LOCATION SET TXEstablished Series
The Set series consists of deep soils over claystone bedrock or dense clay, well drained, slowly permeable soils on plains and escarpments. They formed in clayey and loamy residuum from claystone bedrock. Slopes range from 1 to 40 percent.
TAXONOMIC CLASS: Fine-silty, carbonatic, thermic Typic Calciustolls
TYPICAL PEDON: Set clay, extremely stony, on a convex 20 percent slope, in rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 12 inches; dark grayish brown (10YR 4/2) clay, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; hard, firm; many fine and few medium roots; about 25 percent of surface covered by fragments of limestone about 10 to 36 inches across and 3 to 8 inches thick; about 2 percent fragments of limestone 0.1 inch to 2 inches across; calcareous; moderately alkaline; clear smooth boundary. (10 to 19 inches thick)
Bk1--12 to 26 inches; brown (10YR 5/3) clay, brown (10YR 4/3) moist; moderate fine and very fine subangular blocky structure; hard, firm; common fine and few medium roots; common fine pores; about 3 percent concretions and soft masses of calcium carbonate; about 20 percent fine limestone fragments less than 10 mm in diameter; about 2 percent limestone fragments 1 to 8 inches across; calcareous; moderately alkaline; gradual smooth boundary. (10 to 20 inches thick)
Bk2--26 to 38 inches; yellowish brown (10YR 5/4) silty clay, dark yellowish brown (10YR 4/4) moist; moderate fine and very fine subangular blocky structure; very hard, firm; common fine and few medium roots; few fine pores; many concretions and soft masses of calcium carbonate; calcareous; moderately alkaline; gradual smooth boundary. (10 to 20 inches thick)
BCk--38 to 44 inches; light yellowish brown (10YR 6/4) silty clay loam, yellowish brown (10YR 5/4) moist; moderate fine and medium subangular blocky structure; very hard, firm; few fine and medium roots; few fine pores; many concretions and soft masses of calcium carbonate; calcareous; moderately alkaline; gradual wavy boundary. (0 to 12 inches thick)
Cd--44 to 60 inches; light brownish gray (10YR 6/2) noncemented claystone bedrock and dense clay, grayish brown (10YR 5/2) moist; common streaks and mottles of light yellowish brown (10YR 6/4) and gray (10YR 6/1); material parts readily to medium angular fragments; few fine and medium roots in cracks; few concretions of calcium carbonate; calcareous; moderately alkaline.
TYPE LOCATION: Palo Pinto County, Texas; from the intersection of Texas Highways 16 and 108 in Strawn, 0.9 mile north on Texas Highway 16; 5.1 miles west on Farm Road 207; 1.2 miles north on county road and 15 feet east of road in rangeland.
RANGE IN CHARACTERISTICS: The thickness of the solum is 40 to 60 inches over claystone bedrock or dense clay and the mollic epipedon is 10 to 19 inches thick. The 10- to 40-inch control section is clay, silty clay, silty clay loam, or clay loam with calcium carbonate equivalent of 40 to about 65 percent. Silicate clay content ranges from 20 to 35
percent. Fragments of limestone cover 0 to 40 percent of the soil surface. Fragments range from less than an inch to 48 inches across the long axis but are mainly 10 to 36 inches across and 3 to 8 inches thick. Few to common fine fragments and a few coarse fragments are throughout the soil in some pedons.
The A horizon has hue of 10YR and 2.5Y, value of 3 to 5, and chroma of 2 or 3. Texture is clay, silty clay, silty clay loam or clay loam and their stony counterparts. Some pedons contain a few concretions of calcium carbonate.
The Bk horizon has hue of 10YR, 2.5Y, or 5Y, value of 5 or 6, and chroma of 2 to 4. Concretions and soft masses of calcium carbonate range from common to many. Texture is clay, silty clay, or clay loam.
The Cd horizon is in shades of olive, brown, or gray. It is claystone bedrock or claystone bedrock interbedded with dense clay and loamy materials. Concretions and soft masses of calcium carbonates range from few to common. Carbonates usually decrease with depth and are absent in some pedons.
COMPETING SERIES: There are no series in the same family. Closely similar soils are Austin, Bolar, Brenham, Chatt, Clark, Denton, Doss, Engle, Lewisville, Nuff, Nuvalde, Owens, Purves, Quanah, Somervell, and Venus series. Austin, Lewisville, and Quanah soils have less than 35 percent total clay in the 10- to 40-inch control section. Brenham soils formed in Tertiary age materials and receive more annual precipitation. Also, these soils have warmer mean annual temperatures. Chatt, Clark, Engle, Nuvalde and Venus soils have less than 40 percent carbonates in the 10- to 40-inch control section. Denton soils have a lithic contact of limestone at a depth of 40 to 60 inches. Bolar soils are underlain by limestone and marl at depths of 20 to 40 inches. Doss soils have a paralithic contact with limestone at depths of 11 to 20 inches. Nuff soils have sola 20 to 40 inches thick over marl and limestone. Purves soils are more clayey and have a lithic contact with limestone at depths of 8 to 20 inches. Somervell soils contain more than 35 percent coarse fragments in the 10- to 40-inch control section.
GEOGRAPHIC SETTING: Set soils are along gently sloping plains on foot slopes and steep stony escarpments. Slopes range from 1 to 40 percent. The soil is formed in clayey and loamy residuum over non cemented claystone bedrock. The climate is dry subhumid. The mean annual temperature ranges from 64 to 66 degrees F. The average annual precipitation is 25 to 29 inches. Thornthwaite P-E indices range from 36 to 48. Frost free period is 220 to 230 days and elevation ranges from 1100 to 1300 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Lewisville series, and the Hensley, Leeray, Owens, Palopinto, Thurber, and Truce series. Lewisville soils are lower in the landscape and associated with drainageways. Hensley and Palopinto soils are on gently sloping limestone ridgetops. Leeray soils have gilgai micro-relief and are below on broad nearly level and gently sloping uplands. Owens soils have light colored surfaces, contain less calcium carbonate, and occupy positions similar to Set soils. Thurber soils are below along broad, nearly level to gently sloping valleys. Truce soils have light colored loamy surfaces and are on positions similar to Set soils.
DRAINAGE AND PERMEABILITY: Set soils are well drained. Runoff is rapid and the permeability is slow.
USE AND VEGETATION: Used for rangeland, but a few small gently sloping areas are cultivated to small grain or forage sorghum. Native grasses consist of sideoats grama, little bluestem, silver bluestem, buffalograss, and Texas needlegrass. Forbs include Maximilian sunflower, Engelmann-daisy, dalea species, and western ragweed. Sumac species, oak, elm, and whitebrush also occur.
DISTRIBUTION AND EXTENT: North-central Texas, mainly in the North-central Prairie land resource area. The series is moderately extensive; more than 50,000 acres.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Palo Pinto County, Texas; 1979.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the A horizon from 0 to 12 inches.
Cambic horizon - the 12 to 26 inch zone.
Calcic horizon - the 26 to 44 inch zone.
Carbonatic mineralogy - the 10- to 40-inch control section contains more than 40 percent calcium carbonate equivalent.
Densic material - the 44 to 60 inch cd layer.