LOCATION SAHUARITA AZEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, thermic Typic Haplocambids
TYPICAL PEDON: Sahuarita very gravelly fine sandy loam-rangeland (Colors are for dry soil unless otherwise noted).
A--0 to 3 inches; light yellowish brown (10YR 6/4) very gravelly fine sandy loam, dark yellowish brown (10YR 4/4) moist; weak moderately thick platy structure; soft, very friable, nonsticky and nonplastic; few fine roots; common very fine tubular pores; 45 percent gravel; strongly effervescent; moderately alkaline (pH 7.9); abrupt wavy boundary (1 to 10 inches thick).
Bk--3 to 19 inches; light yellowish brown (10YR 6/4) fine sandy loam, brown (10YR 4/3) moist; weak coarse prismatic structure; soft, very friable, slightly sticky and nonplastic; common fine roots; common fine tubular pores; 10 percent gravel; strongly effervescent as few faint calcium carbonate coatings on undersides of gravel; moderately alkaline (pH 7.9); gradual smooth boundary (10 to 30 inches thick).
C--19 to 28 inches; light yellowish brown (10YR 6/4) fine sandy loam, dark yellowish brown (10YR 4/4) moist; massive; soft, very friable, slightly sticky and nonplastic; common fine roots; few fine tubular pores; 10 percent gravel; strongly effervescent; moderately alkaline (pH 7.9); clear wavy boundary (9 to 15 inches thick).
2Btkb--28 to 45 inches; brown (7.5YR 5/4) loam, brown (7.5YR 4/4) moist; weak medium prismatic structure; hard, firm, sticky and plastic; common fine roots; common fine and very fine tubular pores; common faint clay films coating sand grains and lining pores; 10 percent gravel; strongly effervescent as few faint calcium carbonate filaments on faces of peds; moderately alkaline (pH 8.0); clear wavy boundary (10 to 25 inches thick).
2Btb--45 to 60 inches; brown (7.5YR 5/4) very gravelly sandy clay loam, brown (7.5YR 4/4) moist; weak medium prismatic structure; hard, friable, slightly sticky and slightly plastic; few fine roots; few fine tubular pores; many faint clay films coating sand grains and lining pores; 35 percent gravel; strongly effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Pima County, Arizona; 460 feet north and 1060 feet west of the southeast corner of section 7, T. 17 S., R. 15 E.
RANGE IN CHARACTERISTICS:
Soil moisture - Intermittently moist in some part of the soil moisture control section part during July-September and December-March. Driest during May and June. Typic aridic soil moisture regime.
Soil temperature - 66 to 72 degrees F.
The control section averages less than 18 percent clay
Depth to buried argillic horizon - 20 to 40 inches
Rock fragments - 0 to 65 percent in any one horizon; averages less than 35 percent in the particle-size control section
Calcium carbonate - Slightly to strongly effervescent and less than 15 percent calcium carbonate equivalent at depths less than 40 inches; violently effervescent and as much as 25 percent calcium carbonate equivalent at depths of more than 40 inches
A horizon
Hue: 10YR, 7.5YR, 5YR
Value: 4 through 6 dry, 4 or 5 moist
Chroma: 3, 4, or 6, dry or moist
Organic matter: less than 1 percent
Reaction: mildly or moderately alkaline
Bk or Bw and C horizons
Hue: 10YR, 7.5YR, 5YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3, 4, or 6, dry or moist
Texture: loam, very fine sandy loam, fine sandy loam, sandy loam (10 to 17 percent clay)
Reaction: slightly alkaline or moderately alkaline
Buried Bt horizon
Hue: 7.5YR, 5YR
Value: 4, 5, or 6 dry, 4 or 5 moist
Chroma: 3 through 6, dry or moist
Texture: loam, sandy loam, coarse sandy loam, sandy clay loam, clay loam (averages 18 to 35 percent clay)
Reaction: slightly to strongly alkaline
COMPETING SERIES: These are the Agustin (AZ), Filaree (AZ), Hayhook (AZ), Lostman (AZ), Nasagold (CA), Pajarito (TX), and Pyxo (CA) series. All of these soils lack buried argillic horizons. In addition, Filaree, Lostman, and Nasagold soils are in the Mohave Desert (MLRA 30); Pyxo soils are in the Central California Coast Range. All these soils are dry in some part of the soil moisture control section for more than 20 days cumulative between July and September. Hayhook soils are noncalcareous to depths of 20 inches or more. Pyxo soils are moderately deep to sandstone bedrock. Pajarito soils contain less than 15 percent rock fragments in the control section.
GEOGRAPHIC SETTING: Sahuarita soils are on fan terraces and basin floors with slopes of 0 to 8 percent. They formed in stratified alluvium from limestone, schist, phyllite, and granitic rock. Elevation ranges from 2000 to 3600 feet. Mean annual precipitation is 10 to 13 inches occurring as summer thunderstorms and winter rain. Mean annual air temperature is 64 to 70 degrees F. The frost-free period is about 230 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arizo, Bucklebar, Mohave, Stagecoach, and Pinaleno series. Arizo soils are sandy-skeletal and are in drainageways. Bucklebar and Mohave soils have argillic horizons. Stagecoach and Pinaleno soils are loamy-skeletal.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderate or moderately rapid permeability above the buried argillic horizons and moderately slow or moderate within.
USE AND VEGETATION: Used mainly for livestock grazing and some homesites. Vegetation is creosotebush, bush muhly, threeawn, fluffgrass, whitestem paperflower, desert zinnia, and annual forbs and grasses.
DISTRIBUTION AND EXTENT: Southern Arizona. These soils are moderately extensive (MLRA 40).
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Pima County, Arizona, Eastern Part; 1986.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 3 inches (A horizon)
Cambic horizon - the zone from 3 to 19 inches (Bk horizon)
Buried soil - the zone from 28 to 60 inches (2Btkb, 2Btb horizons)
Classified according to Soil Taxonomy, Second Edition, 1999
Updated competing series section 3/13/08, CEM