LOCATION GRAVEYARD AZEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Petronodic Haplocalcids
TYPICAL PEDON: Graveyard fine sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 3 inches; strong brown (7.5YR 4/6) fine sandy loam, dark brown (7.5YR 3/4) moist; weak thin platy structure; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; common fine irregular pores; 5 percent gravel; slightly effervescent; slightly alkaline (pH 7.8); clear smooth boundary. (1 to 5 inches thick)
Bk--3 to 9 inches; brown (7.5YR 5/4) sandy loam, brown (7.5YR 4/4) moist; weak very fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; few fine irregular pores; common distinct calcium carbonate coatings on rock fragments; 10 percent gravel; strongly effervescent, 19 percent calcium carbonate equivalent; moderately alkaline (pH 8.0); clear wavy boundary.
Bkc--9 to 16 inches; brown (7.5YR 5/4) very gravelly sandy loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common very fine and fine roots; few fine irregular pores; common distinct organic coatings on ped faces and in pores; 45 percent petronodes; violently effervescent, 40 percent calcium carbonate equivalent; moderately alkaline (pH 8.4); abrupt wavy boundary.
Bky--16 to 34 inches; 60 percent brown (7.5YR 5/4) and 40 percent light brown (7.5YR 6/4) extremely gravelly sandy loam, 60 percent brown (7.5YR 4/4) and 40 percent brown (7.5YR 5/4) moist; massive; hard, firm, slightly sticky and moderately plastic; common very fine and fine roots; few fine irregular pores; many distinct calcium carbonate coatings on the rock fragments; few gypsum crystals; 70 percent gravel; violently effervescent, 30 percent calcium carbonate equivalent; moderately alkaline (pH 8.0); abrupt wavy boundary.
Bkyc'--34 to 56 inches; 70 percent brown (7.5YR 5/4) and 30 percent light brown (7.5YR 6/4) very gravelly sandy loam, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure; hard, very firm, slightly sticky and moderately plastic; common very fine and fine roots; common fine tubular pores; many distinct calcium carbonate coatings on ped faces; common fine and medium soft calcium carbonate masses; 45 percent petronodes; few fine gypsum crystals; 5 percent gravel; violently effervescent, 15 percent calcium carbonate equivalent; slightly alkaline (pH 7.8); abrupt smooth boundary.
Bky'--56 to 60 inches; 80 percent brown (7.5YR 5/4) and 20 percent light brown (7.5YR 6/4) extremely gravelly sandy loam, brown (7.5YR 4/4) moist; massive; hard, firm, slightly sticky and moderately plastic; few fine roots; few fine tubular pores; many distinct calcium carbonate coatings on rock fragments; few fine gypsum crystals; 65 percent gravel; violently effervescent, 20 percent calcium carbonate equivalent; slightly alkaline (pH 7.8). (Combined thickness of the Bky and Bkyc horizons is 35 to 55 inches)
TYPE LOCATION: Cochise County, Arizona; located at a latitude of 31 degrees, 37 minutes, 33 seconds North and longitude of 110 degrees, 18 minutes, 30 seconds West.
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. Ustic aridic soil moisture regime.
Soil temperature: 62 to 69 degrees F.
Rock fragments: more than 35 percent gravel and/or petronodes
Petronodic feature: 20 to 50 percent petronodes. Thought to have formed from calcium and magnesium that precipitated out during fluctuating seasonal water tables under a climate much wetter than the present. Repeated wetting and extreme drying of the soil may have been a factor in nodule development. The petronodes have no internal organization and break down completely in HCl acid but not in water.
Reaction: slightly or moderately alkaline
Clay content: 5 to 18 percent
Depth to calcic horizon: 3 to 20 inches
A horizon
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 4 or 6, dry or moist
Texture: fine sandy loam, sandy loam
Calcium carbonate equivalent: 3 to 14 percent
Bk and Bky horizons
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 or 4, dry or moist
Texture: fine sandy loam, sandy loam
Calcium carbonate equivalent: 15 to 40 percent
Gypsum content: 0 to 5 percent
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Graveyard soils are on stream and fan terraces at elevations of 4,200 to 4,600 feet. Slopes range from 0 to 8 percent. These soils formed in mixed alluvium. The mean annual precipitation is 12 to 16 inches and occurs as thunderstorms during July to September and as gentle rains during December to February. The mean annual air temperature is 60 to 67 degrees F. The frost-free period is 180 to 230 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gulch, Libby, Bella, Vana, and Moco series. Gulch and Moco soils are fine-loamy. Libby soils are fine. Bella and Vana soils are shallow to a hardpan.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; slow to medium runoff; moderately rapid permeability.
USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Vegetation includes creosotebush, whitethorn, tarbush, black grama, sideoats grama, blue threeawn, slim tridens, false mesquite, range ratany, desert zinnia, and bush muhly.
DISTRIBUTION AND EXTENT: Southern Arizona. Graveyard soils are of moderate extent. MLRA is 41.
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 3 inches (A horizon)
Calcic horizon - The zone from 3 to 60 inches (Bk, Bkc, Bky, Bkyc', Bky' horizons)
Classified according to Soil Taxonomy Second edition, 1999