LOCATION CHORRO AZEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, thermic Sodic Ustic Haplocalcids
TYPICAL PEDON: Chorro silt loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 5 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; weak thin platy parting to weak fine subangular blocky structure; soft, very friable, slightly sticky and moderately plastic; many very fine and fine roots; few very fine and fine irregular and tubular pores; slightly effervescent, 7 percent calcium carbonate equivalent; moderately alkaline (pH 8.2); abrupt wavy boundary. (2 to 6 inches thick)
Bknyz1--5 to 14 inches; very dark gray (10YR 3/1) clay, black (10YR 2/1) moist; moderate very fine and fine prismatic parting to moderate fine angular blocky structure; slightly hard, firm, slightly sticky and very plastic; many very fine and fine roots; few very fine and fine irregular and tubular pores; many fine soft calcium carbonate and gypsum masses; strongly effervescent, 15 percent calcium carbonate equivalent; very strongly alkaline (pH 9.2); abrupt wavy boundary.
Bknyz2--14 to 27 inches; brown (7.5YR 5/3) loam, brown (7.5YR 5/2) moist; massive; soft, very friable, slightly sticky and moderately plastic; common very fine and fine roots; many fine and common medium vesicular pores; few fine gypsum crystals throughout; common fine and medium soft calcium carbonate and gypsum masses; violently effervescent, 16 percent calcium carbonate equivalent; very strongly alkaline (pH 9.4); clear wavy boundary.
Bknyz3--27 to 60 inches; pink (7.5YR 7/3) fine sandy loam, brown (7.5YR 5/3) moist; massive; slightly hard, firm, slightly sticky and moderately plastic; common very fine and few fine roots; many fine and common medium vesicular pores; common fine gypsum crystals; common fine and medium soft calcium carbonate and gypsum masses; common distinct organic coatings on ped faces and in root pores; violently effervescent, 19 percent calcium carbonate equivalent; very strongly alkaline (pH 9.6). (Combined thickness of the Bknyz horizons is 30 to 50 inches)
TYPE LOCATION: Cochise County, Arizona; located at a latitude of 31 degrees, 20 minutes, 03 seconds North and longitude of 109 degrees, 16 minutes, 00 seconds West; about 1,000 feet east and 200 feet south of the northwest corner of section 23, Township 24 S., Range 30 E.
RANGE IN CHARACTERISTICS:
Soil moisture - Intermittently moist in some part of soil moisture control section during July - September and December - February. Driest during May and June. Ustic aridic soil moisture regime.
Soil Temperature: 62 to 69 degrees F.
Reaction: slightly to very strongly alkaline
Clay content: averages 18 to 35 percent in control section
Calcium carbonate equivalent: 10 to 25 percent
Organic matter content: 1 to 2 percent
Depth to calcic horizon: 10 to 20 inches
A horizon
Hue: 10YR, 7.5YR
Value: 2 through 4, dry or moist
Chroma: 1 through 3, dry or moist
Texture: silty clay loam, silt loam, clay loam, fine sandy loam
Bknyz1 horizon
Hue: 10YR, 7.5YR
Value: 2 through 4, dry or moist
Chroma: 1 or 2, dry or moist
Texture: clay, silty clay, silty clay loam, loam
Calcium carbonate equivalent: 10 to 25 percent
Gypsum content: 2 to 5 percent
Salinity: EC of 4 to 16 dS/m
SAR: 13 to 50
Bknyz2 and Bknyz3 horizon
Hue: 10YR, 7.5YR
Value: 3 through 7 dry, 3 through 6 moist
Chroma: 2 or 3, dry or moist
Texture: fine sandy loam, loam, clay loam, silty clay loam
Calcium carbonate equivalent: 15 to 25 percent
Gypsum content: 1 to 5 percent
Salinity: EC of 4 to 32 dS/m
SAR: 13 to 60
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Chorro soils are on flood plains, basin floors, and alluvial fans that occur at elevations of 3,600 to 4,100 feet. Slopes range from 0 to 5 percent. These soils formed in mixed alluvium. The mean annual precipitation is 12 to 16 inches and occurs as thunderstorms during July to September and as gentle rains during December to February. The mean annual air temperature is 60 to 67 degrees F. The frost-free period is 180 to 230 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Riveroad, Ubik and Guest soils. These soils do not contain salts.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; slow permeability.
USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Vegetation includes alkali sacaton, tobosa, sideoats grama, and other annual grasses and forbs.
DISTRIBUTION AND EXTENT: Southeastern Arizona. Chorro soils are of moderate extent. El Chorro is a large lake in Mexico. MLRA is 41.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Cochise County, Arizona. Soil survey of Cochise County, Arizona, Douglas-Tombstone Part; San Bernardino Valley Interim Report, 1998.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 5 inches (A horizon)
Calcic horizon - The zone from 14 to 60 inches (Bknyz2, Bknyz3 horizons)
Classified according to Soil Taxonomy Second Edition, 1999