LOCATION SPLITTOP IDEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, frigid Xeric Haplocalcids
TYPICAL PEDON: Splittop loam on a 2 percent slope at an elevation of 5,150 feet in rangeland. When described on July 17, 1979, the profile was dry throughout. (Colors are for dry soil unless otherwise noted)
A--0 to 3 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist, weak coarse platy structure; soft, very friable, nonsticky and nonplastic; many very fine roots; few very fine irregular pores about 5 percent cobbles; slightly alkaline (pH 7.4); abrupt smooth boundary. (1 to 6 inches thick)
Bw1--3 to 10 inches; pale brown (10YR 6/3) loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; soft, friable, slightly sticky and nonplastic; common very fine roots; common very fine and fine tubular pores; slightly alkaline (pH 7.8); gradual smooth boundary. (0 to 14 inches thick)
Bw2--10 to 15 inches; pale brown (10YR 6/3) loam, brown (10YR 5/3) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine and fine tubular pores; slightly alkaline (pH 7.6); abrupt smooth boundary. (0 to 5 inches thick)
Bk1--15 to 26 inches; very pale brown (10YR 8/3) silt loam; very pale brown (10YR 7/3) moist; massive; hard, firm, slightly sticky and slightly plastic; few very fine and fine roots; common fine tubular pores; strongly effervescent (20 percent calcium carbonate equivalent); moderately alkaline (pH 8.4); abrupt wavy boundary.
2Bk2--26 to 32 inches; very pale brown (10YR 7/3) very cobbly loam, pale brown (10YR 6/3) moist; massive; slightly hard, firm, slightly sticky and slightly plastic; few very fine roots; few very fine tubular pores; strongly effervescent (20 percent calcium carbonate); about 50 percent cobbles; moderately alkaline (pH 8.4), abrupt wavy boundary. (Combined thickness of the Bk horizon is 6 to 20 inches)
2R--32 inches; basalt
TYPE LOCATION: Blaine County; 2,000 feet north and 1,000 feet east of the southwest corner of sec. 2, T. 3 S., R. 29 E. Latitude 43 degrees, 11 minutes, and 01 seconds north; Longitude 113 degrees, 02 minutes, and 29 seconds west.
RANGE IN CHARACTERISTICS:
The soil moisture control section is dry for one-half to three-fourths of the time when the soil temperature is above 41 degrees F.; dry for 70 to 85 consecutive days.
Mean summer soil temperature 59 to 66 degrees F.
Mean annual soil temperature - 41 to 47 degrees F.
Depth to basalt bedrock - 20 to 40 inches
Depth to calcic horizon - 3 to 20 inches
Particle-size control section - 20 to 27 percent total clay, 10 to 20 percent carbonate clay; carbonatic free clay is 5 to 18 percent. It averages less than 15 percent fine sand or coarser excluding the cobbles.
A horizon
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 3 or 4 dry or moist
Reaction - neutral to slightly alkaline
Bw horizon
Value - 3 to 5 moist
Chroma - 3 or 4 dry or moist
Texture - L, SIL
Clay content - 20 to 27 percent
Reaction - slightly to moderately alkaline
Bk1 horizon
Hue - 10YR, 2.5Y
Value - 7 or 8 dry, 6 or 7 moist
Chroma, dry - 1 through 3
Texture - L, SIL
Calcium carbonate content - 15 to 30 percent
2Bk2 horizon (when present)
Hue - 10YR, 2.5Y
Value - 7 or 8 dry, 6 or 7 moist
Chroma - 1 through 3 dry
Texture - CB-L, CBV-L
Rock fragments - 15 to 55 percent cobbles and 0 to 10 percent gravel
Calcium carbonate content - 15 to 30 percent
SAR - 5 to 13
COMPETING SERIES: These are the
Pancheri and
Polatis series. Pancheri soils are over 40 inches deep to bedrock.
Polatic soils have 8 to 18 percent total clay in the particle-size control section.
GEOGRAPHIC SETTING: Splittop soils are on basalt plains. Slopes range from 0 to 8 percent. Elevation ranges from 4,600 to 5,500 feet. The soil formed in eolian deposits reworked by water and residuum from basalt. The average annual precipitation is 11 to 13 inches, most of which falls as snow and early spring rains. The average annual temperature is 40 degrees to 45 degrees F. The frost free season is 70 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Atomic and Brunt soils. Atomic soils lack cambic horizons and are calcareous throughout and are on mounds. Brunt soils have natric horizons and occur in slick spots.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability.
USE AND VEGETATION: Mainly used for rangeland. Vegetation is Wyoming big sagebrush, bluebunch wheatgrass, basin wildrye, rabbit brush, and longleaf phlox.
DISTRIBUTION AND EXTENT: South central Idaho. The soil is of limited extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Blaine County, Idaho, 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon
Cambic horizon - the zone from 3 to 15 inches (Bw1 and Bw2 horizons)
Calcic horizon - the zone from 15 to 32 inches (Bk1 and Bk2 horizons)
Particle size control section - zone from 10 to 32 inches (Bw1, Bw2, Bk1 and Bk2 horizons). The cobbles are not included in the fine-earth particle-size class determination for coarse-silty only up to and including gravel.
ADDITIONAL DATA: Lab data from near type location S94ID-011-001.