LOCATION SEFERINO TXEstablished Series
TAXONOMIC CLASS: Fine-silty, carbonatic, hyperthermic Ustic Haplocalcids
TYPICAL PEDON: Seferino silty clay loam--rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 8 cm (0 to 3 inches); pale brown (10YR 6/3) silty clay loam, brown (10YR 5/3) moist; moderate medium granular structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; common very fine and fine interstitial and tubular pores; strongly effervescent, moderately alkaline; abrupt smooth boundary. 5 to 25 cm (2 to 10 inches) thick.
Bw1--8 to 20 cm (3 to 8 inches); light brown (7.5YR 6/4) silty clay loam, brown (7.5YR 5/4) moist; moderate fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; common very fine and fine tubular pores; strongly effervescent; moderately alkaline; clear smooth boundary. 8 to 15 cm (3 to 6 inches) thick
Bw2--20 to 41 cm (8 to 16 inches); light brown (7.5YR 6/4) silty clay, brown (7.5YR 5/4) moist; moderate medium subangular blocky structure; hard, firm, very moderately sticky and moderately plastic; common very fine and fine roots; common very fine and fine tubular pores; strongly effervescent; moderately alkaline. 0 to 31 cm (0 to 12 inches) thick
Bk1--41 to 69 cm (16 to 27 inches); pink (7.5YR 7/4) silty clay, brown (7.5YR 5/4) moist; moderate fine subangular blocky structure; hard, firm, very moderately sticky and moderately plastic; few very fine and fine roots; common very fine and fine tubular pores; few films and threads of calcium carbonate; strongly effervescent; moderately alkaline; gradual wavy boundary.
Bk2--69 to 102 cm (27 to 40 inches); pink (7.5YR 7/4) silty clay, brown (7.5YR 5/4) moist; weak fine subangular blocky structure; hard, firm, very moderately sticky and moderately plastic; common very fine and fine tubular pores; common fine threads and masses of calcium carbonate; strongly effervescent; moderately alkaline; gradual wavy boundary.
Bk3--102 to 173 cm (40 to 68 inches); pink (7.5YR 7/4) silty clay, brown (7.5YR 5/4) moist; weak fine subangular blocky structure; hard, firm, very moderately sticky and moderately plastic; common very fine and fine tubular pores; common fine threads and masses of calcium carbonate; violently effervescent; moderately alkaline; gradual wavy boundary.
Bk4--173 to 203 cm (68 to 80 inches); pink (7.5YR 7/4) silty clay, brown (7.5YR 5/4) moist; weak fine subangular blocky structure; hard, firm, very moderately sticky and moderately plastic; common very fine and fine tubular pores; few films and threads of calcium carbonate; violently effervescent; moderately alkaline. (Combined thickness of Bk horizons is 157 to 203 cm (50 to 80 inches))
TYPE LOCATION: Brewster County, Texas; from the junction of U. S. Highways 90 and 385 just east of Marathon; 30.8 miles south on U. S. Highway 385 to Dove Mountain Road; 22.5 miles east on Dove Mountain Road; 100 feet north in range. (Latitude: 29 minutes, 47 minutes, 39 seconds North; Longitude: 102 minutes, 49 minutes, 09 seconds West, NAD 1927; Dove Mountain USGS 7.5 minute topographic quadrangle)
RANGE IN CHARACTERISTICS:
Soil moisture: The moisture control section is dry in all parts more than three fourths of the time the soil temperature exceeds 5.0 degrees C (41 degrees F). Intermittently moist in some part of the soil moisture control section during June to September. More than 60 percent of the annual rainfall occurs during that period. The soil does not receive significant amounts of moisture during winter months. Ustic aridic soil moisture regime.
Mean annual soil temperature: 22.0 to 25.6 degrees C (72 to 78 degrees F).
