LOCATION YAMO COEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Ustic Haplocambids
TYPICAL PEDON: Yamo loam - rangeland. (Colors are for dry soil unless otherwise noted).
A--0 to 8 inches; light brownish gray (10YR 6/2) loam, grayish brown (10YR 5/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; strongly effervescent; moderately alkaline; clear smooth boundary. (6 to 10 inches thick)
Bw--8 to 14 inches; light brownish gray (10YR 6/2) loam, grayish brown (10YR 5/2) moist; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; 10 percent cobbles; strongly effervescent; moderately alkaline; gradual smooth boundary. (4 to 18 inches thick)
Bk1--14 to 20 inches; light brownish gray (10YR 6/2) loam, grayish brown (10YR 5/2) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; 14 percent cobbles; calcium carbonate in few fine seams; violently effervescent; moderately alkaline; clear smooth boundary. (4 to 8 inches thick)
Bk2--20 to 60 inches; light gray (10YR 7/2) loam, grayish brown (10YR 5/2) moist; weak fine subangular blocky structure; hard, friable, sticky and slightly plastic; 10 percent cobbles; few soft nodules of secondary calcium carbonate; violently effervescent; moderately alkaline.
TYPE LOCATION: About 1.5 miles southwest of Eagle, Colorado, in Eagle County; 300 feet north of the center of Sec. 6, T. 5 S., R. 84 W; Eagle USGS quad; lat. 39 degrees 38 minutes 47 seconds N. and long. 106 degrees 51 minutes 09 seconds W., NAD 27.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 42 to 46 degrees F., and mean summer soil temperature ranges from 61 to 68 degrees F., with an average of about 63 degrees F. Depth to the base of the cambic horizon ranges from 14 to 28 inches. Coarse fragments are mainly cobbles but includes pebbles and ranges from 0 to 15 percent. Depth to consistent, continuous k horizons ranges from 10 to 28 inches. Clay in the particle-size control section ranges from 15 to 30 percent. The moisture control section is usually dry in most parts for 15 consecutive days from May 15 through June when the soil temperature is greater than 41 degrees F and moist in some parts for 30 cumulative days in August through October when the soil temperature is greater than 41 degrees F.
The A horizon has hue of 7.5YR through 2.5Y, value of 5 through 7, 4 through 6 moist, and chroma of 2 or 3. Reaction is neutral through moderately alkaline.
The Bw horizon has hue of 7.5YR through 2.5Y, value of 6 or 7, 4 through 6 moist, and chroma of 2 through 4. Reaction is mildly alkaline or moderately alkaline. Texture is loam, sandy clay loam, or clay loam.
The Bk and C horizons have hues of 7.5YR through 2.5Y, value of 6 or 7, 4 through 6 moist and chroma of 2 through 4. Texture is loam, sandy clay loam, or clay loam.
COMPETING SERIES: These are the (T) Chaperton (WY), (T) Cooers (MT), Delpoint (MT), Piceance (CO), (T) Rickman (WY), (T) Spinekop (MT), Trudau (MT), and Yamac (MT) series. Chaperton, Delpoint, Rickman, and Piceance soils have bedrock at depths of 20 to 40 inches below the surface. Cooers soils are moist in some part of the moisture control section for more than 15 consecutive days from May 15 through June. Spinekop soils have lithologic discontinuity below a depth of 18 inches. Trudau soils are saline with a kz horizon. Yamac soils have a moisture control section that is moist in some parts more than 60 percent of the time during the months of May through July when the soil temperature is greater than 41 degrees F. It is usually dry for 30 cumulative days in August through October when the soil temperature is above 41 degrees F. and dry for 60 to 100 days when the soil temperature is below 41 degrees F.
GEOGRAPHIC SETTING: Yamo soils are on fans, side slopes, benches, and toe slopes. Slopes range from 1 to 30 percent. Yamo soils formed in colluvium, alluvium, residuum, and loess derived from mixed sources. The mean annual precipitation is 10 to 15 inches. Mean annual temperature is 40 to 45 degrees F., and mean summer temperature is 60 to 66 degrees F. Elevation is 6,200 to 7,500 feet. The frost-free period is 75 to 105 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Forelle and Mussel soils. Forelle soils have an argillic horizon and the Mussel soils lack a cambic horizon.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability.
USE AND VEGETATION: These soils are used as rangeland, irrigated hayland, cropland, and for homesite development. Principal native vegetation consists of western wheatgrass, bluebunch wheatgrass, Indian ricegrass, prairie junegrass, Wyoming big sagebrush, and Douglas rabbitbrush.
DISTRIBUTION AND EXTENT: Northwestern and western Colorado and possibly adjacent parts of Wyoming and Utah. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Eagle County (Aspen-Gypsum Soil Survey Area), Colorado, 1982.
REMARKS: Diagnostic features include a cambic horizon at 8 to 14 inches. Last updated by the state 12/90.