LOCATION TATLUM TXEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, nonacid, hyperthermic Typic Hydraquents
TYPICAL PEDON: Tatlum clay loam, on a smooth 0.1 percent slope, in grass. (Colors are for moist soil unless otherwise stated.)
Ag--0 to 18 inches; gray (10YR 5/1) clay loam, common medium distinct dark yellowish brown (10YR 4/4) mottles; massive; flows easily between fingers and leaves small residue in hand when squeezed; (n-value 1.0) slightly sticky; common fine and medium roots; strongly saline; moderately alkaline; clear smooth boundary. (6 to 2 inches thick)
Cg1--18 to 28 inches; gray (10YR 5/1) clay loam, massive; flows with some difficulty between fingers and leaves small residue in hand when squeezed; (n-value 0.8) slightly sticky; strongly saline; moderately alkaline; gradual smooth boundary. (10 to 22 inches thick)
Cg2--28 to 42 inches; gray (10YR 5/1) stratified clay loam with few strata of clay; common medium faint gray (N 5/09) mottles; massive; firm, alkaline; gradual smooth boundary. (10 to 24 inches thick)
Cg3--42 to 60 inches; gray (N 5/0) stratified clay loam and clay; common medium distinct strong brown (7.5YR 5/8) and many medium distinct grayish brown (10YR 5/2) mottles; massive; firm, slightly sticky and slightly plastic; few fine black concretions; strongly saline; moderately alkaline.
TYPE LOCATION: Brazoria County, Texas; about 12 miles east of Freeport; from the intersection of Cold Pass and Churchill Bayou and Follets Island, go across Cold Pass at a compass heading of 20 degrees, site is 60 feet north of the bank of Cold Pass.
RANGE IN CHARACTERISTICS: These soils have a peraquic moisture regime. All layers from 8 to 20 inches below the mineral surface have an n-value of more than 0.7. The n-value is less than 0.7 at some depth between 20 and 40 inches from the mineral surface. Some pedons have an organic mat of decomposing plant material 1 to 8 inches thick on the soil surface. Reaction ranges from neutral through moderately alkaline throughout the pedon. The electrical conductivity ranges from 25 to 90 mmhos and the exchangeable sodium is more than 30 percent throughout the control section. The sand fraction is mainly very fine sand throughout the control section. Clay content in the control section averages 18 to 35 percent.
The Ag horizon has hue of N through 10YR, values of 2 to 5, and chromas of 1 or less. The texture ranges from fine sandy loam through clay loam, or the mucky counterparts of these textures. Many pedons have few to many brown or gray mottles.
The Cg horizon has hue of N, 5Y, 5GY, 2.5Y, or 10YR, values of 4 through 7, and chroma of 2 or less. Where 2 chroma occurs, the horizon always contains mottles. The hue commonly changes on exposure to air. The texture ranges from very fine sandy loam through clay. Some pedons have mucky counterparts of these textures. The horizon is generally stratified. Mottles in shades of gray and brown range from few to many. Some pedons have brown clayey horizons below 40 inches which commonly are calcareous.
COMPETING SERIES: There are no competing series in the same family. Other competing series are the Barbary, Barrada, Caplen, Follet, Gentilly, Levy, Scatlake, and Tracosa series. Barbary, Barrada, Caplen, Gentilly, Levy, and Tracosa soils have more than 35 percent clay in the control section. Follet and Tracosa soils have n-values of less than 0.7 between 8 and 20 inches of the soil surface. Scatlake soils are in a very-fine family and have n-values greater than 1.0 throughout.
GEOGRAPHIC SETTING: Tatlum soils are on broad tidal areas in coastal marshes adjacent to bays and bayous. They are inundated with 2 to 12 inches of water during high tide. 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 exceeds 50.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Caplen, Follet, and Tracosa series and the Harris, Mustang, Narta, Placedo, and Veston series. All of these soils except Caplen have n-value of less than 0.7 within 8 to 20 inches of the soil surface. Follet and Tracosa soils are on similar landscapes. Harris, Mustang, Narta, Placedo, 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. Caplen soils are slightly higher.
DRAINAGE AND PERMEABILITY: Tatlum soils are very poorly drained. Runoff is very slow, and permeability is very slow. A permanent water table is at or slightly above the soil surface at 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 where the vegetation adds enough strength to the surface for support. 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. The series is inextensive.
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 Veston series. This soil has halic properties as described by J. R. Coover, et al., in SSSA Proceedings, 1975. A new subgroup has been proposed for addition to Soil Taxonomy.
Diagnostic horizons and features recognized in this pedon are:
Perquic moisture regime n-value greater than 0.7