LOCATION SHENA SDEstablished Series
TAXONOMIC CLASS: Clayey, smectitic, mesic, shallow Aridic Argiustolls
TYPICAL PEDON: Shena silt loam - on a southeast-facing convex slope of 5 percent under native grass. When described the soil was moist to 12 inches. (Colors are for dry soil unless otherwise stated.)
A--0 to 4 inches; dark gray (10YR 4/1) silt loam, very dark gray (10YR 3/1) moist; weak medium subangular blocky structure parting to weak medium and fine granular; slightly hard, friable; neutral; clear smooth boundary. (3 to 5 inches thick)
Bt1--4 to 8 inches; dark grayish brown (10YR 4/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; weak medium and fine prismatic structure parting to moderate fine subangular blocky; very hard, firm, slightly sticky and plastic; patchy clay films on faces of peds; few pale brown (10YR 6/3) soft siltstone fragments 1 to 3 mm in diameter; neutral; clear smooth boundary. (3 to 6 inches thick)
Bt2--8 to 12 inches; brown (10YR 5/3) silty clay loam, dark brown (10YR 4/3) moist; weak medium blocky structure parting to moderate fine subangular blocky; hard, firm, slightly sticky and plastic; 25 percent by volume pale brown (10YR 6/3) and very pale brown (10YR 7/3) soft siltstone fragments, 2 to 5 mm in size; neutral; clear wavy boundary. (2 to 6 inches thick)
Cr--12 to 60 inches; very pale brown (10YR 7/3) siltstone bedrock, brown (7.5YR 5/4) moist; siltstone is difficult to chip with a spade; mildly alkaline.
TYPE LOCATION: Todd County, South Dakota; about 9 miles east and 5 miles north of Mission; 125 feet east and 1188 feet south of the northwest corner of sec. 12, T. 39 N., T. 27 W.
RANGE IN CHARACTERISTICS: Depth to bedrock ranges from 8 to 17 inches. It is neutral or slightly alkaline throughout. The mollic epipedon is 7 to 12 inches thick and extends into the Bt horizon.
The A horizon has 10YR hue, value of 4 or 5 and 2 or 3 moist, and chroma of 1 or 2. It is silt loam or silty clay loam.
The Bt1 horizon has 10YR hue, values of 4 or 5 and 2 or 3 moist, and chroma of 2 or 3. It is silty clay loam or silty clay averaging between 35 and 45 percent clay. A few siltstone fragments ranging from 1 to 5 mm in size are scattered throughout.
The Bt2 horizon has 10YR or 7.5YR hue, value of 4 or 5 and 3 or 4 moist, and chroma of 2 or 3. It is silty clay loam, clay loam, or silty clay. Siltstone fragments range from 2 to 15 mm in size and 15 to 35 percent by volume. The fragments are coated with organic stains.
The Cr horizon has hue of 10YR or 7.5YR, value of 5 to 8 and 4 to 6 moist, and chroma of 2 to 4. It is slightly alkaline or moderately alkaline. The siltstone has strata of different hardness. Some strata contain free carbonate.
COMPETING SERIES: There are no other series in the same family.
GEOGRAPHIC SETTING: Nearly level to moderately steep uplands with slope gradients ranging from 0 to 15 percent. Surfaces are slightly convex. Shena soils formed in thin clayey residuum weathered from siltstone. The mean annual temperature is 45 to 50 degrees F, and precipitation ranges from 14 to 18 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Epping,
Huggins,
Kadoka,
Wanblee, and
Wortman soils. Epping, Huggins, and Kadoka soils are on similar landscapes.
Epping soils do not have a mollic epipedon and are loamy. Huggins and Kadoka have silt stone at a depth greater than 20 inches. Wanblee and Wortman soils have a natric horizon and are on nearly level landscapes with micro-relief.
DRAINAGE AND PERMEABILITY: Well drained. Surface runoff is medium or high on lower slopes and very high on steeper slopes. Permeability is moderately slow in the material above the bedrock and very slow below.
USE AND VEGETATION: Most areas are used for rangeland. Western wheatgrass, blue grama, and sedges are the main grasses.
DISTRIBUTION AND EXTENT: South-central South Dakota. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Tripp County, South Dakota, 1975.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of about 8 inches (A and Bt1 horizons); argillic horizon - the zone from a depth of about 4 to 12 inches (Bt1 and Bt2 horizons).