LOCATION THIRTYNINE              WY+NE SD

Established Series
Rev MCS/CJH/JWW
09/2011

THIRTYNINE SERIES

The Thirtynine series consists of very deep, well drained soils on fan remnants, terraces, hill footslopes, and toeslopes. The soils formed in alluvium derived primarily from siltstone and fine grained sandstone. Slopes are 0 to 15 percent. Elevation is 975 to 1,730 meters. The mean annual precipitation is about 350 mm and the mean annual temperature is about 8 degrees.

TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aridic Argiustolls

TYPICAL PEDON: Thirtynine silt loam - on an east facing slope of three percent, utilized as rangeland. (Colors are for dry soil unless otherwise stated)

A1--0 to 8 cm; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate medium granular structure parting to weak very fine granular; soft, very friable, slightly sticky and slightly plastic; common very fine and fine roots; neutral; clear smooth boundary.

A2--8 to 20 cm; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine and fine roots; slightly alkaline; clear smooth boundary. (Combined thickness of the A horizon is 12 to 24 cm)

Bt--20 to 38 cm; grayish brown (10YR 5/2) silty clay loam, dark grayish brown (10YR 4/2) moist; moderate medium prismatic structure; hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; many faint, few distinct clay films on faces of peds; slightly alkaline; clear wavy boundary. (15 to 41 cm thick)

Btk--38 to 61 cm; pale brown (10YR 6/3) silty clay loam, brown (10YR 4/3) moist; moderate medium prismatic structure; hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; few faint and distinct clay films on faces of peds; slightly effervescent; calcium carbonate disseminated; slightly alkaline; clear wavy boundary. (0 to 30 cm thick)

Bk--61 to 96 cm; very pale brown (10YR 7/3) silty clay loam, brown (10YR 5/3) moist; weak medium prismatic structure; hard,friable, slightly sticky and slightly plastic; few very fine and fine roots; strongly effervescent, calcium carbonate disseminated and few to common fine filaments and nests; moderately alkaline; clear wavy boundary. (15 to 64 cm)

C--96 to 152 cm; very pale brown (10YR 8/3) silt loam, pale brown (10YR 6/3) moist; massive; soft, very friable, slightly sticky and slightly plastic; violently effervescent; calcium carbonate disseminated; moderately alkaline.

TYPE LOCATION: Niobrara County, Wyoming; about 200 feet south and 1,100 feet west of the northeast corner of Sec. 2, T.35 N., R. 62 W. Coyote Gap Quad. 43 degrees 2 minutes 44 seconds north latitude and 104 degrees 15 minutes 57 seconds west longitude; NAD 83.

RANGE IN CHARACTERISTICS:
Mollic epipedon: 15 to 50 cm thick
Base of argillic horizon: 40 to 65 cm
Depth to lime: 25 to 75 cm
Coarse fragments: 0 to 15 percent siltstone and/or sandstone paragravel
Mean annual soil temperature: 9 to 11.5 degrees C


A horizon:
Hue: 10YR or 2.5Y
Value: of 4 or 5 and 2 or 3 moist
Chroma: of 2 or 3
Texture: loam or silt loam
Reaction: slightly acid to slightly alkaline

An AB or BA horizon is present in some pedons.

Bt horizon:
Hue: 10YR or 2.5Y
Value: 4 to 7 and 3 to 5 moist
Chroma: 2 to 4
Texture: loam, sandy clay loam, silt loam, silty clay loam or clay loam
Reaction: neutral to moderately alkaline.

The Btk horizon has properties of both Bt and Btk horizons.

Bk horizon:
Hue: 7.5YR, 10YR, or 2.5Y
Value: 7 or 8 and 5 or 6 moist
Chroma: 2 to 4
Texture: silt loam or silty clay loam
Calcium carbonate equivalent: 3 to 14 percent
Reaction: moderately alkaline or strongly alkaline

C horizon:
Hue: 7.5YR, 10YR, or 2.5Y
Value: 6 to 8 and 5 to 7 moist
Chroma: 2 to 4
Texture: silt, silt loam, loam or very fine sandy loam
Reaction: moderately alkaline or strongly alkaline

COMPETING SERIES:
Aliante soils are drier in late spring and early summer. They do not have accumulations of calcium carbonate in the profile.
Alliance soils have weakly cemented, very fine grain sandstone bedrock at 100 to 150 cm.
Beeler, Cale, Calemore, Hugoton, Keith, and Norka soils have warmer mean annual soil temperatures. Additionally, Beeler soils have accumulations of gypsum and electrical conductivity of 1 to 25 dS/m; the base of the argillic horizon is greater than 66 cm in Calemore soils; Keith soils formed in calcareous loess; and Norka soils have a Bt horizon whose base is at 38 cm or less.
Kadoka and Mace soils have bedrock at 50 to 100 cm
Vale soils formed in material derived from red siltstone, sandstone, or shale from the Spearfish formation

GEOGRAPHIC SETTING:
Landscape: plains, uplands, tableland
Landform: fan remnants, outwash fans, terraces and terrace remnants, and hillslopes
Position: backslope, footslope, toeslope
Slope: 0 to 15 percent
Elevation: 975 to 1,730 meters
Mean annual precipitation: 300 to 460 mm, over half of which falls from mid-March through mid-July
Frost-free season: 110 to 145 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Colby and the competing Kadoka soils.
Colby soils lack a mollic epipedon and an argillic horizon. They occur on similar landform postions as the Thirtynine soil.
Kadoka soils occur on higher landform positions than the Thirtynine soils.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage: Well drained
Runoff: slow to rapid runoff
Saturated hydraulic conductivity: moderately high

USE AND VEGETATION: Thirtynine soils are utilized for livestock grazing, wildlife habitat, and for limited dry cropland and pasture. The native vegetation is mainly western wheatgrass, green needlegrass, blue grama, threadleaf sedge, and bluegrasses. Wheat and alfalfa are the principal cultivated crops.

DISTRIBUTION AND EXTENT: Eastern Wyoming, northwestern Nebraska, and southwestern South Dakota; LRR G, MLRA 64. The series is of moderate extent.

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

SERIES ESTABLISHED: Sioux County, Nebraska; 1993

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon--0 to 20 cm (A1, A2)
Argillic horizon--20 to 60 cm (Bt, Btk)

Taxonomic Version: Keys to Soil Taxonomy, Eleventh edition

ADDITIONAL DATA:

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National Cooperative Soil Survey
U.S.A.