LOCATION DILLEY TXEstablished Series
TAXONOMIC CLASS: Loamy, mixed, active, hyperthermic, shallow Ustic Haplargids
TYPICAL PEDON: Dilley fine sandy loam--rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 8 inches; reddish brown (5YR 5/4) fine sandy loam, reddish brown (5YR 4/4) moist; weak fine subangular blocky structure; slightly hard, very friable; common fine roots; common fine pores; neutral; gradual wavy boundary. (4 to 12 inches thick)
Bt--8 to 13 inches; yellowish red (5YR 5/6) fine sandy loam, yellowish red (5YR 4/6) moist; compound weak medium prismatic and weak fine subangular blocky structure; hard, friable; common fine roots; many fine pores; clay bridges sand grains; neutral; clear wavy boundary. (4 to 14 inches thick)
Btk--13 to 16 inches; reddish yellow (7.5YR 6/6) sandy loam, strong brown (7.5YR 5/6) moist; weak fine subangular blocky structure; slightly hard, friable; clay bridges sand grains; estimated 25 percent by volume strong brown weakly cemented sandstone fragments that are thinly coated with calcium carbonate; sandstone fragments break down after overnight shaking in sodium hexametaphosphate; few fine concretions of calcium carbonate; calcareous; moderately alkaline; abrupt wavy boundary. (0 to 6 inches thick)
Crk--16 to 24 inches; strong brown (7.5YR 5/6) fractured weakly cemented sandstone bedrock with thin coatings of calcium carbonate on surfaces of cracks; horizontal spacing between cracks is more than 4 inches; thin seams of reddish yellow (7.5YR 6/6) fine sandy loam in cracks; few fine roots in cracks; noncalcareous;
TYPE LOCATION: Webb County, Texas; from the intersection of Interstate Highway 35 and U.S. Highway 59 in Laredo; 18.0 miles north on Interstate Highway 35 to junction with U.S. Highway 83; 20.0 miles northwest on U.S. 83 to the intersection with Texas Highway 44; 7.8 miles east on Texas 44; 500 feet north in rangeland.
RANGE IN CHARACTERISTICS: Soil depth ranges from 10 to 20 inches over sandstone bedrock. Reaction ranges from slightly acid to mildly alkaline. Coarse fragments of sandstone or chert range from 0 to 30 percent by volume in the sola or individual horizons.
The A horizon ranges from brown or light brown to reddish brown or reddish yellow in hue of 5YR through 7.5YR, value of 4 through 6, and chroma of 3 through 6. It is fine sandy loam or loamy fine sand. Coarse fragments of sandstone or siliceous pebbles and cobbles comprise 0 to 15 percent by volume.
The Bt horizon ranges from red or reddish brown to yellowish red or reddish yellow in hue of 2.5YR to 7.5YR, value of 4 through 6, and chroma of 4 through 6. It is fine sandy loam, sandy clay loam, or loam or their gravelly counterparts with a clay content of 12 to 25 percent.
The Cr layer is weakly cemented sandstone bedrock; The Cr layer in some pedons is interbedded with unconsolidated loamy and clayey sediments. The Cr layer can be dug with a spade when moist. The Cr may contain masses and strata of strongly cemented sandstone or ironstone.
COMPETING SERIES: There are no competing series in the same family. Series in similar families are Cuevitas, Delmita, Duval, Jimenez, Lacoste, Quemado, Randado, Sharvana, Verick, and Zapata series. Cuevitas, Delmita, Lacoste, Randado, and Sharvana soils have a petrocalcic horizon. In addition, Sharvana soils have soil temperatures less than 72 degrees F. Delmita and Duval soils have sola more 20 inches thick. Jimenez and Quemado soils have more than 35 percent coarse fragments in their sola, and in addition, Jimenez soils are calcareous. Verick soils have hue of 2.5Y and 10YR and are calcareous. Zapata soils are calcareous and lack an argillic horizon.
GEOGRAPHIC SETTING: Dilley soils are on nearly level to gently sloping uplands. Slopes range from 0 to 5 percent. The soil formed in loamy residuum over sandstone bedrock. Climate is semiarid. Mean annual precipitation ranges from 20 to 28 inches and mean annual air temperature ranges from 70 to 74 degrees F., Frost free days range from 250 to 320 days and elevation ranges from 450 to 800 feet. Thornthwaite annual P-E index range from 20 to about 33.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the similar Duval, Randado, and Zapata series and the Brystal, Goldfinch, Hindes, Miguel, Webb, and Yologo series. All of these soils are on similar surfaces. Brystal soils have sola more than 40 inches thick. Hindes, Miguel, and Webb soils have a clayey Bt horizon. Goldfinch, Hindes, and Yologo soils also have more than 35 percent coarse fragments in their sola.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability.
USE AND VEGETATION: Mainly rangeland, but some areas are farmed and most of these areas are irrigated. Peanuts, melons, grain sorghum, winter vegetables, and tame pasture are the main crops. Native vegetation consists of mid grasses, a few short grasses, about 5 percent woody shrubs and 10 percent perennial forbs. Typical forbs are velvet bundleflower, bushsunflower, and orange zexmania. As retrogression occurs, such mid grasses as tanglehead and silver bluestem decrease. Woody shrubs and short grasses increase or invade. Typical increasers and invaders are guajillo, blackbrush, leatherstem, hooded windmillgrass, sand dropseed, threeawn, and red grama.
DISTRIBUTION AND EXTENT: Northern and Western Rio Grande Plain of Texas. Series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Atascosa County, Texas; 1977.
REMARKS: Dilley soils were formerly classified as a shallow phase in Duval series.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 8 inches.
Argillic horizon - 8 to 16 inches.
Paralithic contact - at 16 inches.