LOCATION KOEPKE WAEstablished Series
TAXONOMIC CLASS: Ashy over loamy, glassy over isotic, frigid Humic Vitrixerands
TYPICAL PEDON: Koepke ashy loam, grassland. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 1 inch; slightly decomposed needles, twigs and grass; abrupt smooth boundary.
A1--1 to 10 inches; very dark gray (10YR 3/1) ashy loam, black (10YR 2/1) moist; weak very fine granular structure; soft, very friable, nonsticky and nonplastic; common roots; common fine pores; 10 percent gravel; neutral (pH 6.6); diffuse wavy boundary. (5 to 9 inches thick)
A2--10 to 19 inches; very dark gray (10YR 3/1) ashy loam, black (10YR 2/1) moist; massive; soft, very friable, nonsticky and nonplastic; common roots; common fine pores; 2 percent gravel; neutral (pH 6.8); abrupt wavy boundary. (5 to 13 inches thick)
A3--19 to 29 inches; very dark gray (10YR 3/1) ashy sandy loam, black (10YR 2/1) moist; massive; soft, very friable, nonsticky and nonplastic; common roots; common fine pores; neutral (pH 6.8); clear irregular boundary. (2 to 10 inches thick)
2A4--29 to 35 inches; dark grayish brown (10YR 4/2) gravelly sandy loam, very dark brown (10YR 2/2) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common roots; common fine pores; 20 percent gravel; neutral (pH 6.9); clear wavy boundary. (0 to 10 inches thick)
2Bw--35 to 42 inches; pale brown (10YR 6/3) gravelly sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few roots; few fine pores; 30 percent gravel; neutral (pH 6.9); abrupt wavy boundary. (6 to 20 inches thick)
2Cd1--42 to 50 inches; light brownish gray (10YR 6/2) gravelly sandy loam, dark grayish brown (10YR 4/2) moist; massive; hard, friable, nonsticky and nonplastic; few roots; few fine pores; 30 percent gravel; neutral (pH 6.9); abrupt wavy boundary. (8 to 13 inches thick)
2Cd2--50 to 60 inches; light gray (2.5Y 7/2) very gravelly sandy loam, grayish brown (2.5Y 5/2) moist; massive; hard, friable, slightly sticky and nonplastic; 40 percent gravel; strongly effervescent; strongly alkaline (pH 8.5).
TYPE LOCATION: Ferry County, Washington; 500 feet south on Catherine Creek Road from fence crossing and 40 feet south of road in the SE1/4 SE1/4 sec. 2, T.40N., R.32E.
RANGE IN CHARACTERISTICS:
Soil moisture: usually moist but are dry in all parts for 60 to 75 consecutive days following the summer solstice; xeric soil moisture regime
Soil temperature: mean annual soil temperature is 43 to 47 degrees F.
Rock fragments: 0 to 20 percent in the upper part and 15 to 35 percent in the lower part of the particle-size control section
Depth to secondary carbonates: 40 to more than 60 inches
Depth to densic material: 40 to 60 inches
Thickness of the ash mantle (andic soil properties): 14 to 30 inches
Andic soil properties: has an estimated moist bulk density of 0.65 to 0.85 g/cc, volcanic glass content of 30 to 60 percent, acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of 1.0 to 2.0 percent, and 15-bar water retention of 5 to 12 percent for air dried sample
Mollic epipedon: 20 to 40 inches thick
A horizon
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 1 to 3, dry or moist
Texture: ashy loam, ashy silt loam or ashy sandy loam and can be gravelly
Gravel: 0 to 20 percent
Reaction: slightly acid or neutral
Organic carbon content: 5 to 8 percent
2A horizon.
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 1 to 3, dry or moist
Texture: gravelly sandy loam or gravelly loam
Gravel: 15 to 35 percent gravel
Reaction: slightly acid or neutral
2Bw or 2C horizon
Hue: 10YR or 2.5Y
Value: 5 or 6 dry, 3 to5 moist
Chroma: 2 to 4, dry or moist
Texture: gravelly sandy loam, gravelly loam, cobbly loam, or cobbly sandy loam
Gravel: 15 to 35 percent
Cobbles: 0 to 10 percent
2Cd horizon
Hue:10YR or 2.5Y
Value: 5 to 7 dry, 3 or 4 moist
Chroma: 2 or 3, dry or moist
Texture: gravelly sandy loam, gravelly loam, very gravelly sandy loam, very gravelly loam, very cobbly loam, or very cobbly sandy loam
Reaction: neutral to strongly alkaline.
Gravel: 15 to 40 percent
Cobbles: 0 to 25 percent
Can be calcareous in some pedons
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Koepke soils are on footslopes and backslopes of glaciated hills and mountains. Slope ranges from 0 to 45 percent. These soils formed in volcanic ash over glacial till. Elevations are 1,900 to 4,800 feet. The climate is characterized by warm, dry summers and cool, moist winters. The mean annual precipitation is 14 to 24 inches. The mean January temperature is about 23 degrees F, the mean July temperature is about 64 degrees F, and the mean annual air temperature is 42 to 43 degrees F. The frost-free season is 90 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hunters, Louploup, Mires, Molson, Nevine, Republic, and Scoap soils. Hunters soils are fine-silty, have a mesic temperature regime, and are on terraces. Louploup soils do not have a mollic epipedon and are on till plains and mountains. Mires soils are ashy over sandy or sandy-skeletal and are on terraces. Nevine soils do not have a mollic epipedon, are ashy over loamy-skeletal and are on moraines, foothills and mountains. Republic soils have a mollic epipedon less than 20 inches thick and are on alluvial fans and terraces. Scoap soils are loamy-skeletal and are on uplands and mountainsides.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate over slow permeability.
USE AND VEGETATION: Used mainly for timber production, livestock grazing, dryland cropland, hay and pasture, and wildlife habitat. Native vegetation is Douglas-fir, ponderosa pine and scattered western larch. Understory species include common snowberry, Saskatoon serviceberry, rose, pinegrass, blue wildrye, silky lupine, spreading sweetroot, and gland cinquefoil.
DISTRIBUTION AND EXTENT: North central Washington. MLRA 43A. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Ferry County (Ferry County Area), Washington, 1971.
REMARKS: Diagnostic horizons and features recognized in this soil are:
Mollic epipedon from 1 to 35 inches (A1, A2, A3 and 2A4 horizons)
Cambic horizon from 35 to 42 inches (2Bw horizon)
Densic contact at 42 inches (Cd horizon)
Andic soil properties from 1 to 29 inches (A1, A2 and A3 horizons)
The series was originally classified as ashy over loamy, mixed, frigid Mollic Vitrandepts
ADDITIONAL DATA: Partial laboratory data are available on this series, NSSL Numbers 64400-405 and 64406-411