LOCATION BORUNDA TX

Established Series
Rev. LEL/JLR/ACT
10/2012

BORUNDA SERIES

The Borunda series consists of moderately deep, well drained, moderately slowly permeable soils over slowly permeable tuffaceous bedrock. They developed in residuum and derived from tuffs of the Duff and Pruett Formations. These gently undulating to undulating soils are on fan remnants. Slopes range from 1 to 8 percent.

TAXONOMIC CLASS: Fine, mixed, superactive, thermic Ustic Calcigypsids

TYPICAL PEDON: Borunda loam - rangeland. (Colors are for dry soil unless otherwise stated.)

A--0 to 3 inches; light brown (7.5YR 6/3) loam, brown (7.5YR 5/3) moist; weak thin platy parting to weak fine subangular blocky structure; slightly hard, friable; common very fine and fine roots; common very fine and fine vesicular pores; 5 percent rounded chert gravel; 19 percent calcium carbonate equivalent; nonsaline; strongly effervescent; moderately alkaline; clear smooth boundary. (2 to 9 inches thick).

Bk--3 to 12 inches; pinkish gray (7.5YR 7/2) clay, light brown (7.5YR 6/3) moist; weak medium subangular blocky parting to weak fine subangular blocky structure; hard, firm; common very fine, fine and medium roots; common very fine, fine, and medium tubular pores; very few distinct discontinuous white (10YR 8/1) calcium carbonate coatings on surfaces of peds; few fine white (10YR 8/1) threads of calcium carbonate; 2 percent rounded chert gravel; 38 percent calcium carbonate equivalent; slightly saline; violently effervescent; moderately alkaline; clear smooth boundary. (8 to 16 inches thick).

Bky--12 to 28 inches; pinkish gray (7.5YR 7/2) clay, light brown (7.5YR 6/3) moist; weak medium and coarse subangular blocky parting to weak medium subangular blocky structure; hard, firm; few very fine and fine roots; common very fine, fine, and medium tubular pores; common coarse white (10YR 8/1) masses of calcium carbonate and common medium white (10YR 8/1) threads of calcium carbonate; few distinct discontinuous white (10YR 8/1) calcium carbonate coatings on surfaces of peds and common distinct discontinuous white (10YR 8/1) calcium carbonate coatings on rock fragments; 2 percent gypsum crystals; 2 percent rounded chert gravel; 30 percent weathered tuff rock fragments concentrated in old krotovinas; 26 percent calcium carbonate equivalent; 16 percent gypsum by weight; moderately saline; violently effervescent; moderately alkaline; clear wavy boundary. (0 to 16 inches thick).

Crk--28 to 40 inches; moderately cemented tuff bedrock; few very fine and fine roots in cracks; common coarse white (10YR 8/1) masses of calcium carbonate in cracks and common medium white (10YR 8/1) threads of calcium carbonate in cracks; few prominent discontinuous white (10YR 8/1) calcium carbonate coatings on surfaces of fractures; violently effervescent; clear smooth boundary.

Rk--40 to 51 inches; strongly cemented tuff bedrock; few very fine and fine roots in cracks; common medium white (10YR 8/1) threads of calcium carbonate in cracks; few prominent discontinuous white (10YR 8/1) calcium carbonate coatings on surfaces of fractures; strongly effervescent; clear smooth boundary.

R--51 to 62 inches; strongly cemented tuff bedrock; very few very fine and fine roots in cracks; strongly effervescent.

TYPE LOCATION: Brewster County, Texas; from the junction of U.S. Highway 90 and Texas Highway 118 in Alpine, 41.1 miles south on Texas Highway 118 to gate, 2.9 miles west on ranch road, 75 feet south in rangeland. Buck Hill USGS 7.5 minute topographic quadrangle.
Latitude: 29 degrees, 48 minutes, 36.25 seconds North; Longitude: 103 degrees, 37 minutes, 25.6 seconds West NAD83

RANGE IN CHARACTERISTICS:

Soil moisture: Ustic aridic moisture regime

Particle size control section (weighted average)
Clay content: 35 to 50 percent
Rock fragments: 0 to 15 percent tuff, limestone, and chert gravel

Depth to paralithic contact: 20 to 40 inches

Depth to lithic contact: 30 to 80 inches

A horizon
Hue: 5YR, 7.5YR, 10YR
Value: 5 to 7, dry or moist
Chroma: 2 to 4, dry or moist
Texture: loam, clay loam, silty clay loam
Calcium carbonate: films and threads range from none to 3 percent by volume in the lower part
Calcium carbonate equivalent: 5 to 20 percent by volume
Reaction: slightly alkaline or moderately alkaline

