LOCATION STRADDLEBUG TX

Established Series
Rev. LEL/JLR/ACT
10/2012

STRADDLEBUG SERIES

The Straddlebug series consists of very deep, well drained, moderately slowly permeable soils on broad alluvial flats and floodplains. These nearly level to gently sloping soils formed in loamy alluvium derived mainly from tuffs of the Duff and Pruett Formations. Slopes range from 0 to 3 percent.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Sodic Ustic Haplocambids

TYPICAL PEDON: Straddlebug silty clay loam - rangeland. (Colors are for dry soil unless otherwise stated.)

A1--0 to 4 inches; pinkish gray (7.5YR 6/2) silty clay loam, brown (7.5YR 4/2) moist; moderate medium subangular blocky parting to weak thin platy structure; hard, firm, moderately sticky and moderately plastic; common fine and medium roots; common very fine and fine interstitial pores; 1 percent subangular gravel; 4 percent calcium carbonate equivalent; violently effervescent; nonsaline, moderately alkaline; abrupt smooth boundary. (3 to 9 inches thick)

A2--4 to 11 inches; brown (7.5YR 5/2) clay, dark brown (7.5YR 3/2) moist; weak coarse prismatic parting to moderate medium and coarse angular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine, fine, and coarse roots; common very fine and fine tubular pores; 1 percent subangular gravel; 7 percent calcium carbonate equivalent; violently effervescent; nonsaline, moderately alkaline; gradual smooth boundary. (4 to 12 inches thick)

Bn--11 to 18 inches; brown (7.5YR 5/2) clay, brown (7.5YR 4/2) moist; weak coarse prismatic parting to moderate medium and coarse angular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine and fine roots; few very fine tubular pores; 2 percent subangular gravel; 9 percent calcium carbonate equivalent; violently effervescent; nonsaline, moderately alkaline; clear smooth boundary. (6 to 12 inches thick)

Bkn1--18 to 26 inches; brown (7.5YR 5/3) clay loam, brown (7.5YR 4/3) moist; weak medium and coarse subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine roots; common very fine tubular pores; very few prominent discontinuous white (10YR 8/1) coatings of calcium carbonate on surfaces of peds; common medium masses of calcium carbonate; 5 percent subangular gravel; 11 percent calcium carbonate equivalent; violently effervescent; very slightly saline, moderately alkaline; clear smooth boundary.

Bkn2--26 to 33 inches; light brown (7.5YR 6/3) sandy clay loam, brown (7.5YR 5/3) moist; weak medium and coarse subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine roots; common very fine and fine tubular pores; very few prominent discontinuous white (10YR 8/1) coatings of calcium carbonate on surfaces of peds; common fine masses of calcium carbonate; 3 percent subangular gravel; 12 percent calcium carbonate equivalent; violently effervescent; very slightly saline, moderately alkaline; gradual smooth boundary.

Bkn3--33 to 46 inches; light brown (7.5YR 6/3) fine sandy loam, brown (7.5YR 5/3) moist; weak medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; few very fine tubular pores; very few prominent discontinuous white (10YR 8/1) coatings of calcium carbonate on surfaces of peds; common medium masses of calcium carbonate; 6 percent calcium carbonate equivalent; 5 percent subangular gravel; violently effervescent; slightly saline, moderately alkaline; gradual smooth boundary.

Bkn4--46 to 58 inches; light brown (7.5YR 6/3) fine sandy loam, brown (7.5YR 5/3) moist; weak medium and coarse subangular blocky structure; slightly hard, friable; few very fine roots; few very fine tubular pores; very few prominent discontinuous white (10YR 8/1) coatings of calcium carbonate on surfaces of peds; common medium masses of calcium carbonate; 5 percent subangular gravel; 9 percent calcium carbonate equivalent; violently effervescent; moderately saline, moderately alkaline; gradual smooth boundary.

Bkn5--58 to 80 inches; light brown (7.5YR 6/3) sandy clay loam, brown (7.5YR 5/3) moist; weak medium and coarse subangular blocky structure; slightly hard, firm slightly sticky and slightly plastic; few very fine roots; few very fine tubular pores; very few prominent discontinuous white (10YR 8/1) coatings of calcium carbonate on surfaces of peds; common medium masses of calcium carbonate; 2 percent subangular gravel; 7 percent calcium carbonate equivalent; violently effervescent; slightly saline, moderately alkaline. (Combined thickness of Bk horizons is 35 to 60 inches)

TYPE LOCATION: Brewster County, Texas; from the junction of U.S. Highway 90 and Texas Highway 118 in Alpine, 32.3 miles south on Texas Highway 118, 7.7 miles west-southwest on 02 Ranch headquarters road, 0.25 mile north on ranch road east of "The Ditch", 500 feet northwest of corner of road in rangeland. USGS Duff Springs 7.5 minute topographic quadrangle. Latitude: 29 degrees, 53 minutes, 6 seconds North; Longitude: 103 degrees, 41 minutes, 14 seconds West; NAD83. UTM coordinates: 626766 m E, 3306766 m N, Zone 13.

