LOCATION MONWEBB                 TX

Established Series
PDH-CKH
02/2018

MONWEBB SERIES

The Monwebb series consists of very deep, moderately well drained, very slowly permeable soils that formed in saline, clayey alluvium derived from the tertiary aged sediments. These nearly level to very gently sloping, occasionally flooded soils are on floodplains. Slope ranges from 0 to 2 percent. Mean annual temperature is about 22 degrees (72 degrees F) and mean annual precipitation is about 584 mm (23 in).

TAXONOMIC CLASS: Fine, smectitic, hyperthermic Sodic Haplusterts

TYPICAL PEDON: Monwebb clay, on a 0.5 percent concave west-facing slope in rangeland; elevation is 96 meters (315 feet). (Colors are for dry soil unless otherwise stated.)

A1--0 to 13 cm (0 to 5 in); dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; very hard, very firm, very sticky and very plastic; many fine and medium roots, few coarse roots; few very fine tubular pores; SAR is 2; 1 percent rounded siliceous gravels; strongly effervescent; moderately alkaline; clear wavy boundary.

A2--13 to 28 cm (5 to 11 in); dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; moderate medium angular blocky structure parting to weak fine and medium granular; extremely hard, very firm, very sticky and very plastic; common fine and few medium roots; few very fine tubular pores; 5 percent distinct pressure faces; 1 percent rounded siliceous gravels; Sodium Adsorption Ratio is 8; strongly effervescent; moderately alkaline; clear wavy boundary. (combined thickess of the A horizon is 18 to 61 cm [7 to 24 in])

Bnss--28 to 71 cm (11 to 28 in); dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; moderate fine and medium angular blocky structure; extremely hard, very firm, very sticky and very plastic; common very fine and fine roots, few coarse roots; few very fine tubular pores; 10 percent distinct pressure faces; few fine distinct yellowish brown (10YR 5/4) masses of oxidized iron along root channels; 1 percent rounded siliceous gravels; 1 percent fine masses of salt; Sodium Adsorption Ratio is 22; strongly effervescent; slightly alkaline; clear wavy boundary. (15 to 71 cm [6 to 28 in] thick)

Bnssz--71 to 99 cm (28 to 39 in); dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; moderate fine and medium prismatic structure parting to moderate fine and medium angular blocky; extremely hard, very firm, very sticky and very plastic; common very fine and fine roots; few very fine pores; common fine pressure faces; few coarse distinct masses of yellowish brown (10YR 5/4) masses of oxidized iron; 1 percent snail shell fragments; 1 percent rounded siliceous gravels; 3 percent fine threads and 1 percent very fine salt crystals; Sodium Adsorption Ratio is 23; strongly effervescent; slightly alkaline; gradual wavy boundary. (15 to 38 cm [6 to 15 in] thick)

Bknssz--99 to 117 cm (39 to 46 in); grayish brown (10YR 5/2) clay, dark grayish brown (10YR 4/2) moist; moderate medium and coarse prismatic structure parting to moderate medium angular blocky; extremely hard, very firm, very sticky and very plastic; few very fine roots; few very fine tubular pores; 1 percent medium and coarse calcium carbonate masses; 1 percent faint dark grayish brown (10YR 4/2) moist, organic stains; few fine pressure faces; 1 percent rounded siliceous gravels; 2 percent fine masses and 1 percent fine threads of salts; Sodium Adsorption Ratio is 25; strongly effervescent; slightly alkaline; gradual wavy boundary. (15 to 61 cm [6 to 24 in] thick)

Bknz1--117 to 150 cm (46 to 59 in); 70 percent pale brown (10YR 6/3), 20 percent grayish brown (10YR 5/2) and 10 percent light gray (10YR 7/2) clay, brown (10YR 5/3), dark grayish brown (10YR 4/2) and light brownish gray (10YR 6/2) moist; weak medium and coarse prismatic structure parting to moderate medium angular blocky; very hard, very firm, very sticky and very plastic; few very fine roots; few very fine tubular pores; few fine faint masses of yellowish brown (10YR 5/4) redox concentrations, few medium distinct masses of light gray (10YR 7/1) iron depletions, few very fine iron-manganese masses; 3 percent medium and coarse calcium carbonate masses; 2 percent fine masses and threads of salts; Sodium Adsorption Ratio is 27; 1 percent rounded siliceous gravels; strongly effervescent; slightly alkaline; diffuse wavy boundary.

