LOCATION GADSDEN AZEstablished Series
TAXONOMIC CLASS: Fine, smectitic, calcareous, hyperthermic Vertic Torrifluvents
TYPICAL PEDON: Gadsden clay - cultivated. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 10 inches; brown (7.5YR 5/2) clay, dark brown (7.5YR 3/2) moist; weak fine subangular blocky structure; very hard, friable, moderately sticky and moderately plastic; common medium roots; common fine tubular pores; strongly effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (8 to 14 inches thick)
A--10 to 29 inches; brown (10YR 4/3) stratified clay, dark brown (7.5YR 3/2) moist; massive; very hard, friable, moderately sticky and moderately plastic; common fine roots; few very fine tubular pores; few pressure faces; strongly effervescent; few fine filaments of calcium carbonate in the lower part; moderately alkaline (pH 8.0); clear smooth boundary. (8 to 24 inches thick)
C1--29 to 43 inches; brown (7.5YR 5/4) weakly stratified clay, dark brown (7.5YR 3/2) moist; massive; very hard, friable, moderately sticky and very plastic; common fine roots; common fine tubular pores; strongly effervescent; few fine filaments of calcium carbonate; moderately alkaline (pH 8.0); abrupt smooth boundary. (8 to 22 inches thick)
C2--43 to 60 inches; brown (7.5YR 5/4) weakly stratified clay loam, brown (7.5YR 4/4) moist; massive; hard, friable, slightly sticky and moderately plastic; common very fine roots; few fine tubular pores; common black (10YR 2/1) stains; slightly effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Maricopa County, Arizona; 78 feet west and 294 feet north of the southeast corner of section 16, T. 1 N., R. 2 E. Latitude of 33 degrees, 25 minutes, 24 seconds N., Longitude of 112 degrees, 9 minutes, 7 seconds W., NAD 83.
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 76 degrees F.
Soil cracking - When dry, cracks 1 cm or more wide, extend to depths of 50 cm or more. Pressure faces created by desiccation cracking are common at depths of 10 to 20 inches.
Rock fragments - Averages less than 35 percent in the control section
Reaction - Neutral to very strongly alkaline
Clay content - Averages 35 to 60 percent in the control section
Salinity- Nonsaline to strongly saline
Sodicity- nonsodic to moderately sodic
Calcium Carbonate Equivalent - Less than 10 percent
Organic matter content - Less than 1 percent. Decreases irregularly with depth.
Consistence: Very hard or hard, dry and firm or friable, moist
C horizon
Hue: 5YR, 7.5YR, 10YR
Value: 4, 5, 6, or 7 dry, 3, 4, or 5 moist
Chroma: 2, 3, or 4, dry or moist
Texture: Clay, silty clay, clay loam, silty clay loam; some pedons have strata (less than 2 inches) of coarser textures.
COMPETING SERIES: This is the Imperial (CA) series. Imperial soils contain gypsum, and have very hard or extremely hard consistence when dry and very firm or extremely firm consistence when moist. In addition, Imperial soils are moist in some part of the soil moisture control section for less than 20 days cumulative between July and September.
GEOGRAPHIC SETTING: Gadsden soils are on flood plains at elevations of 75 to 2100 feet. Slopes are less than 3 percent. These soils formed in stratified stream alluvium from quartzite, schist, and granite-gneiss. Gadsden soils are in a hot arid continental climate. The mean annual precipitation ranges from 2 to 10 inches occurring as summer thunderstorms and gentle winter rains. Mean annual air temperature ranges from 70 to 76 degrees F. The frost-free period is about 240 to 325 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Antho, Avondale, Cashion, Gilman, Glenbar, and Vint soils. Antho and Gilman soils are coarse-loamy. Avondale soils are fine-loamy. Vint soils are sandy.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; slow permeability.
USE AND VEGETATION: These soils are used for irrigated crops and for livestock grazing. Irrigated crops are cotton, alfalfa, sorghums, sugar beets, small grains and truck crops. Vegetation is creosotebush, desert saltbush, salt cedar, inkweed, and annual weeds and grasses.
DISTRIBUTION AND EXTENT: Southern Arizona and southeastern California. These soils are moderately extensive. MLRAs are 31 & 40.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Central Maricopa County Area, Arizona; 1972.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Entisol feature - the absence of diagnostic subsurface horizons
Vertic subgroup - deep wide cracks and potential linear extensibility greater than 6 cm.
Fine stratification in the lower part.
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Tenth Edition, 2006.
Revised for the completion of AZ661, 1/2009, WWJ