LOCATION BRENHAM TXEstablished Series
TAXONOMIC CLASS: Fine-silty, carbonatic, thermic Udic Calciustolls
TYPICAL PEDON: Brenham clay loam, on a convex 5 percent slope, in pasture. (Colors are for dry soil unless otherwise stated.)
A--0 to 10 inches; dark grayish brown (10YR 4/2), clay loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; hard, firm; many fine roots; many wormcasts; 16 percent calcium carbonate equivalent; calcareous; moderately alkaline; clear smooth boundary. (8 to 17 inches thick)
Bk1--10 to 28 inches; pale yellow (2.5Y 7/4) silty clay loam, light yellowish brown (10YR 6/4) moist; common vertical streaks of very dark grayish brown (10YR 3/2); moderate fine angular blocky structure; hard, firm; few soft masses of calcium carbonate; common fine roots; common fine pores; common wormcasts; few fine concretions of calcium carbonate; 52 percent calcium carbonate equivalent; calcareous; moderately alkaline; gradual wavy boundary. (5 to 18 inches thick)
Bk2--28 to 40 inches; pale yellow (2.5Y 7/4) silty clay loam, light yellowish brown (2.5Y 6/4) moist; moderate fine angular blocky structure; hard, firm; few fine roots, few fine pores; 20 percent soft masses of calcium carbonate; common concretions of calcium carbonate; 45 percent calcium carbonate equivalent; calcareous; moderately alkaline; gradual smooth boundary. (7 to 35 inches thick)
Bk3--40 to 48 inches; pale yellow (2.5Y 7/4) silty clay loam, light yellowish brown (2.5Y 6/4) moist; moderate fine blocky structure; hard, firm; 35 percent soft masses of calcium carbonate; common concretions of calcium carbonate; 48 percent calcium carbonate equivalent; calcareous; moderately alkaline; gradual smooth boundary. (0 to 15 inches thick)
2Bk4--48 to 61 inches; yellow (10YR 7/6) clay, brownish yellow (10YR 6/6) moist; weak coarse angular blocky structure parting to weak fine subangular blocky; very hard, firm; 30 percent soft masses and concretions of calcium carbonate; 29 percent calcium carbonate equivalent; calcareous; moderately alkaline; gradual smooth boundary. (5 to 15 inches thick.)
2Bk5--61 to 80 inches; yellow (10YR 7/6) silty clay, brownish yellow (10YR 6/6) moist; weak course angular blocky structure parting to weak fine subangular blocky; very hard, firm; few medium grooved intersecting slickensides that form wedge shaped peds; 20 percent soft masses and fine concretions of calcium carbonate; 24 percent calcium carbonate equivalent; calcareous; moderately alkaline.
TYPE LOCATION: Washington County, Texas; about 16 miles northeast of Brenham; from intersection of Farm Roads 1155 and 2726, go 1.2 miles northeast on Farm Road 2726, then 0.2 mile east on county road, then 0.8 mile southeast on unnumbered county road and 1200 feet southwest in a pasture.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 40 to more than 80 inches. Depth to the calcic horizon ranges from 10 to 30 inches. Calcium carbonate equivalent of the 10 to 40 inch control section ranges from 40 to more than 60 percent. Texture in the control section is clay loam, silty clay loam or clay with the total clay content ranging from 36 to 44 percent. Silicate clay percentage in the 10 to 40 inch control section ranges from 20 to 35 percent.
The A horizon has hue of 10YR or 2.5Y, value of 3 to 5, and chroma of 1 or 2. Texture is clay loam or silty clay loam.
The Bk or BCk horizons have hue of 10YR and 2.5Y value of 5 to 8, and chroma of 2 to 6. Texture is clay loam, silty clay loam or clay. Masses of iron accumulation range from none to common.
The 2Bk or 2BCk horizons have hue of 10YR or 2.5Y, value of 5 or 7, and chroma of 4 to 6. Texture is clay or silty clay, with total clay content of 40 to 60 percent.
Some pedons have a BCk horizon.
COMPETING SERIES: These include the Denton and Nuff series in the same family. Similar soils are the Austin, Bolar, Carbengle, Lewisville, Lott, Sunev, and Venus series. Austin soils are 20 to 40 inches to a paralithic contact of chalky limestone. Bolar, Carbengle, Sunev, and Venus soils have fine-loamy control sections. Nuff, Bolar and Carbengle soils have sola less than 40 inches thick. Lewisville soils have mixed mineralogy. Lott soils lack calcic horizons. Denton soils have a lithic contact at a depth between 40 and 60 inches.
GEOGRAPHIC SETTING: Brenham soils are on gently sloping uplands. Surfaces are convex and slope gradients are mainly 3 to 5 percent; however, they range from 1 to 8 percent. The soil formed in calcareous silty and clayey sediments of Miocene age mainly of the Lagarto formation. The climate is warm subhumid. The mean annual temperature ranges from 66 to 70 degrees F.and precipation ranges form 35 to 43 inches. Frost free days range from 240 to 270 days and elevation ranges from 300 to 600 feet. Thornthwaite P-E indices ranges from 48 to 64.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Carbengle series and the Bleiblerville, Frelsburg, Latium, and Renish series. Bleiblerville, Frelsburg, and Latium soils are more clayey and are on nearby gentle slopes. Carbengle soils are on associated similar slopes. Renish soils are on nearby slopes and have sola less than 20 inches thick over sandstone.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium to rapid. Permeability is moderate.
USE AND VEGETATION: Mostly used for rangeland and native pasture. Vegetation is mid and tall grasses such as little bluestem, indiangrass, and sideoats grama.
DISTRIBUTION AND EXTENT: Southeast Central Prairies of Texas. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Washington County, Texas; 1978.
REMARKS: The Brenham series was formerly included in the Lott or Heiden series.
Classification was changed 11/89 from Typic Calciustolls to Udic Calciustolls.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 10 inches (A horizon)
Calcic horizon - 10 to 80 inches (Bk and 2Bk horizons)
ADDITIONAL DATA: THD 73TX-477-2.