LOCATION PROMISE SD+MT NEEstablished Series
TAXONOMIC CLASS: Very-fine, smectitic, mesic Typic Haplusterts
TYPICAL PEDON: Promise clay - on a slightly concave south-facing slope of 4 percent in native grass. (When described the soil was dry throughout. Colors are for dry soil unless otherwise stated.)
A1--0 to 3 inches; dark gray (10YR 4/l) clay, very dark gray (10YR 3/l) moist; moderate medium and fine subangular blocky structure; hard, firm, sticky and plastic; common fine roots; neutral; clear wavy boundary.
A2--3 to 8 inches; dark gray (10YR 4/l) clay, very dark gray (10YR 3/l) moist; weak medium and fine subangular blocky structure parting to moderate fine granular; hard, firm, sticky and plastic; common fine roots; cracks 1/2 to 1 inch wide; slightly alkaline; gradual wavy boundary. (Combined A horizon 4 to 10 inches thick)
Bss--8 to 16 inches; grayish brown (2.5Y 5/2) clay, very dark grayish brown (2.5Y 3/2) moist; moderate medium and coarse blocky and subangular blocky structure; extremely hard, very firm, very sticky and very plastic; few fine roots; cracks 1/2 to 1 inch wide; few intersecting slickensides; common tongues of very dark gray (10YR 3/l) moist; strong effervescence; moderately alkaline; gradual wavy boundary. (8 to 22 inches thick)
Bkss--16 to 25 inches; light brownish gray (2.5Y 6/2) clay, dark grayish brown (2.5Y 4/2) moist; moderate coarse subangular blocky structure; extremely hard, very firm, very sticky and very plastic; few fine roots; cracks 1/2 to 1 inch wide; few intersecting slickensides; few tongues of very dark gray (10YR 3/l) moist; few fine accumulations of carbonate; strong effervescence; moderately alkaline; gradual wavy boundary. (0 to 16 inches thick)
Css--25 to 36 inches; light brownish gray (2.5Y 6/2) clay, dark grayish brown (2.5Y 4/2) moist; weak coarse subangular blocky structure; extremely hard, very firm, very sticky and very plastic; few fine roots; few intersecting slickensides; strong effervescence; moderately alkaline; gradual wavy boundary.
Cy--36 to 47 inches; light brownish gray (2.5Y 6/2) clay, dark grayish brown (2.5Y 4/2) moist; massive; very hard, firm, sticky and plastic; few fine roots; common fine distinct iron stains of light yellowish brown(10YR 6/4) moist; common fine and medium nests and seams of gypsum crystals; strong effervescence; moderately alkaline; gradual wavy boundary.
C--47 to 60 inches; grayish brown (2.5Y 5/2) and light brownish gray (2.5Y 6/2) clay, dark grayish brown (2.5Y 4/2) and grayish brown (2.5Y 5/2) moist; massive; hard, firm, sticky and plastic; few fine distinct iron stains of light yellowish brown (10YR 6/4) moist; few fine nests of gypsum crystals; strong effervescence; moderately alkaline.
TYPE LOCATION: Stanley County, South Dakota; about l 1/4 mile north and 3 1/2 miles east of Hayes; 960 feet north and 52 feet east of fence from southwest corner of sec.14, T. 5 N., R. 26 E.
RANGE IN CHARACTERISTICS: The soil typically does not have carbonates to depths of 4 to 15 inches, but some pedons contain carbonates at the surface. The depth to weathered shale is typically greater than 5 feet but is as shallow as 40 inches in some pedons. When the soil is dry, cracks 1/2 inch to 2 inches wide and several feet long extend downward through the solum. The soil typically averages about 60 to 65 percent clay. It has a mollic epipedon 7 to 16 inches thick and in some pedons it extends into the lower part of the B horizon.
The A horizon has hue of 10YR or 2.5Y, value of 4 or 5 and 2 or 3 moist, and chroma of l or 2. It typically is clay, but is silty clay in some pedons. It ranges from slightly acid to slightly alkaline. The upper l/2 to l inch typically has granular structure and forms a thin porous crust when dry.
The Bss horizon has hue of 2.5Y or 5Y, value of 4 to 6 and 2 to 4 moist, and chroma of 2 to 4. It is extremely hard or very hard and extremely firm or very firm. It is slightly or moderately alkaline.
The Bk horizon has hue of 2.5Y or 5Y, value of 5 or 6 and 4 to 5 moist, and chroma of 2 to 4. It has few to common accumulations of carbonates and is slightly or moderately alkaline. Some pedons have a BC horizon.
The C horizon has hue of 2.5Y or 5Y, value of 5 or 6 and 4 or 5 moist, and chroma of 2 to 4. The C horizon below depths of 40 inches is clay or silty clay but includes coarser sediments in some pedons. The C horizon has few or common accumulations of gypsum in fine nests and seams. It ranges from slightly alkaline to strongly alkaline.
COMPETING SERIES: This is the Bullcreek series. Bullcreek soils contain salts in the solum.
GEOGRAPHIC SETTING: Promise soils are level to strongly sloping on uplands, colluvial fans, and terraces. Slopes are typically long and plane or slightly concave. Slope gradients range from 0 to 15 percent. Gilgai microrelief is in most areas. The soil formed in clay sediments weathered from clay shales. Mean annual air temperature ranges from about 45 to 50 degrees F, and precipitation from about 15 to 24 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Bullcreek soils and the Chantier, Dupree, Hurley, Labu, Lakoma, Millboro, Opal, Sansarc, Verdel and Witten soils. Bullcreek soils are on toe slopes and flats below the Promise soils. The Chantier, Dupree and Sansarc soils are on the steeper convex nearby slopes and have bedrock within 20 inches of the surface. Hurley soils are in positions similar to the Promise soils and have a natric horizon. Labu, Lakoma and Opal soils are on higher positions. Labu soils do not have a mollic epipedon. Lakoma and Opal soils have bedrock within depths of 20 to 40 inches. Millboro soils are on similar landscapes as the Promise soils. Verdel soils have a fine textured control section and are below the Promise soils. Witten soils are in swales and have a mollic epipedon greater than 20 inches thick and are fine-textured.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is low to very high depending on slope and surface texture. Permeability is slow or very slow, except after dry periods when the initial intake in cracks is rapid.
USE AND VEGETATION: The soils are used for cropland and rangeland. Small grain, sorghum, and alfalfa are the principal crops. Native vegetation is mostly western wheatgrass, green needlegrass, blue grama, sideoats grama, sedges and forbs.
DISTRIBUTION AND EXTENT: Central South Dakota, and north-central Nebraska. The soil is extensive.
MLRA OFFICE RESPONSIBLE: Bismarck, North Dakota
SERIES ESTABLISHED: Potter County, South Dakota, 1955.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 16 inches (A1, A2 and Bss horizons; Vertisol criteria - cracks to a depth of 25 inches (A2, Bss and Bkss horizons) and intersecting slickensides (Bss, Bkss and Css horizons).
ADDITIONAL DATA: NSSL-79P218-223 and 79P224-229.