LOCATION LAKOA                   SD+ND WY

Established Series
Rev. JWW
05/2011

LAKOA SERIES

The Lakoa series consists of deep and very deep, well drained soils formed in residuum weathered from interbedded sandstone and shale on uplands. Slopes range from 2 to 60 percent. Mean annual precipitation is about 510 millimeters, and mean annual air temperature is about 7 degrees C.

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

TYPICAL PEDON: Lakoa loam - on a northeast-facing slope of 32 percent under ponderosa pine forest at an elevation of about 1,085 meters. When described, the soil was dry throughout. (Colors are for dry soil unless otherwise stated.)

0i--0 to 2 cm; forest litter and partially decomposed forest litter; abrupt smooth boundary. (1 to 4 cm thick)

A--2 to 7 cm; dark gray (10YR 4/1) loam, very dark gray (10YR 3/1) moist; weak fine and medium granular structure; slightly hard, friable, nonsticky and nonplastic; few worm casts; slightly acid; clear wavy boundary. (0 to 13 cm thick)

E--7 to 27 cm; light brownish gray (10YR 6/2) very fine sandy loam, dark grayish brown (10YR 4/2) moist; moderate thin platy structure parting to weak fine granular; slightly hard, very friable, nonsticky and nonplastic; slightly acid; clear wavy boundary. (8 to 20 cm thick)

Bt/E--27 to 35 cm; pale brown (10YR 6/3) loam, brown (10YR 4/3) moist (Bt); many patches and coats of light brownish gray (10YR 6/2) very fine sand, brown (10YR 4/3) moist (E); weak medium prismatic structure parting to weak medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; neutral; gradual wavy boundary. (0 to 15 cm thick)

Bt1--35 to 63 centimeters; light yellowish brown (10YR 6/4) clay loam, dark yellowish brown (10YR 4/4) moist; weak medium prismatic structure parting to moderate medium subangular blocky; hard, firm, moderately sticky and plastic; organoargillans on faces of peds; neutral; gradual wavy boundary.

Bt2--63 to 86 cm; light yellowish brown (10YR 6/4) clay loam, yellowish brown (10YR 5/4) moist; moderate coarse prismatic structure parting to moderate medium subangular blocky; hard, firm, moderately sticky and moderately plastic; organoargillans on faces of peds; few sandstone fragments; neutral; gradual wavy boundary. (Combined thickness of the Bt horizon is 35 to 64 cm.)

Bk--86 to 152 cm; very pale brown (10YR 7/3) loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, friable, nonsticky and slightly plastic; few sandstone fragments, common fine accumulations of lime; strong effervescence; slightly alkaline.

TYPE LOCATION: Meade County, South Dakota; about 1 mile east of Sturgis; 1750 feet north and 850 feet east of the southwest corner of Sec. 11, T. 5 N., R. 5 E.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 6 to 8 degrees C
Mean summer soil temperature: 11 to 15 degrees C
Depth to secondary calcium carbonate: Greater than 50 cm

Particle-size control section (weighted average):
Clay content: 28 to 35 percent
Sand content: 15 to 35 percent fine and coarser sand
Rock fragments: 0 to 20 percent subangular or subrounded sandstone fragments

A horizon:
Hue: 10YR
Value: 4 or 5, 2 or 3 moist
Chroma: 1 to 3
Texture: L, SIL, FSL, VFSL
Clay content: 15 to 27 percent
Reaction: neutral to strongly acid

E horizon:
Hue: 7.5YR or 10YR
Value: 6 or 7, 4 or 5 moist
Chroma: 2 or 3
Texture: L, SIL, VFSL
Clay content: 15 to 27 percent
Reaction: slightly acid to strongly acid

The Bt/E horizon has the combined properties of the Bt and E horizons.

