LOCATION WURSTEN IDEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Typic Calcixerolls
TYPICAL PEDON: Wursten gravelly silt loam - on a 15 percent northwest-facing slope at 4,680 feet elevation. (Colors are for dry soil unless otherwise noted. When described the soil was dry to 3 inches and moist below.)
A1--0 to 3 inches; grayish brown (10YR 5/2) gravelly silt loam, dark brown (10YR 3/3) moist; weak thin platy structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots, common medium and coarse roots; many very fine irregular and common very fine tubular pores; about 1 percent cobbles and 15 percent gravel; slightly effervescent; moderately alkaline (pH 8.2); abrupt smooth boundary. (2 to 7 inches thick)
A2--3 to 9 inches; grayish brown (10YR 5/2) gravelly silt loam, dark brown (10YR 3/3) moist; weak medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine, and common fine, medium, and coarse roots; many very fine tubular pores; about 15 percent gravel and 5 percent cobbles; slightly effervescent; moderately alkaline (pH 7.9); abrupt smooth boundary. (4 to 13 inches thick)
Bk1--9 to 22 inches; light gray (10YR 7/2) gravelly loam, pale brown (10YR 6/3) moist; weak medium and fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine and fine, and few medium and coarse roots; many very fine tubular pores; about 5 percent cobbles and 30 percent gravel; strongly effervescent; few thin lime coats on the undersides of rock fragments and around pores; moderately alkaline (pH 7.9); abrupt smooth boundary. (9 to 16 inches thick)
Bk2--22 to 33 inches; very pale brown (10YR 7/3) gravelly loam, pale brown (10YR 6/3) moist; weak medium and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine, and few medium roots; many very fine tubular pores; about 5 percent cobbles and 25 percent gravel; violently effervescent; few thin lime coats on undersides of rock fragments and around pores; moderately alkaline (pH 8.4); abrupt smooth boundary. (8 to 14 inches thick)
Bk3--33 to 39 inches; very pale brown (10YR 7/3) gravelly silt loam, brown (10YR 5/3) moist; weak medium and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and few fine roots; many very fine tubular pores; about 5 percent cobbles and 15 percent gravel; violently effervescent; few thin lime coats on the undersides of rock fragments and around pores; strongly alkaline (pH 8.8); clear smooth boundary. (4 to 9 inches thick)
Bk4--39 to 60 inches; very pale brown (10YR 7/3) gravelly silt loam, brown (10YR 4/3) moist; weak medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; many very fine tubular pores; about 5 percent cobbles and 15 percent gravel; strongly effervescent; strongly alkaline (pH 9.0).
TYPE LOCATION: Bannock County, Idaho; about 1.5 miles northwest of Virginia; about 500 feet north and 150 feet east of the southwest corner of section 5, T. 10 S., R. 37 E.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 43 to 46 degrees F.
Thickness of mollic epipedon and depth to calcic horizon - 8 to 18 inches
Particle size control section
Clay - 13 to 18 percent
Rock fragments - 10 to 35 percent
A or Ap horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Texture GR-SIL, SIL
Effervescence - slight or strong
Calcium carbonate equivalent - 5 to 15 percent
Reaction - slightly alkaline or moderately alkaline
Bk horizon
Value - 5 to 8 dry, 3 to 7 moist
Chroma, moist or dry - 2 to 4
Effervescence - strong or violent
Calcium carbonate equivalent - 10 to 30 percent
Reaction - moderately alkaline or strongly alkaline
Texture - GR-SIL, GR-L, GR-SL, GRV-SL, L
In some pedons there are more than 35 percent rock fragments below 40 inches.
COMPETING SERIES: This is the Ream (T) series. The Ream soils are 25 to 40 inches deep to a sandy-skeletal discontinuity and have redox concentrations or depletions at a depth of 48 to 60 inches.
GEOGRAPHIC SETTING: Wursten soils are on hills, fans, and terraces at elevations of 4,500 to 7,300 feet. Slopes are 0 to 40 percent. The soils formed in mixed alluvium, colluvium or slope alluvium. The mean annual temperature is 41 to 46 degrees F. The mean annual precipitation is 12 to 18 inches. The frost-free period is 70 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arbone, Arimo, Bear Lake, Downata, Downey, Hondoho, Inkom, Joevar, Ririe, and Watercanyon soils. Bear Lake, Downata, and Inkom soils are on stream terraces close to the valley floor where associated with Wursten. Hondoho and Arbone soils are mostly on north and east-facing slopes and in positions similar to Wursten but are more closely associated with higher broad fan terraces where the Joevar, Ririe, and Watercanyon soils are located. Downey and Arimo soils are on broad terraces above the Wursten soils. Arbone soils are not calcareous to the surface. Arimo and Downey soils are underlain by sandy-skeletal material. Bear Lake, Downata, and Inkom soils have an aquic moisture regime. Hondoho soils are loamy-skeletal. Joevar, Ririe, and Watercanyon soils are coarse-silty.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: These soils are used mainly for rangeland and dryland farming. Principal crops are alfalfa hay, wheat, and barley. Native vegetation is Wyoming big sagebrush, bluebunch wheatgrass, Nevada bluegrass, prairie junegrass, and Thurber needlegrass.
DISTRIBUTION AND EXTENT: Southeastern Idaho. Not extensive. MLRA 13, 28A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Bannock County, Idaho, 1983.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the soil surface to 9 inches (A1 and A2 horizons).
Calcic horizon - the zone from 9 to 39 inches (Bk1, Bk2, and Bk3 horizons).
Particle-size control section - The zone from 10 to 40 inches (Part of the Bk1, the Bk2, Bk3, and part of the Bk4 horizons).