LOCATION RANDADO                 TX

Established Series
Rev. HCD-RRS-CLG
11/2016

RANDADO SERIES

The Randado series consists of soils that are very shallow and shallow to a petrocalcic horizon. They are well drained, moderately permeable soils that formed in noncalcareous loamy alluvium over calcareous loamy residuum. These nearly level to gently sloping soils are on broad, low ridges on inland, dissected coastal plains. Slope ranges from 0 to 5 percent. Mean annual temperature is about 23 degrees C (73 degrees F) and annual precipitation is about 584 mm (23 in).

TAXONOMIC CLASS: Loamy, mixed, active, hyperthermic, shallow Petrocalcic Paleustalfs

TYPICAL PEDON: Randado fine sandy loam in rangeland.
(Colors are for dry soil unless otherwise stated.)

A1--0 to 5 cm (0 to 2 in); reddish brown (5YR 5/4) fine sandy loam, dark reddish brown (5YR 3/4) moist; weak fine granular structure; hard, very friable, slightly sticky and nonplastic; porous beneath the thin surface crust; few angular petrocalcic fragments; few rounded chert pebbles; slightly acid; clear smooth boundary. Thickness is 2 to 20 cm (1 to 8 in)

A2--5 to 20 cm (2 to 8 in); reddish brown (5YR 4/4) fine sandy loam, dark reddish brown (5YR 3/4) moist; weak fine granular structure; hard, very friable; slightly sticky and nonplastic; many fine pores; few angular petrocalcic fragments; few rounded chert pebbles; slightly acid; clear wavy boundary. Combined thickness of the A horizon is 10 to 38 cm (4 to 15 in)

Bt--20 to 41 cm (8 to 16 in); yellowish red (5YR 4/6) fine sandy loam, yellowish red (5YR 4/6) moist; weak medium prismatic structure parting to weak fine subangular blocky; hard, friable, slightly sticky and nonplastic; many fine pores; few root channels; few clay bridges and few faint clay films in pores and lining root channels; neutral; abrupt wavy boundary. Thickness is 8 to 31 cm (3 to 12 in)

Bkkm1--41 to 51 cm (16 to 20 in); pinkish white (5YR 8/2) strongly cemented calcium carbonate; weak platy to fractured in upper 5 to 8 cm (2 to 3 in), massive below; upper surface has laminar cap; moderately alkaline; gradual wavy boundary. Thickness is 8 to 127 cm (3 to 50 in)

Bkkm2--51 to 203 cm (20 to 80 in); white (10YR 8/1) weakly cemented calcium carbonate; massive but contains a few fractures; moderately alkaline.

TYPE LOCATION: Jim Hogg County, Texas; from the intersection of Texas Highways 16 and 285 in Hebbronville, 3 miles south on Texas Highway 16 to Farm Road 3073, 16 west on Farm Road 3073 to Farm Road 649, 0.2 miles south on Farm Road 649, 200 feet east in rangeland.
USGS topographic quadrangle: Thompsonville, TX
Latitude: 27 degrees, 14 minutes, 04 seconds N.;
Longitude: 98 degrees, 55 minutes, 58 seconds W.;
Datum: NAD 83.

RANGE IN CHARACTERISTICS:
Soil Moisture: Ustic moisture regime bordering on aridic. The soil moisture control section is dry in some or all parts for more than 220 days, cumulative, in normal years.
Mean annual soil temperature: 21.7 to 23.3 degrees C (71 to 74 degrees F).
Depth to argillic horizon: 10 to 38 cm (4 to 15 in)
Depth to petrocalcic horizon: 20 to 51 cm (8 to 20 in)

A Horizon
Hue: 2.5YR, 5YR, or 7.5YR
Value: 4 to 6
Chroma: 4 to 6
Texture: loamy fine sand or fine sandy loam
Clay content: 8 to 18 percent
Coarse fragments: 0 to 15 percent total; 0 to 5 percent angular calcrete and/or petrocalcic fragments, 0 to 15 percent rounded chert gravel
Pararock fragments: 0 to 2 percent
Base saturation: 75 to 90 percent
Calcium carbonate equivalent: 0 to 2 percent
Electrical Conductivity (dS/m): 0 to 1
Gypsum: 0 to 1 percent
Reaction (pH): slightly acid to slightly alkaline (6.1-7.8)

