LOCATION OSMUND WY+IDEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Pachic Haplocryolls
TYPICAL PEDON: Osmund gravelly loam - grassland (Colors are for dry soil unless otherwise noted)
A1--0 to 10 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; strong fine crumb and granular structure; soft, very friable; 10 percent gravel and cobble; neutral (pH 6.8); clear smooth boundary. (6 to 12 inches thick)
B21--10 to 20 inches; brown (7.5YR 4/3) gravelly loam, dark brown (7.5YR 3/3) moist; moderate medium and fine subangular blocky structure that parts to moderate medium granules; slightly hard, very friable; 15 percent gravel and cobble; few thin glossy patches on faces of peds; weak glossy patches in root channels; neutral (pH 6.8); gradual smooth boundary. (6 to 14 inches thick)
B22--20 to 30 inches; brown (7.5YR 5/3) gravelly loam, brown (7.5YR 4/3) moist; moderate medium subangular blocky structure that parts to moderate coarse granules; hard, very friable; few thin glossy patches on faces of peds; 25 percent gravel and cobble; neutral (pH 6.8); clear wavy boundary. (8 to 14 inches thick)
Cca--30to 60 inches; brown (7.5YR 5/3) very gravelly loam, brown (7.5YR 4/3) moist; massive; slightly hard, very friable; 55 percent gravel and cobble; visible secondary carbonate as concretions and as coatings on rock fragments; calcareous; moderately alkaline (pH 8.0).
TYPE LOCATION: Lincoln County, Wyoming; approximately 400 feet north of the southwest corner of Sec. 7, T. 31N., R. 118W.
RANGE IN CHARACTERISTICS: In some pedons a distinct cambic horizon may be absent but in these areas the mollic epipedon is noncalcareous in at least the upper part, and has brighter chroma, redder hue, moderate structure of evidence of carbonate removal in the lower part, and is underlain by a continuous horizon of visible carbonate accumulation. The mollic epipedon is 16 to 40 inches thick, depth to calcareous material ranges from 10 to 40 inches, the solum is 16 to 40 inches thick. The content of organic carbon in the mollic epipedon ranges from .8 to 3 percent and decreases uniformly with depth. The matrix material within the control section is typically loam or clay loam with 18 to 35 percent clay, 20 to 55 percent silt, and 20 to 50 percent sand, with more than 15 percent fine sand or coarser including coarse fragments, and with less than 35 percent in the upper part of the control section, and from 35 to 80 percent in the lower part. Mean annual soil temperature ranges from 32 to 46 degrees F., and mean summer soil temperature ranges from 40 to 58 degrees F. The A1 horizon has hue of 2.5Y through 7.5YR, value of 4 or 5 dry and 2 or 3 moist and chroma of 1 through 3. It usually has fine granular or crumb primary structure but has subangular blocky structure in some pedons. This horizon is soft to slightly hard and neutral to mildly alkaline. The B2 horizon has hue of 2.5Y through 7.5YR, value of 5 or 6 dry and 4 or 5 moist and chroma of 2 through 4. It has typically subangular blocky primary structure but has weak prismatic structure in some pedons. This horizon is neutral to slightly acid. The C horizon has hue of 2.5Y through 7.5YR. It contains about 3 to 14 percent calcium carbonate. This horizon is gravelly or very gravelly loam or clay loam. It is mildly alkaline to strongly alkaline.
COMPETING SERIES: These are the Adel, Bullrey, Gallatin, Idmon, Karlan, Kennally, Lamphier, Leavittville, Mundos, Nutrioso, Pavohroo and Reca series. Adel, Bullrey, Idmon, Kennally, Lamphier, Nutrioso and Reca soils are noncalcareous throughout. Gallatin soils lack a loamy-skeletal substratum above 40 inches. Karlan soils have a lithic contact between 20 and 40 inches. Leavittville soils have a gravel-free upper control section at least 20 inches thick and have less than 15 percent fine sand or coarser including coarse fragments in the control section. Mundos soils have lithochromic hue of 5YR or redder. Pavohroo soils lack a loamy-skeletal substratum above 40 inches and are noncalcareous.
GEOGRAPHIC SETTING: Osmund soils are on gently to moderately sloping alluvial fans and valley filling sideslopes. Slopes usually range from 0 to about 10 percent. These soils formed in calcareous, alluvial fan sediments derived from a variety of crystalline rock. At the type location the average annual precipitation is 18 inches with nearly equal amounts of precipitation occurring during most months. The mean annual temperature is 39 degrees F., the mean summer temperature is 58 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Grayback and Thayne soils. Grayback soils have very gravelly loamy sand or sand strata above 40 inches. Thayne soils have mollic epipedons less than 16 inches thick.
DRAINAGE AND PERMEABILITY: Well-drained; medium runoff; moderate permeability.
USE AND VEGETATION: These soils are used as dry and irrigated cropland and as native pastureland. Common crops are small grains and hay. Principal native plants are bluegrass, timothy, and sagebrush.
DISTRIBUTION AND EXTENT: Mountainous areas of Wyoming, Colorado, and Idaho. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Lincoln County (Star Valley Conservation District), Wyoming, 1945.
REMARKS:
On 3/4/2009 this description is being entered for the first time into the OSD files. Although it was established in 1945 it has never been in an electronic form. Except for the classification, this series has not been reviewed or updated.