LOCATION GRAT SDEstablished Series
TAXONOMIC CLASS: Clayey over sandy or sandy-skeletal, smectitic, mesic Typic Argiaquolls
TYPICAL PEDON: Grat loam - on a plane slope of less than 1 percent in native grass. (When described the soil was dry to 31 inches and moist below. Colors are for moist soil unless otherwise stated.)
A1--0 to 3 inches; black (10YR 2/1) loam, dark gray (10YR 4/1) dry; weak medium subangular blocky and moderate medium granular structure; slightly hard, friable; neutral; gradual smooth boundary.
A2--3 to 5 inches; black (10YR 2/1) loam, dark gray (10YR 4/1) dry; weak medium platy structure parting to moderate fine and medium granular; slightly hard, friable, slightly sticky and slightly plastic; neutral; gradual wavy boundary. (Combined A horizons 3 to 10 inches thick)
Bt--5 to 8 inches; very dark gray (10YR 3/1) clay loam, dark gray (10YR 4/1) dry; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, firm, sticky and plastic; few fine accumulations of carbonate; slight effervescence; neutral; gradual wavy boundary.
Btk--8 to 14 inches; dark gray (10YR 4/1) clay loam, gray (10YR 5/1) dry; few fine prominent dark yellowish brown (10YR 4/6)redox concentrations; moderate medium prismatic structure parting to moderate and strong medium subangular blocky; hard, firm, sticky and plastic; few fine dark concretions (oxides); disseminated and common fine accumulations of carbonate; strong effervescence (8 percent calcium carbonate); moderately alkaline; gradual wavy boundary. (Combined Bt horizons 5 to 30 inches thick)
Bkg1--14 to 20 inches; dark gray (5Y 4/1) clay loam, gray (5Y 5/1) dry; common fine prominent strong brown (7.5YR 5/6) and light olive brown (2.5Y 5/4) redox concentrations; moderate medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common fine dark concretions (oxides); disseminated and common medium accumulations of carbonate; strong effervescence (12 percent calcium carbonate); moderately alkaline; gradual wavy boundary.
Bkg2--20 to 31 inches; light brownish gray (2.5Y 6/2) clay loam, white (2.5Y 8/2) dry; massive; hard, friable, slightly sticky and slightly plastic; few medium dark concretions (oxides); violent effervescence (40 percent calcium carbonate); moderately alkaline; abrupt wavy boundary. (Combined Bk horizons 0 to 25 inches thick)
2Cg--31 to 55 inches; grayish brown (2.5Y 5/2) stratified sand and gravel, light brownish gray (2.5Y 6/2) dry; many fine and medium distinct strong brown (7.5YR 5/6) redox concentrations; single grained; loose; common fine dark concretions (oxides); slight effervescence; slightly alkaline; abrupt wavy boundary.
3Cg--55 to 60 inches; olive gray (5Y 5/2) clay loam, light gray (5Y 7/2) dry; many medium distinct strong brown (7.5YR 5/6) and yellowish brown (10YR 5/6) redox concentrations; massive; hard, friable, slightly sticky and slightly plastic; common fine dark concretions (oxides); strong effervescence; slightly alkaline.
TYPE LOCATION: Beadle County, South Dakota; about 7 miles south and 4.5 miles west of Huron; 2230 feet east and 80 feet south of the northwest corner of sec. 9, T. 109 N., R. 62 W.
RANGE IN CHARACTERISTICS: Thickness of the mollic epipedon ranges from 7 to 40 inches and commonly includes part or all of the Bt horizon. Depth to carbonates ranges from 3 to 40 inches. Few or common nests of gypsum and other salts are in the Bk horizon above the sand and gravel in some pedons.
The A horizon has value of 2 or 3 and 3 to 5 dry, and chroma of 1 or 2. It typically is loam or clay loam and less commonly silt loam. It is slightly acid or neutral.
The Bt horizon has hue of 10YR or 2.5Y, value of 3 to 5 and 4 to 6 dry, and chroma of 1 or 2. It is clay loam, clay or silty clay loam with an estimated 35 to 50 percent clay content. The Bt horizon commonly has accumulations of carbonate in the lower part. Dark coatings of A material commonly are on the faces of peds. It is hard, or very hard when dry and firm when moist. Redox features are not present in the lower part of the Bt horizon in some pedons. Reaction is neutral to moderately alkaline.
The Bk horizon has hue of 2.5Y or 5Y, value of 4 to 6 and 5 to 8 dry, and chroma of 1 to 4. It is clay loam, clay, silty clay loam or silty clay. It is slightly alkaline or moderately alkaline. Few or common distinct or prominent redox features are in the Bk horizon. Some pedons have a 2Bk, C or Cg horizons.
The 2C horizon of sand and gravel commonly is below depths of 30 inches but ranges from 20 to 40 inches.
The 3C horizon of clay loam, loam or silty clay loam commonly is below the sand and gravel between depths of 50 and 60 inches. Some pedons so not have a 3C horizon. The 2C and 3C horizons are slightly alkaline or moderately alkaline.
COMPETING SERIES: There are no other series in the same family.
GEOGRAPHIC SETTING: These soils are on level or nearly level flood plains and in swales on outwash plains. Slope gradients are 0 to 2 percent. Surfaces are plane or slightly concave. These soils formed in clayey alluvium overlying sand and gravel. The mean annual air temperature ranges from 45 to 50 degrees and the mean annual precipitation ranges from 17 to 23 inches. Growing season is about 125 to 155 days; average growing season precipitation from 14 to 18 inches; and growing degree days are about 2800 to 3400.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Davis, Delmont, Durrstein, Egas and Enet soils. The Davis, Delmont and Enet soils are fine-loamy and are on higher nearby landscapes. Durrstein soils have a natric horizon and Egas soils have visible salt accumulations at depths less than 7 inches. Both are in similar landscapes and in places within areas of Grat soils.
DRAINAGE AND PERMEABILITY: Poorly drained. Surface runoff is negligible to medium depending on slope. Permeability is slow in the solum and rapid in the underlying sand and gravel. These soils flood for short periods after heavy rainfall. A seasonal water table is at depths of 0 to 2 feet in the spring of most years.
USE AND VEGETATION: Most areas of Grat soils are in native grass. Native vegetation includes big bluestem, switchgrass, Indian grass, western wheatgrass, sedges and forbs. Small grain, corn, and alfalfa are principal crops in the few cultivated areas.
DISTRIBUTION AND EXTENT: East-central South Dakota. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Beadle County, South Dakota, 1976.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 8 inches (A1, A2 and Bt horizons); argillic horizon - the zone from 5 to 14 inches (Bt and Btk horizons); calcic horizon - the zone from 20 to 31 inches (Bkg2 horizon).