Bt horizon:
Hue: 7.5YR, 10YR, or 2.5Y
Value: 5 to 7, 4 to 6 moist
Chroma: 2 to 6
Texture: CL, SCL, CL
Clay content: 28 to 35 percent
Rock fragments: 0 to 20 percent sandstone gravel
Reaction: moderately acid to neutral

Bk horizon:
Hue: 7.5YR, 10YR, or 2.5Y
Value: 5 to 7, 4 to 6 moist
Chroma: 2 to 4
Texture: L, CL, SCL, FSL, or SL (fine-earth fraction)
Clay content: 16 to 30 percent
Rock fragments: 0 to 35 percent angular and subangular sandstone fragments; 0 to 35 percent gravel, 0 to 15 percent cobble, and 0 to 5 percent stones
Calcium carbonate equivalent: less than 15 percent
Reaction: moderately acid to moderately alkaline

Some pedons have a C horizon

COMPETING SERIES: Alderon, Allens Park, Bayerton, Belltower, Elbeth, Elbuck, Elmark, Haugan, Heflin, Hoyt, Jemco, Jemez, Kunz, Kwiavu, Littlepine, Losindios, Lumpgulch, Northrim, Plome, Shoemaker, Sweetweed, and Tunitcha

Alderon - formed in slope alluvium or colluvium over residuum derived from granite
Allens Park, Bayerton, Belltower, Elmark, Jemco, Jemez Lumpgulch, and Shoemaker - have a lithic contact at 50 to 100 centimeters
Elbeth - formed in slope alluvium from schist, granite, and arkosic bedrock
Elbuck, Heflin, Kunz, Kwiavu, Losindios, Northrim, and Tunitcha - lack E and Bt/E horizons
Haugan - has 20 to 35 percent rock fragments in the Bt
Hoyt - formed in colluvium from igneous rocks and glacial till
Littlepine - contains greater than 40 percent sand in the particle-size control section; additionally the base of the Bt horizon is greater than 100 centimeters
Plome - Bt and lower horizons have hue of 5YR or redder
Sweetweed - formed in colluvium from volcanic mudflow breccia

GEOGRAPHIC SETTING:
Parent material: Colluvium over residuum or residuum from fine-grained sandstone, or interbedded sandstone and shale
Landform: Ridges, ridge shoulders, and dipslopes
Landscape/aspect: mainly on north- and east-facing slopes or protected cove-like positions
Slopes: 2 to 60 percent
Elevation: 975 to 1,460 meters
Mean annual air temperature: 5 to 8 degrees C
Mean annual precipitation: 432 to 584 millimeters
Precipitation pattern: In most years, more than half of the annual precipitation occurs as snow and rain from April through July.
Frost-free period: 100 to 140 days.

GEOGRAPHICALLY ASSOCIATED SOILS:
Butche - lithic contact at less than 50 centimeters; they occur on adjacent backslopes and dipslopes
Boneek - has a mollic epipedon; they occur on less-sloping landscapes below the Lakoa soils
Maitland - has thicker A horizons; they occur in concave positions associated with Lakoa soils

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; saturated hydraulic conductivity is moderately high; medium to very high runoff, depending on slope.

USE AND VEGETATION: Lakoa soils are used for livestock grazing, wildlife habitat, recreation, and homesite and urban development. Native vegetation is ponderosa pine, bur oak, with an understory of shrubs, sedges, little bluestem, and green needlegrass.

DISTRIBUTION AND EXTENT: Lakoa soils occur on the Hogback physiographic area in the Black Hills Footslopes in western South Dakota and northeastern Wyoming, and in western North Dakota; LRR G, MLRA 61; the series is of moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado

SERIES ESTABLISHED: Butte County, South Dakota, 1970.

REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 2 to 27 cm (A and E horizons)
Albic horizon: The zone from 7 to 27 cm (E horizon)
Argillic horizon: The zone from 27 to 86 cm (Bt/E, Bt1, Bt2 horizons)

Classification of the series is changed to fit the typical climatic regime at the series type location.

Taxonomic Version: Keys to Soil Taxonomy, Eleventh Ed., 2010

ADDITIONAL DATA: South Dakota State University (SDSU pedon id number S04SD093-004, samples 91-98). Pedon is in same quarter-section as the series type location. MLRA 61 soil moisture and soil temperature monitoring station (Lakoa series) established in same quarter-section as series type location, June 2005.

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National Cooperative Soil Survey
U.S.A.