LOCATION WHITEKNOB IDEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, mixed, frigid Xeric Haplocalcids
TYPICAL PEDON: Whiteknob loam, rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 5 inches; light brownish gray (10YR 6/2) loam, dark grayish brown (10YR 4/2) moist; weak thin platy structure parting to moderate fine granular; soft, friable, slightly sticky and slightly plastic; common very fine and fine roots; many fine and very fine vesicular pores; strongly effervescent; strongly alkaline (pH 8.5); abrupt smooth boundary. (2 to 10 inches thick)
Bw--5 to 10 inches; light brownish gray (10YR 6/2) loam, dark grayish brown (10YR 4/2) moist; moderate fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine, common fine and few medium roots; many very fine and common fine tubular pores; strongly effervescent; moderately alkaline (pH 8.2); abrupt wavy boundary. (0 to 10 inches thick)
2Bk1--10 to 18 inches; light gray (10YR 7/2) extremely gravelly sandy loam, grayish brown (10YR 5/2) moist; single grain; loose; nonsticky and nonplastic; many very fine, common fine and few medium roots; many fine and medium interstitial pores; about 90 percent gravel; moderately thick lime coatings on the lower side of the gravel and thin coatings on the upper side; violently effervescent; moderately alkaline (pH 8.3); clear wavy boundary. (6 to 9 inches thick)
2Bk2--18 to 60 inches; gray (10YR 6/1) extremely gravelly sand, dark gray (10YR 4/1) moist; single grain; loose; common very fine roots; many fine and medium interstitial pores; about 90 percent gravel; gravel slightly lime coated on lower side; strongly effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Butte County, Idaho; about 15 miles northwest of Howe; 200 feet west of State Highway 22; 2,310 feet south and 1,320 feet west of the northeast corner of section 25, T.8N., R.27E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 41 to 45 degrees F., and the mean summer soil temperature is 59 to 63 degrees F. The soils are usually dry, but are moist between depths of 12 and 35 inches for about 70 to 85 consecutive days in the spring. The depth to the calcic horizon is 10 to 15 inches. Depth to contrasting sand and gravel (2Bk horizon) is 10 to 25 inches. The particle-size control section has 35 to 90 percent coarse fragments with the upper 10 inches having 45 to 70 percent sand and 5 to 10 percent clay and the lower 20 inches having 80 to 95 percent sand and 3 to 8 percent clay.
The A horizon has value of 5 or 6 dry, 3 or 4 moist, and chroma of 2 or 3 moist and dry. It has granular or platy structure and has 0 to 50 percent gravel. Reaction is slightly alkaline to strongly alkaline.
Calcium carbonate equivalent is 10 to 20 percent.
The Bw horizon has hue of 10YR or 2.5Y, value of 5 or 6 dry, 3 through 6 moist, and chroma of 2 to 4 moist and dry. It has weak and moderate subangular blocky structure. Reaction is slightly alkaline to strongly alkaline. It is loam or gravelly loam with 10 to 18 percent clay and 0 to 35 percent gravel. Calcium carbonate equivalent is 10 to 20 percent.
The 2Bk1 or 2Bkq1 horizon has value of 6 or 7 dry, 5 or 6 moist, and chroma of 2 or 3. Reaction is moderately or strongly alkaline. Calcium carbonate equivalent is 15 to 30 percent. It is very gravelly or extremely gravelly sandy loam or loam with 5 to 10 percent clay and 35 to 90 percent cobbles and gravel.
The 2Bk2 or 2Bkq2 horizon is very gravelly or extremely gravelly sand or loamy coarse sand with 3 to 8 percent clay and 50 to 90 percent cobbles and gravel. Reaction is moderately or strongly alkaline. Calcium carbonate equivalent is 15 to 35 percent.
COMPETING SERIES: This is the Leadore series. Leadore soils are not calcareous to the soil surface.
GEOGRAPHIC SETTING: Whiteknob soils are on outwash fans and fan terraces at elevations of 4,800 to 6,700 feet. Slopes are 0 to 12 percent. The soils formed in mixed alluvium. The mean annual precipitation is 7 to 11 inches including 0.5 to 1.5 feet of snow. The mean annual air temperature is 38 to 45 degrees F. The frost free season is 65 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Medicine Lodge and Blackfoot soils. Medicine Lodge soils have more than 18 percent clay in the upper part of the 10 to 40 inch control section. Blackfoot soils occupy bottomlands and are somewhat poorly drained.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; slow to medium runoff; moderate permeability in the upper part and very rapid in the lower part.
USE AND VEGETATION: Used for production of pasture, hay and small grains. Vegetation is mainly Wyoming big sagebrush, Indian ricegrass, needleandthread, shadscale, fourwing saltbush and bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: Southeastern Idaho. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Jefferson County, Idaho, 1975.
REMARKS: Diagnostic horizon and other features:
Ochric epipedon
Calcic horizon - 10 to 18 inches
Particle-size control section - 10 to 40 inches; the upper part from 10 to 18 inches has 5 percent clay with 70 percent sand, the lower part from 18 to 40 inches has 5 percent clay with 90 percent sand.