Bw horizon, where present
Hue: 5YR, 7.5YR, 10YR
Value: 5 to 7, dry or moist
Chroma: 3 to 5, dry or moist
Apparent field texture: clay, clay loam, silty clay loam
Calcium carbonate: films and threads range from none to 2 percent by volume
Calcium carbonate equivalent: 5 to 20 percent
Reaction: slightly alkaline to moderately alkaline

Bk horizon
Hue: 5YR, 7.5YR, 10YR
Value: 6 or 7, dry or moist
Chroma: 2 to 4, dry or moist
Apparent field texture: clay, clay loam, silty clay loam
Calcium carbonate: masses, films, threads, and concretions that range from 2 to 10 percent by volume
Calcium carbonate equivalent: 15 to 40 percent
Reaction: moderately alkaline or strongly alkaline

Bky horizon
Hue: 5YR, 7.5YR, 10YR
Value: 6 or 7, dry or moist
Chroma: 2 to 4, dry or moist
Apparent field texture: clay, clay loam, silty clay loam
Calcium carbonate: masses, films, threads, and concretions that range from 2 to 10 percent by volume
Calcium carbonate equivalent: 15 to 40 percent
Visible forms of gypsum: 1 to 5 percent by volume
Gypsum content: 5 to 20 percent
Reaction: moderately alkaline or strongly alkaline

C horizon, where present
Hue: 5YR to 2.5Y
Value: 5 to 7, dry or moist
Chroma: 1 to 4, dry or moist
Apparent field texture: clay, clay loam, silty clay loam

Cr and R horizons
Tuff bedrock

COMPETING SERIES: This is the Butcherknife (TX) series. Butcherknife soil depth to tuff bedrock is 40 to 60 inches.

GEOGRAPHIC SETTING: Borunda soils are on gently undulating to undulating erosional hillslopes and pediments. Slopes range from 1 to 8 percent. The soil formed in residuum and pedisediments weathered from tuff of the Duff and Pruett Formations. Mean annual precipitation ranges from 10 to 15 inches, with most occurring from July to September. Mean annual air temperature ranges from 62 to 68 degrees F. Frost-free period ranges from 210 to 260 days. Elevation ranges from 3,500 to 5,000 feet.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Butcherknife, Holguin, Martillo, Musgrave, Reduff, Scotal, and Straddlebug series. Butcherknife and Martillo soils are on Pleistocene age alluvial flats below Borunda soils. Butcherknife soils are in the fine family and are deep to weathered tuff. Martillo soils are in the fine family and are very deep. Butcherknife and Martillo soils are on broad alluvial flats in lower positions. Musgrave soils are very shallow and shallow to weathered tuffaceous bedrock. They are on gravel-mantled low scarps. Holguin, Reduff, Scotal soils are very shallow and shallow to tuff bedrock, and are in the loamy-skeletal family. They are on erosional slopes, hills, and scarps. Straddlebug soils are very deep, do not have calcic or gypsic horizons, and are on lower Holocene-age alluvial flats and floodplains.

DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderately slow or slow over slowly permeable tuffaceous bedrock. Runoff is low on slopes of less than 1 percent, medium on 1 to 5 percent slopes, and high on slopes of 5 to 8 percent.

USE AND VEGETATION: This soil is used as livestock grazing and wildlife habitat. Native vegetation consists of an overstory of creosotebush, mesquite, and whitethorn acacia, with tobosagrass dominating the herbaceous layer. Minor woody species are wolfberry, allthorn, lotebush, tarbush, and prickly pear. Other grass species include burrograss, plains bristlegrass, bush muhly, fluffgrass, red grama, alkali sacaton, and pink pappusgrass.

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

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

SERIES ESTABLISHED: Brewster County, Texas, 1997

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

Ochric epipedon - The zone from 0 to 3 inches (A horizon)

Calcic horizon - The zone from 3 to 28 inches (Bk and Bky horizons)

Gypsic horizon - The zone from 12 to 28 inches (Bky horizon) Gypsum contents determined by the water loss method of Nelson, Klameth, and Nettleton, 1978, SSSA Journal 42: 659-661

Paralithic contact - The boundary at 28 inches (Crk horizon)

Ustic feature - The soil moisture control section is dry in all parts less than three-fourths of the time (cumulative) when the soil temperature is 5 degrees centigrade or higher at a depth of 50 centimeters and the moisture regime borders an ustic regime. The soil occurs in the ustic aridic soil moisture regime.

Superactive cation activity class - CEC to clay ratio 0.60 or more. This is assumed from the abundant zeolitic minerals in the Duff and Pruett Formations, and from laboratory data from similar soils from Presidio County, Texas. The assignment of the cation-exchange activity class is supported by laboratory data number 95TX043027 from the type location in Brewster County, Texas.

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

Update and revisions for the recorrelation of Brewster County, TX, Main Part, 2/8/08, CEM.

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

ADDITIONAL DATA: NSSL Data from type location 95TX043027.

National Cooperative Soil Survey
U.S.A.