LOCATION HICKIWAN AZEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, hyperthermic, shallow Calcic Petrocalcids
TYPICAL PEDON: Hickiwan very gravelly sandy loam - rangeland (colors are for dry soil unless otherwise noted).
A--0 to 2 inches; light brown (7.5YR 6/4) very gravelly sandy loam, brown (7.5YR 4/4) moist; weak thin platy structure; slightly hard, very friable, nonsticky and slightly plastic; common fine roots; common very fine vesicular pores; 42 percent gravel; strongly effervescent; moderately alkaline (pH 8.4); abrupt smooth boundary (1 to 2 inches thick).
Bk--2 to 14 inches; light brown (7.5YR 6/4) very gravelly sandy loam, brown (7.5YR 4/4) moist; massive; slightly hard, very friable, nonsticky and slightly plastic; common fine roots; common fine tubular pores; 45 percent gravel; many distinct continuous calcium carbonate coatings on rock fragments; violently effervescent; moderately alkaline (pH 8.4); abrupt wavy boundary (4 to 18 inches thick).
2Bkm--14 to 60 inches; indurated petrocalcic; extremely hard.
TYPE LOCATION: Pima County, Arizona; latitude of 32 degrees, 37 minutes, 17 seconds North and longitude of 111 degrees, 47 minutes, 46 seconds West and 1060 feet West and 450 feet South of the Northeast corner of Section 25, T. 9 S., R. 5 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
A horizon
Hue: 7.5YR, 10YR
Value: 4 or 7 dry, 3 or 5 moist
Chroma: 2 through 5, dry or moist
Calcium carbonate equivalent: 0 to 13 percent
Bk horizon
Hue: 7.5YR, 10YR
Value: 4 to 7 dry, 3 to 6 moist
Chroma: 2 through 5, dry or moist
Texture: sandy loam, loam, fine sandy loam
Calcium carbonate equivalent: 13 to 40 percent
Bkm horizon
Cementation: Indurated or strongly cemented with calcium carbonate
COMPETING SERIES: This is the Cheosa (TX), Guvo (AZ) and Ojinaga (T)(TX) series. Guvo soils have bedrock at moderate depths below the hardpan. Ojinaga soils have sand and gravel below the petrocalcic horizon. Cheosa soils are in the ustic aridic soil moisture regime.
GEOGRAPHIC SETTING: The Hickiwan soils are on relict fan terraces and fan terraces. Slope ranges from 1 to 20 percent. These soils formed from mixed fan alluvium derived dominantly from basalt, andesite and conglomerate. Elevations range from 1400 to 2200 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 240 to 325 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.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderately rapid permeability.
USE AND VEGETATION: Hickiwan soils are used for livestock grazing and wildlife habitat. Vegetation includes creosotebush, cacti, bush muhly, ocotillo, triangle bursage, and white ratany.
DISTRIBUTION AND EXTENT: Southern Arizona. This series is of moderate extent. MLRA is 40. Hickiwan is a village on the Tohono O'odham Nation.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Pinal County, Arizona; Soil survey of Tohono O'odham Indian Reservation, 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 2 inches (A horizon)
Calcic horizon - the zone from 2 to 14 inches (Bk horizon)
Petrocalcic horizon - the zone from 14 to 60 inches (Bkm horizon)
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Tenth Edition, 2006
Updated Competing Series Section 6/9/08, CEM
Revised for the correlation of AZ661, 2/2009, WWJ