Bt Horizon
Hue: 2.5YR, 5YR, or 7.5YR
Value: 3 to 6
Chroma: 4 to 6
Texture: fine sandy loam or sandy clay loam and gravelly counterparts
Clay content: 15 to 27 percent
Coarse fragments: 0 to 25 percent total; 0 to 25 percent rounded chert gravel, 0 to 15 percent angular calcrete and/or petrocalcic fragments.
Pararock fragments: 0 to 5 percent
Base saturation: 80 to 95 percent
Calcium carbonate equivalent: 0 to 2 percent
Electrical Conductivity (dS/m): 0 to 1
Gypsum: 0 to 1 percent
Reaction (pH): slightly acid to slightly alkaline (6.1-7.8)

Bkkm1 Horizon
Hue: 5YR, 7.5YR, or 10YR
Value: 7 or 8
Chroma: 2 or 3
Base saturation: 100 percent
Calcium carbonate equivalent: 50 to 90 percent
Reaction (pH): moderately alkaline (7.9-8.4)

Bkkm2 Horizon
Hue: 7.5YR or 10YR
Value: 7 or 8
Chroma: 2 or 3
Texture: Apparent field - fine sandy loam or loam
Coarse fragments: 0 to 5 percent rounded chert pebbles and cobbles
Pararock fragments: 0 to 5 percent
Base saturation: 100 percent
Calcium carbonate equivalent: 60 to 90 percent
Electrical Conductivity (dS/m): 0 to 1
Gypsum: 0 to 1 percent
Reaction (pH): moderately alkaline (7.9-8.4)

COMPETING SERIES: This is the Lacoste series in the same family. Similar soils are the Cuevitas, Delmita, Jimenez, Quemado, Sharvana, and Zapata series.
Lacoste soils: are moist in the soil moisture control section for 90 or more consecutive days in normal years (typic ustic)
Cuevitas and Zapata soils: do not have an argillic horizon.
Delmita soils: are moderately deep to the petrocalcic horizon.
Jimenez and Quemado soils: have a loamy-skeletal particle-size control section and in addition Jimenez soils have a mollic epipedon.
Sharvana soils: are dry in the soil moisture control section for more than half the time during the growing season and are in a thermic soil temperature regime.

GEOGRAPHIC SETTING:
Parent material: noncalcareous loamy alluvium that has been partially reworked by wind over calcareous loamy residuum and petrocalcics of the Goliad Formation.
Landscape: inland, dissected coastal plains
Landform: summits and shoulders of broad, low ridges.
Slope: 0 to 5 percent
Precipitation pattern: The soil is driest during the months of June through August and December through February. These soils are intermittently moist in September through November and March through May.
Mean annual precipitation: 508 to 635 (20 to 25 in)
Thornthwaite annual P-E indices: 21 to 34
Mean annual temperature: 21.1 to 23.3 degrees C (70 to 74 degrees F)
Frost-free period: 265 to 340 days
Elevation: 30.5 to 289.6 m (100 to 950 ft)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cuevitas, Delmita, and Zapata series.
Cuevitas and Delmita soils: occur on similar positions.
Zapata soils: occur on similar to slightly higher positions, but with steeper surface gradients.

DRAINAGE AND PERMEABILITY: Well drained. Moderate permeability above a very slowly to slowly permeable petrocalcic horizon. Runoff is moderate to high on slopes less than 1 percent and high to very high on 1 to 5 percent slopes.

USE AND VEGETATION: Used primarily for rangeland and wildlife habitat. Grass species are plains bristlegrass, Texas bristelgrass, hooded windmillgrass, tanglehead, Wright's threeawn, red grama, hairy tridens, gummy lovegrass, and whorled dropseed. Brush species include leatherstem, guajillo, kindneywood, and range ratany.

DISTRIBUTION AND EXTENT: Central Rio Grande Plain, Texas; LRR I; MLRA 83C; the series is of large extent.

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

SERIES ESTABLISHED: Jim Hogg County, Texas, 1970.

REMARKS: Classification change from Petrocalcic Ustic Paleargids to Petrocalcic Paleustalfs based on geographic distribution of the soil, analysis of rainfall patterns, range species composition and production.

Edited 11/2016 (RFG-GWH): Updated competing series, geographic setting, and associated soils sections.

Diagnostic horizons and features recognized in this pedon are:
Particle size control section: 20 to 41 cm (8 to 16 in) (Bt horizon).
Ochric epipedon: 0 to 20 cm (0 to 8 in) (A horizons).
Argillic horizon: 20 to 41 cm (8 to 16 in) (Bt horizon).
Petrocalcic horizon: 41 to 203 cm (16 to 80 in) (Bkkm horizon).

ADDITIONAL DATA: The assignment of the cation-exchange activity class is inferred from laboratory data from similar soils in the geographic area.

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

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National Cooperative Soil Survey
U.S.A.