LOCATION CASTROVILLE TXEstablished Series
TAXONOMIC CLASS: Fine-silty, carbonatic, hyperthermic Typic Calciustolls
TYPICAL PEDON: Castroville clay loam - cropland.
(Colors are for dry soil unless otherwise stated.)
Ap1--0 to 7 inches; grayish brown (10YR 5/2) dry silty clay loam; very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure parting to weak very
fine granular; slightly hard, friable; many very fine and fine roots; few fine tubular pores; Upper 2 mm of surface is a surface crust; few snail shell fragments; few medium, rounded, carbonate modules; 34 percent calcium carbonate equivalent; violently effervescent; mildly alkaline (ph=7.8); clear smooth boundary.
Ap2--7 to 16 inches; dark grayish brown (10YR 4/2) dry silty clay loam; very dark grayish brown (10YR 3/2) moist; weak coarse prismatic structure parting to moderate medium subangular blocky; hard, firm; common very fine and fine roots; few fine tubular pores; Common snail shell fragments; few medium, rounded, carbonate nodules; few threads and films of calcium carbonate; common earthworm Krotovinas to 5 mm in diameter; 39 percent calcium carbonate equivalent; violently effervescent; moderately alkaline (ph=8.0); clear wavy boundary.
Bk1--16 to 23 inches; yellowish brown (10YR 5/4) dry silty clay loam dark yellowish brown (10YR 4/4) moist; weak coarse prismatic structure parting to moderate fine and medium subangular blocky; hard, firm; common very fine and fine roots; common very fine and fine tubular pores; Common fine snail shell fragments; common films and threads of calcium carbonate; few earthworm Krotovinas to 5 mm in diameter; Krotovinas are metaaggrotubules; 42 percent calcium carbonate equivalent; violently effervescent; moderately alkaline (ph=8.0); gradual wavy boundary.
Bk2--23 to 32 inches; light brown (7.5YR 6/4) dry silty clay loam; brown to dark brown (7.5YR 4/4) moist; moderate fine subangular parting to moderate fine and medium subangular blocky; hard, friable; common very fine and fine roots; common very fine and fine tubular pores; Few snail shell fragments; about 3% by volume threads, films and medium rounded carbonate nodules; few earthworm Krotovinas to 5 mm in diameter; 49 percent calcium carbonate equivalent; violently effervescent; moderately alkaline (ph=8.0); gradual wavy boundary.
Bk3--32 to 55 inches; light brown (7.5YR 6/4) dry silty clay loam; brown to dark brown (7.5YR 5/4) moist; moderate fine subangular blocky structure; hard, friable; few very fine and fine roots; common fine and medium tubular pores; Few snail shell fragments; few waterworn limestone pebbles to 1 cm across about 5% by volume threads, films and soft masses of calcium carbonate, about 5% by volume medium to coarse rounded carbonate nodules; common earthworm Krotovinas; 51 percent calcium carbonate equivalent; violently effervescent; moderately alkaline (ph=8.0); gradual wavy boundary.
Bk4--55 to 76 inches; reddish yellow (7.5YR 6/6) dry silty clay loam; strong brown (7.5YR 5/6) moist; weak fine and medium subangular blocky structure; slightly hard, friable; few very fine and fine roots; few very fine and fine tubular pores; Few snail shell fragments; few medium rounded carbonate nodules, common films and threads of calcium carbonate; few waterworn limestone pebbles to 1 cm across; few earthworm Krotovinas to 5 mm in diameter; 52 percent calcium carbonate equivalent; violently effervescent; moderately alkaline (ph=8.2); gradual wavy boundary.
2Bk--76 to 82 inches; reddish yellow (7.5YR 6/6) dry silty clay; strong brown (7.5YR 5/6) moist; moderate fine and medium subangular blocky structure; slightly hard, friable; few very fine and fine roots; few very fine and fine tubular pores; about 3% by volume medium rounded carbonate nodules; 41 percent calcium carbonate equivalent; Few siliceous pebbles to 5 cm across mainly near upper boundary; pendants of calcium carbonate on lower sides of pebbles to 8 mm in thickness; few snail shell fragments; about 7% by volume threads, films and soft masses of calcium carbonate; violently effervescent; moderately alkaline (ph=8.1).
TYPE LOCATION: Medina County, Texas; from the intersection of U.S. Highway 90 and Texas Highway 173; east of Hondo, Texas; 3.3 miles north on Texas Highway 173; 225 feet west along fencline; 50 feet south in cropland.
RANGE IN CHARACTERISTICS: Solum thickness is more than 80 inches.
The A horizons have hue of 10YR, with value of 4 or 5, and chroma of 2 or 3. Texture is clay loam or silty clay loam.
The Bk horizons have hue of 10YR, with value of 5 to 7 , and chroma of 2 to 6. Texture is silty clay loam, clay, or silty clay. The 10 to 40 inch control section is 25 to 35 percent silicate clays and about 2 to 10 percent carbonate clays. Total carbonates in the control section exceed 40 percent and continue to increase with depth.
Gravel beds underlie some pedons below 6 feet.
COMPETING SERIES: There are no series in the same family. Similar soils include the Hidalgo, Knippa, Lewisville, Nuvalde, Set, Uvalde, Venus, and Yauco series. Atco and Karnes soils lack mollic epipedons. Lewisville, Knippa, Nuvalde, Set, and Venus soils have temperatures less than 72 degrees F. Hidalgo and Venus soils have control sections that have more than 15 percent sand coarser than very fine sand. Knippa soils have coefficient of linear extensibility values of 0.09 or greater. Uvalde soils are dry in the moisture control section for longer periods of time and have mixed mineralogy. Yauco soils have a mean annual soil temperature of more than 72 degrees F.
GEOGRAPHIC SETTING: Nearly level to gently sloping stream terraces on piedmont alluvial plains. Slope is generally less than 1 percent but ranges to 3 percent. The soil formed in alluvium from limestone formations and it is high in calcium carbonate. The climate is hot and dry subhumid. Mean annual temperature ranges from 69 to 70 degrees F. and mean annual precipitation is 26 to 32 inches. Thornthwaite annual P-E indices are 32 to 44. Frost free days range from 230 to 260 days and elevation ranges from 650 to 1250 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Atco, Conalb, Knippa, Mercedes, Montell, and Victoria series. Atco, Knippa, Mercedes, Montell, and Victoria soils occur on similar surfaces. Atco and Conalb soils lack mollic epipedons. Conalb soils occur at lower elevations on flood plains. Mercedes, Montell, and Victoria soils are clayey throughout.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate permeability.
USE AND VEGETATION: Used for cropland and rangeland. Cropland is used for growing mainly grain sorghum and small grain under dry farming operations and for these same crops in addition to corn, cotton, and truck crops under irrigation. Native grasses include red grama, threeawn, pink pappusgrass, bristlegrass, fall witchgrass, Texas wintergrass, Hall's panicum, and sand dropseed. Woody plants include mesquite, live oak, whitebrush, spiny hackberry, guayacan, Texas persimmon, twisted acacia, catclaw acacia, and lotebush condalia.
DISTRIBUTION AND EXTENT: Northern Rio Grande Plain of Texas. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Uvalde County, Texas; 1970.
REMARKS: They were formerly included in the Uvalde series.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 16 inches.
Cambic horizon - 16 to 32 inches.
Calcic horizon - 32 to 55 inches.
ADDITIONAL DATA: National Soil Survey Laboratory on type location: S86TX325-1 (86P1836-1842) and S86TX325-2 (86P1843-1844) S84TX325-1 (84P2423-2428)