LOCATION BLACKPIPE SDEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aridic Argiustolls
TYPICAL PEDON: Blackpipe silt loam - on a west-facing 3 percent slope in native range. When described the soil was dry throughout except for upper 4 inches. (Colors are for dry soil unless otherwise stated).
A--0 to 6 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; slightly hard, friable; many fine and medium roots; neutral; clear smooth boundary. (3 to 7 inches thick)
Bt1--6 to 13 inches; grayish brown (2.5Y 5/2) silty clay, very dark grayish brown (2.5Y 3/2) moist; moderate fine and medium prismatic structure parting to moderate fine subangular blocky; hard, firm, sticky and plastic; shiny surfaces on faces of peds; common fine and medium roots; neutral; clear wavy boundary.
Bt2--13 to 17 inches; grayish brown (2.5Y 5/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; moderate medium prismatic structure parting to moderate fine and medium subangular blocky; hard, firm, sticky and plastic; shiny surfaces on faces of peds; common fine and medium roots; slight effervescence; slightly alkaline; gradual wavy boundary. (Combined B2t horizons is 9 to 18 inches thick.)
Bk1--17 to 25 inches; light brownish gray (2.5Y 6/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; weak coarse prismatic structure parting to weak medium subangular blocky; hard, firm, sticky and plastic; few fine roots; few fine accumulations of carbonate; strong effervescence; slightly alkaline; gradual wavy boundary.
Bk2--25 to 34 inches; light brownish gray (2.5Y 6/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; weak coarse prismatic structure parting to weak coarse subangular blocky; slightly hard, friable; common fine roots; few fine accumulations of carbonate; strong effervescence; slightly alkaline; clear wavy boundary. (Combined Bk horizons is 8 to 20 inches thick.)
Cr--34 to 50 inches; light brownish gray (2.5Y 6/2) silty shale, grayish brown (10YR 5/2) moist; few fine roots in upper 10 inches; few nests of gypsum crystals; easily dug when moist; slight effervescence in upper part; slightly alkaline.
TYPE LOCATION: Meade County, South Dakota; about 8 miles east and 11 miles north of Sturgis; 550 feet east and 75 feet south of northwest corner of sec. 14, T. 7 N., R. 31 W.
RANGE IN CHARACTERISTICS: The depth to carbonates ranges from 12 to 25 inches. The thickness of the mollic epipedon ranges from 7 to 18 inches with streaks and tongues extending into the underlying horizon of some pedons. The CEC/clay ratio ranges from .60 to 1.0 in the A and Bt horizon and from .60 to as much as 2.0 below. Soft, but brittle, siltstone or shales are between depths of 20 and 40 inches.
The A horizon has hue of 10YR, value of 3 to 5 and 2 or 3 moist, and chroma of 1 or 2. It typically is a silt loam or silty clay loam, but is clay loam in some pedons. It ranges from slightly acid to slightly alkaline.
The Bt horizon has hue of 10YR or 2.5Y, value of 3 to 5 and 2 to 4 moist, and chroma of 1 or 2. It is silty clay, clay loam, silty clay or clay averaging between 35 to 50 percent clay and contains less than 15 percent fine sand or coarser. It is neutral or slightly alkaline.
The Bk horizon has hue of 10YR or 2.5Y, value of 5 to 7 and 4 or 5 moist, and chroma of 1 or 2. They are silt loam, loam, silty clay loam, or clay loam. Some pedons have few to many very fine particles of siltstone or shale which do not soften when wet. The Bk horizon contains 5 to about 20 percent accumulations of carbonate and it is slightly or moderately alkaline.
Some pedons have a C horizon with color and texture of the Bk horizon.
The Cr horizon is shale, mudstone, or siltstone. It ranges from slightly alkaline to strongly alkaline.
COMPETING SERIES: These are the Ashfork, Boneek, Boquillas, Chapin, Collbran, Emigrant, Huggins, Kube, Leyden, Loma, Nuncho, Nunn, Querc, Rednun, Richfield, Ryus, Savo, Showlow, Sofia, Standley, Thunderbird, Torreon, and Wormser. Ashford and Thunderbird soils have a lithic contact at depths of 20 to 40 inches. Leyden soils contain more coarse fragments. Boneek, Collbran, Kube, Nuncho, Nunn, Rednun, Richfield, Ryus, Savo, Sofia, Showlow, Standley, Torreon, and Wormser do not have bedrock between depths of 20 and 40 inches. In addition, Boneek, Collbran, and Rednun have hue of 7.5YR or redder; Kube soils have higher CEC/clay ratios; Nunn, Rednun, and Wormser soils contain more fine sand or coarser; Ryus soils have carbonates at or near the surface; Sofia soils contain more clay; and Torreon soils formed in sediments influenced by basalt. Chapin soils have hue of 7.5YR or redder. Boquillas soils contain more coarse fragments and have redder hue in the argillic horizon. Leyden soils contain more coarse fragments. Emigrant, Leyden, and Querc soils contain more fine sand or coarser. Huggins soils have higher CEC/clay ratios. Loma soils have hue of 5YR or redder and contain free carbonates throughout.
GEOGRAPHIC SETTING: Blackpipe soils are on nearly level to strongly sloping landscapes. Slope gradients range from 0 to 15 percent. Surfaces are mostly plane or slightly concave. These soils formed in clayey residuum weathered from shale and mudstone. Mean annual temperature ranges from about 45 to 49 degrees F, and precipitation ranges from about 12 to 19 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Norrest and Savo soils and the Cedar Butte, Imlay, Midway, and Okreek soils. Norrest soils are on the adjacent high convex landscapes. Savo soils are on concave surfaces and are typically below the Blackpipe soils in the landscape. Cedar Butte soils have a natric horizon and are in slightly depressed to concave positions below the Blackpipe soils. Midway and Imlay soils are on steeper slopes and do not have a mollic epipedon and have bedrock within depths of 12 to 20 inches. Okreek soils are on broad flats and have more than 60 percent clay in the argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium on 0 to 2 percent slopes and high or very high on 2 to 15 percent slopes. Permeability is moderately slow.
USE AND VEGETATION: Mostly in rangeland; native vegetation consists largely of western wheatgrass, blue grama, green needlegrass, and needleandthread.
DISTRIBUTION AND EXTENT: Southwestern South Dakota. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Mellette County, South Dakota, 1971.
REMARKS: Diagnostic features and horizons recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to the depth of 13 inches (A and Bt1 horizons); argillic horizon - the zone from 6 to 17 inches (Bt1 and Bt2 horizons).