LOCATION MULE AZEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, carbonatic, thermic Ustic Haplocalcids
TYPICAL PEDON: Mule very gravelly fine sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 2 inches; brown (7.5YR 5/3) very gravelly fine sandy loam, brown (7.5YR 4/3) moist; weak thin platy structure parting to weak fine granular; soft, very friable, nonsticky and nonplastic; few fine roots; few fine irregular and tubular pores; 50 percent gravel; violently effervescent, 40 percent calcium carbonate equivalent; moderately alkaline (pH 8.2); abrupt smooth boundary. (2 to 6 inches thick)
Bk1--2 to 10 inches; brown (7.5YR 5/3) very gravelly fine sandy loam, brown (7.5YR 4/3) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; few fine tubular pores; many distinct calcium carbonate coatings on rock fragments; 5 percent cobble and 50 percent gravel; violently effervescent, 49 percent calcium carbonate equivalent; moderately alkaline (pH 8.4); clear wavy boundary.
Bk2--10 to 22 inches; light brown (7.5YR 6/3) and pinkish white (7.5YR 8/2) very gravelly loam, brown (7.5YR 5/3) and pinkish gray (7.5YR 7/2) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; few fine tubular pores; many distinct calcium carbonate coatings on rock fragments; 5 percent cobble and 43 percent gravel; violently effervescent, 67 percent calcium carbonate equivalent; moderately alkaline (pH 8.4); clear wavy boundary.
Bk3--22 to 60 inches; pinkish white (7.5YR 8/2) and light brown (7.5YR 6/3) very gravelly loam, pinkish gray (7.5YR 7/2) and brown (7.5YR 5/3) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; few fine irregular and tubular pores; many distinct calcium carbonate coatings on rock fragments; 46 percent gravel; violently effervescent, 47 percent calcium carbonate equivalent; moderately alkaline (pH 8.4). (Combined thickness of the Bk horizons is 35 to 58 inches)
TYPE LOCATION: Walnut Gulch Experimental Watershed, Cochise County, Arizona; located at a latitude of 31 degrees, 41 minutes, 55 seconds North and longitude of 110 degrees, 01 minutes, 40 seconds West; 650 feet west and 790 feet south from the northeast corner of section 18, T. 20 S., R. 23 E.
RANGE IN CHARACTERISTICS:
Soil moisture - Intermittently moist in some part of the soil moisture control section during July - September and December - February. Moist in the epipedon for less than 3 months cumulative per year. Driest during May and June. Ustic aridic soil moisture regime.
Soil Temperature: 62 to 69 degrees F.
Rock fragments: About 45 to 55 percent gravel on the surface. Rock fragments average more than 35 percent in the particle-size control section
Reaction: slightly or moderately alkaline
Depth to calcic horizon: 2 to 10 inches
Clay content: 5 to 18 percent
Organic Matter: 1 to 3 percent
A horizon
Hue: 7.5YR, 10YR
Value: 4 to 6, dry, 3 to 5 moist
Chroma: 2 to 4, dry or moist
Effervescence: strong or violent, 30 to 45 percent calcium carbonate equivalent
Bk horizon
Hue: 7.5YR, 10YR
Value: 5 through 8 dry, 4 through 7 moist
Chroma: 2 to 3, dry or moist
Texture: loam, fine sandy loam, sandy loam
Effervescence: strong or violent, 40 to 70 percent calcium carbonate equivalent
COMPETING SERIES: These are the Bankston (NM), Bascal (NM), Bascom (NM), Cienega (TX), and Crotalus (NM) series. Bankston soils are moderately deep. Bascom soils are in the Great Plains and are moist in the soil moisture control section during May and June. Bascal soils contain 18 to 35 percent clay in the control section. Cienega soils have total clay content that ranges from 20 to 35 percent. Crotalus soils contain 25 to 35 percent clay in the control section
GEOGRAPHIC SETTING: Mule soils are on fan terraces at elevations of 3,800 to 4,800 feet. Slopes range from 3 to 45 percent. These soils formed in mixed calcareous fan alluvium. The mean annual precipitation is 12 to 16 inches and occurs as thunderstorms during July to September and as gentle rains during December and January. The mean annual air temperature is 60 to 67 degrees F. The frost-free period is 180 to 250 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Sutherland and Mabray soils. Sutherland and Mabray soils are very shallow or shallow.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability.
USE AND VEGETATION: Used for experimental rangeland research, livestock grazing and wildlife habitat. Vegetation includes whitethorn, desert zinnia, mariola, tarbush, sandpaper plant, creosotebush, black grama, bush muhly, slim tridens, desert needlegrass and sideoats grama.
DISTRIBUTION AND EXTENT: Southern Arizona. Mule soils are of moderate extent. MLRA is 41. Named derived from the nearby Mule Mountains.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Cochise County, Arizona; Soil survey of Cochise County, Arizona, Douglas-Tombstone Part; 1996.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 2 inches(A horizon)
Calcic horizon - The zone from 2 to 60 inches (Bk1, Bk2, Bk3 horizons)
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Tenth Edition, 2006.