LOCATION BLACKTAIL               AZ

Established Series
Rev. WAS
10/2014

BLACKTAIL SERIES

The Blacktail series consists of very deep, well drained soils that formed in fan alluvium from mixed sources. Blacktail soils are on fan remnants, sideslopes, and pediments. Slopes range from 1 to 60 percent. The mean annual precipitation is about 18 inches (457 mm) and the mean annual air temperature is about 60 degrees F (15.6 degrees C).

TAXONOMIC CLASS: Fine, mixed, superactive, thermic Calcidic Argiustolls

TYPICAL PEDON: Blacktail gravelly loam rangeland. (colors are for dry soil unless otherwise noted)
A--0 to 3 inches (0 to 8 cm); dark brown (7.5YR 3/2) gravelly loam, dark reddish brown (5YR 3/2) moist; weak fine granular structure; soft, very friable, moderately sticky and moderately plastic; common very fine and fine roots; common fine irregular pores; 20 percent gravel; very slightly effervescent; slightly alkaline (pH 7.6); abrupt smooth boundary. (2 to 8 inches or 5 to 20 cm thick)

Bt--3 to 7 inches (8 to 18 cm); dark reddish brown (5YR 3/2) clay loam, dusky red (2.5YR 3/2) moist; moderate fine subangular blocky structure; soft, friable, moderately sticky and moderately plastic; common very fine and fine roots; common fine irregular pores; common distinct clay films on ped faces and in pores; 5 percent gravel; very slightly effervescent; slightly alkaline (pH 7.6); abrupt smooth boundary. (3 to 12 inches or 8 to 30 cm thick)

Btk1--7 to 17 inches (18 to 43 cm); dark reddish brown (5YR 3/4) clay, dark reddish brown (5YR 3/3) moist; moderate medium prismatic structure parting to strong medium angular blocky; extremely hard, very firm, very sticky and very plastic; common very fine and fine roots; common fine irregular pores; many distinct clay films on ped faces, in pores, and few patchy organic coatings on ped faces; few fine irregular soft masses and few fine filaments of calcium carbonate; 5 percent gravel; strongly effervescent; slightly alkaline (pH 7.8); abrupt smooth boundary. (8 to 12 inches or 20 to 30 cm thick)

Btk2--17 to 23 inches (43 to 58 cm); brown (7.5YR 5/4) clay loam, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure; soft, very friable, moderately sticky and moderately plastic; common fine and medium roots; common very fine and fine irregular pores; very few distinct clay films on ped faces; common coarse irregular soft masses of calcium carbonate; 10 percent gravel; violently effervescent, 28 percent calcium carbonate equivalent; moderately alkaline (pH 8.2); clear wavy boundary. (5 to 10 inches or 13 to 25 cm thick)

Btk3--23 to 32 inches (58 to 81 cm); pinkish white (7.5YR 8/2) sandy loam, pink (7.5YR 7/4) moist; massive; soft, very friable, slightly sticky and slightly plastic; few very fine and fine roots; many distinct clay films on rock fragments; many distinct calcium carbonate coatings on rock fragments; 10 percent gravel; violently effervescent, 60 percent calcium carbonate equivalent; moderately alkaline (pH 8.4); clear wavy boundary. (8 to 12 inches or 20 to 30 cm thick)

2Bk--32 to 60 inches (81 to 152 cm); pink (7.5YR 7/4) and light brown (7.5YR 6/4) gravelly sandy loam, light brown (7.5YR 6/4) and brown (7.5YR 5/4) moist; massive; strongly weathered limestone and conglomerate; soft, very friable, slightly sticky and moderately plastic; few very fine and fine roots; many distinct calcium carbonate coatings on rock fragments; strongly weathered limestone and conglomerate; 30 percent gravel; violently effervescent, 42 percent calcium carbonate equivalent; moderately alkaline (pH 8.4).

TYPE LOCATION: Cochise County, Fort Huachuca, Arizona; located at a latitude of 31 degrees, 34 minutes, 25 seconds North and longitude of 110 degrees, 26 minutes, 30 seconds West.

