LOCATION SAN SABA TX+OKEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Leptic Udic Haplusterts
TYPICAL PEDON: San Saba clay--cropland. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 4 inches; dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; moderate fine and medium granular structure; extremely hard, very firm; few fine roots; very slightly effervescent; slightly alkaline; clear smooth boundary. (4 to 6 inches thick)
A--4 to 19 inches; very dark gray (10YR 3/1) clay, black (10YR 2/1) moist; moderate medium angular blocky structure; extremely hard, very firm; few fine roots; streaks of dark gray in old crack fillings; common pressure faces; few fine iron-manganese concretions; very slightly effervescent; slightly alkaline; gradual wavy boundary. (8 to 26 inches thick)
Bss--19 to 35 inches; dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; common prominent slickensides and wedge shaped peds tilted 30 to 45 degrees from horizontal, these part to moderate fine angular blocky structure; extremely hard, very firm; few calcium carbonate concretions; few fine iron-manganese concretions; slightly effervescent; moderately alkaline; abrupt smooth boundary. (12 to 20 inches thick)
R--35 to 38 inches; gray indurated fractured limestone; fractures about 8 to 20 inches apart; hardness of about 3 Mohs scale.
TYPE LOCATION: Bell County, Texas; from junction of Interstate 35 and Texas Highway 36 in Temple; 6 miles northwest on Texas Highway 36 to Texas Highway 317; 1.1 miles north on Texas Highway 317 to private road; 1,600 feet west of junction with private road. (Latitude 31N, 10, 33; Longitude 97W, 25, 06)
RANGE IN CHARACTERISTICS: Thickness of the soil to a lithic contact of limestone or limestone interbedded with clay or chalk ranges from 24 to 40 inches. When dry, these soils have cracks from 1 to 3 inches wide that extend from the surface to depths of 20 inches or more. Cracks open and close on the average more than once each year, and remain open from 90 to 150 cumulative days in most years. Undisturbed areas have gilgai microrelief of knolls 3 to 6 inches higher than depressions, and the distance between the center of the knolls and the center of the depressions ranges from 6 to 12 feet. Slickensides are between a depth of 10 inches and the limestone. Clay content ranges from 45 to 60 percent. The solum is slightly to moderately alkaline and effervescent, but some pedons are noneffervescent to depths of 20 inches. Some pedons contain 5 to 10 percent of fragments of limestone ranging from 1/2 to 2 inches in diameter. Iron-manganese concretions range from few to common.
The A horizons have hue of 10YR, value of 3 or 4, and chroma of 1, and are more than 12 inches thick in more than half of each pedon.
The Bss horizon has hue of 10YR to 5Y, value of 4 or 5, and chroma of 1 to 3. Most pedons that have chroma of 2 or 3 are distinctly mottled with gray.
The R horizon is indurated limestone that is coarsely fractured.
COMPETING SERIES: These are the Anhalt, Crawford, Dalco, Greenvine and Vertel soils in the same family and the similar Dephalt series. Anhalt, Crawford and Dephalt soils have hue of 7.5YR or redder throughout. Aldo, Anhalt soils contain over 60 percent clay in the control section. Dalco soils have a paralithic contact with chalk. Greenvine soils have a paralithic contact with tuffaceous siltstone or sandstone. Vertel soils have a paralithic contact with shale and is in a very-fine family.
GEOGRAPHIC SETTING: San Saba soils are on nearly level or gently sloping uplands. Slope gradients range from 0 to 5 percent, but are dominantly from 0.5 to 2 percent. The soil formed in calcareous clays underlain by hard limestone at depths of 24 to 40 inches. Mean annual rainfall is 25 to 38 inches. The mean annual temperature is 64 degrees to 70 degrees F. and frost free days range from 230 to 250. Elevation ranges from 700 to 1300 feet above sea level. Thornthwaite P-E indices are 40 to 64.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Crawford series and the Bolar, Denton, Eckrant, Krum, and Purves series. Bolar soils have more than 40 percent carbonates and do not have slickensides. Denton soils are deep and in a fine-silty family. Eckrant soils have clayey-skeletal sola less than 20 inches thick. Krum soils are very deep. Purves soils have sola less than 20 inches thick. Denton soils are on slightly higher positions. Bolar, Eckrant, and Purves soils are on about the same position as San Saba soils. Crawford and Krum soils are slightly lower in the landscape.
DRAINAGE AND PERMEABILITY: This soil is moderately well drained. Runoff is low on slopes less than 1 percent, medium on 1 to 3 percent slopes, and high on 3 to 5 percent slopes. Permeability is very slow when the soil is saturated and rapid when it is dry and cracked.
USE AND VEGETATION: In cultivation, pasture and range. Cultivated crops are mostly grain sorghum, corn, small grain, and cotton. Native rangeland is mid and tall grasses with a widely spaced overstory of live oak. Most pasture areas are planted to coastal bermudagrass.
DISTRIBUTION AND EXTENT: Central Texas and southern Oklahoma. In the Edwards Plateau, the Grand Prairie and small areas in the Texas Blackland Prairies. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: San Saba County, Texas; 1916.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 35 inches, moist chroma of less than 1.5 in the upper 12 inches in more than half of each pedon.
Vertisol feature - slickensides at depths of 19 to 35 inches. High shrink-swell potential and cracks that are 1/2 to 1 inch wide at a depth of 12 inches or more during dry periods in most years.
Lithic contact feature - 35 inches.
SIR Number. TX0348, TX1010 (Stony)