LOCATION BRENNAN                 TX

Established Series
Rev. RRS-WJG-RM-CKH
11/2013

BRENNAN SERIES

The Brennan series consists of very deep, well drained soils. These nearly level to gently undulating soils formed in loamy eolian sands and calcareous loamy alluvium on vegetated sand sheet plains. Slope ranges from 0 to 5 percent. Mean annual air temperature is about 22 degrees C (72 degrees F) and mean annual precipitation is about 508 mm (20 in).

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, hyperthermic Aridic Haplustalfs

TYPICAL PEDON: Brennan fine sandy loam, on a south-southeast facing, 1 percent slope in rangeland; elevation is 168 meters (550 feet). (Colors are for dry soil unless otherwise stated.)

A--0 to 31 cm (0 to 12 in); brown (10YR 4/3) fine sandy loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; upper 2 inches is massive; hard, friable, slightly sticky and slightly plastic; common fine roots; neutral; gradual smooth boundary. (20 to 46 cm [8 to 18 in] thick)

Bt--31 to 66 cm (12 to 26 in); yellowish brown (10YR 5/4) sandy clay loam, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few fine roots; many fine pores; many root channels; few distinct clay films on surfaces of peds and in pores; slightly alkaline; diffuse smooth boundary. (10 to 76 cm [4 to 30 in] thick)

Bk--66 to 102 cm (26 to 40 in); light yellowish brown (10YR 6/4) sandy clay loam, yellowish brown (10YR 5/4) moist; weak fine and medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many fine roots; many fine pores; 2 percent fine threads and masses of calcium carbonate; violently effervescent; moderately alkaline; diffuse smooth boundary. (25 to 41 cm [10 to 16 in] thick)

BCk--102 to 203 cm (40 to 80 in); very pale brown (10YR 7/4) sandy clay loam, light yellowish brown (10YR 6/4) moist; weak fine and medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few fine pores; 10 percent fine masses and concretions of calcium carbonate; visible calcium carbonate decreases slightly with depth; violently effervescent; moderately alkaline.

TYPE LOCATION: Starr County, Texas; from the intersection of U.S. Highway 83 and Farm Road 755 in Rio Grande City; 19.2 miles northeast on Farm Road 755 to Farm Road 2294; 5.75 miles northeast on Farm Road 2294 to Farm Road 2894; 1.6 miles south on Farm Road 2894; and 200 feet west of road in pastureland. Rincon, Texas USGS topographic quadrangle. Latitude: 26 degrees, 35 minutes, 35 seconds N; Longitude: 98 degrees, 32 minutes, 23 second, W.; NAD 83.

RANGE IN CHARACTERISTICS:

Soil Moisture: An aridic ustic moisture regime. The soil moisture control section is moist in some or all parts for less than 90 consecutive days in normal years.
Mean annual soil temperature: 21 to 24 degrees C (70 to 76 degrees F)
Depth to argillic horizon: 20 to 46 cm (8 to 18 in)
Depth to secondary calcium carbonate: 25 to 91 cm (10 to 36 in)
Depth to calcic horizon: 102 to 152 cm (40 to 60 in)

Particle-size control section (weighted average)
Clay content: 18 to 30 percent
Coarse Fragments: 0 to 10 percent
CEC/clay ratio: 0.60 to 0.75

A horizon
Hue: 7.5YR or 10YR
Value: 4 or 5
Chroma: 2 or 4. The soil has colors and organic carbon that meet requirements for a mollic epipedon, but the surface is both massive and hard when dry.
Texture: fine sandy loam
Clay content: 8 to 18 percent
Electrical conductivity (dS/m): 0 to 2
Sodium adsorption ratio: 0 to 1
Reaction: neutral or slightly alkaline

Bt Horizon
Hue: 7.5YR or 10YR
Value: 4 to 6
Chroma: 2 to 4
Texture: sandy clay loam, loam, fine sandy loam
Clay content: 18 to 30 percent
Clay films: few or common, faint or distinct, on surfaces of peds and lining pores
Coarse fragments: 0 to 10 percent, non-flat, rounded, indurated quartz
Identifiable secondary carbonate: 0 to 2 percent, very fine and fine, films, threads and masses, on surfaces of peds
Calcium carbonate equivalent: 0 to 5 percent
Gypsum: 0 to 2 percent
Electrical conductivity (dS/m): 0 to 4
Sodium adsorption ratio: 0 to 1
Reaction: slightly alkaline or moderately alkaline

Bk Horizon: (and Btk where present)
Hue: 7.5YR or 10YR
Value: 5 to 7
Chroma: 2 to 4
Texture: sandy clay loam, loam, fine sandy loam, or clay loam
Clay content: 18 to 30 percent
Coarse fragments: 0 to 10 percent, non-flat, rounded, indurated quartz
Identifiable secondary carbonate: 2 to 20 percent, fine or medium, on surfaces of peds, occurring in the form of concretions, masses, films, threads, and weakly cemented nodules
Calcium carbonate equivalent: 9 to 40 percent
Gypsum: 0 to 2 percent
Electrical conductivity (dS/m): 1 to 4
Sodium adsorption ratio: 0 to 1
Reaction: slightly alkaline or moderately alkaline

