LOCATION PYEATT AZEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, thermic Aridic Calciustolls
TYPICAL PEDON: Pyeatt gravelly loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 3 inches; brown (7.5YR 4/3) gravelly loam, dark brown (7.5YR 3/3) moist; moderate thin platy structure; soft, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common fine irregular pores; 20 percent gravel; strongly effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (1 to 6 inches thick)
Bk1--3 to 9 inches; brown (7.5YR 4/2) gravelly loam, dark brown (7.5YR 3/2) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine and fine roots; few fine tubular pores; common distinct calcium carbonate coatings on undersides of rocks; few fine calcium carbonate filaments; 20 percent gravel; strongly effervescent, 8 percent calcium carbonate equivalent; moderately alkaline (pH 8.0); clear smooth boundary.
Bk2--9 to 35 inches; brown (7.5YR 5/3) gravelly fine sandy loam, brown (7.5YR 4/3) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common fine roots; few fine irregular and tubular pores; many distinct calcium carbonate coatings on rock fragments; few fine calcium carbonate filaments; 18 percent gravel; violently effervescent, 20 percent calcium carbonate equivalent; moderately alkaline (pH 8.0); clear smooth boundary.
Bk3--35 to 41 inches; light brown (7.5YR 6/3) fine sandy loam, brown (7.5YR 4/3) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few fine roots; few fine irregular and tubular pores; common distinct calcium carbonate coatings on rock fragments; common fine and medium calcium carbonate filaments; 10 percent gravel; violently effervescent, 23 percent calcium carbonate equivalent; moderately alkaline (pH 8.2); clear smooth boundary.
Bk4--41 to 60 inches; pink (7.5YR 7/3) and brown (7.5YR 5/3) fine sandy loam, brown (7.5YR4/3) moist; weak medium subangular blocky structure; very soft, very friable, slightly sticky and slightly plastic; few fine roots; few fine irregular pores; few distinct calcium carbonate coatings on rock fragments; common fine and medium calcium carbonate filaments; 10 percent gravel; violently effervescent, 30 percent calcium carbonate equivalent; moderately alkaline (pH 8.2); clear smooth boundary. (Combined thickness of the Bk horizons is 30 to 57 inches)
TYPE LOCATION: Fort Huachuca, Arizona; located at a latitude of 31 degrees, 36 minutes, 30 seconds North and longitude of 110 degrees, 23 minutes, 20 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. Aridic ustic soil moisture regime.
Soil Temperature: 59 to 64 degrees F.
Rock fragments: less than 35 percent
Organic matter content: 1 to 2 percent
Clay content: less than 18 percent
Depth to calcic horizon: 3 to 20 inches
Reaction: slightly or moderately alkaline
Effervescence: strong or violent
A horizon
Hue: 10YR, 7.5YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 2 or 3, dry or moist
Calcium carbonate equivalent: 0 to 10 percent
Bk horizon
Hue: 10YR, 7.5YR
Value: 4 through 8 dry, 3 through 7 moist
Chroma: 2 or 3, dry or moist
Texture: sandy loam, fine sandy loam, loam
Calcium carbonate equivalent: 10 to 30 percent
COMPETING SERIES: These are the Fowlkes (TX) and Oklark (OK) series. Fowkles soils are moderately deep to a paralithic contact. Oklark soils have mean annual precipitation of 20 to 26 inches, are in MLRA 77 and are moist in May and June.
GEOGRAPHIC SETTING: Pyeatt soils are on fan terraces at elevations of 4800 to 5,800 feet. Slopes range from 1 to 40 percent. These soils formed in fan alluvium from mixed calcareous sources. The mean annual precipitation is 16 to 20 inches and occurs as thunderstorms during July to September and as gentle rains during December and January. The mean annual air temperature is 57 to 62 degrees F. The frost-free period is 160 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gardencan, Terrarossa, Blacktail and Lanque series. Gardencan, Terrarossa and Blacktail soils have argillic horizons. Lanque soils do not have a calcic horizon.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderate permeability.
USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Vegetation includes sideoats grama, black grama, rough tridens, New Mexico feathergrass, threeawn, perennial forbs, ratany, false mesquite, sacahuista, Parry agave and one-seeded juniper.
DISTRIBUTION AND EXTENT: Southern Arizona. Pyeatt soils are of moderate extent. MLRA is 41. Name derived from the Pyeatt Ranch.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Cochise County, Arizona; Soil survey of Cochise County, AZ, Douglas-Tombstone Part; 1996.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from 0 to 9 inches (A, Bk1 horizons)
Calcic horizon - The zone from 3 to 60 inches (Bk1, Bk2, Bk3, Bk4 horizons)
Soil Taxonomy Second Edition, 1999