LOCATION LONGBOW OR
Tentative Series
DRJ/KMS
02/2025
LONGBOW SERIES
Landscape--western Cascade Mountains
Landform--mountains, complex landslides
Slope--0 to 30 percent
Parent material--colluvium and till derived from volcanic rocks mixed with volcanic ash
Mean annual precipitation--about 2600 mm
Mean annual air temperature--about 6 degrees C
Depth class-very deep
Drainage class--well drained
Soil moisture regime--udic
Soil temperature regime--cryic
Soil moisture subclass--typic
TAXONOMIC CLASS: Medial, amorphic Typic Haplocryands
TYPICAL PEDON: Longbow medial loam on a 13-percent, forested slope at an elevation of 1140 m
Oi--0 to 2 cm; slightly decomposed plant material; abrupt wavy boundary
A--2 to 35 cm; medial loam, brown (7.5YR 4/2) dry, dark brown (7.5YR 3/2) moist; moderate fine granular structure; very friable, loose, slightly sticky and nonplastic; many very fine, common medium and coarse, and few fine roots; many very fine and fine irregular pores and common medium and coarse tubular pores; 10 percent gravel; strongly acid (pH 5.3); clear wavy boundary
AB--35 to 59 cm; gravelly medial silt loam, yellowish brown (10YR 5/4) dry, brown (10YR 4/3) moist; moderate very fine subangular blocky structure; very friable, loose, slightly sticky and slightly plastic; many very fine, common medium, and few fine and coarse roots; many very fine dendritic tubular and irregular pores and common fine, medium, and coarse tubular pores; 15 percent gravel and 5 percent cobbles; strongly acid (pH 5.5); clear wavy boundary
Bw1--59 to 82 cm; gravelly medial silt loam, light yellowish brown (10YR 6/4) dry, brown (10YR 4/3) moist; moderate fine subangular blocky structure; friable, slightly hard, slightly sticky and slightly plastic; common very fine and few fine and medium roots; common very fine and fine dendritic tubular pores and common very fine and fine and few medium tubular pores; 15 percent gravel and 5 percent cobbles; moderately acid (pH 5.7); gradual wavy boundary
Bw2--82 to 150 cm; cobbly medial silt loam, light yellowish brown (10YR 6/4) dry, dark yellowish brown (10YR 4/4) moist; moderate medium subangular blocky structure; friable, slightly hard, slightly sticky and slightly plastic; few very fine and fine roots; common very fine and fine dendritic tubular pores and common very fine and fine and few medium tubular pores; 10 percent gravel and 15 percent cobbles; moderately acid (pH 5.8)
TYPE LOCATION: Linn County, Oregon, about 36 km east of Sweet Home and 7.5 km northeast of the junction of Upper Soda Fork Road and OR Highway 20; about 255 m south and 335 m east of the northwest corner of section 9, T. 13 S., R. 5 E.; latitude 44.45825, longitude -122.22269, datum WGS 84 (coordinates determined with a GPS)
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--5 to 8 degrees C
Thickness of umbric epipedon--25 to 50 cm
Reaction--pH 5.1 to 6.0
Estimated properties of layers with andic soil properties
*Ammonium oxalate extractable Al plus 1/2 Fe--2.0 to 4.0 percent
*Particles 0.02 to 2.0 mm diameter--greater than 30 percent of the fine-earth fraction
*Volcanic glass content in 0.02 to 2.0-mm fraction--5 to 30 percent
*Phosphate retention--85 to 100 percent
*15-bar water retention--30 to 70 percent (undried samples), greater than 15 percent (dried samples)
*1/3-bar bulk density--0.6 to 1.1 g/cm3
Particle-size control section (weighted average)
*Clay content--18 to 27 percent
*Total rock fragments--5 to 35 percent
Oi horizon
*Thickness--1 to 10 cm
A horizon
*Hue--7.5YR, 10YR
*Value--2 to 3 moist, 3 to 5 dry
