LOCATION SIOUX SD+MN NDEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, mixed, frigid Entic Hapludolls
TYPICAL PEDON: Sioux gravelly loam on a convex slope of 7 percent in native grassland. (Colors are for dry soil unless otherwise stated)
A--0 to 6 inches; black (10YR 2/1) gravelly loam, dark gray (10YR 4/1) dry; weak fine granular structure; slightly hard, friable; many very fine roots; few very fine tubular pores; about 18 percent mixed rock fragments; slightly alkaline; clear smooth boundary. (4 to 10 inches thick)
ABk--6 to 9 inches; very dark grayish brown (10YR 3/2) gravelly sandy loam, grayish brown (10YR 5/2) dry; weak fine granular structure; soft, very friable; common very fine roots; about 9 percent calcium carbonate equivalent; about 30 percent mixed rock fragments; strong effervescence; moderately alkaline; clear smooth boundary. (0 to 6 inches thick)
BCk--9 to 19 inches; dark grayish brown (2.5Y 4/2) very gravelly loamy sand, light brownish gray (2.5Y 6/2) dry; single grain; loose; few very fine roots; few carbonate coats are on the undersides of pebbles in the upper part; about 13 percent calcium carbonate equivalent; about 50 percent mixed rock fragments; strong effervescence; moderately alkaline; gradual wavy boundary. (0 to 20 inches thick)
C--19 to 80 inches; olive brown (2.5Y 4/3) very gravelly sand, light yellowish brown (2.5Y 6/3) dry; single grain; loose; about 11 percent calcium carbonate equivalent; about 55 percent mixed rock fragments; strong effervescence; moderately alkaline.
TYPE LOCATION: Codington County, South Dakota, about 5 miles south and 3 miles east of Florence; about 1,310 feet south and 285 feet east of the northwest corner, section 6, T. 117 N., R. 53 W; USGS WATERTOWN WEST, S. DAK. quadrangle, latitude 44 degrees 58 minutes 27 seconds N, longitude 97 degrees 14 minutes 53 seconds W, NAD83.
RANGE IN CHARACTERISTICS: The depth to sandy-skeletal material ranges from 6 to 14 inches. Typically, the depth to carbonates ranges from 3 to 10 inches, but some pedons have carbonate at the surface. Thickness of the mollic epipedon typically is 7 to 10 inches and ranges from 7 to 14 inches.
The A horizon has hue of 10YR, value of 3 to 5 and 2 or 3 moist, and chroma of 1 or 2. The fine-earth fraction of the A horizon is loam, sandy loam, loamy sand or loamy coarse sand. Where the texture is loamy sand or loamy coarse sand, the mollic epipedon exceeds 10 inches in thickness. The horizon has up to 35 percent rock fragments that are gravel or cobble size. It ranges from neutral to moderately alkaline. The surface of some pedons is covered by stones and boulders. Some pedons have an AC horizon (where the ABk or BCk horizons are absent.
The ABk horizon has hue of 10YR, value of 4 to 6 and 3 or 4 moist, and chroma of 2 or 3. The fine-earth fraction is sandy loam, loamy sand or loam. The horizon has up to 60 percent rock fragments. It is neutral to moderately alkaline.
The BCk horizon is most often identified by carbonates coating the undersides of pebbles and occur in the upper part of the sandy-skeletal material. Some pedons have Bk horizons
The C horizon has 10YR or 2.5Y hue, value of 5 to 7 and 4 to 6 moist, and chroma of 2 to 4. The fine-earth fraction is sand, loamy sand or coarse sand. Individual layers in the C horizon have 15 to 90 percent rock fragments, but the horizon averages more than 35 percent gravel. It is slightly alkaline or moderately alkaline.
COMPETING SERIES: These are the Alpena and Coe series. Alpena soils have limestone cobblestones and gravel. Coe soils have gravel-sized shale fragments and sand-sized shale particles.
GEOGRAPHIC SETTING: Sioux soils are nearly level to undulating on outwash plains and terraces and are undulating to steep on terrace escarpments, eskers, knolls, ridgetops and moraines. Slopes are plane or convex, and gradients range from about 0 to 40 percent. The soil formed in sand and gravel outwash. Mean annual air temperature ranges from about 36 to 47 degrees F, and mean annual precipitation from 16 to 24 inches. Growing season is about 100 to 140 days; average growing season precipitation ranges from 14 to 18 inches; growing degree days are about 2500 to 3000.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arvilla, Barnes, Buse, Divide, Fordville, Forman and Renshaw soils. Arvilla soils are in the sandy family, have a cambic horizon, and are typically on less steep landscapes adjacent to the Sioux soils. Barnes, Buse and Forman soils are fine-loamy and formed in loamy till. Barnes and Forman soils typically are on plane slopes below Sioux soils. Buse soils typically have plane to convex slopes and are above or intermixed with Sioux soils. Divide soils have a calcic horizon within 16 inches and are in plane to concave landscapes adjacent to swales and depressions. Fordville soils are on footslopes below Sioux soils. They have a mollic epipedon more than 16 inches thick and have sand and gravel at depths of 20 and 40 inches. Renshaw soils are on backslopes adjacent to Sioux soils. They have sand and gravel at depths of 14 and 20 inches.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Excessively drained. Surface runoff is very low to medium depending on slope and texture. Saturated hydraulic conductivity is high or very high.
USE AND VEGETATION: Mainly in native range. The dominant vegetation is blue grama, needleandthread, sideoats grama, and sedges.
DISTRIBUTION AND EXTENT: Northeastern South Dakota, eastern North Dakota, and western Minnesota. The Sioux series is of large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Brookings County, South Dakota, 1903.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 9 inches (A and ABk horizons).
ADDITIONAL DATA: Laboratory sample number: S00SD029-005.