LOCATION AGAR SDEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Typic Argiustolls
TYPICAL PEDON: Agar silt loam - on a plane west-facing slope of 2 percent in native grass. When described the soil was dry throughout. (Colors are for dry soil unless otherwise stated.)
A--0 to 5 inches; dark gray (10YR 4/1) silt loam, very dark gray (10YR 3/1) moist; weak very fine granular structure; slightly hard, very friable; slightly acid; clear wavy boundary. (3 to 8 inches thick)
Bt1--5 to 8 inches; dark gray (10YR 4/1) crushing to dark grayish brown (10YR 4/2) silty clay loam, very dark gray (10YR 3/1) moist; weak medium prismatic structure parting to weak medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; shiny surfaces on faces of peds; neutral; clear wavy boundary.
Bt2--8 to 18 inches; dark grayish brown (10YR 4/2) silty clay loam, very dark grayish brown (10YR 3/2) crushing to dark grayish brown (10YR 4/2) moist; moderate medium prismatic structure parting to moderate medium and fine subangular blocky; hard, friable, slightly sticky and slightly plastic; shiny surfaces on faces of peds; neutral; clear smooth boundary. (Combined thickness of the B2t horizon is 8 to 18 inches.)
Bk1--18 to 22 inches; grayish brown (10YR 5/2) silty clay loam, dark grayish brown (10YR 4/2) moist; weak coarse prismatic structure parting to moderate medium and fine subangular blocky; hard, friable; few fine accumulations of carbonate; strong effervescence; slightly alkaline; clear wavy boundary.
Bk2--22 to 34 inches; light brownish gray (2.5Y 6/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; weak coarse prismatic structure parting to weak medium subangular blocky; hard, friable; common medium accumulations of carbonate; strong effervescence; moderately alkaline; gradual wavy boundary.
Bk3--34 to 40 inches; light brownish gray (2.5Y 6/2) silt loam, grayish brown (2.5Y 5/2) moist; weak medium subangular blocky structure; hard, friable; common medium accumulations of carbonate; strong effervescence; moderately alkaline; gradual wavy boundary. (Combined Bk horizon is 10 to 25 inches.)
C3--40 to 61 inches; light brownish gray (2.5Y 6/2) silt loam, dark grayish brown (2.5Y 4/2) moist; massive; slightly hard, friable; few fine and medium accumulations of carbonate; strong effervescence; moderately alkaline.
TYPE LOCATION: Sully County, South Dakota; about 15 miles west and 2 miles south of Agar; 2,290 feet east and 270 feet north of the southwest corner of sec. 32, T. 116 n., R. 79 W.
RANGE IN CHARACTERISTICS: Depth to carbonates ranges from 11 to 26 inches. Thickness of mollic epipedon ranges from 7 to 20 inches.
The A horizon has hue of 10YR, value of 4 or 5 and 2 or 3 moist, and chroma of 1 or 2. It is silt loam or silty clay loam. It is slightly acid or neutral.
The Bt horizon has hue of 10YR or 2.5Y, value of 4 or 5 and 3 or 4 moist, and chroma of 1 to 3. It is silty clay loam or silt loam averaging between 24 to 35 percent clay and contains less than 3 percent fine sand or coarser. It is neutral or slightly alkaline.
The Bk horizon has hue of 10YR, 2.5Y, or 5Y, value of 5 or 6 and 4 or 5 moist, and chroma of 2 or 3. It is silt loam or silty clay loam. It contains few to many masses or striations of accumulations of carbonate. It is slightly or moderately alkaline.
The C horizon has hue of 10YR, 2.5Y or 5Y, value of 5 to 7 and 4 or 5 moist, and chroma of 2 or 3. It is silt loam or silty clay loam and ranges from slightly to strongly alkaline. Clay loam till, stratified sand and silt or shale are at depths between 40 and 60 inches in some pedons.
COMPETING SERIES: These are the Eakin, Fairlo, Highmore, Holdredge, Monticello, Northdale, and Paka soils. Eakin soils have clay loam till within depths of 40 inches. Fairlo soils have silty clay material within depths of 24 and 38 inches. Highmore soils formed in silty drift and contain more sand and coarse fragments. Holdredge soils have higher soil temperatures and typically are deeper to carbonates. Monticello and Northdale soils have redder hue. Paka soils formed in materials from siltstone and contain more sand.
GEOGRAPHIC SETTING: The Agar soils are on nearly level to moderately sloping uplands. Surfaces are plane or convex and slope gradients range from 0 to 9 percent. The Agar soils formed in silty loess sediments ranging from 40 inches to as much as 20 feet in thickness. Mean annual temperature ranges from 45 to 50 degrees F. and mean annual precipitation ranges from 15 to 24 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Eakin and Highmore soils and the DeGrey, Glenham, Lowry, Mobridge, Onita, Raber, Sully, and Walke soils. Eakin soils are in similar landscapes where the silty mantle is less than 40 inches thick over glacial till. Highmore soils are on similar landscapes. DeGrey and Walke soils have natric horizons and are in slightly depressed areas. Glenham soils have a fine-loamy control section and formed in glacial till and are on similar landscapes. Lowry soils have a coarse-silty control section and do not have an argillic horizons and are on similar landscapes. Mobridge and Onita soils are in swales and have mollic epipedons greater than 20 inches thick. Raber soils have a fine textured control section and formed in firm, clay loam glacial till on slightly higher landscapes. Sully soils do not have mollic epipedons, have a coarse-silty control section, and typically are on steeper landscapes.
DRAINAGE AND PERMEABILITY: Well drained. Surface runoff is low on nearly level slopes and medium on more sloping areas. Permeability is moderate.
USE AND VEGETATION: The main crops are small grain, corn, and sorghums. Some areas are irrigated. Some areas are used as range. Native vegetation includes green needlegrass, western wheatgrass, needleandthread, blue grama, big bluestem, little bluestem, sedges, and forbs.
DISTRIBUTION AND EXTENT: Central South Dakota. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Potter County, South Dakota, 1955. Made inactive 6/65 and reactivated in Hughes County, 12/70.
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 18 inches (A, Bt1, Bt2 horizons); argillic horizon - the zone from about 5 to 18 inches (Bt1, Bt2 horizons.)
PHASE RECOGNIZED: Clay substratum. This phase is now included with the Fairlo series.