LOCATION REDTOM COEstablished Series
TAXONOMIC CLASS: Sandy, mixed, frigid Alfic Argiustolls
TYPICAL PEDON: Redtom sandy loam - grassland. (Colors are for dry soil unless otherwise noted.)
A--0 to 11 inches; brown (7.5YR 4/2) sandy loam, very dark brown (7.5YR 2/2) moist; moderate very fine granular structure; soft, very friable, nonsticky and nonplastic; 5 percent fine and very fine angular granite gravel; neutral (pH 6.7); clear smooth boundary. (7 to 15 inches thick)
E--11 to 17 inches; light reddish brown (5YR 6/3) loamy sand, reddish brown (5YR 4/3) moist; weak thick platy structure parting to weak medium subangular blocky; hard, very friable, nonsticky and nonplastic; 5 to 10 percent fine and very fine angular granitic gravel; neutral (pH 6.7); clear smooth boundary. (3 to 12 inches thick)
E and Bt--17 to 22 inches; light reddish brown (5YR 6/3) loamy sand, reddish brown (5YR 4/3) moist; weak medium subangular blocky structure; hard, very friable, nonsticky and nonplastic; contains nodules and dark reddish brown (2.5YR 3/4) 1/16 to 1/4 inch thick lamellea of sandy clay loam; faint patchy clay films on aggregate faces in the lamellae; 5 percent fine and very fine angular granite gravel; neutral(pH 6.7); gradual wavy boundary.
Bt and E--22 to 40 inches; red (2.5YR 5/6) loamy sand, reddish brown (2.5YR 4/4) moist; single grain; loose, nonsticky and nonplastic; contains 1/2 to 1 inch thick lamellae of sandy clay loam; moderate medium subangular blocky structure in lamellae; lamellae are very hard, very friable; faint nearly continuous clay films on aggregate faces in the lamellae; slightly acid (pH 6.4); diffuse wavy boundary. (combined E and Bt, Bt and E is 12 to 40 inches thick)
C--40 to 60 inches; red (2.5YR 5/6) loamy sand, red (2.5YR 4/6) moist; single grain; loose, nonsticky and nonplastic; 5 to 10 percent fine and very fine angular granite gravel; slightly acid (pH 6.4).
TYPE LOCATION: Douglas County, Colorado, 600 feet south and 600 feet east of the northwest corner of the southeast quarter of Sec. 25, T. 9 5., R. 68 W.
RANGE IN CHARACTERISTICS:
Soil moisture: typic ustic regime and subclass
Mean annual soil temperature: 44 to 46 degrees F.
Mean summer soil temperature: about 62 degrees F.
Thickness of mollic epipedon: 10 to 16 inches
Base saturation: 60 to 100 percent
Depth to the argillic horizon: less than 24 inches
Depth to the base of the argillic horizon: 17 to 55 inches
Rock fragments: range from 0 to 35 percent by volume in a major part of the solum and C horizon and are mainly less than 3 inches in diameter but range from 1/8 to 10 inches in diameter.
Carbonate content: typically noncalcareous for more than 60 inches but must be noncalcareous for more than 40 inches, or are noncalcareous for at least the upper 3 inches of the C horizon if the solum exceeds 40 inches.
A horizon:
Hue: 5YR to 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 1 through 3, dry or moist
Texture: sandy loam or loamy sand
Reaction: slightly acid to slightly alkaline
E horizon (albic horizon):
Hue: 2.5YR to 7.5YR
Value: 5 through 8 dry, 4 through 7 moist
Chroma: 1 through 4, dry or moist
Texture: loamy sand or sand
Reaction: slightly acid to slightly alkaline
E and Bt, Bt and E horizons:
Hue: 10R to 5YR; Subhorizons yellower than 5YR may occur in some pedons
Value: 5 through 7 dry, 4 through 6 moist
Chroma: 1 through 6, dry or moist
Texture: loamy sand in which lamellae of sandy clay loam or sandy loam occur. If mixed proportionally to their occurrence in the horizon the composite soil texture should not exceed a loamy coarse sand.
Sand fraction: a large proportion is medium, coarse, and very coarse angular sand which has a high percentage of flat bearing surfaces, between sand grains.
Reaction: slightly acid to slightly alkaline
C horizon:
Hue: 5YR through 10R
Texture: loamy sand or loamy coarse sand.
Reaction: slightly acid to slightly alkaline
COMPETING SERIES: There are no competeting series currently recognized. A soil in a related family is the Lonetree series. Lonetree soils do not have lamellae.
GEOGRAPHIC SETTING: The Redtom soils are on gently to moderately sloping hills, ridges, valley side slopes, and alluvial fans. Parent sediments were derived and locally transported from reddish brown arkosic sedimentary beds of the Fountain and Lyons formations. Elevation is 6,400 to 7,000 feet. The frost free season is 125 days or less. The average annual precipitation is 17 to 19 inches, with peak periods of precipitation occurring in the spring and early summer months.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gove and Lonetree soils. Gove soils have soil temperature warmer than 47 degrees F. Lonetree soils are coarse textured and lack albic horizons.
DRAINAGE AND PERMEABILITY: Well to somewhat excessively drained; low runoff; rapid permeability.
USE AND VEGETATION: Native vegetation is mainly scattered ponderosa pine with Gambels oak, mountain mahogany, and mid and tall grasses. These soils are used primarily as native pastureland.
DISTRIBUTION AND EXTENT: The foothill areas of east-central Colorado. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: The Castle Rock Area, Douglas County, Colorado, 1975.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Series control section: The zone from 0 to 60 inches.
Particle-size control section: The zone from 10 to 40 inches. (part of the E, the E and Bt, Bt and E horizons)
Mollic epipedon: from 0 to 11 inches. (A horizon)
Albic horizon: from 11 to 17 inches. (E horizon)
Argillic horizon: the cumulative thickness of lamellae from 17 to 40 inches exceeds 15cm. (E and Bt, Bt and E horizons)
The 2/2006 revision replaced the old pedon description with an updated description from the Castle Rock Area soil survey (the series type location). The classification was also revised from coarse-loamy to sandy.