Bknz2--150 to 196 cm (59 to 77 in); 60 percent light gray (10YR 7/2) and 40 percent very pale brown (10YR 7/3) clay loam, light brownish gray (10YR 6/2) and pale brown (10YR 6/3) moist; weak medium and coarse prismatic structure parting to moderate medium angular blocky; very hard, very firm, very sticky and very plastic; common very fine tubular pores; few very fine iron-manganese masses; few fine distinct masses of yellowish brown (10YR 5/4) masses of oxidized iron with diffuse boundaries; 1 percent very fine masses of calcium carbonate; 1 percent rounded siliceous gravels; 2 percent fine masses and threads of salts; Sodium Adsorption Ratio is 31; strongly effervescent; moderately alkaline; diffuse wavy boundary. (combined thickness of the Bknz horizons is 53 to 165 cm [21 to 65 in])

Bknz3--196 to 203 cm (77 to 80 in); very pale brown (10YR 7/3) clay loam, pale brown (10YR 6/3) moist; weak medium prismatic structure parting to moderate medium subangular blocky; very hard, very firm, very sticky and very plastic; few very fine tubular pores; 1 percent very fine masses of calcium carbonate; 1 percent rounded siliceous gravels; 1 percent very fine masses of salts; Sodium Adsorption Ratio is 29; slightly effervescent; moderately alkaline

TYPE LOCATION: Webb County, Texas; from the intersection of U. S. Highway 59 and Texas Highway 44 in Duval County; northwest 13.4 miles into Webb County on Texas Highway 44 to Pintas-Adami Road; north 3.1 miles on Pintas-Adami Road; 800 feet northwest in rangeland. Biel Lake NE, TX USGS topographic quadrangle; Latitude: 27 degrees, 58 minutes, 48.4 seconds N; Longitude: 98 degrees, 51 minutes, 39.7 seconds 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. 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 soil temperature: 22 to 23 degrees C (72 to 74 degrees F)
Particle size control section (weighted average)

Clay content: 40 to 55 percent
Rock Fragments: 0 to 5 percent

A (An where present) horizon
Hue: 10YR
Value: 3 or 4
Chroma: 1 or 2
Texture: clay loam or clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 5 percent
Base saturation: 90 to 100 percent
Calcium carbonate equivalent: 0 to 15 percent
Electrical Conductivity (dS/m): 0 to 8
Gypsum: 0 to 1 percent
Sodium Adsorption Ratio: 0 to 13
Reaction: slightly alkaline to moderately alkaline

Bnss horizon
Hue: 10YR
Value: 3 to 5
Chroma: 1 to 3
Texture: clay loam or clay
Clay content: 35 to 55 percent
Rock fragments: 0 to 5 percent
Base saturation: 90 to 100 percent
Calcium carbonate equivalent: 0 to 15 percent
Electrical Conductivity (dS/m): 8 to 20
Gypsum: 1 to 4 percent
Sodium Adsorption Ratio: 15 to 40
Reaction: slightly alkaline to moderately alkaline

Bknssz (Bnssz where present) horizon
Hue: 10YR or 2.5Y
Value: 4 to 7
Chroma: 1 to 4
Texture: clay loam or clay
Clay content: 35 to 55 percent
Rock fragments: 0 to 5 percent
Base saturation: 90 to 100 percent
Calcium carbonate equivalent: 0 to 15 percent
Electrical Conductivity (dS/m): 8 to 20
Gypsum: 1 to 4 percent
Sodium Adsorption Ratio: 15 to 40
Reaction: slightly alkaline to moderately alkaline

