LOCATION ACKMEN UT+CO IDEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Cumulic Haplustolls
TYPICAL PEDON: Ackmen silt loam on rangeland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 3 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; weak thin platy structure parting to weak medium granular; soft, very friable, slightly sticky and slightly plastic; few fine, medium, and coarse roots; few pores; slightly alkaline (pH 7.6); clear smooth boundary. (2 to 5 inches thick)
A2--3 to 7 inches; brown (10YR 4/3) silt loam, very dark brown (10YR 2/2) moist; weak thick platy structure parting to weak medium granular; hard, friable, slightly sticky and slightly plastic; many fine and few medium and coarse roots; few fine pores; slightly alkaline (pH 7.5); clear wavy boundary. (3 to 9 inches thick)
A3--7 to 32 inches; brown (7.5YR 4/2) loam, dark brown (7.5YR 3/2) moist; weak medium and coarse prismatic structure parting to very fine subangular blocky; very hard, friable, slightly sticky and moderately plastic; few fine, medium and coarse roots; many fine and few medium pores; slightly alkaline (pH 7.7); gradual wavy boundary. (12 to 25 inches thick)
C--32 to 71 inches; brown (7.5YR 4/2) loam, dark brown (7.5YR 3/2) moist; massive; very hard, friable, moderately sticky and moderately plastic; few roots; slightly alkaline (pH 7.4).
TYPE LOCATION: San Juan County, Utah; about 0.9 miles east of Peter Spring, south side of road; NE 1/4 of sec. 25, T. 32 S., R. 23 E.
RANGE IN CHARACTERISTICS:
Soil moisture regime: ustic bordering on aridic
Soil temperature regime: mesic
Mean annual soil temperature: 47 to 53 degrees F
Particle-size control section: 18 to 27 percent clay
Thickness of the mollic epipedon: 20 to 36 inches
A horizon:
Hue: 7.5YR or 10YR
Value: 3 to 5 (2 or 3 moist)
Chroma: 1 to 4
Texture: silt loam, loam, clay loam, silty clay loam, or silty clay
C horizon:
Hue: 7.5YR or 10YR
Value: 3 to 5 (2 to 4 moist)
Chroma: 2 to 6
Texture: loam, fine sandy loam, clay loam, or sandy clay loam
Calcium carbonate equivalent: 0 to 5 percent
Reaction: slightly or moderately alkaline
COMPETING SERIES: These are the Alcester, Gabaldon, Irak, Muir, Shell, Tobin, and Trementina series. Potential competitors that do not yet have CEA class assigned are the Coleridge, Hord, Roxbury, and Vega series. Alcester soils have A1 horizons 14 to 20 inches thick and lack stratification. Gabaldon soils are calcareous throughout and have a cambic horizon. Hord, Coleridge, Muir, Shell, and Tobin soils are all Typic Ustic with mean annual precipitation of 25 to 30 inches. Irak soils have a water table at 1 to 3 feet during part of the year. Roxbury soils have carbonates at depths of less than 15 inches. Vega soils have 28 to 35 percent clay in the series control section. Trementina soils have carbonates at depths between 15 and 30 inches.
GEOGRAPHIC SETTING:
Parent material: alluvium derived from intrusive igneous rocks, mixed sedimentary rocks, and surface soil material eroded from adjoining uplands.
Landform: flood plains, drainageways, valleys, draws, and alluvial fans
Slopes: 0 to 20 percent
Elevation: 6,000 to 7,500 feet
Mean annual temperature: 46 to 52 degrees F
Mean annual precipitation: 13 to 18 inches
Precipitation is fairly evenly distributed throughout the year with July and August being slightly wetter and June being slightly dryer.
Frost-free period: 100 to 150 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Abajo, Monticello, and Northdale soils. Monticello and Northdale soils have Bt horizons with hue of 5YR. Northdale soils have horizons of carbonate accumulation. Abajo soils have clay argillic horizons.
DRAINAGE AND PERMEABILITY: well drained, negligible to high runoff, moderate permeability
USE AND VEGETATION: Used mainly for dryland and irrigated cropland. The native vegetation is mainly western wheatgrass, native bluegrass, junegrass, big sagebrush, rabbit brush, and Gambel oak.
DISTRIBUTION AND EXTENT: Southeast Utah and southwest Colorado. LRR D, MLRA 36 and 39. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: San Juan Area, Utah. 1952.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
mollic epipedon: The zone from 0 to 32 inches. (A1, A2, and A3)
Particle size control section: The zone from 10 to 40 inches. (A3, C)
Soil Taxonomy Second Edition, 1999