LOCATION TRACOSA TXEstablished Series
TAXONOMIC CLASS: Fine, smectitic, nonacid, hyperthermic Sodic Endoaquents
TYPICAL PEDON: Tracosa mucky clay--on a flat area, in grass.
(Colors are for wet soil unless otherwise stated.)
Ag--0 to 4 inches; dark gray (10YR 4/1) mucky clay; massive; flows easily between fingers and leaves small residue in hand when squeezed (n-value 0.8); slightly sticky; many medium and fine roots; strongly saline; slightly alkaline; clear smooth boundary. (3 to 18 inches thick)
Cg1--4 to 19 inches; gray (10YR 5/1) clay; massive; firm, very sticky and very plastic; common fine roots; strongly saline; moderately alkaline; gradual smooth boundary. (8 to 23 inches thick)
Cg2--19 to 42 inches; gray (10YR 5/1) clay; massive; firm, very sticky and very plastic; common fine distinct brown iron concentrations; strongly saline; moderately alkaline; gradual smooth boundary. (10 to 42 inches thick)
Cg3--42 to 62 inches; gray (10YR 5/1) clay; massive; firm, very sticky and very plastic; few fine distinct brown iron concentrations and few fine prominent dark greenish gray iron depletions; strongly saline; moderately alkaline.
TYPE LOCATION: Brazoria County, Texas; about 15 miles east of Angleton; 4,500 feet southwest along Intracoastal waterway from intersection of Intracoastal Waterway and Bastrop Bayou; 1,400 feet east along dredged channel; site is 600 feet south of channel bank in a saline marsh.
RANGE IN CHARACTERISTICS: These soils have a peraquic moisture regime. The surface layer in some pedons has n-value of more than 0.7 but does not extend to a depth of 20 inches. Most pedons typically have a peaty or mucky surface layer 2 to 8 inches thick. Reaction ranges from neutral to moderately alkaline throughout. The electrical conductivity ranges from 20 to 90 dS/m, and the exchangeable sodium is more than 20 percent throughout the control section.
The Ag horizon has hue of N or 10YR, value of 2 to 5, and chroma of 2 or less. Where the value is 2 or 3, the thickness is less than 6 inches. The texture ranges from mucky clay loam to clay.
The Cg horizon has hue of N, 5Y, 5GY, 2.5Y, or 10YR, value of 4 to 7, and chroma of 2 or less. The texture is clay loam, silty clay loam, silty clay, or clay. Redox features range from none to many in shades of gray, brown, and greenish gray. Some pedons have loamy horizons below 40 inches, and some pedons have brown calcareous layers below 40 inches.
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 8 and 20 inches 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: Tracosa soils are on broad tidal areas in coastal saline marshes adjacent to bays and bayous. They are inundated with 2 to 12 inches of water during the daily high tides. One or two inches of water usually remain on the surface during low tides. Slopes are less than 0.5 percent. Mean annual precipitation ranges from 40 to 65 inches. Mean annual temperature is 72 degrees to 75 degrees F. Thornthwaite annual P-E indices exceed 50.
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: Tracosa soils are very poorly drained. Runoff is negligible or ponded, and permeability is very slow. A permanent water table is at or slightly above the soil surface during low tides to 12 inches above the surface during high tides.
USE AND VEGETATION: Used mainly as wildlife land. A few areas are grazed by livestock. Native vegetation is dominated by smooth cordgrass. Other plants include Salicornia and Batis species.
DISTRIBUTION AND EXTENT: Along the Upper Gulf Coast in Southeast Texas (MLRA 150B and MLRA 151). The series is extensive.
MLRA OFFICE 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.
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:
Peraquic moisture regime
Ochric epipedon-0 to 4 inches (Ag horizon).
Sodic subgroup--Salinity from tidal flooding (ESP more than 20).
ADDITIONAL DATA: NSSL data from Brazoria County, TX (S78TX-039-095).
TAXONOMIC VERSION: Soil Taxonomy, Second Edition, 1999.