LOCATION ARIZO NV AZ CA NMEstablished Series
The Arizo series consists of very deep, excessively drained soils that formed in mixed alluvium. Arizo soils are on recent alluvial fans, inset fans, fan apron, fan skirts, stream terraces, floodplains of intermittent streams and channels. Slope ranges from 0 to 15 percent. The mean annual precipitation is about 7 inches and the mean annual temperature is about 62 degrees F.
TAXONOMIC CLASS: Sandy-skeletal, mixed, thermic Typic Torriorthents
TYPICAL PEDON: Arizo very gravelly fine sand, desert wildlife habitat. (Colors are for dry soil unless otherwise noted.)
A--0 to 8 inches; light brownish gray (10YR 6/2) very gravelly fine sand, dark grayish brown (10YR 4/2) moist; weak coarse platy structure; slightly hard, very friable, nonsticky and nonplastic; few fine and medium roots; few fine vesicular and many very fine and fine interstitial pores; 35 percent pebbles; strongly effervescent; moderately alkaline (pH 8.2); abrupt wavy boundary. (0 to 10 inches thick)
Bk--8 to 36 inches; light brownish gray (10YR 6/2) extremely gravelly sand, dark grayish brown (10YR 4/2) moist; single grained; loose, nonsticky and nonplastic; few fine and medium roots; many very fine and fine interstitial pores; 60 percent pebbles and 10 percent cobbles; few very thin coats of calcium carbonate on undersides of pebbles; strongly effervescent; moderately alkaline (pH 8.2); gradual wavy boundary.
C--36 to 62 inches; light brownish gray (10YR 6/2) extremely gravelly sand, dark grayish brown (10YR 4/2) moist; single grained; loose, nonsticky and nonplastic; few very fine and fine roots; many very fine and fine, and few medium interstitial pores; 60 percent pebbles, 20 percent cobbles and 3 percent stones; strongly effervescent; moderately alkaline (pH 8.2). (Combined thickness of the Bk and C horizons is 50 to 60 inches)
TYPE LOCATION: Clark County, Nevada; approximately 2 miles east and 1 mile north of Bunkerville, Nevada; about 1,000 feet east and 600 feet south of center of section 20, T. 13 S., R. 71 E. 36 degrees, 47 minutes, 16.8 seconds north latitude and 114 degrees, 4 minutes, 50.0 seconds west longitude; USGS Mesquite, NV-AZ 7.5 minute quadrangle; UTM 11S, 760513e 4075330n; NAD83.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually dry, moist for short periods throughout the moisture control section during December through March. Moist above and periodically in upper part of moisture control section for 10 to 20 days cumulative, during July through October. The soil has a typic aridic soil moisture regime.
Soil temperature - 59 to 71 degrees F.
Reaction: Neutral to strongly alkaline.
Other features: Effervescent in some or all parts, with thin calcium carbonate coatings on undersides of rock fragments in some pedons.
Control section - Rock fragments: 35 to 85 percent.
A horizon - Hue: 10YR or 7.5YR.
Value: 5 through 8 dry, 3 through 6 moist.
Chroma: 2 through 6.
Bk and/or C horizons - 10YR or 7.5YR.
Value: 4 through 8 dry, 3 through 6 moist.
Chroma: 2 through 6.
Texture: Averages coarse sand through loamy sand.
Structure: Single grained or massive.
COMPETING SERIES: These are the Dudleyville (AZ), Jean (NV) and Kokan (NM) series. Dudleyville soils occur within the Sonoran Desert (MLRA 40 and 41) and are moist above and periodically in upper part of moisture control section for more than 20 days cumulative, during July through October. Jean soils have a shallow Bw horizon and have textures in the upper control section of loamy sand or loamy fine sand with less than 15 percent rock fragments. Kokan soils occur within the Chihuahuan Desert (MLRA 42) and are moist for short periods in some part mainly in July, August, and early September and are dry the rest of the year.
GEOGRAPHIC SETTING: Arizo soils are on recent alluvial fans, inset fans, fan aprons, fan skirts, stream terraces, floodplains of intermittent streams and channels. These soils form in mixed alluvium. Slope ranges from 0 to 15 percent. Elevations are 750 to 4,600 feet. The climate is arid or semiarid with mild winters and hot dry summers. The mean annual precipitation is 2 to 10 inches and may range to 13 inches in Arizona where temperatures are 67 to 70 degrees F.; mean annual temperature is 57 to 70 degrees F., and the frost-free season is 180 to 340 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bard, Bitter Spring, Gila, Nickel, Tonopah, and Vinton soils. Bard soils have a petrocalcic horizon. Bitter Spring soils have a gravelly sandy loam B2t horizon. Gila soils have a loamy control section. Nickel and Tonopah soils have a calcic horizon. Vinton soils have a loamy fine sand or loamy sand control section.
DRAINAGE AND PERMEABILITY: Excessively drained; negligible to medium runoff; rapid to very rapid permeability. Arizo soils with sandy loam and loam surface textures have moderate or moderately rapid over very rapid permeability.
USE AND VEGETATION: These soils are used for rangeland and wildlife habitat. The present vegetation is mainly creosotebush and white bursage.
DISTRIBUTION AND EXTENT: Southern Nevada, Southern California, Arizona, and New Mexico. These soils are extensive. The central concept for the series is in MLRA 30. Use in MLRA 40, 41, 42 should be reevaluated.
MLRA OFFICE RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Clark County (Virgin River Area), Nevada. 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 8 inches (A horizon).
Particle-size control section -10 to 40 inches (Part of the Bk and C horizons).