LOCATION COWBOY COEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Leptic Haplogypsids
TYPICAL PEDON: Cowboy silty clay on a northwest facing, 7 percent slope in rangeland at an elevation of 5,100 feet. (Colors are for dry soil unless otherwise noted.) The surface is covered with 8 percent gravel, 2 percent cobble and 1 percent stone.
A--0 to 2 inches; light olive brown (2.5Y 5/4) silty clay, light olive brown (2.5Y 5/3) moist; strong very fine granular structure; soft, very friable, moderately sticky and moderately plastic; many very fine roots throughout; 2 percent calcium carbonate equivalent; 5 percent sandstone gravel; slightly effervescent; moderately alkaline (pH 8.1); abrupt wavy boundary. (2 to 10 inches thick)
BA--2 to 5 inches; light yellowish brown (2.5Y 6/4) silty clay, light olive brown (2.5Y 5/3) moist; moderate very coarse prismatic structure parting to moderate very thick platy; hard, very firm, very sticky and very plastic; few fine roots between peds and common very fine roots throughout; few fine and few very fine dendritic tubular pores; few fine irregular carbonate masses; few fine irregular gypsum crystals and few medium irregular nests of gypsum; 2 percent calcium carbonate equivalent; 3 percent gypsum; 3 percent sandstone gravel; slightly effervescent; moderately alkaline (pH 8.0); clear wavy boundary.
By1--5 to 19 inches; light yellowish brown (2.5Y 6/4) clay, light olive brown (2.5Y 5/3) moist; strong very coarse prismatic structure parting to moderate medium and coarse subangular blocky; very hard, extremely firm, very sticky and very plastic; few medium roots in cracks and common fine and very fine roots between peds; few fine dendritic tubular pores; common prominent clay films on faces of peds; common fine irregular gypsum crystals and common medium nests of gypsum; 2 percent calcium carbonate equivalent; 10 percent gypsum; 53 percent clay; COLE .098; 1 percent sedimentary gravel; slightly effervescent; moderately alkaline (pH 8.1); clear wavy boundary. (5 to 60 inches thick By horizons)
By2--19 to 36 inches; light yellowish brown (2.5Y 6/4) clay, olive brown (2.5Y 4/3) moist; moderate medium subangular blocky; very hard, extremely firm, very sticky and very plastic; few medium roots in cracks and common fine and very fine roots between peds; few fine dendritic tubular pores; few distinct pressure faces on faces of peds; few fine irregular gypsum crystals and few medium irregular nests of gypsum; 1 percent calcium carbonate equivalent; 10 percent gypsum; 56 percent clay; COLE .126; 1 percent sedimentary gravel; very slightly effervescent; moderately alkaline (pH 8.2); diffuse wavy boundary.
By3--36 to 61 inches; light yellowish brown (2.5Y 6/4) silty clay, olive brown (2.5Y 4/3) moist; moderate medium subangular blocky; very hard, extremely firm, very sticky and very plastic; few very fine roots between peds; few distinct pressure faces on faces of peds; common medium irregular nests of gypsum; 1 percent calcium carbonate equivalent; 4 percent gypsum; 3 percent sedimentary gravel; slightly effervescent; moderately alkaline (pH 8.0); gradual wavy boundary.
Cr--61 to 68 inches; soft Mancos Shale.
TYPE LOCATION: Montezuma County, Colorado; about 20 miles southwest of Towaoc, Colorado; Sentinel Peak Southwest, Colorado USGS quad; lat. 37 degrees 06 minutes 42 seconds N. and long. 108 degrees 58 minutes 13 seconds W., NAD 27.
RANGE IN CHARACTERISTICS:
Soil moisture regime: Typic aridic
Mean annual soil temperature: 54 to 58 degrees F
Depth to paralithic contact: 60 inches or more
Depth to gypsum accumulations: 2 to 10 inches
Depth to gypsic horizon: 3 to 7 inches
Expansive features: cracks to 20 inches, .75 inch wide, 3 or 4 inches apart
Particle-size control section (weighted average):
Clay content: 40 to 60 percent
Rock fragments: 0 to 5 percent sedimentary gravel
A horizon:
Hue: 2.5Y, 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 or 4, dry or moist
Texture: silty clay, clay
Clay content: 40 to 60 percent
Rock fragments: 0 to 5 percent sedimentary gravel
Calcium carbonate equivalent: 1 to 15 percent
EC (dS/m): 0 to 8
Reaction: moderately alkaline
By horizon:
Hue: 2.5Y
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 or 4, dry or moist
Texture: silty clay, clay
Clay content: 40 to 60 percent
Rock fragments: 0 to 5 percent sedimentary gravel
Gypsum: 5 to 15 percent
EC (dS/m): 4 to 8
Calcium carbonate equivalent: 1 to 15 percent
Reaction: moderately alkaline
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Cowboy soils are on fan piedmonts, drainageways, and flood plains. Slopes range from 1 to 12 percent. These soils formed on slope alluvium, alluvium, and residuum derived from Mancos Shale. Elevation ranges from 4,800 to 5,700 feet. The mean annual precipitation is 7 to 10 inches with a uniform precipitation pattern with a slight decrease in May and June, and slight increase in July and August. The mean annual air temperature is 52 to 56 degrees F. The frost-free period is 135 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kava and Oagamati series. The Kava soils are shallow to Mancos Shale and are on knobs and alluvial fans. The Oagamati soils are sodic and are on pediments.
DRAINAGE AND PERMEABILITY: Well drained, high or very high runoff, slow permeability.
USE AND VEGETATION: Cowboy soils are used for grazing. Native vegetation is bottlebrush squirreltail, Gardner saltbush, and little barley.
DISTRIBUTION AND EXTENT: Southwest Colorado; MLRA 35. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona.
SERIES ESTABLISHED: Montezuma County, Colorado, Ute Mountain Area, Colorado and New Mexico, 2005
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Series control section: The zone from 0 to 61 inches.
Particle-size control section: The zone from 10 to 40 inches. (By1, By2, By3 horizons)
Ochric epipedon - the zone from 0 to 5 inches. (A and BA horizons)
Gypsic horizon - the zone from 5 to 36 inches. (By1 and By2 horizons)
Paralithic contact - the contact with Mancos shale at 61 inches. (Cr horizon)
Expansive features - the presence of prismatic structure and significant cracks to the surface at 0 to 20 inches. (A, BA, By horizons)
Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Tenth Edition, 2006
ADDITIONAL DATA: The typical pedon for Cowboy was sampled by NSSL for full characterization, sample S99CO-083-05 and S99CO-083-08