LOCATION DUBINA TXEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Udic Paleustolls
TYPICAL PEDON: Dubina loamy fine sand--pasture. (Colors are for dry soil unless otherwise indicated.)
A--0 to 11 inches; dark grayish brown (10YR 4/2) loamy fine sand, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; loose, very friable; common fine and medium roots; medium acid; abrupt smooth boundary. (8 to 19 inches thick)
Bt1--11 to 17 inches; dark grayish brown (10YR 4/2) sandy clay, very dark grayish brown (10YR 3/2) moist; common medium distinct dark red (2.5YR 3/6) mottles; moderate medium prismatic structure parting to moderate medium subangular blocky; very had, firm; common fine and few medium roots; slightly acid; gradual smooth boundary.
Bt2--17 to 24 inches; brown (10YR 5/3) sandy clay, dark brown (10YR 4/3) moist; common medium distinct red (2.5YR 4/6), common medium faint grayish brown (10YR 5/2) and few fine faint reddish yellow (5YR 6/8) mottles; moderate medium subangular blocky structure; extremely hard, very firm; many fine roots; medium acid; gradual smooth boundary.
Bt3--24 to 33 inches; brown (10YR 5/3) sandy clay, dark brown (10YR 4/3) moist; common fine distinct red (2.5YR 4/8) and common medium faint grayish brown (10YR 5/2) mottles; moderate medium subangular blocky structure; very hard, firm; few fine roots; medium acid; gradual smooth boundary.
Bt4--33 to 43 inches; light brownish gray (10YR 6/2) sandy clay loam; grayish brown (10YR 5/2) moist; common medium distinct yellowish brown (10YR 5/8) and red (2.5YR 4/6) mottles; moderate medium subangular blocky structure; very hard, firm; few fine roots; medium acid; clear smooth boundary. The argillic horizon ranges from 24 to 40 inches thick.)
BC1--43 to 61 inches; strong brown (7.5YR 5/6) sandy clay loam, strong brown (7.5YR 4/6) moist; moderate fine subangular blocky structure; hard, friable; slightly acid; clear smooth boundary. (4 to 18 inches thick)
BC2--61 to 69 inches; brown (10YR 5/3) sandy loam, dark brown (10YR 4/3) moist; weak fine subangular blocky structure; slightly hard, very friable; neutral; abrupt smooth boundary. (0 to 10 inches thick)
C--69 to 80 inches; white (10YR 8/2) loamy sand, very pale brown (10YR 7/3) moist; structureless; loose, very friable; strongly effervescent; moderately alkaline.
TYPE LOCATION: Lavaca County, Texas; from U. S. Highway 90A in Hallettsville, 7.4 miles north on U. S. Highway 77, 1.2 miles east on New Kinkler Road to an unpaved road, then 1.6 miles north-northeast to a wooden farm gate, and 450 feet north of gate in bermudagrass pasture.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 50 to more than 60 inches.
The A horizon has hue of 7.5YR or 10YR, value of 4 or 5, and chroma of 2 or 3. Moist values are less than 3.5. Texture is loamy fine sand or loamy sand. Reaction ranges from moderately acid to neutral.
The upper part of the Bt horizon has hue of 7.5YR or 10YR, value of 4 or 5, and chroma of 1 to 3. Redoximorphic features in shades of brown, gray, red and yellow range from common to many. Most pedons have dark gray or very dark gray coatings on the exteriors of peds in this horizon. Texture is clay loam or sandy clay.
The lower part of the Bt horizon has hue of 7.5YR or 10YR, value of 5 or 6, and chroma of 2 to 8. Redoximorphic features in shades of yellow, brown, gray and red range from few to many. Some pedons have a mottled matrix in shades of yellow, brown, gray and red. Texture is sandy clay loam, clay loam, or sandy clay. Average clay content of the control section ranges from 35 to 45 percent. Reaction ranges from moderately acid to slightly alkaline in the upper Bt horizon and from medium acid to moderately alkaline in the lower Bt horizon. Some pedons contain masses and concretions of calcium carbonate below 36 inches.
The BC horizons have hue of 7.5YR or 10YR, value of 4 to 6 and chroma of 3 to 6. Texture is fine sandy loam, sandy clay loam or clay loam. Reaction ranges from moderately acid in the upper part to moderately alkaline in the lower part. Redoximorphic features in shades of yellow, brown, gray or red range from none to common. Some pedons have a mottled matrix in shades of yellow, brown, gray and red. These redoximorphic features are considered to be relict.
The C horizon is loamy sand, fine sandy loam, sandy clay or sandy clay loam. Some pedons contain interbedded layers of weakly consolidated packsand or weakly cemented sandstone. Reaction ranges from neutral to moderately alkaline.
COMPETING SERIES: There are no other series in the same family. Similar soils are the Elmendorf, Hallettsville, and Straber series. Elmendorf soils have mean annual soil temperatures greater than 72 degrees F and along with the Hallettsville series, have vertic properties. Straber soils lack mollic epipedons and have more acid reaction.
GEOGRAPHIC SETTING: Dubina soils are on nearly level to gently sloping uplands of the Coastal Plains. The soil formed in loamy and sandy marine sediments of the Goliad and Fleming Formations of the Pliocene Epoch. Slopes are smooth to slightly convex. Slope gradients are dominantly 1 to 3 percent, but range from 0 to 5 percent. Mean annual precipitation ranges from 30 to 40 inches and mean annual temperature ranges from 67 to 70 degrees F. Frost free days range from 260 to 280 days and elevation ranges from 200 to 600 feet. Thornthwaite annual P-E indices range from 44 to 60..
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Elmendorf, Hallettsville and Straber series and the Carbengle, Cuero and Denhawken series. Carbengle and Cuero soils have loamy control sections and occur at higher elevations on low ridges. Denhawken soils lack a mollic epipedon and occur in a complex at slightly higher elevations with the Elmendorf soils. Denhawken, Elmendorf and Hallettsville soils have vertic properties. Hallettsville soils occur on similar surfaces. Straber soils occur at higher elevations and lack a mollic epipedon.
DRAINAGE AND PERMEABILITY: Dubina soils are moderately well drained. Runoff is slow to medium. Permeability is slow.
USE AND VEGETATION: Dubina soils are used predominantly for rangeland and pasture. Native vegetation is mainly bluestems, paspalums, and panicums with scattered live oak trees. Pasture grasses are mainly improved species of bermudagrass and bahiagrass. A few areas are in cultivation, mainly to corn and hybrid forage sorghums.
DISTRIBUTION AND EXTENT: Southern Claypan area of south central Texas. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Lavaca County, Texas; 1986.
REMARKS: Classification changed to Udic Paleustolls because these soils are not continuously saturated in the mottled horizon for 90 days or more. Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the surface of the soil to a depth of approximately 17 inches (A and Bt1 horizons).
Abrupt texture change to clayey Bt at 11 inches.
Argillic horizon - The zone from approximately 11 to 43 inches (Bt1, Bt2, Bt3, and Bt4 horizons).