LOCATION OMIO NDEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Typic Haplustolls
TYPICAL PEDON: Omio silt loam - on a 7 percent south-facing slope in a cultivated field. When described the soil was moist throughout. (Colors are for dry soil unless otherwise indicated.)
Ap--0 to 5 inches; dark grayish brown (10YR 4/2) silt loam; very dark brown (10YR 2/2) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine roots; neutral; abrupt smooth boundary. (5 to 7 inches thick)
Bw--5 to 12 inches; dark grayish brown (10YR 4/2) silt loam; very dark grayish brown (10YR 3/2) moist; weak medium prismatic structure parting to moderate medium and coarse subangular blocky; slightly hard, friable, slightly sticky, slightly plastic; many very fine roots; few very fine continuous random pores; mildly alkaline; clear smooth boundary. (5 to 19 inches thick)
BCk--12 to 22 inches; brown (10YR 5/3) silt loam; olive brown (2.5Y 4/4) moist; weak coarse prismatic structure parting to moderate coarse subangular blocky; hard, friable, slightly sticky, slightly plastic; few very fine roots; few very fine continuous random pores; strong effervescence; mildly alkaline; clear smooth boundary. (0 to 16 inches thick)
C1--22 to 31 inches; light yellowish brown (2.5Y 6/4) silt loam; dark grayish brown (2.5Y 4/2) moist; moderate coarse subangular blocky structure; hard, friable, slightly sticky, slightly plastic; few very fine roots; few very fine continuous random pores; strong effervescence; mildly alkaline; abrupt wavy boundary. (0 to 12 inches thick)
2C2--31 to 38 inches; olive (5Y 5/3) silt loam; olive (5Y 4/3) moist; strong medium and coarse angular blocky structure; very hard, firm, slightly sticky, slightly plastic; few very fine roots follow interfaces between adjacent peds; few very fine discontinuous pores; strong effervescence; mildly alkaline; abrupt wavy boundary. (4 to 15 inches thick)
2Cr--38 to 60 inches; light olive gray (5Y 6/2) stratified soft siltstone; slight effervescence.
TYPE LOCATION: Emmons County, North Dakota; 13 miles west and 1.5 miles north of Linton; 1,550 feet south and 900 feet west of the northeast corner, sec. 32, T. 133 N., R. 78 W.
RANGE IN CHARACTERISTICS: The depth to carbonates ranges from 12 to 26 inches. The depth to soft bedrock ranges from 20 to 40 inches. The mollic epipedon ranges from 7 to 16 inches thick and includes all or part of the Bw horizon in most pedons.
The A horizon has hue of 10YR, values of 3 or 4 and 2 or 3 moist, and chroma of 2.
The Bw horizon has hue of 10YR, values of 3 to 5 and 3 or 4 moist, and chroma of 2 to 4 or 2 or 3 moist. It is silt loam and averages 20 to 25 percent clay.
The C horizon has hue of 10YR, 2.5Y or 5Y, values of 5 to 7 and 4 to 5 moist, and chroma of 2 to 4. It is silt loam, loam, or fine sandy loam. The underlying beds are soft to slightly hard siltstone, sandstone or silty shale.
COMPETING SERIES: These are Amsterdam, Bryant, Golva, Peritsa, Sen and Temvik series in the same family and the Chama series. Amsterdam soils contain substantial amounts of volcanic glass shards and are in intermountain valleys. Bryant, Golva, and Temvik soils do not have siltstone, shale or sandstone within depths of 40 inches. Peritsa and Sen soils are formed in place from shale siltstone and do not have the loess mantle. Chama soils have carbonates at depths less than 10 inches.
GEOGRAPHIC SETTING: Omio soils are on hilltops and sideslopes on plane and convex positions. Slope gradients range from 0 to 9 percent. The soils formed in calcareous loess overlying soft siltstone, sandstone or shale. Mean annual temperature ranges from 40 to 45 degrees F, and mean annual precipitation ranges from 15 to 18 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Bryant and Temvik soils and the Amor, Grassna, Reeder and Vebar soils. Amor, Reeder and Vebar soils are on nearby landscapes where the bedrock contains more sand and the loess mantle is absent. Grassna soils are on concave landscape positions and do not have the soft siltstone, shale or sandstone bedrock within 40 inches of the surface.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is slow to medium. Permeability is moderate above the 2C horizon and moderately slow in the 2C horizon and below.
USE AND VEGETATION: The majority of areas of Omio soils are cultivated. The principal crops are wheat, flax, barley, and oats. The native vegetation is western wheatgrass, blue grama, needleandthread, and green needlegrass.
DISTRIBUTION AND EXTENT: South-central North Dakota. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Emmons County, North Dakota, 1979.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 12 inches (Ap and Bw horizons).