LOCATION HIGHMORE SDEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Typic Argiustolls
TYPICAL PEDON: Highmore silt loam in a fallowed field on a slightly convex slope of 1 percent. When described the soil was moist throughout. (Colors are for dry conditions unless otherwise stated.)
Ap--0 to 7 inches; dark gray (10YR 4/1) silt loam, black (10YR 2/1) moist; weak medium granular structure; soft, very friable; neutral; abrupt smooth boundary. (5 to 8 inches thick)
Bt1--7 to 12 inches; dark grayish brown (10YR 4/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; weak medium prismatic structure parting to moderate medium subangular blocky; hard, friable, slightly sticky and slightly plastic; shiny coats on faces of peds; neutral; clear smooth boundary.
Bt2--12 to 17 inches; grayish brown (10YR 5/2) silty clay loam, dark grayish brown (10YR 4/2) moist; weak medium prismatic structure parting to weak medium subangular blocky; hard, friable, slightly sticky and slightly plastic; shiny coats on faces of peds; slightly alkaline; clear wavy boundary. (Combined Bt horizons is 7 to 20 inches thick.)
Bk1--17 to 25 inches; light yellowish brown (2.5Y 6/3) silty clay loam, light olive brown (2.5Y 5/3) moist; weak coarse prismatic structure parting to weak coarse subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; common medium and fine accumulations of carbonate; strong effervescence; moderately alkaline; gradual wavy boundary.
Bk2--25 to 40 inches; light yellowish brown (2.5Y 6/3) silt loam, light olive brown (2.5Y 5/3) moist; weak coarse subangular blocky structure; slightly hard, friable; common medium accumulations of carbonate; strong effervescence; moderately alkaline; gradual wavy boundary. (Combined Bk horizons is 6 to 35 inches thick.)
C1--40 to 49 inches; light yellowish brown (2.5Y 6/3) silt loam, light olive brown (2.5Y 5/3) moist; massive; slightly hard, friable; few fine accumulations and few medium concretions of carbonate; strong effervescence; moderately alkaline; clear smooth boundary.
C2--49 to 60 inches; light yellowish brown (2.5Y 6/3) silt loam, light olive brown (2.5Y 5/3) moist; common light gray (2.5Y 7/1) mottles; massive; slightly hard, friable; few fine accumulations of carbonate; strong effervescence; moderately alkaline.
TYPE LOCATION: Sully County, South Dakota, about 3 1/2 miles south and 2 miles east of Onida; l555 feet north and 80 feet east of the southwest corner of sec. 30, T. 114 N., R. 76 W.
RANGE IN CHARACTERISTICS: The mollic epipedon ranges from 9 to 20 inches in thickness and extends into the Bt horizon in most pedons. The solum has up to 5 percent by volume granitic pebbles in some pedons. Scattered boulders are on the surface or embedded in the soil of some pedons. The depth to carbonate typically is about 17 inches but ranges from 12 to 26 inches.
The A horizon has value of 3 to 5 and 2 or 3 moist, and chroma of 1 or 2. It is slightly acid or neutral.
The Bt horizon has hue of 10YR or 2.5Y, value of 4 or 5 and 2 to 4 moist, and chroma of 2 or 3. It averages between 27 and 35 percent clay and between 3 and 15 percent sand that is coarser than very fine sand. It is neutral or slightly alkaline. Some pedons have Btk horizons.
The Bk horizon has hue of 10YR or 2.5Y, value of 5 to 7 and 4 to 6 moist, and chroma of 2 or 4. It is silty clay loam or silt loam. It is slightly alkaline or moderately alkaline. Accumulations of carbonate range from few to many, fine to coarse and extend into the C horizon.
The C horizon has hue of 10YR or 2.5Y, value of 5 to 7 and 4 to 6 moist, and chroma of 2 to 4. It is silty clay loam, silt loam, or very fine sandy loam. It is slightly alkaline or moderately alkaline. Mottles are in most pedons in the lower part and vary considerably in amount, size, and contrast. Thin layers of stratified sediments are common in the lower C horizon in some pedons.
2C horizons are at depths of 40 to more than 60 inches in some pedons and consist of loam or clay loam glacial till.
COMPETING SERIES: These are the Agar, Eakin, Fairlo, Holdrege, Monticello, Northdale, and Paka series. Agar soils formed in loess and have less sand that is coarser than very fine than the Highmore soils. Eakin soils have glacial till between depths of 20 and 40 inches. Fairlo soils are underlain by clayey sediments. Holdrege soils have thicker A horizons and are leached of carbonates to greater depths. Monticello and Northdale soils have redder hue. Paka soils formed mainly in residuum weathered from siltstone.
GEOGRAPHIC SETTING: Highmore soils are on nearly level to undulating uplands. Slopes are plane to convex and range from 0 to 9 percent, but commonly are less than 2 percent. Highmore soils formed in silty glacial drift. Mean annual temperature ranges from 45 to 48 degrees F, and mean annual precipitation ranges from about 17 to 21 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Eakin soils and the DeGrey, Glenham, Mobridge, Onita, Raber, and Walke soils. Eakin, Glenham, and Raber soils are intermingled with Highmore soils on the more undulating landscapes. Glenham soils are fine-loamy and Raber soils are fine. DeGrey and Walke soils have a natric horizon and are on flats that are slightly lower than the Highmore soils. Mobridge and Onita soils have mollic epipedons more than 20 inches thick and are on footslopes.
DRAINAGE AND PERMEABILITY: Well drained. Surface runoff is slow on nearly level landscapes and medium on more sloping areas. Permeability is moderate.
USE AND VEGETATION: Mainly cultivated. Winter wheat, alfalfa, corn, grain sorghum, and oats are the main crops. Native grasses are mainly western wheatgrass, needleandthread, green needlegrass, big bluestem, and blue grama.
DISTRIBUTION AND EXTENT: Mainly in central and south-central South Dakota east of the Missouri River. Highmore soils are extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Hughes County, South Dakota, 1970.
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 12 inches (Ap & Bt1 horizons); argillic horizon - the zone from about 7 to 17 inches (Bt1 & Bt2 horizons).