LOCATION COMODORE                CO+UT

Established Series
Rev. GB/AJS/JWB
04/2011

COMODORE SERIES

The Comodore series consists of shallow, well drained soils that formed in gravelly colluvium over residuum derived from granite, gneiss, and mica schist. Comodore soils are on hills, ridges and mountain slopes. Slopes range from 4 to 70 percent. The mean annual precipitation is about 14 inches and the mean annual air temperature is about 42 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Aridic Lithic Haplustolls

TYPICAL PEDON: Comodore very stony loam, grassland. (Colors are for dry soil unless otherwise noted)

A--0 to 9 inches; grayish brown (10YR 5/2) very stony loam, very dark brown (10YR 2/2) moist; weak fine subangular blocky structure parting to fine granular; soft, very friable, slightly sticky, slightly plastic; 60 percent stones; slightly acid; clear smooth boundary. (6 to 16 inches thick)

C--9 to 13 inches; brown (10YR 5/3) extremely stony loam, brown (10YR 4/3) moist; massive; slightly hard, very friable, slightly sticky, slightly plastic; 70 percent stones; slightly acid; abrupt smooth boundary. (4 to 14 inches thick)

R--13 to 17 inches; hard igneous and metamorphic bedrock.

TYPE LOCATION: Alamosa County, Colorado; approximately 1/4 mile west of the southeast corner, sec. 9, T. 28 S., R. 73 W.

RANGE IN CHARACTERISTICS:
Soil moisture:
Soil moisture regime subclass: aridic (torric)
Soil moisture regime class: ustic
Mean annual soil temperature: 41 to 46 degrees F (5 to 7.8 degrees C)
Mean summer soil temperature: 63 to 66 degrees F (17.2 to 18.9 degrees C)
Base saturation ranges from 60 to 100 percent.
Depth to the lithic contact: 10 to 20 inches.
Thickness of mollic epipedon: 5 to 16 inches (25 to 40 centimeters)
The particle control section is usually very stony, extremely stony, extremely cobbly loam, or very cobbly loam, sandy clay loam, or clay loam.
Rock fragments can range from 35 to 85 percent and the size range is 10 to 36 inches in diameter.
Some pedons have rock fragments less than 10 inches diameter, with 15 to 20 percent pebbles and 10 to 15 percent cobbles.
A and C horizons range from slightly acid to slightly alkaline

Particle-size control section (weighted average):
Clay content: 18 to 27 percent
Sand content: 20 to 70 percent
Silt content: 5 to 55 percent
Rock fragment content: 35 to 85 percent

A horizon:
Hue: 7.5YR to 2.5Y
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 1 to 3
Texture: very cobbly loam, very stony loam, stony loam
Clay content: 12 to 27 percent
Carbonate clay content: 0 to 1 percent
Sand content: 32 to 63 percent
Silt content: 15 to 50 percent
Fragment content, total: 15 to 55 percent
Fragment size and content: 10 to 30 percent indurated gravel
15 to 25 percent indurated cobbles
0 to 30 percent indurated stones
Calcium carbonate equivalent: 0 to 2 percent
Electrical conductivity: 0 to 2 mmhos/cm
Reaction: pH 6.6 to 7.8
Organic matter content: 1.0 to 2.0 percent

Bw or C horizon:
Hue: 7.5YR, to 2.5Y
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 2 to 4
Texture: extremely cobbly loam, very cobbly loam, very stony loam
Clay content: 18 to 27 percent
Carbonate clay content: 0 to 1 percent
Sand content: 32 to 63 percent
Silt content: 15 to 50 percent
Fragment content, total: 35 to 75 percent
Fragment size and content: 25 to 50 percent indurated gravel
10 to 35 percent indurated cobbles
0 to 30 percent indurated stones
Calcium carbonate equivalent: 0 to 2 percent
Electrical conductivity: 0 to 2 mmhos/cm
Reaction: pH 6.6 to 7.3
Organic matter content: 1.0 to 1.5 percent

COMPETING SERIES: These are the Reedpoint series.
Reedpoint soils are very shallow and have channers and flagstone sized sandstone fragments.

GEOGRAPHIC SETTING:
Parent material: colluvium over residuum derived from granite, gneiss, and mica schist.
Landform: on hills, ridges and mountain slopes.
Slope: 4 to 70 percent.
Mean annual air temperature: 37 to 45 degrees F.
Mean annual precipitation: 12 to 16 inches.
Frost-free period ranges from 60 to 90 days.
Seasonal pattern: The soil moisture control section is affected by snow melt in early spring and peak precipitation is in the form of thunderstorms from June to September.
Elevation ranges: 8,000 to 10,500.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Firo soils and Uracca soils. Uracca soils have argillic horizons and lack bedrock above depth of 20 inches.

DRAINAGE AND PERMEABILITY: Well drained to excessively drained; runoff is rapid; permeability is moderate above the bedrock.

USE AND VEGETATION: These soils are used principally as native pastureland or for recreational purposes. Principal native vegetation is mainly twoneedle pinyon pine, juniper, blue grama, wax current, mountain muhly, fringe sage, and mountainmahogany.

DISTRIBUTION AND EXTENT: Mountainous areas of south central Colorado surrounding the Alamosa Basin. The series is of moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Alamosa County, Colorado, 1974.

Remarks: Diagnostic horizons recognized in this pedon are;
Mollic epipedon: 0 to 9 inches
Lithic contact: 13 inches
Comodore soils usually are noncalcareous throughout but can have thin discontinuous calcareous subhorizons just above the bedrock in some pedons.
The Comodore series has been mapped too broad in the past. Comodore is Aridic Ustic and will be restricted to areas with Pinyon pine, Rocky Mountain juniper and grasses.
Last updated by the state 2/99.

Taxonomic Version: Eleventh edition, 2010.

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National Cooperative Soil Survey
U.S.A.