LOCATION ARIZO                   NV+AZ CA NM

Established Series
Rev. LNL/RPZ/ET
04/2015

ARIZO 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 180 millimeters (7 inches) and the mean annual temperature is about 17 degrees C. (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 20 centimeters (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 gravel; strongly effervescent; moderately alkaline (pH 8.2); abrupt wavy boundary. (0 to 25 centimeters thick)

Bk--20 to 91 centimeters (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 gravel, 10 percent cobbles; few very thin coats of calcium carbonate on undersides of gravel; strongly effervescent; moderately alkaline (pH 8.2); gradual wavy boundary.

C--91 to 157 centimeters (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 gravel, 20 percent cobbles, 3 percent stones; strongly effervescent; moderately alkaline (pH 8.2). (Combined thickness of the Bk and C horizons is 125 to 150 centimeters)

TYPE LOCATION: Clark County, Nevada; approximately 3.2 kilometers (2 miles) east and 1.6 kilometers (1 mile) north of Bunkerville, Nevada; about 305 meters (1,000 feet) east and 185 meters (600 feet) south of center of sec. 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 topographic quadrangle; UTM 11S 760513e 4075330n (DTM:NAD83).

RANGE IN CHARACTERISTICS:

Soil moisture control section: 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: 15 to 22 degreesC. (59 to 71 degrees F.).

Reaction: Neutral through 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, dominated by medium-sized gravel and larger fragments.

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:
Hue: 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 Dragonwash (T CA), Jean (NV), Kokan (NM), and Pipecan (T CA) series. Dragonwash soils are dominated by fine gravel (2 to 5 millimeters) within the particle size control section. 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. Pipecan soils are usually dry, moist following winter storms and only intermittingly moist near the soil surface following occasional summer convection storms.

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 225 to 1,405 meters (750 to 4,600 feet). The climate is arid or semiarid with mild winters and hot dry summers. The mean annual precipitation is 50 to 250 millimeters (2 to 10 inches) and may range to 330 millimeters (13 inches) in Arizona where temperatures are 19 to 21 degrees C. (67 to 70 degrees F.); mean annual temperature is 14 to 21 degrees C. (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 Bt2 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 SATURATED HYDRAULIC CONDUCTIVITY: Excessively drained; negligible to medium runoff; very high saturated hydraulic conductivity. Arizo soils with sandy loam and loam surface textures have moderately high to high saturated hydraulic conductivities.

USE AND VEGETATION: These soils are used for rangeland and wildlife habitat. The present vegetation is mainly creosote bush and burrobush.

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

SERIES ESTABLISHED: Clark County (Virgin River Area), Nevada. 1971.

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

Ochric epipedon - 0 to 18 centimeters (0 to 7 inches). (Part of the A horizon).
Particle-size control section - 25 to 100 centimeters (10 to 40 inches). (Part of the Bk and C horizons).

Responsibility for this series was transferred from Davis to Phoenix 4/2015. The last revision to the series was 4/2011. ET

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National Cooperative Soil Survey
U.S.A.