LOCATION FAIRLO SDEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Typic Argiustolls
TYPICAL PEDON: Fairlo silt loam on a northeast-facing slope of 4 percent in native grass. When described the soil was moist to 9 inches. (Colors are for dry soil unless otherwise stated).
A1--0 to 4 inches; dark grayish brown (10YR 4/2) silt loam, black (10YR 2/1) moist; weak fine subangular blocky structure parting to weak fine granular; slightly hard, very friable; many fine roots; slightly acid; clear smooth boundary.
A2--4 to 9 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; weak fine prismatic structure parting to weak medium and fine subangular blocky; slightly hard, very friable; many very fine and fine roots; slightly acid; clear wavy boundary. (Combined thickness of the A horizons is 6 to 10 inches.)
Bt1--9 to 14 inches; grayish brown (10YR 4/3) silty clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium prismatic structure parting to moderate coarse and medium subangular blocky; hard, friable, slightly sticky and slightly plastic; common fine and very fine roots; shiny surfaces on the faces of the peds; neutral; gradual smooth boundary.
Bt2--14 to 18 inches; brown (10YR 5/3) silty clay loam, dark brown (10YR 3/3) moist; moderate medium prismatic structure parting to moderate coarse and medium subangular blocky; hard, friable; common fine and very fine roots; slightly sticky and slightly plastic; shiny surfaces on the faces of the peds; slightly alkaline; abrupt smooth boundary. (Combined thickness of the Bt horizons is 8 to 14 inches.)
Bk1--18 to 24 inches; pale brown (10YR 6/3) silty clay loam, dark brown (10YR 4/3) moist; moderate medium prismatic structure parting to weak moderate subangular blocky; hard, friable, slightly sticky and slightly plastic; few fine and very fine roots; common fine accumulations of carbonate; strong effervescence; moderately alkaline; clear wavy boundary.
Bk2--24 to 29 inches; pale brown (10YR 6/3) silty clay loam, dark brown (10YR 4/3) moist weak coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine roots; common fine accumulations of carbonate; strong effervescence; moderately alkaline; clear wavy boundary. (Combined thickness of the Bk horizons ranges from 10 to 14 inches.)
2Bk3--29 to 55 inches; light brownish gray (2.5Y 6/2) silty clay, dark grayish brown (2.5Y 4/2) moist; weak coarse subangular blocky structure; very hard, firm, sticky and plastic; many medium and coarse accumulations of carbonate; strong effervescence; moderately alkaline; gradual wavy boundary.
2Bk4--55 to 60 inches; light brownish gray (2.5Y 6/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; weak coarse subangular blocky structure; very hard, friable, slightly sticky and plastic; common medium accumulations of carbonate; strong effervescence; moderately alkaline.
TYPE LOCATION: Lyman County, South Dakota about 11 miles north and 2 miles east of Kennebec; 1,175 feet north and 100 feet west of the southeast corner of sec. 9, T. 107 N., R. 75 W.
RANGE IN CHARACTERISTICS: Depth to carbonates ranges from 14 to 24 inches. The thickness of the mollic epipedon ranges from 7 to 19 inches. Depth to clayey sediments is typically from 26 to 35 inches but ranges from 24 to 38 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 2 to 4 moist, chroma of 2 to 4. It is typically silty clay loam but is silt loam in some pedons. The estimated clay percentages range from 26 to 35 percent. It ranges from slightly acid to slightly alkaline.
The Bk horizon has hue of 10YR or 2.5Y, value of 5 to 7 and 4 to 5 moist, and chroma of 2 to 4. It is silt loam or silty clay loam. It is slightly or moderately alkaline.
The 2Bk horizon has 2.5Y or 10YR hue, value of 5 to 7 and 4 or 5 moist, and chroma of 2 to 4. It is silty clay loam, silty clay, or clay. The clay content ranges from 35 to 55 percent, but typically contains more than 40 percent clay.
Some pedons have a 2C horizon of similar color and textures as the Bk horizon.
COMPETING SERIES: These are the Agar, Eakin, Highmore, Holdredge, Monticello, Northdale, and Paka soils of the same family. Agar, Eakin, Highmore, and Holdredge soils do not have fine textures at depths of 24 to 38 inches. In addition, Eakin soils are underlain by glacial till and Holdredge soils formed in deep loess. Monticello and Northdale soils contain more very fine sand and have redder hues. In addition, Northdale soils have bedrock within depths of 20 and 40 inches. Paka soils have soft siltstone at depths of 40 to 60 inches.
GEOGRAPHIC SETTING: The Fairlo soils are on nearly level to moderately sloping uplands. Surfaces are plane or convex, and slopes range from 0 to 9 percent. They formed in silty material overlying clayey sediments. Mean annual temperature ranges from 45 to 50 degrees F, and the mean annual precipitation ranges from 15 to 24 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Agar soils and the Carter, Dorna, Hurley, McClure, Millboro, Mobridge, and Onita soils. Agar, Dorna, and McClure soils are on similar landscapes. Dorna soils do not have an argillic horizon. McClure soils have a fine textured argillic horizon. Carter soils have more clay in the series control section and are in the lower parts of the landscape. Hurley soils have a natric horizon and are in slightly depressed areas (microrelief). Millboro soils are on nearly similar landscapes and they have fine-textured argillic horizons. Mobridge and Onita soils are in swales and have mollic epipedons greater than 20 inches thick. In addition, Onita soils have fine-textured argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained. Surface runoff is low on nearly level slopes and medium on more sloping areas. Permeability is moderate in the silty part of the soils and slow in the underlying clayey sediments.
USE AND VEGETATION: About equally divided between native range and cropland. Small grain, sorghum, corn, and alfalfa are the principal crops. Native vegetation includes green needlegrass, western wheatgrass, needleandthread, blue grama, sideoats grama, bluestems, sedges, and forbs.
DISTRIBUTION OF EXTENT: South-central South Dakota. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Lyman County, South Dakota, 1984.
REMARKS: In adjoining Stanley County,South Dakota, these soils were correlated as Agar silt loam, clayey substratum.
Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of about 9 inches (A horizon); argillic horizon - the zone from about 9 to 18 inches (Bt1 and Btz horizons).