LOCATION IRRAWADDY COEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, carbonatic Ustic Calcicryolls
TYPICAL PEDON: Irrawaddy very stony loam, rangeland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 5 inches; very dark grayish brown (10YR 3/2) very stony loam, very dark brown (10YR 2/2) moist; weak fine granular structure; slightly hard, very friable, nonsticky, and nonplastic; many roots; slightly effervescent; 15 percent calcium carbonate equivalent; 40 percent dolomitic stones; moderately alkaline; clear smooth boundary. (4 to 6 inches thick)
B--5 to 14 inches; dark grayish brown (10YR 4/2) very channery loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; slightly hard, very friable, nonsticky, and nonplastic; many roots; slightly effervescent; 13 percent calcium carbonate equivalent; 35 percent dolomitic channery fragments; moderately alkaline; clear smooth boundary. (6 to 9 inches thick)
Ck1--14 to 26 inches; pale brown (10YR 6/3) very channery loam, brown (10YR 5/3) moist; weak medium subangular blocky structure; hard, friable, slightly sticky, and slightly plastic; common roots; calcium carbonate in seams and streaks; strongly effervescent; 51 percent calcium carbonte equivalent; 45 percent dolomitic channery fragments; moderately alkaline; clear smooth boundary. (8 to 14 inches thick)
Ck2--26 to 34 inches; very pale brown (10YR 7/3) very channery loam, pale brown (10YR 6/3) moist; massive; hard, friable, slightly sticky and slightly plastic; few fine roots; calcium carbonate in seams and streaks; violently effervescent; 42 percent calcium carbonate equivalent; 40 percent dolomitic channery fragments and 10 percent dolomitic stone; moderately alkaline; clear smooth boundary. (8 to 10 inches thick)
R--34 inches; hard dolomitic limestone.
TYPE LOCATION: Garfield County, Colorado; about 4.5 miles due west of the village of Dotsero along Coffee Pot Road; 750 feet east and 200 feet north of the southwest corner of section 34, T. 4 S., R. 87 W; Broken rib Creek USGS quad; lat. 39 degrees 39 minutes 05 seconds N. and long. 107 degrees 08 minutes 27 seconds W., NAD 27.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 38 to 46 degrees F. Mean summer soil temperature ranges from 52 to 58 degrees F. The moisture control section is moist, in most years, in some or all parts for 90 or more consecutive days when the soil temperature at 20 inches is greater than 41 degrees F. The soil is at or above 41 degrees F. for 75 to 100 consecutive days. Thickness of the mollic epipedon ranges from 10 to 15 inches. Rock fragments range from 35 to 75 percent. Depth to the lithic contact ranges from 20 to 40 inches. The particle size control section has 12 to 25 percent clay, 28 to 45 percent silt, and 30 to 52 percent sand with 15 to 35 percent coarser than very fine sand.Reaction is mildy alkaline or moderately alkaline.
The A horizon has hue of 2.5Y through 7.5YR, value of 3 through 5, 2 or 3 moist, and chroma of 2 or 3.
A cambic horizon is in some pedons and has weak or moderate subangular blocky structure.
The C horizon has hue of 2.5Y through 7.5YR, value of 6 or 7, 5 or 6 moist, and chroma of 2 or 3.
COMPETING SERIES: This is the Bartine and the closely related Parachute in a different family and the Skaggs series in another subgroup. Bartine soils have silica accumulation above the hard bedrock and a calcic horizon. Parachute series have mixed mineralogy. Skaggs soils have a calcic horizon and a paralithic contact between a depth of 20 to 40 inches.
GEOGRAPHIC SETTING: Irrawaddy soils are on upland ridges and mountainsides. Slopes are 5 to 65 percent. The soils formed in material weathered from limestone. The mean annual temperature ranges from 36 degrees to 44 degrees F and mean annual precipitation is 16 to 22 inches with about equal amounts received throughout the year. Elevation ranges from 8,200 to 8,600 feet. The frost free season is about 60 to 75 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Uracca, Mergel, Jerry, Libeg, Leavittville, Cushool, and Rentsac soils. Uracca, Mergel, Cushool, and Rentsac soils have frigid soil temperatures. Jerry and Libeg soils have an argillic horizon. Leavittville soils have a pachic mollic epipedon.
DRAINAGE AND PERMEABILITY: Well drained; moderate runoff; moderate permeability.
USE AND VEGETATION: Irrawaddy soils are used for grazing. Native vegetation includes Gambel oak, elk sedge, big sagebrush, bluegrass, snowberry and Oregon grape with a few scattered pinyon at lower elevations.
DISTRIBUTION AND EXTENT: Western Colorado. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Garfield County, Colorado, 1982, Aspen Gypsum Soil Survey Area.