LOCATION CONATA SDEstablished Series
TAXONOMIC CLASS: Clayey, smectitic, mesic, shallow Aridic Haplustepts
TYPICAL PEDON: Conata clay - on an upland slope of 6 percent in native grassland area. When described the soil was dry throughout. (Colors are for dry soil unless otherwise stated)
A1--0 to 1 inch; brown (7.5YR 5/2) clay, dark brown (7.5YR 4/2) moist; moderate fine subangular blocky and moderate fine granular structure; very hard, firm, slightly sticky and slightly plastic; 1/4 to 1/2 inch fragile mulch on the surfaces; slightly alkaline; abrupt smooth boundary.
A2--1 to 6 inches; reddish gray (5YR 5/2) clay, dark reddish gray (5YR 4/2) moist; weak fine prismatic structure parting to weak fine subangular blocky; very hard, firm, sticky and plastic; slightly alkaline; clear smooth boundary. (Combined A horizons 3 to 7 inches thick)
Bw--6 to 12 inches; pinkish gray (5YR 6/2) clay, reddish brown (5YR 5/3) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; very hard, firm, sticky and plastic; many very fine fragments of shale; few fine accumulations of carbonates; strong effervescence; moderately alkaline; gradual wavy boundary. (5 to 7 inches thick)
Bk--12 to 17 inches; vari-colored pinkish gray (5YR 6/2), light reddish brown (5YR 6/3), and very pale brown (10YR 7/4) clay, reddish gray (5YR 5/2), reddish brown (5YR 5/3), and yellowish brown (10YR 5/6) moist; weak medium and coarse prismatic structure parting to weak medium and coarse subangular blocky; very hard, very firm, sticky and plastic; many very fine fragments of shale; common fine accumulations of carbonates; strong effervescence; moderately alkaline; gradual wavy boundary. (4 to 8 inches thick)
Cr--17 to 30 inches; vari-colored yellow (10YR 7/6), light gray (10YR 7/1), white (10YR 8/1), and light reddish brown (5YR 6/3) mudstone, brownish yellow (10YR 6/6), gray (10YR 6/1) and reddish brown (5YR 5/3) moist; strong effervescence; moderately alkaline.
TYPE LOCATION: Mellette County, South Dakota; about 9 miles north and 2 miles west of Cedar Butte; 1580 feet east and 2200 feet south of the northwest corner of sec. 18, T. 43 N., R. 31 W.
RANGE IN CHARACTERISTICS: The depth to bedrock ranges from 10 to 20 inches. The soil contains free carbonates throughout except the upper 2 to 4 inches is leached in some pedons. The soil materials reflect the color of the bedrock.
The A horizon has hue of 10R to 5Y, value of 3 to 5 and 2 to 4 moist, and chroma of 2 to 4. It is silty clay or clay. It is neutral or slightly alkaline.
The Bw horizon has hue of 10R to 5Y, value of 3 to 6 dry or moist, and chroma of 2 to 6. It is silty clay or clay and averages between 45 and 55 percent clay. The Bw horizon contains common or many, fine or very fine fragments of mudstone or shale. It is slightly or moderately alkaline.
The Bk horizon has hue of 10R to 5Y, value of 4 to 8 and 4 to 7 moist, and chroma of 2 to 6. It is silty clay or clay and has common to many very fine fragments of shale. It has few to many accumulations of carbonates and is slightly or moderately alkaline.
The Cr horizon is variegated mudstone or shale and has hue of 10R to 5Y. It is slightly or moderately alkaline.
COMPETING SERIES: There are no other series in the same family.
GEOGRAPHIC SETTING: Conata soils are on nearly level to steep areas along drainageways, breaks, and badlands. Surfaces are plane or convex, and slope gradients range from 2 to 40 percent. Conata soils formed in vividly colored clays weathered from mudstone or shale bedrock. The mean annual temperature ranges from 45 to 50 degrees F, and the mean annual precipitation ranges from 12 to 18 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Imlay and Orella soils and the Epping, Imlay, Keota, Larvie, Metre, Norrest and Orella soils. Epping, Imlay, Keota and Orella soils are on positions similar to the Conata soils. Epping soils are loamy and Keota soils have a coarse-silty control section and are deeper to bedrock. Imlay soils have a loamy-skeletal control section. Orella soils are strongly alkaline and have an exchangeable sodium percentage of 8 to 30 percent. Larvie, Metre and Norrest soils typically are on more gentle slopes. Larvie and Metre soils have bedrock between depths of 20 and 40 inches, and in addition, Metre soils have a mollic epipedon. Norrest soils have an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained. Surface runoff is high or very high depending on slope. Permeability is very slow.
USE AND VEGETATION: Rangeland. Native vegetation includes little bluestem, sideoats grama, blue grama, western wheatgrass, needleandthread, sedges and forbs.
DISTRIBUTION AND EXTENT: Of moderate extent in southwestern South Dakota, and possibly portions of Wyoming, Colorado, and Nebraska.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Mellette County, South Dakota, 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon: Ochric epipedon - the zone from the surface of the soil to a depth of 6 inches (A1 and A2 horizons); cambic horizon - the zone from 6 to 12 inches (Bw horizon).