LOCATION CORTARO AZEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, nonacid, mesic Lithic Ustorthents
TYPICAL PEDON: Cortaro extremely gravelly sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 3 inches; brown (10YR 5/3) extremely gravelly sandy loam, dark brown (10YR 3/3) moist; weak medium granular structure; slightly hard, friable, nonsticky and nonplastic; common fine roots; common fine tubular pores; 60 percent gravel and 10 percent flagstones and channers; neutral; clear smooth boundary. (1 to 5 inches thick)
C--3 to 12 inches; pale brown (10YR 6/3) very gravelly sandy loam, brown (10YR 4/3) moist; massive; slightly hard, friable, nonsticky and nonplastic; common fine roots; common fine tubular pores; 45 percent gravel; slightly acid; abrupt wavy boundary. (4 to 15 inches thick)
R--12 inches; gneiss; few coarse roots in fractures.
TYPE LOCATION: Pima County, Arizona: Located about 150 feet south and 600 feet east of the northwest corner of section 31, T.14.S., R.17.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. Aridic ustic soil moisture regime.
Soil temperature: 57 to 59 degrees F.
Depth to bedrock: 12 to 20 inches
Reaction: moderately acid to neutral
Organic matter: less than 1 percent
Rock fragments: 35 to 70 percent gravel, channers and flagstones
A and C horizons
Hue: 10YR, 7.5YR
Value: 5 through 7 dry
Chroma: 2 through 6
COMPETING SERIES: These are the Chimayo (NM), Hailstone (AZ) and Telephone (AZ) series. Chimayo soils have a mean annual soil temperature of 50 to 54 degrees F. and are dry in the soil moisture control section for longer periods due to a lower rainfall component. Hailstone soils have a lower soil temperature and a higher rainfall component and they formed in residuum and colluvium from rhyolitic tuff. Telephone soils have a mean annual soil temperature of 47 to 56 degrees F.
GEOGRAPHIC SETTING: The Cortaro soils are on hills and mountains. Slopes range from 15 to 45 percent. They formed in alluvium and colluvium derived dominantly from granite, gneiss and schist. Elevation ranges from 5,400 to 6,200 feet. The mean annual precipitation is 16 to 20 inches. The mean annual air temperature is about 55 to 57 degrees F. The frost-free period is 160 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Faraway series. Faraway soils have a mollic epipedon.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderately rapid permeability.
USE AND VEGETATION: Cortaro soils are used for livestock grazing, recreation and wildlife habitat. Vegetation includes Emory oak and Arizona white oak, bullgrass, prairie junegrass, sideoats grama, plains lovegrass, cane bluestem, Texas bluestem, catclaw mimosa, other perennial grasses and forbs.
DISTRIBUTION AND EXTENT: Southern Arizona. This series is of moderate extent. MLRA is 41.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Pima County, Arizona; Soil survey of Pima County, Arizona, Eastern Part; 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 3 inches (A horizon)
Entisol feature - The absence of diagnostic subsurface horizons
Lithic contact - The boundary at 12 inches (R horizon)