LOCATION IRAK COEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Cumulic Haplustolls
TYPICAL PEDON: Irak loam in pasture, (Colors are for dry soil unless otherwise noted.)
A1--0 to 8 inches; reddish brown (5YR 5/3) loam, dark reddish brown (5YR 3/3) moist; weak medium subangular blocky structure parting to weak fine granular; slightly hard, friable, slightly sticky and slightly plastic; slightly effervescent; slightly alkaline (pH 7.5); abrupt smooth boundary. (7 to 12 inches thick)
C1--8 to 13 inches; reddish brown (5YR 4/3) loam, dark reddish brown (5YR 3/3) moist; strong thick platy structure; hard, friable, slightly sticky and slightly plastic; slightly effervescent; slightly alkaline (pH 7.6); abrupt smooth boundary. (5 to 48 inches thick)
C2--13 to 43 inches; reddish brown (5YR 4/3) loam, dark reddish brown (5YR 3/3) moist; weak coarse prismatic structure parting to weak coarse subangular blocky; hard, friable, slightly sticky and slightly plastic; slightly effervescent; slightly alkaline (pH 7.5); clear smooth boundary. (8 to 45 inches thick)
C3--43 to 60 inches; reddish brown (5YR 4/3) loam, dark reddish brown (5YR 3/3) moist; weak medium subangular blocky structure; very hard, friable, slightly sticky and slightly plastic; slightly effervescent; slightly alkaline (pH 7.6).
TYPE LOCATION: Montezuma County, Colorado; about 2 miles west of the community of Yellow Jacket, located about 175 feet east and 750 feet south of the northwest corner of sec. 29, T. 38 N., R. 17 W.; Dolores East, Colorado quad; lat. 37 degrees 36 minutes 56 seconds N. and long. 108 degrees 45 minutes 16 seconds W., NAD27
RANGE IN CHARACTERISTICS:
Soil moisture regime: ustic bordering on aridic
Soil temperature regime: mesic
Mean annual soil temperature: 47 to 52 degrees F
Particle-size control section: 18 to 35 percent clay
with less than 15 percent fine sand and coarser and up to 35 percent very fine sand
Thickness of the mollic epipedon: 20 to 60 inches
Water table: depth is 1 to 3 feet, kind is apparent, months are April to September
A horizon:
Hue: 5YR or 7.5YR
Value: 3 to 5 (2 or 3 moist)
Chroma: 2 or 3
Rock fragments: 0 to 15
Calcium carbonate equivalent: 0 to 5 percent
Reaction: neutral to moderately alkaline
C horizon:
Hue: 5YR or 7.5YR
Value: 3 to 5 (2 to 4 moist)
Chroma: 2 to 4
Texture: loam or clay loam
Rock fragments: 0 to 15
Calcium carbonate equivalent: 1 to 5 percent
Reaction: neutral to moderately alkaline
COMPETING SERIES: These are the Ackmen, Alcester, Gabaldon, Muir, Shell, Tobin, and Trementina series. Potential competitors that do not yet have CEA class assigned are the Coleridge, Hord, Roxbury, and Vega series. Ackmen, Gabaldon, and Vega soils lack a water table from April through September. Alcester, Hord, Muir, Roxbury, Shell, Tobin, and Trementina soils have 10YR hues in some part of the profile. Coleridge soils lack carbonates above 40 inches and have a cambic horizon.
GEOGRAPHIC SETTING:
Parent material: alluvium derived from reworked eolian material
Landform: drainageways and draws
Slopes: 0 to 3 percent
Elevation: 6,200 to 7,400 feet
Mean annual temperature: 46 to 50 degrees F
Mean annual precipitation: 13 to 16 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 120 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ackmen, Pulpit, Sharps, and Wetherill series. Ackmen soils lack a water table from April through September. Pulpit, Sharps, and Wetherill soils have argillic horizons. In addition, Pulpit and Sharps soils have bedrock at a depth of 20 to 40 inches.
DRAINAGE AND PERMEABILITY: moderately well or somewhat poorly drained, negligible to medium runoff, moderate or moderately slow permeability
USE AND VEGETATION: Soils are used for livestock grazing, pasture, crops, and wildlife habitat. Native vegetation is alkali sacaton, western wheatgrass, inland saltgrass, and sedges.
DISTRIBUTION AND EXTENT: Southwest Colorado. LRR D, MLRA 36. This series is of small extent.
MLRA OFFICE RESPONSIBLE: Lakewood, Colorado
SERIES ESTABLISHED: Cortez Area, Colorado, Parts of Dolores and Montezuma Counties 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
mollic epipedon: The zone from 0 to 60 inches. (A, C1, C2, and C3)
Redoximorphic features: High chroma redox concentrations occur in the lower part of some pedons below 100 cm.
Water table: The presence of an apparent water table from 1 to 3 feet during the months of April to September.
Particle size control section: The zone from 10 to 40 inches. (C1, C2)
Soil Taxonomy Second Edition, 1999