LOCATION MOHON AZ

Established Series
Rev. WJ/PDC/RKS/HCD
11/2015

MOHON SERIES

The Mohon series consists of very deep, well drained soils that formed in alluvium from volcanic rocks. Mohon soils are on fan terraces with slopes of 2 to 15 percent. The mean annual precipitation is about 9 inches and the mean annual air temperature is about 64 degrees F.

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 SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: PHOENIX, ARIZONA

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

Responsibility for this series was transferred from Davis to Phoenix 11/2015. The last revision to the series was 6/2005. ET

National Cooperative Soil Survey
U.S.A.