LOCATION OPAL SD

Established Series
DLB-WJB-AAO
07/2013

OPAL SERIES

The Opal series consists of moderately deep, well drained soils formed in clayey sediments weathered from clay shale on dissected upland plains and hills. Slopes range from 0 to 25 percent. Mean annual precipitation is about 460 millimeters (18 inches), and mean annual air temperature is about 8 degrees C (47 degrees F).

TAXONOMIC CLASS: Fine, smectitic, mesic Leptic Haplusterts

TYPICAL PEDON: Opal clay - on a convex, northeast-facing slope of 1 percent under native grass. (Colors are for dry soil unless otherwise stated.) When described on June 4, 1984, the soil was moist to 61 centimeters (24 inches) and dry below.

A--0 to 5 centimeters (0 to 2 inches); grayish brown (10YR 5/2) clay, very dark gray (10YR 3/1) moist; moderate medium and fine granular structure; slightly hard, friable, sticky and plastic; many fine and medium roots; slightly alkaline; clear smooth boundary. [5 to 20 centimeters (2 to 8 inches) thick.]

Bss1--5 to 25 centimeters (2 to 10 inches); grayish brown (2.5Y 5/2) clay, very dark grayish brown (2.5Y 3/2) moist; moderate medium and coarse subangular blocky structure; very hard, firm, very sticky and very plastic; many fine and medium roots; common distinct nonintersecting slickensides; cracks 1.5 centimeters (1/2 inch) wide; 1 percent pebbles; slight effervescence; neutral; clear wavy boundary.

Bss2--25 to 41 centimeters (10 to 16 inches); grayish brown (2.5Y 5/2) clay, very dark grayish brown (2.5Y 3/2) moist; weak coarse prismatic structure parting to moderate medium and coarse subangular blocky; extremely hard, firm, very sticky and very plastic; common fine and medium roots; many prominent intersecting slickensides; cracks 3 centimeters (1 inch) wide; 1 percent pebbles; strong effervescence; moderately alkaline; clear wavy boundary. [Combined Bss horizons 20 to 51 centimeters (8 to 20 inches) thick.]

Bkss--41 to 66 centimeters (16 to 26 inches); light brownish gray (2.5Y 6/2) clay, dark grayish brown (2.5Y 4/2) moist; weak coarse prismatic structure parting to moderate medium and coarse subangular blocky; extremely hard, firm, very sticky and very plastic; few fine roots; many prominent intersecting slickensides; cracks 1.5 to 3 centimeters (1/2 to 1 inch) wide; many fine and medium accumulations of carbonate; 1 percent pebbles; strong effervescence; moderately alkaline; clear wavy boundary. [0 to 38 centimeters (0 to 15 inches) thick.]

Cyz1--66 to 76 centimeters (26 to 30 inches); light brownish gray (2.5Y 6/2) clay, dark grayish brown (2.5Y 4/2) moist; many fine distinct yellowish brown (10YR 5/6) mottles; massive; very hard, firm, very sticky and very plastic; many fine nests of gypsum and other salts; 1 percent pebbles; strong effervescence; moderately alkaline; clear wavy boundary.

Cyz2--76 to 89 centimeters (30 to 35 inches); light brownish gray (2.5Y 6/2) clay, dark grayish brown (2.5Y 4/2) moist; few fine prominent strong brown (7.5YR 5/6) and common fine distinct yellowish brown (10YR 5/6) mottles; massive; hard, friable, very sticky, and very plastic; 55 percent soft shale fragments; many fine and medium nests of gypsum and other salts; strong effervescence; moderately alkaline; clear wavy boundary.

Cr1--89 to 104 centimeters (35 to 41 inches); light brownish gray (2.5Y 6/2) and dark gray (5Y 4/1) soft shale, dark grayish brown (2.5Y 4/2); moist; common fine prominent strong brown (7.5YR 5/6) mottles; many yellowish brown (10YR 5/6) iron stains in cracks and seams; many fine nests of gypsum and other salts; strong effervescence; slightly alkaline; gradual wavy boundary.

Cr2--104 to 152 centimeters (41 to 60 inches); light brownish gray (2.5Y 6/2) and dark gray (5Y 4/1) soft shale, dark grayish brown (2.5Y 4/2) moist; common fine prominent strong brown (7.5YR 5/6) mottles; many yellowish brown (10YR 5/6) iron stains along seams and cracks; few fine nests of salts; slightly alkaline.

TYPE LOCATION: Jones County, South Dakota; about 3.2 kilometers (2 miles) east and 1.6 kilometers (1 mile) north of Murdo; located about 764 meters (2508 feet) south and 483 meters (1585 feet) east of the northwest corner, sec. 28, T. 1 S., R. 29 E.; Draper USGS quad; latitude 43 degrees, 59 minutes, 17.575 seconds North and longitude 100 degrees, 36 minutes, 1.919 seconds West, NAD83.

RANGE IN CHARACTERISTICS:
Soil Moisture Control Section:
The soil moisture control section is moist in some parts from April to July; intermittently moist from October to March; driest in August and September; typic ustic moisture regime.

