LOCATION CRISTOBAL AZEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, hyperthermic Typic Calciargids
TYPICAL PEDON: Cristobal very gravelly loam - rangeland. (Colors are for dry soil unless otherwise noted) 90 to 95 percent of the surface is covered with gravel with a thin desert varnish.
Ez--0 to 2 inches; pale brown (10YR 6/3) extremely gravelly loam, dark brown (10YR 3/3) moist; moderate thin and medium platy structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine vesicular pores; 60 percent fine and medium gravel; strongly effervescent; strongly saline; moderately alkaline (8.2); abrupt smooth boundary. (1/2 to 3 inches thick)
Btkz1--2 to 6 inches; red (2.5YR 5/6) very gravelly clay loam, dark red (2.5YR 3/6) moist; moderate and strong very fine granular structure; soft, very friable, moderately sticky and moderately plastic; many fine irregular pores; few faint clay films on faces of peds; 35 percent fine gravel with underside coated with calcium carbonate; few fine and medium soft calcium carbonate accumulations; strongly effervescent; strongly saline; moderately alkaline (pH 8.2); clear wavy boundary. (2 to 10 inches thick)
Btkz2--6 to 10 inches; yellowish red (5YR 5/6) very gravelly clay loam, dark reddish brown (5YR 3/4) moist; moderate and strong fine granular structure; soft, very friable, moderately sticky and moderately plastic; many very fine irregular pores; few to common faint clay films on faces of peds; 50 percent fine and medium gravel with underside coated with calcium carbonate; common fine and medium soft calcium carbonate accumulations; common very fine and fine salt crystals; strongly effervescent; strongly saline; moderately alkaline (pH 8.2); clear wavy boundary. (4 to 5 inches thick)
Btkz3--10 to 17 inches; yellowish red (5YR 4/6) extremely gravelly clay loam, dark reddish brown (5YR 3/4) moist; weak fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; many very fine tubular pores; few faint clay films on faces of peds and lining pores; 70 percent fine and medium gravel with underside coated with calcium carbonate; many fine and medium soft calcium carbonate accumulations; common very fine and fine salt crystals; strongly effervescent; strongly saline; moderately alkaline (pH 8.2); clear wavy boundary. (6 to 12 inches thick)
Btkz4--17 to 25 inches; yellowish red (5YR 5/6) very gravelly sandy clay loam, dark reddish brown (5YR 3/4) moist; weak fine subangular blocky structure; slightly hard, very friable, moderately sticky and slightly plastic; many very fine tubular pores; few faint clay films on faces of peds and lining pores; 60 percent fine, partially calcium carbonate coated gravel; common fine and medium soft calcium carbonate accumulations; common very fine salt crystals; strongly effervescent; strongly saline; moderately alkaline (pH 8.2); clear wavy boundary. (7 to 12 inches thick)
Btkz5--25 to 35 inches; reddish yellow (7.5YR 6/6) very gravelly clay loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; slightly hard, very friable, moderately sticky and slightly plastic; many very fine tubular pores; few faint clay films lining pores; 60 percent fine, partially calcium carbonate coated gravel; many fine and medium soft calcium carbonate accumulations; common very fine salt crystals; strongly effervescent; strongly saline; moderately alkaline (pH 8.2); clear wavy boundary. (6 to 11 inches thick)
Btkz6--35 to 60 inches; light brown (7.5YR 6/4) very gravelly clay loam, brown (7.5YR 5/4) moist; weak fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine tubular pores; few faint clay films lining pores; 60 percent fine gravel; strongly effervescent; strongly saline; moderately alkaline (pH 8.2).
TYPE LOCATION: Yuma County, Arizona; 1,100 feet west and 1,000 feet south of the northeast corner of section 28, T. 5 S., R. 13 W.
RANGE IN CHARACTERISTICS:
Soil Moisture: Usually dry, intermittently moist in some part of the soil moisture control section during July-September and December-February. Driest during May and June. Typic aridic soil moisture regime.
Rock Fragments: 35 to 70 percent
Salinity: Nonsaline to strongly saline
Sodicity: Nonsodic to strongly sodic
Reaction: slightly to moderately alkaline
Clay Content: Averages more than 18 percent in the control section
Depth to calcic horizon: 2 to 40 inches. Calcium carbonate equivalent ranges to 25 percent
Depth to base of argillic horizon: More than 40 inches
A or E horizon
Hue: 7.5YR, 10YR
Value: 4 to 6 dry, 3 to 6 moist
Chroma: 3 to 6, dry or moist
Calcium carbonate: Slightly effervescent to strongly effervescent
B horizon
Hue: 2.5YR, 5YR, 7.5YR
Value: 4 to 6 dry, 3 to 5 moist
Chroma: 4 to 6, dry or moist
Texture: Loam, sandy clay loam, clay loam
COMPETING SERIES: These are the Chuckawalla (CA), Cololag (NV) and Pinamt (AZ) series. Chuckawalla soils are less than 25 inches to the base of the argillic horizon. Cololag soils are less than 29 inches to the base of the argillic horizon and occur in Mojave Desert of southern Nevada; MLRA 30. Pinamt soils are 25 to 40 inches to the base of the argillic horizon.
GEOGRAPHIC SETTING: Cristobal soils are on fans terraces and have slopes of 0 to 20 percent. These soils formed in fan alluvium from mixed sources. Elevations range from 250 to 1,800 feet. The mean annual precipitation ranges from 2 to 10 inches. The mean annual air temperature is 69 to 76 degrees F. The frost-free period is 240 to 365 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Antho, Ebon, Gunsight, Mohall, Momoli, Rillito and Tremant soils. Antho soils are coarse-loamy and Ebon soils are clayey-skeletal. Mohall and Tremant soils are fine-loamy. Gunsight, Momoli and Rillito soils do not have an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; rapid or medium runoff; moderately slow permeability.
USE AND VEGETATION: Cristobal soils are used for livestock grazing and wildlife habitat. The present vegetation is creosotebush, bursage, cactus, paloverde, ironwood, and annual grasses and forbs.
DISTRIBUTION AND EXTENT: South-central and southwestern Arizona. This series is extensive. MLRA is 40.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Yuma County (Yuma-Wellton Area), Arizona; 1978.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 2 inches (E horizon)
Argillic horizon - The zone from 2 to 60 inches (Btkz1 thru Btkz6)
Calcic horizon - The zone from 2 to 60 inches (Btkz1 thru Btkz6)