LOCATION BULLFLAT SD

Established Series
Rev. JWW
03/2016

BULLFLAT SERIES

The Bullflat series consists of deep and very deep, well drained soils formed in loamy alluvium or colluvium from sedimentary sources. Bullflat soils are on backslope and footslope positions on fans, terraces, benches, lower hillslopes, and in valleys in mountains. Saturated hydraulic conductivity is moderately high. Slopes range from 0 to 15 percent. Mean annual precipitation is about 508 cm (20 inches), and mean annual temperature is about 6.5 degrees C (44 degrees F).

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Typic Argiustolls

TYPICAL PEDON: Bullflat silt loam, on a southeast-facing slope of 1 percent, in alfalfa. When described, the soil was moist to 81 cm (32 inches) and dry below. (Colors are for dry soil unless otherwise noted).

Ap--0 to 15 cm (0 to 6 inches); dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; moderate fine granular structure; soft, very friable, nonsticky and nonplastic; 5 percent fragments of rock; neutral; clear smooth boundary. (10 to 25 cm thick)

Bt1--15 to 25 cm (6 to 10 inches); brown (10YR 5/3) clay loam, dark brown (10YR 3/3) moist; weak medium and fine subangular blocky structure parting to moderate medium granular; hard, friable, moderately sticky and moderately plastic; 5 percent fragments of rock; neutral; clear smooth boundary.

Bt2--25 to 46 cm (10 to 18 inches); brown (7.5YR 5/4) clay loam, brown (7.5YR 4/4) moist; weak medium prismatic structure parting to moderate medium and fine subangular blocky; very hard, friable, moderately sticky and moderately plastic; 5 percent fragments of rock; neutral; clear smooth boundary.

Bt3--46 to 53 cm (18 to 21 inches); yellowish brown (10YR 5/4) clay loam, dark yellowish brown (10YR 4/4) moist; weak medium and coarse prismatic structure parting to weak medium subangular blocky; very hard, friable, slightly sticky and slightly plastic; 5 percent fragments of rock; neutral; abrupt wavy boundary. (Combined thickness of the Bt horizon is 15 to 56 cm.)

Bk--53 to 71 cm (21 to 28 inches); light yellowish brown (10YR 6/4) clay loam, yellowish brown (10YR 5/4) moist; weak coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; 10 percent fragments of rock; many coarse to fine accumulations of carbonate; strong effervescence; moderately alkaline; clear smooth boundary. (0 to 50 cm thick)

Ck--71 to 81 cm (28 to 32 inches); very pale brown (10YR 7/4) gravelly clay loam, light yellowish brown (10YR 6/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; 30 percent fragments of rock; few fine accumulation of carbonate; strong effervescence; moderately alkaline; clear smooth boundary.

C--81 to 200 cm (32 to 80 inches); very pale brown (10YR 8/4) very cobbly clay loam, very pale brown (10YR 7/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; carbonates coat undersides of pebbles; 40 percent fragments of rock; strong effervescence; moderately alkaline.

TYPE LOCATION: Pennington County, South Dakota; about 14.75 km (9 miles) south and 3.3 km (2 miles) west of Rapid City; 244 m (800 feet) east and 762 m (2,500 feet) north of the southwest corner of sec. 21, T. 1 S., R. 7 E.; Rockerville quadrangle; 43 degrees, 56 minutes, 51.93 seconds north latitude, and 103 degrees, 17 minutes, 45.42 seconds west longitude; NAD 83.

RANGE IN CHARACTERISTICS:
Depth to bedrock: typically greater than 150 cm (60 inches), may range from 100 to 150 cm (40 to 60 inches)
Depth to carbonates: 25 to 86 cm (10 to 34 inches)
Clay content (control section average): typically 25 to 35 percent, will range as low as 20
Sand content (0 to 150 cm): 20 to 40 percent, with 15 to 25 percent being fine and coarser sand

A horizon:
Hue: 5YR, 7.5YR, or 10YR
Value: 3 or 4 dry, 2 or 3 moist
Chroma: 1 or 2
Texture: silt loam, loam
Rock fragments: 0 to 15 percent strongly cemented to indurated, subangular to subrounded limestone and/or sandstone gravel
Reaction: medium acid to neutral

