LOCATION GUEST                   AZ

Established Series


The Guest series consists of very deep, well drained soils that formed in alluvium from mixed sources. Guest soils are on flood plains and alluvial fans and have slopes of 0 to 5 percent. The mean annual precipitation is about 14 inches and the mean annual air temperature is about 63 degrees F.

TAXONOMIC CLASS: Fine, mixed, superactive, calcareous, thermic Ustertic Torrifluvents

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

A--0 to 10 inches; brown (10YR 5/3) clay, dark brown (7.5YR 3/2) moist; weak fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; many very fine and fine roots; few very fine irregular and tubular pores; violently effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (8 to 14 inches thick)

Ck1--10 to 28 inches; brown (10YR 5/3) clay, dark brown (10YR 3/3) moist; weak fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common fine and medium roots; few very fine irregular and tubular pores; few fine gravel; violently effervescent as few fine filaments of calcium carbonate; moderately alkaline (pH 8.2); clear smooth boundary. (14 to 30 inches thick)

Ck2--28 to 62 inches; grayish brown (10YR 5/2) clay, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; few fine roots; few very fine irregular and tubular pores; violently effervescent as common fine filaments of calcium carbonate; moderately alkaline (pH 8.2).

TYPE LOCATION: Yavapai County, Arizona; Approximately 2,000 feet south and 1,300 feet east of the northwest corner of section 20, T.14 N., R.6 E.


Soil moisture: Intermittently moist in some part of the soil moisture control section during July-September and December-February. The epipedon is moist in some part less than 90 days (cumulative) when the soil temperature is above 41 degrees F. in 7 out of 10 years. Driest during May and June. Ustic aridic soil moisture regime.

Soil cracking: When dry, cracks 1 cm or more wide, extend to depths of 20 inches or more and remain open for 175 to 240 days and are not closed for 60 days. Pressure faces are common in some pedons.

Rock fragments: ranges from 0 to 20 percent gravel; averages less than 15 percent in the control section

Reaction: Slightly to strongly alkaline

Salinity: Nonsaline to strongly saline

Gypsum: 0 to 4 percent as crystals or common filaments

Calcium carbonate: disseminated or occurs as fine filaments

Organic matter: greater than 1 percent decreasing irregularly with depth

A and C horizons
Hue: 7.5YR, 10YR
Value: 3, through 6 dry, 2 through 6 moist
Chroma: 1 through 6, dry or moist
Texture: silty clay, silty clay loam, clay loam, clay (35 to 60 percent clay)
Stratification: less than 2 inch thick strata of coarser material is common

Some pedons contain horizons with redder hue and textures of sandy clay loam or sandy clay at depths greater than 40 inches.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Guest soils are on floodplains and alluvial fans at elevations of 2,200 to 5,500 feet. Slopes are dominantly 0 to 2 percent and range from 0 to 5 percent. The soils formed in mixed fine textured sediments derived from acid and basic igneous rocks. The mean annual air temperature ranges from 57 to 70 degrees F. Mean annual precipitation is 12 to 16 inches that falls as summer thunderstorms and gentle winter rains. The frost-free period ranges from 170 to 280 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Comoro and Ubik soils. Comoro and Ubik soils are coarse-loamy.

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

USE AND VEGETATION: These soils are used for livestock grazing and irrigated cropland. Crops are alfalfa, small grains, and pasture. Vegetation is mesquite, creosotebush, catclaw, salt cedar, tobosa grass, and annuals. Some areas are nearly barren, but in other places the growth of tobosa is sufficient to give the appearance of small "tobosa flats".

DISTRIBUTION AND EXTENT: Central and southern Arizona. This soil is moderately extensive. This soil occurs in LRR-D, MLRAs 38, 40, 41, and 42.


SERIES ESTABLISHED: Yavapai County (Beaver Creek Area), Arizona; 1965.

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

Ochric epipedon - the zone from 0 to 10 inches (A horizon)

Entisol feature - the absence of diagnostic subsurface horizons

Fluvial feature - irregular decrease in organic carbon in the zone from 10 to 62 inches (Ck1, Ck2 horizons)

Ustertic feature - soil cracks

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

Revised for the correlation of Graham County, AZ, Southwestern Part; March, 2011, WWJ

National Cooperative Soil Survey