LOCATION BISON AZEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Calcic Petrocalcids
TYPICAL PEDON: Bison gravelly loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 4 inches; brown (7.5YR 5/4) gravelly loam, reddish brown (5YR 4/4) moist; weak thick platy structure; soft, very friable, slightly sticky and slightly plastic; few very fine roots; many very fine tubular pores; 15 percent gravel; slightly effervescent; moderately alkaline (pH 8.0) abrupt smooth boundary. (2 to 5 inches thick)
Bw--4 to 8 inches; brown (7.5YR 5/4) gravelly loam, yellowish red (5YR 4/6) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few very fine roots; many very fine tubular pores; 15 percent gravel with lime coatings dominantly on the undersides; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (4 to 8 inches thick)
Bk1--8 to 13 inches; yellowish red (5YR 5/6) gravelly loam, yellowish red (5YR 4/6) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few very fine roots; many very fine tubular pores; 20 percent gravel with lime coatings dominantly on the undersides; violently effervescent, many large irregularly shaped soft lime masses; moderately alkaline (pH 8.2); clear wavy boundary. (5 to 20 inches thick)
Bk2--13 to 26 inches; pink (7.5YR 8/4) gravelly loam, reddish yellow (5YR 6/6) moist; strong fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few very fine roots; many very fine tubular pores; 20 percent gravel with lime coating dominantly on the undersides; violently effervescent, few fine soft lime masses; moderately alkaline (pH8.4); abrupt smooth boundary. (0 to 15 inches thick)
2Bkm--26 to 38 inches; pink (7.5YR 8/4) indurated lime cemented petrocalcic, reddish yellow (5YR 6/6) moist; massive; extremely hard, extremely firm; few very fine roots in fractures; abrupt wavy boundary. (8 to 30 inches thick)
3Bk--38 to 60 inches; yellowish red (5YR 5/6) gravelly loam, yellowish red (5YR 4/6) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; many very fine tubular pores; 25 percent lime coated gravel; weakly lime cemented; strongly effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Coconino County, Arizona; about 19 miles southwest of Marble Canyon; 2,500 feet north and 1,300 feet west of the southeast corner of Section 10, T. 37N., R. 4E.
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. Typic aridic soil moisture regime.
Soil temperature: 57 to 59 degrees F.
Clay content in control section: 10 to 18 percent
Rock fragments: 5 to 35 percent gravel and cobble above the hardpan
Carbonates: 5 to 35 percent calcium carbonate equivalent
Depth to calcic horizon: 6 to 13 inches
Depth to petrocalcic: 20 to 40 inches
A horizon
Hue: 5YR, 7.5YR
Value: 5 or 6 dry, 4 or 5 moist
Bw horizon
Hue: 5YR, 7.5YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 4 or 6, dry and moist
Bk horizon
Hue: 5YR, 7.5YR
Value: 5 through 8 dry, 4 through 7 moist
Chroma: 3 through 6, dry and moist
Bkm horizon
Thickness: 8 to 30 inches
3Bk horizon
Texture: loam, sandy loam
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Bison soils are on fan terraces at elevations of 3,600 to 4,400 feet. They formed in alluvium from limestone. Slopes range from 2 to 6 percent. Mean annual precipitation is 7 to 11 inches. Mean annual air temperature is about 55 to 57 degrees F. The frost-free period is 165 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Curob, Clayhole, Kinan, Pennell, Monue and Seeg soils. Curob soils are shallow to a hardpan. Pennell soils are shallow to bedrock. Clayhole, Kinan, Monue and Seeg soils are very deep.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderately rapid permeability.
USE AND VEGETATION: Used mainly for livestock grazing. Present vegetation is galleta, sand dropseed, blue grama and fourwing saltbush.
DISTRIBUTION AND EXTENT: Northern Arizona. The Bison series is of moderate extent. MLRA 35.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Coconino County, Arizona; Soil survey of Coconino County Area, Arizona, North Kaibab Part; 1991.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 4 inches (A horizon)
Calcic horizon - the zone from 8 to 26 inches (Bk horizons)
Petrocalcic horizon - the zone from 26 to 38 inches (2Bkm horizon)
Classified according to Soil Taxonomy Second Edition, 1999.