LOCATION BRACKETT TX+OKEstablished Series
TAXONOMIC CLASS: Loamy, carbonatic, thermic, shallow Typic Haplustepts
TYPICAL PEDON: Brackett paragravelly clay loam on rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 15 cm (0 to 6 in); grayish brown (10YR 5/2) paragravelly clay loam, dark grayish brown (10YR 4/2) moist; moderate fine subangular blocky and granular structure; hard, friable; common fine roots; few masses and nodules of calcium carbonate; 15 percent weakly cemented limestone gravel; violently effervescent; moderately alkaline; clear smooth boundary. (Thickness of the A horizon is 8 to 30 cm [3 to 12 in])
Bk--15 to 36 cm (6 to 14 in); light gray (10YR 7/2) paragravelly clay loam, light brownish gray (10YR 6/2) moist; moderate fine subangular blocky and granular structure; hard, friable; common fine roots; few masses and nodules of calcium carbonate; 20 percent weakly cemented limestone gravel; violently effervescent; moderately alkaline; clear wavy boundary. (Thickness of the Bk horizon is 8 to 41 cm [3 to 16 in])
Cr--36 to 152 cm (14 to 60 in); weakly cemented, fractured and weathered limestone bedrock with vertical fractures that roots can enter, 10 to 25 cm (4 to 10 in) apart, interbedded with thin strata of pale yellow (2.5Y 7/3) and very pale brown (10YR 7/4) weathered chalk bedrock; moderately alkaline.
TYPE LOCATION: Hays County, Texas; from the intersection of Ranch Road 32 and Ranch Road 12 about 10 miles west of San Marcos, 6 miles west on Ranch Road 32 and 1,000 feet north of the road in rangeland. (Devils Backbone USGS topographic quadrangle; Latitude: 30 degrees, 3 minutes, 57.8 seconds N; Longitude: 98 degrees 11 minutes 18.4 seconds W; NAD83)
RANGE IN CHARACTERISTICS:
Depth to paralithic contact: 13 to 50 cm (5 to 20 in)
Pararock and rock fragments above the paralithic contact: Amount-0 to 34 percent, size-2 to 250 mm, kind-limestone
Effervescence: Strongly to violently
Calcium Carbonate Equivalent: 40 to 85 percent by weight
Reaction: Slightly alkaline or moderately alkaline
Particle-size control section (weighted average):
Silicate clay content: 18 to 30 percent
Carbonate clay content: 2 to 10 percent
A horizon
Hue: 10YR or 2.5Y
Value: 5 to 8
Chroma: 2 to 4
Texture: Loam or clay loam; and paragravelly and gravelly modifiers
Pararock and rock fragments: Amount-0 to 34 percent by volume, size-2 to 250 mm, kind-limestone
Other features: Where dry value is 5 or more, the organic carbon content is less than 2.5 percent
Bk horizon
Hue: 7.5YR to 2.5Y
Value: 5 to 8
Chroma: 2 to 4
Texture: Silt loam, loam, silty clay loam, or clay loam; and paragravelly and gravelly modifiers
Pararock and rock fragments: Amount-0 to 34 percent by volume, size-2 to 250 mm, kind-limestone
Identifiable secondary carbonate: Amount-1 to 4 percent by volume; kind-masses, concretions or nodules, location-around rock fragments, in the matrix, and throughout
Mottle features: brownish or grayish mottles in the matrix and along faces of peds and within porous limestone fragments in some pedons.
Cr layer
Hue: 10YR or 2.5Y
Value: 7 or 8
Chroma: 2 to 4
Other features: Secondary carbonate cementation where present, does not meet the thickness or continuity or fracture requirements of a petrocalcic horizon.
Cementation: Weakly cemented to moderately cemented
Bedrock features: Fracture interval-10 to 25 cm (4 to 10 in) apart horizontally, kind-limestone, chalk or marl.
COMPETING SERIES:
Whitewright (TX) is a competing series in the same family. Similar soils are the
Doss (TX),
Keese (TX),
Quinlan (OK+KS), and
Spikebox (OK+TX).
