LOCATION COTULLA TX

Established Series
Rev. JWS-CKH-JBA
11/2013

COTULLA SERIES

The Cotulla series consists of very deep, moderately well drained, very slowly permeable soils that formed in calcareous, saline-sodic, clayey residuum derived from mudstone. These nearly level to gently sloping soils are on foot slopes and side slopes of broad interfluves. Slopes range from 0 to 5 percent. Mean annual precipitation is about 559 mm (22 in) and the mean annual temperature is about 21.7 degrees C (72 degrees F).

TAXONOMIC CLASS: Fine, smectitic, hyperthermic Sodic Haplusterts

TYPICAL PEDON: Cotulla clay on a linear, 0.5 percent slope in native rangeland; elevation is 108 meters (350 feet). (Colors are for dry soil unless otherwise stated.

A--0 to 18 cm (0 to 7 in); grayish brown (10YR 5/2) clay, grayish brown (10YR 5/2) moist; moderate fine and medium subangular blocky structure; very hard, firm; common very fine and fine roots; few snail shell fragments; thin surface crust; 9 percent calcium carbonate equivalent; nonsaline; strongly effervescent; moderately alkaline; clear smooth boundary. Thickness is 10 to 25 cm (4 to 10 in)

Bw--18 to 46 cm (7 to 18 in); grayish brown (10YR 5/2) clay, grayish brown (10YR 5/2) moist; moderate fine and medium angular blocky structure; extremely hard, very firm; few very fine and fine roots; few snail shell fragments; 10 percent calcium carbonate equivalent; nonsaline; exchangeable sodium percentage is 13; strongly effervescent; moderately alkaline; gradual wavy boundary. Thickness is 20 to 41 cm (8 to 16 in)

Bnssz--46 to 71 cm (18 to 28 in); light brownish gray (10YR 6/2) clay, grayish brown (10YR 5/2) moist; moderate fine and medium angular blocky structure; extremely hard, very firm; few very fine and fine roots; few prominent slickensides; few snail shell fragments; 8 percent calcium carbonate equivalent; slightly saline;exchangeable sodium percentage is 22; strongly effervescent; moderately alkaline; gradual wavy boundary. Thickness is 0 to 41 cm (0 to 16 in)

Bnssyz1--71 to 86 cm (28 to 34 in); brown (10YR 5/3) clay, brown (10YR 5/3) moist; moderate fine and medium angular blocky structure; extremely hard, very firm; few very fine and fine roots; few prominent slickensides and common wedge shaped peds; common fine distinct grayish brown (10YR 5/2) streaks; few threads of gypsum and other neutral salts; 10 percent calcium carbonate equivalent; moderately saline; exchangeable sodium percentage is 27; strongly effervescent; moderately alkaline; diffuse wavy boundary.

Bnssyz2--86 to 127 cm (34 to 50 in); pale brown (10YR 6/3) clay, brown (10YR 5/3) moist; weak fine and medium angular blocky structure; very hard, very firm; few very fine and fine roots; few intersecting slickensides and common wedge shaped peds; common fine distinct grayish brown (10YR 5/2) streaks; common fine threads and clusters of gypsum crystals and other salts; 9 percent calcium carbonate equivalent; moderately saline; exchangeable sodium percentage is 30; strongly effervescent; moderately alkaline; diffuse wavy boundary. Combined thickness of the Bnssyz is 36 to 112 cm (14 to 44 in)

Bnyz--127 to 203 cm (50 to 80 in); light yellowish brown (10YR 6/4) clay, light yellowish brown (10YR 6/4) moist; weak fine and medium angular blocky structure; very hard; very firm; few very fine roots; common fine irregular threads and clusters of gypsum crystals and other salts; 8 percent calcium carbonate equivalent; moderately saline; exchangeable sodium percentage is 30; strongly effervescent; moderately alkaline.

TYPE LOCATION: La Salle County, Texas; From the intersection of Texas Highway 97 and U.S. Highway 81 in Cotulla; 0.8 mile east on Texas Highway 97 to Farm Road 624; 13.3 miles southeast on Farm Road 624; 1.2 miles north on Farm Road 469; 250 feet west along south end of cultivated field; 100 feet south in rangeland. USGS topographic quadrangle: Charco Marrano Creek, Texas; Latitude: 28 degrees, 19 minutes, 23.9 seconds N; Longitude 99 degrees, 4 minutes, 55.7 seconds W.; Datum: WGS 84.

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: 22.2 to 24.4 degrees C (72 to 76 degrees F)
Solum thickness: ranges from 102 to 203 cm (40 to 80 in)
Depth to slickensides: 12 to 38 cm (4 to 15 in).
Cracks: 1 to 5 cm (0.4 to 2 in) wide at the surface when dry and extend to a depth of 51 cm (20 in) or more.
Depth to salt accumulations: 25 to 85 cm (10 to 33 in).
Electrical conductivity: increases with depth in the upper 102 cm (40 in).
Exchangeable sodium percentage: 15 or more in the upper 102 cm (40 in) of the solum (SAR of 13 or more )

Particle-size control section (weighted average)
Clay content: 35 to 60 percent
CEC/clay ratio: greater than 0.60

A horizon:
Hue: 10YR or 2.5Y
Value: 2 to 6
Chroma: 2 to 4
Texture: clay or clay loam
Clay content: 35 to 50
Calcium carbonate equivalent: 2 to 10 percent
Electrical conductivity (ds/m): 0.4 to 4
Sodium adsorption ratio: 0 to 4
Effervescence: slight or strong
Reaction: moderately alkaline

