LOCATION TRACOSA                 TX

Established Series
Rev. GWC-KBH-AKS
07/2019

TRACOSA SERIES

The Tracosa series consists of very deep, very poorly drained soils that formed in loamy eolian deposits and storm washover sediments of Holocene age. These soils are on broad tidal flats on low coastal plains and on slightly depressional tidal areas on barrier islands. Slope ranges from 0 to 1 percent but mainly less than 0.5 percent. Mean annual precipitation is about 1295 mm (51 in) and mean annual air temperature is about 20.6 degrees C (69 degrees F).

TAXONOMIC CLASS: Fine, smectitic, nonacid, hyperthermic Sodic Endoaquents

TYPICAL PEDON: Tracosa mucky silty clay--on a 0.1 percent slope in a flat area, in grass; elevation is 2 m (6.5 ft) (Colors are for wet soil unless otherwise stated.)

Ag--0 to 20 cm (0 to 8 in); very dark grayish brown (2.5Y 3/2) broken face mucky silty clay, dark grayish brown (2.5Y 4/2), dry; massive; very firm, very sticky, very plastic; common very fine roots and common fine roots; noneffervescent; neutral; gradual smooth boundary. (8 to 46 cm [3 to 18 in] thick)

Cg1--20 to 64 cm (8 to 25 in); dark gray (5Y 4/1) broken face silty clay; massive; very firm, very sticky, very plastic; common very fine roots; 1 percent fine distinct olive (5Y 5/4), moist, masses of oxidized iron with diffuse boundaries in matrix; noneffervescent; moderately alkaline; gradual smooth boundary.

Cg2--64 to 120 cm (25 to 47 in); greenish gray (5GY 5/1) reduced silty clay; massive; very firm, very sticky, very plastic; common fine roots; 8 percent fine prominent olive yellow (5Y 6/6), moist, masses of oxidized iron with clear boundaries in matrix; 1 percent coarse irregular weakly cemented carbonate nodules that are pitted and resemble the shape of popcorn; noneffervescent; moderately alkaline; gradual smooth boundary. (combined thickness is 20 to 183 cm [8 to 72 in] thick)

Cg3--120 to 203 cm (47 to 80 in); greenish gray (5GY 5/1) reduced clay; massive; very firm, very sticky, very plastic; 8 percent medium prominent olive yellow (2.5Y 6/8), moist, masses of oxidized iron with sharp boundaries In matrix and 10 percent medium prominent olive yellow (2.5Y 6/6), moist, masses of oxidized iron with clear boundaries in matrix; 2 percent coarse irregular moderately cemented carbonate nodules that are pitted and resemble the shape of popcorn.; noneffervescent; moderately alkaline.

TYPE LOCATION: Galveston County, TX; from the intersection of Interstate Highway 45 and State Loop 197 about 5 miles south of La Marque, approximately 1.5 mile north on Loop 197; 0.4 mile east on plant road; 40 feet south in marsh.

USGS topographic quadrangle: Virginia Point, TX
Latitude: 29 degrees, 21 minutes, 3.1 seconds N
Longitude: 94 degrees, 55 minutes, 7.4 seconds W
Datum: WGS84

RANGE IN CHARACTERISTICS: Soil moisture: A peraquic moisture regime.
Mean annual soil temperature: 21.7 to 22.2 degrees C (71 to 72 degrees F)
The surface layer in some pedons has n-value of more than 0.7 but does not extend to a depth of 51 cm (20 in).

