LOCATION ONTKO OREstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Aquandic Cryaquolls
TYPICAL PEDON: Ontko clay loam--irrigated meadow on a 0.5% slope at an elevation of 4290 feet. (Colors are for moist soil unless otherwise noted. When described on September 20, 2005 the soil was dry above a depth of 30 inches and very slightly moist below that)
Oe--0 to 2 inches; moderately decomposed plant material; 60 percent unrubbed fiber, 30 percent rubbed; abrupt smooth boundary. (1 to 4 inches thick)
A1--2 to 7 inches; black (2.5Y 2.5/1) moist, clay loam; gray (2.5Y 5/1) dry; strong very coarse prismatic structure; extremely firm, very hard, moderately sticky, moderately plastic; common very fine, fine and medium roots; few very fine irregular pores; 5 percent (common) medium prominent irregular dark yellowish brown (10YR 4/6) iron-manganese masses in matrix; 1 percent weakly cemented pumice fine paragravel; slightly acid (pH 6.2); 4 per square meter, 30 cm deep cracks; clear wavy boundary. (5 to 20 inches thick)
A2--7 to 18 inches; black (10YR 2/1) moist, ashy sandy clay loam; gray (2.5Y 5/1) dry; strong very coarse prismatic structure; firm, hard, moderately sticky, moderately plastic; common very fine and fine roots and few medium roots; common very fine and fine irregular and common very fine tubular pores; 2 percent (common) medium prominent irregular dark yellowish brown (10YR 4/6) iron-manganese masses in matrix; 1 percent indurated fine and medium gravel and 5 percent weakly cemented pumice fine paragravel; neutral (pH 6.6); 4 per square meter, 30 cm deep cracks; gradual wavy boundary. (0 to 15 inches thick)
Bg1--18 to 23 inches; dark grayish brown (10YR 4/2) moist, ashy sandy clay loam; light gray (10YR 7/2) dry; strong very thick platy structure; firm, hard, moderately sticky, slightly plastic; common very fine roots, common fine and medium roots; common very fine and fine irregular pores; 1 percent (few) medium faint irregular dark gray (10YR 4/1) iron depletions in matrix and 1 percent (few) medium prominent irregular strong brown (7.5YR 5/8) iron-manganese masses in matrix; 5 percent indurated andesite fine gravel; neutral (pH 6.8); gradual wavy boundary. (0 to 30 inches thick)
Bg2--23 to 29 inches; brown (7.5YR 4/2) moist, clay loam; light gray (10YR 7/2) dry; moderate very thick platy structure; very firm, very hard, moderately sticky, moderately plastic; few very fine, medium roots and coarse roots; common very fine and fine and few medium irregular pores; 10 percent (common) medium faint dark gray (10YR 4/1) iron depletions in matrix, 2 percent (common) fine and coarse prominent reddish yellow (7.5YR 7/8) iron-manganese masses in matrix; 5 percent indurated andesite fine and medium gravel; neutral (pH 7.0); gradual wavy boundary. (0 to 30 inches thick)
Bg3--29 to 42 inches; dark grayish brown (10YR 4/2) moist, gravelly sandy loam; light brownish gray (10YR 6/2) dry; weak coarse angular blocky structure; firm, very hard, slightly sticky, slightly plastic; few very fine and fine roots; many very fine irregular and few fine and medium tubular pores; 2 percent (common) medium faint irregular dark gray (10YR 4/1) iron depletions in matrix, 10 percent (common) coarse and medium prominent irregular strong brown (7.5YR 4/6) iron-manganese masses in matrix; 25 percent indurated andesite fine and medium gravel; neutral (pH 7.0); gradual wavy boundary. (0 to 30 inches thick)
Bw--42 to 54 inches; brown (10YR 4/3) moist, ashy fine sandy loam; light yellowish brown (2.5Y 6/3) dry; weak medium subangular blocky structure; friable, very hard, nonsticky, nonplastic; many very fine irregular and many fine irregular pores; 5 percent weakly cemented pumice fine paragravel and 8 percent indurated andesite fine and medium gravel; neutral (pH 7.0); abrupt wavy boundary. (0 to 30 inches thick)
2C--54 to 60 inches; very dark grayish brown (2.5Y 3/2) moist, very gravelly coarse sand; brown (10YR 5/3) dry; single grain; loose, nonsticky, nonplastic; many fine irregular pores; 5 percent weakly cemented pumice fine paragravel and 50 percent indurated andesite fine and medium gravel; neutral (pH 6.9).
TYPE LOCATION: Klamath County, Oregon; about 3.2 miles northwest of the town of Sprague River; 1,700 feet west and 650 feet north of the southeast corner of Section 32, T. 35 S., R. 10 E., Sprague River West, Oregon USGS quadrangle; UTM: 619024.34E, 4705030.1N, Datum NAD83, Zone 10; lat. 4229'18.51 degrees north, and long. 12133'6.13 degrees west.