Bw horizon:
Hue: 10 YR to 2.5Y
Value: 3 to 6
Chroma: 2 to 4
Texture: clay
Clay content: 40 to 60 percent
Calcium carbonate equivalent: 5 to 20 percent
Electrical conductivity (ds/m): 0.5 to 4
Sodium adsorption ratio: 5 to 15
Effervescence: slight or strong
Reaction: moderately alkaline

Bnssyz and Bnyz horizons:
Hue: 10YR or 2.5Y
Value: 5 to 8
Chroma: 1 to 6
Texture: clay
Clay content: 40 to 60 percent
Rock fragments: 0 to 2 percent chert gravels
Vertic features: many streaks that have colors of the A and Bw horizons
Gypsum: 1 to 20 percent crystals
Salt: 1 to 20 percent masses
Calcium carbonate equivalent: 5 to 20 percent
Electrical conductivity (ds/m): 4 to 16
Sodium adsorption ratio: 13 to 24
Effervscence: strong
Reaction: moderately alkaline

BCyz and Cdyz horizons: (where present)
Hue: 2.5Y or 5Y
Value: 6
Chroma: 4
Texture: clay, silty clay
Clay Content: 40 to 60 percent
Rock fragments: 2 to 35 percent mudstone parachanners and 0 to 2 percent chert gravels
Gypsum: 1 to 10 percent crystals
Salt: 1 to 20 percent masses and 2 to 50 percent crystals and threads
Calcium carbonate equivalent: 5 to 20 percent
Electrical conductivity (ds/m): 4 to 16
Sodium adsorption ratio: 13 to 40
Effervescence: slight or strong
Reaction: moderately alkaline

COMPETING SERIES: These are the Arroyada (TX), Catarina (TX), Coquat (TX), Dosrios (TX), Duvert (I-TX), Lasalle (TX), Mercedes (TX), Montell (TX), Monwebb (TX), Victine (TX), and Victoria (TX) series in the same family.
Arroyada and Coquat soils: are somewhat poorly drained and formed in Holocene alluvium on flood plains
Catarina soils: are drier in the moisture control section.
Dosrios, Montell, Monwebb, Victine, and Victoria soils: have chroma of 1.5 or less in at least the upper 12 inches.
Duvert soils: have a paralithic contact between 50 to 100 cm (20 and 40 in) of the surface, and are well drained.
Lasalle soils: have hue of 7.5YR or redder in the B horizons.
Mercedes soils: are moist in the control section for longer periods of time throughout the growing season

GEOGRAPHIC SETTING:
Parent Material: calcareous, saline-sodic, clayey residuum derived from mudstone/claystone interbedded with sandstone
Landscape: inland dissected coastal plain
Landform: foot slopes and side slopes of broad interfluves
Slope: 0 to 5 percent
Mean annual precipitation: 483 to 660 mm (19 to 26 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.
Thornthwaite annual P-E indices: 27 to 32
Mean annual air temperature: 21.1 to 22.8 degrees C (70 to 74 degrees F)
Frost free period: 260 to 300 days
Elevation: 70 to 229 meters (230 to 750 feet)

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Chacon (TX), Maverick (TX), Moglia (TX), Montell (TX), and Pryor (TX) series.
Chacon and Pryor soils: have an argillic horizon.
Maverick soils: occur on slightly higher positions and have a densic contact from 50 to 100 cm (20 to 40 in).
Moglia soils: occur on slightly higher positions and have 18 to 20 percent silicate clay in the particle-size control section
Montell soils: occur on slightly lower positions and have chroma less than 1.5 in the upper 30 cm (12 in).

DRAINAGE AND PERMEABILITY: Moderately well drained. Permeability is very slow. Runoff is high on slopes of 0 to 1 percent and very high on 1 to 5 percent slopes.

USE AND VEGETATION: Used mostly as rangeland; however, a few areas are cultivated. Grain sorghum, small grain and perennial introduced grasses are grown in the cultivated areas. Native vegetation includes grasses such as curlymesquite, plains bristlegrass, lovegrass tridens, pink pappusgrass, white tridens, and threeawn. Woody plants include running mesquite, upright mesquite, twisted acacia, lotebush, condalia, guayacan, spiny hackberry, pricklypear, and dwarf screwbean. Saladillo (Texas varilla) occurs in some areas.

DISTRIBUTION AND EXTENT: Western and Central Rio Grande Plain, Texas; LRR I, MLRA 83B and 83C. large extent (about 117,000 acres correlated).

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

SERIES ESTABLISHED: Dimmit and Zavala Counties, Texas, 1982.

REMARKS: These soils were formerly included in Catarina series, but has a soil moisture regime that will support nonirrigated crops.

Edited 11/2013 (RFG-JBA): Edited Lat/Long, CCE, EC, SAR, and drainage class.

Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: 0 to 18 inches (A and Bw horizon).
Vertic features: Slickensides and wedge shaped peds occur between depths of 46 to 127 cm (18 to 50 in). (Bnssz, Bnssyz1, and Bnssyz2 horizon).
Sodic feature: SAR (sodium absorption ratio) of more than 13 within 102 cm (40 in) of the surface.

ADDITIONAL DATA: NSSL data from Live Oak County, TX (S92TX-297-001).

Taxonomic version: Keys to Soil Taxonomy, Eleventh Edition, 2010

National Cooperative Soil Survey
U.S.A.