LOCATION MINAM OR

Established Series
Rev. WEL/RWL
03/2013

MINAM SERIES

The Minam series consists of very deep, well drained soils that formed in mixed alluvium and colluvium with an influence of volcanic ash and loess. Minam soils are on alluvial or pediment fans. Slopes are 0 to 15 percent. The mean annual precipitation is about 22 inches and the mean annual temperature is about 43 degrees F.

TAXONOMIC CLASS: Fine-loamy, isotic, frigid Vitrandic Haploxerolls

TYPICAL PEDON: Minam ashy loam - cultivated. (Colors are for moist soil unless otherwise stated.)

Ap--0 to 9 inches; black (10YR 2/1) ashy loam, dark gray (10YR 4/1) dry; weak fine granular structure; soft, friable, slightly sticky and slightly plastic; many fine roots; many very fine tubular pores; 10 percent gravel; slightly effervescent; slightly alkaline (pH 7.6); clear wavy boundary.

A--9 to 19 inches; very dark brown (10YR 2/2) ashy loam, dark grayish brown (10YR 4/2) dry; weak fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many very fine tubular pores; 14 percent gravel; about 25 percent of the volume consists of black (10YR2/1) krotovinas; neutral (pH 7.2); clear wavy boundary. (Combined thickness of the A horizon is 10 to 29 inches)

Bw1--19 to 25 inches; dark brown (7.5YR 3/3) loam, brown (7.5YR 4/3) dry; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine roots; many very fine tubular pores; 14 percent gravel; about 14 percent of the volume consists of black krotovinas; neutral (pH 6.8); clear wavy boundary.

Bw2--25 to 35 inches; dark reddish brown (5YR 3/3) loam, reddish brown (5YR 4/3) dry; weak medium prismatic structure parting to moderate medium subangular blocky; hard, friable, moderately sticky and moderately plastic; common fine roots; many very fine tubular pores; 13 percent gravel; neutral (pH 6.8); abrupt wavy boundary. (Combined thickness of the Bw horizon ranges from 10 to 23 inches)

2C--35 to 60 inches; dark reddish brown (5YR 3/4) extremely gravelly loam, reddish brown (5YR 4/4) dry; massive; hard, firm, slightly brittle, moderately sticky and moderately plastic; few fine roots; many very fine tubular pores; 45 percent gravel, 20 percent cobbles and 10 percent stones; neutral (pH 6.9).

TYPE LOCATION: Wallowa County, Oregon; about 5 miles southeast of Enterprise; 2,620 feet south and 1,450 feet east of the northwest corner of section 22, T. 2 S., R. 44 E. (Latitude 45 degrees, 22 minutes, 28 seconds N, Longitude 117 degrees, 18 minutes, 14 seconds W) USGS Chief Joseph Mountain, Oregon 7.5 minute Topographic Quadrangle.

RANGE IN CHARACTERISTICS: The soils are usually moist, but are dry in all parts of the moisture control section for 60 to 90 consecutive days following the summer solstice in most years. The mean annual soil temperature is 44 to 47 degrees F. The particle-size control section averages 18 to 30 percent clay and less than 35 percent rounded or subrounded rock fragments (weighted average) and more than 15 percent coarser than very fine sand. Depth to the extremely gravelly substratum ranges from 30 to 40 inches. Thickness of the mollic epipedon is 20 to 40 inches and includes all or part of the Bw horizon. Depth to bedrock is 60 inches or more.

The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 1 or 2 moist and dry. It is ashy loam or ashy silt loam with 5 to 15 percent clay. It has 0 to 20 percent gravel, 0 to 15 percent cobbles, and 0 to 10 percent stones. It has 20 to 30 percent volcanic glass and glass coated aggregate and less than 0.4 percent acid oxalate extractable aluminum plus one-half iron. Soil reaction is slightly acid to moderately alkaline.

