LOCATION EQUIPAJE TXEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, hyperthermic Ustic Haplocambids
TYPICAL PEDON: Equipaje fine sandy loam- rangeland. (colors are for dry soil unless otherwise noted.)
A--0 to 2 inches; light yellowish brown (10YR 6/4) fine sandy loam, brown (10YR 4/3), moist; loose, very friable; weak medium platy structure; few very fine roots; 1 percent subrounded igneous gravel; strongly effervescent; moderately alkaline; clear smooth boundary. (1 to 5 inches thick)
Bw1--2 to 5 inches; brown (10YR 5/3) fine sandy loam, brown (10YR 4/3), moist; weak coarse and medium subangular blocky structure; soft, very friable; many very fine roots, common fine roots, and few medium roots; 1 percent discontinuous distinct very pale brown (10YR 8/2) carbonate coats on rock fragments; 1 percent subrounded igneous gravel; strongly effervescent; moderately alkaline; clear smooth boundary.
Bw2--5 to 18 inches; light yellowish brown (10YR 6/4) fine sandy loam, dark yellowish brown (10YR 4/4), moist; weak coarse subangular blocky parting to weak medium subangular blocky parting to weak fine subangular blocky structure; soft, very friable; many very fine roots and common fine roots; 1 percent continuous distinct very pale brown (10YR 8/2), dry, carbonate coats on rock fragments; 2 percent subrounded igneous gravel; strongly effervescent; moderately alkaline; clear smooth boundary.
Bw3--18 to 26 inches; light yellowish brown (10YR 6/4) fine sandy loam, yellowish brown (10YR 5/4), moist; weak coarse and medium subangular blocky structure; soft, very friable; many very fine and common fine roots; 60 percent continuous distinct very pale brown (10YR 8/2), dry, carbonate coats on rock fragments; 8 percent subrounded igneous gravel; strongly effervescent; moderately alkaline; clear smooth boundary.
Bw4--26 to 53 inches; light yellowish brown (10YR 6/4) sandy loam, dark yellowish brown (10YR 4/4), moist; weak medium subangular blocky structure; soft, very friable; common very fine and fine roots; 60 percent continuous distinct very pale brown (10YR 8/2), dry, carbonate coats on rock fragments; 5 percent subrounded igneous gravel; strongly effervescent; moderately alkaline; clear smooth boundary.
Bw5--53 to 76 inches; yellowish brown (10YR 5/4) fine sandy loam, dark yellowish brown (10YR 4/4), moist; weak coarse and medium subangular blocky structure; soft, very friable; few very fine and fine roots; common medium high-continuity tubular pores; 1 percent discontinuous faint very pale brown (10YR 8/2) carbonate coats on all faces of peds and 25 percent discontinuous distinct very pale brown (10YR 8/2) carbonate coats on rock fragments; 3 percent subrounded igneous gravel; strongly effervescent; moderately alkaline; clear smooth boundary. (combined thickness of Bw horizons more than 40 inches)
Btkb--76 to 83 inches; light yellowish brown (10YR 6/4) gravelly sandy loam; weak medium subangular blocky structure; loose, very friable; few very fine roots; 3 percent faint clay bridging and 20 percent discontinuous distinct very pale brown (10YR 8/2), dry, carbonate coats on rock fragments; 30 percent subrounded igneous gravel; strongly effervescent; moderately alkaline;.
TYPE LOCATION: Brewster County, Texas: from the junction of U.S. Highways 90 and 385 just east of Marathon, 49.8 miles south on U.S. Highway 385 to Terlingua Ranch Road; 4.5 miles west on Terlingua Ranch Road to intersection, 1.1 mile southwest on Terlingua Ranch Road, 200 feet south in range. (UTM Coordinates: 672,209 m E, 3,273,748 m N; NAD83 Zone 13. Bone Spring USGS 7.5 minute topographic quadrangle)
RANGE IN CHARACTERISTICS:
Soil Moisture: Ustic aridic soil moisture regime. Receives precipitation in all months. Driest period is November through April with peak rainfall occurring during May though October.
Mean annual soil temperature: 72 to 78 degrees F.
Clay content in the control section: 10 to 18 percent
Calcium carbonate content: 2 to 5 percent within a depth of 40 inches
Rock fragment content: 0 to 15 percent, mainly igneous gravel; in any one horizon of some pedons, rock fragment content may range to 35 percent but the weighted average within the particle-size control section is less than 15 percent
Reaction: neutral to moderately alkaline
A horizon
Hue: 7.5YR, 10YR
Value: 5 to 7 dry, 3 to 5 moist
Chroma: 2 to 4, dry or moist
Clay content: 7 to 18 percent
Bw horizons
Hue: 7.5YR, 10YR
Value: 5 to 7 dry, 3 to 5 moist
Chroma: 3 to 6, dry or moist
Clay content: 7 to 18 percent
Btkb horizons
Hue: 7.5YR, 10YR
Value: 5 to 7 dry, 3 to 5 moist
Chroma: 3 to 6, dry or moist
Clay content: 7 to 20 percent
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Equipaje soils are on piedmont slopes, alluvial fans, and stream terraces. Slopes are 0 to 5 percent, but dominantly 1 to 3 percent. These soils formed from Holocene-age moderately coarse textured alluvium derived from igneous and sedimentary rocks. Mean annual precipitation is 10 to 13 inches. Most precipitation occurs as high intensity rain during afternoon convective thunderstorms from June to September. Mean annual air temperature is 68 to 72 degrees F. Frost-free period is 240 to 280 days. The elevation is 2,500 to 3,500 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These soils are the
Agust and
Corazones series.
Agust soils occur on similar landforms, and have a calcic horizon and contain 15 to 35 percent by volume rock fragments in the control section.
Corazones soils occur on higher, older remnant fan and pediment geomorphic surfaces. They are skeletal and have a calcic horizon with in a depth of 40 inches.
DRAINAGE AND PERMEABILITY: Well drained; moderately rapid permeability; very slow runoff.
USE AND VEGETATION: Used mainly as ephemeral livestock grazing. Vegetation physiognomy is desert shrubland. Dominant woody plants are creosotebush, soaptree yucca, and western honey mesquite. Grasses include black grama, sand dropseed, fluffgrass, and bush muhly.
DISTRIBUTION AND EXTENT: Southern Big Bend region of Trans-Pecos Texas. LRR D, MLRA 42, Hot Desert Shrub LRU, Southern Desertic Basins, Plains, and Mountains. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Brewster County, Texas. 2008. The name, taken from a spring near the type location, is pronounced Ek-ih-pa-he.
REMARKS: Equipaje soils were formerly included in the Pajarito series.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon The zone from 0 to 2 inches (A horizon)
Cambic horizon The zone from 2 to 76 inches (Bw1, Bw2, Bw3, Bw4, and Bw5 horizons)
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Tenth Edition, 2006
Moisture and temperature regimes revised for the recorrelation of Brewster County, Texas, Main part, 2/8/08, CEM