LOCATION YAQUI AZEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Fluventic Haplocambids
TYPICAL PEDON: Yaqui fine sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 4 inches; strong brown (7.5YR 5/6) fine sandy loam, strong brown (7.5YR 4/6) moist; weak moderately thick platy structure parting to weak fine subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; many vesicular pores; 5 percent gravel; slightly effervescent; moderately alkaline (pH 7.9); gradual wavy boundary. (1 to 5 inches thick)
Bw1--4 to 18 inches; brown (7.5YR 5/4) sandy clay loam, brown (7.5YR 4/4) moist; weak medium prismatic structure parting to moderate fine subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many fine and very fine and few medium roots; common fine and very fine tubular pores; common fine calcium carbonate filaments and few thin coatings on undersides of gravel; 5 percent gravel; strongly effervescent; moderately alkaline (pH 8.0); gradual smooth boundary.
Bw2--18 to 31 inches; brown (7.5YR 4/4) sandy clay loam, dark brown (7.5YR 3/4) moist; moderate medium prismatic structure parting to weak fine and medium subangular blocky; common fine and very fine roots; many very fine tubular pores; patchy faint organic coatings on faces of peds; common fine calcium carbonate filaments and few thin coatings on gravel; 5 percent gravel; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (Combined thickness of the Bw horizon(s) is 19 to 35 inches)
2Btb--31 to 43 inches; yellowish red (5YR 5/6) clay loam, yellowish red (5YR 4/6) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, friable, very sticky and very plastic; common fine and very fine roots; common fine and few medium tubular pores; patchy faint clay films coating sand grains and lining pores; few thin calcium carbonate coatings on gravel; 10 percent gravel; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (10 to 30 inches thick)
2Bkb--43 to 60 inches; pink (7.5YR 7/4) gravelly loam, brown (7.5YR 5/4) moist; massive; slightly hard, very friable, sticky and slightly plastic; common very fine roots; many medium soft calcium carbonate masses; 25 percent gravel; violently effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Pima County, Arizona; 2600 feet east and 10 feet north of the southwest corner of section 15, T. 17 S., R. 14 E.
RANGE IN CHARACTERISTICS:
Soil moisture - Intermittently moist in some part of the soil moisture control section during July-September and December-March. Driest during May and June. Typic aridic soil moisture regime.
Soil temperature - 66 to 69 degrees F.
Clay content - 18 to 27 percent
Organic matter - Decreases irregularly with depth, averages less than 1 percent in the upper 15 inches
Rock fragments - less than 15 percent
Depth to buried soil - 20 to 40 inches
A horizon
Hue: 10YR, 7.5YR
Value: 4, 5, or 6 dry, 4 or 5 moist
Chroma: 3, 4 or 6, dry or moist
Reaction: Slightly alkaline or moderately alkaline
Bw horizon(s)
Hue: 10YR, 7.5YR
Value: 4, 5, or 6 dry, 4 or 5 moist
Chroma: 3, 4, or 6, dry or moist
Texture: Loam, sandy clay loam, fine sandy loam, sandy loam (averages 15 to 25 percent clay)
Reaction: Slightly alkaline or moderately alkaline
Btb horizon(s)
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, sandy clay loam, clay loam (averages 20 to 35 percent clay)
Reaction: Moderately alkaline or strongly alkaline
Bkb horizon (where present)
Hue: 10YR, 7.5YR
Value: 6 or 7 dry, 5 or 6 moist
Chroma: 2, 3, or 4 dry, 3 or 4 moist
Texture: Loam, sandy loam
Reaction: Moderately alkaline or strongly alkaline
COMPETING SERIES: This is the Cerini (CA) series. Cerini soils are in the San Joaquin Valley of California (MLRA 17) receive mostly winter precipitation and are usually dry from April through November.
GEOGRAPHIC SETTING: Yaqui soils are on alluvial fans with slopes of 0 to 3 percent. They formed in stratified fan alluvium from limestone, schist, phyllite, sandstone and granitic rock. Elevation ranges from 2200 to 3600 feet. Mean annual precipitation is 10 to 12 inches. 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 and Tubac series. Arizo soils are sandy-skeletal. Bucklebar, Mohave and Tubac soils have argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate permeability in the A and Bw horizons and moderately slow in the buried argillic horizon.
USE AND VEGETATION: Used mainly for livestock grazing and some homesites. Vegetation is creosotebush, mesquite, spiny haplopappus, bush muhly, threeawn, pappusgrass, annual forbs and grasses.
DISTRIBUTION AND EXTENT: Southern Arizona. These soils are not extensive. MLRA 40 & 41.
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 4 inches (A horizon)
Cambic horizon - the zone from 4 to 31 inches (Bw1, Bw2 horizons)
Buried soil - the zone from 31 to 60 inches (2Btb, 2Bkb horizons)
Classified according to Soil Taxonomy Second Edition, 1999; Keys to Soil Taxonomy Tenth Edition, 2006.