LOCATION NIHILL WY+MT NE SDEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, calcareous, mesic Ustic Torriorthents
TYPICAL PEDON: Nihill gravelly loam-rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 5 inches; dark brown (10YR 4/3) gravelly loam, very dark grayish brown (10YR 3/2) moist; weak very fine granular structure; soft, very friable, nonsticky and nonplastic; common fine and very fine roots; strongly effervescent, calcium carbonate disseminated and as thin crusts on some rock fragments; 20 percent pebbles; slightly alkaline (pH 7.4); clear wavy boundary. (0 to 7 inches thick)
Bk1--5 to 29 inches; light yellowish brown (10YR 6/4) very gravelly clay loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; violently effervescent, calcium carbonate and as few thin and moderately thick coatings on some rock fragments; 60 percent pebbles; moderately alkaline (pH 8.4); diffuse wavy boundary. (10 to 30 inches thick)
Bk2--29 to 60 inches; very pale brown (10YR 7/3) very gravelly sandy clay loam, light yellowish brown (10YR 6/4) moist; massive; slightly hard, friable, slightly sticky and nonplastic; violently effervescent, calcium carbonate as few thin discontinuous crusts on rock fragments; 60 percent pebbles; moderately alkaline (pH 8.3).
TYPE LOCATION: Sheridan County, Wyoming; in the SE1/4, SW1/4 of sec. 32, T. 57 N., R. 86 W. Dayton South Quadrangle 44 degrees 51 minutes 57 seconds north latitude
and 107 degrees 16 minutes 7 seconds west longitude.
RANGE IN CHARACTERISTICS: The Nihill soils typically contain free carbonates throughout but are leached free of carbonates in the upper few inches in some pedons. The mean annual soil temperature ranges from 47 to 54 degrees F. The particle-size control section has a matrix texture of clay loam, sandy clay loam, or sandy loam with 15 to 35 percent clay. Rock fragments, typically rounded pebbles, range from 35 to 70 percent. There is typically less than 5 percent larger than 3 inches.
The A horizon has hue of 10YR or 2.5Y, value of 4 through 6 dry, 3 through 5 moist, and chroma of 2 through 4. Rock fragments range from 10 to 45 percent pebbles and 0 to 5 percent cobbles. It is slightly alkaline or moderately alkaline.
The Bk or C horizons have hue of 10YR or 2.5Y, value of 5 through 8 dry, 4 through 7 moist, and chroma of 2 through 4. Rock fragments range from 35 to 70 percent pebbles and 0 to 5 percent cobbles. Calcium carbonate equivalent ranges from 2 to 14 percent. It is slightly alkaline through strongly alkaline.
COMPETING SERIES: This is the Chilton series which has hue of 7.5YR or 5YR in the control section.
GEOGRAPHIC SETTING: Nihill soils are on late Pleistocene terraces and terrace remnants. They formed in calcareous gravelly alluvium from mixed sources. Slopes are 0 to 80 percent. Elevations range from 2,600 to 6,800 feet. The mean annual precipitation is about 16 inches but ranges from 10 to 19 inches with about half falling as snow or rain in April, May, and early June. The mean annual temperature is about 46 degrees F., but ranges from 44 to 50 degrees F. The frost-free season is estimated to range from 105 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Butche, Hesper, Keiser, Shingle, and Wanetta series. Butche soils have a lithic contact at less than 20 inches. Hesper, Keiser, and Wanetta soils have argillic horizons and are nonskeletal. Shingle soils are shallow to weakly consolidated bedrock.
DRAINAGE AND PERMEABILITY: Well drained to somewhat excessively drained; medium to high runoff depending upon slope; moderate permeability.
USE AND VEGETATION: Rangeland and wildlife habitat. Native vegetation consists of western wheatgrass, needleandthread, blue grama, and in some areas bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: North central and eastern Wyoming, South Dakota, and Colorado. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Treasure County, Montana; 1961.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 5 inches (A)
MLRR- G
SIR's- WY0136, WY0431, WY1267
The type location is moved from Montana to Wyoming as per agreement reached in 1981.