LOCATION DANKO WYEstablished Series
TAXONOMIC CLASS: Clayey, smectitic, calcareous, mesic, shallow Ustic Torriorthents
TYPIFYING PEDON: Danko clay, grassland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 2 inches; brown (7.5YR 5/4) clay; dark brown (7.5YR 4/4) moist; moderate medium fine granular structure; slightly hard, friable, very plastic; calcareous; very strongly alkaline (pH 9.0); abrupt smooth boundary. (2 to 3 inches thick)
C--2 to 12 inches; reddish-brown (5YR 5/4) clay, reddish-brown (5YR 4/4) moist; massive; extremely hard, very firm, very plastic; calcareous; very strongly alkaline (pH 9.5); gradual wavy boundary. (8 to 17 inches thick)
IIC--12 to 60 inches; calcareous, reddish-brown strongly alkaline shale bedrock.
TYPE LOCATION: Johnson County, Wyoming. Near the center of sec. 22, T.45N., R.80W.
RANGE IN CHARACTERISTICS: Depth to shale bedrock ranges from 10 to 20 inches. Weighed average organic carbon content of the surface 15 inches is typically .8 percent and sand/clay ration is 1 or less. Conductivity typically ranges from less than 1 to 4 millimhos, and exchangeable sodium percentage ranges from 15 to 30 percent. Cation exchange capacity ranges from 70 to 100 milliequivalents per 100 grams of clay. The control section is typically a clay but clay may range from 40 to 55 percent, silt from 10 to 50 percent, and sand from 10 to 40 percent. Content of coarse fragments ranges from 0 to 15 percent but is typically less than 5 percent. Mean annual soil temperature ranges from 47 degrees F. to 58 degrees F., and mean summer soil temperature from 59 degrees F. to 78 degrees F. The A horizon has hue of 7.5Y or 5YR, value is 4 or 5 dry or moist, and chroma is 3 or 4. Primary structure is generally granular but is subangular blocky in some pedons. This horizon is soft to slightly hard and strongly to very strongly alkaline. The hue of the C horizon ranges from 5YR through 2.5YR.
COMPETING SERIES AND THEIR DIFFERENTIAE: These are the Gilger, Lismas, Midway, Orella, and Samsil series. The Gilger soils have hues of 7.5YR or yellower throughout and are strongly saline. The Lismas, Midway, and Samsil soils have hues no redder than 7.5YR and have exchangeable sodium percentage of less than 15. The Orella soils have hue no redder than 7.5YR throughout the profile.
SETTING: These soils occur on moderately to steeply sloping upland hills and ridges where reddish colored strongly alkaline shales are exposed. Gradients range from 2 to 15 percent or more. The soils are developing fine textured highly alkaline sediments weathered residually from reddish-colored bedrock. At the type location the average annual precipitation is 14 inches, with peak periods of precipitation during the spring and early summer months. Mean annual soil temperature is 48 degrees F., mean summer soil temperature is 67 degrees F., mean annual air temperature is 46 degrees F., and mean summer air temperature is 66 degrees F.
PRINCIPAL ASSOCIATED SOILS: These include the Barnum and the competing Orella series. The Barnum soils lack bedrock above 40 inches and are much loess alkaline.
DRAINAGE AND PERMEABILITY: Well-drained. Runoff is rapid, permeability is very slow.
USE AND VEGETATION: These soils are used principally as native pastureland. Typically, 50 to 80 percent of the areas are barren and native vegetation is limited to species tolerant of strong degrees of alkalinity.
DISTRIBUTION AND EXTENT: Present known distribution limited to north central Wyoming. The series is of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Johnson County (Southern Johnson Area), Wyoming, 1971.