LOCATION SHUSHUSKIN WATentative Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Vitrandic Argixerolls
TYPICAL PEDON: Shushuskin loam- dryland cropland on a 10 percent east-facing slope at an elevation of 2,240 feet. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 4 inches; dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; weak fine and medium granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine roots; common very fine irregular and few very fine tubular pores; slightly acid (pH 6.2); abrupt smooth boundary. (4 to 6 inches thick)
A--4 to 8 inches; dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; moderate medium and coarse platy structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; common very fine irregular and few very fine tubular pores; slightly acid (pH 6.2); abrupt smooth boundary. (3 to 5 inches thick)
AB--8 to 13 inches; brown (10YR 4/3) loam, very dark grayish brown (10YR 3/2) moist; moderate medium prismatic structure parting to moderate fine and medium subanular blocky ; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; common very fine irregular and tubular pores; 10 percent very coarse cylindrical cicada cast; neutral (pH 6.8); abrupt wavy boundary. (3 to 7 inches thick)
2Bt1--13 to 19 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; moderate medium prismatic structure parting to moderate fine and medium subangular blocky; hard, firm, slightly sticky and slightly plastic; common very fine roots; common very fine tubular pores; common distinct pressure faces on peds and few faint clay bridging in pores; 15 percent very coarse cylindrical cicada cast; 5 percent pebbles; neutral (pH 6.8); clear wavy boundary.
2Bt2--19 to 23 inches; brown (10YR 5/3) clay loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure parting to moderate fine subangular blocky; very hard, firm, moderately sticky and moderately plastic; common very fine roots; common very fine tubular pores; many distinct pressure faces on peds, few distinct brown (10YR 4/3) pressure faces on vertical faces of peds, and common distinct brown (10YR 4/3) clay films and clay bridging pores; 15 percent very coarse cylindrical cicada cast; 5 percent pebbles; neutral (pH 7.0); clear wavy boundary. (Combined Bt horizon is 7 to 18 inches thick)
3Btb--23 to 32 inches; yellowish brown (10YR 5/4) very gravelly clay loam, dark yellowish brown (10YR 3/4) moist; moderate medium subangular blocky structure parting to fine subangular blocky; very hard, firm, moderately sticky and moderately plastic; few very fine roots; common very fine tubular pores; many distinct pressure faces on peds, few distinct dark brown (7.5YR 3/4) clay films on faces of peds, and many distinct dark brown (7.5YR 3/4) clay films and clay bridging in pores; 30 percent pebbles and 15 percent cobbles; neutral (pH 7.0); abrupt irregular boundary. (3 to 10 inches thick)
4R--32 inches; fractured basalt.
TYPE LOCATION: Kittitas County, Washington; about 5.5 miles south of Thorp, WA., about 400 feet west and 1,500 feet north of the southeast corner of section 3, T. 17 N., R. 17 E.; USGS Manastash Creek, Wash. topographic quadrangle; Latitude 46 degrees, 59 minutes, 22 seconds N. and Longitude 120 degrees, 40 minutes, 14 seconds W.
RANGE OF CHARACTERISTICS: The mean annual soil temperature at a depth of 20 inches is 47 to 52 degrees F. These soils are usually moist but are dry in the moisture control section for 75 to 90 consecutive days following the summer solstice. Thickness of the mollic epipedon is 20 to 35 inches and includes the upper part of the argillic horizon. The upper 10 to 18 inches has an estimated bulk density of 1.10 to 1.30 g/cc, volcanic glass 7 to 25 percent, acid oxalate extractable aluminum plus one-half of the acid oxalate extractable iron of 0.4 to 0.7 percent, and the 15-bar water retention of 5 to 10 percent for air dried samples. The particle-size control section has 27 to 35 percent clay and more than 15 percent fine sand or coarser. It has 5 to 15 percent rock fragments by volume. Organic matter is estimated to range from 3 to 5 percent in the Ap and A horizons. Solum thickness and depth to lithic contact with basalt is 20 to 40 inches.
