LOCATION PADRONES TXEstablished Series
TAXONOMIC CLASS: Loamy, mixed, active, hyperthermic Arenic Natrustalfs
TYPICAL PEDON: Padrones fine sand--in nearly level rangeland at an elevation of 9 m (73 ft). (Colors are for dry soil unless otherwise stated.)
A--0 to 43 cm (0 to 17 in); pale brown (10YR 6/3) fine sand, brown (10YR 4/3) moist; single grained; loose, very friable; common fine and very fine roots; neutral; clear smooth boundary. (thickness of the A horizon is 31 to 86 cm [12 to 34 in])
E--43 to 71 cm (17 to 28 in); very pale brown (10YR 7/3) fine sand, pale brown (10YR 6/3) moist; single grained; loose, very friable, few fine and very fine roots; few krotovina; neutral; abrupt smooth boundary. (thickness of the E horizon is 15 to 41 cm [6 to 16 in])
2Btn1--71 to 76 cm (28 to 30 in); light brownish gray (10YR 6/2) loamy fine sand, grayish brown (10YR 5/2) moist; common fine distinct brownish yellow (10YR 6/8) and few fine distinct strong brown (7.5YR 5/6) masses of redox concentrations; moderate coarse prismatic structure parting to moderate medium blocky; very hard, firm; few fine and very fine roots; few faint clay films, clean sand grains and organic coatings on surfaces of prisms; few fine black concentrations; neutral; clear smooth boundary.
2Btn2--76 to 86 cm (30 to 34 in); light brownish gray (10YR 6/2) fine sandy loam, grayish brown (10YR 5/2) moist; few fine and medium distinct brownish yellow (10YR 6/8) masses of redox concentrations; strong coarse prismatic structure parting to moderate medium blocky; extremely hard, very firm; few fine and very fine roots; few faint clay films on faces of peds, clean sand grains on prism surfaces; organic coatings on faces of peds; few fine black concentrations; slightly alkaline; clear smooth boundary.
2Btn3--86 to 102 cm (34 to 40 in); light gray (10YR 7/2) fine sandy loam, light brownish gray (10YR 6/2) moist; many medium distinct yellow (10YR 7/8) and few fine prominent red (2.5YR 5/6) masses of redox concentrations; moderate coarse prismatic structure parting to moderate medium blocky; very hard, firm; few very fine roots; few faint clay films on faces of peds; few fine black concentrations; slightly alkaline; gradual smooth boundary.
2Btn4--102 to 150 cm (40 to 59 in); pale yellow (2.5Y 8/2) fine sandy loam, light gray (2.5Y 7/2) moist; common fine distinct yellow (10YR 8/8) and few fine prominent red (2.5YR 5/6) masses of redox concentrations; weak coarse prismatic structure parting to moderate medium blocky; very hard, firm; few faint clay films on faces of peds; few fine black concentrations; few white spots about 1 cm in diameter assumed to be salts moderately alkaline; gradual smooth boundary. (combined thickness of the 2Btn horizons is 76 to 152 cm [30 to 60 in])
2Btn5--150 to 203 cm (59 to 80 in); pale yellow (2.5Y 8/2) fine sandy loam, light gray (2.5Y 7/2) moist; few fine distinct yellow (10YR 7/6) masses of redox concentrations; weak moderate subangular blocky structure; very hard, firm; few faint clay films on faces of peds; few fine black concentrations; few white spots about 1 cm in diameter assumed to be salts; few calcium carbonate nodules up to 3.5 cm in diameter; strongly alkaline.
TYPE LOCATION: Brooks County, Texas; from post office in Encino; 0.6 mile north on U.S. 281 to gate of the Encino Division of the King Ranch; 5.7 miles east on ranch road; 5.0 miles south on ranch road; 55 feet west in rangeland. San Tomas Camp, Texas USGS topographic quadrangle. Latitude: 26 degrees, 52 minutes, 41 seconds North; Longitude: 98 degrees, 03 minutes, 27 seconds West; NAD 83.
RANGE IN CHARACTERISTICS:
Soil Moisture: An ustic soil moisture regime. Precipitation pattern: moist spring and fall months and dry summer and winter months. The soil moisture control section is dry in some or all parts for more than 90 but less than 180 cumulative days in normal years. June through August and December through February are the driest months. These soils are intermittently moist in September through November and March through May.
