LOCATION BOSA AZEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Lithic Haplargids
TYPICAL PEDON: Bosa gravelly fine sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 1 inch; brown (7.5YR 5/4) gravelly fine sandy loam, brown (7.5YR 4/4) moist; weak thin platy structure; soft, very friable, sticky and nonplastic; common very fine and fine roots; common very fine and fine interstitial pores; 20 percent gravel; noneffervescent; slightly alkaline (pH 7.6); abrupt smooth boundary. (1 to 3 inches thick)
Bt--1 to 6 inches; reddish brown (5YR 5/4) very gravelly loam, reddish brown (5YR 4/4) moist; moderate fine subangular blocky structure; soft, friable, sticky and plastic; common fine and medium roots; common very fine and fine interstitial and tubular pores; many distinct continuous clay films on faces of peds and on rock fragments; 5 percent cobble and 50 percent gravel; noneffervescent; slightly alkaline (pH 7.6); clear wavy boundary. (4 to 16 inches thick)
Crt--6 to 8 inches; weathered andesite; common distinct reddish brown (5YR 5/4) continuous clay films on rock fragments; abrupt wavy boundary. (0 to 3 inches thick)
R--8 inches; andesite.
TYPE LOCATION: Pima County, Arizona; latitude 31 degrees 57 minutes 15 seconds North and a longitude of 112 degrees 58 minutes 00 seconds West. Located about 4 miles west of Sells in the mountains referred to as "The Birdnest".
RANGE IN CHARACTERISTICS:
Soil moisture: Intermittently moist in some part of the soil moisture control section for more than 20 days cumulative during July - September and also intermittently moist during December - February. Driest during May and June. Typic aridic soil moisture regime.
Soil temperature: 69 to 72 degrees F.
Rock fragments: 35 to 75 percent gravel, cobble and/or stones
Clay Content: ranges from 15 to 35 percent; averages more than 18 percent in the control section
Reaction: mildly to moderately alkaline
Depth to bedrock: 6 to 20 inches
Organic matter: less than 1 percent
A horizon
Value: 4 through 6 dry
Chroma: 3 or 4, dry or moist
Bt horizon
Hue: 5YR, 7.5YR
Value: 4 through 6 dry, 3 through 5 moist
Chroma: 4 through 6 dry, 3 or 4 moist
Texture: loam, clay loam, sandy clay loam
Calcium carbonate: noneffervescent to strongly effervescent; 0 to 10 percent calcium carbonate equivalent
Some pedons do not have layers of highly fractured andesite above the lithic contact. Clay films and calcium carbonate coatings are common in the fractures. This layer is less than 3 inches thick.
COMPETING SERIES: These are the Artillery (CA), Newera (NV), Pasopeak (CA) and Zibate (NV) series. Artillery, Newera, Pasopeak, and Zibate soils are in the Mohave Desert (MLRA 30) and receive most of the precipitation in the winter.
GEOGRAPHIC SETTING: Bosa soils are on hills and mountains. Slopes range from 15 to 35 percent. They formed in residuum, colluvium, and mixed slope alluvium from igneous rock mainly andesite, porphyritic tuff, and rhyolite. Elevation ranges from 2,000 to 3,500 feet. The mean annual precipitation is 10 to 13 inches. The mean annual air temperature ranges from 67 to 70 degrees F. The frost-free period is about 240 to 260 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lajitas and Gunsight soils. Lajitas soils do not have argillic horizons. Gunsight soils are very deep.
DRAINAGE AND PERMEABILITY: Well drained; rapid runoff; moderate permeability.
USE AND VEGETATION: Bosa soils are used for livestock grazing and wildlife habitat. Vegetation includes sideoats grama, slender grama, slender janusia, twinberry, Indian mallow, club moss, jojoba, Mormon tea, littleleaf paloverde, wolfberry and ocotillo.
DISTRIBUTION AND EXTENT: Southern Arizona. This series is of moderate extent. MLRA is 40.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Pima County, Arizona; Soil survey of Tohono O'odham Indian Reservation, AZ, Parts of Maricopa, Pima and Pinal Counties; 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 1 inches (A horizon)
Argillic horizon - The zone from 1 to 6 inches (Bt horizon)
Lithic contact - The boundary at 8 inches (R Horizon)