Doss soils: Have a mollic epipedon.
Keese soils: Have a paralithic contact with weathered granite, granite grus, or gneiss of Precambrian
Era.
Quinlan soils: Has a shallow contact with densic sandstone bedrock.
Spikebox soils: Has a paralithic contact with sandstone bedrock
Whitewright soils: Are moist in the control section for longer periods.
GEOGRAPHIC SETTING:
Parent material: Residuum weathered from limestone bedrock of Cretaceous period, mainly from the Glen Rose and Comanche Peak formations. Also, interbedded marls and chalks occur on such formations as the Walnut and Keys Valley marls.
Landscape: Dissected Plateaus
Landform: Backslopes of ridges
Landform notes: Occurs on benched or stair-stepped topography consisting of risers and treads, also. The Brackett soils are mainly on the treads.
Slope: 1 to 60 percent, but is mostly 1 to 20 percent
Climate: Dry subhumid
Soil moisture: Typic ustic moisture regime
Precipitation Pattern: The majority of the yearly amount occurs during the fall and spring months. The winter and summer months are normally drier.
Mean annual air temperature: 18 to 21 degrees C (64 to 69 degrees F)
Mean annual precipitation: 610 to 864 mm (24 to 34 in)
Frost free days: 210 to 270 days
Elevation: 107 to 746 m (600 to 2,450 ft)
Thornthwaite annual P-E indices: 32 to 52
GEOGRAPHICALLY ASSOCIATED SOILS: These are
Cranfill (TX),
Denton (TX),
Doss (TX),
Eckrant (TX),
Karnes (TX),
Kerrville (TX),
Maloterre (TX),
Real (TX),
Tarrant (TX),
Topsey (TX) and
Valera (TX) series.
Cranfill, Denton, Doss, Karnes, Topsey, and Valera soils:
Occur lower on the landscape in footslope positions.
Eckrant, Maloterre, and Tarrant soils: Occur higher on the landscape in summit, shoulder, and backslope positions.
Kerrville and Real soils: Occur on similar position in the landscape.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate. Permeability in the petrocalcic horizon is slow to very slow. Runoff is very low on 1 to 3 percent slopes, low on 3 to 5 percent slopes, and medium on 5 to 20 percent slopes and high on 20 to 60 percent slopes.
USE AND VEGETATION: Mainly used as rangeland. The climax plant community is a tall grass savannah with motts of live oak and Texas oak scattered throughout the landscape. The dominant grass is little bluestem. Other grasses include yellow Indiangrass, sideoats grama, tall grama, seep muhly, slim tridens, hairy grama, silver bluestem, slim tridens, tall dropseed, and perennial threeawns. Woody plants include live oak, Texas oak, kidneywood and shin oak. Forbs, such as bundleflower, sensitive briar, Maximilian sunflower, Engelmann daisy, and gayfeather, are found throughout the site. With over grazing, the site could potentially deteriorate to a plant population of Ashe juniper, Texas persimmon, agarito, live oak, threeawns, Texas grama, hairy tridens, red grama, prairie coneflower, broomweed, and ragweed.
DISTRIBUTION AND EXTENT: West-Central Texas; Southwest Plateaus and Plains Range and Cotton Region, LLR I: MLRA 81B and 81C-Edwards Plateau, Central and Eastern parts; and. Southwestern Prairies Cotton and Forage Region, LRR J: MLRA 85-Grand Prairie;. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Kinney County, Texas (Reconnaissance Soil Survey of Southwest Texas); 1911.
REMARKS: Classification was changed 11/89 from Typic Ustochrepts to Udic Ustochrepts. On 10/2001 the type location was moved to Hays County, and the depth was changed from very deep to shallow and the subgroup changed back to Typic which was the original series concept.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: 0 to 15 cm (0 to 6 in) (A horizon)
Cambic horizon: 15 to 36 cm (6 to 14 in) (Bk horizon)
Paralithic contact: 36 cm (14 in) (top of Cr layer)
ADDITIONAL DATA: None
TAXONOMIC VERSION: Keys to Soil Taxonomy, 11th Edition, 2010.