LOCATION DENVACA TXEstablished Series
TAXONOMIC CLASS: Fine, smectitic, hyperthermic Udertic Haplustalfs
TYPICAL PEDON: Denvaca clay loam--native pasture; (Colors are for moist soil unless otherwise stated).
A--0 to 6 inches; grayish brown (10YR 5/2) clay loam, dark grayish brown (10YR 4/2) moist; weak fine subangular blocky structure; very hard, firm; common fine and medium roots; few siliceous pebbles; strongly effervescent; moderately alkaline; clear wavy boundary. (4 to 12 inches thick)
Bt--6 to 22 inches; light brownish gray (10YR 6/2) clay loam, grayish brown (10YR 5/2) moist; weak fine and medium angular blocky structure; very hard, very firm; few fine roots; common faint clay films on surfaces of peds; 1 percent fine concretions and masses of calcium carbonate; few fine faint light yellowish brown (10YR 6/4) masses of iron accumulation with clear and sharp boundaries; 1 percent fine siliceous pebbles; slightly effervescent; moderately alkaline; clear wavy boundary. (0 to 20 inches thick)
Btkss1--22 to 43 inches; very pale brown (10YR 7/3) clay, pale brown (10YR 6/3) moist; weak coarse angular blocky structure; very hard, very firm; few fine roots; few slickensides; many prominent pressure surfaces; common vertical cracks partly filled with material from above; common faint clay films on surfaces of peds; 5 percent masses and concretions of calcium carbonate; common fine distinct brownish yellow (10YR 6/8) masses of iron accumulation with sharp boundaries; strongly effervescent; moderately alkaline; clear wavy boundary.
Btkss2--43 to 64 inches; very pale brown (10YR 7/3) clay, pale brown (10YR 6/3) moist; weak coarse angular blocky structure; very hard, very firm; common slickensides; many prominent pressure surfaces; few vertical cracks partly filled with material from above; common faint clay films on surfaces of peds; 3 percent concretions and masses of calcium carbonate; 1 percent black concretions 1 to 2 millimeters in diameter; common medium distinct brownish yellow (10YR 6/8) masses of iron accumulation with sharp boundaries; violently effervescent; moderately alkaline; clear wavy boundary.
Btkss3--64 to 70 inches; very pale brown (10YR 7/4) clay, light yellowish brown (10YR 6/4) moist; weak coarse angular blocky structure; very hard, very firm; common prominent slickensides; many prominent pressure surfaces; common faint clay films on surfaces of peds; 3 percent concretions and masses of calcium carbonate; 1 percent black concretions 1 to 2 millimeters in diameter; violently effervescent; moderately alkaline; clear wavy boundary. (combined thickness of Btkss horizons is 30 to 70 inches)
BCk--70 to 80 inches; pink (7.5YR 7/4) clay, light brown (7.5YR 6/4) moist; massive; very hard, very firm; 3 percent concretions of calcium carbonate; few black concretions 1 to 2 millimeters in diameter; violently effervescent; moderately alkaline.
TYPE LOCATION: Lavaca County, Texas; from Farm Road 531 in Sweet Home, 2.2 miles southwest on Farm Road 318, about 3.2 miles southeast on Farm Road 2543 to Pilot Grove, 1.4 miles south, 0.25 mile west, and 100 feet north on microknoll in a pasture. (USGS Sweet Home topographic quadrangle; Longitude 29N, 17, 13 and Latitude 97W, 04, 54)
RANGE IN CHARACTERISTICS: Solum thickness ranges from 60 to more than 80 inches. When dry, cracks extend to depths of 25 to 50 inches. Depth to slickensides and pressure surfaces range from 15 to 30 inches. Weighted average clay content of the particle-size control section ranges from 35 to 45 percent. Calcium carbonate clay in the particle-size control section ranges from 1 to 3 percent. Linear extensibility exceeds 6.0 centimeters within 40 inches of the surface.
