LOCATION VENUS TXEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Udic Calciustolls
TYPICAL PEDON: Venus loam--cropland. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 6 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; weak fine granular and fine subangular blocky structure; hard, friable; many wormcasts; few fragments of shells and fine slightly pitted calcium carbonate concretions; calcareous; moderately alkaline; abrupt smooth boundary. (3 to 8 inches thick)
A--6 to 14 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; hard, friable, crumbly; common granular wormcasts; few fine slightly pitted calcium carbonate concretions and fragments of shells; calcareous; moderately alkaline; gradual smooth boundary. (7 to 12 inches thick)
Bk1--14 to 30 inches; grayish brown (10YR 5/2) loam, dark grayish brown (10YR 4/2) moist; moderate fine subangular blocky and granular structure; hard, friable, crumbly; common wormcasts; few fine slightly pitted calcium carbonate concretions and fragments of shells; many films and threads and a few soft masses of calcium carbonate; 18 percent calcium carbonate equivalent; few pebbles of quartz; calcareous; moderately alkaline; gradual boundary. (6 to 22 inches thick)
Bk2--30 to 50 inches; very pale brown (10YR 7/3) loam, pale brown (10YR 6/3) moist; moderate very fine and fine granular structure; hard, friable, very crumbly; common filled worm channels; common fine, slightly pitted calcium carbonate concretions; many films and threads and common soft masses of calcium carbonate; 19 percent calcium carbonate equivalent; few pebbles of quartz; calcareous; moderately alkaline; gradual boundary. (8 to 28 inches thick)
BCk--50 to 60 inches; very pale brown (10YR 7/3) fine sandy loam, pale brown (10YR 6/3) moist; weak fine subangular blocky structure; hard, friable; lenses of fine quartz and limestone pebbles; common soft bodies of calcium carbonate; 20 percent calcium carbonate equivalent; calcareous; moderately alkaline.
TYPE LOCATION: Erath County, Texas; from the intersection of Farm Road 1189 and U.S. Highway 281 in Morgan Mill, 7.9 miles northeast on Farm Road 1189 to intersection with county road, 2.2 miles north and east on county road, 320 yards south in cropland.
RANGE IN CHARACTERISTICS: The solum ranges from 60 to about 80 inches thick. The mollic epipedon is 10 to 20 inches thick. In the control section the silicate clay content ranges from 18 to 30 percent. Siliceous pebbles range from none to a few. The calcium carbonate equivalent ranges from 15 to 40 percent.
The A horizon has hue of 7.5YR to 2.5Y, value of 4 or 5, and chroma of 2 or 3. It is loam or clay loam. Calcium carbonate concretions range from none to a few.
The Bk horizons have hue of 7.5YR to 2.5Y, value of 5 to 7, and chroma of 2 to 4. The texture is loam, sandy clay loam, or clay loam. Calcium carbonate concretions, films, threads, and soft masses range from 5 to about 20 percent by volume.
The BCk horizon has colors in shades of brown or yellow. It is fine sandy loam, loam, sandy clay loam, or clay loam. The calcium carbonate equivalent ranges from 10 to 60 percent. Some pedons are underlain by layers of sand and gravel at depths of about 4 feet to 8 feet.
COMPETING SERIES: There are no other series in this family. Similar series are the Bippus, Bolar, Clark, Engle, Hidalgo, Lewisville, Nuvalde, Quanah, and Sunev series. Bippus soils have Mollic epipedons thicker than 20 inches. Bolar and Sunev soils contain more than 40 percent calcium carbonate equivalent and Bolar soils have bedrock at a depth of 20 to 40 inches. Clark and Engle soils have sola less than 40 inches thick. Hidalgo soils have average annual soil temperatures of more than 72 degrees F. Lewisville, Nuvalde and Quanah soils have fine-silty control sections. Also, Bippus, Clark, Hidalgo, Quanah and Sunev soils occur in a drier climate.
GEOGRAPHIC SETTING: Venus soils are on nearly level to moderately sloping stream terraces and valley fill positions. Some areas adjacent to the stream channel are rarely to occasionally flooded for very brief periods in the spring and fall months. Slopes are dominantly 1 to 5 percent, but range from 0 to 8 percent. The soil formed in thick beds of unconsolidated calcareous, loamy alluvial sediments of Pleistocene age. The climate is moist subhumid with a mean annual precipitation of about 28 to 40 inches. Mean annual temperature ranges from 62 to 69 degrees F. Thornthwaite annual P-E indices are 44 to 64.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the similar Engle and Lewisville series, as well as the Altoga, Austin, Bosque, Houston Black, Karnes, and Lamar series. Altoga soils are fine-silty and have an Ochric epipedon. Austin soils have carbonatic mineralogy and are moderately deep over chalk. Bosque soils have dark colored A horizons thicker than 20 inches and an irregular distribution of organic matter. Houston Black soils have more than 35 percent clay and intersecting slickensides. Karnes and Lamar soils have an Ochric epipedon. Altoga, Engle, Karnes, Lamar, and Lewisville soils are on positions similar to Venus. Austin and Houston Black soils are on slightly higher positions. Bosque soils are on flood plains.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderate permeability.
USE AND VEGETATION: Mostly cultivated, mainly to small grains. Original vegetation was tall and mid grass and widely spaced live oak and other hardwoods.
DISTRIBUTION AND EXTENT: Mostly in The Blackland Prairies, Grand Prairie and eastern part of the Edwards Plateau in Texas and possibly in Oklahoma. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Bexar County, Texas; 1964.
REMARKS: Classification was changed 11/89 from Typic Calciustolls to Udic Calciustolls.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 14 inches
Calcic horizon - 14 to 60 inches
ADDITIONAL DATA: Lab data available from NSSL; Bell County, Texas No. 81P1582-1588, 18207-18216.