LOCATION THREEBUCK OR
Established Series
Rev. SCW/RWL
03/2013
THREEBUCK SERIES
The Threebuck series consists of deep, well drained soils formed in ash over clayey colluvium. Threebuck soils are on north and east-facing side slopes of hills, mountains, and canyons. Slopes are 2 to 90 percent. The mean annual precipitation is about 24 inches and the mean annual temperature is about 43 degrees F.
TAXONOMIC CLASS: Ashy over clayey-skeletal, glassy over smectitic, frigid Alfic Vitrixerands
TYPICAL PEDON: Threebuck ashy loam, woodland, on a 41 percent northwest-facing slope at an elevation of 3,760 feet (Colors are for moist soil unless otherwise noted. When described on March 24, 1992, the soil was moist throughout the soil profile.)
Oi--0 to 1 inch; slightly decomposed twigs, needles, and moss.
A--1 to 5 inches; very dark grayish brown (10YR 3/2) ashy loam, grayish brown (10YR 5/2) dry; moderate fine granular structure; soft, friable, slightly sticky and slightly plastic; few fine and many very fine roots; common fine and many very fine irregular pores; 5 percent gravel; slightly acid (pH 6.2); clear smooth boundary. (3 to 9 inches)
Bw--5 to 15 inches; brown (7.5YR 4/2) cobbly ashy loam, pinkish gray (7.5YR 6/2) dry; moderate medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine and common very fine roots; few fine and many very fine tubular pores; 20 percent cobbles; slightly acid (pH 6.4); abrupt wavy boundary. (5 to 21 inches)
2Bt1--15 to 26 inches; brown (7.5YR 4/3) very stony clay, brown (7.5YR 5/3) dry; strong medium and coarse subangular blocky structure; hard, firm, moderately sticky and very plastic; few fine and very fine roots; few fine and common very fine tubular pores; many distinct clay films on ped faces; 30 percent stones, 15 percent cobbles, and 10 percent gravel; slightly acid (pH 6.5); clear wavy boundary.
2Bt2--26 to 37 inches; brown (7.5YR 4/3) very gravelly clay, brown (7.5YR 5/3) dry; moderate medium and coarse subangular blocky structure; hard, firm, moderately sticky and very plastic; few very fine roots; few very fine tubular pores; many distinct clay films on ped faces; 35 percent gravel and 15 percent cobbles; slightly acid (pH 6.5); clear wavy boundary. (Combined thickness of the 2Bt horizon is 12 to 22 inches.)
3Bt3--37 to 48 inches; dark brown (7.5YR 3/3) gravelly clay, brown (7.5YR 4/3) dry; strong coarse subangular blocky structure; very hard, firm, moderately sticky and very plastic; few very fine roots; few very fine tubular pores; continuous prominent clay films on ped faces and in pores; 10 percent cobbles, 15 percent gravel, and 5 percent paragravel (2 to 5 mm.); neutral (pH 7.0); abrupt wavy boundary. (11 to 20 inches)
4R--48 inches; basalt bedrock
TYPE LOCATION: Wallowa County, Oregon, about 4 miles south of the town of Wallowa; about 2,600 feet west and 2,600 feet south of the northeast corner of section 3, T. 1 S., R. 42 E. (USGS Wallowa, Oregon 7.5 minute Topographic Quadrangle; Latitude 45 degrees, 30 minutes, 30 seconds N. and Longitude 117 degrees, 33 minutes, 04 seconds W.)
RANGE IN CHARACTERISTICS: The soils are usually moist, but are dry in all parts of the moisture control section for 45 to 60 consecutive days during the summer months. The mean annual soil temperature at a depth of 20 inches is 44 to 47 degrees F. The upper 14 to 22 inches has an estimated bulk density less than 0.90 grams per cubic centimeter, phosphate retention of 30 to 50 percent, acid oxalate extractable aluminum plus one-half iron of 0.4 to 1.0 percent, and volcanic glass of 30 to 50 percent. The lower part of the particle-size control section averages 35 to 50 percent clay and 35 to 60 percent rock fragments. Depth to bedrock is 40 to 60 inches. Reaction is moderately acid or slightly acid throughout except for the 3Bt3 horizon which is slightly acid or neutral.
