LOCATION FERNO                   AZ

Established Series
Rev. JMH/CF/MJA
02/2025

FERNO SERIES

The Ferno series consists of moderately deep, well drained soils that formed in colluvium and/or residuum derived from basalt. Ferno soils are on footslopes of hills and relict faults. Slopes range from 2 to 23 percent. Mean annual precipitation is about 16 inches and the mean annual temperature is about 50 degrees F.

TAXONOMIC CLASS: Clayey-skeletal, mixed, superactive, mesic Aridic Haplustalfs

TYPICAL PEDON: Thunderbird-Ferno complex (Colors are for dry soil unless otherwise noted.)

A--0 to 3 inches (0 to 7 cm); brown (10YR 4/3) cobbly loam, dark brown (7.5YR 3/2) moist; moderate fine subangular blocky; moderately hard, friable, slightly sticky, slightly plastic; few very fine and fine dendritic tubular pores; common very fine and few fine roots throughout; 10 percent gravel; noneffervescent; slightly alkaline (pH 7.8); clear smooth boundary

Bt1--3 to 11 inches (7 to 27 cm); brown (7.5YR 4/3) flaggy loam, dark brown (7.5YR 3/4) moist; moderate fine angular blocky; hard, friable, slightly sticky, slightly plastic; few very fine, fine, and medium dendritic tubular pores; few very fine and common fine roots throughout , and common coarse roots in cracks; 15 percent faint clay films on top faces of peds; 15 percent flagstones, 20 percent channers, 10 percent cobbles, and 10 percent gravel; noneffervescent; slightly alkaline (pH 7.8); clear irregular boundary

Bt2--11 to 20 inches (27 to 52 cm); dark reddish brown (5YR 3/4) cobbly sandy clay loam, dark brown (7.5YR 3/4) moist; structureless massive; hard, firm, moderately sticky, moderately plastic; 10 percent flagstones, 15 percent channers, 15 percent cobbles, 35 percent distinct pressure faces on all faces of peds; 10 percent gravel; noneffervescent; slightly alkaline (pH 7.7); abrupt wavy boundary

R--20 to 30 inches (52 to 77 cm); basalt bedrock

TYPE LOCATION: Coconino County, Arizona; located about 17.9 kilometers (11.1 miles) northeast of Perkinsville, Arizona; USGS Quadrangle May Tank Pocket; Latitude 35.043328, Longitude -112.132920, Datum WGS84.

RANGE IN CHARACTERISTICS:
Soil moisture regime: ustic bordering on aridic
Mean annual soil temperature: 48 to 52 degrees F
Rock fragment content: 35 to 60 percent
Depth to lithic contact: 9 to 20 inches
Particle-size control section:
Clay content: 20 to 32 percent

A horizon
Hue: 7.5YR or 10YR
Value: 4 or 5 (3 or 4 moist)
Chroma: 2 or 3, dry or moist
Calcium carbonate equivalent: 0 to 2 percent
Reaction: slightly alkaline or moderately alkaline

Bt horizons
Hue: 7.5YR or 10YR
Value: 4 or 5 (3 or 4 moist)
Chroma: 3 or 4, dry or moist
Texture: loam or sandy clay loam
Calcium carbonate equivalent: 0 to 2 percent
Sodium Adsorption Ratio (SAR): 0 to 2
Reaction: slightly alkaline or moderately alkaline

COMPETING SERIES: These are the Cochiti, Devisadero, Patos, and Sabroso soils. Cochiti, Devisadero, Patos, and Sabroso soils are more frequently moist in spring, and reside in Eastern New Mexico.

GEOGRAPHIC SETTING:
Parent material: colluvium or residuum from basalt
Landform: footslopes of hills
Slopes: 2 to 23 percent
Elevation: 6,200 to 7,400 feet
Mean annual air temperature: 43 to 49 degrees F
Mean annual precipitation: 14 to 18 inches
Precipitation peaks in July and August, and in winter months. May and June are much drier.
Frost-free period: 120 to 140 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Thunderbird and, Grandwash soils. Thunderbird soils are on toeslopes and viscous lava fields of basalt. Grandwash soils are shallow to bedrock adjacent to canyons.

DRAINAGE AND PERMEABILITY: well drained, slow permeability

USE AND VEGETATION: These soils are used principally as grazing land. Native vegetation is mainly ponderosa pine, Gambel oak, muttongrass, and alligator juniper.

DISTRIBUTION AND EXTENT: Northern Arizona. MLRA 39.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.

SERIES ESTABLISHED: Coconino County, Arizona.

REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: from 0 to 7 centimeters. (A horizon)
Argillic horizon: from 7 to 52 centimeters. (Bt horizons)
Name is derived from Ferno Mesa
Taxonomic Version: Keys to Soil Taxonomy, Thirteenth Edition, 2022

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National Cooperative Soil Survey
U.S.A.