LOCATION ASA TX+OKEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, hyperthermic Fluventic Hapludolls
TYPICAL PEDON: Asa silty clay loam--cropland. (Colors are for moist soil unless otherwise stated.)
Ap--0 to 6 inches; black (5YR 2.5/1) silty clay loam, dark reddish gray (5YR 4/2) dry; moderate fine and medium subangular blocky structure; hard, firm; many very fine and fine roots, few medium roots; few fine pores; few worm casts, neutral; clear smooth boundary. (4 to 8 inches thick)
A--6 to 14 inches; black (10YR 2/1) silty clay loam, very dark gray (10YR 3/1) dry; moderate coarse prismatic structure parting to moderate medium subangular blocky; hard, firm; few very fine and fine roots; few fine pores; about 5 percent vertically oriented worm holes about 1/8 inch across filled with brown worm casts; neutral; clear smooth boundary. (6 to 12 inches thick)
B/A--14 to 19 inches; brown (7.5YR 4/4) silty clay loam, pink (7.5YR 7/4) dry, dark brown (7.5YR 3/2) (40 percent A); weak coarse prismatic structure parting to moderate medium subangular blocky; hard, firm; few fine roots; common very fine and fine pores; about 5 percent vertically oriented worm holes about 1/4 inch across filled with black or brown worm casts; common very fine mica flakes; strongly effervescent; moderately alkaline; clear smooth boundary. (0 to 10 inches thick)
Bw1--19 to 27 inches; brown (7.5YR 4/4) silty clay loam, pink (7.5YR 7/4) dry; about 15 percent by volume dark brown (7.5YR 3/2) A material; weak coarse prismatic structure parting to moderate medium and fine subangular blocky; hard, friable; few fine roots; common fine and medium pores; about 2 percent fine pitted calcium carbonate nodules; about 5 percent vertically oriented worm holes about 1/4 inch across filled with black worm casts; few very fine mica flakes; violently effervescent; moderately alkaline; clear smooth boundary.
Bw2--27 to 33 inches; brown (7.5YR 4/4) silty clay loam; pink (7.5YR 7/4) dry; weak coarse prismatic structure parting to moderate medium and fine subangular blocky; hard, friable; few fine roots; many very fine and fine pores; about 2 percent fine pitted calcium carbonate nodules; about 5 percent dark brown material on faces of prisms; about 5 percent vertically oriented worm holes about 1/4 inch across filled with black worm casts; few very fine mica flakes; violently effervescent; moderately alkaline; clear smooth boundary. (combined thickness of the Bw horizon is 10 to 60 inches)
Bk--33 to 38 inches; brown (7.5YR 4/4) silty clay loam, pink (7.5YR 7/4) dry; few fine prominent reddish brown (2.5YR 4/4) and few fine distinct yellowish red (5YR 4/6) redox concentrations; weak coarse prismatic structure parting to moderate medium subangular blocky; hard, friable; few fine roots; few very fine and fine pores; about 5 percent medium pitted calcium carbonate nodules; few films, threads and masses of calcium carbonate; about 5 percent worm holes about 1/2 inch across filled with black worm casts; violently effervescent; moderately alkaline; abrupt smooth boundary. (0 to 20 inches thick)
B'w1--38 to 49 inches; brown (7.5YR 4/4) and reddish brown (5YR 4/3) silt loam, pink (7.5YR 7/4) dry; common fine and medium faint brown (7.5YR 5/4) redox concentrations; moderate coarse prismatic structure parting to weak fine angular blocky; hard, friable; few fine roots; many fine and medium pores; 2 percent medium and coarse pitted calcium carbonate nodules; few brown very thin coatings on faces of prisms; about 5 percent worm holes 1/2 inch across filled with very dark gray worm casts; common very fine mica flakes; few fine snail shells fragments; violently effervescent; moderately alkaline; abrupt smooth boundary.
B'w2--49 to 61 inches; reddish brown (5YR 4/4) silt loam, reddish yellow (7.5 6/6) dry; moderate coarse prismatic structure parting to weak fine subangular blocky; hard, friable; few fine roots; many very fine and few fine and medium pores; few coarse pitted calcium carbonate nodules; few brown and red very thin coatings on faces of prisms; about 5 percent vertically oriented worm holes 1/4 inch across filled with black worm casts; few very fine mica flakes; violently effervescent; moderately alkaline; clear smooth boundary.
B'w3--61 to 71 inches; brown (7.5YR 5/4) silt loam, pink (7.5YR 4/4) dry; few fine faint strong brown (7.5YR 5/6) redox concentrations; weak coarse prismatic structure parting to weak fine angular blocky; hard, friable; few fine roots; many fine pores; about 2 percent medium pitted calcium carbonate nodules; common fine and medium brown coatings along root channels; about 3 percent vertically oriented worm holes 1/4 inch across filled with black worm casts; few very fine mica flakes; violently effervescent; moderately alkaline; clear smooth boundary.