Ag horizon:
Hue: N, 2.5Yor 10YR
Value: 2 to 5; Where the value is 2 or 3, the thickness is less than 25cm (10 in).
Chroma: 2 or less.
Texture: muck, mucky clay loam, mucky silty clay, mucky clay, silty clay, or clay
Exchangeable sodium percent: more than 20 percent
Electrical conductivity: 15 to 50 dS/m
Soil reaction(pH): neutral to moderately alkaline (6.6 to 8.4)

Cg horizon:
Hue: N, 5Y, 5GY, 2.5Y, or 10YR
Value: 4 to 7
Chroma: 2 or less.
Texture: clay loam, silty clay loam, silty clay, or clay.
Redox concentrations: amount- 1 to 25 percent, shades of brown.
Redox depletions: amount- none to 25 percent; shades of gray
Masses of reduced iron: amount- none to 15 percent; shades of gray, green, or blue
Identifiable secondary carbonate: amount-0 to 5 percent; kind-nodules
Exchangeable sodium percent: more than 20 percent
Electrical conductivity: 15 to 45 dS/m
Soil reaction(pH): neutral to moderately alkaline (6.6 to 8.4)

Some pedons have brown calcareous layers below 102 cm (40 in).

COMPETING SERIES:
There are no competing series in the same family. Other competing series are the Barbary, Barrada, Follet, Gentilly, Harris, Levy, Placedo, Scatlake, and Tatlum series.
Barbary, Barrada, Gentilly, Levy, Scatlake, and Tatlum soils: have n-values of more than 0.7 between 20 to 51 cm (8 and 20 in) of the soil surface.
Follet soils: have a fine-silty control section.
Harris soils: have a mollic epipedon and an aquic moisture regime.
Placedo soils: are not flooded by daily tides.

GEOGRAPHIC SETTING:
Parent material: loamy eolian deposits and storm washover sediments of Holocene age
Landscape: low coastal plains or barrier islands
Landform: tidal flats
Slope: 0 to 1 percent but mainly less than 0.5 percent
Mean annual precipitation: 1194 to 1346 mm (47 to 53 in)
Thornthwaite P-E Index: exceed 50
Mean annual air temperature: 20.6 to 21.7 (69 to 71 degrees F)
Frost-free period: 301 to 365
Elevation: 0 to 2m (0 to 6.5 ft)

GEOGRAPHICALLY ASSOCIATED SOILS:
These are the competing Follet, Harris, Placedo, and Tatlum series and the Mustang, Narta, Velasco, and Veston series.
Follet and Tatlum soils: occur on the same position.
Harris, Mustang, Narta, Placedo, Velasco, and Veston soils: occur on a slightly higher position and have a water table that is below the soil surface at least some time during the year.
Mustang and Veston soils: have less than 35 percent clay in the particle-size control section.
Narta soils: have a natric horizon.

DRAINAGE AND PERMEABILITY:
Drainage class: very poorly
Permeability class: very slow
Runoff: high
Seasonal water table: permanent water table is at or slightly above the soil surface during low tides to 30 cm (12 in) above the surface during high tides. These soils remain saturated throughout the year.

USE AND VEGETATION:
Used for wildlife habitat land and livestock grazing. Native vegetation consists of smooth cordgrass, Salicornia, and Batis species.
Ecological sites assigned to phases and components of this series are listed below. Current ecological site assignments are in Web Soil Survey. Components of this series include the following ecological sites: Tidal Flats

DISTRIBUTION AND EXTENT:
General area: Along the Upper Gulf Coast in Southeast Texas
Land Resource Region: T-Atlantic and Gulf Coast Lowland Forest and Crop Region
Major Land Resource Aarea: MLRA 150B - Gulf Coast Saline Prairies
Extent: large
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Temple, Texas.

SERIES ESTABLISHED: Brazoria County, Texas; 1978.

REMARKS: These soils were formerly classified as a miscellaneous land type, Tidal flat, or were included with the Harris series. This soil has halic properties as described by J. R. Coover, et al., in SSSA Proceedings, 1975. The typical pedon site was changed during the update of MLRA 150B to a location with lab data.

Classification changed from Typic Haplaquents to Sodic Endoaquents 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 20 cm (0 to 8 in) (Ag horizon)
Sodic subgroup: Salinity from tidal flooding (ESP more than 20)
Peraquic moisture regime.

ADDITIONAL DATA: MLRA soil survey office lab data available on S2019TX1673102.

TAXONOMIC VERSION: Keys to Soil Taxonomy Twelfth Edition, 2014.

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National Cooperative Soil Survey
U.S.A.