LOCATION MORROW OR+WAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Calcic Argixerolls
TYPICAL PEDON: Morrow silt loam, cultivated. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 9 inches; very dark brown (10YR 2/2) silt loam, grayish brown (10YR 5/2) dry; weak fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine irregular pores; surface 1/4 to 1/2 inch crusted and vesicular; neutral (pH 6.8); abrupt smooth boundary. (6 to 15 inches thick)
2Bt--9 to 14 inches; dark brown (10YR 3/3) silty clay loam, brown (10YR 5/3) dry; very dark grayish brown (10YR 3/2) coatings on peds; weak fine prismatic structure parting to moderate medium angular blocky; very hard, firm, moderately sticky and moderately plastic; common very fine roots; many very fine tubular pores; many distinct clay films; neutral (pH 7.0); clear smooth boundary. (4 to 16 inches thick)
2Btk--14 to 19 inches; dark brown (10YR 3/3) heavy silt loam, pale brown (10YR 6/3) dry; moderate fine subangular blocky structure; hard, firm, slightly sticky and slightly plastic; few very fine roots; many very fine tubular pores; few faint clay films; common light gray (10YR 7/2) lime seams; strongly effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (0 to 12 inches thick)
2Bk--19 to 26 inches; brown (10YR 4/3) silt loam, light brownish gray (10YR 6/2) dry; massive; hard, friable, slightly sticky and slightly plastic; many very fine tubular pores; violently effervescent seams of light brownish gray (10YR 6/2) soft segregated lime; moderately alkaline (pH 8.3); abrupt wavy boundary. (4 to 10 inches thick)
3R--26 inches; fractured basalt with coatings of carbonates on rock surfaces.
TYPE LOCATION: Morrow County, Oregon; 110 feet west of gravel road in NE1/4 SE1/4 SE1/4 section 17, T. 3 S., R. 26 E.
RANGE IN CHARACTERISTICS: In most years the soil is usually moist but is dry for 60 to 90 consecutive days following the summer solstice between depths of 4 and 12 inches. The mean annual soil temperature is 48 to 52 degrees F. Thickness of the solum and depth to bedrock is 20 to 40 inches. The mollic epipedon is 9 to 20 inches thick. Depth to the calcic horizon is 10 to 31 inches.
The Ap or A horizon has value of 4 or 5 dry, 2 or 3 moist and chroma of 2 or 3 moist or dry.
An AB horizon is present in some pedons with color and texture similar to the A horizon.
The 2Bt horizon has value of 4 to 6 dry, 2 to 4 moist and chroma of 2 to 4 moist and dry. It is heavy silt loam or silty clay loam and has 24 to 35 percent clay and less than 15 percent material coarser than very fine sand. Reaction is neutral to moderately alkaline.
The 2Btk horizon, when present, has value of 5 through 7 dry, 3 through 5 moist, chroma of 2 through 4 moist and dry. It is silt loam or silty clay loam with 18 to 30 percent clay and is strongly to violently effervescent with segregated lime. Reaction is moderately or strongly alkaline.
The 2Bk horizon has value of 6 or 7 dry, 4 or 5 moist and chroma of 2 to 4 moist and dry. It is strongly to violently effervescent. It is silt loam or silty clay loam and has 0 to 10 percent fine gravel. Reaction is moderately or strongly alkaline.
COMPETING SERIES: These are the
Broadax,
McKay,
Nephi,
Parleys, and
Wannacott series.
Broadax soils greater than 40 inches to bedrock or duripan; dry for 75 to 105 consecutive days following the summer solstice
McKay soils greater than 60 inches to bedrock
Nephi soils greater than 60 inches to bedrock (limestone, shale)
Parleys soils greater than 60 inches to bedrock
Wannacott soils 20 to 40 inches to a densic contact (glacial till); dry for 90 to 105 consecutive days following the summer solstice
GEOGRAPHIC SETTING: Morrow soils are on slopes 0 to 40 percent at elevations of 1,800 to 3,500 feet. The soils formed in loess mixed with some old alluvium or residuum derived from basalt. Summers are warm and dry. Winters are cool and moist with a mean winter temperature of 33 to 36 degrees F. The mean annual temperature is 46 to 50 degrees F. Mean annual precipitation is 12 to 16 inches. Frost-free season is 110 to 175 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bakeoven, Lickskillet and Wrentham soils. Bakeoven, Lickskillet and Wrentham soils contain more than 50 percent fragments coarser than 2mm. Bakeoven and Lickskillet soils are less than 20 inches deep to bedrock. These soils are located on plateaus and canyon slopes.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate or moderately slow permeability.
USE AND VEGETATION: Principal use is for production of dryland grain crops. Other uses are hay and pasture and native rangeland. Vegetation is mainly bluebunch wheatgrass, Idaho fescue, Sandberg bluegrass and forbs such as yarrow, phlox and buckwheat.
DISTRIBUTION AND EXTENT: North-central Oregon and central Washington; MLRA 8. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Gilliam County, Oregon, 1939.
REMARKS: Diagnostic horizons and features in this pedon include:
Mollic epipedon - from the surface to 14 inches (Ap and 2Bt horizons).
Argillic horizon - from 9 to 19 inches (2Bt and 2Btk horizons).
Calcic horizon - from 14 to 26 inches (2Btk and 2Bk horizons); assume to have over 15 percent equivalent. The amount of calcium carbonate equivalent needs to be determined to verify if this series has over 15 percent calcium carbonate, or if it only has identifiable secondary carbonates.