LOCATION LOMALTA TXEstablished Series
TAXONOMIC CLASS: Very-fine, smectitic, hyperthermic Typic Natraquerts
TYPICAL PEDON: Lomalta clay--rangeland.
(Colors are for dry soil unless otherwise stated.)
A1--0 to 5 inches; gray (5Y 6/1) clay, dark gray (5Y 4/1) moist; moderate fine and medium angular and subangular blocky structure; very hard, very firm; very sticky, very plastic; 1/4 inch surface crust of gray (N 6/0) moist; many roots; saline; strongly effervescent; moderately alkaline; gradual smooth boundary. (3 to 7 inches thick)
Bzg--5 to 19 inches; gray (5Y 6/1) clay, gray (5Y 5/1) moist; weak coarse prismatic structure parting to moderate medium blocky; prisms are essentially uncoated; extremely hard, extremely firm; very sticky, very plastic; few fine pores; few fine roots; few films, threads and crystals of salt; saline; strongly effervescent; moderately alkaline; gradual smooth boundary. (12 to 24 inches thick)
Bsszg1--19 to 31 inches; gray (10YR 6/1) clay, gray (10YR 5/1) moist; moderate medium wedge structure; extremely hard, extremely firm; very sticky, very plastic; few fine pores; few roots; many prominent slickensides and parallelepipeds; few slightly darker streaks along old root channels and cracks; common films and threads of salts; saline; strongly effervescent; moderately alkaline; gradual smooth boundary. (8 to 12 inches thick)
Bsszg2--31 to 53 inches; gray (10YR 6/1) clay, gray (10YR 5/1) moist; moderate medium wedge structure; extremely hard, extremely firm; very sticky, very plastic; few roots; many prominent slickensides and parallelepipeds; 5 percent by volume masses and crystals of salts; saline; strongly effervescent; moderately alkaline; gradual wavy boundary. (18 to 27 inches thick)
Bzg--53 to 57 inches; light brownish gray (2.5Y 6/2) silty clay loam, grayish brown (2.5Y 5/2) moist; weak angular blocky structure; hard, firm; sticky and plastic; few roots; few distinct brownish yellow (10YR 6/6) iron concentrations and 20 percent by volume of gray (N 6/0) land crab krotovinas; few shiny pressure surfaces; common masses and crystals of salts; saline; strongly effervescent; moderately alkaline; gradual smooth boundary. (0 to 8 inches thick)
2C--57 to 72 inches; very pale brown (10YR 7/3) silt loam, light yellowish brown (10YR 6/4) moist; massive; land crab holes filled with light gray (N 6/0); saline; strongly effervescent; moderately alkaline.
TYPE LOCATION: Cameron County, Texas; from the intersection of State Highway 100 and Farm Road 1847 in Los Fresnos; 1.6 miles south on Farm Road 1847; 780 feet east in range.
RANGE IN CHARACTERISTICS: Solum thickness, and depth to loamy substrata, ranges from 40 to 80 inches. When dry, the soil has cracks 0.5 to 4 inches wide that extend to a depth of 30 inches or more. Slickensides begin at a depth of 15 to 30 inches below the surface. The 10- to 40-inch control section is clay with clay content ranging from 60 to 75 percent. Soil salinity ranges from moderately to strongly affected. Electrical conductivity (EC) ranges from 12 to 50 dS/m throughout the pedon. Exchangeable sodium (ESP) exceeds 15 percent in all horizons. Reaction is moderately alkaline or strongly alkaline throughout the pedon.
The A and B horizons have hue of 10YR to 5Y, or neutral, value 5 or 6, and chroma 0 or 1. Moist values are more than 3.5. The B horizons have redox features in shades of gray, brown, yellow, or neutral.
The 2C horizon has hue of 2.5YR to 10YR, value of 5 to 7, and chroma 2 to 3. Texture is silt loam or silty clay loam.
COMPETING SERIES: There are no other series in this family. Similar soils include the Benito, Mercedes, Montell, Monteola, and Victoria series. Benito soils are less saline. Mercedes, Montell, Monteola, and Victoria soils have less than 60 percent clay in the 10- to 40-inch control section. In addition, Montell, Monteola, and Victoria soils have cracks that remain open more than 150 days most years, and Monteola and Victoria soils have a mollic epipedon.
GEOGRAPHIC SETTING: Lomalta soils are on level to slightly depressional semi-marshy areas adjacent to the Gulf of Mexico a few feet above mean tide. The soil formed in clayey deltaic sediments. Slope is less than 1 percent. Mean annual precipitation ranges from 28 to 32 inches. Mean annual temperature ranges from 72 degrees to 74 degrees F. Frost-free days range from 330 to 350. Elevation ranges from 1 to 10 feet. Thornthwaite annual P-E indices range from 32 to 38.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing Benito and Mercedes series and the Harlingen, Latina, Point Isabel, and Sejita series. Harlingen soils have a epipedon with moist chroma of more than 1.5. Latina and Sejita soils have less than 35 percent clay in the 10- to 40-inch control section. Point Isabel soils are Inceptisols. Benito, Harlingen, and Mercedes soils occur at slightly higher elevations. Latina and Sejita soils occur on similar surfaces. Point Isabel soils occur on clay dunes.
DRAINAGE AND PERMEABILITY: Poorly drained. Runoff is negligible or ponded. Very slow permeability.
USE AND VEGETATION: Used for rangeland or wildlife land. Rangeland is of low carrying capacity. Vegetation is Gulf cordgrass, shoregrass, bushy sea-oxeye, and seashore saltgrass.
DISTRIBUTION AND EXTENT: Saline Coastal Prairies (MLRA 150B) of Texas and possibly in Mexico. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Cameron County (Brownsville area), Texas; 1907.
REMARKS: Classification changed from Udorthentic Pellusterts to Typic Natraquerts 11/2000 based on typifying pedon description. Further study and characterization data of the series is needed to verify hydrology and classification.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 5 inches (A horizon).
Cambic horizon - 5 to 57 inches (Bsszg and Bzg horizons).
Slickensides - 19 to 53 inches (Bsszg horizons).
ADDITIONAL DATA: none
TAXONOMIC VERSION: Soil Taxonomy, Second Edition, 1999.