LOCATION HORSETRAP TX

Established Series
DWM/LEL
10/2012

HORSETRAP SERIES

The Horsetrap series consists of shallow, well drained soils that formed in loamy colluvium and residuum from basalt. Horsetrap soils are on dissected plateaus, hills and mountains. Slope ranges from 0 to 45 percent. The annual precipitation is about 13 inches and mean annual air temperature is about 64 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Lithic Ustic Haplocambids

TYPICAL PEDON: Horsetrap gravelly sandy clay loam rangeland. (Colors are for dry soil unless otherwise noted.)

A--0 to 4 inches; grayish brown (10YR 5/2) gravelly sandy clay loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure parting to weak fine granular structure; very friable, slightly hard; common very fine roots; 25 percent basalt gravel basalt; noneffervescent; slightly alkaline; abrupt smooth boundary. (2 to 10 inches thick)

Bk1--4 to 8 inches; grayish brown (10YR 5/2) very gravelly clay loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; very friable, slightly hard; common fine roots; 5 percent fine irregular carbonate masses; 35 percent fine basalt gravel; thin coatings and pendants of carbonate on rock fragments; strong effervescence; moderately alkaline; clear smooth boundary.

Bk2--8 to 13 inches; grayish brown (10YR 5/2) very gravelly clay loam, dark grayish brown (10YR 4/2) moist; moderate medium subangular blocky structure; very friable, slightly hard; common fine roots throughout; 5 percent fine irregular carbonate masses throughout; 35 percent fine basalt gravel; thin coatings and pendants of carbonate on rock fragments; strong effervescence; moderately alkaline; abrupt smooth boundary (Combined thickness of the Bk horizon is 8 to 20 inches thick)

R--13 inches; basalt bedrock; carbonate coats on surface of bedrock; strong effervescence.

TYPE LOCATION: Presidio County, Texas; from junction of U.S. Highway 67 and FM 170 in Presidio, 7.8 miles east on FM 170, 6.0 miles north on Casa Piedra Road to junction, 19.8 miles east on road to Sauceda Ranch Headquarters, Big Bend Ranch State Park, east from Sauceda Ranch Headquarters 2.8 miles, 1.0 mile southeast on road to gate, 0.10 mile southwest on road; and 50 feet southeast from road. Sauceda Ranch USGS topographic quadrangle; Located at a latitude of 29 degrees, 27 minutes, 27.36 seconds North and a longitude of 103 degrees, 54 minutes, 25.31 seconds West NAD83. UTM coordinates 605986 m E, 3259183 m N, Zone 13.

RANGE IN CHARACTERISTICS:
Soil Moisture: Ustic aridic soil moisture regime. The soil moisture control section is usually dry in all parts less than three-fourths of the time that the soil temperature exceeds 41 degrees F

Soil Temperature: 64 to 68 degrees F
Rock fragment surface cover: 40 to 90 percent
Depth to bedrock: 10 to 20 inches

Particle-size control section (weighted average)
Clay content: 15 to 35 percent
Rock fragments: greater than 35 percent

A horizon
Hue: 7.5YR, 10YR, 2.5Y
Value: 3 to 6 dry, 2 to 4 moist
Chroma: 2 to 4, dry or moist
Texture: sandy loam, loam, sandy clay loam, clay loam
Clay content: 12 to 30 percent
Rock fragments: 10 to 50 percent
Calcium carbonate equivalent: 0 to 15 percent
Reaction: neutral or moderately alkaline

Bk horizon
Hue: 7.5YR, 10YR, 2.5Y
Value: 3 to 7 dry, 3 to 6 moist
Chroma: 2 to 4, dry or moist
Texture: loam, clay loam, sandy clay loam, sandy loam
Clay content: 18 to 35 percent
Rock fragments: 35 to 60percent; gravels and/or cobbles
Calcium carbonate equivalent: 5 to 15 percent
Reaction: slightly or moderately alkaline

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Horsetrap soils are on dissected plateaus, hills and mountains at elevations of 3,500 to 5,500 feet. Slopes range from 0 to 45 percent. These soils formed in loamy residuum and colluvium from basalt. The mean annual precipitation is 12 to 16 inches and precipitation falls mostly during the months of July to September. The driest months are March and April. The mean annual air temperature is 62 to 67 degrees F. The frost-free period is 210 to 250 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bofecillos, Leyva and Pantak soils. Bofecillos soils are very shallow to basalt bedrock and lack a cambic horizon. Leyva soils have an argillic horizon and are shallow to siliceous extrusive bedrock. Pantak soils have an argillic horizon.

DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately slow in the surface over very slowly permeable bedrock. Runoff is low on slope sless than 1 percent, medium on 1 to 5 percent slopes, high on 5 to 20 percent sliopes, and very high on slopes greater than 20 percent.

USE AND VEGETATION: This soil is used mainly for livestock grazing and wildlife habitat. Native vegetation is desert grassland with abundant woody plants. Shrubs include mariola, creosote bush, Engelmann pricklypear, whitethorn acacia, ocotillo, tasajillo, western honey mesquite, strawberry pitaya, cholla, elbowbush, catclaw acacia, lechuguilla, brownspine pricklypear, Texas rainbow cactus, Torrey yucca, tarbush, and Wright's beebrush. Grasses include fluffgrass, chino grama, bush muhly, purple threeawn, black grama, sixweeks grama, plains bristlegrass, and Hall's panicum. Forbs include leatherweed and California caltrop.

DISTRIBUTION AND EXTENT: West Texas. MLRA 42. The series is moderately extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona

SERIES ESTABLISHED: Hudspeth County, Texas; Soil Survey of Hudspeth County, Texas (Main Part), 2012. The name is taken from the Horsetrap Pasture, Big Bend Ranch State Park.

REMARKS:
Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - the zone from 0 to 4 inches (A horizon)

Cambic horizon - the zone from 4 to 13 inches (Bk1, Bk2 horizons)

Lithic contact - the upper boundary the bedrock at 13 inches (R layer)

Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Eleventh Edition, 2010

Revised for the correlation of Hudspeth County, Texas (Main Part) and Culberson County, Texas (Main Part); July, 2012, NMS

Revised for the correlation of Presidio County, Texas ; Oct, 2012, WWJ

National Cooperative Soil Survey
U.S.A.