RANGE IN CHARACTERISTICS:

Soil Moisture: Ustic aridic soil moisture regime

Solum thickness: greater than 80 inches

Clay content in the control section: 25 to 35 percent

Rock fragments: less than 15 percent, but individual strata may contain up to 35 percent

Reaction: moderately alkaline

Sodium adsorption ratio: 13 to 30 percent in the upper part and 20 to 35 in the lower part

A1 horizon
Hue: 7.5YR, 10YR
Value: 6 or 7 dry, 4 moist
Chroma: 2 through 4, dry or moist
Texture: loam, clay loam, silty clay loam
Clay content: 27 to 40 percent
Rock fragments: 0 to 5 percent
Calcium carbonate equivalent: 1 to 10 percent

A2 horizon
Hue: 7.5YR, 10YR
Value: 4 through 6 dry, 3 moist
Chroma: 2 through 4, dry or moist
Texture: silty clay loam, clay loam, clay
Clay content: 27 to 35 percent
Rock fragments: 0 to 5 percent
Calcium carbonate equivalent: 1 to 10 percent

Bn horizons
Hue: 7.5YR, 10YR
Value: 5 through 7 dry, 4 moist
Chroma: 2 through 4, dry or moist
Texture: clay loam, silty clay loam, clay
Rock fragments: 0 to 10 percent
Calcium carbonate equivalent: 1 to 10 percent

Bkn horizons
Hue: 7.5YR, 10YR
Value: 5 through 7 dry, 4 or 5 moist
Chroma: 2 through 4, dry or moist
Texture: stratified with thin layers of contrasting textures that range from loamy coarse sand to silty clay
Rock fragments: 0 to 15 percent, but individual thin strata may contain up to 45 percent
Calcium carbonate equivalent: 2 to 15 percent

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Straddlebug soils are on broad alluvial flats and floodplains. These soils formed in loamy alluvium derived mainly from tuffs of the Duff and Pruett Formations. Slopes range from 0 to 3 percent. Mean annual precipitation is 10 to 15 inches, with most occurring in the summer months. Mean annual air temperature ranges from 62 to 68 degrees F. Frost-free period ranges from 210 to 260 days, and elevation is 3,500 to 5,000 feet.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Borunda, Butcherknife, and Gemelo soils. Borunda soils are moderately deep to tuffaceous bedrock, and have calcic and gypsic horizons. They are on convex erosional uplands. Butcherknife soils have calcic and gypsic horizons, and are in the fine family. They are on broad alluvial flats. Gemelo soils are in the coarse-loamy family, and are on alluvial fan aprons.

DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately slow. Runoff is low on 0 to 1 percent slopes, and medium on 1 to 3 percent slopes.

USE AND VEGETATION: This soil is used as livestock grazing and wildlife habitat. Woody species include tarbush, creosotebush, and mesquite. Grasses include tobosagrass, blue grama, black grama, sideoats grama, bush muhly, burrograss, plains bristlegrass, Arizona cottontop, alkali sacaton, and cane bluestem.

DISTRIBUTION AND EXTENT: West Texas. MLRA 42. The series is moderately extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona

SERIES ESTABLISHED: Brewster County, Texas, 1997. The name is from a mountain in the area.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - the zone from 0 to 4 inches (A1 horizon)

Cambic horizon - the zone from 11 to 80 inches (Bn and Bkn horizons)

Ustic feature - the soil has an aridic moisture regime that borders the ustic moisture regime.

Sodic feature - Sodium Adsorption Ratio (SAR) of greater than 13 in a horizon at least 10 inches thick within 40 inches of the surface.

Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Eleventh Edition, 2010

Update and revisions for the recorrelation of Brewster County, Texas, Main part, 2/12/2008, CEM

Revised for the correlation of Presidio County, Texas ; Oct, 2012, WWJ

ADDITIONAL DATA: Classification change from Ustifluventic Haplocambids to Sodic Ustic Haplocambids based on TAMU laboratory data (S93TX-377-007) from Presidio County, Texas, and a NSSL reference sample (S95TX-043-013) from the type location in Brewster County, Texas.

National Cooperative Soil Survey
U.S.A.