LOCATION CROT AZEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Ustic Natrargids
TYPICAL PEDON: Crot sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.)
E1--0 to 2 inches; light brownish gray (10YR 6/2) sandy loam, dark grayish brown (10YR 4/2) moist; moderate thick platy structure; slightly hard, very friable, nonsticky, nonplastic; many fine and medium and few coarse roots; common very fine and fine vesicular and interstitial pores; very slightly effervescent; strongly alkaline (pH 8.6); abrupt smooth boundary. (0 to 3 inches thick)
E2--2 to 5 inches; light brownish gray (10YR 6/2) sandy loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, very friable, nonsticky, nonplastic; common fine and medium and few coarse roots; common medium and coarse tubular pores; very slightly effervescent; moderately alkaline (pH 8.4); abrupt smooth boundary. (2 to 9 inches thick)
Btkn1--5 to 11 inches; brown (10YR 5/3) sandy clay loam, brown (10YR 4/3) moist; moderate medium and coarse columnar structure that parts to moderate medium subangular blocky structure; hard, friable, sticky, plastic; common fine and few coarse roots; common fine tubular pores; common thin clay films on faces of peds and in pores; strongly effervescent; common fine and very pale brown (10YR 8/2) soft lime masses, pale brown (10YR 6/3) moist; very strongly alkaline (pH 9.6); clear wavy boundary. (4 to 8 inches thick)
Btkng1--11 to 17 inches; mottled light gray (2.5Y 7/2) and yellowish brown (10YR 5/4) sandy clay loam, grayish brown (2.5Y 5/2) and dark yellowish brown (10YR 4/4) moist; moderate medium prismatic structure that parts to subangular blocky structure; hard, friable, slightly sticky, slightly plastic; few very fine, fine and coarse roots; many fine and very fine tubular pores; few thin clay films on faces of peds and in pores; strongly effervescent; common fine and medium very pale brown (10YR 8/2) soft lime masses, pale brown (10YR 6/3) moist; very strongly alkaline (pH 9.6); clear wavy boundary. (3 to 7 inches thick)
Btkng2--17 to 20 inches; light gray (2.5Y 7/2) coarse sandy loam, grayish brown (2.5Y 5/2) moist, few medium faint light yellowish brown (10YR 6/4) mottles, yellowish brown (10YR 5/4) moist; weak coarse prismatic structure; hard, friable, slightly sticky, nonplastic; few coarse roots; common very fine and fine tubular pores; few thin clay films in root channels; strongly effervescent; very strongly alkaline (pH 9.6); abrupt wavy boundary. (1 to 6 inches thick)
Btn--20 to 33 inches; light gray (5Y 7/2) coarse sandy loam, olive (5Y 5/3) moist; massive; hard, friable, slightly sticky, slightly plastic; few coarse roots; few fine tubular pores; few thin clay films in root channels; few fine pebbles; strongly effervescent; very strongly alkaline (pH 9.6); abrupt wavy boundary. (8 to 20 inches thick)
Cn--33 to 60 inches; light gray (5Y 7/2), pale yellow (5Y 7/3) and olive gray (5Y 5/2) stratified sand, loamy sand, sandy loam, very fine sandy loam, loam and silt loam (strata are 1/2 to 4 inches thick), olive gray (5Y 5/2), olive (5Y 5/3) and olive gray (5Y 4/2) moist; massive; slightly hard to hard, friable to loose, nonsticky to slightly sticky, nonplastic to slightly plastic; few coarse roots; common very fine interstitial and tubular pores; strongly effervescent; very strongly alkaline (pH 9.6).
TYPE LOCATION: Cochise County, Arizona; 400 feet S. and 2,550 feet E. of the NW corner of sec. 23, T.14S., R.24E.
RANGE IN CHARACTERISTICS:
Depth to the Btkn horizon: 5 to 30 inches.
The argillic horizon has 15 to 30 percent saturation with exchangeable sodium.
Mean annual soil temperature: 59 degrees to 68 degrees F.
Soil moisture: Intermittently moist in some part of the soil moisture control section during July-September and December-February and for less than 90 days cumulative in some part of the epipedon. Driest during May and June. Ustic aridic moisture regime
A horizon (present in some pedons)
Hue: 10YR or 7.5YR
Value: 5 or 6 dry and 3 or 4 moist
Chroma: 2 or 3
E horizon
Value: 6 or 7 dry and 4 or 5 moist
Chroma: 1 through 3
Texture: silt loam, sandy loam, fine sandy loam, loam and clay loam.
Reaction: moderately alkaline to very strongly alkaline.
B horizon
Hue: 5Y through 10YR (dominantly 10YR and 2.5Y)
Value: 5 through 7 dry and 4 or 5 moist
Chroma: 1 through 3
Reaction: strongly to very strongly alkaline
The gleyed horizon occurs at depths of less than 20 inches
The soil may have a buried Bt horizon at depths of 36 inches or more
The C horizon
Hue: 2.5Y or 5Y but ranges to 10YR with some 5YR mottles
Texture: sandy clay loam, clay loam, clay, loamy sand, gravelly loamy sand, gravelly sand, silt loam, loam or sandy loam.
COMPETING SERIES: These are the Gothard (AZ) and Sikes (NM) series. Gothard soils are moderately well-drained and lack gleyed mottles. Sikes soils have a watertable. Sikes would classify as an Epiaquolls or an Endoaquolls.
GEOGRAPHIC SETTING: The Crot soils are on level to nearly level alkali flats bordering playas at elevations of 3,800 to 4,300 feet. Slopes range from 0 to 2 percent but may have uneven microrelief due to wind shifting of the surface soil. These soils formed in old lake and fan deposited alluvium from mixed sources, including rhyolite, andesite, quartzite, granite and limestone. The climate is warm semiarid continental. The mean annual temperature ranges from 58 degrees to 66 degrees F. The frost-free period ranges from 155 to 220 days. The annual precipitation ranges from 10 to 12 inches and occurs as thundershowers from July through September and as gentle fall and winter rains. The months of May and June are usually dry.
GEOGRAPHICALLY ASSOCIATED SOILS: In addition to the competing Cogswell, Duncan, Gothard, Karro and Stewart soils, these are the McAllister soils. McAllister soils do not have an A2 or natric horizon and are well drained.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; very slow permeability.
USE AND VEGETATION: Used for range and limited irrigated cultivated crops. Native vegetation is alkali sacaton, saltgrass, tobosa, scattered mesquite, annual weeds and grasses, and up to 50 percent barren areas.
DISTRIBUTION AND EXTENT: Southeastern Arizona and possibly southwestern New Mexico adjacent to playas and intermittent streams. The series is moderately extensive. MLRA 41.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Cochise County (Willcox Area), Arizona, 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 5 inches (E horizons)
Natric horizon: The zone from 5 to 33 inches (Btkn and Btn horizons)
Reclassified from Aquic Natrustalfs to Ustic Natargids in 2006.
Classified according to Keys to Soil Taxonomy Ninth Edition, 2003