LOCATION DORNA SDEstablished Series
TAXONOMIC CLASS: Coarse-silty over clayey, mixed over smectitic, superactive, mesic Fluventic Haplustolls
TYPICAL PEDON: Dorna silt loam - on a south-facing slope of 1 percent 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) silt loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, very friable; slightly alkaline; abrupt smooth boundary.
A--7 to 15 inches; very dark grayish brown (10YR 3/2) silt loam, very dark brown (10YR 2/2) moist; weak coarse prismatic structure; slightly hard, very friable; few very fine striations of carbonate; slight effervescence; slightly alkaline; clear smooth boundary. (Combined A horizon is 8 to 18 inches thick.)
C--15 to 24 inches; grayish brown (10YR 5/2) silt loam, dark grayish brown (10YR 4/2) moist; weak coarse prismatic structure; slightly hard, very friable; few very fine accumulations of carbonates; strong effervescence; slightly alkaline; abrupt smooth boundary.
2Ck--24 to 27 inches; light brownish gray (10YR 6/2) silty clay, grayish brown (10YR 5/2) moist; moderate medium and fine subangular blocky structure; hard, firm, slightly sticky and slightly plastic; many medium accumulations of carbonate; strong effervescence; moderately alkaline; clear wavy boundary.
2C--27 to 39 inches; grayish brown (2.5Y 5/2) silty clay, dark grayish brown (2.5Y 4/2) moist; weak medium and coarse subangular blocky structure; very hard, firm, sticky and plastic; few fine accumulations of carbonate; strong effervescence; moderately alkaline; clear wavy boundary.
2Ckz--39 to 46 inches; grayish brown (2.5Y 5/2) silty clay, dark grayish brown (2.5Y 4/2) moist; massive; very hard, firm, sticky and plastic; common very fine accumulations of carbonate and salts; slight effervescence; moderately alkaline; gradual wavy boundary.
2C'--46 to 60 inches; grayish brown (2.5Y 5/2) silty clay, dark grayish brown (2.5Y 4/2) moist; massive; very hard, firm, sticky and plastic; few fine and very fine accumulations of salts; slight effervescence; moderately alkaline.
TYPE LOCATION: Hughes County, South Dakota; about 8 1/2 miles south and 3 miles east of Canning; 1/4 mile east and 1/2 mile south along trail road, and 144 feet east of north-south fence from the northwest corner of sec. 3, T. 109 N., R. 76 W.
RANGE IN CHARACTERISTICS: The upper part of the series control section is silt loam or very fine sandy loam averaging less than 18 percent clay and less than 15 percent fine or coarser sand. Depth to the clayey 2C materials typically is about 24 to 30 inches, but ranges from 20 to 40 inches. Some pedons have buried A horizons. These soils typically have free carbonates at depths of 4 to 10 inches, but in some pedons free carbonates are at the surface.
The A horizon has 10YR hue, value of 3 to 5 and 2 or 3 moist, and chroma of 2. It typically is silt loam, but is very fine sandy loam in some pedons. It is neutral or slightly alkaline. Some pedons have a value of 4 moist in the lower part of the A horizon.
The C horizon has 10YR hue, value of 5 or 6 and 4 or 5 moist, and chroma of 2 or 3. It is silt loam or very fine sandy loam and is slightly alkaline or moderately alkaline.
The 2C horizon has hue of 10YR, 2.5Y, or 5Y; value of 5 or 6 and 4 or 5 moist; and chroma of 2 or 3. It has few to many, very fine to coarse accumulations of carbonate. The 2C horizon is silty clay, clay, or silty clay loam with a clay content of 35 to 50 percent clay. It is slightly alkaline or moderately alkaline. It typically has few to common, very fine or fine accumulations of salts in the lower part.
COMPETING SERIES: There are no series in the same family. Other similar series are the Kenesaw, Lowry, Oglala, Sully, and Tripp series. Kenesaw and Lowry soils do not have clayey 2C horizons within depths of 40 inches. Oglala and Tripp soils are drier. Sully soils do not have a mollic epipedon.
GEOGRAPHIC SETTING: The Dorna soils are on nearly level to gently sloping terraces. Slope gradients range from 0 to 4 percent. The soils formed in 20 to 40 inches of silty material deposited over clayey alluvial sediments. Mean annual temperature ranges from 45 to 51 degrees F, and mean annual precipitation ranges from 15 to 24 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Lowry and Sully soils and the Agar soils. All of these soils are on the slightly higher parts of the landscape. Agar soils are fine-silty.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is low. Permeability is moderate in the silty material and slow in the underlying clay.
USE AND VEGETATION: Most areas are used for corn, alfalfa, and small grain. A few areas are irrigated. Native vegetation is dominantly green needlegrass, western wheatgrass, and blue grama.
DISTRIBUTION AND EXTENT: Central and south-central South Dakota adjacent to the Missouri River. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Hughes 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 and A horizons).