LOCATION DUVAL TXEstablished Series
TAXONOMIC CLASS: Fine-loamy, siliceous, active, hyperthermic Aridic Haplustalfs
TYPICAL PEDON: Duval very fine sandy loam--cultivated. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 7 inches; yellowish red (5YR 4/6) very fine sandy loam, dark reddish brown (5YR 3/4) moist; weak fine subangular blocky structure; hard, very friable; few fine roots; few slightly browner streaks and pockets of slightly sandier material; slightly sandier than horizon below probably due to winnowings; slightly acid; abrupt smooth boundary. (4 to 8 inches thick)
A--7 to 16 inches; yellowish red (5YR 4/6) very fine sandy loam, dark reddish brown (5YR 3/4) moist; weak fine and medium subangular blocky structure; hard, very friable; few fine pores and old root channels; few slightly browner streaks and pockets of slightly sandier material; slightly acid; clear smooth boundary. (4 to 14 inches thick)
Bt1--16 to 22 inches; yellowish red (5YR 4/6) sandy clay loam, dark reddish brown (5YR 3/4) moist; weak medium prismatic structure, parting to weak fine and medium subangular blocky; hard, friable; few fine roots; few fine pores and old root channels; few patchy clay films; clay films between sand grains; few krotovina; neutral; gradual wavy boundary. (4 to 22 inches thick)
Bt2--22 to 34 inches; red (2.5YR 4/6) sandy clay loam, dark red (2.5YR 3/6) moist; weak medium prismatic structure, parting to weak fine and medium subangular blocky; hard, friable; few fine roots; few fine pores and old root channels; few patchy clay films; clay films between sand grains; few krotovina; few sandstone fragments 2 mm to 13 mm in diameter; few ironstone fragments 2 mm to 7 mm in diameter; mildly alkaline; gradual wavy boundary. (4 to 26 inches thick)
Bt3--34 to 44 inches; red (2.5YR 4/8) sandy clay loam, dark red (2.5YR 3/6) moist; weak medium prismatic structure, parting to weak fine and medium subangular blocky; hard, friable; very few fine roots; few fine pores and old root channels; few patchy clay films; clay films between sand grains; few krotovina; few weakly cemented sandstone fragments 2 mm to 13 mm in diameter; few ironstone fragments 2 mm to 7 mm in diameter; mildly alkaline; gradual wavy boundary. (6 to 22 inches thick)
Bt4--44 to 52 inches; yellowish red (5YR 5/6) sandy clay loam; yellowish red (5YR 4/6) moist; weak fine subangular blocky structure; hard, friable; contains about 15 percent by volume of weakly cemented sandstone fragments 2 mm to 25 mm in size; few soft masses and concretions of calcium carbonate in the lower part; few ironstone fragments 2 mm to 7 mm in size; clay films between sand grains; moderately alkaline; abrupt wavy boundary. (3 to 18 inches thick)
2Crk--52 to 72 inches; white (10YR 8/1) weakly cemented sandstone bedrock, light gray (10YR 7/1) moist; common, fine and medium, distinct mottles of yellowish brown, strong brown, reddish yellow and yellowish red; weakly cemented but extractable with hand auger; contains about 5 percent yellowish red sandy clay loam in upper part; common thin seams and small pockets of calcium carbonate; sandstone is noncalcareous; moderately alkaline.
TYPE LOCATION: Frio County, Texas; from the intersection of Farm Road 140 and U.S. Highway 81 in Pearsall, 1.3 miles west on Farm Road 140; 14.3 miles south on IH-35 (Dilley exit); 1.0 mile north on access road; 300 feet west of right-of-way on farm road; 125 feet south in irrigated cropland.
RANGE IN CHARACTERISTICS: Soil depth ranges from 40 to 60 inches over sandstone bedrock. Secondary calcium carbonate is at depths below 35 inches. Siliceous pebbles and fragments of sandstone comprise 0 to 15 percent of the surface and control section and 0 to 25 percent of the B3 horizon. Sandstone fragments may occur as pebble or cobble bands in the B horizons of some pedons.
