LOCATION KEYSTO AZEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, nonacid, thermic Ustic Torrifluvents
TYPICAL PEDON: Keysto very gravelly sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.)
C1--0 to 3 inches; dark brown (7.5YR 3/2) very gravelly sandy loam, dark brown (7.5YR 3/2) moist; weak thin platy structure; soft, very friable, nonsticky and nonplastic; common very fine, fine and medium roots; common fine irregular pores; 5 percent cobble and 45 percent gravel; noneffervescent; neutral (pH 6.6); abrupt smooth boundary. (2 to 5 inches thick)
C2--3 to 24 inches; dark brown (10YR 3/3) extremely cobbly sandy loam, very dark brown (10YR 2/2) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine, fine, medium and coarse roots; common fine irregular pores; 55 percent cobble and 24 percent gravel; noneffervescent; neutral (pH 6.8); clear wavy boundary. (20 to 30 inches thick)
Ck--24 to 60 inches; brown (10YR 4/3) extremely cobbly loamy sand, dark brown (10YR 3/3) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine, fine, and few medium roots; common fine irregular pores; many distinct continuous calcium carbonate coatings on rock fragments; 55 percent cobble and 30 percent gravel; noneffervescent in the fine earth; slightly alkaline (pH 7.4).
TYPE LOCATION: Pima County, Arizona; latitude of 31 degrees 47 minutes 33 seconds North and a longitude of 111 degrees 39 minutes 30 seconds West. Chiuli Shaik topoquad, Sycamore Canyon road.
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. The epipedon is moist in some part less than 90 days (cumulative) when the soil temperature is above 41 degrees F. in 7 out of 10 years. Ustic Aridic soil moisture regime.
Soil temperature: 61 to 69 degrees F.
Rock fragments: 35 to 75 percent gravel, cobble, and stones
Reaction: slightly acid to slightly alkaline
Organic matter: 1 to 3 percent, decreasing irregularly with depth
Depth to calcium carbonate: greater than 20 inches
C horizons
Hue: 10YR, 7.5YR
Value: 3 through 5 dry, 2 through 4 moist
Chroma: 2 through 4, dry or moist
Texture: sandy loam, loamy sand, fine sandy loam, coarse sand
Calcium carbonate: occurs as coatings on rock fragments
COMPETING SERIES: There are no competitors.
GEOGRAPHIC SETTING: The Keysto soils are on alluvial fans and stream terraces. Slope ranges from 0 to 8 percent. They formed in mixed fan and stream alluvium. Elevation ranges from 3,000 to 5,200 feet. The mean annual precipitation is 12 to 16 inches. The mean annual air temperature ranges from 59 to 67 degrees F. The frost-free period is about 180 to 250 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lampshire, Romero, Chiricahua, and Oracle soils. These soils have bedrock within 60 inches.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderately rapid permeability.
USE AND VEGETATION: Keysto soils are used for livestock grazing and wildlife habitat. Vegetation includes mesquite, paloverde, catclaw acacia, burroweed, cacti, sideoats grama, Arizona cottontop, spike dropseed, annual grasses and forbs.
DISTRIBUTION AND EXTENT: Southern Arizona. This series is of moderate extent. This soil occurs in LRR-D, MLRAs 40 and 41. Subject to flooding.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Pima County, Arizona; Soil survey of Tohono O'odham Nation, AZ, Parts of Maricopa, Pima and Pinal Counties; 1993.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Entisol feature - The absence of diagnostic subsurface horizons
Fluvial feature - Irregular decrease in organic carbon in the zone from 3 to 60 inches (C2, Ck horizons)
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Tenth Edition, 2006.