LOCATION REXBURG IDEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, frigid Calcic Haploxerolls
TYPICAL PEDON: Rexburg silt loam, grassland. (Colors are for dry soil unless otherwise noted.)
A--0 to 7 inches; dark grayish brown (10YR 4/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak very thin platy structure in upper 2 inches, weak very fine and fine granular structure in the lower part; soft, very friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine pores; neutral (pH 6.8); clear smooth boundary. (4 to 9 inches thick)
AB--7 to 12 inches; dark grayish brown (10YR 4/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak fine prismatic structure parting to weak medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine tubular pores; neutral (pH 7.0); clear smooth boundary. (4 to 10 inches thick)
Bw1--12 to 17 inches; grayish brown (10YR 5/2) silt loam, dark grayish brown (10YR 4/2) moist; weak medium prismatic structure parting to weak medium subangular blocky; hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine tubular pores; many uncoated silt grains on faces of peds; neutral (pH 6.9); gradual wavy boundary. (4 to 12 inches thick)
Bw2--17 to 25 inches; brown (10YR 5/3) silt loam, dark grayish brown (10YR 4/2) moist; moderate medium subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine and fine roots; many very fine tubular pores; many uncoated silt grains on faces of peds; neutral (pH 7.1); abrupt wavy boundary. (0 to 14 inches thick)
Bk1--25 to 40 inches; very pale brown (10YR 7/3) silt loam, brown (10YR 5/3) moist; moderate medium and coarse subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine and fine roots; common very fine tubular pores; common cicada krotovinas; violently effervescent; moderately alkaline (pH 8.1); gradual wavy boundary. (5 to 22 inches thick)
Bk2--40 to 50 inches; very pale brown (10YR 7/3) silt loam, brown (10YR 5/3) moist; weak medium and coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine tubular pores; few cicada krotovinas; violently effervescent; moderately alkaline (pH 8.2); diffuse wavy boundary. (8 to 22 inches thick)
C--50 to 75 inches; very pale brown (10YR 7/3) silt loam, brown (10YR 5/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine tubular pores; strongly effervescent; moderately alkaline (pH 8.3).
TYPE LOCATION: Bingham County, Idaho; about 22 miles east and 5 miles south of Blackfoot; 1,520 feet north and 1,320 feet east of the southwest corner of sec. 5, T.4S., R.39E.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 40 to 47 degrees F
Particle-size control section - 8 to 18 percent clay
Thickness of the mollic epipedon - 12 to 20 inches
Depth to the calcic horizon - 18 to 35 inches
A horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Reaction - slightly acid to mildly alkaline
Bw horizon
Value - 5 or 6 dry, 3 through 5 moist
Chroma - 2 or 3 dry or moist
Reaction - neutral to moderately alkaline
Bk horizon
Value - 6 through 8 dry, 4 through 6 moist
Chroma - 2 through 4 dry or moist
Reaction - slightly alkaline through strongly alkaline
Calcium carbonate equivalent - 15 to 30 percent
COMPETING SERIES: These are the Gird and Ririe series. Ririe soils lack a cambic horizon and the depth to calcic horizon of 7 to 16 inches. Gird soils have 5 to 10 percent calcium carbonate in the calcic horizon.
GEOGRAPHIC SETTING: Rexburg soils are on loess covered fan terraces, foothills, and basalt plains. Slopes are 0 to 60 percent. They formed in loess and silty alluvium derived from loess. The mean annual precipitation is 12 to 18 inches. The mean annual temperature is 39 to 46 degrees F. Frost-free season is 70 to 110 days. Elevation is 4,600 to 7,250 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bancroft, Lanoak, Newdale, and the competing Ririe series. Bancroft soils have an argillic horizon and are fine-silty. Lanoak soils are pachic and are fine-silty. Newdale soils have a calcic horizon within 18 inches of the surface. Bancroft and Lanoak soils are on north and east-facing slopes. Newdale and Ririe soils are on south-facing slopes when associated with Rexburg.
DRAINAGE AND PERMEABILITY: Well drained; runoff is slow to very rapid; permeability is moderate.
USE AND VEGETATION: This Rexburg soil is used mainly for nonirrigated and irrigated cropland. The potential natural vegetation is mainly mountain big sagebrush and bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: Southeastern Idaho. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Bingham County, Idaho, 1972.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the surface to 12 inches (A and AB horizons)
Cambic horizon - the zone from 12 to 25 inches (Bw1 and Bw2 horizons)
Calcic horizon - the zone from 25 to 50 inches (Bk1 and Bk2 horizons)
Particle-size control section - the zone from 10 to 40 inches (Part of the AB, the Bw1, Bw2 and Bk1 horizons).