LOCATION NAVAJO                  AZ+NM UT

Established Series


The Navajo series consists of very deep, well drained soils that formed in mixed alluvium. Navajo soils are on flood plains, alluvial fans and playas. Slopes are 0 to 5 percent. Mean annual precipitation is about 9 inches and the mean annual air temperature is about 52 degrees F.

TAXONOMIC CLASS: Fine, mixed, superactive, calcareous, mesic Vertic Torrifluvents

TYPICAL PEDON: Navajo silty clay - rangeland. (Colors are for dry soil unless otherwise noted.)

A--0 to 5 inches; reddish brown (5YR 5/3) silty clay, reddish brown (5YR 4/3) moist; weak medium and thick platy structure; hard, firm, very sticky and very plastic; few fine tubular and many fine irregular pores; strongly effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (2 to 14 inches thick)

C--5 to 20 inches; reddish brown (2.5YR 4/4) silty clay, dark reddish brown (2.5YR 3/4) moist; weak medium and coarse angular blocky structure; very hard, very firm, very sticky and very plastic; few fine tubular and many fine irregular pores; few pressure faces; strongly effervescent; moderately alkaline (pH 8.0); gradual smooth boundary. (12 to 20 inches thick)

Css--20 to 60 inches; reddish brown (2.5YR 4/4) stratified clay, dark reddish brown (2.5YR 3/4) moist; massive; very hard, very firm, very sticky and very plastic; few fine tubular and many fine irregular pores; few small slickensides and pressure faces; common fine calcium carbonate filaments and masses; strongly effervescent; moderately alkaline (pH 8.0).

TYPE LOCATION: Navajo County, Arizona; about 6 miles northwest of Winslow; 1320 feet east and 50 feet north of the southwest corner of section 23, T. 20 N., R. 15 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. Typic aridic soil moisture regime.

Organic matter - Less than 1 percent

Calcium carbonate - Disseminated or segregated in masses; calcium carbonate equivalent is less than 10 percent

Reaction: slightly alkaline to very strongly alkaline

Cracking: 1 cm or more at 50 cm

Slickensides: Few to common

A horizon
Hue: 10YR, 7.5YR, 5YR, 2.5YR
Value: 4 to 6 dry, 3 to 5 moist
Chroma: 3 to 6 dry, 3 or 4 moist
Reaction: slightly alkaline to very strongly alkaline

C horizons
Hue: 10YR, 7.5, 5YR, 2.5YR
Value: 3 to 6, dry or moist
Chroma: 2 to 6, dry or moist
Texture: silty clay, clay, clay loam, silty clay loam; averages 35 to 60 percent clay in the particle size control section; some pedons have strata of finer or coarser textures.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Navajo soils are on alluvial fans, flood plains, and playas and have slopes of 0 to 5 percent. Elevations are 4,500 to 6,800 feet. The soils formed in mixed alluvium from basalt, shale, pyroclastics and sandstone. The mean annual precipitation is 6 to 10 inches occurring as thunderstorms in summer and as gentle rain or snow in winter. The mean annual air temperature ranges from 47 to 57 degrees F. The frost-free period is 120 to 180 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Claysprings, Epikom, Rune, Tours, and Winona soils. Claysprings, Epikom, and Winona soils are shallow to bedrock. Tours soils are fine-silty. Rune soils have a mollic epipedon.

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

USE AND VEGETATION: These soils are used for livestock grazing, wildlife habitat and irrigated cropland. Irrigated areas produce alfalfa, small grains and pasture. Native vegetation is sparse stands of western wheatgrass, blue grama, sand dropseed, galleta, alkali sacaton, fourwing saltbush and fine mesquite.

DISTRIBUTION AND EXTENT: Northeastern Arizona, northwestern New Mexico and southeastern Utah. The series is moderately extensive. MLRAs 35 & 36.


SERIES ESTABLISHED: Winslow area, Arizona; 1921.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - The zone from 0 to 5 inches (A horizon)

Entisol feature - The absence of diagnostic subsurface horizons

Classified according to Soil Taxonomy Second Edition, 1999; Keys to Soil Taxonomy Eleventh Edition, 2010

Update and revisions for the correlation of Little Colorado River Area (AZ707), Sept. 2011, CEM

National Cooperative Soil Survey