Bt horizon:
Hue: 5YR, 7.5YR, or 10YR
Value: 4 to 6 dry, 3 or 4 moist
Chroma: 3 or 4
Texture: clay loam, silty clay loam, or silt loam
Rock fragments: 0 to 15 percent strongly cemented to indurated, subangular to subrounded limestone and/or sandstone gravel
Reaction: slightly acid to slightly alkaline

Bk horizon (and C horizon in some pedons):
Hue: 5YR, 7.5YR, or 10YR
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 3 or 4
Texture: clay loam, silty clay loam, silt loam, including gravelly or cobbly textural modifiers
Rock fragments: 0 to 35 percent strongly cemented to indurated, subangular to subrounded limestone and/or sandstone gravel or cobble
Calcium carbonate content: 5 to 15 percent
Reaction: slightly alkaline or moderately alkaline

C and Ck horizons:
Hue: 2.5YR, 5YR, 7.5YR, or 10YR
Value: 6 to 8 dry, 4 to 7 moist
Chroma: 3 to 6
Texture: gravelly, very gravelly, cobbly, or very cobbly modifiers of clay loam, silty clay loam, loam, or silt loam
Rock fragments: 15 to 50 percent strongly cemented to indurated, subangular to subrounded limestone and/or sandstone gravel or cobble
Calcium carbonate content: 5 to 15 percent
Reaction: slightly alkaline or moderately alkaline

COMPETING SERIES:
Absarook - has a lithic contact between 50 and 100 cm (20 to 40 inches)
Archmesa - has a lithic contact between 50 and 100 cm (20 to 40 inches)
Beartooth - has more than 35 percent rock fragments in the Bk horizon, and occurs on slopes of 25 to 50 percent
Beeno - has a paralithic contact between 50 and 100 cm (20 to 40 inches)
Bielenberg - formed in alluvium, colluvium and residuum derived from granitic and other coarse grained igneous rocks
Bitterroot - has a paralithic contact between 50 and 100 cm (20 to 40 inches)
Bookcliff - has a lithic contact between 100 and 150 cm (40 to 60 inches)
Burtoner - do not have horizons of secondary calcium carbonate accumulation; has a lithic contact between 50 and 100 cm (20 to 40 inches)
Clancy - formed in colluvium or residuum derived from granite bedrock; has decomposed granite bedrock (grus) between 50 and 100 cm (20 to 40 inches)
Clasoil - formed in alluvium or outwash derived from granitic and other coarse grained igneous rocks; does not have horizons of secondary calcium carbonate accumulation
Dooley - has substrata consisting of till or lacustrine deposits
Doughty - has a calcic horizon between 25 and 61 cm (10 to 24 inches)
Empedrado - formed in material weathered mainly from rhyolite, andesite, and trachite
Fairfield - has a calcic horizon between 18 and 25 cm (7 to 10 inches)
Farnuf - formed in glaciolacustrine or glaciofluvial deposits, and does not allow for red hue
Farside - formed in alluvium from gneiss, schist and sandstone; do not have a horizon of secondary calcium carbonate accumulation
Felor - has a lithologic discontinuity, of loamy sediments overlying clayey sediments, between 50 and 100 cm (20 to 40 inches)
Floak - has a lithic contact between 50 and 100 cm (20 to 40 inches)
Greenway - has high bulk density clay loam till between 38 and 51 cm (15 to 25 inches)
Gurney - has a lithic contact between 50 and 100 cm (20 to 40 inches)
Hangdo - does not have horizons of secondary calcium carbonate accumulation
Hoppers - has a lithic contact between 50 and 100 cm (20 to 40 inches)
Howbert - has secondary calcium carbonate accumulations throughout the argillic horizon; has a calcic horizon between 41 and 63 cm (16 to 25 inches)
Hyalite - does not have horizons of secondary calcium carbonate accumulation
Jeffcity - has a lithic contact between 50 and 100 cm (20 to 40 inches)
Kokoruda - does not have horizons of secondary calcium carbonate accumulation
Livona - has till between 25 and 51 cm (10 to 20 inches)
Martinsdale - has a calcic horizon between 28 and 76 cm (11 to 30 inches)
Maudlin - has a lithic contact between 50 and 100 cm (20 to 40 inches)
Meagher - has a calcic horizon between 28 and 50 cm (11 to 20 inches)
Moen - has a lithic contact between 50 and 100 cm (20 to 40 inches)
Moento - has a lithic contact between 50 and 100 cm (20 to 40 inches)
Perrypark - have hue redder than 7.5YR; does not have horizons of secondary calcium carbonate accumulation
Pianohill - has a lithic contact between 50 and 100 cm (20 to 40 inches)
Placerton - has a paralithic contact of decomposed granite bedrock (grus) between 50 and 100 cm (20 to 40 inches)
Reeder - has a paralithic contact between 50 and 100 cm (20 to 40 inches)
Reedwest - has a paralithic contact between 50 and 100 cm (20 to 40 inches)
Sipple - base of the argillic horizon is less than 38 cm
Snakejohn - has a calcic horizon between 38 and 76 cm (15 to 30 inches)
Sponseller - formed in colluvium and alluvium from basalt and pyroclastic rocks; does not have horizons of secondary calcium carbonate accumulation
Trag - formed in material weathered from granite and schist; does not have horizons of secondary calcium carbonate accumulation
Tragmon - does not have horizons of secondary calcium carbonate accumulation
Trazuni - has more than 35 percent sand in the particle-size control section; does not have horizons of secondary calcium carbonate accumulation
Trujillo - does not have horizons of secondary calcium carbonate accumulation above 100 cm (40 inches)
Ulrant - has 20 to 35 percent granitic gravel in the argillic (Bt) horizon
Vida - base of the argillic horizon is less than 25 cm (10 inches); formed in till
Watne - has a calcic horizon between 41 and 71 cm (16 to 28 inches)
Watrous - has a lithic contact between 50 and 100 cm (20 to 40 inches)
Wemple - has a calcic horizon between 33 and 81 cm (13 to 32 inches)
Williams - formed in calcareous till
Yegen - contain more sand in the subsoil and substratum

