LOCATION KOTZMAN OR
Tentative Series
IRD. KLM/AGG/DEW
08/2025
KOTZMAN SERIES
Landscape--Eastern Cascade mountains
Landform--lava flows or lava plains
Slope--0 to 25 percent
Parent Material--pumice and volcanic ash over basalt bedrock
Mean annual precipitation--310 mm
Mean annual air temperature--6 degrees C
Depth class--moderately deep
Drainage class--somewhat excessively drained
Soil moisture regime--xeric
Soil temperature regime--cryic
Soil moisture subclass--typic
TAXONOMIC CLASS: Ashy-pumiceous, glassy Xeric Vitricryands
TYPICAL PEDON: Kotzman ashy loamy coarse sand, forested, on a 2 percent slope at an elevation of 1510 meters. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 3 centimeters; slightly decomposed plant material; very strongly acid (pH 5.0); abrupt smooth boundary.
A--3 to 12 centimeters; gray (10YR 5/1) ashy loamy coarse sand, dark grayish brown (10YR 4/2) moist; weak medium granular structure; soft, very friable, nonsticky, nonplastic; common very fine roots throughout; many very fine and fine interstitial pores; 10 percent pumice paragravel; slightly acid (pH 6.5); clear wavy boundary.
C1--12 to 50 centimeters; very pale brown (10YR 8/2) extremely paragravelly ashy coarse sand, light brownish gray (10YR 6/2) moist; single grain; loose, nonsticky, nonplastic; few very fine and coarse roots throughout; many very fine, fine, and medium interstitial pores; 85 percent pumice paragravel; neutral (pH 6.7); clear smooth boundary.
C2--50 to 58 centimeters; white (10YR 8/1) extremely paragravelly ashy coarse sand, very pale brown (10YR 8/2) moist; single grain; loose, nonsticky, nonplastic; few very fine and coarse roots throughout; many very fine, fine, and medium interstitial pores; 70 percent pumice paragravel; neutral (pH 6.7); abrupt smooth boundary.
2Bwb--58 to 75 centimeters; brown (10YR 5/3) ashy sandy loam, dark brown (10YR 3/3) moist; moderate fine subangular blocky and moderate medium subangular blocky structure; soft, friable, nonsticky, nonplastic; few very fine and medium roots throughout; few very fine interstitial and few fine dendritic tubular pores; neutral (pH 7.2); abrupt smooth boundary.
3R--75 centimeters; basalt bedrock.
TYPE LOCATION: Deschutes County, Oregon; SW 1/4, NE 1/4 section 31, T. 21 S., R. 16 E.; Latitude 43.7103410, Longitude -121.0659090, datum WGS84 (coordinates determined with a GPS).
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--5 to 7 degrees C
Soil moisture--usually moist in winter and spring, dry in the moisture control section for 45 to 75 days in the 4 months following the summer solstice
Depth to buried Mazama ash--50 to 75 cm
Depth to lithic contact--60 to 100 cm
Thickness of ash influenced layers--50 to 100 cm
Estimated properties of layers influenced by volcanic ash
Ammonium oxalate extractable Al + Fe--0.4 to 1.6 percent
1500 kPa water content (air dry)--3 to 12 percent
0.02 to 2.0 mm fraction--60 to 95 percent
Medium to very coarse sand in the .02 to 2.0 mm fraction--greater than 50 percent
Volcanic glass in the 0.02 to 2.0 mm fraction--40 to 80 percent
P retention--25 to 35 percent
Particle-size control section: mineral soil surface to lithic contact (3 to 75 cm)
Clay content, weighted average--0 to 4 percent
Fragment content, weighted average--50 to 90 percent
A horizon
Hue--10YR or 2.5Y
Value--3 or 4 moist, 4 to 6 dry
Chroma--1 to 3
Fine earth texture--ashy loamy sand or ashy loamy coarse sand
Clay content--0 to 4 percent
Sand content--75 to 85 percent
Organic matter--0.50 to 2.0 percent
Total fragment content--5 to 60 percent
Pumice paragravel--5 to 60 percent
Reaction--6.1 to 7.3 (slightly acid to neutral)
Thickness--8 to 20 cm
C horizons
Hue--10YR or 2.5Y
Value--5 to 7 moist, 6 to 8 dry
Chroma--1 to 4
Fine earth texture--ashy loamy sand, ashy loamy coarse sand or ashy coarse sand
Clay content--0 to 4 percent
Sand content--75 to 95 percent
Organic matter--0.0 to 1.0 percent
Total fragment content--50 to 90 percent
Pumice paragravel--50 to 90 percent
Reaction--6.6 to 7.3 (neutral)
Combined thickness of C horizons--30 to 80 cm
2Bwb horizon (when present)
Hue--10YR or 2.5Y
Value--3 or 4 moist, 4 to 5 dry
Chroma--2 to 4
Fine earth texture--ashy sandy loam or ashy loamy sand
Clay content--2 to 15 percent
Sand content--60 to 85 percent
Organic matter--0.0 to 1.0 percent
Total fragment content--0 to 40 percent
Pumice paragravel (fine)--0 to 10 percent
Gravel--0 to 40 percent
Cobble--0 to 40 percent
Reaction--6.6 to 7.3 (neutral)
Thickness--0 to 30 cm
COMPETING SERIES:
Lapine--greater than 150 cm to root restrictive layer
Maklak-- greater than 150 cm to root restrictive layer; contains cobble size pumice parafragments
Shadypass--greater than 150 cm to root restrictive layer; Al+1/2Fe acid oxalate of greater than 2.0 percent
Wedge-- greater than 150 cm to root restrictive layer; Al+1/2Fe acid oxalate of greater than 2.0 percent
GEOGRAPHIC SETTING:
Elevation--1400 to 1525 m
Climate--cold, wet winters and cool, dry summers
Mean annual precipitation--280 to 410 mm
Mean annual air temperature--3.0 to 6.5 degrees C
Frost-free period--20 to 50 days
Lithology--volcanic pumice and ash derived from Newberry Caldera over volcanic ash derived from Mazama
GEOGRAPHICALLY ASSOCIATED SOILS:
Deadwilma--occurs on basins and lava flows; greater than 150 cm to root restriction
Henkle--occurs on lava flows; lacks pumice paragravel, 25 to 50 cm to lithic contact
Ipsoot--occurs on cinder cones; 50 to 100 cm to cinder
Lapine--occurs on lava plains; averages 35 to 60 percent pumice paragravel in the particle-size control section
Moffitt--occurs in complex on concave positions of lava flows and mountain slopes; greater than 150cm to root restriction
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage--somewhat excessively drained
Saturated hydraulic conductivity (Ksat)--high to very high
USE AND VEGETATION:
Use--timber production, wildlife habitat
Vegetation--lodgepole pine, Ponderosa pine, antelope bitterbrush, western needlegrass
DISTRIBUTION AND EXTENT:
East slopes of the Cascade Mountains in central Oregon; MLRA 06; small extent
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED:
Deschutes County, Deschutes National Forest, Oregon 2025; name derived from Kotzman Basin
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Particle-size control section--3 to 75 cm (A, C1, C2, and 2Bwb horizons)
Ochric epipedon--3 to 12 cm (A horizon)
Andic soil properties--3 to 75 cm (A, C1, C2, and 2Bwb horizons)
Lithic contact--75 cm
National Cooperative Soil Survey
U.S.A.