*Chroma--2 or 3 moist or dry
*Fine-earth texture--medial loam, medial silt loam
*Clay content--15 to 22 percent
*Sand content--25 to 45 percent
*Total fragment content--5 to 35 percent
*Gravel content--5 to 30 percent
*Cobble content--0 to 10 percent
*Thickness--20 to 36 cm
AB horizon, and BA horizon (where present)
*Hue--10YR, 7.5YR
*Value--3 or 4 moist, 4 to 6 dry
*Chroma--3 or 4 moist or dry
*Fine-earth texture--medial silt loam, medial loam
*Clay content--15 to 22 percent
*Sand content--20 to 40 percent
*Total fragment content--5 to 35 percent
*Gravel content--5 to 30 percent
*Cobble content--0 to 10 percent
*Thickness--0 to 30 cm
Bw1 horizon
*Hue--2.5Y, 10YR, 7.5YR
*Value--3 or 4 moist, 5 or 6 dry
*Chroma--3 or 4 moist, 3 to 6 dry
*Fine-earth texture--medial silt loam, medial loam
*Clay content--18 to 27 percent
*Sand content--15 to 35 percent
*Total fragment content--5 to 35 percent
*Gravel content--5 to 30 percent
*Cobble content--0 to 15 percent
*Stone content--0 to 5 percent
*Thickness--15 to 60 cm
Bw2 horizon
*Hue--2.5Y, 10YR, 7.5YR
*Value--3 to 5 moist, 5 to 7 dry
*Chroma--3 or 4 moist, 3 to 6 dry
*Fine-earth texture--medial silt loam, medial loam
*Clay content--18 to 27 percent
*Sand content--15 to 35 percent
*Total fragment content--5 to 50 percent
*Gravel content--5 to 35 percent
*Cobble content--0 to 20 percent
*Stone content--0 to 5 percent
COMPETING SERIES:
Cruiser--ochric epipedon
Molawa--ochric epipedon
Keel--depth to lithic contact is 50 to 100 cm
Oneonta--umbric epipedon greater than 50 cm thick
Soosap--depth to paralithic contact is 50 to 100 cm
GEOGRAPHIC SETTING:
Elevation--980 to 1525 m
Climate--cold, wet winters; mild, dry summers
Mean annual precipitation--1500 to 3600 mm
Mean annual air temperature--4 to 7 degrees C
Frost-free period--60 to 105 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Icecap--50 to 100 cm to lithic contact; located in convex positions on mountain slopes and mountaintops
Idanha--averages greater than 35 percent rock fragments in the particle-size control section; located on mountain slopes
Blowout--depth to aquic conditions ranges from 50 to 100 cm below the mineral soil surface; located on complex landslides
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained
Flooding--none
Ponding--none
Saturated hydraulic conductivity (Ksat)--high
USE AND VEGETATION:
Use--timber production, water supply, wildlife habitat, recreation
Potential natural vegetation--Douglas-fir, western hemlock, Pacific silver fir, noble fir, Pacific rhododendron, Cascade barberry, Alaska blueberry, bunchberry dogwood, starry false lily of the valley, pipsissewa, twinflower
DISTRIBUTION AND EXTENT: Western Cascade Mountains, Oregon; MLRA 3; moderate extent
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Willamette National Forest, Linn County, Oregon; name from a campground in Linn County
REMARKS:
Diagnostic horizons and other features in this pedon
*Particle-size control section--zone from 2 to 102 cm
*Umbric epipedon--zone from 2 to 35 cm
*Cambic horizon--zone from 35 to 150 cm
*Andic soil properties--zone from 2 to 150 cm
*Volcanic glass--zone from 2 to 150 cm
09/2023--all mineral horizons meet criteria #3 for andic soil properties in the 13th edition of Keys to Soil Taxonomy. All pedons have third-bar bulk density low enough to also meet criteria #2 (no ash required) throughout the umbric epipedon, and some pedons meet criteria #2 throughout the profile.
ADDITIONAL DATA: Type location user site ID--2013OR043024
National Cooperative Soil Survey
U.S.A.