LOCATION OJINAGA                 TX

Established Series
Rev. LEL/RLB
10/2012

OJINAGA SERIES

The Ojinaga series consists of soils that are very shallow and shallow to a petrocalcic horizon. The soils are well drained and moderately rapidly permeable above and below a very slowly permeable petrocalcic horizon. They formed in gravelly pedisediments and occur on fan remnants. Slope ranges from 0 to 30 percent. The mean annual precipitation is about 11 inches and the mean annual air temperature is about 70 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, hyperthermic, shallow Calcic Petrocalcids

TYPICAL PEDON: Ojinaga very gravelly loam--rangeland (colors are for dry conditions unless otherwise stated).

A--0 to 6 inches; brown (10YR 5/3) very gravelly sandy loam, brown (10YR 4/3), moist; weak coarse subangular blocky structure parting to weak medium subangular blocky parting to weak fine subangular blocky, and weak medium platy structure in upper 1 inch of horizon; common very fine roots throughout; 10 percent discontinuous distinct white (10YR 8/1), dry, carbonate coats on all faces of peds and 35 percent continuous distinct white (10YR 8/1), dry, carbonate coats on rock fragments; 45 percent subangular igneous gravel; violent effervescence; strongly alkaline; gradual smooth boundary (3 to 8 inches thick).

Bk--6 to 12 inches; pale brown (10YR 6/3) very gravelly coarse sandy loam, brown (10YR 4/3), moist; weak medium subangular blocky structure; many very fine roots throughout; 50 percent continuous distinct white (10YR 8/1), dry, carbonate coats on rock fragments; 25 percent subangular igneous gravel and 30 percent subangular calcrete gravel; violent effervescence; strongly alkaline; a layer of calcrete fragments occurs at 8 inch depth with nearly continuous cementation a strongly cemented laminar cap 1 mm thick; very abrupt smooth boundary (0 to 9 inches thick).

Bkkm1--12 to 16 inches; cemented material, moist; massive; strongly cemented by carbonates, with indurated laminar cap 2-3 mm thick; common very fine roots top of horizon; 15 percent subrounded igneous gravel; violent effervescence, strongly alkaline; gradual smooth boundary.

Bkkm2--16 to 22 inches; cemented material, moist; massive; moderately cemented by carbonates; few fine roots in cracks; 12 percent continuous distinct white (10YR 8/1), dry, carbonate coats on rock fragments; 25 percent subangular igneous gravel; strong effervescence; strongly alkaline; gradual smooth boundary. (combined thickness of Bkm horizons 4 to 20 inches)

BCk1--22 to 34 inches; light gray (10YR 7/2) extremely gravelly loamy coarse sand, dark yellowish brown (10YR 4/4), moist; single grain; common very fine roots throughout; 50 percent continuous distinct white (10YR 8/1), dry, carbonate coats on rock fragments; 35 percent extremely coarse irregular white (10YR 8/1), dry, carbonate masses throughout; 65 percent subangular igneous gravel; violent effervescence; strongly alkaline; gradual smooth boundary.

BCk2--34 to 49 inches; light gray (10YR 7/2) extremely gravelly loamy coarse sand, dark yellowish brown (10YR 4/4), moist; single grain; common fine roots throughout and common very fine roots throughout; 35 percent continuous distinct white (10YR 8/1), dry, carbonate coats on rock fragments; 2 percent fine platy white (10YR 8/1), dry, carbonate masses throughout; 62 percent subangular igneous gravel and 3 percent subangular igneous cobbles; violent effervescence; strongly alkaline; clear smooth boundary.

CBk1--49 to 57 inches; light gray (10YR 7/2) extremely gravelly coarse sandy loam, dark yellowish brown (10YR 4/4), moist; single grain; common very fine roots throughout; 10 percent discontinuous distinct white (10YR 8/1), dry, carbonate coats on rock fragments; 1 percent fine irregular extremely weakly cemented white (10YR 8/1), dry, carbonate masses on bottom of rock fragments; 80 percent subangular igneous gravel and 5 percent subangular igneous cobbles; strong effervescence; strongly alkaline; clear smooth boundary.

CBk2--57to 69 inches; light gray (10YR 7/2) extremely gravelly coarse sandy loam, yellowish brown (10YR 5/4), moist; single grain; 25 percent discontinuous distinct white (10YR 8/1), dry, carbonate coats on rock fragments; 2 percent coarse irregular moderately cemented white (10YR 8/1), dry, carbonate nodules on bottom of rock fragments; 25 percent subangular igneous gravel; strong effervescence,; strongly alkaline; clear smooth boundary.