The A horizon ranges from brown or reddish brown to light brown or yellowish red in hue of 10YR, 7.5YR, and 5YR with value of 4 through 6, and chroma of 2 through 8. Texture is fine sandy loam or very fine sandy loam to loamy fine sand. It is slightly acid or neutral.
The Bt horizon ranges from red or reddish brown to yellowish red or reddish yellow in hue of 7.5YR, 5YR, or 2.5YR with value of 4 through 7, and chroma of 3 through 8. The zone of maximum clay accumulation is of reddish color. Texture ranges from very fine sandy loam or fine sandy loam to sandy clay loam with average clay content of 18 to 34 percent. It is slightly acid to mildly alkaline in the upper part and slightly acid to moderately alkaline in the lower part.
The Bt4 horizon has colors that are 1 or 2 units higher in value and chroma. It is slightly acid to moderately alkaline.
The Cr horizon is weakly to moderately cemented sandstone bedrock or soft sandstone bedrock that slakes in water. Some pedons have Cr/C horizons of sandstone bedrock interbedded with reddish to yellowish sandy clay loam, very fine sandy loam, fine sandy loam or soft siltstone. Some Cr horizons contain strata and masses of strongly cemented sandstone or ironstone. The soil may have a weakly to moderately expressed Crk horizon.
COMPETING SERIES: These include the similar Brennan, Brystal, Comitas, Hebbronville, Menard, and Rochelle series. Brennan and Brystal soils have secondary calcium carbonate at depths of less than 36 inches and mixed mineralogy. Comitas soils have sandy epipedons more than 20 inches thick. Hebbronville soils have less than 18 percent clay in the upper 20 inches of the Bt horizon. Menard and Rochelle soils have mean annual soil temperatures less than 72 degrees F, and are moist in the moisture control section for longer periods.
GEOGRAPHIC SETTING: Duval soils are on nearly level to gently sloping upland plains. Slope gradients range from 0 to 5 percent. The soil formed in loamy residuum from interbedded sandstone and siltstone over sandstone bedrock. Mean annual precipitation ranges from 20 to 28 inches and mean annual air temperature ranges from 69 to 74 degrees F., Frost free days range from 240 to 320 days and elevation ranges from 450 to 800 feet. Thornthwaite annual P-E index ranges from 23 to 36.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Brennan, Brystal, and Comitas series; Delmita, Dilley, Floresville, Poth, and Webb series. All these soils occur on similar positions. Delmita soils have petrocalcic horizons at depths of less than 40 inches. Floresville, Poth, and Webb soils have clayey Bt horizons.
DRAINAGE AND PERMEABILITY: Well drained; runoff is negligible to low; permeability is moderate.
USE AND VEGETATION: Mostly rangeland, but large areas are dry farmed and others are irrigated to peanuts, melons, cotton, grain sorghum, vegetables, and tame pastures. The original plant community was open grassland, dominated by mid-grasses with scattered shrubs, a few short grasses and about 5 percent perennial forbs. With retrogression, typical increasers and invaders are mesquite, spiny hackberry, pricklypear, hooded windmillgrass, threeawn, Hall's panicum, red lovegrass, fringed signalgrass, grassbur and annual forbs.
DISTRIBUTION AND EXTENT: Northern and Western Rio Grande Plain of Texas. The series is of large extent, with a total acreage in excess of 500,000 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Reconnaissance soil survey of South Texas, Duval County; 1909.
REMARKS: This series was formerly included in the Reddish Chestnut great soil group.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 16 inches.
Argillic horizon - 16 to 52 inches.
Paralithic contact at 52 inches.
ADDITIONAL DATA: National Soil Survey Laboratory data on type location, S79TX163-1 (79D1717-1720).