LOCATION FANNO AZEstablished Series
TAXONOMIC CLASS: Fine, illitic, mesic Aridic Haplustalfs
TYPICAL PEDON: Fanno gravelly clay loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 1 inch; dark reddish gray (5YR 4/2) gravelly light clay loam, dark reddish brown (5YR 3/4) moist; moderate fine granular structure; slightly hard, friable, sticky, plastic; many fine and very fine roots; many fine interstitial pores; 25 percent gravel; slightly acid (pH 6.5); clear wavy boundary. (1 to 6 inches thick)
Bt--1 to 8 inches; reddish brown (5YR 4/4) light clay, dark reddish brown (5YR 3/4) moist; weak fine and medium subangular blocky structure; hard, friable, sticky, plastic; many fine and very fine and few medium roots; common exped and common fine and very fine tubular pores; common thin clay films on faces of peds and in pores; common pressure faces; 5 percent gravel; neutral (pH 7.0); clear wavy boundary. (6 to 15 inches thick)
Bss--8 to 25 inches; reddish brown (5YR 4/4) clay, dark reddish brown (5YR 3/4) moist; moderate medium and coarse angular and subangular blocky structure; hard, friable, sticky, plastic; common fine and very fine and few medium roots; common fine and very fine tubular pores; common pressure faces; few small slickensides in lower part; slightly alkaline (pH 7.5); abrupt wavy boundary. (6 to 20 inches thick)
C--25 to 40 inches; weak red (2.5YR 4/2) weathered clayey shale, fractured in places, weak red (2.5YR 4/2) moist; massive; very hard, firm, slightly sticky, plastic; few fine roots in fractures; few pores; slightly effervescent; strongly effervescent on faces of fractures; moderately alkaline (pH 8.0).
TYPE LOCATION: Cochise County, Arizona; near Parker Canyon Lodge, Montezuma Pass road, north side of road, .45 mile east of Lochiel turnoff; approximately 1,100 feet south of N1/4 corner sec. 3, T.24S., R.19E.
RANGE IN CHARACTERISTICS:
Depth to the C horizon: 20 to 40 inches, but averages 22 to 36 inches.
Soil moisture: The driest period is the months of May and June. Aridic ustic moisture regime.
Mean annual soil temperature: 52 to 59 degrees F.
Calcium carbonate: Typically, these soils are noncalcareous in the A and upper B horizons, but are slightly calcareous throughout in some pedons.
A horizon
Reaction: slightly acid to moderately alkaline
Hue: 7.5YR through 2.5YR
Value: 5 or 4 dry
Chroma: 2 through 4
Rock fragments: few to 40 percent rock fragments and averages about 25 to 40 percent
B horizons
Hue: 5YR or 2.5YR
Value: 4 or 5 dry and 3 or 4 moist
Chroma: 3 through 6 dry and moist
Texture: mainly clay but includes heavy clay loam in the upper part
Reaction: neutral to moderately alkaline
The C horizon has a hardness of less than 3.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Fanno soils are on moderately sloping to moderately steep upland hills at elevations of 5,200 to 6,000 feet. Slopes are dominantly 5 to 12 percent but range up to 20 percent. These soils formed in residuum weathered from clayey shales, siltstones, and possibly sandstone. The average annual precipitation ranges from 14 to 18 inches. The mean annual temperature ranges from 50 to 57 degrees F. and the frost-free season ranges from 170 to 220 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Canelo, Faraway, Luzena, and Tortugas soils and the competing Casto and Martinez soils. Canelo soils are somewhat poorly drained and have more than 35 percent rock fragments in the control section. Faraway, Luzena, and Tortugas soils have mollic epipedons and have bedrock with a hardness of more than 3 at a depth of 20 inches or less.
DRAINAGE AND PERMEABILITY: Well-drained; medium runoff; slow permeability.
USE AND VEGETATION: These soils are used mainly for range and wildlife. Native vegetation is oak, juniper, and manzanita, curly mesquite, sideoats grama, blue and hairy grama, canebeardgrass, little bluestem, three-awn, purple and sprucetop grama, wolftail and Arizona cottontop.
DISTRIBUTION AND EXTENT: Cochise and Santa Cruz Counties, Arizona. These soils are inextensive. MLRA 41.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Santa Cruz County Area, Arizona, 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 1 inches (A horizon)
Argillic horizon - The zone from 1 to 8 inches (Bt horizon)
Classified according to Keys to Soil Taxonomy Tenth Edition, 2006
Classification changed from Udic subgroup to Aridic subgroup in 2006. This change was made to be consistent with the soil moisture regime.