B'w4--71 to 80 inches; reddish brown (5YR 4/4) silty clay loam, light brown (7.5YR 6/4) dry; few fine faint reddish brown (5YR 5/4) redox concentrations; weak coarse prismatic structure parting to weak fine angular blocky; hard, firm; few fine roots; common fine pores; few coarse pitted calcium carbonate nodules; about 3 percent vertically oriented worm holes about 1/4 inch across filled with black worm casts; violently effervescent; moderately alkaline; abrupt smooth boundary. (combined thickness of the B'w horizon is 0 to 60 inches)
TYPE LOCATION: Wharton County, Texas; from the intersection of U.S. Highway 59 and Texas Highway 60 north of Wharton, 0.8 mile south on Texas Highway 60, 0.25 mile west on County Road 222, and 195 feet south in cropland. (Latitude: 29N, 21, 23; Longitude: 96W, 05, 45)
RANGE IN CHARACTERISTICS: The solum is more than 80 inches thick. The A and upper B horizons of most pedons contain 20 to 40 percent wormcasts. The particle-size control section has 18 to 35 percent clay, more than 40 percent silt, and less than 15 percent fine sand and coarser sand. Organic-carbon content decreases irregularly between a depth of 10 and 50 inches. Also, organic-carbon content ranges from 0.3 to 0.5 at a depth of 50 inches. Redox concentrations in shades of red and brown range from none to common throughout the cambic horizon. Some pedons near the coast range from slightly to strongly saline because of saltwater intrusion during storms.
The A horizon has colors with hue of 5YR to 10YR, value of 2 or 3, and chroma of 1 to 3. Texture is silt loam or silty clay loam. Reaction is neutral to moderately alkaline.
A transitional B/A horizon is present in most pedons. It has colors the same as the A and Bw horizons. Reaction is slightly alkaline or moderately alkaline and is slightly effervescent in some pedons.
The Bw and B'w horizons have colors with hue of 5YR to 10YR, value of 4 to 6, and chroma of 3 to 8. Texture is very fine sandy loam, loam, silt loam, or silty clay loam. The reaction is moderately alkaline and the matrix is strongly to violently effervescent.
The Bk horizon has colors with hue of 5YR to 10YR, value of 4 to 6, and chroma of 3 to 8. The Bk horizon contains about 5 to 10 percent visible calcium carbonate in the form of films, threads, masses, and pitted nodules. Some pedons have a calcic horizon.
Some pedons have a buried A horizon at a depth of 60 to 80 inches.
COMPETING SERIES: There are no other series in the same family. Similar soils are the Clemville, Norwood, and Weswood series. Clemville, Norwood, and Weswood soils have ochric epipedons. In addition, Weswood soils are in the ustic moisture regime.
GEOGRAPHIC SETTING: Asa soils are on flood plains of the lower Colorado and Brazos Rivers. The soils formed in calcareous, reddish, stratified loamy alluvium derived mainly from Permian redbed sediments. These soils are rarely flooded or occasionally flooded for very brief to brief periods. Slopes are plain to convex and dominantly less than 1 percent, but range to 3 percent. The mean annual precipitation ranges from 40 to 52 inches. The mean annual temperature ranges from 70 degrees to 72 degrees F. The frost free period is from 265 to 280 days. Elevation ranges from 3 to 150 feet above sea level. The annual Thornthwaite P-E indices range from about 56 to 70.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Clemville and Norwood, and the Brazoria and Pledger series. Clemville and Norwood soils are on similar positions. Brazoria and Pledger soils are clayey throughout and are in slightly lower positions on the floodplain.
DRAINAGE AND PERMEABILITY: Well drained; runoff is negligible on slopes of less than 1 percent and very low on slopes of 1 to 3 percent; moderately permeable.
USE AND VEGETATION: Used mainly for cropland. The major crops are cotton, corn, sorghums, and truck crops. Native vegetation is Virginia wildrye, big bluestem, indiangrass, little bluestem, switchgrass, eastern gammagrass, sedges, low panicum, and perennial forbs. Trees are mainly pecan, elm, and hackberry.
DISTRIBUTION AND EXTENT: On flood plains of the lower Brazos and Colorado Rivers in the Coast Prairie area of Texas, (MLRA 150A, 150B). The series is extensive with more than 110,000 acres correlated.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: McLennan County, Texas; 1941.
REMARKS: The classification of the series was changed from thermic Fluventic Haplustolls to hyperthermic Fluventic Hapludolls 1/93 based on geographic distrubution of the series.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 14 inches (Ap and A horizons).
Cambic horizon - 14 to 80 inches (B horizons).
Fluventic feature - irregular decrease of organic carbon between 10 and 50 inches. B'w1 and B'w2 horizons contain 0.5 and 0.3 organic carbon respectively.
ADDITIONAL DATA: TAMU characterization data from type location in Wharton County, TX (S92TX-481-001). SDHPT data from Washington County, TX (S73TX-239-004) and Brazoria County, TX (S76TX-039-019).