LOCATION LUCKENBACH TXEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, thermic Typic Argiustolls
TYPICAL PEDON: Luckenbach clay loam--cropland. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 8 inches; very dark grayish brown (10YR 3/2) clay loam, very dark brown (10YR 2/2) moist; moderate fine subangular blocky structure; slightly hard, firm, slightly sticky and plastic; common fine and medium roots; slightly alkaline; abrupt smooth boundary.
A--8 to 18 inches; dark brown (10YR 4/3) clay loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, firm, slightly sticky and plastic; few fine roots; slightly alkaline; clear smooth boundary. (combined thickness of the A horizon is 10 to 20 inches)
Bt--18 to 30 inches; reddish brown (5YR 5/4) clay, reddish brown (5YR 4/4) moist; moderate fine blocky and subangular blocky structure; hard, firm; few fine roots; patchy clay films; few fine calcium carbonate concretions; moderately alkaline; gradual smooth boundary. (10 to 22 inches thick)
Btk--30 to 38 inches; brown (7.5YR 5/4) clay, dark brown (7.5YR 4/4) moist; moderate fine subangular blocky and blocky structure; hard, firm; few fine roots; contains 5 percent by volume calcium carbonate concretions; violently effervescent; moderately alkaline; clear smooth boundary. (8 to 18 inches thick)
Bk1--38 to 45 inches; very pale brown (10YR 7/4) clay loam, light yellowish brown (10YR 6/4) moist; weak fine subangular blocky structure; hard, friable; few fine roots; contains 10 percent, by volume, calcium carbonate concretions; few limestone fragments; violently effervescent; moderately alkaline; clear smooth boundary. (5 to 10 inches thick)
Bk2--45 to 80 inches; very pale brown (10YR 7/3) clay loam; structureless; contains about 10 percent concretions and masses of calcium carbonate and 10 percent limestone gravel.
TYPE LOCATION: Gillespie County, Texas; from the intersection of U. S. Highway 290 and Texas Highway 16 in Fredericksburg, 8.5 miles southwest on Texas Highway 16, 3.7 miles west on county road, 200 feet south in cultivated field.
RANGE IN CHARACTERISTICS: The solum is 60 to 80 inches thick and the mollic epipedon ranges from 12 to 20 inches thick. Secondary carbonates are within a depth of 18 to 28 inches.
The A horizon has hue of 7.5YR and 10YR, value of 3 or 4, and chroma of 2 or 3. Texture is sandy clay loam, loam, or clay loam. Siliceous pebbles comprise 0 to 5 percent by volume. Reaction ranges from slightly acid through slightly alkaline.
The Bt horizon has hue of 5YR, 7.5YR, or 10YR, value of 4 or 5, and chroma of 2 to 4. Texture is clay or clay loam with clay content of 35 to 55 percent. Siliceous pebbles comprise 0 to 15 percent by volume. Reaction is slightly alkaline or moderately alkaline. Concretions and masses of calcium carbonate range from 0 to 10 percent by volume.
The Bk or Btk horizons are brownish or pinkish clay loam or clay. Rounded siliceous pebbles and fragments of limestone comprise 5 to 20 percent by volume of most pedons. Concretions and masses of calcium carbonate range from few to common.
COMPETING SERIES: These are the Bexar (TX), Frankirk (TX), Lawton (OK), Rowden (TX), Sagerton (TX), and Swenson (TX) series. Similar soils are the Abilene, Anocon, Blanket, and LaCasa series. Bexar, Rowden, and Swenson soils are 20 to 40 inches thick to bedrock. Frankirk soils have secondary carbonates below a depth of 28 inches and have 2.5YR hue in the argillic horizon. Sagerton soils have calcic horizons. Lawton soils do not have carbonates within a depth of 48 inches. Abilene and Blanket soils have mollic epipedons more than 20 inches thick. Anocon soils have secondary carbonates at depths greater than 28 inches and have formed in colluvium and residuum from sandstone and shale. LaCasa soils have a calcic horizon and a C horizon of altered Permian red bed sediments.
GEOGRAPHIC SETTING: Luckenbach soils are on valley fills and terraces. Slope gradients range from 0 to 5 percent. The soil formed in thick beds of calcareous clay loams and clays. Mean annual precipitation ranges from 26 to 30 inches and mean annual temperature ranges from 65 to 68 degrees F. Frost free days range from 215 to 235 days and elevation ranges from 500 to 2,175 feet. Thornthwaite annual P-E indices range from 36 to 46.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing Blanket series and the Heaton, Hensley, Krum, Pedernales, and Sunev series. Blanket soils are on similar or slightly lower positions. Heaton, Hensley, and Pedernales soils do not have mollic epipedons, and are typically on stream divides, low ridges, or nearby slopes. Krum soils have more clayey epipedons, lack argillic horizons and are on similar positions. Sunev soils have a calcic horizon, fine-loamy control section, and are below Luckenbach soils, usually on footslopes.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately slow. Runoff is negligible on 0 to 1 percent slopes, very low on 1 to 3 percent slopes, and low on 3 to 5 percent slopes.
USE AND VEGETATION: Mostly cropland used for growing small grain and grain sorghum. A few areas are in range. Native vegetation is post oak and mid and tall grasses.
DISTRIBUTION AND EXTENT: Mainly in the Central Basin, Eastern part of the Edwards Plateau, and southern part of the Grand Prairie of Texas. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Gillespie County, Texas; 1970.
REMARKS: Luckenbach soils were formerly in the Pedernales series which does not have a mollic epipedon. This soil was changed from a Typic Argiustoll to Udic Argiustoll in August 1989 because of change in Soil Taxonomy. However, most of the acreage and the typical pedon are located in the Typic Ustic moisture regime. Other areas are mainly on the Udic/Ustic and Typic/Ustic line. Therefore, we are classifying this soil in the Typic subgroup in 1990.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 18 inches. (A horizons)
Argillic horizon -18 to 38 inches. (Bt horizons)
Secondary forms of calcium carbonate in all horizons below 30 inches.
Soil Interpretation Record Number: TX0171