The A horizon has hue of 10YR or 2.5Y, value of 5 to 7, and chroma of 1 to 3. Texture is clay loam or sandy clay loam. Clay content ranges from 20 to 30 percent. Some pedons have few fine concretions of calcium carbonate. Calcium carbonate equivalent ranges from 2 to 20 percent. Reaction ranges from neutral to moderately alkaline.
The Bt and Btk horizons have hue of 10YR, 2.5Y, or 5Y, value of 4 to 6, and chroma of 2 to 6. Texture is clay loam, sandy clay loam or clay. Clay content ranges from 30 to 45 percent, but averages greater than 35 percent. Calcium carbonate equivalent ranges from 10 to 35 percent by weight. Reaction is slightly alkaline or moderately alkaline.
The Btkss horizon has hue of 10YR to 5Y, value of 4 to 7, and chroma of 2 to 4. Texture is clay loam or clay. Clay content ranges from 35 to 45 percent. Calcium carbonate equivalent ranges from 15 to 35 percent by weight. Reaction is slightly alkaline or moderately alkaline.
The BCk horizon has hue of 7.5YR to 2.5Y, value of 4 to 7, and chroma of 1 to 4. Texture is clay loam or clay. Clay content ranges from 35 to 50 percent. Calcium carbonate equivalent ranges from 15 to 40 percent by weight. Reaction is slightly alkaline or moderately alkaline.
Where present, the C horizon is weakly consolidated shale that has clay loam or clay texture. It is mottled and streaked in shades of gray, brown, pink, and yellow. Some pedons have chroma that are 2 to 3 units higher than the BC horizon. Reaction ranges from slightly alkaline to moderately alkaline.
COMPETING SERIES: There are no competing series in the same family. Similar soils are the Bazette, Denhawken, Grainola, Lexton, Normangee, Ponder, and Wilson series. Bazette, Grainola, Lexton, Normangee, Ponder, and Wilson soils are in the thermic temperature regime. In addition, Grainola and Lexton soils have mixed mineralogy. Denhawken soils have a cambic horizon and a dryer moisture control section. In addition, Denhawken soils are associated with the Cook Mountain Formation.
GEOGRAPHIC SETTING: Denvaca soils are on nearly level upland plains. These soils occupy microhighs in complex soil areas. Slopes range from 1 to 3 percent. In native areas this soil occurs as mounds 2 to 8 inches higher than adjoining depressions. The soil formed in calcareous clayey materials of the Goliad and Fleming Formations. Mean annual precipitation ranges from 38 to 40 inches. Mean annual temperature ranges from 67 to 70 degrees F. Frost free days range from 270 to 280 days. Elevation ranges from 200 to 400 feet. Thornthwaite P-E Index range from 50 to 60.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dubina, Elmenwood, Frelsburg, and Hallettsville series. Dubina soils have sandy mollic epipedons and are on slightly higher landscape positions. Elmenwood soils are in depressional areas adjacent to the Denvaca soils in complex soil areas. Frelsburg soils are on slightly higher landscape positions. Hallettsville soils have mollic epipedons and are on similar landscape positions.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is slow. Runoff is medium.
USE AND VEGETATION: Mostly used for pasture. Pasture grasses include improved bermudagrass.
DISTRIBUTION AND EXTENT: Southern Blackland Prairie (MLRA 86B). The series is of major extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Colorado County, Texas; 1997
REMARKS: Denvaca soils were formerly included with the Denhawken series.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 6 inches thick. (A horizon)
Argillic horizon - 6 to 70 inches thick. (Bt, Btkss1, Btkss2, and Btkss3 horizons)
Calcic horizon - 22 to 80 inches thick. (Btkss1, Btkss2, and BCk horizons)
Udertic features - Slickensides and pressure surfaces below a depth of 22 inches, and cracks to the surface when dry.
ADDITIONAL DATA:
Soil Interpretation Record Number: TX1344