LOCATION DILMAN OREstablished Series
TAXONOMIC CLASS: Loamy over ashy or ashy-pumiceous, mixed over glassy, superactive Aquandic Cryaquolls
TYPICAL PEDON: Dilman silty clay loam--pasture. (Colors are for moist soil unless otherwise noted.)
A1--0 to 3 inches; black (10YR 2/1) silty clay loam, dark gray (10YR 4/1) dry; weak thin platy structure parting to moderate very fine granular; slightly hard, firm, very sticky and moderately plastic; many very fine roots; common very fine tubular pores; neutral (pH 6.6); abrupt wavy boundary. (3 to 10 inches thick)
A2--3 to 13 inches; black (N 2/0) clay, dark gray (N 4/0) dry; moderate medium prismatic structure; hard, very firm, very sticky and very plastic; many very fine roots; common very fine tubular pores; many pressure cutans on faces of peds; neutral (pH 6.8); clear wavy boundary. (0 to 10 inches thick)
Bw1--13 to 21 inches; very dark gray (10YR 3/1) clay loam, gray (2.5Y 5/1) broken and dry, gray (2.5Y 6/1) rubbed and dry; weak medium prismatic structure parting to weak medium angular blocky; very hard, firm, moderately sticky and moderately plastic; common very fine roots; many very fine tubular pores; many pressure cutans on faces of peds; common fine distinct light olive brown (2.5Y 5/4) dry, masses of iron accumulation; neutral (pH 7.0); gradual wavy boundary. (0 to 12 inches thick)
2Bw2--21 to 28 inches; very dark gray (10YR 3/1) ashy sandy clay loam, gray (10YR 6/1) dry; many fine black coatings on peds; weak medium angular blocky structure; very hard, firm, moderately sticky and moderately plastic; common very fine roots; many very fine tubular pores; many fine prominent light olive brown (2.5Y 5/4) dry, masses of iron accumulation; about 50 percent pumiceous ash grains; slightly alkaline (pH 7.4); gradual wavy boundary. (0 to 11 inches thick)
2Bw3--28 to 37 inches; very dark grayish brown (10YR 3/2) ashy sandy clay loam, light gray (10YR 7/2) dry; massive; slightly hard, friable, moderately sticky and slightly plastic; common very fine roots; many very fine tubular pores; many fine and medium distinct dark brown (7.5YR 3/4) masses of iron and manganese accumulation; about 60 percent pumiceous ash grains; slightly alkaline (pH 7.6); clear wavy boundary. (0 to 12 inches thick)
2Bw4--37 to 50 inches; grayish brown (10YR 5/2) and light gray (10YR 7/2) ashy coarse sand, light gray (10YR 7/1) and white (N 8/0) dry; massive; soft, very friable, nonsticky and nonplastic; common very fine roots; many very fine tubular pores; about 80 percent pumiceous ash grains; slightly alkaline (pH 7.6); abrupt smooth boundary. (8 to 20 inches thick)
3Ab--50 to 60 inches; brown (7.5YR 4/3) clay loam, brown (7.5YR 5/3) dry; moderate fine angular blocky structure; very hard, very firm, very sticky and very plastic; common very fine roots; common very fine tubular pores; many reddish gray (5YR 5/2) seams and threads; effervescent in seams and threads; neutral (pH 6.8).
TYPE LOCATION: Klamath County, Oregon; about 2 miles east of the town of Bly; 100 feet east of road and 30 feet north of river channel; 1,750 feet east and 400 feet north of the southwest corner of section 31, T. 36 S., R. 15 E.
RANGE IN CHARACTERISTICS:
Soil moisture - The soils are saturated and have a high water table in the spring and early summer; aquic moisture regime.
Mean annual soil temperature - 44 to 47 degrees F.
Mean summer soil temperature - 56 to 59 degrees F.
Mollic epipedon thickness - 7 to 20 inches.
Depth to the ashy 2Bw horizon 14 to 24 inches.
Depth to the loamy 3A horizon 40 to more than 60 inches.
A horizons - Hue: 10YR or Neutral (N).
Value: 2 or 3 moist, 3 through 5 dry.
Chroma: 0 or 1, moist and dry.
Texture: Silty clay loam but ranges to clay in the lower part.
Bw horizons - Hue: Neutral (N), 10YR, or 2.5Y.
Value: 3 or 4 moist, 5 or 6 dry.
Chroma: 0 or 1, moist or dry.
Texture: silty clay loam, or clay loam.
Clay content: 27 to 35 percent.
2Bw horizons - Hue: Neutral (N), 10YR, or 2.5Y.
Value: 3 through 6 moist, 6 through 8 dry.
Chroma: 1 through 2, moist or dry.
Texture: Ashy sandy clay loam or ashy sandy loam over ashy loamy coarse sand or ashy coarse sand.
Pararock fragments: 0 to 15 percent fine (2 to 5 mm diameter) pumice paragravel.
Volcanic glass content: 50 to 70 percent.
Acid oxalate extractable aluminum plus one-half the iron is 0.2 to 0.5 percent.
Estimated 15-bar moisture content (air-dried): Less than 10 percent.
3A horizon Value 3 or 4 moist, 5 to 7 dry.
Chroma 1 to 3 moist and dry.
Texture clay loam, clay or silty clay loam.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Dilman soils are on flood plains and narrow swales. These soils formed in stratified alluvium derived mainly from tuff, diatomite, and pumiceous volcanic ash. Slopes are 0 to 1 percent. Elevations range from 4,100 to 4,400 feet. The climate is semiarid and characterized by cold, moist winters and cool, dry summers. The mean annual precipitation is 15 to 18 inches. The mean January temperature is about 26 degrees F., mean July temperature is about 59 degrees F., and the mean annual temperature is 42 to 45 degrees F. The frost-free period is 50 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Klamath, Yonna and Ontko soils. Klamath soils are fine-silty, lack the Aquandic zone and are on lower landscape positions. Yonna soils are loamy over ashy or ashy-pumiceous but are also aniso wit loamy material below the ash but above 40 inches. Ontko soils are fine-loamy.
DRAINAGE AND PERMEABILITY: Poorly drained; medium surface runoff; slow permeability in the upper part over rapid permeability in the ashy lower part.
USE AND VEGETATION: Dilman soils are used for native meadow pasture and hay production. Areas that are drained and irrigated grow alfalfa and pasture. The native vegetation is mainly northern mannagrass, Nebraska sedge, Baltic rush, and other wet meadow plants.
DISTRIBUTION AND EXTENT: Pumiceous ash-mantled areas of central and southern Oregon. These soils are moderately extensive. MLRAs 6 and 21.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Deschutes County, Oregon, 1946.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 13 inches.
Cambic horizon - The zone from 13 to 37 inches.
Aquandic soil properties - The zone from 13 to 37 inches (Bw1 and Bw2 horizons).
Aquic conditions - The conditions of endosaturation, reduction, and redoximorphic features between 3 and 50 inches at certain times during normal years.
Particle-size control section - The zone from 10 to 40 inches; 10 to 21 inches loamy and 21 to 40 inches ashy.