LOCATION POINT ISABEL            TX

Established Series
JLS-JKW-RM
03/2016

POINT ISABEL SERIES

The Point Isabel series consists of very deep, well drained, slowly permeable soils that formed in calcareous loamy and clayey eolian deposits. These soils are on vegetated dunes. Slope ranges from 1 to 5 percent. Mean annual air temperature is about 23 degrees C (73.5 degrees F) and mean annual precipitation is about 686 mm (27 in).

TAXONOMIC CLASS: Fine, mixed, active, hyperthermic Typic Calciustepts

TYPICAL PEDON: Point Isabel clay loam--in rangeland. (Colors are for dry soil unless otherwise stated.)

A1--0 to 20 cm (0 to 8 in); light brownish gray (10YR 6/2) clay loam, dark grayish brown (10YR 4/2) moist; weak, fine granular and subangular blocky structure; slightly hard, friable; strongly effervescent; moderately alkaline; clear smooth boundary. (10 to 20 cm [4 to 8 in] thick)

A2--20 to 30 cm (8 to 12 in); dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; hard, firm; strongly effervescent; moderately alkaline; clear wavy boundary. (8 to 38 cm [3 to 15 in] thick)

Bkn1--30 to 48 cm (12 to 19 in); light brownish gray (10YR 6/2) clay, grayish brown (10YR 5/2) moist; moderate coarse prismatic structure parting to moderate fine and medium angular blocky; hard, firm; common films and threads of calcium carbonate; strongly effervescent; moderately alkaline, abrupt wavy boundary.

Bkn2--48 to 56 cm (19 to 22 in); grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate coarse prismatic structure parting to moderate fine angular blocky; hard, firm; common films and threads of calcium carbonate; strongly effervescent; moderately alkaline; abrupt wavy boundary.

Bkn3--56 to 94 cm (22 to 37 in); light brownish gray (10YR 6/2) clay, grayish brown (10YR 5/2) moist; moderate fine and medium angular blocky structure; hard, firm; few films and threads of calcium carbonate; strongly effervescent; moderately alkaline; abrupt wavy boundary. (Combined thickness of the Bkn horizons is 26 to 100 cm [10 to 40 in].)

Bknb1--94 to 107 cm (37 to 42 in); gray (10YR 5/1) clay, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; hard, firm; few threads of calcium carbonate; strongly effervescent; moderately alkaline; clear wavy boundary. (Combined thickness of the Bknb horizons is 38 to 147 cm [15 to 58 in].)

Bknb2--107 to 203 cm (42 to 80 in); light gray (10YR 7/2) clay, grayish brown (10YR 5/2) moist; moderate fine and medium angular blocky structure; hard, firm; common threads and films of calcium carbonate; strongly effervescent; moderately alkaline.

TYPE LOCATION: Cameron County, Texas; from the intersection of Texas Highway 4 and Farm Road 511, which is about 0.5 mile northeast of Brownsville International Airport; 7.6 miles east on Texas Highway 4; 0.2 mile north on field road; 250 ft west in rangeland.

RANGE IN CHARACTERISTICS:
Soil Moisture: An ustic soil moisture regime.
Depth to secondary calcium carbonate: 10 to 41 cm (4 to 16 in)
Depth to calcic horizon: 10 to 41 cm (4 to 16 in)
Depth to buried horizons: 46 to 127 cm (18 to 50 in)

A1 horizon:
Hue: 10YR
Value: 4 to 6
Chroma: 2 or 3
Texture: clay loam, silty clay loam, or clay
Clay content: 35 to 50
Electrical Conductivity (dS/m): 4 to 8
Sodium Adsorption Ratio: 11 to 62
Effervescence: slightly or strongly
Reaction: moderately alkaline or strongly alkaline

A2 horizon:
Hue: 10YR
Value: 4 to 6
Chroma: 2 or 3
Texture: clay loam, silty clay loam, or clay
Clay content: 35 to 55
Electrical Conductivity (dS/m): 4 to 8
Sodium Adsorption Ratio: 11 to 62
Effervescence: slightly or strongly
Reaction: moderately alkaline or strongly alkaline

