LOCATION OBARO                   TX+KS OK

Established Series
Rev. WER-ERB-DDR
12/2018

OBARO SERIES

The Obaro series consists of moderately deep, well drained, moderately permeable soils that formed in residuum of weakly consolidated, noncemented, fine-grained calcareous sandstone of the Quartermaster Formation and Whitehorse group of Permian age. These soils occur on very gently sloping to moderately steep interfluves and side slopes of hillslopes, knolls, and ridges in the Central Rolling Red Plains. Slope ranges from 1 to 15 percent. Mean annual precipitation is 559 mm (22 in) and mean annual air temperature is 16.1 degrees C (61 degrees F).

TAXONOMIC CLASS: Fine-silty, mixed, superactive, thermic Typic Haplustepts

TYPICAL PEDON: Obaro loam, on east-facing, convex, 2 percent slope in rangeland at an elevation of about 646 m (2,120 feet).
(Colors are for dry soil unless otherwise stated.)

A--0 to 20 cm (0 to 8 in); reddish brown (5YR 5/4) loam, dark reddish brown (5YR 3/4) moist; weak subangular blocky structure; slightly hard, very friable; many roots; few calcium carbonate coated sandstone fragments on surface and within horizon; strongly effervescent; moderately alkaline; clear smooth boundary. Thickness of the A horizon is 13 to 38 cm (5 to 15 in)

Bk1--20 to 46 cm (8 to 18 in); reddish brown (2.5YR 5/4) loam, dark reddish brown (2.5YR 3/4) moist; weak prismatic structure parting to moderate medium subangular blocky; slightly hard, very friable; many fine roots; many fine pores; common wormcasts; about 3 percent of less than 1 inch in diameter pararock fragments consisting of weakly to moderately cemented sandstone; few films and threads of calcium carbonate; violently effervescent; moderately alkaline; gradual smooth boundary. Thickness of the Bk1 horizon is 18 to 56 cm (7 to 22 in)

Bk2--46 to 76 cm (18 to 30 in); light red (2.5YR 6/6) loam, red (2.5YR 4/6) moist; compound, weak prismatic structure parting to moderate medium subangular blocky; hard, very friable; few roots; less than 1 inch in diameter pararock fragments consisting of weakly to moderately cemented sandstone; few films and masses of calcium carbonate and few carbonate coatings on sandstone fragments; violently effervescent; moderately alkaline; clear smooth boundary. Thickness of the Bk2 horizon is 10 to 48 cm (4 to 19 in)

Cd--76 to 152 cm (30 to 60 in); red (2.5YR 5/6) weakly consolidated, noncemented calcareous sandstone, dark red (2.5YR 3/6) moist; common fine distinct bluish green mottles.

TYPE LOCATION:
Kent County, Texas; From the intersection of Texas Highway 208 and U.S. Highway 380 in Clairemont, 2.6 miles east of Clairemont on U.S. Highway 380, 2.1 miles north on ranch road, then 50 feet east in rangeland.

USGS topographic quadrangle: Clairemont East, OK
Latitude: 33 degrees, 11 minutes, 16 seconds N
Longitude: 100 degrees, 42 minutes, 30 seconds W
Datum: NAD83

Decimal Degrees
Std Latitude: 33.1877777
Std Longitude: -100.7083333

UTM Northing: 3673404 m
UTM Easting: 3407440 m
UTM Zone: 14N

RANGE IN CHARACTERISTICS:
Soil moisture: A typic-ustic moisture regime.
Solum thickness: 51 to 102 cm (20 to 40 in)
Depth to densic bedrock: 51 to 102 cm (20 to 40 in)
Depth to secondary carbonates: 15 to 51 cm (6 to 20 in)
Depth to cambic horizon: 13 to 38 cm (5 to 15 in)

Particle-size control section (weighted average):
Total clay content: 18 to 35 percent
Carbonate clay content: 0 to 3 percent

A horizon:
Hue: 5YR, 7.5YR
Value: 4 to 5 dry, 3 to 5 moist
Chroma: 3 to 4
Texture: very fine sandy loam, loam, clay loam, silt loam, silty clay loam
Total clay content: 10 to 35 percent
Identifiable secondary carbonate: 0 to 5 percent as threads, masses, and nodules.
Calcium carbonate equivalent: 0 to 15 percent by weight
Effervescence: slight to violent
Reaction (pH): slightly alkaline to moderately alkaline (7.4-8.4)

Bw or upper Bk horizon:
Hue: 2.5YR, 5YR
Value: 4 to 6 dry, 3 to 5 moist
Chroma: 4 to 6
Texture: very fine sandy loam, loam, clay loam, silt loam, silty clay loam
Total clay content: 18 to 35 percent
Carbonate clay content: 0 to 3 percent
Pararock fragments: 0 to 10 percent; 2 to 20 mm; very weakly to moderately cemented sandstone
Identifiable secondary carbonate: 0 to 5 percent in the form of threads, masses, and nodules
Calcium carbonate equivalent (CCE): 1 to 20 percent
Effervescence: strong to violent
Reaction (pH): slightly alkaline to moderately alkaline (7.4-8.4)

