LOCATION PAHLOW WYEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, mixed, frigid Ustic Haplocalcids
TYPICAL PEDON: Pahlow gravelly sandy loam on a concave, west-facing slope of one percent with native grass vegetation - utilized as rangeland. (Colors are for dry soil unless otherwise stated.) The surface has 25 percent fine and medium pebbles.
A--0 to 3 inches; brown (10YR 4/3) gravelly sandy loam, dark brown (10YR 3/3) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many fine and medium roots; many very fine discontinuous pores; 15 percent pebbles; mildly alkaline (pH 7.8); abrupt smooth boundary. (3 to 5 inches thick)
Bw1--3 to 7 inches; brown (10YR 5/3) very gravelly sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; many fine and few medium roots; many very fine discontinuous pores; 35 percent pebbles, 5 percent cobbles; mildly alkaline (pH 7.8); clear smooth boundary. (4 to 19 inches thick)
Bw2--7 to 15 inches; dark yellowish brown (10YR 4/4) very gravelly sandy loam, brown (10YR 4/3) moist; weak fine subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common fine roots; common very fine and fine continuous pores; noneffervescent matrix with carbonates as few thin crusts on undersides of coarse fragments; 40 percent pebbles, 10 percent cobbles; mildly alkaline (pH 7.8); clear smooth boundary. (0 to 10 inches thick)
2Bk1--15 to 25 inches; pale brown (10YR 6/3) very gravelly loamy sand, brown (10YR 5/3) moist; massive; loose, loose, nonsticky and nonplastic; very few fine roots; many very fine and fine, continuous pores; effervescent; carbonates disseminated and as common moderately thick pendants and crusts on undersides of larger coarse fragments; 50 percent pebbles; 5 percent cobbles; moderately alkaline (pH 7.9); gradual smooth boundary. (7 to 30 inches thick)
2Bk2--25 to 60 inches; pale brown (10YR 6/3) extremely gravelly loamy sand, brown (10YR 5/3) moist; massive; loose, loose, nonsticky and nonplastic; very few fine roots; many very fine and fine continuous pores; violently effervescent, carbonates disseminated and as common moderately thick pendants and crusts on undersides of coarse fragments; 50 percent pebbles, 10 percent cobbles; moderately alkaline (pH 8.0).
TYPE LOCATION: Albany County, Wyoming; 1,525 feet west and 1,625 feet south of the northeast corner of section 30, T14N,R76W.
RANGE IN CHARACTERISTICS: Depth to the base of the cambic horizon and horizons of continuous carbonate accumulations ranges from 12 to 26 inches. The mean annual soil temperature is 40 to 47 degrees F, and the mean summer soil temperature is 59 to 65 degrees F. The particle-size control section has a loamy-skeletal Bw and, if present, Bk1 horizon over a noncontrasting sandy-skeletal 2Bk horizon. When averaged, the particle-size control section is sandy-skeletal with 3 to 13 percent clay, 35 to 70 percent pebbles, and 5 to 25 percent cobbles. Subdivision of both the Bw and 2Bk horizons is common but not a requirement for the series.
The A horizon has hue of 10YR or 7.5YR, value of 4 or 5 dry, 3 or 4 moist, and chroma of 2 through 4. Coarse fragments range from 0 to 40 percent pebbles and 0 to 5 percent cobbles. Reaction is mildly or moderately alkaline.
The Bw horizon has hue of 10YR or 7.5YR, value of 4 or 5 dry, 3 through 5 moist, and chroma of 3 through 5. Texture of the matrix is sandy loam with 5 to 18 percent clay modified with 20 to 50 percent pebbles and 5 to 15 percent cobbles. Reaction is mildly or moderately alkaline.
The Bk horizon, when present, has hue of 10YR or 7.5YR, value of 5 or 6 dry, 4 or 5 moist, and chroma of 2 through 4. Texture is the same as the Bw horizon. Carbonates range from 5 to 15 percent. Reaction is mildly alkaline (pH 7.8) or moderately alkaline.
The 2Bk horizon has hue of 10YR or 7.5YR, value of 5 through 7 dry, 5 or 6 moist, and chroma of 3 through 5. Texture of the matrix is loamy sand and less typically sand with 0 to 10 percent clay, 40 to 70 percent pebbles, and 5 to 25 percent cobbles. Carbonates range from 10 to 25 percent with the majority occurring as moderately thick pendants on coarse fragments. Reaction is moderately or strongly alkaline.
COMPETING SERIES: This is the Folavar and Shurley(T) series. Folavar soils are noncalcareous. Shurley soils contain from 20 to 50 percent flagstones throughout the major part of the control section.
GEOGRAPHIC SETTING: Pahlow soils are on alluvial flats and terraces with mounded microrelief. Mounds are a result of frost heaving in an ancient periglacial environment. Pahlow soils occupy both the mounds and intermounded areas. Slopes are 0 to 3 percent. Elevations are 7,000 to 7,800 feet. The mean annual precipitation ranges from 10 to 15 inches with peak periods occurring in April, May, and early June. The frost-free season is 85 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Fola and Grayville soils. Fola soils are free of carbonates above 40 inches. Grayville soils occur in mounds and lack the contrasting sand or loamy sand above 40 inches.
DRAINAGE AND PERMEABILITY: Well drained; slow or medium runoff; rapidly permeable. In some areas along irrigation ditches and pastures a water table is present during the irrigation season.
USE AND VEGETATION: Pahlow soils are used for rangeland and wildlife habitat. In some areas the soils are also used for irrigated hay and pasture. Native vegetation is needleandthread grass, thickspike wheatgrass, Indian ricegrass, and threadleaf sedge.
DISTRIBUTION AND EXTENT: Southeastern Wyoming. The soil is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Albany County (Albany County Area), Wyoming; 1991.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 1 inch (A).
Cambic horizon - 1 to 15 inches (Bw, Bw2).
Calcic horizon - 15 to 40 inches (2Bk, 2Bk2).
Borollic feature - Organic carbon and soil temperature regime meets the requirements for Borollic.
The calcic horizon is identified by crusts and pendants on coarse fragments. Most of the carbonates have accumulated on pebbles 1 to 3 inches in diameter and in the upper part of the calcic horizon. The carbonates do not appear to accumulate on smaller pebbles. The amount of carbonate accumulation was not observed to decrease within 60 inches.