A horizon
Hue: 10YR
Value: 4 to 6
Chroma: 3 or 4
Texture: fine sand or loamy fine sand
Reaction: moderately acid to neutral
E horizon
Hue: 10YR
Value: 6 to 8
Chroma: 3 or 4
Texture: fine sand or loamy fine sand
Reaction: moderately acid to neutral
2Btn horizon
Hue: 10YR or 2.5Y
Value: 5 to 8
Chroma: 2 or 4
Texture: loamy fine sand, fine sandy loam, or sandy clay loam
Clay content: 8 to 24 percent in the upper 51 cm (20 in)
Redox concentration: size-fine or medium, amount-few or common, contrast-distinct or prominent, boundaries-sharp
ESP: more than 38 within upper 41 cm (16 in)
One or more lithologic discontinuities, related to sand and silt ratios, occur in the Bt horizon.
Reaction: neutral to strongly alkaline
EC (dS/cm): 0 to 3
SAR: 13 to 30
COMPETING SERIES: There are no competing series in the same family. Similar soils are
Nueces (TX),
Palobia (TX),
Quiteria (TX),
Ramita (TX),
Sarita (TX),
Sauz (TX), and
Willamar (TX) series.
Nueces soils: do not have a natric horizon.
Palobia, Quiteria, Ramita, Sauz, and Willamar soils: have surface epipedon less than 51 cm (20 in) thick.
Sarita soils: have sandy surfaces more that 102 cm (40 in) thick and do not have a natric horizon.
GEOGRAPHIC SETTING:
Parent material: sandy eolian deposits over loamy alluvium of Pleistocene age
Landform: vegetated sandsheet prairie
Slope: 0 to 3 percent
Mean annual air temperature: 22 to 23 degrees C (72 to 74 degrees F)
Mean annual precipitation: 610 to 711 mm (24 to 28 in)
Frost-free period: 300 to 341 days
Elevation: 9 to 82 m (30 to 272 ft)
Thornthwaite P-E Index: 28 to 44
GEOGRAPHICALLY ASSOCIATED SOILS: These include the
Bordas,
Nueces,
Palobia,
Quiteria,
Ramita,
Sarita, and
Sauz series.
Bordas soils: are in depressions and do not have a natric horizon.
Nueces and Sarita soils: are on similar to slightly higher positions and do not have natric horizons.
Palobia, Quiteria, Ramita, and Sauz soils: have a surface epipedon less than 51 cm (20 in) thick and are lower positions.
DRAINAGE AND PERMEABILITY: Moderately well drained, runoff is low on slopes less than 1 percent and medium on 1 to 3 percent slopes. Water movement through the soil is moderately slow. During normal years of precipitation, a seasonal water table perches on top of the natric horizon for brief periods of less than 1 to 2 weeks, most in the months of May to October. In some years tropical storms or prolonged periods of above-normal precipitation result in a seasonal water table perched on top of the natric horizon for 2 to 4 weeks most usually in the months of June to October.
USE AND VEGETATION: Used primarily for livestock grazing and wildlife habitat. The climax native vegetation in excellent condition is composed of 90 percent grasses, 5 percent woody plants, and 5 percent forbs. In excellent condition, tall and mid grasses such as seacoast bluestem, brownseed paspalum and switchgrass dominate. Major forbs include snoutbean, arrowleaf, sida, prairie coneflower, firewheel, phlox, and ragweed. Mesquite is the dominant woody plant. The ecological site is Sandy, (R083EY706TX).
DISTRIBUTION AND EXTENT: Sandsheet Prairie (MLRA 83E in LRR I) of southern Texas. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Brooks County, Texas, 1983.
REMARKS: Padrones soils were formerly included with the Nueces series. Particle-size distribution analyses, sand/silt ratios and clay free size fractions indicate that a lithologic discontinuity occurs at the upper boundary of the natric horizon. In 2005 this series was reclassified from Aquic Arenic Natrustalfs to Arenic Natrustalfs based on the 1989 to 2002 water table study* conducted on similar upland soils in the central part of the Texas Gulf Coast Prairie MLRA. This soil does not have aquic conditions in most years. In some years, reduced conditions develop just above and in the upper part of the natric horizon for brief periods following extreme above-normal precipitation events. Redoximorphic features that result from these above-normal events are not diagnostic for classification.
*partial data in Proceedings of eighth international soil correlation meeting (VIII ISCOM) 1992, USDA-SCS National Soil Survey Center, Lincoln, NE
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: 0 to 43 cm (0 to 17 in)
Arenic feature: 0 to 71 cm (0 to 28 in)
Natric horizon: 71 to 203 cm (28 to 80 in)
Lithologic discontinuity: 71 cm (28 in)
ADDITIONAL DATA: National Soil Survey Laboratory data from Brooks County, Texas (S77TX-047-003) Lab No. (78P1049-1061).
TAXONOMIC VERSION: Keys to Soil Taxonomy, Tenth Edition, 2006.