LOCATION SAPKIN WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Ultic Argixerolls
TYPICAL PEDON: Sapkin very stony loam - rangeland. (Colors are for dry soil unless otherwise stated. All textures are apparent field textures).
A1--0 to 5 inches; brown (10YR 5/3) very stony loam, very dark grayish brown (10YR 3/2) moist; weak very fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and very fine roots; many very fine irregular pores; 15 percent gravel, 30 percent cobbles and 10 percent stones; slightly acid (pH 6.4); clear smooth boundary.
A2--5 to 16 inches; brown (10YR 5/3) very cobbly loam, dark brown (10YR 3/3) moist; weak very fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and very fine roots; many very fine irregular pores; 15 percent gravel, 35 percent cobbles and 5 percent stones; slightly acid (pH 6.4); gradual smooth boundary. (Combined thickness of the A horizon is 7 to 18 inches)
AB--16 to 25 inches; brown (10YR 5/3) very cobbly loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure and weak fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and very fine roots; common very fine tubular pores; 15 percent gravel, 35 percent cobbles and 5 percent stones; neutral (pH 6.6); gradual smooth boundary. (0 to 12 inches thick)
Bt--25 to 36 inches; yellowish brown (10YR 5/4) very cobbly heavy loam, dark yellowish brown (10YR 3/4) moist; weak coarse subangular blocky structure; slightly hard, firm, slightly sticky and moderately plastic; common fine and very fine roots; common very fine tubular pores; few distinct clay films in pores; 15 percent gravel, 35 percent cobbles and 5 percent stones; slightly acid (pH 6.4); abrupt irregular boundary. (4 to 12 inches thick)
R--36 inches; fractured basalt.
TYPE LOCATION: Kittitas County, Washington; about 23 miles northeast of Ellensburg; 2,700 feet east and 100 feet south of the northwest corner section 32, T. 20 N., R. 21 E.; USGS Stray Gulch, Washington topographic quadrangle; latitude 47 degrees, 11 minutes, 23 seconds N. and Longitude 120 degrees, 13 minutes, 42 seconds W. (NAD 27).
RANGE IN CHARACTERISTICS: Average annual soil temperature ranges from 44 to 47 degrees F. The soil is dry in all parts between depths of 4 to 12 inches for 75 to 90 consecutive days after the summer solstice. Depth to a lithic contact ranges from 20 to 40 inches. The mollic epipedon is 10 to 19 inches thick. Base saturation is 50 to 75 percent. The particle-size control section is 40 to 80 percent rock fragments by volume and 18 to 30 percent clay by weight. Soil reaction is slightly acid or neutral.
The A horizon has hue of 5YR to 10YR, value of 2 or 3 moist, 3 to 5 dry and chroma of 2 or 3 moist and dry. Texture of the A2 horizon, when present, is cobbly loam or very cobbly loam.
The AB horizon has colors intermediate to the A and Bt horizon. Texture is cobbly loam or very cobbly loam. The AB horizon is absent in some pedons.
The Bt horizon has hue of 5YR to 10YR, value of 4 or 5 dry, 3 or 4 moist and chroma of 3 to 6 moist and dry. It has 40 to 80 percent rock fragments, mainly basalt and 0 to 30 percent parafragments. Texture is very cobbly or extremely cobbly and is loam or clay loam.
COMPETING SERIES: These are the
Apmat,
Brassey,
Durst,
Fergie,
Fraval,
Henhoit,
Little Wood,
Morningstar,
Mulshoe and
Sattley series.
Apmat soils greater than 60 inches to bedrock
Brassey soils greater than 60 inches to bedrock; dry for 60 to 75 consecutive days following the summer solstice
Durst soils 20 to 32 inches to a lithic contact (quartzite); pscs dominated by rock fragments of quartzite origin; MAST is 40 to 43 degrees F.
Fergie soils 40 to 60 inches to a lithic contact (basalt); dry 90 to 120 consecutive days following the summer solstice
Fraval soils 20 to 40 inches to a paralithic contact (tuff)
Henhoit soils greater than 60 inches to bedrock; pscs dominated with 35 to 75 percent rounded quartzite and sandstone rock fragments
Little Wood soils greater than 60 inches to bedrock; 21 to 34 inches to sandy-skeletal C horizon
Morningstar soils 40 to greater than 60 inches to bedrock
Mulshoe soils dry for 90 to 110 consecutive days following the summer solstice
Sattley soils 40 to 60 inches to a lithic contact (andesitic conglomerate or tuff breccia); dry greater than 90 consecutive days following the summer solstice
GEOGRAPHIC SETTING: Sapkin soils are on mountain side slopes and ridgetops. Slopes are 0 to 75 percent. These soils formed in residuum and colluvium derived from Yakima basalt mixed with small amounts of loess and volcanic ash. Elevation is 2,400 to 5,600 feet. These soils are in a climate with warm, dry summers and cool, moist winters. The average annual precipitation is 18 to 35 inches. The average January temperature is about 24 degrees F., and the average July temperature is about 67 degrees F. The average annual temperature is 42 to 46 degrees F. The growing season at 28 degrees F. is 145 days to 170 days, and the frost-free season at 32 degrees F. is 70 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Anatone, Bocker, Jumpe, Loneridge and Sutkin soils on mountain side slopes. Anatone and Bocker soils are shallow to basalt. Jumpe soils have an ochric epipedon and are deep. Loneridge soils are deep, lack a mollic epipedon and are clayey-skeletal. Sutkin soils are deep and lack an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderate permeability.
USE AND VEGETATION: These soils are used for livestock grazing, recreation, wildlife habitat and watershed. Vegetation is bluebunch wheatgrass, Junegrass and bitterbrush.
DISTRIBUTION AND EXTENT: South central, Washington. The series is moderately extensive.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Yakima County, Washington, 1979.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from 0 to 16 inches
Argillic horizon - the zone from 25 to 36 inches
Lithic contact - the zone beginning at 36 inches
Particle-size control section -the zone from 25 to 36 inches (the Bt horizon).