The Bw horizon has hue of 5YR, 7.5YR, or 10YR, value of 3 or 4 moist, 4 or 5 dry, and chroma of 3 or 4 moist and dry. It is silt loam, loam or clay loam with 18 to 35 percent clay. It has 0 to 15 percent gravel. Organic matter is 1 to 2 percent. Soil reaction is slightly acid or neutral.

The 2C or 2BC horizon has colors similar to the Bw horizon. It is sandy loam, loam, sandy clay loam, or clay loam with 15 to 30 percent clay. It has 15 to 45 percent gravel, 0 to 25 percent cobbles, and 0 to 15 percent stones. Soil reaction is slightly acid or neutral.

COMPETING SERIES: This is the Buford, Derr (T), Hall Ranch, Kahler, McGarr and Myzel (T) series.

Buford soils - 40 to 60 inches to lithic contact (basalt)

Derr soils - 20 to 40 inches to lithic contact (shale)

Hall Ranch soils - 20 to 40 inches to paralithic contact (weathered andesite)

Highvalley soils - vitrandic influence greater than 40 inches thick; 0 to 15 percent angular rock fragments from basalt colluvium origin

The Kahler soils - have 10 to 20 percent volcanic glass; lack a 2C horizon with greater than 35 percent rock fragments within 40 inches; have less than 35 percent angular rock fragments from basic igneous and metamorphic colluvium origin

McGarr soils - 20 to 40 inches to lithic contact (basalt)

Myzel soils - aquic conditions and redox features at a depth of 30 to 48 inches; irregular decrease in organic matter

GEOGRAPHIC SETTING: The Minam soils are on alluvial or pediment fans. Slopes are 0 to 15 percent. They formed in mixed alluvium and colluvium with an influence of volcanic ash and loess. Elevation is 3,400 to 5,300 feet. The climate is characterized by cold wet winters and hot dry summers. The mean annual precipitation is 12 to 30 inches. The mean annual temperature is 40 to 45 degrees F. The frost-free period is 50 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ferguson, Lostine, Parsnip, Redmount, and Rondowa soils. Ferguson soils are on higher adjacent outwash fans, are ashy over loamy-skeletal, and are dry for less than 45 consecutive days following the summer solstice. Lostine soils are on lower adjacent outwash plains, terraces, and fans and are coarse-silty. Parsnip soils are on adjacent higher plateaus and have bedrock at a depth of 10 to 20 inches. Redmount soils are on adjacent lower outwash plains and are coarse-loamy. Rondowa soils are on slightly lower glacial moraines and are loamy-skeletal.

DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: The soils are used mainly for irrigated hay, pasture, small grains, and limited timber production. The potential native vegetation is Idaho fescue, bluebunch wheatgrass, and small amounts of forbs. In forested areas, it is ponderosa pine, Douglas fir, larch, and grand fir.

DISTRIBUTION AND EXTENT: Northeastern Oregon, MLRA 9 and 10. The series is of small extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Harney County, Oregon, 1997.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Mollic (Pachic) epipedon - the zone from the surface to a depth of 35 inches (Ap, A, Bw1, and Bw2 horizons). Organic matter is 1 to 7 percent based on lab data.
Vitrandic feature - the zone from 0 to 19 inches (Ap and A horizons) based on laboratory data from geographically associated soils.
Particle-size control section - the zone from 10 to 40 inches (A, Bw1, Bw2, and upper 2C horizons) averaging 14 percent rock fragments.
Mixed mineralogy based on 15-bar to clay ratio of less than 0.6 from 19 to 60 inches.
Classification revised 08/01 by adding CEC activity class based on issue #18 of Soil Taxonomy.

ADDITIONAL DATA: Characterization data on two profiles (S64 Oreg-32-8 and 9) reported in Riverside Soil Survey Laboratory Report for soils from Wallowa County, Oregon, July 1966.

National Cooperative Soil Survey
U.S.A.