Established Series


The Luzena series consists of shallow and very shallow, well drained soils that formed in alluvium, residuum and colluvium from volcanic rock. Luzena soils are on mesas, hills and mountains and have slopes of 2 to 60 percent. The mean annual precipitation is about 16 inches and the mean annual air temperature is about 54 degrees F.

TAXONOMIC CLASS: Clayey, smectitic, mesic Aridic Lithic Argiustolls

TYPICAL PEDON: Luzena very gravelly clay - rangeland. (Colors are for dry soil unless otherwise noted.)

A--0 to 1 inch; dark reddish gray (5YR 4/2) very gravelly clay, dark reddish brown (5YR 3/2) moist; weak thin platy structure; slightly hard, friable, sticky and plastic; common very fine and few fine roots; many very fine and fine tubular and irregular pores; 40 percent gravel and 10 percent cobble; moderately acid (pH 6.0); clear smooth boundary. (1 to 4 inches thick)

Bt--1 to 8 inches; dark reddish brown (5YR 3/2) gravelly clay, dark reddish brown (5YR 2/2) moist; moderate medium angular blocky structure; hard, firm, very sticky and very plastic; common very fine and fine and few medium roots; few very fine and fine tubular pores; 20 percent gravel; neutral (pH 6.8); abrupt irregular boundary. (4 to 18 inches thick)

2R--8 inches; andesite.

TYPE LOCATION: Greenlee County, Arizona; about 5 miles north of Morenci; 800 feet east and 1100 feet south of the northwest corner of Section 28, T. 3 S., R. 29 E.

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.

Rock fragments: 15 to 35 percent

Soil temperature: 50 to 59 degrees F.

Depth to bedrock: 7 to 20 inches. Some pedons contain a layer of weathered bedrock, paralithic contact, less than 3 inches thick above the lithic contact.

Reaction: Moderately acid to moderately alkaline

A horizon
Hue: 5YR, 7.5YR, 10YR
Value: 3 to 5 dry, 2, 2.5 or 3 moist
Chroma: 2 or 3, dry or moist

Bt or Btss (if present) horizons
Hue: 5YR, 7.5YR
Value: 3 to 5 dry, 2, 2.5 or 3 moist
Chroma: 2 or 3, dry or moist
Texture: Clay, silty clay, clay loam, silty clay loam (35 to 60 percent clay)
Some pedons contain accumulations of calcium carbonate at the soil rock interface.

COMPETING SERIES: These are the Cabezon (NM) and Cross (AZ) series. Cabezon soils formed in eolian material over residuum derived from basalt. Cross soils have Bk horizons.

GEOGRAPHIC SETTING: Luzena soils are on mesas, hills and mountains and have slopes of 2 to 60 percent. These soils formed in alluvium, colluvium and residuum from andesite, rhyolite, tuff and volcanic breccia. Elevations range from 4,000 to 6,800 feet. The mean annual precipitation is 13 to 18 inches. The mean annual air temperature is 48 to 57 degrees F. The frost-free period is 130 to 220 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Faraway and Lynx soils. These soils do not have an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; medium to high runoff; slow permeability.

USE AND VEGETATION: Luzena soils are used for livestock grazing and wildlife habitat. The present vegetation is blue grama, hairy grama, black grama, sideoats grama, and slender grama, curly mesquite, plains lovegrass, cane bluestem, wooly bunchgrass, Emory oak and juniper.

DISTRIBUTION AND EXTENT: Arizona and New Mexico. This series is extensive. MLRA 35, 38, 41.


SERIES ESTABLISHED: Gila Project, Arizona, Soil Conservation Service; 1936.

Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from 0 to 8 inches (A, Bt horizons)
Argillic horizon - The zone from 1 to 8 inches (Bt horizon)
Lithic contact - The boundary at 8 inches (2R horizon)

The series was reclassified and the competing series section was updated in October, 2004, to reflect changes in the Keys to Soil Taxonomy, Ninth Edition, 2003.

National Cooperative Soil Survey