LOCATION ZAPOLOTE AZEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Ustertic Calciargids
TYPICAL PEDON: Zapolote clay loam - rangeland. (Colors are for dry soil unless otherwise noted.) Typically 40 to 50 percent of the surface is covered with gravel.
A1--0 to 1 inch; reddish brown (5YR 5/4) clay loam, reddish brown (5YR 5/4) moist; weak thin platy structure; soft, very friable, very sticky and very plastic; many very fine roots; few fine vesicular pores; strongly effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary.
A2--1 to 5 inches; reddish brown (5YR 5/4) clay loam, reddish brown (5YR 5/3) moist; weak medium subangular blocky structure; soft, very friable, very sticky and very plastic; many very fine and fine roots; common fine irregular and tubular pores; 2 to 5 percent petronodes; 24 percent calcium carbonate equivalent, violently effervescent; moderately alkaline (pH 8.0); abrupt wavy boundary. (Combined thickness of the A horizons is 1 to 8 inches)
Btky--5 to 29 inches; reddish brown (5YR 4/3) clay, reddish brown (5YR 4/4) moist; strong medium prismatic and strong medium angular blocky structure; slightly hard, very friable, very sticky and very plastic; common fine roots; few fine tubular pores; common distinct clay films on ped faces; many distinct pressure faces; many coarse soft calcium carbonate and gypsum masses; few faint manganese coats on ped faces; 5 to 10 percent petronodes; 30 percent calcium carbonate equivalent, violently effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (20 to 30 inches thick)
Bky--29 to 60 inches; reddish brown (5YR 5/4) clay, light reddish brown (5YR 6/4) moist; massive; slightly hard, very friable, very sticky and very plastic; few very fine roots; few fine tubular pores; many coarse soft calcium carbonate and gypsum masses; many distinct manganese coats on ped faces; 5 to 10 percent petronodes; 20 percent calcium carbonate equivalent, violently effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Cochise County, Arizona; located at a latitude of 31 degrees, 23 minutes, 10 seconds North and longitude of 109 degrees, 09 minutes, 40 seconds West; section 35, Township 23S, Range 31E.
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.
Soil cracking: cracks from 7 to 29 inches deep with each crack from 1/4 to 1/2 inches wide and 2 to 5 inches long.
Reaction: slightly or moderately alkaline
Clay content: 40 to 55 percent in the control section
Depth to calcic horizon: 5 to 20 inches
A horizon
Hue: 5YR, 7.5YR
Value: 4 through 6, dry or moist
Chroma: 3 or 4 dry, 2 or 3 moist
Texture: clay loam, loam, sandy clay loam
Btky and Bky horizons
Hue: 5YR, 7.5YR
Value: 3 through 5 dry, 4 through 6 moist
Chroma: 3 through 5, dry or moist
Texture: clay, clay loam
Calcium carbonate equivalent: 20 to 35 percent
Gypsum content: 1 to 5 percent
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Zapolote soils are on relict basin floors, alluvial fans, and low fan terraces at elevations of 3,700 to 4,200 feet. Slopes range from 1 to 15 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 Luckyhills and Kahn soils. Luckyhills soils are coarse-loamy and Kahn soils are fine-loamy.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; very slow permeability.
USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Vegetation includes tobosa, tarbush, creosote, sacaton, catclaw, and desert zinnia.
DISTRIBUTION AND EXTENT: Southern Arizona. Zapolote soils are of moderate extent. 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 Interim Report, 1998.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 5 inches (A1, A2 horizons)
Calcic horizon - The zone from 5 to 60 inches (Btky, Bky horizons)
Classified according to Soil Taxonomy Second Edition, 1999; Keys to Soil Taxonomy Tenth Edition, 2006.