LOCATION BASTROP TX+OKEstablished Series
The Bastrop series consists of very deep, well drained, moderately permeable soils formed in loamy alluvium. These soils are on nearly level to moderately sloping stream terraces. Slopes range from 0 to 8 percent.
TAXONOMIC CLASS: Fine-loamy, mixed, active, thermic Udic Paleustalfs
TYPICAL PEDON: Bastrop fine sandy loam--cultivated. (Colors are for dry soil unless otherwise stated).
A1--0 to 10 inches; brown (7.5YR 5/4) fine sandy loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; slightly hard, friable; many fine and common medium roots; common very fine pores; few medium rounded siliceous pebbles; slightly acid; abrupt smooth boundary. (4 to 18 inches thick)
A2--10 to 13 inches; reddish brown (5YR 5/4) fine sandy loam, reddish brown (5YR 4/4) moist; weak medium and fine subangular blocky structure; slightly hard, friable; many fine and few medium roots; common very fine pores; few mole burrows up to 2-1/2 inches in diameter; few fine wormcasts; few medium rounded siliceous pebbles; slightly acid; clear wavy boundary. (0 to 6 inches thick)
Bt1--13 to 20 inches; reddish brown (5YR 4/4) sandy clay loam, reddish brown (5YR 4/4) moist; strong coarse prismatic and moderate medium subangular blocky structure; hard, friable; many fine and few medium roots; many very fine pores; common thin patchy clay films on surfaces of peds; many fine wormcasts; few worm nests and holes filled with slightly darker soil; few medium rounded siliceous pebbles; neutral; gradual wavy boundary. (4 to 20 inches thick)
Bt2--20 to 30 inches; yellowish red (5YR 4/6) sandy clay loam, yellowish red (5YR 4/6) moist; strong coarse prismatic and moderate medium subangular blocky structure; hard, firm; many fine roots; few medium roots; many very fine and fine pores; common thin dark reddish brown (5YR 3/4) clay films on surfaces of prisms; many fine wormcasts; few krotovinas as much as 0.5 inch in diameter; few medium rounded siliceous pebbles; neutral; gradual wavy boundary. (8 to 30 inches thick)
Bt3--30 to 50 inches; yellowish red (5YR 4/6) sandy clay loam, yellowish red (5YR 4/6) moist; strong coarse prismatic and moderate medium subangular blocky structure; hard, firm; common fine and few medium roots; many very fine and fine pores; common thin reddish brown (5YR 4/4) clay films on surfaces of prisms; many fine and very fine wormcasts; few medium rounded siliceous pebbles; neutral; gradual wavy boundary. (10 to 30 inches thick)
Bt4--50 to 72 inches; yellowish red (5YR 5/6) sandy clay loam, yellowish red (5YR 4/6) moist; moderate coarse prismatic and moderate medium and coarse subangular blocky structure; hard, firm; few fine roots; many very fine and few fine pores; common thin clay films on surfaces of prisms; common fine wormcasts; few medium rounded and angular siliceous pebbles; neutral; clear wavy boundary. (0 to 30 inches thick)
BCtk--72 to 80 inches; yellowish red (5YR 5/8) sandy clay loam, yellowish red (5YR 4/6) moist; weak coarse prismatic and moderate medium and coarse subangular blocky structure; hard, friable; few fine roots; common very fine and fine pores; few very fine wormcasts; few patchy clay films on surfaces of prisms; few medium rounded siliceous pebbles and few fragments of calcareous sandstone; few films and threads of calcium carbonate on surfaces of prisms; strongly effervescent; neutral.
TYPE LOCATION: Palo Pinto County, Texas south of Mineral Wells; from the intersection of Interstate Highway 20 and U.S. Highway 281, north on U.S. Highway 281 to the west end of the Brazos River bridge, and 0.8 mile north-northeast on U.S. Highway 281; site is west of the highway and 60 feet from a fence.
RANGE IN CHARACTERISTICS: Solum thickness is 60 to more than 80 inches. Small siliceous pebbles range from none to about 3 percent by volume throughout. The clay content of the control section ranges from 20 to 35 percent.
The A horizon has hue of 5YR to 10YR, value of 4 to 6, and chroma of 2 to 6. Texture is loamy fine sand, fine sandy loam, very fine sandy loam, or loam. Reaction ranges from moderately acid to slightly alkaline.
The Bt horizons have hue of 2.5YR to 7.5YR, value of 4 to 6, and chroma of 4 to 8. Texture is loam, sandy clay loam, or clay loam with clay content of about 20 to 35 percent. Reaction ranges from moderately acid to moderately alkaline. Most pedons are calcareous below 60 inches.
The BC or BCtkhorizon, where present, has hue of 5YR to 7.5YR, value of 5 to 7, and chroma of 4 to 8. This horizon is sandy clay loam, loam, or clay loam with or without strata of fine sandy loam or loamy sand. Some pedons have secondary calcium carbonate in the form of films, threads, and concretions below 60 inches. Some pedons have gravelly layers below 60 inches and most pedons have gravelly layers within a depth of 12 feet.
COMPETING SERIES: There are no competing series in the same family. Similar soils are the Delwin, Duffau, Galey, Grandfield, Konowa, May, Miles, Pedernales, and Travis series. Delwin and Miles soils are dry for longer periods of time (Typic). Duffau soils have siliceous mineralogy. Galey soils are moderately acid or strongly acid throughout the Bt horizon. Grandfield, Konowa, and May soils have argillic horizons with a significant decrease in clay from the maximum within 60 inches of the surface (Hapl). Pedernales and Travis soils are in the fine family.
GEOGRAPHIC SETTING: Bastrop soils are on nearly level to undulating stream terraces. Surfaces are plane to convex, and slopes range from 0 to 8 percent, but are dominantly less than 3 percent. The soil formed in thick reddish beds of loamy alluvium. Mean annual precipitation ranges from 28 to 40 inches, and mean annual temperature ranges from 64 to 70 degrees F. Frost-free days range from 220 to 270 days, and elevation ranges from 400 to 1,200 feet. Thornthwaite P-E indices range from 40 to 56.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Asa, Axtell, Dougherty, Pedernales, and Travis series. Asa soils have a mollic epipedon and are on lower terraces positions. Axtell soils have a clayey control section, and are on higher terrace remnants in upland positions. Dougherty soils have a loamy fine sand A horizon more than 20 inches thick, and are on lower terraces positions.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate. Runoff is negligible on slopes less than 1 percent, very low on 1 to 3 percent slopes, low on 3 to 5 percent slopes, and medium on 5 to 8 percent slopes.
USE AND VEGETATION: About half of Bastrop soils are cultivated to cotton, corn, grain sorghums, tree fruits, peanuts, and vegetables. The remainder is planted in johnsongrass, sudan, bermudagrass, and oats, and is used as pastureland and hayland.
DISTRIBUTION AND EXTENT: Central and southeast Texas mainly along the Colorado and Brazos Rivers. Series is of large extent.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Bastrop County, Texas; 1907.
REMARKS: Active cation exchange activity class. Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 13 inches. (A horizons)
Argillic horizon - 13 to 80 inches. (Bt horizons)
Pale feature - Soil does not have a 20 percent decrease in clay content within a depth of 60 inches, and has a chroma of 6 at 60 inches.