Depth to calcic horizon: 12 to 30 inches
Particle size control section (weighted average):
Total clay content: 35 to 50 percent
Silicate clay content: 20 to 35 percent
Coarser than very fine sand content: less than 15 percent
Rock fragment content: 0 to 2 percent gravel
Calcium carbonate equivalent: 40 to 50 percent
A horizon:
Hue: 7.5YR or 10YR
Value: 4 to 7, dry' 3 to 6, moist
Chroma: 2 to 4, dry or moist
Texture: silt loam or silty clay loam
Total clay content: 20 to 35 percent
Silicate clay content: 15 to 30 percent
Calcium carbonate equivalent: 30 to 40 percent
Bw horizon:
Hue: 7.5YR or 10YR
Value: 5 to 7, dry; 4 to 6, moist
Chroma: 2 to 4, dry or moist
Texture: silty clay loam or silty clay
Calcium carbonate: none to few in the form of films, threads and masses
Bk1, Bk2, Bk3 horizons:
Hue: 5YR to 10YR
Value: 6 to 8, dry; 5 to 7, moist
Chroma: 2 to 6, dry or moist
Texture: silty clay loam or silty clay
Calcium carbonate concentrations: common to many films, threads, concretions and masses
Bk4 horizon:
Color: similar to the upper Bk horizon
Texture: similar to the upper Bk horizon
Total clay content: 35 to 45 percent
Silicate clay content: 25 to 35 percent
Calcium carbonate concentrations: few to common films, threads, concretions and masses
Calcium carbonate equivalent: 30 to 50 percent by volume
COMPETING SERIES: This includes the Coahuila (TX) series. Coahuila soils occur at elevation less than 1800 feet.
GEOGRAPHIC SETTING:
Parent material: fine-silty alluvium and residuum derived from limestone.
Landform: broad, nearly level to gently sloping alluvial flats and fan skirts
Slope: 0 to 3 percent, mostly less than 2 percent.
Mean annual air temperature: 20.0 to 22.2 degrees C (68 to 72 degrees F)
Mean annual precipitation: 254 to 330 mm (10 to 13 inches)
Precipitation pattern: Most precipitation occurs as high intensity rainfall during convectional afternoon thunderstorms from June through September. Precipitation during the months of January, February, and March is less than 13 percent of the total.
Frost free period: 240 to 280 days
Elevation: 610 to 1067 meters (2000 to 3500 feet).
GEOGRAPHICALLY ASSOCIATED SOILS: These include the
Blackgap,
Sanderson, and
Upton series.
Blackgap soils are less than 20 inches to a lithic contact and are on surrounding hills and mountains.
Sanderson soils have loamy-skeletal control sections and are on higher fan and footslope landforms near hills and mountains.
Upton soils have a petrocalcic horizon within 20 inches of the surface and are on fans and footslopes on higher, older landforms.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate. Runoff is negligible on slopes less than 1 percent, and very low on 1 to 3 percent slopes.
USE AND VEGETATION: Mainly used for rangeland. Native vegetation consists of black grama, dropseeds, bush muhly, tobosa, blue grama, plains bristlegrass, threeawn javalinabush and Yucca.
DISTRIBUTION AND EXTENT: Far west Texas; LRR I, MLRA 81D, Southern Edwards Plateau. The series is of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Brewster County, Texas, 1997. The name is from a canyon in the area.
REMARKS: MLRA Office responsible changed from Phoenix, Arizona, to Temple, Texas because type location is within MLRA 81D, Southern Edwards Plateau.
Soil temperature regime classification changed from thermic to hyperthermic based on the summary of a 6-year soil temperature study in Far West Texas. Taxonomic class and moisture regime classification changed from typic aridic to ustic aridic.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: 0 to 8 cm (0 to 3 inches). (A horizon)
Cambic horizon: 8 to 41 cm (3 to 16 inches). (Bw horizons)
Calcic horizon: 41 to 173 cm (16 to 68 inches). (Bk1, Bk2 and Bk3 horizons)
Seferino soils were previously included in the Reakor series.
ADDITIONAL DATA: National Soil Survey Laboratory characterization data are available for 2 pedons; samples S91TX-043-003 and S91TX-043-206.
TAXONOMIC VERSION: Keys to Soil Taxonomy, Tenth Edition, 2006