LOCATION BOBILLO TXEstablished Series
TAXONOMIC CLASS: Loamy, siliceous, active, hyperthermic Grossarenic Paleustalfs
TYPICAL PEDON: Bobillo sand, on a 1 percent slope in rangeland. (Colors are for dry soil unless otherwise stated.)
A1--0 to 30 inches; light yellowish brown (10YR 6/4) sand, dark yellowish brown (10YR 4/4) moist; single grained; loose, very friable; common fine roots; slightly acid; gradual smooth boundary. (8 to 30 inches thick)
A2--30 to 48 inches; very pale brown (10YR 7/4) sand, yellowish brown (10YR 5/4) moist; single grained; loose, very friable; few fine roots; slightly acid; clear wavy boundary. (12 to 30 inches thick)
E--48 to 58 inches; very pale brown (10YR 8/3) sand, pale brown (10YR 6/3) moist; few fine faint mottles of white (10YR 8/2) and yellow (10YR 7/6); single grained; loose, very friable; few fine roots; slightly acid; abrupt wavy boundary. (6 to 24 inches thick)
Bt1--58 to 72 inches; very pale brown (10YR 7/3) sandy clay loam, pale brown (10YR 6/3) moist; common, fine and coarse, distinct mottles of reddish yellow (7.5YR 6/6), few fine faint mottles of light brownish gray (10YR 6/2); moderate, medium columnar structure parting to weak subangular blocky; very hard, friable, few fine pores; patchy clay films; medium acid; gradual wavy boundary. (4 to 16 inches thick)
Bt2--72 to 80 inches; pale yellow (5Y 7/3) sandy clay loam, pale yellow (5Y 7/3) moist; common fine and coarse prominent mottles of reddish yellow (5YR 6/6), yellowish red (5YR 5/6), and red (2.5YR 4/6), and few fine faint mottles of white; weak subangular blocky structure; very hard, friable; patchy clay films; slightly acid.
TYPE LOCATION: Dimmit County, Texas; 1.7 miles south of Carrizo Springs on Farm Road 186, 1.6 miles south on Farm Road 2368, 0.7 mile west on dirt road, 100 feet south in rangeland.
RANGE IN CHARACTERISTICS: Solum thickness is 80 to 100 inches or more. Thickness to the Bt horizon is 40 to 80 inches. Reaction ranges from medium acid to mildly alkaline throughout.
The A horizon has hue of 10YR or 7.5YR, value of 5 to 7, and chroma of 2 to 4. It is sand, fine sand, loamy sand, or loamy fine sand.
The E horizon has hue of 10YR or 7.5YR, value of 6 to 8, and chroma of 2 to 4. It has none to common, fine, faint to distinct light brownish gray, light gray, white, yellowish brown, brownish yellow, and yellow mottles. It is sand, fine sand, loamy sand, or loamy fine sand.
The Bt horizon has hue of 10YR or 2.5Y, value of 6 to 8, and chroma of 2 to 6. It has common to many, faint to prominent mottles in varying shades of brown, red, and gray. It is sandy clay loam or fine sandy loam with 15 to 32 percent clay content. Few to common fragments of sandstone occur in some pedons below 60 inches.
A Cr horizon of sandstone occurs in some pedons below 80 inches.
COMPETING SERIES: There are no soils in the same family. Similar soils include Aluf, Catilla, Coving, Desan, Hitilo, Nueces, Padina, Patilo, Sarita, Silvern, and Vernia series. Aluf soils have sandy control sections with Bt horizons composed of lamella. Catilla, Coving, Desan, Padina, Patilo, Silvern, and Vernia soils have annual average soil temperatures less than 72 degrees F. In addition, Coving soils have grayish mottles within 30 inches of the surface, and Silvern soils have more than 35 percent coarse fragments in their control sections. Hitilo, Nueces, and Sarita soils are moist in the moisture control section for longer periods. In addition, Nueces soils have grayish mottles within 30 inches of the surface and A horizons less than 40 inches thick. Vernia soils have more than 35 percent coarse fragments in their control sections.
GEOGRAPHIC SETTING: Bobillo soils occur in nearly level to gently undulating uplands. The surface is plain to hummocky, with slopes of 0 to 5 percent. The soil developed in sandy sediments in areas of the Carrizo Sand geologic formation. The surface has been somewhat reworked by wind. The climate is semiarid or dry subhumid. Mean annual precipitation ranges from 18 to 24 inches and mean annual temperature ranges from 70 to 72 degrees F. Frost free days range from 260 to 290 days and elevation ranges from 500 to 950 feet. Thornthwaite annual P-E indices range from 25 to 31.
GEOGRAPHICALLY ASSOCIATED SOILS: These include Aluf, Antosa, Brystal, Duval, Hitilo, Tonio, and Webb series. All these soils, except for Aluf and Hitilo soils, have epipedons less than 40 inches thick. Aluf and Hitilo soils occur at slightly higher elevations. Aluf soils have lamellae in the Bt horizon and Hitilo soils are more acid. All other soils occur at slightly lower elevations. In addition, Tonio soils are calcareous and Webb soils have more than 35 percent clay in the upper 20 inches of the Bt horizon.
DRAINAGE AND PERMEABILITY: Well drained; very slow runoff; moderate permeability.
USE AND VEGETATION: Used mostly for range. In excellent condition, vegetation is dominated by seacoast bluestem with scattered motts of live oak and bumelia. With retrogression, the principal plants which increase or invade are balsamscale, threeawn, fringed signalgrass, grassbur, mesquite, pricklypear, tephrosia, beebalm, and a wide variety of weedy forbs.
DISTRIBUTION AND EXTENT: Northern and Western Rio Grande Plain of Texas. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Dimmit County, Texas; 1982.
REMARKS: Bobillo series was formerly included in the Sarita series.
Diagnostic horizons and features recognized in this pedon are:
Ochric (Grossarenic) epipedon - 0 to 58 inches. (A1, A2 and E horizons)
Albic horizon (E horizon).
Argillic horizon - 58 to 80 inches. (Bt1 and Bt2 horizons)
Aquic feature - white mottles in E horizon - 48 to 58 inches.