LOCATION ORELLA                  NE+SD WY

Established Series
Rev JWW
08/2011

ORELLA SERIES

The Orella series consists of shallow, well drained soils formed in residuum from sodium-enriched claystone on pediment surfaces in badlands landscapes. Slopes range from 1 to 45 percent. Mean annual precipitation is about 405 mm, and the mean annual air temperature is about 9 degrees C.

TAXONOMIC CLASS: Clayey, smectitic, calcareous, mesic, shallow Aridic Ustorthents

TYPICAL PEDON: Orella clay, on a southwest facing slope of 14 percent, in native grass. When described the soil was dry in the surface layer and slightly moist below. (Colors are for dry soil unless otherwise stated)

A--0 to 3 cm; light brownish gray (2.5Y 6/2) clay, dark grayish brown (2.5Y 4/2) moist; weak coarse granular structure; extremely hard, firm, moderately sticky and very plastic; common very fine, few fine roots throughout; few fine discontinuous pores; common trans-horizon cracks 0.5 to 1 cm wide; strongly effervescent; slightly alkaline; abrupt smooth boundary. (2 to 13 cm thick)

C1--3 to 20 cm; light olive gray (5Y 6/2) parachannery clay, olive (5Y 5/3) moist; massive; extremely hard, very firm, very sticky and very plastic; few very fine roots; few very fine discontinuous pores; 20 percent weakly cemented angular claystone channers; common distinct to prominent, fine and medium spherical masses of salts; common trans-horizon cracks 0.5 to 1 cm wide; slightly effervescent; moderately alkaline; clear smooth boundary.

C2--20 to 47 cm; light olive gray (5Y 6/2) extremely parachannery clay, olive gray (5Y 5/2) moist; massive; very hard, firm, moderately sticky and very plastic; few very fine roots; 75 percent weakly cemented angular claystone channers; few faint fine and medium spherical and irregularly-shaped bodies of salts; very slightly effervescent; slightly alkaline, gradual smooth boundary. (Combined thickness of the C horizon is 8 to 46 cm)

Cr--47 to 200 cm; gray (5Y 5/1) to pale olive (5Y 6/3) weakly to moderately cemented claystone of the Chadron formation of the White River group; stratification and vertical fracturing produces medium to coarse angular blocks; prominent strong brown (7.5YR 5/6) to reddish yellow (7.5YR 6/6) dry staining occurs on 5 to 10 percent of fragment surfaces; noneffervescent to very slightly effervescent; strongly alkaline.

TYPE LOCATION: Pennington County, South Dakota; about 12 miles south-southwest of Wall; 320 feet east and 1,100 feet south of the northwest corner of Sec. 15, T. 2 S., R. 14E.; 43 degrees, 52 minutes, 35.7 seconds north latitude, and 102 degrees, 26 minutes, 11.8 seconds west longitude; NAD 83.

RANGE IN CHARACTERISTICS:
Depth to bedrock: 15 to 50 cm
Depth to carbonates: 0 to 25 cm
Clay (control section average): 35 to 70 percent
Surface fragments: 0 to 50 percent; fragments are typically angular chert and/or chalcedony, but may include semi-rounded and rounded rocks of mixed origin

A Horizon:
Hue: 7.5YR, 10YR, 2.5Y, or 5Y
Value: 5 to 7, 4 or 5 moist
Chroma: 1 to 4
Texture: L, SIL, SICL, CL, SIC, C
Sodium Adsorption Ratio: 8 to 15
Reaction: slightly alkaline to strongly alkaline

An AC horizon occurs in some pedons.

C Horizon:
Hue: 7.5YR, 10YR, 2.5Y, or 5Y
Value: 5 to 7, 4 to 6 moist
Chroma: 2 to 4
Texture: SICL, CL, SIC, C
Electrical conductivity: 1 to 8 mmhos
Sodium Adsorption Ratio: 13 to 30
Reaction: slightly alkaline to very strongly alkaline

COMPETING SERIES: These are the Epsie, Samsil and Zigzag soils.
The Epsie, Samsil, and Zigzap soils have SARs less than 13. These soils formed in material derived from Cretaceous shale. Additionally Epsie have electrical conductivity greater than 16 mmhos.

GEOGRAPHIC SETTING:
Parent Material: residuum derived from sodium-enriched claystone of the Chadron formation of the White River Group
Landform: badland pediments, uplands
Slopes: 1 to 45 percent
Elevation: 850 to 1,500 meters
Mean annual air temperature: 6 to 11 degrees C
Mean annual precipitation: 330 to 455 mm
Frost-free period: 130 to 160 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Denby, Fairburn, Interior and Whitewater soils.
Denby and Interior soils are very deep. They occur on terraces and floodplains below Orella soils.
Fairburn soils are loamy and have lower sodium contents. They on similar landscape positions as Orella soils.
Whitewater soils are moderately deep. They occur on terraces below Orella soils.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; moderately-low and low saturated hydraulic conductivity; rapid to very rapid runoff.

USE AND VEGETATION: Areas of these soils are used for livestock grazing and wildlife habitat. Native vegetation consists of western wheatgrass, little bluestem, blue grama, and sideoats grama. Grass stands are sparse to moderate.

DISTRIBUTION AND EXTENT: Southwestern South Dakota and Northwestern Nebraska; LRR G, MLRA 64. The series is extensive.

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

SERIES ESTABLISHED: The Reconnaissance Soil Survey of Western Nebraska, 1911.

REMARKS:
Diagnostic horizons and other features recognized in this pedon are:
Ochric epipedon - 0 to 3 cm (A horizon)
Paralithic materials - 47 to 200 cm (Cr horizon)

Orella soils mapped in central and northeastern Wyoming occur over different geologic formations and are in a drier climatic regime than is typical for the series.

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

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National Cooperative Soil Survey
U.S.A.