LOCATION ETHAN SDEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Typic Calciustolls
TYPICAL PEDON: Ethan loam - on a 5 percent convex southeast-facing slope in a cultivated field. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 8 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; slightly hard, friable; strong effervescence (11 percent calcium carbonate); slightly alkaline; abrupt smooth boundary. (4 to 10 inches thick)
Bk1--8 to 21 inches; light brownish gray (2.5Y 6/2) clay loam, grayish brown (2.5Y 5/2) moist; weak medium prismatic structure parting to weak medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; common fine masses of calcium carbonate; violent effervescence (28 percent calcium carbonate); slightly alkaline; gradual wavy boundary.
Bk2--21 to 32 inches; light gray (2.5Y 7/2) clay loam, light brownish gray (2.5Y 6/2) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine masses of calcium carbonate; violent effervescence (22 percent calcium carbonate); moderately alkaline; gradual wavy boundary. (Combined Bk horizons is 10 to 45 inches thick.)
C--32 to 60 inches; pale yellow (2.5Y 7/4) clay loam, light yellowish brown (2.5Y 6/4) moist; common fine prominent mottles of strong brown (7.5YR 5/6) and gray (5Y 6/1) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few fine masses of calcium carbonate; violent effervescence (18 percent calcium carbonate); slightly alkaline.
TYPE LOCATION: Turner County, South Dakota; 16 miles west and 2 north of Viborg; 1040 feet north and 140 feet west of the southeast corner of sec. 19, T. 97 N., R. 55 W.
RANGE IN CHARACTERISTICS: Calcium carbonates are typically at the surface, but some pedons in native grass are leached to 5 inches. The calcic horizon has a calcium carbonate equivalent ranging from 15 to 35 percent. The mollic epipedon is 7 to 10 inches thick. The particle size control section averages between 18 and 30 percent clay and contains up to 5 percent pebbles by volume. Some pedons contain up to 35 percent by volume of stones.
The A horizon has 10YR or 2.5Y hue, value of 3 to 5 and 2 or 3 moist, and chroma of 2 or 3. It typically is loam or clay loam but is silt loam or gravelly loam in some pedons. In areas mantled by sandy sediments, it is loamy fine sand or sandy loam. It ranges from neutral to moderately alkaline.
The Bk horizon has 10YR or 2.5Y hue, value of 5 to 7 and 3 to 6 moist and chroma of 2 to 4. It is loam or clay loam and is slightly alkaline or moderately alkaline. It typically has few to many masses of calcium carbonate.
The C horizon has 2.5Y or 5Y hue, value of 5 to 8 and 4 to 6 moist, and chroma of 2 to 4. It typically is loam or clay loam, but in some pedons it is stratified loam, clay loam, silt loam, and fine sandy loam. It ranges from slightly alkaline to strongly alkaline and has few to many masses of calcium carbonate. It has mottles inherent to the parent material and masses of gypsum in some pedons.
COMPETING SERIES: These are the Campus and Penden series. Campus soils have a lithic contact between depths of 20 and 40 inches. Penden soils do not have pebbles in the control section. In addition, Campus and Penden soils have warmer soil temperatures.
GEOGRAPHIC SETTING: Ethan soils are on upland till plains. Slopes typically are short and irregular and surfaces are convex. Slope gradient ranges from 1 to 40 percent. These soils typically formed in calcareous loam and clay loam glacial till and some silty glacial materials. Mean annual air temperature ranges from 45 to 52 degrees F., and mean annual precipitation ranges from 17 to 26 inches. Growing season is about 130 to 150 days; average growing season precipitation ranges from 14 to 18 inches; and average growing degree days are about 2800 to 3300.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Betts, Bonilla, Clarno, Davison, Eakin, Egan, Hand, Homme, Houdek, and Prosper soils. Betts soils are on similar landscapes and do not have a mollic epipedon. Bonilla and Prosper soils are in swales and have mollic epipedons more than 20 inches thick. Clarno, Egan, Eakin, Hand, Homme, and Houdek soils are leached of carbonates to depths of more than 5 inches and are on similar but less sloping landscapes. In addition, they typically are below areas of Ethan soils. Davison soils are on slight rises adjacent to depressed drainageways and closed depressions and have redoximorphic features within 30 inches.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium to very high. Permeability is moderate in the solum and moderately slow in the underlying material.
USE AND VEGETATION: These soils are mostly cultivated. Principal crops are small grain, corn, alfalfa, and pasture. Native vegetation is big bluestem, blue grama, green needlegrass, little bluestem, needleandthread, sideoats grama, western wheatgrass, and sedges.
DISTRIBUTION AND EXTENT: Large extent in east central and south central South Dakota, east of the Missouri River.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Hutchinson County, South Dakota, 1974.
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 8 inches (Ap horizon); calcic horizon - the zone from about 8 to 32 inches (Bk1, Bk2 horizons).