 48 degrees F. The average annual precipitation ranges from 15 to 30 inches; and the frost-free season is 90 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aits, Belzar, Donavan, Maki, Molcal, Stevens and Watts soils. Aits, Donavan and Stevens soils are not calcareous in the upper part of the control section. Aits, Belzar and Waits soils are frigid. Belzar and Maki soils are 20 to 40 inches deep. Molcal and Stevens soils have a mollic epipedon.
DRAINAGE AND PERMEABILITY: Well drained; slow to very rapid runoff; moderate permeability.
USE AND VEGETATION: Cropland, woodland and grazable woodland. Native overstory vegetation is usually ponderosa pine, Douglas-fir and western larch. Understory and ground vegetation is ninebark, snowberry wild rose, Oregon grape, yarrow, mullin, strawberry and pinegrass.
DISTRIBUTION AND EXTENT: Upland areas in Stevens County, Washington including those adjacent to the Mill Creek drainage system northeast of Colville. Koseth soils are inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Stevens County, Washington, 1978.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
ochric epipedon from the mineral surface to 3 inches; (A horizon)
cambic horizon from 3 to 16 inches, (Bw and BC horizons)
The upper 8 inches of the mineral soil is assumed to have a sum of the product of [1/2 Fe(ox) + Al(ox)] time 60 plus the volcanic glass of more than 30.