LOCATION STILL LAKE SDEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Calcic Hapludolls
TYPICAL PEDON: Still Lake silty clay loam on 4 percent slope in a cultivated field. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 18 centimeters (0 to 7 inches); black (10YR 2/1) silty clay loam, dark gray (10YR 4/1) dry; moderate fine and medium subangular blocky structure parting to moderate fine and medium granular; slightly hard, friable; slightly sticky and slightly plastic; 5 percent worm casts and worm holes; common medium and many fine and very fine roots; common very fine and fine and few medium pores; slightly acid; abrupt smooth boundary. [A horizon thickness is 15 to 25 centimeters (6 to 10 inches)]
Bw1--18 to 36 centimeters (7 to 14 inches); very dark brown (10YR 2/2) silty clay loam, dark grayish brown (10YR 4/2) dry; moderate fine and medium prismatic structure parting to moderate fine and medium subangular blocky; slightly hard, friable; slightly sticky and slightly plastic; 20 percent worm casts and worm holes; few medium and common fine and very fine roots; common very fine and few fine pores; neutral; clear smooth boundary.
Bw2--36 to 58 centimeters (14 to 23 inches); brown (10YR 4/3) silty clay loam, brown (10YR 5/3) dry; moderate fine and medium prismatic structure parting to moderate fine and medium subangular blocky; slightly hard, friable; slightly sticky and slightly plastic; 15 percent worm casts and worm holes; few medium and common fine and very fine roots; common very fine and few fine pores; slightly alkaline; abrupt smooth boundary. [Combined thickness of the Bw horizon 20 to 71 centimeters (8 to 28 inches)]
Bk1--58 to 94 centimeters (23 to 37 inches); olive brown (2.5Y 4/4) silt loam, light yellowish brown (2.5Y 6/4) dry; moderate medium and coarse prismatic structure; slightly hard, friable; 5 percent worm casts and worm holes; few fine and common very fine roots; common very fine pores; 15 percent calcium carbonate equivalent; common fine and medium carbonate masses; violent effervescence; moderately alkaline; gradual wavy boundary.
Bk2--94 to 137 centimeters (37 to 54 inches); olive brown (2.5Y 4/3) silt loam, light yellowish brown (2.5Y 6/3) dry; few fine prominent gray (10YR 6/1) redoximorphic depletions; moderate medium and coarse prismatic structure; slightly hard, friable; few fine and common very fine roots; common very fine pores; 17 percent calcium carbonate equivalent; common fine and medium accumulations of calcium carbonate; violent effervescence; moderately alkaline; clear wavy boundary. [Combined thickness of the Bk horizon 25 to 114 centimeters (10 to 45 inches)]
2Bk3--137 to 178 centimeters (54 to 70 inches); light olive brown (2.5Y 5/4) clay loam, light yellowish brown (2.5Y 6/4) dry; common fine and medium prominent gray (10YR 6/1) redoximorphic depletions and few fine distinct yellowish brown (10YR5/4) redoximorphic concentrations; weak coarse prismatic structure; hard, firm, slightly sticky and slightly plastic; few very fine roots; few very fine pores; 18 percent calcium carbonate equivalent; 5 percent gravel; common fine and medium carbonate masses; violent effervescence; moderately alkaline; gradual wavy boundary. [2Bk horizon thickness is 15 to 64 centimeters (6 to 25 inches)]
2C--178 to 203 centimeters (70 to 80 inches); olive brown (2.5Y 4/4) clay loam, light yellowish brown (2.5Y 6/4) dry; common fine and medium distinct gray (10YR 6/1) redoximorphic depletions and common fine and medium distinct yellowish brown (10YR 5/4) redoximorphic concentrations; massive; hard, firm, slightly sticky and slightly plastic; 14 percent calcium carbonate equivalent; 5 percent gravel; few fine accumulations of calcium carbonate; strong effervescence; moderately alkaline;
TYPE LOCATION: Codington County, South Dakota; about 3 miles south and 5 miles east of Florence; 499 meters (1,635 feet) west and 87 meters (285 feet) north of the southeast corner of section 20, T. 118 N., R. 53 W. USGS Still Lake, S. Dak. topographical quadrangle; latitude 45 degrees 0 minutes 27.4 seconds N. and longitude 97 degrees 12 minutes 54.1 seconds W., NAD83.
RANGE IN CHARACTERISTICS: The thickness of the mollic epipedon ranges from 18 to 41 centimeters (7 to 16 inches). The depth to calcium carbonates ranges from 38 to 91 centimeters (15 to 36 inches). The particle size control section averages between 24 and 32 percent clay. The depth to glacial till ranges from 102 to 152 centimeters (40 to 60 inches). A coarse textured layer 3 to 8 centimeters (1 to 3 inches) in thickness is at the glacial till contact in some pedons. Most pedons have fine or medium redoximorphic features within 127 centimeters (50 inches).
