LOCATION CLEMVILLE TXEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, hyperthermic Fluventic Eutrudepts
TYPICAL PEDON: Clemville silty clay loam--cropland.
(Colors are for moist soil unless otherwise stated.)
Ap--0 to 6 inches; dark brown (7.5YR 4/4), silty clay loam, brown (7.5YR 5/4) dry; weak fine granular structure; hard, friable; many fine roots; many very fine pores; few fragments of snail shells; common wormcasts; strongly effervescent, moderately alkaline; abrupt smooth boundary. (3 to 10 inches thick)
A--6 to 12 inches; dark brown (7.5YR 4/4) silty clay loam, brown (7.5YR 5/4) dry; weak fine granular structure; hard, friable; many fine roots; many fine and very fine pores; few fragments of snail shells; many wormcasts; strongly effervescent, moderately alkaline; clear smooth boundary. (0 to 8 inches thick)
Bw--12 to 30 inches; stratified light brown (7.5YR 6/4) silt loam, few thin lenses of reddish brown (5YR 5/4) and brown (7.5YR 5/4) silty clay loam; massive when moist, weak coarse subangular blocky when dry; breaks to platy fragments along some bedding planes; hard, friable, nonsticky and nonplastic; few fine roots; common very fine pores; few fragments of snail shells; common wormcasts; many horizontal bedding planes; strongly effervescent, moderately alkaline; abrupt smooth boundary. (12 to 30 inches thick)
Ab--30 to 50 inches; dark brown (7.5YR 3/3) silty clay, dark brown (7.5YR 4/3) dry; moderate medium and fine blocky structure; very hard, firm; few fine roots; common wormcasts; few strongly cemented concretions of calcium carbonate, few distinct coats of calcium carbonate on surfaces of peds, strongly effervescent, moderately alkaline; gradual smooth boundary. (0 to 30 inches thick)
Bb--50 to 62 inches; reddish brown (5YR 4/3) silty clay, reddish brown (5YR 5/3) dry; weak medium blocky structure; very hard, firm; few strongly cemented concretions of calcium carbonate; thin distinct calcium carbonate coats on surfaces of peds; strongly effervescent, moderately alkaline.
TYPE LOCATION: Wharton County, Texas; from Wharton, Texas, about 15 miles northwest on Farm Road 102 to the intersection of Farm Road 102 and Farm Road 26l4, 2.0 miles west on Farm Road 2614, south 1.0 mile on a gravel road, 200 feet west of gravel road in cultivated field.
RANGE IN CHARACTERISTICS: Depth to horizons with more than 35 percent clay ranges from 24 to 36 inches. The 10- to 40- inch control section averages from about 27 to 35 percent clay, with less than 15 percent sand coarser than very fine sand.
The A horizon has hue of 5YR or 7.5YR, value of 3 to 6, and chroma of 2 to 6. Where values are less than 3.5 the horizon is less than 8 inches thick. Texture is silt loam or silty clay loam.
The Bw horizon has hue of 5YR or 7.5YR, value of 4 to 6, and chroma of 3 to 6. Texture of the Bw horizon above the clayey horizon ranges from silt loam to silty clay loam with average clay content ranging from 20 to 30 percent. Thin horizontal stratification of coarser or finer texture varies from few to many with bedding planes.
The Ab horizon ranges from reddish brown to black, hue of 5YR to 10YR, value of 2 to 5, and chroma of 1 to 6. Texture of the Ab and Bb horizons ranges from silty clay loam to clay, with clay content of 35 to 50 percent, or about 10 to 20 percent more clay than the overlying silty C horizon. Reaction of the clayey Ab horizon ranges from neutral to moderately alkaline.
The Bb horizon ranges from reddish brown or brown to yellowish red.
COMPETING SERIES: This is the Norwood series. Similar soils are the Asa, Brazoria, Highbank, Ships, and Weswood series. Norwood soils do not have horizons containing more than 35 percent clay within 36 inches of the soil surface. Asa, Brazoria, Highbank, Ships, and Weswood soils are in the thermic temperature regime. In addition, Asa soils have a mollic epipedon. Brazoria and Ships soils are in the fine family. Highbank soils are in the fine family and have a cambic horizon.
GEOGRAPHIC SETTING: Clemville soils are on nearly level flood plains of rivers and other streams. Slopes are mainly less than 1 percent but range up to 3 percent. The soil formed in stratified, calcareous, silty and clayey alluvium. Mean annual precipitation ranges from 40 to 45 inches, and mean annual temperature ranges from 60 degrees to 70 degrees F. Thornthwaite annual P-E indices range from 56 to more than 68.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Asa, Brazoria, Norwood, and Pledger series. Asa, Brazoria, and Norwood soils are in similar positions. Pledger soils have a mollic epipedon, are clayey throughout, and have cracks when dry. They are in similar to slightly lower positions.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is slow. Runoff is low on slopes less than 1 percent, and medium on 1 to 3 percent slopes. Flooding occurs at intervals of once each 2 to 10 years, except where protected.
USE AND VEGETATION: Mainly used for cropland. Crops include cotton, corn, grain sorghums, and alfalfa. Native vegetation was a dense forest of pecan, cottonwood, elm, oak, and hackberry trees with an understory of coarse bunch grasses.
DISTRIBUTION AND EXTENT: Mainly along the lower Brazos and Colorado Rivers in Texas. The series is moderately extensive.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Wharton County, Texas, l975.
REMARKS: Classification change from Typic Udifluvents to Fluventic Eutrudepts (1998 and 2000) based on the presence of a weak cambic horizon evidenced by removal of carbonates, slight color change in the Bw horizon, and landscape position conducive to the development of a cambic horizon. Change from thermic to hyperthermic temperature regime based geographic distribution of the series.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 12 inches. (Ap and A horizons)
Cambic horizon - 12 to 30 inches. (Bw horizon)
Fluventic property - stratification and irregular decrease of organic carbon with depth.
ADDITIONAL DATA: Highway Department data on pedons sampled in Brazoria County, TX (S76TX-039-018) and Washington County, TX (S73TX-239-003).
TAXONOMIC VERSION: Soil Taxonomy, Second Edition, 1999.