LOCATION MELHORN                 OR

Established Series
Rev. AEK/RJO/DAL
03/2013

MELHORN SERIES

The Melhorn series consists of very deep, well drained soils on plateaus and mountains. Melhorn soils are formed in volcanic ash and loess overlying colluvial material derived from basalt. Slopes are 0 to 60 percent. The mean annual precipitation is about 23 inches and the mean annual temperature is about 43 degrees F.

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

TYPICAL PEDON: Melhorn ashy silt loam, woodland, on a 34 percent northwest - facing slope at an elevation of 3,640 feet. (Colors are for moist soil unless otherwise noted.)

Oi--2 to 0 inches; needles and twigs.

A1--0 to 7 inches; dark brown (7.5YR 3/2) ashy silt loam, brown (7.5YR 4/2) dry; weak medium and coarse subangular blocky structure; soft, friable, slightly sticky and nonplastic; common very fine and few fine and medium roots; few fine irregular and few fine tubular pores; 5 percent gravel; slightly acid (pH 6.5); clear irregular boundary.

A2--7 to 19 inches; dark brown (7.5YR 3/2) ashy silt loam, brown (7.5YR 5/4) dry; moderate medium and coarse subangular blocky structure; soft, friable, slightly sticky and nonplastic; common fine and very fine and few coarse roots; common fine irregular and few fine tubular pores; 5 percent gravel; slightly acid (pH 6.5); clear irregular boundary (Combined thickness of A horizon is 10 to 20 inches).

Bt1--19 to 28 inches; brown (7.5YR 4/4) gravelly loam, brown (7.5YR 5/4) dry; strong medium and coarse subangular blocky structure; slightly hard, firm, moderately sticky and slightly plastic; common distinct clay films on ped faces; few very fine, fine, medium, and coarse roots; common fine irregular and few fine tubular pores; 15 percent gravel; slightly acid (pH 6.5); clear smooth boundary (9 to 34 inches thick).

Bt2--28 to 43 inches; strong brown (7.5YR 4/6) gravelly clay loam, strong brown (7.5YR 5/6) dry; strong medium and coarse subangular blocky structure; hard, very firm, moderately sticky and moderately plastic; many distinct clay films on ped faces; few very fine and fine and common coarse roots; common fine irregular pores; 15 percent gravel; slightly acid (pH 6.1).

Bt3--43 to 72 inches; strong brown (7.5YR 4/6) gravelly clay loam, strong brown (7.5YR 5/6) dry; moderate medium and coarse subangular blocky structure; hard, firm, moderately sticky and slightly plastic; common distinct clay films on ped faces; few very fine and fine and common coarse roots; common fine irregular pores; 15 percent gravel; slightly acid (pH 6.1). (Combined thickness of the Bt2 and Bt3 horizon is 20 to 40 inches.)

TYPE LOCATION: Baker County, Oregon, about 1,850 feet west and 265 feet south of the northeast corner of section 15, T. 7 S., R. 46 E. (Latitude - 44 degrees, 57 minutes, 46 seconds N., and Longitude - 117 degrees, 4 minutes, 11 seconds W.); USGS Halfway Quadrangle.

RANGE IN CHARACTERISTICS:
Soil moisture - usually moist but are dry for 45 to 75 consecutive days in the summer
Mean annual soil temperature - 42 to 47 degrees F.
Particle-size control section - 18 to 35 percent clay and 10 to 35 percent rock fragments
Mollic epipedon - 10 to 20 inches thick
Depth to bedrock - 60 inches or more

Vitrandic feature thickness - 10 to 20 inches
Organic matter - 1 to 4 percent
Acid-oxalate extractable aluminum plus one-half iron - 0.5 to 1.5 percent
Phosphate retention - 35 to 45 percent
Particles of 0.02 to 2.0 mm - 40 to 60 percent
Volcanic glass content - 5 to 20 percent
15-bar water retention on air-dried sample - 15 to 25 percent

A1 horizon
Hue - 7.5YR or 10YR
Value - 2 or 3 moist, 3 or 4 dry
Chroma - 2 or 3 moist or dry
Texture - ashy SIL
Rock fragments - 0 to 15 percent gravel
Clay - 10 to 20 percent
Reaction - 6.1 to 7.3

