LOCATION MOHON              AZ

MOHON SERIES

TAXONOMIC CLASS: Fine, smectitic, thermic Typic Calciargids

TYPICAL PEDON: Mohon very cobbly loam - rangeland. (Colors are for dry soil unless otherwise noted.)

A--0 to 2 inches; brown (7.5YR 5/4) very cobbly loam, dark brown (7.5YR 3/2) moist; moderate medium platy structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; 30 percent cobble and 15 percent gravel; slightly effervescent; slightly alkaline (pH 7.6); abrupt wavy boundary. (1 to 3 inches thick)

Bk--2 to 6 inches; strong brown (7.5YR 5/6) clay loam, strong brown (7.5YR 4/6) moist; weak medium subangular blocky structure; hard, firm, sticky and plastic; many very fine roots; many very fine tubular pores; strongly effervescent, 5 percent calcium carbonate equivalent; common fine soft calcium carbonate filaments; slightly alkaline (pH 7.8); clear wavy boundary. (0 to 5 inches thick)

Btk1--6 to 25 inches; strong brown (7.5YR 5/6) clay, brown (7.5YR 4/4) moist; strong medium prismatic structure; very hard, very firm, very sticky and very plastic; many very fine roots; many very fine tubular pores; few faint clay films on ped faces and in pores; 2 percent gravel; strongly effervescent, 10 percent calcium carbonate equivalent; few fine soft calcium carbonate masses; slightly alkaline (pH 7.8); clear wavy boundary. (15 to 36 inches thick)

Btk2--25 to 40 inches; strong brown (7.5YR 5/6) clay, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure; very hard, very firm, very sticky and very plastic; common fine roots; common fine tubular pores; common distinct clay films on ped faces and in pores; strongly effervescent, 15 percent calcium carbonate equivalent; 2 percent gravel; common medium soft calcium carbonate masses; moderately alkaline (pH 8.0); abrupt wavy boundary. (6 to 20 inches thick)

2Btk3--40 to 47 inches; pink (7.5YR 7/4) cobbly clay loam, light brown (7.5YR 6/4) moist; moderate medium subangular blocky structure; hard, firm, slightly sticky and plastic; few very fine roots; few very fine tubular pores; common faint clay films on ped faces and in pores; 10 percent cobble and 15 percent gravel; strongly effervescent, 20 percent calcium carbonate equivalent; common soft calcium carbonate masses; moderately alkaline (pH 8.4); gradual wavy boundary.

2Btk4--47 to 60 inches; pink (7.5YR 8/4) cobbly clay loam, pink (7.5YR 7/4) moist; moderate medium subangular blocky structure; hard, firm, slightly sticky and plastic; few very fine roots; few very fine tubular pores; few faint clay films on ped faces and in pores; 10 percent cobble and 20 percent gravel; violently effervescent, 25 percent calcium carbonate equivalent; many soft large calcium carbonate masses; moderately alkaline (8.4). (Combined thickness of the 2Btk horizons is 0 to 36 inches)

TYPE LOCATION: Mohave County, Arizona; latitude of 34 degrees, 58 minutes, 01 seconds north and a longitude of 114 degrees, 14 minutes, 35 seconds west; 260 feet south and 700 feet east of the northwest corner of section 07, T. 18 N., R. 18 W.
RANGE IN CHARACTERISTICS:

Soil moisture: Intermittently moist in some part of the soil moisture control section during December-February and for less than 20 days cumulative during July-September. Driest during May and June. Typic aridic soil moisture regime.

Soil Temperature: 61 to 72 degrees F.

Depth to calcic horizon: 20 to 40 inches

A horizon

Hue: 7.5YR, 5YR

Value: 5 or 6 dry, 3 through 5 moist

Chroma: 4 through 6, dry or moist

Btk horizons

Hue: 7.5YR, 5YR

Value: 5 or 6 dry, 4 or 5 moist

Chroma: 4 or 6, dry or moist

Texture: sandy clay loam, clay loam, sandy clay, clay, (averages 35 to 50 percent clay)

Rock fragments: 0 to 15 percent gravel

2Btk horizons

Hue: 10YR, 7.5YR

Value: 6 through 8 dry, 5 through 7 moist

Chroma: 4 through 6, dry or moist

Rock fragments: 15 to 35 percent cobble and gravel

COMPETING SERIES: There are no competing series at this time.

GEOGRAPHIC SETTING: Mohon soils are on fan terraces within the Mohave Desert. Slopes range from 2 to 15 percent. These soils formed in alluvium from volcanic rocks. Elevations range from 2,400 to 3,800 feet. The mean annual precipitation is 6 to 12 inches. The mean annual air temperature is 59 to 70 degrees F. The frost-free period is about 200 to 250 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cellar, Dudleyville, Kinley, Poachie, Stagecoach, Vekol and Vinton soils. Cellar soils are shallow to bedrock. Vekol soils do not have a calcic horizon. Kinley, Stagecoach and Poachie soils are loamy or loamy-skeletal. Dudleyville and Vinton soils are sandy-skeletal and sandy, respectively.

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

USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Vegetation includes big galleta, bush muhly, black grama, creosotebush, white bursage and flattop buckwheat.

DISTRIBUTION AND EXTENT: Northwestern Arizona. This series is of moderate extent. MLRA is 30. Name is from a local mountain range.

MLRA OFFICE RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Mohave County, Arizona; Soil survey of Mohave County, Arizona, Southern Part; 2005.

REMARKS: In 2005, the classification of the Mohon Series was changed to reflect the presence of a calcic horizon.

Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - The zone from 0 to 2 inches (A horizon)

Argillic horizon - The zone from 6 to 60 inches (Btk1, Btk2, 2Btk3, 2Btk4 horizons)

Calcic horizon - The zone from 25 to 60 inches (Btk2, 2Btk3, 2Btk4 horizons)

Classified according to Keys to Soil Taxonomy Ninth Edition, 2003