GEOGRAPHIC SETTING:
Parent material: alluvium or colluvium from limestone, or interbedded limestone and sandstone
Landform: terraces, fans, hillslopes, valleys
Landscape: mountains
Slopes: 0 to 15 percent
Elevation: 1,158 to 1,890 meters (3,800 to 6,200 feet)
Mean annual air temperature: 4.5 to 7.5 degrees C (40 to 46 degrees F)
Mean annual precipitation: 432 to 559 mm (17 to 22 inches)
Precipitation pattern: over one-half the mean annual precipitation falls as snow and rain during the period March through July
Frost-free season: 80 to 120 days

GEOGRAPHICALLY ASSOCIATED SOILS:
These are the competing Gurney series and the Cordeston, Hilger, and Rockerville series.
Cordeston - have a mollic epipedon more than 41 cm (16 inches) thick and do not have argillic horizons; on the lower landscape positions
Gurney - on higher landscape positions
Hilger - are loamy-skeletal; on similar landscape positions, typically above Bullflat
Rockerville - are shallow to bedrock; on higher, convex landscape positions

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage - Well drained
Saturated hydraulic conductivity - moderately high
Runoff - low to medium, depending on slope

USE AND VEGETATION: Used for livestock grazing, hayland and pasture, wildlife habitat, and recreation. Native vegetation is western wheatgrass, junegrass, green needlegrass, blue grama, needleandthread, and sedges. When utilized as hayland and pasture, cultivars of alfalfa, smooth brome, and intermediate wheatgrass are common.

DISTRIBUTION AND EXTENT: Black Hills of western South Dakota and northeastern Wyoming, especially on the low limestone plateau physiographic area; LRR G, MLRA 62. The series is of small extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Salina, Kansas

SERIES ESTABLISHED: soil Survey of Custer and Pennington Counties, Black Hills Parts, South Dakota, 1985.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 25 cm (0 to 10 inches); (Ap, Bt1 horizons)
Argillic horizon - 15 to 53 cm (6 to 21 inches); (Bt1, Bt2, Bt3 horizons)
Secondary accumulations of calcium carbonate - 53 to 81 cm (21 to 32 inches); (Bk, Ck horizons)

The taxonomic class/soil moisture regime is changed from udic to ustic with this update. The type location for the series, and the majority of the mapped extent, is in the ustic moisture zone in MLRA 62.

Taxonomic Version: Keys to Soil Taxonomy, Twelvth Edition, 2014

National Cooperative Soil Survey
U.S.A.