LOCATION SPEARMAN MT+WYEstablished Series
TAXONOMIC CLASS: Fine-loamy over fragmental, mixed, superactive, mesic Aridic Haplustolls
TYPICAL PEDON: Spearman loam - native. (Colors are for dry soil unless otherwise noted.)
A11--0 to 2 inches; reddish brown (5YR 5/3) heavy loam, dark reddish brown (5YR 3/3) moist; moderate thin platy structure; slightly hard, very friable, slightly sticky, slightly plastic; many very fine roots and interstitial pores; neutral; clear smooth boundary.
A12--2 to 4 inches; reddish brown (5YR 5/3) light clay loam, dark reddish brown (5YR 3/3) moist; weak medium prismatic structure; slightly hard, friable, slightly sticky, slightly plastic; many very fine roots; many very fine and fine tubular pores; neutral; clear wavy boundary. (Al horizon 4 to 7 inches thick)
B2--4 to 15 inches; reddish brown (5YR 5/4) light clay loam, dark reddish brown (5YR 3/4) moist; moderate medium prismatic structure that separates to moderate medium blocks; hard, friable, slightly sticky, slightly plastic; many very fine roots; many very fine and few fine tubular pores; few red burned shale fragments; neutral; gradual wavy boundary. (8 to 16 inches thick)
C1--15 to 19 inches; light reddish brown (5YR 6/4) channery loam, yellowish red (5YR 4/6) moist; weak fine blocky structure; hard, friable, slightly sticky, slightly plastic; many very fine roots, common very fine and few fine tubular pores; 15 percent flat burned shale fragments; mildly alkaline; clear wavy boundary. (3 to 10 inches thick)
C2--19 to 23 inches; light reddish brown (5YR 6/5) loam, yellowish red (5YR 4/5) moist, massive; hard, friable, slightly sticky, slightly plastic; many very fine roots; common very fine and few fine tubular pores; 30 percent flat burned shale fragments; moderately calcareous with lime crust on underside of shale fragments; moderately alkaline; abrupt wavy boundary.
C3--23 to 60 inches; fragmented hard red burned shale with roots matted between shale layers in upper 2 inches.
TYPE LOCATION: Big Horn County, Montana; 550 feet east and 600 feet north of S1/4 corner section 1, T.1S., R.37E.
RANGE IN CHARACTERISTICS: Spearman soils are usually dry, but their upper horizons are occasionally moistened by summer rains of one or more inches intensity. Mean annual soil temperature is 48 to 50 degrees F. The hue is 7.5YR through 10R. The mollic epipedon is 7 to 15 inches thick. Depth to hard platy shale is 20 to 40 inches. Shale fragments throughout the A and B horizons range from 2 to 10 percent and throughout the C horizons overlying bedded shale range from 10 to 50 percent, but the average volume of coarse fragments from 10 inches to the hard platy shale is less than 35 percent. The A1 horizon has value of 2 or 3 moist and chroma of 2 through 4, with chroma of 4 occurring below 4 inches. The B horizon has value of 5 or 6, 3 or 4 moist and chroma of 4 through 6. It is heavy loam or light clay loam with estimated 2 to 5 percent more clay than in the A1 or Ap horizons.
COMPETING SERIES: These are the tentative Capps, Deacon, Fishers and Shirk series and the established Nucla, Ortiz and Searing series. Capps, Deacon and Fishers soils lack paralithic contacts at depths of 40 inches or less. Also, Fishers soils are noncalcareous throughout. Nucla and Shirk soils have hue of 10YR or 2.5Y and the Nucla soils are very deep. Ortiz soils are calcareous throughout the solum and have a Cca horizon. Searing soils have dry value of 4 in the Al horizon, are usually moist and have mean annual soil temperature of 39 to 47 degrees F.
GEOGRAPHIC SETTING: Spearman soils are on nearly level to rolling uplands. The soils farmed in loamy materials weathered from underlying hard red burned shales. The climate is cool, moist semiarid with mean annual temperature of 45 to 50 degrees F., and mean annual precipitation of 12 to 16 inches, 70 percent of which falls during April through September.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chugter and Wibaux soils. Chugter soils are deep over platy hard shale beds and Wibaux soils are shallow over platy hard shale beds and they have ochric epipedons.
DRAINAGE AND PERMEABILITY: Well-drained; slow or medium runoff; moderate or moderately rapid permeability.
USE AND VEGETATION: Use is mainly for range. Grasses are needle-and-thread grass, green needle grass, western wheat grass and Japanese brome grass.
DISTRIBUTION AND EXTENT: Widely distributed in southeastern Montana and northeastern Wyoming. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Big Horn County (Big Horn Area), Montana, 1970.
REMARKS: Spearman soils were formerly classified as Brown soils.
OSED scanned by SSQA. Last revised by state on 5/71.