LOCATION OAKALLA TXEstablished Series
TAXONOMIC CLASS: Fine-loamy, carbonatic, thermic Cumulic
Haplustolls
TYPICAL PEDON: Oakalla silty clay loam--cropland. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 8 inches; dark grayish brown (10YR 4/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; hard, friable, sticky and plastic; common very fine and fine roots; common fine pores; few very fine weakly cemented masses of calcium carbonate; violently effervescent; moderately alkaline; about 33 percent calcium carbonate equivalent; abrupt smooth boundary. (5 to 15 inches thick)
Ak1--8 to 16 inches; dark grayish brown (10YR 4/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; hard, friable, sticky and plastic; common very fine and fine roots; common fine pores; few very fine weakly cemented masses of calcium carbonate; violently effervescent; moderately alkaline; about 33 percent calcium carbonate equivalent; gradual smooth boundary. (7 to 20 inches thick)
Ak2--16 to 23 inches; dark grayish brown (10YR 4/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; hard, firm, sticky and plastic; common very fine and fine roots; common fine pores; few very fine weakly cemented nodules of calcium carbonate; violently effervescent; moderately alkaline; about 41 percent calcium carbonate equivalent; gradual smooth boundary. (5 to 12 inches thick)
Bk1--23 to 53 inches; brown (10YR 5/3) silty clay loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; hard, firm, sticky and plastic; few very fine roots; few fine pores; few films and threads of calcium carbonate and a few weakly cemented nodules of calcium carbonate; few shell fragments; few dark streaks of A material; violently effervescent, moderately alkaline; about 50 percent calcium carbonate equivalent; gradual smooth boundary.
Bk2--53-80 inches; yellowish brown (10YR 5/4) silty clay loam, dark yellowish brown (10YR 4/4) moist; moderate fine and medium subangular blocky structure; hard, friable, sticky and plastic; few very fine roots; few fine pores; about 3 percent by volume films, threads, and soft masses of calcium carbonate, mainly in the lower part; few strongly cememted nodules of calcium carbonate; moderately alkaline; violently effervescent.
TYPE LOCATION: Blanco County, Texas; approximately 0.5 mile west of Hye, Texas on U.S. Highway 290 to intersection of Ranch Road 1. About 0.1 mile west on Ranch Road 1, then 150 feet north in cultivated field. (Also 75 feet north of fenceline corner post)
RANGE IN CHARACTERISTICS: The solum thickness is 60 to more than 80 inches. The calcium carbonate equivalent of the 10 to 40 inch control section averages from 40 to 60 percent. The mollic epipedon is more than 20 inches thick. Limestone pebbles comprise 0 to 10 percent of any horizon.
The Ap and Ak horizons have hue of 10YR, value of 2 to 5 and chroma of 1 to 3. Texture is loam, clay loam, silty clay loam, silty clay or clay containing from 25 to 45 percent clay. An estimated 5 to 12 percent of the clay is carbonate clay.
The Bk horizon has hue of 10YR, value of 3 to 6 and chroma of 2 to 4. Texture is loam, clay loam, or silty clay loam.
Some pedons have Ab horizons below 30 inches.
COMPETING SERIES: There are no competing series in this family. Similar series in other families are Bippus, Bosque, Frio, Gageby, and Seguin series. Bippus, Bosque, Frio, and Gageby soils have less than 40 percent calcium carbonate in the control section. In addition, Bippus and Gageby soils are dry in the moisture control section for longer periods of time. Seguin soils have mollic epipedons less than 20 inches thick.
GEOGRAPHIC SETTING: Oakalla soils are along flood plains of streams that drain areas of soils developed over limestone and marl. Slopes range from 0 to 2 percent. The soil formed in loamy calcareous alluvium. Mean annual precipitation ranges from 24 to 34 inches. The mean annual temperature ranges from 64 to 70 degrees F. Frost free days range from 210 to 240. Elevation ranges from 800 to 2,000 feet above sea level. The annual Thornthwaite P-E indices range from 36 to 46.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing Bosque, Frio, and Seguin series and Clairemont and Lewisville series. Bosque, Clairemont, Frio, and Seguin soils are in similar positions but the alluvial sediments are from different sources. Clairemont soils lack mollic epipedons. Lewisville soils occur on adjacent uplands and have mollic epipedons less than 20 inches thick.
DRAINAGE AND PERMEABILITY: The soil is well drained. Permeability is moderate. Runoff is negligible on 0 to 1 percent slopes and very low on 1 to 2 percent slopes. The soil floods at 1 to 10 year intervals, except where protected by dams.
USE AND VEGETATION: Most areas are being used for farmland, pastureland and rangeland. The areas farmed are mainly in sorghums and small grains. Some areas are used for improves pastures. Native trees are scattered elm, pecan, hackberry, and cottonwood. Grasses include little bluestem, switchgrass, indiangrass, and Texas wintergrass.
DISTRIBUTION AND EXTENT: This soil occurs mainly in the Grand Prairie and Edwards Plateau areas of Texas. It is of moderate extent with over 70,000 acres correlated.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Blanco County, Texas; 1977.
REMARKS: Oakalla soils were included with Bosque and Frio soils. Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 23 inches (A and Ak horizons)
SOIL INTERPRETATION RECORD: TX0708