LOCATION BROADHURST SDEstablished Series
TAXONOMIC CLASS: Very-fine, smectitic, acid, mesic Torrertic Ustorthents
TYPICAL PEDON: Broadhurst clay - in native grass. When described the soil was dry below 20 inches. (Colors are for dry soil unless otherwise stated.)
A--0 to 3 inches; light brownish gray (10YR 6/2) clay, very dark grayish brown (10YR 3/2) moist; weak thick platy structure; very hard, very firm, sticky and plastic; few roots; moderately acid; abrupt smooth boundary. (1 to 4 inches thick)
AC--3 to 16 inches; grayish brown (10YR 5/2) clay, dark grayish brown (10YR 4/2) moist; weak coarse blocky and subangular blocky structure; very hard, very firm, sticky and plastic; few roots; very strongly acid; gradual smooth boundary. (8 to 15 inches thick)
C--16 to 41 inches; grayish brown (10YR 5/2) and light brownish gray (10YR 6/2) clay; dark grayish brown (10YR 4/2) moist; massive; extremely hard, very firm, sticky and plastic; very strongly acid; clear smooth boundary.
Cz--41 to 60 inches; light brownish gray (10YR 6/2) clay, very dark grayish brown (10YR 3/2) crushing to dark grayish brown (10YR 4/2) moist; massive; hard, very firm, sticky and plastic; common fine fragments of shale; common fine nests of gypsum and other salts; very strongly acid.
TYPE LOCATION: Butte County, South Dakota; about 7 miles north and 7 miles west of Belle Fourche; 1400 feet west and 1880 feet north of the southeast corner of sec. 4, T. 9 N., R. 1 E.
RANGE IN CHARACTERISTICS: Colors throughout the soil are largely inherited from the parent rock. The control section averages between 60 and 70 percent clay. The soil has an Ustic moisture regime that borders on Aridic. Consistence is hard to extremely hard when dry and very firm when moist. When the soil is dry, cracks 1/2 to 1 inch wide and several feet long extend downward for 20 inches or more. The soil typically is very strongly acid but ranges from extremely acid to moderately acid.
A and AC horizons have hue of 10YR or 2.5Y, value of 5 or 6 and 3 or 4 moist, and chroma of 1 or 2.
The C horizon has hue of 10YR, 2.5Y, or 5Y; value of 5 or 6 and 3 or 4 moist; and chroma of 1 or 2. Few or common partially weathered very fine fragments of shale are in the C horizon in most pedons. Nests of gypsum and other salts are few or common in the lower part of the C horizon.
COMPETING SERIES: There are no other series in the family.
GEOGRAPHIC SETTING: Broadhurst soils are on colluvial fans and terraces. Slope gradients range from 0 to 15 percent. These soils formed in clayey material derived from acid shales. Mean annual air temperature ranges from 43 to 48 degrees F, and mean annual precipitation ranges from 15 to 18 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Demar, Graner, and Grummit soils. Demar soils have argillic horizons and are on similar positions as the Broadhurst soils. Graner soils are friable throughout and are on adjacent undulating to rolling uplands. Grummit soils have shale within depths of 20 inches and are on steeper parts of the landscape.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium to very high depending on slope. Permeability is very slow except after dry periods when the initial intake in cracks is rapid.
USE AND VEGETATION: Used primarily for rangeland. Native vegetation is western wheatgrass, green needlegrass, Montana wheatgrass, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Western South Dakota. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Butte County, South Dakota, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon: ochric epipedon - the zone from the surface of the soil to a depth of 13 inches (A and AC horizons). The soil has an Ustic moisture regime that borders on Aridic. It will be reclassified to the Torrertic subgroup when it is approved.