Lower Bk horizon:
Hue: 2.5YR, 5YR
Value: 4 to 6 dry, 3 to 5 moist
Chroma: 4 to 8
Texture: very fine sandy loam, loam, clay loam, silt loam, silty clay loam
Total clay content: 18 to 35 percent
Carbonate clay content: 0 to 3 percent
Pararock fragments: 0 to 10 percent; 2 to 20 mm; very weakly to moderately cemented sandstone
Identifiable secondary carbonate: 2 to 35 percent in the form of films, threads, and masses
Calcium carbonate equivalent (CCE): 3 to 20 percent
Effervescence: strong to violent
Reaction (pH): slightly alkaline to moderately alkaline (7.4-8.4)

Cd horizon:
Hue: 2.5YR, 5YR
Value 3 to 6 dry or moist
Chroma 4 to 8
Bedrock: ranges from noncemented to extremely weakly cemented calcareous sandstone or siltstone
Texture: very fine sandy loam, loam, clay loam, silt loam, silty clay loam
Total clay content: 5 to 30 percent
Pararock fragments: 0 to 15 percent 2 to 75 mm; 0 to 2 percent 75 to 250 mm; very weakly to moderately cemented sandstone
Calcium carbonate equivalent (CCE): 1 to 15 percent
Reaction (pH): slightly alkaline to moderately alkaline (7.4-8.4)

COMPETING SERIES:
These are the Burford and Jaywi series in the same family. Similar soils include the Aspermont, Lutie, Vernon, Weymouth, and Woodward series.
Aspermont soils: have a calcic horizon and are more than 102 cm (40 in) deep to bedrock
Burford soils: have a lithologic discontinuity in the lower part and are more than 102 cm (40 in) deep to bedrock
Jaywi soils: formed in calcareous colluvium and are very deep to bedrock
Lutie soils: have a mollic epipedon
Vernon soils: have greater than 35 percent clay in the particle-size control section
Weymouth soils: have a calcic horizon and a fine-loamy particle-size control section
Woodward soils: have less than 18 percent clay in the particle-size control section

GEOGRAPHIC SETTING:
Parent material: residuum derived from noncemented to extremely weakly cemented, fine-grained calcareous sandstone or siltstone, primarily of the Quartermaster Formation and Whitehorse group of Permian age
Landscape: dissected plains
Landform: interfluves and side slopes of hillslopes, knolls, and ridges
Slopes: 1 to 15 percent
Precipitation pattern: These soils are intermittently moist in September through November and March through June. July through August and December through February are the driest months.
Mean annual precipitation: 508 to 762 mm (20 to 30 in)
Thornthwaite annual P-E Index Values: 30 to 44
Mean annual air temperature: 13.9 to 17.8 degrees C (57 to 64 degrees F)
Frost-free period: 180 to 230 days
Elevation: 396.2 to 823.0 m (1,300 to 2,700 feet)

GEOGRAPHICALLY ASSOCIATED SOILS:
These are the Aspermont, Carey, Quinlan, Weymouth, and Woodward series.
Aspermont soils: occur on lower positions and have a calcic horizon
Carey soils: occur on slightly higher positions and have a mollic epipedon and an argillic horizon
Quinlan soils: occur on similar positions and are shallow to sandstone bedrock
Weymouth soils: occur on slightly higher positions and have a calcic horizon
Woodward soils: occur on similar positions and have less than 18 percent clay in the particle-size control section

DRAINAGE AND PERMEABILITY:
Drainage class: Well drained
Permeability class: Moderate
Runoff class: low on 1 to 5 percent slopes and medium on 5 to 15 percent slopes

USE AND VEGETATION:
Major uses: Most is used for livestock grazing but many areas on lesser slopes is used for crop production.
Native vegetation: mainly little bluestem, sideoats grama, blue grama, sand dropseed, and buffalograss
Ecological sites assigned to phases and components of this series are listed below. Current ecological site assignments are in Web Soil Survey. Components of this series include the following ecological sites: Loamy Upland

DISTRIBUTION AND EXTENT:
General area: Western Oklahoma, a few counties in southern Kansas, and northwestern Texas
Land Resource Region: H - Central Great Plains Winter Wheat and Range Region
MLRA 78B & 78C - Central Rolling Red Plains, Western and Eastern Parts
Extent: Large

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Stonewall County, Texas; 1970.

REMARKS:
Obaro soils were formerly included in the Woodward series

Diagnostic horizons and features recognized in this pedon are:
Particle-size control section: 25 to 76 cm (10 to 30_in)
Ochric epipedon: 0 to 20 cm (0 to 8 in) (A horizon)
Cambic horizon: 20 to 76 cm (8 to 30 in) (Bk horizons)
Densic bedrock: occurs at 76 cm (30 in)

Taxonomic version: Keys to Soil Taxonomy, Twelfth Edition, 2014.

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National Cooperative Soil Survey
U.S.A.