LOCATION WENTWORTH SD+IAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Udic Haplustolls
TYPICAL PEDON: Wentworth silty clay loam - on a 3 percent, southwest-facing convex slope in a cultivated field. When described the soil was dry throughout. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 7 inches; dark grayish brown (10YR 4/2) silty clay loam, very dark brown (10YR 2/2) moist; weak fine granular structure; slightly hard, friable, slightly sticky; slightly acid; abrupt smooth boundary. (5 to 10 inches thick)
Bw1--7 to 15 inches; brown (10YR 5/3) silty clay loam, very dark grayish brown (10YR 3/2) crushing to dark brown (10YR 3/3) moist; weak coarse and medium prismatic structure parting to weak coarse and medium subangular blocky; slightly hard, friable, slightly sticky; slightly acid; gradual wavy boundary.
Bw2--15 to 26 inches; brown (10YR 5/3) silty clay loam, dark brown (10YR 4/3) moist; few fine distinct dark brown (7.5YR 4/4) mottles; moderate coarse and medium prismatic structure parting to weak coarse and medium subangular blocky; slightly hard, friable, slightly sticky; few fine dark concretions (iron and manganese oxides); neutral; clear wavy boundary. (Combined Bw horizons is 10 to 26 inches thick.)
Bk1--26 to 34 inches; light brownish gray (2.5Y 6/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; many fine and medium distinct olive gray (5Y 5/2) and dark yellowish brown (10YR 4/4) mottles; few fine and medium olive brown (2.5Y 4/4) mottles; weak coarse prismatic structure parting to weak medium subangular blocky; hard, friable, slightly sticky; common fine and medium accumulations (iron and manganese oxides); many fine and medium soft accumulations of carbonate; strong effervescence; moderately alkaline; gradual wavy boundary.
Bk2--34 to 48 inches; light brownish gray (2.5Y 6/2) silty clay loam, grayish brown (2.5Y 5/2) moist; common fine and medium distinct dark yellowish brown (10YR 4/4) and yellowish brown (10YR 5/6) mottles and few fine and medium distinct dark brown (7.5YR 4/4) mottles; weak coarse and medium subangular blocky structure; hard, friable, slightly sticky; common fine and medium dark accumulations (iron and manganese oxides); common fine and medium accumulations of carbonate; strong effervescence; moderately alkaline; gradual wavy boundary. (Combined Bk horizons is 10 to 30 inches thick.)
C--48 to 60 inches; light brownish gray (2.5Y 6/2) silty clay loam, grayish brown (2.5Y 5/2) moist; common fine and medium distinct dark yellowish brown (10YR 4/4) and yellowish brown (10YR 5/6) mottles, and few fine and medium distinct dark brown (7.5YR 4/4) mottles; weak coarse and medium subangular blocky structure; hard, friable, slightly sticky; common fine and medium dark accumulations (iron and manganese oxides); few fine and medium soft accumulations of carbonate; strong effervescence; moderately alkaline.
TYPE LOCATION: Lake County, South Dakota; about 3 miles south and 1 1/2 miles west of Nunda; 2,475 feet east and 300 feet north of the southwest corner, sec. 35, T. 108 N., R. 52 W.
RANGE IN CHARACTERISTICS: The depth to free calcium carbonate typically is 26 inches and ranges from 20 to 36 inches. Thickness of the mollic epipedon ranges from 8 to 20 inches and extends into the Bw horizon of most pedons.
The A horizon has hue of 10YR, value of 3 or 4 and 2 or 3 moist, and chroma of 1 or 2. It is silty clay loam or silt loam and ranges from moderately acid to neutral.
The Bw horizon has hue of 10YR or 2.5Y, value of 4 to 6 and 2 to 4 moist, and chroma of 2 to 4, and is silty clay loam or silt loam averaging between 25 and 35 percent clay. It is slightly acid or neutral.
The Bk horizon has hue of 10YR or 2.5Y, value of 4 to 7 and 4 to 6 moist, and chroma of 2 to 4. It is silty clay loam or silt loam. It has common to many accumulations of calcium carbonate. It is slightly alkaline or moderately alkaline. Some pedons have 2Bk horizons of clay loam glacial till below depths of 40 inches.
The C horizon has hue of 10YR or 2.5Y, value of 5 to 7 and 4 to 6 moist, and chroma of 2 to 4, and is silt loam or silty clay loam. Thin strata of loam or sandy loam are in some pedons. The stratified materials typically extend to depths of 5 feet or more. It is slightly alkaline or moderately alkaline. Some pedons have 2C horizons of clay loam glacial till at depths of 40 to 60 inches. Stones and pebbles are common in some pedons. There is considerable variation in mottling and iron staining.
COMPETING SERIES: These are the Egan, Ihlen, Moody, and Nora series. Egan soils have glacial till at depths of 24 and 40 inches. Ihlen soils have bedrock at depths of 20 and 40 inches. Moody and Nora soils have lower sand content. Moody soils are leached to greater depths.
GEOGRAPHIC SETTING: Wentworth soils are nearly level to rolling on uplands. Surfaces are plane to convex, and slope gradients range from 0 to 9 percent. These soils formed in silty glacial drift. In some areas glacial till is at 40 to 60 inches. Mean annual temperature ranges from 45 to 52 degrees F, and the mean annual precipitation ranges from 20 to 26 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Egan soils and the Beadle, Chancellor, Clarno, Ethan, Huntimer, Shindler, Steinauer, Trent, Viborg, Wakonda, and Whitewood soils. Egan soils are on higher parts of the landscape. Chancellor, Trent, Viborg, and Whitewood soils are in the swales. Chancellor soils are wetter and have a fine-textured argillic horizon. Trent, Viborg, and Whitewood soils have mollic epipedons greater than 20 inches thick. The Beadle, Ethan, Shindler, and Steinauer soils formed in glacial till and are on convex slopes in the more undulating areas. Clarno soils have a fine-loamy control section and are on the convex to plane slopes of the landscape. Huntimer soils have a fine textured control section and are on slightly higher landscapes. Wakonda soils have a calcic horizon and are at edges of swales and depressions.
DRAINAGE AND PERMEABILITY: Well drained and moderately well drained; surface runoff is slow on nearly level slopes and medium on more sloping areas. Permeability is moderate. Permeability of the glacial till is moderately slow. The moderately well drained phase has a perched water table at a depth of 3 to 6 feet from October to July in most years.
USE AND VEGETATION: Most areas are used to grow corn, small grain, soybeans, and alfalfa. The native vegetation is mainly little bluestem, big bluestem, needleandthread, western wheatgrass, blue grama and sideoats grama, and green needlegrass.
DISTRIBUTION AND EXTENT: East-central and southeastern South Dakota and northwest Iowa. Series is of large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Lake County, South Dakota, 1970.
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 15 inches (Ap, Bw1 horizon).