The A horizon has value of 2 or 3 and 3 or 4 dry and chroma of 1. It typically is silty clay loam but is silt loam in some pedons. Reaction is slightly acid or neutral.
The Bw horizon has hue of 10YR or 2.5Y, value of 2 to 4 and 4 to 6 dry, and chroma of 1 to 4. It typically is silty clay loam but is silt loam in some pedons. Reaction is slightly acid or neutral in the upper part and neutral or slightly alkaline in the lower part.
The Bk horizon has hue of 2.5Y or 10YR, value of 4 to 6 and 5 to 7 dry, and chroma of 2 to 4. It is silty clay loam or silt loam. It has common or many accumulations of carbonates. Reaction is slightly alkaline or moderately alkaline.
The 2Bk horizon has hue of 2.5Y or 10YR, value of 4 to 6 and 5 to 7 dry, and chroma of 2 to 4. It is clay loam. It has common or many accumulations of carbonates. Some pedons contain diagonal wedges up to 8 centimeters (3 inches) in width of sandy material. Reaction is slightly alkaline or moderately alkaline.
The 2C horizon has hue of 10YR or 2.5Y, value of 4 to 6 and 5 to 7 dry, and chroma of 2 to 4. It is clay loam. Some pedons contain diagonal wedges up to 8 centimeters (3 inches) in width of sandy material. Reaction is slightly alkaline or moderately alkaline.
COMPETING SERIES: These are the Brandt, Great Bend, Kings Lake, Kranzburg, Poinsett, and Putney series. Brandt soils have a 2C horizon with more than 15 percent gravel. Great Bend soils are varved with thin layers of sand to clay at a depth of 102 to 152 centimeters (40 to 60 inches). Varves range from less than 1 mm to 10 mm in thickness. Kings Lake and Kranzburg soils have glacial till between depths of 51 and 102 centimeters (20 and 40 inches). The Kings Lake and Poinsett soils also have strata in the horizon above the glacial till. Strata ranges in texture from loam to silty clay loam and are 10 mm to 50 mm in thickness. Putney soils have gypsum and other salts within depths of 51 centimeters (20 inches).
GEOGRAPHIC SETTING: Still Lake soils are nearly level to gently sloping on uplands having plane to convex slopes with gradients of 0 to 6 percent. The soils are formed in calcareous loess deposits overlying loamy glacial till. Mean annual air temperature ranges from 4 to 7 degrees C (38 to 45 degrees F), and mean annual precipitation ranges from 485 to 735 millimeters (19 to 29 inches). Growing season is about 120 to 160 days; average growing season precipitation ranges from 330 to 457 millimeters (13 to 18 inches); and growing degree days are about 2500 to 3000.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Badger, Graceland, and Kranzburg soils. The somewhat poorly drained Badger soils have a fine textured control section and are in the deeper swales. The moderately well drained Graceland soils have mollic epipedons more than 41 centimeters (16 inches) thick and are on footslopes and in swales. The well drained Kranzburg soils have glacial till between 51 and 102 centimeters (20 and 40 inches) and are on similar landscape positions as the Still Lake soils.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained. Surface runoff is low or medium. Saturarted hydraulic conductivity, measured in cm per hour, is 1.52 to 5.10 (.6 to 2.0 inches) in the upper loess mantle and .51 to 1.52 (.2 to .6 inches) in the underlying glacial till. Occasional saturation occurs within 102 to 152 centimeters (40 to 60) inches during the months April through June in years of above normal precipitation. In years with normal precipitation, saturation typically does not occur for periods of 1 month or more within 152 centimeters (60 inches).
USE AND VEGETATION: Most areas of Still Lake are cultivated; the principal crops are corn, soybeans, small grains, and alfalfa. Native vegetation includes: big bluestem, little bluestem, green needlegrass, switchgrass, forbs, and sedges.
DISTRIBUTION AND EXTENT: MLRA-102A. Northeastern South Dakota. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Codington County, South Dakota, 2006
REMARKS: Diagnostic horizons and textures recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 36 centimeters (14 inches) (Ap and Bw1 horizons); cambic horizon - the zone from 18 to 58 centimeters (14 to 23 inches) (Bw2 horizon): calcic horizon - the zone from 58 to 178 centimeters (23 to 70 inches) (Bk1, Bk2, and 2Bk3)
This series was separated from the Poinsett series. The upper mantle of this series is loess derived and the upper mantle in the Poinsett series is silty drift.