Soil Temperature: 7 to 11 degrees C (45 to 52 degrees F)

Particle Size Control Section (weighted average):
Clay content: 50 to 59 percent
Sand content: 1 to 10 percent fine sand and coarser

Depth to Bedrock: typically 71 to 89 centimeters (28 to 35) inches and ranges from 50 to 100 centimeters (about 20 to 40 inches)

Fragments: The soil contains partially weathered fine shale fragments ranging from about 0 to 10 percent by volume in the solum and up to 60 percent in the C horizon. Pebbles range from 0 to 5 percent, by volume, throughout the solum.

Cracks: 1.5 to 3 centimeters (1/2 to one inch) wide and 0.6 meters (2 feet) long extend downward through the solum when the soil is dry.

Depth to Carbonates: ranges from 0 to 20 centimeters (0 to 8 inches).

A horizon:
Hue: 10YR, 2.5Y or 5Y
Value: 4 or 5 dry and 2 or 3 moist
Chroma: 1 or 2 dry or moist
Texture: clay or silty clay
Clay content: 45 to 60 percent
Sand content: 2 to 10 percent
Reaction: neutral or slightly alkaline.
Some pedons have a thin, fragile surface crust or mulch.

Bss horizon:
Hue: 2.5Y or 5Y
Value: 4 to 6 dry and 2 to 4 moist
Chroma: 2 or 3 dry or moist
Texture: clay
Clay content: 60 to 70 percent clay
Sand content: 1 to 10 percent
Reaction: neutral to moderately alkaline
Consistence: extremely hard or very hard when dry and extremely firm to firm when moist
Cracks: 1.5 to 3 centimeters (1/2 to one inch) wide

Bkss horizon:
Hue: 2.5Y or 5Y
Value: 4 to 6 dry and 3 to 5 moist
Chroma: 2 to 4
Texture: clay
Clay content: 60 to 70 percent
Sand content: 1 to 10 percent
Reaction: slightly or moderately alkaline
Concentrations: few to many accumulations of carbonate
Cracks: 1.5 to 3 centimeters (1/2 to one inch) wide

C horizon:
Hue: 2.5Y or 5Y
Value: 5 or 6 dry and 4 or 5 moist
Chroma: 1 to 3 dry or moist
Texture: clay or silty clay
Clay content: 50 to 60 percent
Sand content: 1 to 10 percent
Fragments: 1 to 60 percent, pebbles or soft shale fragments by volume
Reaction: slightly acid to moderately alkaline
Electrical Conductivity: 2 mmhos/cm or more.

Cr horizon:
This horizon is made up of soft shale from the Pierre Formation. It is weakly cemented and is strongly acid to moderately alkaline.

COMPETING SERIES: This is the Boyd series. Boyd soils have less than 60 percent clay in the Bss horizons.

GEOGRAPHIC SETTING: Parent material: locally transported clay sediments weathered from soft shale over residuum from clayey marine shale of the Pierre Formation
Landscape: level to moderately steep uplands
Landform: dissected plains and hills
Slopes: 0 to 25 percent
Slope shape: plane or convex
Elevation: 375 to 850 meters (1230 to 2790 feet)
Mean annual air temperature: 6 to 10 degrees C (43 to 50 degrees F)
Mean annual precipitation: 400 to 700 millimeters (16 to 27 inches)
Microrelief: Gilgai microrelief is in most areas.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bullcreek, Chantier, Dupree, Hurley, Lakoma, Promise, and Sansarc soils. Bullcreek and Promise soils are on toeslopes and flats below the Opal soils. They are more than 100 centimeters (about 40 inches) deep to shale. Chantier soils are on steeper landscapes. They do not have mollic epipedons and contain more salts. Dupree and Sansarc soils typically are on steeper areas on the landscape. They have bedrock at depths of 25 to 50 centimeters (about 10 to 20 inches). Hurley soils are on less sloping landscapes. They have a natric horizon. Lakoma soils are on similar landscapes. They do not have a mollic epipedon or intersecting slickensides.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage: Well drained
Saturated Hydraulic Conductivity: Moderately low
Surface Runoff: medium to very high depending on slope

USE AND VEGETATION: Cropland and grazing land. Winter wheat, alfalfa, and sorghum are the principal crops. Native vegetation is mainly western wheatgrass, green needlegrass, blue grama, sideoats grama, and sedges.

DISTRIBUTION AND EXTENT: Central South Dakota, mostly west of the Missouri River; Land Resource Region F, Northern Great Plains Spring Wheat Region and Land Resource Region G, Western Great Plains Range and Irrigated Region, Major Land Resource Area 54, 63A, and 63B. The soil is extensive.

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

SERIES ESTABLISHED: Hughes County, South Dakota, 1970.

REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 41 centimeters [16 inches (A, Bss1 and Bss2 horizons)] ; Vertisol criteria - cracks to a depth of 66 centimeters [26 inches (Bss1, Bss2, and Bkss horizons)] and intersecting slickensides (Bss2 and Bkss horizons); Paralithic contact - the soft shale contact from 89 to 152 centimeters [35 to 60 inches (Cr1 and Cr2 horizons)].
Taxonomic Version: Eleventh Edition, 2010.

AAO 6/2013 Updated the Range in Characteristics, type location description, distribution and extent, geographic setting, associated soils, and saturated hydraulic conductivity; added metric units to all measurements and temperatures, and changed format to tabular.

ADDITIONAL DATA:

National Cooperative Soil Survey
U.S.A.