LOCATION VALERA             TX

VALERA SERIES

TAXONOMIC CLASS: Fine, smectitic, thermic Petrocalcic Calciustolls

TYPICAL PEDON: Valera silty clay--rangeland. (Colors are for dry soil unless otherwise stated.)

A1--0 to 14 inches; dark grayish brown (10YR 4/2) silty clay, very dark grayish brown (10YR 3/2) moist; moderate very fine subangular blocky and granular structure in the upper part grading to very fine blocky in the lower part where peds are irregular in shape and have both acute and obtuse angles; very hard, very firm, but crumbly; few fine roots; calcareous, moderately alkaline; gradual wavy boundary. (10 to 20 inches thick)

A2--14 to 24 inches; brown (7.5YR 4/3) silty clay, dark brown (7.5YR 3/3) moist; moderate fine and very fine blocky structure, peds are irregular in shape and have prominent acute and obtuse angles; very hard, very firm; few fine concretions of calcium carbonate in the lower part; few fragments of limestone, calcareous; moderately alkaline; gradual wavy boundary. (10 to 24 inches thick)

Bw--24 to 30 inches; brown (7.5YR 5/4) silty clay, dark brown (7.5YR 4/4) moist; moderate fine and very fine blocky structure, peds have same shape as in horizon above; very hard, very firm; few fine concretions of calcium carbonate; few fragments of limestone; calcareous, moderately alkaline; abrupt irregular boundary. (0 to 18 inches thick)

Bkm--30 to 36 inches; pink (7.5YR 7/4) strongly cemented calcium carbonate; many imbedded fragments of limestone; few fine soft white bodies of calcium carbonate. (1 to 12 inches thick)

R--36 to 37 inches; fractured indurated limestone, partings are filled with reprecipitated calcium carbonate.

TYPE LOCATION: Menard County, Texas; approximately 16 miles west of Menard, Texas, in pasture, 0.5 mile northeast of county road, 4.9 miles north and 2.6 miles east of intersection of county road with Texas Highway 29, intersection is 19.2 miles west from intersection of U. S. Highway 83 and Texas Highway 29 in Menard.

RANGE IN CHARACTERISTICS: Solum thickness ranges from 20 to 40 inches and corresponds to the depth to the petrocalcic horizon. Coarse fragments of limestone comprise less than 15 percent of the control section. When dry, the soil has cracks from 1 to 2 cm wide and 25 to 50 cm deep, but the coefficient of linear extensibility is less than 0.07 in all horizons. Texture of all horizons ranges from silty clay to clay. Clay content ranges from 40 to 55 percent. Reaction is slightly alkaline or moderately alkaline.

The A1 horizon has hue of 10YR or 7.5YR, value of 3 to 5, and chroma 2 or 3. The A2 horizon has the same color range as the A1 horizon but also ranges to dark reddish brown (5YR 3/3). Moist consistence ranges from firm to very firm.

The Bw or Bk horizon is lacking in many pedons, but where present it is one or two units of color value higher than the A2 horizon.

The Bkm horizon ranges from strongly cemented to indurated calcium carbonate that is pink to white or very pale brown.

The R layer ranges from indurated limestone containing interbedded marls, to soft limestones having cemented upper layers, to a mixture of limestone fragments, marls, and cemented caliche.

COMPETING SERIES: The only series in the same family is Pratley. Similar soils are the Denton, Kavett, Mereta, Nuvalde, Purves, and Rowena series. Pratley soils have a paralithic contact under the petrocalcic horizon. Denton and Rowena soils lack petrocalcic horizons and in addition, Rowena soils have COLE values of 0.07 or greater. Kavett, Mereta, and Purves soils have sola thinner than 20 inches. Nuvalde soils have sola more than 40 inches thick and lack petrocalcic horizons.

GEOGRAPHIC SETTING: Valera soils are on nearly level to gently undulating uplands of the Edwards Plateau and Rolling Plains of Texas. Slopes are dominantly less than 3 percent, but they range up to 6 percent. The softer limestones and marly earths are presumed to be the parent material of the Valera soils. The mean annual precipitation ranges from 16 to 26 inches; The mean annual air temperature ranges from 64 to 68 degrees F. Frost free days range from 220 to 240 days and elevation ranges from 1500 to 2500 feet.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kavett, Mereta, and Rowena series, and the Tarrant and Tobosa series. Kavett, Mereta and Rowena series are on similar positions. Tarrant soils have sola thinner than 20 inches and are on higher positions. Tobosa soils have intersecting slickensides and are in lower positions.

DRAINAGE AND PERMEABILITY: Well drained, slow to medium runoff; moderately slow permeability.

USE AND VEGETATION: Mostly in native grasses. Vegetation is dominated by midgrass. Many pastures now have overstory of mesquite trees. Some areas are cultivated and used for growing small grains or sorghum.

DISTRIBUTION AND EXTENT: Edwards Plateau and Rolling Plains of Texas. The series is extensive.

MLRA OFFICE RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Coleman County, Texas; l922.

REMARKS: Soils formerly classified as shallow phases of the Valera series are now placed in the Kavett series.

Diagnostic horizons and features recognized in this pedon are:

Mollic epipedon - 0 to 24 inches.

Cambic horizon - 24 to 30 inches.

Petrocalcic horizon - 30 to 36 inches.

Lithic contact at 36 inches.