LOCATION HARDHART                WY+MT

Established Series
Rec. PJL-KTS-EMM
12/2012

HARDHART SERIES

The Hardhart series consists of moderately deep, well drained soils that formed in colluvium and residuum derived from limestone. These soils are on hills, mountain slopes, ridges, dipslopes, scarp slopes, and structural benches. Slopes are 10 to 80 percent. The mean annual precipitation is about 19 inches, and the mean annual air temperature is about 41 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, carbonatic Ustic Calcicryolls

TYPICAL PEDON: Hardhart gravelly silt loam, in rangeland (colors are for dry soil unless otherwise stated).

A--0 to 8 inches; brown (10YR 4/3) gravelly silt loam, very dark grayish brown (10YR 3/2) moist; weak medium granular structure; soft, very friable, slightly sticky and slightly plastic; finely disseminated calcium carbonate; 30 percent gravel; slightly effervescent near fragments; neutral (pH 7.1) clear wavy boundary. (7 to 12 inches thick)

Bk1--8 to 17 inches; light yellowish brown (10YR 6/4) very gravelly loam, dark yellowish brown (10YR 4/4) moist; moderate coarse subangular blocky structure; slightly hard, very friable, moderately sticky and slightly plastic; many thick coatings and pendants of calcium carbonate on coarse fragments and disseminated calcium carbonate throughout the matrix; 45 percent gravel; violently effervescent; moderately alkaline (pH 7.9); clear smooth boundary. (5 to 14 inches thick)

Bk2--17 to 27 inches; very pale brown (10YR 7/3) very gravelly loam, brown (10YR 5/3) moist; moderate fine subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; violently effervescent, common soft masses, threads, and thick pendants of calcium carbonate on undersides of coarse fragments; 50 percent gravel; moderately alkaline (pH 7.9); abrupt irregular boundary. (6 to 17 inches thick)

R--27 inches; hard limestone, fractured in upper few inches with no displacement.

TYPE LOCATION: Sheridan County, Wyoming; SW1/4, NE1/4 of sec. 8,
T. 57 N., R. 88 W.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 36 to 42 degrees F.
Mean summer temperature: 51 to 57 degrees F.
Thickness of the mollic epipedon: 7 to 14 inches
Depth to a lithic contact: 20 to 40 inches

Particle size control section:
Clay content - average 15 to 27 percent
Texture (less than 2mm) - loam and silt loam
Rock fragments - average 35 to 75 percent

Note: These soils are typically calcareous to the surface, but may be leached a few inches in some pedons.

A horizon:
Hue - 10YR or 2.5Y; dry or moist
Value - 3 to 5 dry; 2 or 3 moist
Chroma - 1 to 3; dry or moist
Texture - loam or silt loam
Clay content - 15 to 27 percent
Rock fragments - 15 to 45 percent--15 to 45 percent gravel, 0 to 20 percent cobbles and stones
Calcium carbonate equivalent - 0 to 15 percent (includes coarse fragments less than the 20 mm fraction)
Reaction: pH 7.1 to 8.2

Bk horizons:
Hue - 10YR or 2.5Y; dry or moist
Value - 5 to 8 dry; 3 to 6 moist
Chroma - 2 to 4; dry or moist
Texture - loam or silt loam
Clay content - 15 to 27 percent
Rock fragments - 30 to 70 percent--25 to 60 percent gravel, 5 to 30 percent cobbles and stones
Calcium carbonate equivalent - 40 to 60 percent (includes coarse fragments less than the 20 mm fraction)
Reaction - pH 7.9 to 8.4

COMPETING SERIES:
Irrawaddy (CO) - have a cambic horizon
Nikat (MT) - is very deep
Pahreah (UT) - have hue of 5YR or 7.5YR in the Bk horizons

GEOGRAPHIC SETTING:
Landform - hills, mountain slopes, ridges, dipslopes, scarp slopes, and structural benches
Elevation - 4,860 to 7,800 feet
Slopes - 10 to 80 percent
Parent material - colluvium and residuum derived from limestone
Mean annual precipitation - 17 to 25 inches
Mean annual air temperature - 37 to 42 degrees F.
Frost-free season - less than 70 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Starley and Starman series. Both soils have bedrock at less than 20 inches. Starman soils also do not have mollic epipedon. Both soils also have less than 40 percent calcium carbonate equivalent in the control section.

DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.

USE AND VEGETATION: This soil is used for rangeland and wildlife habitat. Native vegetation consists of Idaho fescue, bluebunch wheatgrass, Oregon grape, common snowberry and scattered Douglas-fir, ponderosa and limber pine.

DISTRIBUTION AND EXTENT: North central Wyoming, and central and southwestern Montana. Hardhart soils are of small extent. MLRAs - 43B, 46.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.

SERIES ESTABLISHED: Sheridan County Area, Wyoming; 1985.

REMARKS: Diagnostic horizons and features recognized
Mollic epipedon - from 0 to 8 inches (A horizon)
Calcic horizon - from 8 to 27 inches (Bk1, Bk2 horizons)
Lithic contact at 27 inches - (R horizon)

The Hardhart soils have a cryic temperature regime and an ustic moisture regime.

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National Cooperative Soil Survey
U.S.A.