Bknz horizon
Hue: 10YR or 2.5Y
Value: 4 to 7
Chroma: 1 to 3
Texture: clay loam or clay
Clay content: 35 to 55 percent
Rock fragments: 0 to 5 percent
Base saturation: 90 to 100 percent
Calcium carbonate equivalent: 0 to 15 percent
Electrical Conductivity (dS/m): 8 to 20
Gypsum: 2 to 5 percent
Sodium Adsorption Ratio: 15 to 40
Reaction: slightly alkaline to moderately alkaline

COMPETING SERIES: These are the Arroyada (TX), Catarina (TX), Coquat (TX),
Cotulla (TX), Lasalle (TX), Mercedes (TX), Montell (TX), Victine (TX), and
Victoria (TX) series.
Arroyada soils: have an ochric epipedon; somewhat poorly drained; moist in the moisture control section for longer periods.
Catarina, Coquat, and Cotulla soils: have an ochric epipedon
Lasalle soils: have dominant subsoil colors of 7.5YR or redder.
Mercedes, Victine, and Victoria soils: are moist in the soil moisture control
section for longer periods.
Montell soils: have an ochric epipedon; not flooded.

GEOGRAPHIC SETTING:
Parent material: Clayey alluvium derived from the Tertiary aged sediments overlain with the Uvalde Gravel.
Landform: valley flat
Slope: 0 to 2 percent
Mean annual air temperature: 22 to 23 degrees C (72 to 74 degrees F)
Mean annual precipitation: 508 to 610 mm (20 to 26 in)
Frost-free period: 270 to 320 days
Elevation: 76 to 183 m (250 to 600 ft)
Thornthwaite annual P-E indices: 20 to 32

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arroyada (TX), Brundage (TX), Catarina (TX), and Montell (TX) series.
Arroyada soils: are on slightly lower positions and are moist for longer periods.
Brundage soils: are on slightly higher positions and have a natric horizon.
Catarina and Montell soils: occur on slightly higher positions and are not in floodplains.

DRAINAGE AND PERMEABILITY: Moderately well drained. Very slow permeability. Runoff is high on slopes less than 1 percent and very high on slopes of 1 to 2 percent. These soils are rarely or occasionally flooded.

USE AND VEGETATION: Used primarily for livestock grazing and wildlife habitat. The grasses consist primarily of buffalograss, sideoats grama, curlymesquite, hairy tridens, Southwestern bristlegrass, and threeawn. Woody vegetation is mostly acacia, condalia, prickly pear, mesquite, Texas persimmon, and huisache.

DISTRIBUTION AND EXTENT: Western Rio Grande Plain, Texas; LRR I, MLRA 83B; moderate extent.

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

SERIES ESTABLISHED: Duval County, Texas, 2008. This series was proposed in Duval County, Texas, 2003. The name is coined from the Montell series and Webb County.

REMARKS: These soils were previously included with the Montell series. Montell
soils are not flooded.

Diagnostic horizons and features recognized in this pedon are:

Particle size control section: 25 to 100 cm (10 to 40 in) (A2, Bnss and Bnssz
horizons)
Mollic epipedon: 0 to 28 cm (0 to 11 in) (A horizon).
Sodic feature: 28 to 203 cm (11 to 80 in) (Bnss, Bnssz, Bknssz, and Bknz
horizons).
Vertic features: Slickensides at 28 to 109 cm (11 to 46 in). (Bnss, Bnssz, and
Bknssz horizons).

ADDITIONAL DATA: NSSL data from Webb County (S03TX-479-001)

TAXONOMIC VERSION: Keys to Soil Taxonomy, Eleventh Edition, 2010.

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National Cooperative Soil Survey
U.S.A.