Bkn horizon:
Hue: 10YR
Value: 5 or 6
Chroma: 2
Texture: clay loam, silty clay loam or clay
Clay content: 35 to 55
Identifiable secondary carbonate: 2 to 10 percent, fine and medium, films, threads, and filaments in matrix
Identifiable salts: 2 to 7 percent, fine masses, in matrix
Electrical Conductivity (dS/m): 4 to 40
Sodium Adsorption Ratio: 72 to 95
Effervescence: slight to violent
Reaction: moderately alkaline or strongly alkaline

Bknb horizon:
Hue: 10YR or 2.5Y
Value: 4 or 6
Chroma: 2
Texture: clay
Clay content: 45 to 55
Identifiable secondary carbonate: 2 to 10 percent, fine and medium, films, threads, and filaments in matrix
Identifiable salts: 2 to 7 percent, fine masses, in matrix
Electrical Conductivity (dS/m): 4 to 40
Sodium Adsorption Ratio: 72 to 95
Effervescence: slight to violent
Reaction: moderately alkaline or strongly alkaline

COMPETING SERIES: There are no series in the same family. Similar soils include the Copita, Garceno, Lalinda, Latina, Maverick, and Sejita series.
Copita and Lalinda soils: have less than 35 percent clay in the particle-size control section.
Garceno and Maverick soils: are dry in the moisture control section for longer period; Maverick soils have sola less than 100 cm (40 in) in thickness.
Latina and Sejita soils: have a salic horizon and have seasonal water tables within 76 cm (30 in) of the surface.

GEOGRAPHIC SETTING:
Parent Material: Holocene age clayey eolian deposits derived from sedimentary rock
Landscape: low coastal plains
Landform: clay dunes
Slope: 1 to 5 percent
Mean annual temperature: 22.2 to 23.9 degrees C (72 to 75 degrees F)
Mean annual precipitation: 635 to 752 mm (25 to 30 in)
Frost-free period: 300 to 350 days
Elevation: 1 to 9 m (3 to 29.5 ft)
Thornthwaite annual P-E indices: 31 to 44

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Barrada, Lomalta, and Sejita series.
Barrada soils: are on linear plains and saturated for periods of 4 to 6 months during most years.
Lomalta soils: are on linear coastal terraces are poorly drained Vertisols.
Sejita soils: are on linear coastal terraces and remain saturated for more than one month in normal years.

DRAINAGE AND PERMEABILITY: Well drained. Permeability is slow. Runoff is very high. These soils are flooded rarely for very brief to brief periods during tropical storms.

USE AND VEGETATION: Used for livestock grazing or wildlife habitat. These soils are unsuitable for crop production. Vegetation consists of a sparse stand of stunted mesquite, spiny hackberry, leatherstem, prickypear, lovegrass tridens, Texas bristlegrass, hooded windmill, and various salt-tolerant species. The ecological site is Coastal Ridge, PE 31-44, R150BY647TX.

DISTRIBUTION AND EXTENT: Gulf Coast Saline Prairies (MLRA 150B in LRR T) in the lower coastal plain of southern Texas. The series is of moderate extent.

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

SERIES ESTABLISHED: Cameron County, Texas; 1907.

REMARKS: Classification changed from Ustollic Camborthids to Typic Calciustepts 11/2000 based on typifying pedon description. Further study and characterization data of the series is needed to verify classification.
Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon: 0 to 30 cm (0 to 12 in) (A horizon)
Calcic horizon: 30 to 56 cm (12 to 22 in) (Bkn1 and Bkn2 horizons)
Buried horizons: 94 to 203 cm (37 to 80 in) (Bknb1 and Bknb2 horizons)

ADDITIONAL DATA: none

Taxonomic Version: Keys to Soil Taxonomy, Twelfth Edition, 2014

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National Cooperative Soil Survey
U.S.A.