LOCATION ROSSTON OK+TXEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Ustic Epiaquerts
TYPICAL PEDON: Rosston clay--native vegetation. (Colors are for dry soil unless otherwise stated.)
A--0 to 13 inches; dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) crushed, moist; weak medium subangular blocky structure; very hard, very firm; noneffervescent throughout; moderately alkaline; clear smooth boundary. (8 to 17 inches thick)
Bss1--13 to 31 inches; dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) broken face, moist; moderate medium angular blocky structure; very hard, very firm; few prominent discontinuous sand coats on faces of peds and few intersecting slickensides; few fine rounded iron-manganese concretions throughout; noneffervescent throughout; moderately alkaline; gradual smooth boundary. (9 to 18 inches thick)
Bss2--31 to 51 inches; gray (10YR 5/1) clay, dark gray (10YR 4/1) broken face, moist; moderate medium angular blocky structure; very hard, very firm; few prominent discontinuous sand coats on faces of peds and very few intersecting slickensides; few fine rounded iron-manganese concretions throughout; noneffervescent throughout; moderately alkaline; gradual smooth boundary. (11 to 20 inches thick)
C--51 to 80 inches; grayish brown (10YR 5/2) clay, dark grayish brown (10YR 4/2) broken face, moist; massive; very hard, very firm; many fine rounded iron-manganese concretions throughout; noneffervescent throughout; moderately alkaline.
TYPE LOCATION: Harper County, Oklahoma; From the intersection of US Highway 283 and U.S. Highway 64 west of Rosston; 1 mile west on U.S. Highway 64; 4 mile north on county road; 800 feet north and 400 feet west of the southeast corner of sec. 22, T. 28 N., R. 26 W. Latitude: 36 degrees 53 minutes 14.0 seconds N. Longitude: 99 degrees 58 minutes 55.0 seconds W.
RANGE IN CHARACTERISTICS: The solum is more than 40 inches thick. A zone between 10 to 20 inches of the mineral soil surface aquic conditions for some time in most years. One-half or more of the pedon has chroma of either 2 or less if redoximorphic features are present; or chroma of 1 or less. These soils are ponded for 1 to 6 months in most years. When dry, cracks 0.4 to 2 inches wide extend from the surface to a depth of 40 inches or more. Cracks open and close each year except during higher than normal rainfall years. The cracks remain open for 90 or more cumulative days during most years. Slickensides begin at a depth greater than 10 inches.
The A horizon has hue of 10YR or 2.5Y, value of 2 to 5, and chroma of 2 or less. Redoximorphic features range from none to common. Thickness of the A horizon varies with microrelief, and ranges from 8 to 17 inches. Texture is silty clay or clay. Reaction ranges from neutral to moderately alkaline.
The Bss horizons have hue of 10YR or 2.5Y, value of 3 to 6, and chroma of 2 or less. Redoximorphic features range from few to common. Texture is silty clay or clay. Fine iron-manganese concretions range from none to common. Reaction ranges from neutral to moderately alkaline.
The C horizon has hue of 7.5YR to 2.5Y, value of 3 to 7, and chroma of 2 or less. Some pedons have loamy fine sand or fine sandy loam textures below a depth of 40 inches.
COMPETING SERIES: This is the Ranco, Randall and Ustibuck series. Ranco and Randall soils are in slightly drier climates (MLRA 77C). In addition, Ranco soils have 40 to 50 percent clay and Randall soils have a solum greater than 80 inches in depth. The Ustibuck series has hue of 7.5YR or redder and occur in more moist climates (MLRA 84A) and are on floodplains.
GEOGRAPHIC SETTING: The Rosston soils are in depressions 3 to 10 feet below the surrounding plain and range in size from a few acres to more than 40 acres. Slopes are nearly level with concave surfaces. The soil formed in clayey lacustrine sediments. The mean annual temperature ranges from 57 to 62 degrees F. The mean annual precipitation ranges from 22 to 26 inches. Frost-free period is 180 to 210 days, and the elevation ranges from 2000 to 3000 feet. Thornthwaite annual P-E indices range from 32 to 36.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Abbie, Irene, Paloduro, and Texroy series. Abbie, Paloduro and Texroy soils have fine-loamy textural control sections and occur on slightly higher landscape positions. Irene soils have fine-silty textural control sections and occur on higher landscape positions. Abbie, Irene and Texroy soils have argillic horizons.
DRAINAGE AND PERMEABILITY: Poorly drained; Permeability is very slow; internal drainage is slow. Runoff is ponded or negligible.
USE AND VEGETATION: Native vegetation is sedges, Pennsylvania smartweed, cocklebur, and wooly leaf bursage.
DISTRIBUTION AND EXTENT: Southern High Plains Breaks (MLRA 77E) areas of Oklahoma, Kansas, and Texas. The series is of minor extent.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES PROPOSED: Harper County, Oklahoma; 1997.
REMARKS: Rosston soils were formerly mapped in the Randall series.
Diagnostic horizons and features recognized in this pedon are:
Episaturation - soil is saturated with water in one or more layers within 80 inches with one or more unsaturated layers with an upper boundary above 80 inches.
Aquic- periodic saturation and reduction.
Vertisol features: intersecting slickensides and wedge-shaped aggregates below the A horizon (8 to 40 inches). Deep wide cracks that are open 90 or more cumulative days in most years. Gilgai microrelief on undisturbed areas.
Redoximorphic features: Iron-manganese concentrations - zone of apparent accumulation of iron-manganese oxides. Iron-manganese depletions - zone of low chroma, 2 or less where iron-manganese oxides have been removed.