LOCATION CASA GRANDE AZEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, hyperthermic Typic Natrargids
TYPICAL PEDON: Casa Grande sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.)
An--0 to 1 inch; light yellowish brown (10YR 6/4) fine sandy loam, dark yellowish brown (10YR 4/4) moist; moderate thin platy structure; soft, very friable, nonsticky and nonplastic; many very fine roots; few very fine irregular pores; strongly effervescent; strongly alkaline (pH 8.6); very slightly saline (ECe 2 dS/m) and slightly sodic (SAR 5); clear smooth boundary.
BAn--1 to 5 inches; pale brown (10YR 6/3) fine sandy loam, brown (10YR 4/3) moist; strong medium and coarse angular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine roots; few very fine irregular pores; violently effervescent; strongly alkaline (pH 8.6); very slightly saline (ECe 2 dS/m) and moderately sodic (SAR 28); gradual wavy boundary.
Btknz1--5 to 8 inches; light yellowish brown (10YR 6/4) sandy clay loam, dark yellowish brown (10YR 4/4) moist; moderate medium prismatic structure; hard, very friable, sticky and plastic; few very fine roots; common very fine tubular and irregular pores; common distinct clay skins on ped faces and lining pores; few fine and medium, rounded, soft accumulations of lime and salt (6 percent CaCO3); violently effervescent; very strongly alkaline (pH 9.6); slightly saline (ECe 6 dS/m) and strongly sodic (SAR 65); clear smooth boundary.
Btknz2--8 to 11 inches; light yellowish brown (10YR 6/4) sandy clay loam, dark yellowish brown (10YR 4/4) moist; moderate medium prismatic structure; hard, very friable; sticky and plastic; few very fine roots; common very fine tubular and irregular pores; common distinct clay skins on ped faces and lining pores; few fine and medium, rounded, soft accumulations of lime and salt (10 percent CaCO3); violently effervescent; very strongly alkaline (pH 9.6); moderately saline (ECe 8 dS/m) and strongly sodic (SAR 107); gradual wavy boundary.
Btknz3--11 to 18 inches; strong brown (7.5YR 5/6) clay loam, strong brown (7.5YR 4/6) moist; strong medium prismatic structure parting to strong medium and coarse angular blocky; hard, very friable, sticky and plastic; few very fine and fine roots; common very fine and fine and few fine tubular and irregular pores; many prominent clay skins on ped faces and lining pores; many medium and coarse, vertically oriented, cylindrical, soft accumulations of lime (14 percent CaCO3); violently effervescent; strongly alkaline (pH 8.8); strongly saline (ECe 16 dS/m) and strongly sodic (SAR 185); gradual wavy boundary.
Btknz4--18 to 32 inches; strong brown (7.5YR 5/6) clay loam, strong brown (7.5YR 4/6) moist; strong medium prismatic structure parting to strong medium and coarse angular blocky; hard, very friable, sticky and plastic; few very fine and fine roots; common very fine and few fine tubular and irregular pores; many prominent clay skins on ped faces and lining pores; few dark brown manganese coatings on ped faces; many medium and coarse, vertically oriented, cylindrical, soft accumulations of lime (19 percent CaCO3); violently effervescent; strongly alkaline (pH 8.8); strongly saline (ECe 27 dS/m) and strongly sodic (SAR 147); clear wavy boundary.
Btknz5--32 to 39 inches; brown (7.5YR 5/4) clay loam, brown (7.5YR 4/4), moist; moderate medium and coarse angular blocky structure; very hard, very friable, sticky and plastic; few very fine irregular pores; few fine clay skins bridging mineral grains; few dark brown manganese coatings on ped faces; few fine and medium, rounded, soft accumulations of lime (15 percent CaCO3); violently effervescent; strongly alkaline (pH 8.8); strongly saline (ECe 26 dS/m) and strongly sodic (SAR 137); abrupt smooth boundary.
