LOCATION MIKKALO OR+WAEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, mesic Calcidic Haploxerolls
TYPICAL PEDON: Mikkalo silt loam, grassland. (Colors are for dry soil unless otherwise stated.)
A1--0 to 3 inches; grayish brown (10YR 5/2) silt loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; neutral (pH 6.8); gradual wavy boundary. (3 to 8 inches thick)
A2--3 to 11 inches; grayish brown (10YR 5/2) silt loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; neutral (pH 6.8); gradual wavy boundary. (3 to 8 inches thick)
Bw1--11 to 16 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; slightly alkaline (pH 7.4); gradual wavy boundary. (4 to 9 inches thick)
Bw2--16 to 27 inches; pale brown (10YR 6/3) silt loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; slightly alkaline (pH 7.6); gradual smooth boundary. (4 to 12 inches thick)
Bk1--27 to 35 inches; very pale brown (10YR 7/3) silt loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular pores; 5 percent gravel 2mm - 10mm in diameter; slightly effervescent; slightly alkaline (pH 7.8); abrupt wavy boundary. (6 to 14 inches thick)
Bk2--35 to 38 inches; very pale brown (10YR 8/2) silt loam, brown (10YR 5/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; few very fine tubular pores; 15 percent gravel 2mm - 10mm diameter; strongly effervescent; few streaks and splotches of soft powdery lime; moderately alkaline (pH 8.4); gradual wavy boundary. (2 to 8 inches thick)
2R--38 inches; lime-coated basalt.
TYPE LOCATION: Gilliam County, Oregon; 20 feet north of gravel road in the SE1/4 SE1/4 NE1/4 section 19, T. 1 S., R. 21 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 50 to 53 degrees F. These soils are usually dry in all parts of the soil between depths of 4 and 12 inches. Depth to bedrock ranges from 20 to 40 inches. The mollic epipedon is 7 to 16 inches thick. The control section is silt loam with 8 to 12 percent clay and less than 15 percent coarser than very fine sand. Depth to secondary carbonates is 16 to 30 inches.
The A horizon has value of 4 or 5 dry, 2 or 3 moist and chroma of 2 or 3 dry and moist. It has weak or moderate granular, platy or subangular blocky structure.
The Bw horizon has value of 5 or 6 dry, 3 or 4 moist and chroma of 3 or 4 dry and moist. It has weak or moderate subangular blocky or prismatic structure. Reaction is slightly acid to moderately alkaline.
The Bk horizon has value of 6 thru 8 dry, 4 thru 6 moist and chroma of 2 or 3 dry and moist. It is slightly through strongly alkaline. It has 5 to 15 percent calcium carbonate.
COMPETING SERIES: These are the Ellisforde, Hodad, Neeley and Ritzville series. Ellisforde, Neeley and Ritzville soils are deeper than 40 inches to bedrock. Also, Ellisforde soils have laminated lake-laid silt at depths of 20 to 40 inches. Neeley soils have a calcic horizon at depths of 11 to 20 inches. Hodad soils have a calcic horizon at 7 to 20 inches.
GEOGRAPHIC SETTING: Mikkalo soils are on hills, plateaus, and ridges at elevations of 300 to 2,700 feet. Slopes range from 0 to 60 percent. These soils formed in loess. They have a small amount of volcanic ash in the surface layer. These soils are in a semiarid climate with a mean annual precipitation of 9 to 12 inches with cool moist winters and warm dry summers. Mean January temperature is 29 degrees F., mean July temperature is 71 degrees F., and mean annual temperature is 48 to 53 degrees F. The frost-free season is 115 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Ritzville soils.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate permeability.
USE AND VEGETATION: Used for production of small grains and for rangeland. The native vegetation is bluebunch wheatgrass, green rabbitbrush, big sagebrush, balsamroot and yarrow.
DISTRIBUTION AND EXTENT: Eastern Oregon and Eastern Washington. Series is moderately extensive.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Morrow County, Oregon, 1977.
REMARKS: Diagnostic horizons and features in this pedon include:
Mollic epipedon - from surface to 16 inches (A1, A2, and Bw1 horizons).
Cambic horizon - from 16 to 27 inches (Bw2 horizon).
Secondary carbonates - from 27 to 38 inches (Bk1 and Bk2 horizons).
Aridic soil moisture regime.