LOCATION SOAPGRASS OR
Tentative Series
IRD. DRJ/KMS/DCR
02/2025
SOAPGRASS SERIES
Landscape--western Cascade mountains, High Cascade mountains
Landform--colluvial aprons, cirque floors, cirque headwalls, glacial-valley walls, mountain slopes
Slope--0 to 90 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 5 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: Soapgrass medial loam, on the lower third of a forested 50 percent slope at an elevation of 1365 meters
Oi--0 to 3 centimeters; slightly decomposed plant material; abrupt wavy boundary
A1--3 to 25 centimeters; medial loam, brown (10YR 4/3) dry, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; common very fine and fine and few medium and coarse roots; many very fine and fine irregular, common medium and coarse tubular pores; 10 percent gravel; strongly acid (pH 5.1); gradual smooth boundary
A2--25 to 46 centimeters; medial loam, dark yellowish brown (10YR 4/4) dry, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; common very fine and fine and few medium and coarse roots; many very fine and fine irregular, common medium and coarse tubular pores; 10 percent gravel; strongly acid (pH 5.5); gradual wavy boundary
Bw1--46 to 103 centimeters; gravelly medial loam, brown (10YR 5/3) dry, dark brown (7.5YR 3/4) moist; weak very fine and fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and fine and few medium and coarse roots; common very fine and fine dendritic tubular and tubular and few medium and coarse tubular pores; 15 percent gravel, and 5 percent cobbles; moderately acid (pH 5.6); clear wavy boundary
Bw2--103 to 150 centimeters; very cobbly medial loam, yellowish brown (10YR 5/4) dry, brown (10YR 4/3) moist; weak coarse subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and fine and few medium and coarse roots; common very fine and fine dendritic tubular and tubular pores and few medium and coarse tubular pores; 30 percent gravel, 20 percent cobbles, and 5 percent stones; moderately acid (pH 5.7)
TYPE LOCATION: Linn County, Oregon, about 47 kilometers east of Sweet Home, OR and about 7 kilometers south of the junction of Forest Service road 15 and OR highway 20; 230 meters north and 45 meters east of the SW corner of section 19, T. 14 S., R. 6 E.; latitude 44.3333611, longitude -122.1473056, datum WGS84 (Coordinates determined with GPS)
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--4 to 8 degrees C
Thickness of the umbric epipedon--25 to 75 cm
Ammonium oxalate extractable Al plus 1/2 Fe--2.0 to 4.0 percent
Phosphate retention--greater than 85 percent
Volcanic glass content in the 0.02 to 2.0 mm fraction--5 to 30 percent
1/3 bar bulk density--0.6 to 1.1 g/cm3
15 bar water retention--greater than 15 percent (dried samples)
Fine-earth texture--medial loam, medial sandy loam
Clay content--7 to 18 percent
Sand content--35 to 60 percent
Reaction--pH 5.1 to 6.0
Base saturation (by ammonium acetate)--less than 35 percent
O horizon(s)
*Composition--slightly to moderately decomposed plant material
*Thickness--0 to 10 cm
A1 horizon
*Hue--7.5YR, 10YR
*Value--2 to 3 moist, 3 to 5 dry
*Chroma--2 or 3 moist and dry
*Total fragment content--0 to 35 percent
*Gravel content--0 to 35 percent
*Cobble content--0 to 10 percent
*Stone content--0 to 5 percent
*Thickness--20 to 36 cm
A2 or AB horizon
*Hue--10YR, 7.5YR
*Value--3 or 4 moist, 3 to 5 dry
*Chroma--2 to 4 moist, 3 to 6 dry
*Total fragment content--0 to 35 percent
*Gravel content--0 to 35 percent
*Cobble content--0 to 10 percent
*Stone content--0 to 5 percent
*Thickness--20 to 30 cm
Bw1 horizon
*Hue--10YR, 7.5YR
*Value--3 to 5 moist, 4 to 6 dry
*Chroma--3 to 6 moist, 4 to 6 dry
*Total fragment content--15 to 35 percent
*Gravel content--10 to 35 percent
*Cobble content--0 to 15 percent
*Stone content--0 to 5 percent
*Thickness--50 to 100 cm
Bw2 horizon
*Hue--2.5Y, 10YR, 7.5YR
*Value--4 to 6 moist and dry
*Chroma--3 to 6 moist and 4 to 6 dry
*Total fragment content--20 to 60 percent
*Gravel content--10 to 35 percent
*Cobble content--5 to 25 percent
*Stone content--0 to 10 percent
COMPETING SERIES:
Cruiser--averages 20 to 30 percent clay in the particle-size control section
Keel--50 to 100 cm to lithic contact
Longbow--averages 18 to 27 percent clay in the particle-size control section
Molawa--base saturation is 35 to 60 percent throughout the solum
Oneonta--clay content is greater than 18 percent in the lower part of the particle-size control section
Soosap--50 to 100 cm to paralithic contact
GEOGRAPHIC SETTING:
Elevation--1100 to 1900 meters
Climate--cool, dry summers; cold, wet winters
Mean annual precipitation--1500 to 3100 mm
Mean annual air temperature--3 to 7 degrees C
Frost-free period--45 to 105 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Chucksney--greater than 4 percent organic carbon throughout the upper 50 cm of an umbric epipedon; located on mountaintops and south-facing slopes
Hummington--50 to 100 cm to lithic contact; located on mountain slopes
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained
Saturation in normal years--none
Flooding--none
Ponding--none
Saturated hydraulic conductivity (Ksat)--high
USE AND VEGETATION:
Use--watershed, recreation, wildlife habitat, and timber production
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, and 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; the name is from Soapgrass Mountain in Linn County, Oregon.
REMARKS:
Diagnostic horizons and other features in this pedon
*Particle-size control section--zone from 3 to 103 cm
*Umbric epipedon--zone from 3 to 46 cm
*Cambic horizon--zone from 46 to 150 cm
*Andic soil properties--zone from 3 to 150 cm
*Volcanic glass--zone from 3 to 150 cm
06/2023--Reclassified from Medial, amorphic Humic Vitricryands to Medial, amorphic Typic Haplocryands. 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. Some pedons meet criteria #2 throughout the profile.
06/2016--Dense till was observed between 100 to 150 cm in some areas where Soapgrass was mapped in the Willamette National Forest.
Type location user site ID--2013OR043008
National Cooperative Soil Survey
U.S.A.