LOCATION RUNN TXEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, hyperthermic Torrertic Haplustepts
TYPICAL PEDON: Runn silty clay--cultivated. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 8 inches; grayish brown (10YR 5/2) silty clay, dark grayish brown (10YR 4/2) moist; moderate medium granular structure; hard, firm; sticky and plastic; few roots, few fine pores; strongly effervescent; moderately alkaline; abrupt smooth boundary. (4 to 15 inches thick)
A--8 to 18 inches; grayish brown (10YR 5/2) silty clay, dark grayish brown (10YR 4/2) moist; weak fine and medium subangular blocky structure; hard, firm; sticky and plastic; few roots, few fine pores; few snail shell fragments; common wormcasts; strongly effervescent; moderately alkaline; clear smooth boundary. (6 to 20 inches thick)
Bk--18 to 38 inches; light brownish gray (10YR 6/2) silty clay, dark grayish brown (10YR 4/2) moist; moderate fine and medium subangular blocky structure; very hard, firm but crumbly; sticky and plastic; few fine pores; shiny pressure faces; few films and threads of calcium carbonate; violently effervescent; moderately alkaline; clear wavy boundary. (15 to 26 inches thick)
BCk--38 to 55 inches; pale brown (10YR 6/3) silty clay, brown (10YR 5/3) moist; massive; hard, firm; sticky and plastic; common fine pores; contains 3 percent concretions and masses of calcium carbonate; violently effervescent; moderately alkaline; diffuse wavy boundary. (12 to 22 inches thick)
2BCk--55 to 65 inches; pale brown (10YR 6/3) silty clay loam, brown (10YR 5/3) moist; massive; hard, firm; few thin strata of silt loam; few masses of calcium carbonate; violently effervescent; moderately alkaline.
TYPE LOCATION: Hidalgo County, Texas; in a cultivated field 0.2
mile north on Farm Road 336 from its junction with Farm Road
1016; 300 feet west and 350 feet north on field road; 100 feet
west of field road in field; junction is 3.0 miles south of Expressway and Farm Road 336 in McAllen, Texas.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 35 to 55 inches. Depth to strata of silt loam, silty clay, silty clay
loam, or very fine sandy loam ranges from 40 to 80 inches. These soils, when dry, have cracks 0.4 to 1.0 inch wide and 12 inches
or more long that extend to depths of 25 to 40 inches. COLE ranges from 0.07 to 0.17 throughout the solum. Soil salinity ranges from 1.0 to 4.0 dS/m in the surface layer and increases with depth. Salinity is 4 to 16 dS/m in some pedons that are irrigated.
The A horizon has hue of 7.5YR or 10YR, value of 5 or 6, and chroma of 2. Texture is a silty clay or silty clay loam.
The B horizon has hue of 7.5YR or 10YR, value of 5 or 6, and chroma of 5 or 6. Texture is silty clay or silty clay loam.
The BC horizon has hue of 7.5YR or 10YR, value of 6 or 7, and chroma of 2 to 4. Texture is silty clay, silty clay loam, or silt loam. Calcium carbonate equivalent is 3 to 5 percent and remains relatively constant with depth.
COMPETING SERIES: These are the Viboras series. Similar soils are the Cameron, Chargo, Harlingen, Olmito, and Reynosa series. Cameron and Olmito soils have a mollic epipedon. Chargo soils have massive and hardsetting epipedons. Harlingen soils have slickensides within 40 inches. Reynosa soils are in the fine-silty family.
GEOGRAPHIC SETTING: Runn soils are on nearly level low terraces above most overflows. Surfaces are plane to weakly concave with slopes mainly less than 1 percent. The soil formed in stratified alluvial calcareous silty sediments many feet thick. Mean annual precipitation ranges from 17 to 27 inches, mean annual temperature ranges from 74 to 76 degrees F., and Thornthwaite P-E indices range from 21 to 32.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing Harlingen and Reynosa series that occur on similar surfaces.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow runoff and slow internal drainage; slow permeability. A seasonal water table at depths of 4 to 8 feet occurs in some irrigated areas.
USE AND VEGETATION: Mostly cultivated and irrigated. Crops grown are cotton, grain sorghum, and a wide variety of cool season vegetables. Native vegetation was midgrasses and thorny shrubs.
DISTRIBUTION AND EXTENT: Occurs principally on old flood plains
in southern Rio Grande Plain of Texas and probably in Mexico. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Hidalgo County, Texas; 1979.
REMARKS: Diagnositic horizons and features recognized in this pedon are:
Ochric epipedon: 0 to 18 inches. (A horizons)