LOCATION WORTMAN SDEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aridic Natrustolls
TYPICAL PEDON: Wortman loam - on a microhigh of less than 1 percent slope in native grass. When described the soil was moist to 35 inches. (Colors are for dry soil unless otherwise stated.)
A--0 to 4 inches; dark gray (10YR 4/1) loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, friable; slightly acid; abrupt smooth boundary. (0 to 8 inches thick)
E--4 to 6 inches; gray (10YR 5/1) loam, very dark gray (10YR 3/1) moist; weak thick platy structure parting to weak very fine granular; slightly hard, friable; slightly acid; abrupt irregular boundary. (1 to 5 inches thick)
Btn1--6 to 10 inches; dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; moderate medium columnar structure parting to strong fine and very fine blocky; extremely hard, firm, sticky and plastic; clay films on faces of peds; gray (10YR 5/1) coatings on tops of columns; slightly alkaline; clear smooth boundary. (2 to 6 inches thick)
Btn2--10 to 13 inches; brown (10YR 5/3) clay, dark brown (10YR 4/3) moist; weak medium prismatic structure parting to strong fine and very fine blocky; very hard, firm, sticky and plastic; clay films on faces of peds; few fine fragments of siltstone; moderately alkaline; clear wavy boundary. (3 to 9 inches thick)
Bk1--13 to 18 inches; pale brown (10YR 6/3) clay loam, brown (10YR 5/3) moist; weak coarse subangular blocky structure; hard, friable, slightly sticky; few fine fragments of siltstone; common fine accumulations of carbonate; strong effervescence; moderately alkaline; gradual wavy boundary. (4 to 10 inches thick)
Bk2--18 to 26 inches; very pale brown (10YR 7/3) loam, brown (10YR 5/3) moist; weak coarse subangular blocky structure; hard, friable, slightly sticky; common fine fragments of siltstone; common fine accumulations of carbonate; strong effervescence; moderately alkaline; gradual smooth boundary. (0 to 12 inches thick)
C--26 to 35 inches; very pale brown (10YR 7/3) loam, brown (10YR 5/3) moist; massive; hard, friable, slightly sticky; many fine fragments of siltstone; many fine and medium accumulations of carbonate; strong effervescence; strongly alkaline; clear wavy boundary.
Cr--35 to 60 inches; very pale brown (10YR 8/3) and white (10YR 8/2) weathered soft siltstone, light yellowish brown (10YR 6/4) moist; easily dug with hand tools; strong effervescence; moderately alkaline.
TYPE LOCATION: Todd County, South Dakota; 1 mile north and 1 1/2 miles east of Mission; 2340 feet west and 150 feet south of the northeast corner of sec. 34, T. 39 N., R. 28 W.
RANGE IN CHARACTERISTICS: The depth to the soft siltstone ranges from 20 to 40 inches. The bedrock contains glass shards and has a high ratio of CEC to clay. The mollic epipedon ranges from 7 to 15 inches thick and extends into the Bt horizon of most epipedons.
The A horizon has 10YR hue, value of 4 or 5 and 2 or 3 moist, and chroma of 1 or 2. It typically is loam, silt loam, or fine sandy loam, but some pedons are coarser textured when mantled by sandy eolian material. The A horizon ranges from slightly acid to slightly alkaline.
The E horizon has 10YR hue, value of 5 to 7 and 3 or 4 moist, and chroma of 1 or 2. It ranges from slightly acid to slightly alkaline.
The Btn horizon has 10YR hue, value of 4 or 5 and 3 or 4 moist, and chroma of 2 or 3. It typically is clay but some are clay loam, silty clay or silty clay loam averaging between 35 and 50 percent clay. SAR is greater than 13. It ranges from neutral to moderately alkaline.
The Bk horizon has hue of 2.5Y to 7.5YR, value of 5 to 7 and 4 to 6 moist and chroma of 2 to 4. It is clay loam, loam, silt loam, or silty clay loam. It has few to many accumulations of carbonates and some pedons have accumulations of gypsum and other salts. It is slightly or moderately alkaline.
The C horizon has hue of 2.5Y to 7.5YR, value of 5 to 8 and 4 to 6 moist, and chroma of 2 to 4. It is loam, silt loam, silty clay loam and ranges from slightly to strongly alkaline.
The Cr horizon has hue of 2.5Y to 5YR, value of 6 to 8 and 5 to 7 moist, and chroma of 1 to 6. It is soft siltstone and ranges from slightly alkaline to strongly alkaline.
COMPETING SERIES: This is the Beckton series in the same family. Beckton soils do not have bedrock between depths of 20 and 40 inches.
GEOGRAPHIC SETTING: Wortman soils are nearly level or gently sloping on upland fans, and flats. Surfaces are plane or slightly convex and microrelief commonly is evident. Slope gradients typically are less than 3 percent but range up to 9 percent. Wortman soils formed in residuum weathered from siltstone. Mean annual temperature ranges from 45 to 48 degrees F, and the mean annual precipitation ranges from 12 to 18 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Blackpipe, Goshen, Huggins, Kadoka, Kube, Mosher, Norrest, Shena, and Wanblee soils. Blackpipe, Huggins, Kadoka, Kube, Norrest, and Shena soils do not have a natric horizon and are on nearby uplands. Goshen soils do not have a natric horizon and are in swales. Mosher and Wanblee soils are on similar landscapes. Mosher soils do not have bedrock within a depth of 40 inches. Wanblee soils do not have a mollic epipedon.
DRAINAGE AND PERMEABILITY: Well or moderately well drained. Runoff is low to high depending on slope. Permeability is very slow.
USE AND VEGETATION: Mostly in native range. Alfalfa and winter wheat are the main crops in cultivated areas. The main grasses are western wheatgrass, green needlegrass, needleandthread, blue grama, and buffalograss.
DISTRIBUTION AND EXTENT: South-central and southwestern South Dakota. The Wortman soils are of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Tripp County, South Dakota, 1939.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface to a depth of about 10 inches (A, E, and Btn1 horizons); argillic horizon (natric) - the zone from a depth of about 6 to 13 inches (Btn1 and Btn2 horizons).