LOCATION LOHSMAN WYEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Haplic Ustic Natrargids
TYPICAL PEDON: Lohsman fine sandy loam-grassland. (Colors are for dry soil unless otherwise stated.)
E--0 to 4 inches; light gray (10YR 7/2) fine sandy loam, grayish brown (10YR 5/2) moist; weak medium platy structure that parts to moderate fine granules; soft, very friable; neutral (pH 6.6); abrupt smooth boundary. (0 to 6 inches thick)
Bt--4 to 9 inches; brown (10YR 5/3) clay, dark brown (10YR 4/3) moist; strong medium columnar structure that parts to strong medium angular blocky; extremely hard, very sticky, very friable, very plastic; continuous moderately thick clay films on faces of peds and lining of pores and root channels; slightly effervescent, lime disseminated; moderately alkaline (pH 8.4); gradual wavy boundary. (4 to 8 inches thick)
Btn--9 to 13 inches; brown (10YR 5/3) clay, dark brown (10YR 4/3) moist; moderate medium prismatic structure that parts to strong medium angular blocks; extremely hard, very friable, very sticky and very plastic; continuous moderately thick clay films on faces of peds and lining of pores and root channels; slightly effervescent, lime disseminated; very strongly alkaline (pH 9.2); gradual wavy boundary. (4 to 8 inches thick)
Btnky--13 to 18 inches; light olive brown (2.5Y 5/3) heavy clay loam, olive brown (2.5Y 4/3) moist; moderate medium angular blocky structure; very hard, friable, very sticky and very plastic; few thin clay films on faces of peds, common moderately thick linings in root channels; violently effervescent, common segregations of medium soft masses and filaments; few medium gypsum crystals; very strongly alkaline (pH 9.2); gradual wavy boundary. (0 to 8 inches thick)
Bky--18 to 26 inches; light olive brown (2.5Y 5/4) clay loam, olive brown (2.5Y 4/4) moist; massive; hard, very friable, sticky, plastic; violently effervescent, common soft masses of lime; common medium gypsum crystals; very strongly alkaline (pH 9.2); gradual wavy boundary. (6 to 25 inches thick)
Cr--26 inches; calcareous, very strongly alkaline gray shale.
TYPE LOCATION: Johnson County; NW1/4, SE1/4 of sec. 31, T. 45 N., R. 79 W.
RANGE IN CHARACTERISTICS: Depth to calcareous material ranges from 6 to 15 inches. The depth to the base of the natric horizon ranges from 10 to 20 inches. Depth to the paralithic contact ranges from 20 to 40 inches. The weighted average organic carbon content of the surface 15 inches is approximately 0.6 percent. Sand/clay ratio is usually less than 1. Exchangeable sodium percentage is 4 to 12 in the upper part of the Bt but ranges from 15 to 30 in the Btn. Soft shale chips range from 0 to 15 percent but are typically less than 2 percent. In some pedons thin A horizons are present, and in other pedons the E horizon is absent due to erosion. The soil is dry in the moisture control section more than half the time cumulative that the soil temperature at a
depth of 20 inches is 41 degrees F. and is never moist in some or all parts for as long as 60 consecutive days when the soil temperature at a depth of 20 inches is 41 degrees F., which occurs about April 21-27, but is dry in all parts of the moisture control section for at least 60 consecutive days from July 15 to October 25 and for at least 90 cumulative days during this period. The mean annual soil temperature is 47 to 53 degrees F., and the soil temperature at a depth of 20 inches is 41 degrees F. or more for 175 to 192 days.
The E horizon has hue of 2.5Y or 10YR, value of 6 or 7 dry, 5 or 6 moist, and chroma of 2 or 3. It usually has platy primary structure but has grandular or subangular blocky structure in some pedons. This horizon is soft and slightly hard. Reaction is neutral or mildly alkaline. It is usually noncalcareous but is weakly calcareous in some pedons.
The Bt and Btn horizons have hue of 2.5Y or 10YR, value of 5 or 6 dry, 4 or 5 moist, and chroma of 2 through 4. They are typically clay or heavy clay loam and have 35 to 50 percent clay, 15 to 45 percent silt, and 10 to 45 percent sand with more than 15 percent but less than 35 percent fine sand or coarser. They usually have columnar primary structure but have prismatic or angular blocky structure in some pedons. Oriented clay films occur in some parts of these horizons. These horizons have less than 15 percent exchangeable sodium
in the upper part but have 15 to 30 percent in the lower part. They are moderately to very strongly alkaline. The Btnky horizon, when present, has 15 to 30 percent exchangeable sodium.
The Bky horizon has hue of 5Y through 10YR, value of 5 through 7 dry, 4 through 7 moist, and chroma of 2 through 4. It is strongly or very strongly alkaline and has 4 to 12 percent calcium carbonate equivalent. Texture is a clay loam. Salts more soluble than gypsum are not uncommon in this horizon or those immediately overlying this horizon.
COMPETING SERIES: These are the Absted, Allentine, Deertrail, and Gilt Edge series. These soils lack a paralithic contact at a depth of less than 40 inches. Also, Allentine and Gilt Edge soils have natric horizons with less than 15 percent exchangeable sodium but more sodium plus magnesium than calcium plus exchange acidity.
GEOGRAPHIC SETTING: The Lohsman soils are on gently sloping to rolling upland hills and ridges in areas where sedimentary bedrocks occur moderately close to the surface. Slopes usually range from 0 to 15 percent. These soils formed in moderately deep, very strongly alkaline, calcareous slopewash alluvium and residuum from shale. Elevations are 4,500 to 6,000 feet. The average annual precipitation is 12 inches with over half the annual precipitation falling in April, May, and June and less than one inch falling in each month of July, August, September, and October. Precipitation ranges from 10 to 14 inches. The mean annual temperature is about 45 degrees F. but ranges from 43 to 51 degrees F. The frost-free season is about 110 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Briggsdale, Renohill, and Wyarno soils. All of these soils lack natric horizons.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; slow permeability.
USE AND VEGETATION: These soils are used principally as native pastureland. Principal native vegetation is western wheatgrass, blue grama, and big sagebrush. Areas of these soils are usually characterized by numerous barren spots.
DISTRIBUTION AND EXTENT: Northern and central Wyoming. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Johnson County (Southern Johnson Area), Wyoming; 1971.