LOCATION AGUST TX
Established Series
Rev. JLR/LEL
12/2010
AGUST SERIES
The Agust series consists of very deep, well drained, moderately rapidly permeable soils formed in loamy, mixed, gravelly sediments. These nearly level to moderately sloping soils on piedmont slopes, alluvial fans, and high terraces. Slopes range from 1 to 8 percent. Mean annual precipitation is about 12 inches and the mean annual air temperature is about 70 degrees F.
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, hyperthermic Ustic Haplocalcids
TYPICAL PEDON: Agust loamy fine sand--rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 7 inches; light brown (7.5YR 6/4) loamy fine sand, brown (7.5YR 4/4) moist; weak medium granular structure; slightly hard, very friable; few very fine and fine roots; 10 percent mixed-igneous and sedimentary gravel; strongly effervescent; moderately alkaline; clear smooth boundary. (3 to 10 inches thick)
Bk1--7 to 20 inches; light brown (7.5YR 6/4) gravelly sandy loam, brown (7.5YR 4/4) moist; weak medium subangular blocky structure; slightly hard, very friable; few very fine and fine roots; 25 percent mixed-igneous & sedimentary gravel; coarse fragments coated with calcium carbonate; coatings decrease with depth; strongly effervescent; moderately alkaline; clear smooth boundary.
Bk2--20 to 35 inches; brown (7.5YR 5/4) gravelly loamy sand, brown (7.5YR 4/4) moist; single grain; loose, very friable; 25 percent mixed-igneous and sedimentary gravel; 2 percent calcium carbonate coatings on coarse fragments; strongly effervescent; moderately alkaline; gradual smooth boundary. (Combined thickness of the Bk horizons is 20 to 35 inches.)
C--35 to 60 inches; light brown (7.5YR 6/4) gravelly fine sandy loam; brown (7.5YR 4/4) moist; single grain; loose, very friable; 20 percent mixed igneous & sedimentary gravel; strongly effervescent; moderately alkaline.
TYPE LOCATION: Brewster County, Texas; from the junction of U.S. Highway 67 and Texas Highway 118 in Alpine; 60.1 miles south on Texas Highway 118; 12.9 miles southeast on Terlingua Ranch Road; 0.6 miles east on Marathon Road; continue east 1.4 mile to gate to Sombrero Peak Ranch; 1.1 miles east; 1.0 mile south to ranch house; 100 yards south of house; 1.25 miles east on ranch road; 70 feet north of road in range. (Latitude: 29 degrees,29 minutes, 5.21 seconds North, Longitude: 103 degrees, 17 minutes, 22.89 seconds West. UTM 1983, Sombrero Peak Quadrangle.
RANGE IN CHARACTERISTICS:
Soil Moisture: Receives precipitation in all months. Driest period is November through April with peak rainfall occurring during May through October. Ustic aridic soil moisture regime.
Mean annual soil temperature: 72 to 78 degrees F.
Depth to calcic horizon: 6 to 30 inches
Clay content: 10 to 18 percent
Rock fragment content: 15 to 35 percent
A horizon
Hue: 7.5YR, 10YR
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 3 or 4, dry or moist
Clay content: 3 to 18 percent
Calcium carbonate equivalent: 5 to 10 percent
Rock fragment content: 5 to 35 percent mixed igneous and limestone fragments
Effervescence: slight to violent
Reaction: neutral to moderately alkaline
Bk horizons
Hue: 5YR, 7.5YR, 10YR
Value: 4 to 6 dry, 3 to 5 moist
Chroma: 3 or 4, dry or moist
Clay content: 3 to 18 percent
Calcium carbonate equivalent: 5 to 15 percent
Rock fragment content: 5 to 35 percent mixed igneous and limestone fragments
Effervescence: strong to violent
C horizons
Hue: 5YR, 7.5YR, 10YR
Value: 4 to 6 dry, 3 to 5 moist
Chroma: 3 to 4, dry or moist
Clay content: 3 to 18 percent
Calcium carbonate equivalent: 5 to 15 percent
Rock fragment content: 5 to 35 percent mixed igneous and limestone fragments
Effervescence: strong to violent
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Agust soils are on early Holocene age piedmont slopes, alluvial fans, and terraces. Slopes are dominantly about 3 percent, but range from 1 to 8 percent. The regolith consists of calcareous, gravelly-textured alluvium derived from igneous and sedimentary alluvium. Mean annual precipitation ranges from 10 to 13 inches, and the mean annual air temperature ranges from 68 to 76 degrees F. Frost-free period is 240 to 280 days, and elevation ranges from 1,965 to 3,935 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the
Equipaje,
Mariscal,
Ninepoint, and
Studybutte soils. These soils do not have calcic horizons.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately rapid. Runoff is negligible on slopes less than 3 percent, very low on 3 to 5 percent slopes, and low on 5 to 8 percent slopes.
USE AND VEGETATION: Used mostly for livestock grazing, wildlife habitat, and recreation. Vegetation consists of creosotebush, western honey, mesquite, tasajillo, and four-wing saltbush. Grasses include sand dropseed, fluffgrass, and six-weeks grama.
DISTRIBUTION AND EXTENT: In the western part of Trans-Pecos Texas and southern New Mexico. MLRA is 42. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Brewster County, Main Part, Texas; 2002
REMARKS:Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 7 inches (A horizon)
Calcic horizon - the zone from 7 to 20 inches (Bk horizon)
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Eleventh Edition, 2010.
Moisture and temperature regimes revised for TX622 - Brewster County recorrelation, 11/7/07, PDC.
Revised for the correlation of Big Bend National Park, TX, Oct. 2010, CEM
National Cooperative Soil Survey
U.S.A.