LOCATION KOPPERL TXEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, siliceous, active, thermic Udic Haplustalfs
TYPICAL PEDON: Kopperl gravelly sandy loam - rangeland.
(Colors are for dry soil unless otherwise stated.)
A1--0 to 6 inches; dark brown (7.5YR 4/2) gravelly sandy loam, dark brown (7.5YR 3/2) moist; weak fine subangular blocky and granular structure; very friable, nonsticky; many fine roots; organic stains; many rounded chert pebbles; slightly acid; gradual smooth boundary. (4 to 7 inches thick)
A2--6 to 14 inches; reddish brown (5YR 5/4) gravelly sandy loam, dark reddish brown (5YR 3/4) moist; weak fine granular structure; very friable, nonsticky; many fine roots; many rounded chert pebbles; slightly acid; gradual smooth boundary. (6 to 12 inches thick)
Bt1--14 to 26 inches; yellowish red (5YR 5/6) gravelly loam; yellowish red (5YR 4/6) moist; moderate medium subangular blocky structure; very friable, sticky; many fine roots; common continuous clay films; many rounded chert pebbles; neutral; gradual smooth boundary. (10 to 18 inches thick)
Bt2--26 to 40 inches; red (2.5YR 5/6) gravelly clay loam, red (2.5YR 4/6) moist; with few prominent strong brown (7.5YR 5/6) moist and brown (10YR 5/3) moist mottles; moderate medium subangular blocky structure; very firm, plastic; many woody roots; common continuous clay films; few dark red ironstone nodules; many rounded chert pebbles; slightly acid; gradual smooth boundary. (10 to 18 inches thick)
2Bt--40 to 54 inches; mottled brown (10YR 5/3) moist and reddish yellow (7.5YR 6/6) clay, strong brown (7.5YR 5/6) moist; strong coarse blocky structure; very firm, plastic; few woody roots; common continuous clay films; few flaggy limestone fragments up to 2 feet in diameter; prominent slickensides; common chert pebbles; neutral; abrupt wavy boundary. (7 to 18 inches thick)
2R--54 to 60 inches; hard white limestone. Upper two feet is platy limestone; below this is massive unrippable limestone.
TYPE LOCATION: Hill County, Texas; about 18 miles northwest of Hillsboro. About 8.5 miles north of Whitney on Farm Road 933, west at first road north of Huron store for about 6 miles to entrance of the Stiner Valley Ranch; site is 500 feet north of cattle guard.
RANGE IN CHARACTERISTICS: Solum thickness to fractured hard limestone ranges from 40 to 60 inches.
The A horizon has hue of 10YR to 5YR, value of 4 to 6, and chroma of 2 to 4. Where moist values and chromas are less than 3.5, the horizon is less than 7 inches thick. The texture is gravelly sandy loam or gravelly loam. Pebbles range from 20 to 50 percent by volume and consist mostly of rounded chert. The A horizon ranges from slightly acid through mildly alkaline.
The Bt1 and Bt2 horizons have hue of 7.5YR to 2.5YR, value of 4 to 6, and chroma of 4 to 8. Few or common mottles of strong brown (7.5YR 5/6) or brown (10YR 5/3) are present in the Bt2 horizon of most pedons. The Bt1 horizon is gravelly loam or gravelly clay loam. The Bt2 horizon is gravelly clay loam, very gravelly clay loam, gravelly clay, or very gravelly clay. The clay content of the fine earth fraction of the upper 20 inches of the Bt horizon is 18 to 35 percent. Coarse fragments comprise 35 to 50 percent of the control section. Reaction ranges from strongly acid through neutral.
The 2Bt horizon is generally mottled in colors of brown, strong brown, light brown, reddish yellow or reddish brown. It is clay or gravelly clay and ranges from slightly acid through mildly alkaline and is calcareous in the lower part of some pedons.
The 2R layer is white, hard limestone that is fractured in the upper 10 to 30 inches and massive below.
COMPETING SERIES: There are no competing series in the same family. Similar soils are the Brisco, Click, Dina, Nocken, Riesel, and Rumple series. Brisco, Dina and Rumple soils have mollic epipedons and have more than 35 percent clay in the control section. Click soils have mixed mineralogy and have a lithic contact to fractured granite. Nocken and Riesel soils have more than 35 percent clay in the control section.
GEOGRAPHIC SETTING: The Kopperl soils are on old nearly level to gently sloping high stream terraces. In places these terraces occur as remnants on limestone ridges. The soil formed in gravelly stream deposits laid down over limestone of Lower Cretaceous age. Slope ranges from 0 to about 3 percent but is mainly about l percent. Climate is moist subhumid. Average annual precipitation ranges from 28 to 35 inches. Mean annual air temperature ranges from 64 to 69 degrees F. Thornthwaite annual P-E index ranges from 48 to 62.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Riesel soils of the competing series and the Bastrop, Gasil, and Travis series. Bastrop, Gasil, and Travis soils lack 35 percent coarse fragments in the control section.
DRAINAGE AND PERMEABILITY: Well drained, slow runoff, moderately slow permeability.
USE AND VEGETATION: Mostly in rangeland and unimproved pastures. Native vegetation is mainly little bluestem, briers, grape, and mesquite, postoak, and liveoak trees.
DISTRIBUTION AND EXTENT: Central Texas, on old high stream terraces and terrace remnants along the Brazos River. The soils are of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Hill County, Texas; 1975.
REMARKS: These soils were formerly included in the Riesel series.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 14 inches.
Argillic horizon - 14 to 54 inches.
Lithic contact to limestone - 54 inches.
Additional Data: Texas Highway Department Lab. No.'s 73-49-R, 73-50-R, and 73-51-R. NSSL No. S73TX-109-3.