LOCATION PRATER COEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Aridic Haplustalfs
TYPICAL PEDON: Prater loam, on an east facing, 22 percent slope in pinyon juniper woodland at an elevation of 7,560 feet. (Colors are for dry soil unless otherwise noted.) The surface is covered by 8 percent gravel, 3 percent cobbles, and 2 percent stones.
A1--0 to 1 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; massive; loose, loose, nonsticky and nonplastic; 5 percent gravel, 5 percent cobbles, and 1 percent stones; neutral (7.0); abrupt smooth boundary. (1 to 6 inches thick)
A2--1 to 3 inches; brown (10YR 5/3) clay loam, dark brown (10YR 3/3) moist; moderate coarse platy structure parting to moderate fine granular; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots throughout; 5 percent gravel, 5 percent cobbles, and 1 percent stones; neutral (7.0); abrupt smooth boundary (2 to 6 inches thick)
Bt--3 to 9 inches; yellowish brown (10YR 5/4) clay loam, brown (10YR 4/3) moist; moderate fine angular blocky structure; hard, friable, moderately sticky and moderately plastic; common fine roots between peds and common medium roots throughout; few very fine discontinuous tubular pores; common distinct discontinuous clay films on faces of peds and in pores; 5 percent gravel, 5 percent cobbles, and 1 percent stones; neutral (7.0); gradual smooth boundary. (4 to 16 inches thick)
Btk1--9 to 17 inches; yellowish brown (10YR 5/4) clay loam, brown (10YR 4/3) moist; few medium faint yellowish brown (10YR 5/6) mottles; moderate fine angular blocky structure; very hard, friable, moderately sticky and moderately plastic; common fine and coarse roots throughout; few very fine and fine discontinuous tubular pores; many distinct continuous clay films on faces of peds and in pores; few fine rounded soft masses of carbonate throughout; slightly effervescent; 5 percent gravel, 5 percent cobbles, and 1 percent stones; slightly alkaline (7.6); gradual smooth boundary. (4 to 12 inches thick)
Btk2--17 to 21 inches; light yellowish brown (10YR 6/4) clay loam, brown (10YR 4/3) moist; common medium faint yellowish brown (10YR 5/6) mottles; moderate fine angular blocky structure; very hard, friable, moderately sticky and moderately plastic; few very fine and common fine roots throughout; few very fine and fine discontinuous tubular pores; many distinct continuous clay films on faces of peds and in pores; common medium rounded soft masses of carbonate throughout; strongly effervescent; 5 percent gravel, 5 percent cobbles, and 1 percent stones; moderately alkaline (pH 8.2); gradual smooth boundary. (3 to 12 inches thick)
Btk3--21 to 37 inches; very pale brown (10YR 7/3) clay, brown (10YR 5/3) moist; common fine faint yellowish brown (10YR 5/6) mottles; moderate fine angular blocky structure; very hard, friable, moderately sticky and moderately plastic; few very fine and common fine roots throughout; few very fine discontinuous tubular pores; many distinct continuous clay films on faces of peds and in pores; common coarse irregular soft masses of carbonate throughout; strongly effervescent; 5 percent gravel, 4 percent cobbles, and 2 percent stones; moderately alkaline (pH 8.2); gradual smooth boundary. (0 to 20 inches thick)
Bk--37 to 60 inches; 50 percent light gray (10YR 7/2), 25 percent light yellowish brown (10YR 6/4), and 25 percent brown (10YR 5/3) clay, grayish brown (10YR 5/2), yellowish brown (10YR 5/4), and grayish brown (10YR 5/2) moist; few fine faint yellowish brown (10YR 5/6) mottles; weak coarse subangular blocky structure; extremely hard, friable, slightly sticky and moderately plastic; common very fine, few fine, and common medium roots throughout; common coarse rounded soft masses of carbonate throughout; slightly effervescent; 5 percent gravel, 5 percent cobbles, and 4 percent stones; moderately alkaline (pH 8.2). Pressure faces present. Horizon has variegated colors. Pockets of eolian material at a depth of 42 inches. (4 to 30 inches thick)
TYPE LOCATION: Montezuma County, Colorado; about 3 miles south of Morefield Campground; located about 1,500 feet west and 300 feet south of the northeast corner of sec. 32, T. 35 N., R. 14 W.; Point Lookout, Colorado USGS quad; lat. 37 degrees 15 minutes 07 seconds N. and long. 108 degrees 24 minutes 45 seconds W., NAD27
RANGE IN CHARACTERISTICS:
Soil moisture regime: ustic bordering on aridic
Soil temperature regime: mesic
Mean annual soil temperature: 40 to 44 degrees F
Surface rock fragments: 0 to 15 percent
Depth to secondary calcium carbonate: 6 to 40 inches
Vertic features: pressure faces on peds below 40 inches
Particle-size control section:
Clay content: 35 to 50 percent
A horizon:
Hue: 7.5YR or 10YR
Value: 4 to 6 (3 to 5 moist)
Chroma: 2 to 4
Texture: clay loam, or loam
Rock fragments: 10 to 20 percent
Calcium carbonate equivalent: 0 to 5 percent
Reaction: neutral
Bt horizon:
Hue: 10YR or 2.5Y
Value: 4 to 7 (3 to 6 moist)
Chroma: 2 to 4
Texture: clay loam or clay
Rock fragments: 5 to 20 percent
Calcium carbonate equivalent: 1 to 10 percent
Reaction: neutral to moderately alkaline
COMPETING SERIES: These are the Durango, Erramouspe, Fikel, Hosta, Hualapai, Jacee, Montecito, Nogal, Paguate, Teco, Tinian and Wilmac series. Durango soils are 7.5YR and redder in the Bt horizon. Erramouspe, Hualapai, Jacee, Nogal, Paguate, Tinian, and Wilmac soils are moderately deep. Hosta soils contain less than 5 percent coarse fragments in any horizon. Montecito and Teco soils have a calcic horizon and would be reclassified as Calcidic Haplustalfs.
GEOGRAPHIC SETTING:
Parent material: colluvium, slope alluvium, and alluvium derived from sandstone and shale
Landform: canyons, hills, and alluvial fans
Slopes: 10 to 60 percent
Elevation: 6,800 to 7,800 feet
Mean annual temperature: 47 to 50 degrees F
Mean annual precipitation: 16 to 19 inches
Precipitation is fairly evenly distributed throughout the year with July and August being slightly wetter and June being slightly dryer.
Frost-free period: 130 to 150 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Wauquie, Dolcan, Arabrab, and Longburn series. Wauquie soils have more than 35 percent coarse fragments in the control section. Dolcan, Arabrab, and Longburn soils all have bedrock within 20 inches of the surface.
DRAINAGE AND PERMEABILITY: well drained, very high runoff, slow permeability
USE AND VEGETATION: These soils are used for wildlife habitat. Native vegetation is pinyon, juniper, oakbrush, and mountainmahogany.
DISTRIBUTION AND EXTENT: Southwest Colorado. LRR D, MLRA 36. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Cortez Area, Colorado, Parts of Dolores and Montezuma Counties 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 3 inches. (A1 and A2)
Argillic horizon: The zone from 3 to 37 inches. (Bt, Btk1, Btk2, and Btk3)
Vertic features: Pressure faces exist in some pedons below 20 inches.
Particle-size control section: The zone from 3 to 23 inches. (Bt, Btk1, Btk2, Btk3)
Mottles are weathered coarse fragments, iron nodules from parent sandstone.
Soil Taxonomy Second Edition, 1999