C--69 to 80 inches; brown (10YR 5/3) extremely gravelly loamy coarse sand, brown (10YR 4/3), moist; single grain; 35 percent discontinuous prominent white (10YR 8/1), dry, carbonate coats on rock fragments; 1 percent very coarse cylindrical very pale brown (10YR 8/2), dry, carbonate masses throughout; 65 percent subangular igneous gravel; violent effervescence; strongly alkaline

TYPE LOCATION: Presidio County, Texas; From the junction of US Highway 67 and RM 170 north of Presidio, 8.6 miles north on US Highway 67; 1.8 miles west on ranch road, then 250 feet north in range. Arroyo Melado USGS 7.5 minute quadrangle. Latitude: 29 degrees 42 minutes 35.7 seconds N, Longitude: 104 degrees 23 minutes 9.9 seconds W NAD83; UTM coordinates: 559382 meters Easting, 3286799 meters Northing, UTM Zone 13.

RANGE IN CHARACTERISTICS:

Soil Moisture: The moisture control section is dry in all parts more than three-fourths of the time the soil temperature exceeds 41 degrees F. Intermittently moist in some part of the soil moisture control section during June-September. Ustic aridic soil moisture regime.

Soil temperature: 70 to 78 degrees F.

Depth to petrocalcic horizon: 6 to 20 inches
Petrocalcic horizon thickness: 4 to 15 inches thick
Depth to calcic: 2 to 6 inches

Particle-size control section (weighted average)
Clay content: 5 to 28 percent
Rock fragment content: more than 35 percent
Calcium carbonate equivalent: 5 to 40 percent

Ak or A horizons
Hue: 7.5YR, 10YR
Value: 5 to 7 dry, 4 or 5 moist
Chroma: 2 to 4, dry or moist
Texture: sandy loam, loam, fine sandy loam, sandy clay loam
Clay content: 5 to 28 percent
Rock fragment content: 15 to 75 percent, mostly igneous gravel and cobbles

Bk horizon (where present)
Hue: 7.5YR, 10YR
Value: 5 to 8 dry, 4 to 7 moist
Chroma: 2 to 4, dry or moist
Texture: sandy loam, loam, fine sandy loam, sandy clay loam
Clay content: 5 to 28 percent
Rock fragment content: 35 to 85 percent, mostly igneous gravel and cobbles

Bkkm horizon
Strongly cemented material, becoming less cemented with depth.
Indurated laminar cap 2 to 20 mm thick in some pedons.
Thickness: 4 to 20 inches

BCk horizon
Hue: 7.5YR, 10YR
Value: 5 to 8 dry, 4 to 7 moist
Chroma: 2 or 3, dry or moist
Texture: coarse sand, loamy coarse sand, sandy loam, fine sandy loam, loam
Rock fragment content: 35 to 85 percent igneous gravel and cobbles
Clay content: 5 to 18 percent

COMPETING SERIES: These are the Cheosa (TX), Guvo (AZ), and Hickiwan (AZ) series. Guvo and Cheosa soils have a lithic contact within 40 inches of the surface. Hickiwan soils have very thick petrocalcic horizons. Guvo and Hickiwan are in the Typic Aridic soil moisture regime. Cheosa soils have conglomerate bedrock at 20 to 40 inches.

GEOGRAPHIC SETTING: Ojinaga soils are on fan remnants. They formed in gravelly pediment alluvium. Slopes range from 0 to 30 percent. Elevation ranges from 1,800 to 4,000 feet. The mean annual air temperature is 68 to 72 degrees F. The frost-free period is 240 to 280 days. The mean annual precipitation is 10 to 13 inches. Precipitation falls during afternoon thunderstorms mostly from July to September. The driest months are March and April.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chillon (P TX) and Corazones series. Chillon and Corazones soils occur on lower, younger geomorphic surfaces and do not contain a petrocalcic horizon. Chillon soils contain cambic horizons, whereas Corazones soils contain calcic horizons.

DRAINAGE AND PERMEABILITY: Well drained to excessively drained. Runoff is high on slopes less than 1 percent and very high on slopes greater than 1 percent. Permeability is moderately rapid above and below the very slowly permeable petrocalcic horizon.

USE AND VEGETATION: Used as ephemeral rangeland. Vegetation physiognomy is desert shrubland. Dominant woody plants are creosotebush, mesquite, leatherstem, lechuguilla, and ocotillo. Grasses include chino grama and fluffgrass.

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.

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

Particle-size control section: 0 to 12 inches; Ak and Bk horizons

Ochric epipedon: The zone from 0 to 12 inches (Ak horizon)

Calcic horizon: The zone from 0 to 12 inches (Ak and Bk horizons)

Petrocalcic horizon: The zone from 12 to 20 inches (Bkm and BKm2 horizons)

Calcic feature: The calcic horizon above the petrocalcic horizon

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

Updated competing series section 4/9/08, CEM

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

ADDITIONAL DATA: Data from TAMU Soil Characterization Lab are available for the typical pedon, S04TX377-001.

---

National Cooperative Soil Survey
U.S.A.