LOCATION ZUNHALL IDEstablished Series
TAXONOMIC CLASS: Fine-silty, carbonatic, frigid Aquic Calcixerolls
TYPICAL PEDON: Zunhall silt loam, grass. (Colors are for dry soil unless otherwise noted.)
Ak1--0 to 2 inches; gray (N 6/) grayish brown 2.5Y 5/2 crushed silt loam, very dark gray (N 3/) moist; weak thin platy structure that parts to strong fine and very fine granular structure; hard, friable, slightly sticky and slightly plastic; root mat; many very fine interstitial pores; very strongly calcareous; strongly alkaline (pH 9.0); abrupt smooth boundary. (0 to 3 inches thick)
Ak2--2 to 6 inches; gray (N 6/) silt loam, very dark gray (N 3/) moist; moderate thin platy structure that parts to moderate very fine subangular angular blocky and weak fine and very fine granular structure; hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; common very fine tubular pores; very strongly calcareous; very strongly alkaline (pH 9.2); clear smooth boundary. (3 to 6 inches thick)
ABk--6 to 17 inches; gray (N 6/) silt loam, dark gray (N 4/) moist; weak medium platy structure that parts to moderate fine and very fine granular structure; slightly hard, very friable, moderately sticky and moderately plastic; many very fine granular structure; slightly hard, very friable, sticky and plastic; many very fine and fine roots; many very fine tubular pores; very strongly calcareous; strongly alkaline (pH 8.9); clear wavy boundary. (2 to 12 inches thick)
Bk1--17 to 23 inches; light gray (N 7/) silty clay loam, gray (N 5/) moist weak very fine and fine granular structure; hard, very friable, moderately sticky and moderately plastic; many very fine and fine roots; many very fine tubular pores; very strongly calcareous; strongly alkaline (pH 8.5); clear wavy boundary. (4 to 10 inches thick)
Bk2--23 to 37 inches; light gray (N 7/) silty clay loam, gray (N 5/) moist; few fine distinct dark yellowish brown (10YR 3/4) moist redox concentrations; massive; hard, friable; moderately sticky and moderately plastic; very strongly calcareous, common 1 mm spots of lime; moderately alkaline (pH 8.4); gradual wavy boundary. (10 to 25 inches thick)
Bk3--37 to 46 inches; pale yellow (2.5Y 8/2) silty clay loam, light brownish gray (2.5Y 6/2) moist; few fine distinct yellowish brown (10YR 5/6) moist redox concentrations; massive; hard, friable, moderately sticky and moderately plastic; common very fine tubular pores; common indurated lime concretions up to 3 inches across; very strongly calcareous; moderately alkaline (pH 8.3); gardual wavy boundary. (0 to 12 inches thick)
Bk4--46 to 55 inches; pale yellow (2.5Y 8/2) silt loam, light brownish gray (2.5Y 6/2) moist; few fine distinct yellowish brown (10YR 5/6) moist redox concentrations; massive; hard, friable, moderately sticky and moderately plastic; common very fine tubular pores; many indurated and strongly cemented lime concretions up to 3 inches across; very strongly calcareous; moderately alkaline (pH 8.3).
TYPE LOCATION: Caribou County, Idaho; NE1/4 NE1/4 section 3, T.6S., R.38E.
RANGE IN CHARACTERISTICS: The soils are usually moist, but are dry for 45 to 60 consecutive days in late summer and early fall. Depth to redoximorphic features of faint and distinct concentrations is 20 to 30 inches. Depth to the calcic horizon is 16 to 30 inches; calcic horizon based on over 15 percent calcium carbonate and the presence of 5 percent or more identifiable secondary carbonates. The mollic epipedon is 7 to 12 inches thick.
The Ak horizon has hue of 2.5Y or 10YR, value of 5 to 6 dry, 3 moist, and chroma of 0 to 2. It has weak or moderate platy and weak to strong granular structure. It is moderately or strongly alkaline. SAR is 5 to 13. Calcium carbonate percent is 15 to 40. It has 3 to 5 percent organic matter.
The ABk horizon has hue of 2.5Y or 10YR, value of 5 or 6 dry, 3 or 4 moist, and chroma of 0 to 2. Calcium carbonate percent is 30 to 85. It has 1 to 3 percent organic matter. It is silt loam or silty clay loam.
The Bk horizon has hue of 2.5Y or 10YR, value of 6 to 8 dry, 4 to 6 moist and chroma of 0 to 2. It is silt loam or silty clay loam with 18 to 35 percent total clay and less than 15 percent particles coarser than very fine sand. It is typically massive in the lower part with the upper part being weak platy and weak very fine and fine granular. It is moderately or strongly alkaline. SAR is 5 to 13. Calcium carbonate percent is 30 to 85. It has few to many, indurated to strongly cemented carbonate concretions up to 3 inches in diameter below a depth of about 30 inches; above 30 inches carbonate accumulations are visible but are not cemented. Organic matter is 0 to 1 percent.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Zunhall soils are on bottomlands and low alluvial fans at elevations of 4,700 to 6,200 feet. Slopes are 0 to 3 percent. The soils formed in alluvium of mixed origin. The semiarid climate has a mean annual precipitation of 12 to 16 inches including 3 to 5 feet of snow and a mean frost free season of 85 to 110 days. The mean annual temperature is about 41 to 46 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Fury and Rexburg soils. Fury soils have a mollic epipedon thicker than 24 inches and are mostly noncalcareous. Rexburg soils are well drained and are noncalcareous to a depth of about 20 inches.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; moderate slow permeability; fluctuating water table at depths of 1.5 to 2.0 feet from March to April. Flooding is occasional from March to April.
USE AND VEGETATION: Used chiefly for grazing. Small areas are used for production of hay. The natural vegetation is mainly saltgrass, western wheatgrass, sedges, rushes, and tufted hairgrass.
DISTRIBUTION AND EXTENT: Southeastern Idaho. The soils are inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Caribou County, Idaho, 1973; Fort Hall Area, Idaho.
REMARKS: Diagnostic horizons and other features:
- Mollic epipedon - the upper 8 inches of the soil meets mollic epipedon criteria 3b
- Caqlcic horizon beginning at 23 inches (>15% and identifiable secondary carbonates)
- Redox concentrations at 23 inches
- May need to consider reclassification to coarse-silty. When this series was proposed and established, the carbonate clay may be included with particle-size class family.