2BCknz1--39 to 46 inches; light yellowish brown (10YR 6/4) sandy clay loam, dark yellowish brown (10YR 4/4) moist; moderate medium subangular blocky structure; hard, firm, sticky and plastic; few fine irregular pores; 14 percent fine and medium gravel; few dark brown manganese coatings on ped faces; many soft lime coatings on gravel (8 percent CaCO3); violently effervescent; strongly alkaline (pH 8.8); strongly saline (ECe 25 dS/m) and strongly sodic (SAR 77); clear smooth boundary.
2BCknz2--46 to 60 inches; light brown (7.5YR 6/4) sandy clay loam, brown (7.5YR 5/4) moist; weak medium subangular blocky structure; hard, firm, sticky and plastic; few very fine irregular pores; many coarse and very coarse, soft, rounded accumulations of lime (17 percent CaCO3); dominantly violently effervescent with spots that are noneffervescent; moderately alkaline (pH 8.4); strongly saline (ECe 29 dS/m) and strongly sodic (SAR 29).
TYPE LOCATION: Maricopa County, Arizona; on the Gila River Indian Reservation, about 2450 feet south and 2500 feet east of the NW corner of sec. 29, T.2 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 78 degrees F.
Rock fragments - Less than 15 percent; some pedons contain hardpan fragments as a part of the coarse fraction.
Salinity - Slightly to strongly saline
Sodicity - Slightly to strongly sodic
Depth to calcic horizon - 20 to 40 inches. Occurs mostly as vertically oriented, cylindrical masses.
Organic matter content - Less than one percent
Reaction - Moderately alkaline to very strongly alkaline
A horizon
Hue: 10YR, 7.5YR
Value: 5, 6, or 7 dry, 3 through 6 moist
Chroma: 3, 4, or 6, dry or moist
Btn horizon
Hue: 7.5YR, 5YR, 10YR
Value: 3 through 7 dry, 3, 4, or 5 moist
Chroma: 3, 4, 5, 6, or 8, dry or moist
Texture: Loam, sandy clay loam, clay loam (18 to 35 percent clay)
B, BC or C horizon
Hue: 10YR, 7.5YR, 5YR
Value: 5, 6, or 8 dry, 4, 5, or 6 moist
Chroma: 2, 3, 4, 6 or 8, dry or moist
Texture: Sandy clay loam, loam, sandy loam, clay loam, silt loam, silty clay loam; some pedons have strata of coarser textures at 40 to 60 inches. (10 to 25 percent clay)
In some pedons an E horizon occurs below the A horizon and above the Bt horizon. Where present it is from 1 to 3 inches thick.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Casa Grande soils are on nearly level fan terraces and relict basin floors at elevations of 700 to 2,000 feet. Slopes range from 0 to 5 percent. These soils formed in old alluvium from a wide variety of rocks including granite, rhyolite, andesite, quartzite and possibly some limestone and basalt. Annual precipitation is 6 to 10 inches; and the mean annual air temperature is 67 to 75 degrees F. The frost-free period ranges from 240 to 350 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kamato, Redun, Shontik and Tatai soils. Kamato soils average more than 35 percent clay in the control section. Redun, Shontik and Tatai soils do not have argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; slow or very slow permeability.
USE AND VEGETATION: Used for livestock grazing, wildlife habitat and irrigated cropland. Vegetation is desert saltbush, linear-leaf saltbush, wolfberry and scattered mesquite.
DISTRIBUTION AND EXTENT: Southern Arizona; mainly in the central valley areas. This series is moderately extensive. MLRA is 40.
MLRA OFFICE RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Pinal County (Casa Grande Area), Arizona; 1936.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 1 inch (A horizon)
Natric horizon - The zone from 1 to 23 inches (Btn, Btknz, Btknzy horizons)
Calcic horizon - The zone from 23 to 60 inches (Bkn1, 2Bkn2 horizons)
Keys to Soil Taxonomy - Series classified according to Eighth Edition, 1998.
The type location was changed in November 1999 to the site of the proposed state soil.