LOCATION GUVO AZEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, hyperthermic, shallow Calcic Petrocalcids
TYPICAL PEDON: Guvo very cobbly fine sandy loam - rangeland (colors are for dry soil unless otherwise noted).
A--0 to 1 inch; brown (7.5YR 5/4) very cobbly fine sandy loam, reddish yellow (7.5YR 6/6) moist; weak coarse platy structure; soft, friable, slightly sticky and nonplastic; common very fine roots; common fine tubular pores; very few distinct continuous calcium carbonate coatings on rock fragments; 20 percent cobble, 37 percent gravel; slightly effervescent; slightly alkaline (pH 7.8); abrupt wavy boundary (1 to 2 inches thick).
Bk1--1 to 8 inches; brown (7.5YR 5/4) very cobbly loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; soft, very friable, moderately sticky and moderately plastic; common very fine roots; common fine tubular pores; few distinct continuous calcium carbonate coatings on rock fragments; 40 percent cobble, 15 percent gravel; slightly effervescent; slightly alkaline (pH 7.8); abrupt wavy boundary.
Bk2--8 to 18 inches; brown (7.5YR 5/4) very cobbly loam, brown (7.5YR 4/4) moist; massive; soft, very friable, moderately sticky and moderately plastic; common fine roots; common fine tubular pores; many distinct continuous calcium carbonate coatings on rock fragments; 50 percent cobble; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary (combined thickness of the Bk horizons is 4 to 16 inches).
2Bkm--18 to 24 inches; indurated petrocalcic; extremely hard (1 to 15 inches thick).
3R--24 inches; basalt.
TYPE LOCATION: Pinal County, Arizona; latitude of 32 degrees, 45 minutes, 6 seconds North and a longitude of 111 degrees, 57 minutes, 44 seconds West and 600 feet East and 600 feet South of the Northwest corner of Section 9, T. 8 S., R. 4 E.
RANGE IN CHARACTERISTICS:
Soil moisture: Intermittently moist in some part of the soil moisture control section during July - September and December - February. Driest during May and June. Typic aridic soil moisture regime.
Soil temperature: 72 to 75 degrees F.
Rock fragments: 35 to 60 percent gravel, cobble and/or hardpan fragments
Reaction: slightly to moderately alkaline
Clay content: ranges from 8 to 25 percent; averages less than 18 percent in the control section
Depth to petrocalcic: 5 to 20 inches
Depth to bedrock: 6 to 35 inches
A horizon
Hue: 7.5YR, 10YR
Value: 5 or 6 dry, 4 through 6 moist
Chroma: 3 or 4 dry, 4 through 6 moist
Calcium carbonate equivalent: 0 to 13 percent
Bk or Bw horizon
Hue: 7.5YR, 10YR
Value: 5 through 8 dry, 5 through 7 moist
Chroma: 2 through 4, dry or moist
Texture: sandy loam, loam, fine sandy loam
Calcium carbonate equivalent: 13 to 40 percent
Bkm horizon
Cementation: Indurated or strongly cemented by calcium carbonate
COMPETING SERIES: These are the Cheosa (TX), Hickiwan (AZ) and Ojinaga (T) (TX) series. Hickiwan and Ojinaga soils do not have bedrock below the hardpan. Cheosa soils are in the ustic aridic soil moisture regime.
GEOGRAPHIC SETTING: The Guvo soils are on hills. Slope ranges from 10 to 25 percent. These soils formed in mixed slope alluvium dominantly from basalt. Elevations ranges from 1400 to 2500 feet. The mean annual precipitation is 7 to 10 inches. The mean annual air temperature is 70 to 73 degrees F. The frost-free period is 250 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hyder, Gachado, Momoli, Gunsight, Carrizo, Ajo and Pinamt soils. Momoli, Gunsight, Carrizo, and Pinamt soils are very deep. Gachado, Ajo and Pinamt soils have argillic horizons. Hyder soils do not have a petrocalcic horizon above the bedrock.
DRAINAGE AND PERMEABILITY: Well drained, medium to rapid runoff; moderate permeability.
USE AND VEGETATION: Guvo soils are used for livestock grazing and wildlife habitat. Vegetation includes creosotebush, cacti, bush muhly, ocotillo, triangle bursage and paloverde.
DISTRIBUTION AND EXTENT: Southern Arizona. This series is of moderate extent. MLRA is 40.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Maricopa County, Arizona; Soil survey of Tohono O'odham Nation, AZ, Parts of Maricopa, Pima and Pinal Counties; 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 1 inch (A horizon)
Calcic horizon - the zone from 1 to 18 inches (Bk1, Bk2 horizons)
Petrocalcic horizon - the zone from 18 to 24 inches (Bkm horizon)
Lithic contact - the boundary at 24 inches (3R horizon)
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Tenth Edition, 2006.
Updated Competing Series Section 6/9/08, CEM