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. Aridic ustic soil moisture regime.

Soil Temperature: 59 to 64 degrees F (15 to 17.8 degrees C).

Surface rock fragments: less than 55 percent
Rock fragments: less than 35 percent, but can range to 50 percent in any one horizon
Clay content: more than 35 percent in the control section
Effervescence: very slight to violent
Reaction: slightly acid to moderately alkaline
Depth to calcic horizon: 15 to 30 inches (38 to 76 cm)
Organic Matter content: 1 to 3 percent

A horizon
Hue: 7.5YR, 5YR
Value: 3 or 4 dry, 2 or 3 moist
Chroma: 1 to 4, dry or moist
Texture: sandy loam, loam, fine sandy loam, clay, clay loam

Bt horizon
Hue: 5YR, 2.5YR, 7.5YR
Value: 3 or 4 dry, 1 to 3 moist
Chroma: 2 to 6 dry, 1 to 4 moist
Texture: clay loam, clay, sandy clay

Btk horizon
Hue: 2.5YR, 5YR, 7.5YR
Value: 3 to 8, dry or moist
Chroma: 2 to 6, dry or moist
Texture: clay loam, sandy clay loam, clay
Calcium carbonate equivalent: 1 to 40 percent

Bk horizon
Hue: 7.5YR, 5YR
Value: 5 to 8 dry, 4 to 7 moist
Chroma: 2 to 4, dry or moist
Calcium carbonate equivalent: 30 to 45 percent
Texture: sandy loam, coarse sand, clay loam, loam

COMPETING SERIES: This is the Musquiz (TX) soils series. Musquiz soils have calcic horizon at depths of 30 to 50 inches.

GEOGRAPHIC SETTING: Blacktail soils are on fan remnants, side slopes, and pediments at elevations of 4,000 to 5,600 feet (1219 to 1707 meters). Slopes range from 1 to 60 percent. These soils formed in fan alluvium from mixed sources. The mean annual precipitation is 16 to 20 inches (406 to 508 mm) and occurs as thunderstorms during July to September and as gentle rains during December and January. The mean annual air temperature is 57 to 62 degrees F (13.9 to 16.7 degrees C). The frost-free period is 160 to 210 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Terrarossa, Pyeatt, Gardencan and Lanque soils. Terrarossa soils have an abrupt textural change. Pyeatt and Lanque soils do not have argillic horizons. Gardencan soils are fine-loamy.

DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; slow permeability.

USE AND VEGETATION: Used for livestock grazing, military training, recreation and wildlife habitat. Vegetation includes plains lovegrass, sideoats grama, Texas bluestem, crinkleawn, beggartick grass, cane beardgrass, false mesquite, velvet-pod mimosa, sotol, Palmer agave and yerbe-de-pasmo.

DISTRIBUTION AND EXTENT: Southern and Central Arizona. Blacktail soils are of moderate extent. MLRA 41 and zones in MLRA 38 that are adjacent to 41.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona

SERIES ESTABLISHED: Cochise County, Arizona; Soil survey of Cochise County, AZ, Douglas-Tombstone Part; 1996.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from 0 to 7 inches (0 to 18 cm)(A, Bt horizons)
Argillic horizon - the zone from 3 to 32 inches (8 to 81 cm)(Bt, Btk1, Btk3 horizons)
Calcic horizon - the zone from 17 to 60 inches (43 to 152 cm) (Btk2, Btk3, 2Bk horizons)

Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, 12th Edition, 2014

Updated competing series section 3/18/08, CEM

Revised for the correlation of AZ661 11/08, PDC

Revised for the correlation of Graham County, AZ, Southwestern Part; March, 2011, WWJ
Revised for the correlation of SDJR - MLRA 38 - Terrarossa-Blacktail Complex, 5 to 60 Percent Slopes; September, 2014, LJG2

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National Cooperative Soil Survey
U.S.A.