RANGE IN CHARACTERISTICS:
Soil moisture - The soils are saturated throughout in the spring; moisture control section (4 to 12 inches) saturated in all parts for 30 to 60 days between March thru May, dry in all parts for 45 to 90 or more days between July thru October.
Soil temperature - cryic regime
Mean annual soil temperature - 37 to 43 degrees F.
Mean summer soil temperature - 40 to 43 degrees F.
Mean winter soil temperature - 34 to 40 degrees F
Particle-size control section: from 10 to 40 inches below the mineral soil surface
Clay content, average: 20 to 30 percent
Rock fragment content, average: 0 to 15 percent
Pararock fragment content, average: 2 to 5 percent
Diagnostic horizons and features:
Mollic epipedon thickness - 10 to 25 inches.
Depth to ashy-modified soil textures having aquandic subgroup properties - 5 to 20 inches from the mineral soil surface. The horizons and layers having ashy textural modifiers have 5 to 15 percent glass and the ammonium oxalate (Al+ Fe) is 0.3 to 0.7
A horizons
Value: 2 through 3 moist.
Chroma: 0 or 1, moist or dry.
Texture: Upper part is silty clay loam or clay loam, lower part is ashy sandy clay loam.
Clay content: 27 to 35 percent.
Pararock fragment content: 0 to 10 percent fine pumice paragravel.
Rock fragment content: 0 to 2 percent fine gravel.
Bg horizons
Value: 4 or 5 moist, 6 through 8 dry.
Chroma: 1 through 3 moist, 1 or 2 dry.
Texture: Upper part is ashy sandy clay loam and the lower part is silty clay loam, clay loam, sandy clay loam or gravelly sandy loam.
Clay content: 10 to 35 percent.
Pararock fragment content: 0 to 10 percent fine pumice paragravel.
Rock fragment content: 0 to 25 percent fine and medium gravel.
Bw horizon
Value: 2 through 4 moist, 4 through 6 dry.
Chroma: 2 or 3 moist or dry.
Texture: Clay loam, silty clay loam, sandy clay loam, ashy sandy clay loam, ashy fine sandy loam, gravelly sandy loam.
Pararock fragment content: 0 to 10 percent fine pumice paragravel.
Rock fragment content: 0 to 25 percent fine and medium gravel.
2C horizon (where present)
Value: 2 through 4 moist, 3 through 5 dry.
Chroma: 2 or 3 moist or dry.
Texture: ashy fine sandy loam, gravelly sandy loam, very gravelly coarse sand.
Clay content: 2 to 20 percent.
Pararock fragment content: 0 to 10 percent fine pumice paragravel.
Rock fragment content: 0 to 50 percent fine and medium gravel.
COMPETING SERIES:
Gerow (tentative OR) - aquandic subgroup properties extend to the surface; mollic epipedon is greater than 60 inches thick; the difference between mean summer and mean winter temperatures is more than 10.8 F.
Lavaspring (CA) - mollic epipedon is 30 to 60 inches thick; soils are stratified in the particle-size control section and average 15 to 35 percent rock fragments in the particle-size control section.
Spragueriver (tentative OR) - mollic epipedon is greater than 40 inches thick
GEOGRAPHIC SETTING: Ontko soils are on flood plains and in basins. The soils formed in alluvium derived mainly from tuff, diatomite, and volcanic ash. Slopes are 0 to 1 percent. Elevations range from 4,100 to 4,400 feet. The climate is characterized by cold moist winters and cool dry summers. The mean annual precipitation is 14 to 20 inches. The mean winter (December-February) air temperature is about 30 degrees F., the mean summer (June-August) air temperature is about 61 degrees F., and the mean annual air temperature is 42 to 48 degrees F. The frost-free period is 40 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dilman, Klamath and Yonna soils. Dilman soils are on a slightly higher flood plain position adjacent to Ontko soils. Klamath soils are on a slightly lower flood plain position than Ontko soils, are fine-silty and lack the aquandic properties. Yonna soils are on a higher flood plain position than Ontko, are somewhat poorly drained and are loamy over ashy or ashy-pumiceous, aniso.
DRAINAGE AND PERMEABILITY: Poorly or very poorly drained; moderately slow permeability in the upper part over moderately rapid through the Bw horizon, over very rapid in the 2C horizon. Endosaturation is present with an apparent seasonal high water table between the soil surface and 1 foot from March to May. Flooding occurs in some areas from March to May.
USE AND VEGETATION: Ontko soils are used for native meadow hay and pasture, irrigated pasture and hay, and wildlife habitat. The vegetation is meadow plants that are dominantly tufted hairgrass, redtop, meadow barley, rush, sedge, and Kentucky bluegrass.
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: Prineville Area, Oregon, 1966.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from 2 to 18 inches.
Cambic horizon - The zone from 18 to 54 inches.
Aquandic soil properties - The zone from 7 to 23 inches.
Aquic conditions - The conditions of endosaturation and reduction between the soil surface and 42 inches. Common prominent redox concentrations from 7 to 18 inches (lower part of the mollic epipedon)
Particle-size control section - The zone from 2 to 42 inches.