BCk Horizon:
Hue: 7.5YR or 10YR
Value: 5 to 7
Chroma: 2 to 4
Texture: sandy clay loam, loam, or fine sandy loam
Clay content: 15 to 25 percent
Coarse fragments: 0 to 10, non-flat, rounded, indurated quartz
Identifiable secondary carbonate: 2 to 20 percent; fine or medium; films on surfaces of peds, concretions, masses, threads, and weakly cemented nodules
Calcium carbonate equivalent: 10 to 40 percent
Gypsum: 0 to 2 percent
Electrical conductivity (dS/m): 1 to 4
Sodium adsorption ratio: 0 to 2
Reaction: slightly alkaline or moderately alkaline

COMPETING SERIES: There are no competing series in the same family. Similar soils are the Aguilares (TX), Brundage (TX), Duval (TX), Hebbronville (TX), Verick (TX), and Willacy (TX) series.
Aguilares soils: do not have an argillic horizon.
Brundage soils: have a natric horizon.
Duval soils: have siliceous mineralogy.
Hebbronville soils: are coarse-loamy in the particle-size control section.
Verick soils: are shallow to a paralithic contact with sandstone.
Willacy soils: have a mollic epipedon and are moist in the soil moisture control section for longer periods of time

GEOGRAPHIC SETTING:
Parent material: loamy eolian sands and calcareous loamy alluvium
Landscape: Inland, dissected coastal plain
Landform: convex treads of vegetated sand sheet plains
Slope: 0 to 5 percent
Mean annual precipitation: 483 to 711 mm (19 to 28 in)
Precipitation pattern: June to August and December to February are the driest months, while September to November and March to May are the wettest months.
Mean annual air temperature: 21.1 to 23.9 degrees C (70 to 75 degrees F)
Frost-free period: 260 to 340 days
Elevation: 21.3 to 182.9 m (70 to 600 ft)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Copita (TX), Delmita (TX), Hebbronville (TX), Hidalgo (TX), McAllen (TX), Ramadero (TX), Tela (TX), Willacy (TX), and Zapata (TX) series.
Copita soils: are 51 to 102 cm (20 to 40 in) to a paralithic contact, are calcareous throughout, and occur on similar to slightly higher positions.
Delmita soils: are 51 to 102 cm (20 to 40 in) to a petrocalcic horizon and have 7.5YR colors or redder throughout.
Hebbronville soils: occur on similar to slightly higher positions.
Hidalgo and McAllen soils: do not have an argillic horizon, are calcareous throughout, and occur on similar positions.
Ramadero, Tela and Willacy soils: have a mollic epipedon and occur on lower positions.
Zapata soils: are 25 to 51 cm (10 to 20 in) to a petrocalcic horizon and occur on slightly higher positions.

DRAINAGE AND PERMEABILITY: Well drained. Moderate permeability. Runoff is negligible on slopes less than 1 percent; low on 1 to 5 percent slopes.

USE AND VEGETATION: Used mostly as livestock grazing and wildlife habitat. A few areas are farmed. When irrigated, soils are suited to a wide variety of crops. Native vegetation is twoflower trichloris, Arizona cottontop, plains bristlegrass, hooded windmillgrass, pink pappusgrass and woody species consisting of mesquite, Texas ebony, spiny hackberry, guayacan, lote, and pricklypear.

DISTRIBUTION AND EXTENT: Western and Central Rio Grande Plain and Sandsheet Prairie, Texas; LRR I; MLRA 83B, 83C, and 83E; the series has large extent.

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

SERIES ESTABLISHED: Webb County, 1906, Laredo area.

REMARKS: These soils have been mapped on plains in the Lower Rio Grande Valley, vegetated plains in the Sandsheet Prairie as well as stream terraces in the Western Rio Grande Plain.

Edited 11/2013 (RFG-CKH): added BCk to RIC; updated the Competing series, Geographic setting, and Associated series sections.

Diagnostic horizons and features recognized in this pedon are:
Particle size control section: 31 to 81 cm (12 to 32 in) (Bt horizon)
Ochric epipedon: 0 to 31 cm (0 to 12 in) (A horizons)
Argillic horizon: 31 to 66 cm (12 to 26 in) (Bt horizon)
Calcic horizon: 102 to 203 cm (40 to 80 in) (BCk horizon)

ADDITIONAL DATA: NSSL data number S01TX-505-001 from Zapata County, Texas. The assignment of the cation-exchange activity class is supported by laboratory data number 84TX215001 from Hidalgo County, Texas.

Taxanomic version: Keys to Soil Taxonomy, Eleventh Edition, 2010.

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National Cooperative Soil Survey
U.S.A.