A2 horizon and A3 horizon (when present)
Hue - 7.5YR or 10YR
Value - 2 or 3 moist, 3 to 5 dry
Chroma - 2 or 3 moist, 3 or 4 dry
Texture - ashy SIL, ashy L, GR-ashy L, GR-ashy SIL
Rock fragments - 5 to 20 percent gravel
Clay - 10 to 20 percent
Reaction - 6.1 to 7.3

Bt1 horizon
Hue - 7.5YR or 10YR
Value - 3 or 4 moist, 4 or 5 dry
Chroma - 3 or 4 moist, 4 or 5 dry
Texture - GR-L, GR-SIL, CB-L, L, SIL, CB-SIL
Rock fragments - 5 to 30 percent total with 5 to 15 percent gravel and 0 to 15 percent cobbles
Clay - 18 to 27 percent
Reaction - 6.1 to 7.3

Bt2 and Bt3 horizons
Hue - 7.5YR or 10YR
Value - 4 or 5 moist or dry
Chroma - 4 to 6 moist, 5 or 6 dry
Texture - GR-CL, CL, L, GR-L, CB-CL, CB-L, GR-SIL, CB-SICL, SIL, CB-SIL, GR-SICL
Rock fragments - 10 to 35 percent total with 10 to 25 percent gravel and 0 to 15 percent cobbles
Clay - 18 to 35 percent
Reaction 6.1 to 7.3

COMPETING SERIES: These are Bly, Hess, Lidos, Raycreek (T), Salcreek and Vangoe (T) soils.

Bly soils - greater than 40 inches to duripan; mollic epipedon 20 to 30 inches thick
Hess soils - 40 to 60 inches to lithic contact (welded tuff)
Lidos soils - 30 to 60 inches to buried coarse-loamy Eb horizon and clayey 3Btb genetic horizon
Raycreek soils - 20 to 40 inches to lithic contact (tuff), mollic epipedon 20 to 30 inches thick
Salcreek soils - have a particle-size control section with greater than 50 percent sand and 15 to 30 percent metasedimentary and rounded glacial till derived rock fragments
Vangoe soils - 40 to 60 inches to lithic contact (basalt); mollic epipedon 20 to 33 inches thick

GEOGRAPHIC SETTING: Melhorn soils occur on summits and backslopes of plateaus and mountains. Elevations are 2,500 to 5,500 feet. Slopes are 0 to 60 percent. The soil is formed in volcanic ash and loess overlying colluvial material derived from basalt. The climate is characterized by cold, wet winters and warm, dry summers. The mean annual precipitation is 15 to 30 inches. The mean annual temperature is 40 to 45 degrees F. The frost-free period is 60 to 110 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Getaway, Kamela and Klicker soils. Getaway soils are on steep side slopes and are loamy-skeletal. Kamela soils are on steep side slopes, have an ochric epipedon, and more than 35 percent coarse fragments in the particle-size control section. Klicker soils are moderately deep, have more than 35 percent coarse fragments, and are on steep convex side slopes.

DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.

USE AND VEGETATION: These soils are used for watershed, wildlife habitat, timber production, livestock grazing and recreation. The native vegetation is grand fir, Douglas fir, ponderosa pine, birchleaf spirea, common snowberry, mountain snowberry, common chokecherry, western serviceberry, bitter cherry, ceanothus, Rocky Mountain maple, showy aster, heartleaf arnica, mountain sweet cicely, bracken fern, side-flowered miterwort, dogbane, woods strawberry, mountain brome and pinegrass.

DISTRIBUTION AND EXTENT: Northeastern Oregon; MLRA 9 and 10. The soils are of limited extent.

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

SERIES ESTABLISHED: Wallowa County, Oregon; 1998. The name is from a hill in Pine Valley.

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

Mollic epipedon - from 0 to 19 inches (A1 and A2 horizons)
Argillic horizon - from 19 to 72 inches (Bt1, Bt2, Bt3 horizons)
Vitrandic feature - from 0 to 19 inches
Particle-size control section - from 19 to 39 inches (Bt1 and part of Bt2 horizon)

The dominant USFS plant association is PSME/SPBE; others may include ABGR/SPBE, PSME/PHMA and ABGR/ACGL/PHMA

ADDITIONAL DATA: Laboratory data is available for this soil. NSSL pedon number S95OR-001-009, Lincoln, NE.

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National Cooperative Soil Survey
U.S.A.