LOCATION SHONTIK AZEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, hyperthermic Sodic Haplocalcids
TYPICAL PEDON: Shontik fine sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 1 inch; light yellowish brown (10YR 6/4) fine sandy loam, dark yellowish brown (10YR 4/4) moist; weak very thin platy structure; soft, very friable, nonsticky and nonplastic; many very fine roots; many very fine tubular pores; strongly effervescent; very slightly saline (ECe 2 dS/m) and slightly sodic (SAR 1); moderately alkaline (pH 8.2); abrupt smooth boundary. (1 to 5 inches thick)
Anz--1 to 9 inches; light yellowish brown (10YR 6/4) fine sandy loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine roots; many very fine tubular pores; violently effervescent; slightly saline (ECe 7 dS/m) and moderately sodic (SAR 24); moderately alkaline (pH 8.2); clear smooth boundary. (0 to 8 inches thick)
Bwn1--9 to 16 inches; reddish yellow (7.5YR 6/6) fine sandy loam, strong brown (7.5YR 4/6) moist; moderate fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; few fine roots; many very fine tubular pores; violently effervescent; strongly saline (ECe 20 dS/m) and strongly sodic (SAR 50); very strongly alkaline (pH 9.6); clear smooth boundary. (5 to 22 inches thick)
Bwn2--16 to 28 inches; reddish yellow (7.5YR 6/6) fine sandy loam, strong brown (7.5YR 4/6) moist; weak coarse prismatic structure parting to moderate medium subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; many very fine tubular pores; common fine, irregular, soft accumulations of lime and salt; violently effervescent; strongly saline (ECe 20 dS/m) and strongly sodic (SAR 80); very strongly alkaline (pH 9.6); clear wavy boundary. (0 to 12 inches thick)
2Btknzb1--28 to 34 inches; light reddish brown (5YR 6/4) clay loam, brown (7.5YR 5/4) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, very sticky and plastic; few very fine roots; many very fine tubular pores; common distinct colloidal stains on mineral grains; many fine and medium, rounded, soft accumulations of lime; violently effervescent; strongly saline (ECe 20 dS/m) and strongly sodic (SAR 74); very strongly alkaline (pH 9.4); clear wavy boundary.
2Btknzb2--34 to 50 inches; light reddish brown (5YR 6/4) sandy clay loam, brown (7.5YR 4/4) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, very sticky and plastic; few very fine roots; many very fine tubular pores; common distinct colloidal stains and few distinct clay films bridging mineral grains; many fine and medium, rounded, soft accumulations of lime; violently effervescent; strongly saline (ECe 26 dS/m) and strongly sodic (SAR 74); very strongly alkaline (pH 9.4); abrupt smooth boundary.
2Btknzb3--50 to 60 inches; light brown (7.5YR 6/4) sandy clay loam, brown (7.5YR 4/4) moist; moderate fine and medium subangular blocky structure; hard, very friable, very sticky and very plastic; many very fine tubular pores; few distinct clay films bridging mineral grains; many medium, rounded, soft accumulations of lime; violently effervescent; strongly saline (ECe 23 dS/m) and strongly sodic (SAR 76); very strongly alkaline (pH 9.4). (Combined thickness of the Bt horizons is 21 to 39 inches)
TYPE LOCATION: Pinal County, Arizona; about 3 miles north of Pima Butte, on the Gila River Indian Reservation; 200 feet north and 1500 feet west of the southeast center of section 3, T. 3 S., R. 3 E.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually dry, intermittently moist in some part of the soil moisture control section during July-September and December-February. Typic aridic moisture regime.
Depth to buried argillic horizon - 20 to 40 inches.
The sodium adsorption ratio exceeds 45 throughout the control section.
The 10 to 40 inch particle size control section averages more then 18 percent clay.
Rock fragments - 0 to 50 percent in any one horizon; averages less than 35 percent in the particle size control section.
Salinity- Nonsaline to strongly saline.
Sodicity- Slightly sodic to strongly sodic.
Carbonates- Noneffervescent to violently effervescent in the upper part; strongly or violently effervescent in the lower part.
A horizon
Hue: 10YR or 7.5YR.
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 3, 4 or 6, dry and moist.
Reaction: Mildly alkaline to very strongly alkaline.
B horizon
Hue: 10YR or 7.5YR.
Value: 5, 6 or 7 dry, 3, 4 or 5 moist.
Chroma: 4 or 6 dry and moist.
Texture: Fine sandy loam, sandy loam, sandy clay loam (15 to 25 percent clay).
Reaction: Strongly alkaline or very strongly alkaline.
Slow or very slow hydraulic conductivity.
Buried Bt horizon
Hue: 7.5YR or 5YR.
Value: 5 or 6 dry, 4 or 5 moist.
Chroma: 4 or 6, dry or moist.
Texture: Loam, sandy clay loam, clay loam (20 to 32 percent clay).
Reaction: Strongly alkaline or very strongly alkaline.
Calcium carbonate equivalent: 5 to 19 percent.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Shontik soils are on stream terraces and fan terraces. Slope ranges from 0 to 3 percent. Elevations range from 1000 to 1450 feet. They formed in Holocene fan or stream alluvium superimposed on Pleistocene relict basin floors. The average annual precipitation is 7 to 10 inches occurring as summer thunderstorms and gentle winter rain. Mean annual temperature is 69 to 75 degrees F. The frost-free period is about 240 to 325 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Casa Grande, Redun, Kamato and Tatai soils. Casa Grande and Kamato soils have natric horizons and Redun lacks a buried paleosol within 40 inches. Tatai soils are loam and silt loam above a buried paleosol.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; slow or very slow permeability.
USE AND VEGETATION: Used for livestock grazing, wildlife habitat and irrigated cropland. Present vegetation is mainly desert saltbush, linear-leaf saltbush and wolfberry.
DISTRIBUTION AND EXTENT: Southern Arizona. MLRA is 40. The soils of this series are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Gila River Indian Reservation, Arizona; Parts of Maricopa and Pinal Counties, 1991. Name means water in the Pima Indian language.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 9 inches (A, Anz).
Cambic horizon - the zone from 9 to 28 inches (Bwnl, Bwn2).
Natric subgroup - SAR exceeds 45 throughout the cambic horizon
Buried soil - the zone from 28 to 60 inches (2Btknzb1, 2Btknzb2, 2Btknzb3).
Slow or very slow hydraulic conductivity in the cambic horizon.
Classified according to Soil Taxonomy Second Edition, 1999
ADDITIONAL DATA: NSSL Sample S84AZ-013-004
NSSL Sample S84AZ-021-016
Gallup BIA Lab Data 278-38-22
Gallup BIA Lab Data 278-89-1
Gallup BIA Lab Data 278-95-2