LOCATION CHOZA                   TX

Established Series
ALS, WJG
08/2012

CHOZA SERIES

The Choza series consists of very shallow and shallow, well drained soils that formed in gravelly fan alluvium. Choza soils are on moderately sloping to moderately steep dissected alluvial fan remnants. Slopes are 5 to 35 percent. Mean annual temperature is about 16 degrees C (61 degrees F) and mean annual precipitation is about 411 mm (16 in).

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic, shallow Petrocalcic Calciustolls

TYPICAL PEDON: Choza very gravelly loam, on an east-facing 6 percent slope in rangeland at an elevation of 1,678 m (5,505 ft). (Colors are for dry soil unless otherwise noted).

A1--0 to 15 cm, (0 to 6 in); dark grayish brown (10YR 4/2) very gravelly loam, very dark grayish brown (10YR 3/2), moist; moderate fine and medium granular structure; soft, friable, slightly sticky, moderately plastic; 5 percent subrounded 76 to 250 mm limestone fragments and 30 percent subrounded 5 to 75 mm limestone fragments; strongly effervescent; moderately alkaline; clear smooth boundary.

A2--15 to 26 cm, (6 to 10 in); brown (10YR 4/3) very gravelly loam, dark brown (10YR 3/3), moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky, moderately plastic; 5 percent subrounded 76 to 250 mm limestone fragments and 30 percent subrounded 5 to 75 mm limestone fragments; strongly effervescent; moderately alkaline; very abrupt smooth boundary. (Combined thickness of the A horizon is 13 to 38 cm [5 to 15 in])

Bkm--26 to 51 cm, (10 to 20 in); very pale brown (10YR 8/2) cemented material, very pale brown (10YR 8/2), moist; 2 mm thick prominent irregular indurated cemented carbonate laminae on top of horizon.

TYPE LOCATION: Culberson County, Texas; from the intersection of U.S. Highway 62/180 and the Guadalupe Mountains National Park entrance to Friojle Ranch, 0.75 mile west on park road to Frijole Ranch Museum; 0.12 mile north-northeast on Smith Springs trail; site is 0.1 mile southeast of trail along an arroyo. (Guadalupe Peak TX USGS topographic quadrangle: Latitude: 31 degrees, 54 minutes, 31 seconds N; Longitude: 104 degrees, 47 minutes, 57 seconds W; UTM Easting 518989 m, UTM Northing 3530309 m, UTM Zone 13, NAD83.)

RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon: 13 to 38 cm (5 to 15 in)
Depth to petrocalcic horizon: 13 to 38 cm (5 to 15 in)

Particle-size control section (weighted average):
Clay Content: 12 to 32 percent
Rock fragment content: 35 to 70 percent total; 10 to 40 percent gravel; 5 to 40 percent cobbles

A horizon
Hue: 7.5YR or 10YR
Value: 3 or 4 dry, 2 or 3 moist
Chroma: 2 or 3 dry, 1 to 3 moist
Texture of the fine-earth fraction: fine sandy loam, loam, or sandy clay loam
Clay content: 12 to 32 percent
Coarse fragments: 35 to 65 percent total; 10 to 30 percent gravel; 5 to 40 percent cobbles
Effervescence: strongly or violently
Reaction: slightly alkaline or moderately alkaline

Bk horizon (where present)
Hue: 7.5YR or 10YR
Value: 4 to 8 dry, 3 to 7 moist
Chroma: 2 to 4 dry or moist
Texture of the fine-earth fraction: loam or, sandy clay loam
Clay content: 20 to 25 percent
Coarse fragments: 35 to 45 percent total; 30 to 40 percent gravel; 10 to 15 percent cobbles
Effervescence: strongly or violently
Reaction: slightly alkaline to strongly alkaline

Bkm horizon
Hue: 7.5YR or 10YR
Value: 3 to 6 dry, 2 to 5 moist
Chroma: 2 to 6 dry or moist
Effervescence: strong or violent
Reaction: moderately alkaline

COMPETING SERIES: There are Boracho (TX), Dermott (TX) and Laverne (TX) soils.
Boracho soils: are derived from igneous parent materials.
Dermott and Laverne soils: are derived from Ogallala parent materials.

GEOGRAPHIC SETTING:
Parent Material: fan alluvium from limestone sources
Landscape: piedmont
Landform: dissected alluvial fan remnants
Slope: 5 to 20 percent
Soil Moisture: Aridic Ustic moisture regime
Mean annual soil temperature: 15 to 20 degrees C (59 to 68 degrees F)
Mean annual air temperature: 14 to 19 degrees C (57 to 66 degrees F)
Mean annual precipitation: 287 to 523 mm (11 to 20 in)
Precipitation pattern: Most precipitation occurs as high intensity rain during afternoon convective thunderstorms from June to September.
Frost-free period: 203 to 255 days
Elevation: 1,370 to 1,995 m (4,495 to 6,545 ft)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Altuda (TX) and the tentative Bonespring (TX) and Pinery (TX) soils.
Altuda soils: have a lithic contact and occur on limestone hills and ridges.
Bonespring soils: have a lithic contact and occur on sandstone hills and ridges.
Pinery soils: do not have a petrocalcic horizon and occur on similar positions.

DRAINAGE AND PERMEABILITY: Well drained; Runoff is medium on 5 to 10 percent slopes and high on slopes over 10 percent; moderately rapid permeability.

USE AND VEGETATION: This soil is used for livestock grazing, wildlife habitat and recreation. Vegetation is curlyleaf muhly, hairy grama, black grama, skunkbush sumac, sotol, pricklypear, redberry juniper, oaks, and pinyon pine.

DISTRIBUTION AND EXTENT: LRR G; Western Great Plains Range and Irrigated Region; MLRA 70D-Southern Desert Foothills in West Texas. The soil is not extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Culberson County, Texas; 2010. The name is taken from a spring occurring in Guadalupe Mountains National Park.

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

Mollic epipedon: 0 to 26 cm (0 to 10 in) (A1 and A2 horizons)
Petrocalcic horizon: 26 to 51 cm (10 to 20 in) (Bkm layer)

The taxonomic version is Keys to Soil Taxonomy, Eleventh Edition, 2010

ADDITIONAL DATA: None

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National Cooperative Soil Survey
U.S.A.