The Ap horizon has value of 3 or 4 dry and chroma of 1 or 2 dry or moist. It is slightly acid or neutral.
The A horizon has value of 3 or 4 dry and chroma of 1 or 2 dry or moist. It is loam or silt loam. It is slightly acid or neutral.
The AB horizon has value of 3 or 4 dry, and 2 or 3 moist, and chroma of 2 or 3 dry or moist. It is slightly acid or neutral. It is silt loam or loam.
The 2Bt horizons have value of 4 or 5 dry, and 2 or 3 moist, and chroma of 2 or 3 dry or moist. The 2Bt1 horizon is silt loam, loam, or clay loam. The 2Bt2 horizon is clay loam or silty clay loam.
The 3Btb horizon has value of 4 or 5 dry and chroma or 3 or 4 dry or moist. It is very gravelly clay loam, clay loam or gravelly clay loam.
COMPETING SERIES: These are the Georgecreek, Glenrose, Morical, Mozen(T), Pachneum(T), Ralock, Rollinger, Teewee(T), Tolius, Umperon, Volinger(T) and Wockum series. Georgecreek soils are 40 to 60 inches to a paralithic contact and have mollic epipedon 8 to 16 inches thick. Glenrose soils have mollic less than 20 inches thick and average less than 25 percent clay in the fine earth fraction. Morical soils are 20 to 40 inches to paralithic contact and have a mollic epipedon less than 20 inches thick. Pachneum and Umperon soils are greater than 60 inches to a lithic contact. Mozen soils have secondary carbonates at a depth of 23 to 37 inches and are dry for 90 to 100 consecutive days. Ralock and Rollinger soils are greater than 60 inches to lithic contact and are dry for 100 to 120 consecutive days. Teewee soils are 40 to 60 inches to a paralithic contact and have a mollic epipedon less than 20 inches thick. Tolius and Wockum soils are very deep to bedrock.
GEOGRAPHIC SETTING: Shushuskin soils are on hillslopes, dissected plateaus and piedmont slopes and have slopes of 3 to 30 percent. These soils formed in loess mixed with volcanic ash in the surface, slope alluvium and some residuum from basalt. Elevation is 2,000 to 3,600 feet. These soils are in a semiarid climate with warm dry summers and cool moist winters. Average annual precipitation is 15 to 18 inches. Average January temperature is about 25 degrees F. and average July temperature is about 69 degrees F. Average annual temperature is 46 to 49 degrees F. The frost-free season is 110 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Pachneum soils and the Laufer, McDaniel, Nint and Shinn soils. Pachneum soils are on hillslopes, footslopes, dissected plateaus and piedmont slopes. Laufer soils are on canyon walls and have lithic contact at a depth of 10 to 20 inches. McDaniel and Nint soils are on canyon walls and hillsopes, and have more than 35 percent rock fragments in the particle-size control section. Shinn soils are on broad ridges and have lithic contact at a depth of 4 to 10 inches.
DRAINAGE AND PERMEABILITY: Well drained, slow to medium runoff; moderately slow permeability.
USE AND VEGETATION: Used for dryland cropland, livestock grazing and wildlife habitat. Native vegetation is bluebunch wheatgrass, Idaho fescue, Sandberg bluegrass and Wyoming sagebrush.
DISTRIBUTION AND EXTENT: Kittitas County, Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Kittitas County, Washington, l990. The name is derived from Shushuskin Canyon.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon (pachic) - 0 to 23 inches (Ap, AB, 2Bt1, and 2Bt2 horizons)
Argillic horizon -13 to 32 inches (2Bt1, 2Bt2, and 2Btb horizons)
PSCS - the zone from 13 to 32 inches (the 2Bt1, 2Bt2, and 3Btb horizon)
Vitrandic feature - 0 to 13 inches (Ap, A, and AB horizons)
This draft reflects a change in classification from mixed, mesic Pachic Argixerolls to mixed, superactive, mesic Vitrandic Argixerolls.