LOCATION COOLIDGE AZEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, hyperthermic Typic Haplocalcids
TYPICAL PEDON: Coolidge sandy loam - cultivated. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 13 inches; light yellowish brown (10YR 6/4) sandy loam, brown (10YR 4/3) moist; massive; slightly hard, very friable, nonsticky and nonplastic; common very fine tubular pores; violently effervescent; moderately alkaline (pH 8.2); abrupt smooth boundary. (6 to 14 inches thick)
Bk1--13 to 24 inches; light yellowish brown (10YR 6/4) sandy loam, dark yellowish brown (10YR 4/4) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few fine tubular pores; many fine irregular calcium carbonate filaments; violently effervescent; moderately alkaline (pH 8.2); abrupt smooth boundary. (8 to 16 inches thick)
Bk2--24 to 42 inches; pale brown (10YR 6/3) sandy loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; many fine tubular pores; many soft calcium carbonate filaments and masses; violently effervescent; moderately alkaline (pH 8.4); abrupt wavy boundary. (10 to 30 inches thick)
Bk3--42 to 60 inches; pale brown (10YR 6/3) sandy loam, brown (10YR 5/3) moist; massive; very hard, very friable, slightly sticky and slightly plastic; few medium tubular pores; 5 percent gravel; many fine soft calcium carbonate filaments and masses; violently effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Maricopa County, Arizona; 900 feet west and 2,600 feet north of the northeast corner of section 8, T. 1 N., R. 2 W., latitude 33 degrees, 26 minutes, 33 seconds N., longitude 112 degrees, 28 minutes, 54 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Soil moisture - 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.
Soil Temperature - 72 to 80 degrees F.
Rock fragments - Averages less than 15 percent in the particle size control section; but can have up to 35 percent in any one horizon
Depth to calcic horizon - 14 to 40 inches
Calcium carbonate equivalent - ranges from 6 to about 25 percent; as segregated soft masses or concretions. Some horizons have calcium carbonate filaments and coatings on ped or rock faces. All horizons contain disseminated calcium carbonate.
A horizon
Hue: 10YR, 7.5YR
Value: 5, 6 or 7 dry, 3, 4 or 5 moist
Chroma: 2, 3, 4 or 6, dry or moist
Organic matter: less than 1 percent
B horizon
Hue: 10YR, 7.5YR, 5YR
Value: 5, 6, 7 or 8 dry, 3, 4, 5 or 6 moist
Chroma: 2, 3, 4 or 6, dry or moist
Texture: Sandy loam, fine sandy loam; some pedons have thin (1/4 to 1 inch thick) strata of finer or coarser soil material in the control section
COMPETING SERIES: These are the Aco (CA), Garywash (T)(CA), Laveen (AZ), Rillito (AZ), and Toltec (AZ) series. Aco and Garywash soils are moist in some part of the soil moisture control section for less than 20 days cumulative between July and September. Aco soils have fine sand below the particle-size control section. Garywash soils have secondary accumulations of silica and gypsum in the control section. Laveen soils are loam and very fine sandy loam in the particle-size control section. Rillito soils have 15 to 35 percent gravel. Toltec soils have a calcic horizon that consists of a disintegrated hardpan.
GEOGRAPHIC SETTING: Coolidge soils are on fan terraces, stream terraces or relict basin floors and have slopes of 0 to 5 percent. Elevation ranges from 300 to 1,900 feet. These soils formed in stratified stream or fan alluvium from mixed sources. The climate is hot arid continental. The mean annual precipitation is 3 to 10 inches. Mean annual air temperature ranges from 68 to 74 degrees F. The frost-free period is 240 to 325 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Antho, Denure, Mohall and competing Rillito soils. Antho soils do not have calcic horizons. Denure soils have cambic horizons. Mohall soils are fine-loamy and have argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; very low to medium runoff; moderately rapid permeability.
USE AND VEGETATION: These soils are used for livestock grazing, wildlife habitat and irrigated cropland. Present vegetation is cacti, creosotebush, mesquite, triangleleaf bursage, annual weeds and grasses.
DISTRIBUTION AND EXTENT: Southern Arizona. The series is extensive. Total extent is about 102,000 acres. MLRA is 40.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Pinal County, Arizona; Casa Grande Area soil survey; 1936.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 13 inches (Ap horizon)
Calcic horizon - the zone from 13 to 60 inches (Bk1, Bk2, Bk3 horizons)
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Tenth Edition, 2006.
Revised for the correlation of AZ661, 12/2008, WWJ.