The A horizon has value of 2 to 4 moist, 4 to 6 dry, and chroma of 1 to 3 moist and dry. It is ashy loam with 5 to 15 percent clay. It has 0 to 10 percent gravel and 0 to 5 percent cobbles. It is loam with 10 to 20 percent clay.
The Bw horizon has hue of 10YR or 7.5YR, value of 3 or 4 moist, 6 or 7 dry, and chroma of 2 to 4 moist and dry. It is ashy loam or ashy silt loam with 15 to 25 percent clay, 15 to 25 percent clay, 0 to 20 percent cobbles and 0 to 15 percent gravel.
The 2Bt horizon has hue of 7.5YR or 10YR, value of 3 or 4 moist, 5 or 6 dry, and chroma of 2 to 4 moist and dry. The texture is silty clay loam or clay with 30 to 45 percent clay. It has 0 to 30 percent stones, 15 to 40 percent cobbles, and 10 to 35 percent gravel. Clay films are common or many and faint or distinct.
The 3Bt3 horizon has hue of 5YR or 7.5YR, value of 3 or 4 moist, 4 or 5 dry , and chroma of 3 to 6 moist, 3 or 4 dry. The texture is silty clay loam or clay with 35 to 50 percent clay. It has 0 to 10 percent stones, 10 to 35 percent cobbles, and 15 to 35 percent gravel. Clay films are many or continuous and distinct or prominent.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Threebuck soils are on north and east-facing side slopes of hills, mountains, and canyons. Slopes are 2 to 90 percent. These soils formed in ash over colluvium consisting of clay and basaltic rock fragments. Elevation is 2,800 to 5,400 feet. The climate is characterized by cold wet winters and hot dry summers. The mean annual precipitation is 15 to 30 inches. The mean annual temperature is 42 to 45 degrees F. The frost-free period is 70 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Gwinly,
Harlow,
Klicker,
Linecreek (T),
Mallory,
Snell, and
Tamarackcanyon (T) soils. Gwinly and Mallory soils are clayey-skeletal, mesic and are located on nonforested south-facing side slopes. Harlow and Snell soils are clayey-skeletal, shallow and moderately deep to bedrock, respectively, and are on nonforested south-facing side slopes. Klicker soils are loamy-skeletal and are located on forested south-facing side slopes. Linecreek soils are ashy-skeletal, very deep to bedrock, and are found on very steep, forested north-facing side slopes. Tamarackcanyon soils are moderately deep to bedrock, clayey-skeletal, and are located plateaus and side slopes.
DRAINAGE AND PERMEABILITY: Well drained; moderate over slow permeability.
USE AND VEGETATION: These soils are used for timber production. The principle tree species are Douglas fir, scattered western larch, and scattered white fir. The understory vegetation includes strawberry, currant, and ninebark. In the rangeland - forest transition, ponderosa pine and common snowberry are present on north-facing side slopes.
DISTRIBUTION AND EXTENT: Northeastern Oregon, MLRA 10. This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Wallowa County Area, Oregon, l998. The name is derived from Threebuck Creek located about 10 miles east of Joseph.
REMARKS: Diagnostic horizons and features in this pedon are:
Ochric epipedon - the zone from 1 to 5 inches (A horizon).
Cambic horizon - the zone from 15 to 48 inches (Bw horizon).
Argillic horizon - the zone from 15 to 48 inches (2Bt1, 2Bt2, and 3Bt3 horizons)
Andic properties - from the surface to 15 inches (A and Bw horizons) based on lab data from similar Threebuck soil.
Glassy mineralogy - from 0 to 14 inches with 8(Si)+2(Fe) less than 5, with the weighted average of 32 percent volcanic glass.
Series has been reclassified from medial to ashy.
Particle-size control section - from 1 to 41 inches (A, Bw, 2Bt1, 2Bt2, and the upper part of the 3Bt3 horizon). The upper 0 to 14 inches of the control section is medial based on 15-bar water content (air-dried) is more than 12 percent. The lower 14 to 40 inches is clayey-skeletal based on estimated field textures.
Depth to diagnostic horizons and features are measured from the top of the first mineral layer.
ADDITIONAL DATA: Partial laboratory data is available for this soil. Reference samples are listed as pedon 91Z 209, samples 91Z1221-1225 from Wallowa County, Oregon, NSSL, Lincoln, Neb., 6/92.
National Cooperative Soil Survey
U.S.A.