LOCATION PITSUA OR
Tentative Series
IRD. AGG/DEW
08/2025
PITSUA SERIES
Landscape--Eastern Cascade mountains, Paulina Mountains
Landform--lava flows, lava plains, mountain slopes or knobs
Slope--0 to 50 percent slopes
Parent Material--volcanic ash over basalt bedrock
Mean annual precipitation--640 mm
Mean annual air temperature--5.8 degrees C
Depth class--moderately deep
Drainage class--well drained
Soil moisture regime--xeric
Soil temperature regime--cryic
Soil moisture subclass--typic
TAXONOMIC CLASS: Ashy, glassy Humic Xeric Vitricryands
TYPICAL PEDON: Pitsua ashy sandy loam, forested, on a 12 percent slope at an elevation of 1426 meters. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 2 centimeters; slightly decomposed plant material; strongly acid (pH 5.5); abrupt smooth boundary.
A1--2 to 11 centimeters; dark grayish brown (10YR 4/2) ashy sandy loam, very dark grayish brown (10YR 3/2) moist; weak coarse granular structure; soft, very friable, nonsticky, nonplastic; many very fine and common fine roots throughout; many fine irregular pores; 2 percent fine gravels; slightly acid (pH 6.4); clear smooth boundary.
A2--11 to 28 centimeters; brown (10YR 5/3) ashy sandy loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; common fine roots throughout; many fine irregular pores; 4 percent fine gravel; neutral (pH 6.6); gradual smooth boundary.
Bw1--28 to 44 centimeters; yellowish brown (10YR 5/4) ashy sandy loam, dark yellowish brown (10YR 3/4) moist; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; few medium and common fine roots throughout; common medium and few fine irregular pores; 5 percent fine gravel; neutral (pH 6.8); gradual smooth boundary.
Bw2--44 to 63 centimeters; grayish brown (10YR 5/2) gravelly ashy sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure parts to single grain; loose, nonsticky, nonplastic; few fine and coarse roots throughout; common medium and few fine irregular pores; 16 fine gravel; neutral (pH 6.8); abrupt irregular boundary.
2R--63 centimeters; basalt bedrock.
TYPE LOCATION: Deschutes County, Oregon; NE 1/4, SE 1/4 of section of 12, T. 19 S, R. 10 E; Latitude 43.9418610, Longitude -121.4686390 datum WGS84 (coordinates determined with a GPS).
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--5.2 to 7.6 degrees C
Soil moisture--usually moist in winter and spring, dry in the moisture control section for 45 to 60 days in the 4 months following the summer solstice
Depth to lithic contact--50 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--55 to 90 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--1 to 8 percent
Fragment content, weighted average--0 to 35 percent
A horizons
Hue--10YR
Value--4 or 5 dry, 2 or 3 moist
Chroma--1 to 3
Fine earth texture--ashy loamy sand or ashy sandy loam
Clay content--1 to 8 percent
Sand content--55 to 90 percent
Organic matter--1 to 4 percent
Total fragment content--0 to 30 percent
Gravel--0 to 20 percent
Pumice paragravel--0 to 10 percent
Reaction--6.1 to 7.3 (slightly acid to neutral)
Thickness--combined thickness of A horizons is 18 to 30 cm
Bw horizons
Hue--10YR
Value--4 or 5 dry, 3 or 4 moist
Chroma--3 or 4
Fine earth texture--ashy loamy sand or ashy sandy loam
Clay content--1 to 8 percent
Sand content--55 to 90 percent
Organic matter--0.1 to 0.5 percent
Total fragment content--0 to 35 percent
Gravel--0 to 25 percent
Pumice paragravel--0 to 10 percent
Cobble--0 to 10 percent
Stone--0 to 5 percent
Reaction--6.1 to 7.3 (slightly acid to neutral)
Thickness--combined thickness of B horizons is 20 to 80 cm
COMPETING SERIES:
Cornucopiapeak--less than 55 percent sand throughout particle-size control section
Cultus--lithic contact below 150 cm
Hophman--lithic contact between 100 or 150 cm; episaturation between 100 and 150 cm from the mineral soil surface during later winter and spring
Shroyton--lithic contact between 100 and 150 cm
GEOGRAPHIC SETTING:
Elevation--1250 to 1900 m
Climate--cold, wet winters and cool, dry summers
Mean annual precipitation--460 to 890 mm
Mean annual air temperature--5.0 to 6.2 degrees C
Frost-free period--20 to 70 days
Lithology--volcanic ash derived from Mazama
GEOGRAPHICALLY ASSOCIATED SOILS:
Kawak--occurs on lava flows, mountain slopes, knobs; 25 to 50 cm to lithic contact
Shroyton--occurs on mountain slopes; 100 to 150 cm to lithic contact
Wanoga--occurs at lower elevations on lava flows
Henkle--occurs at lower elevations on lava flows; greater than 35% fragments in the particle size control section
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage--well drained
Saturated hydraulic conductivity (Ksat)--high to very high
USE AND VEGETATION:
Use--timber production, wildlife habitat
Vegetation--lodgepole pine, Ponderosa pine, white fir, antelope bitterbrush, greenleaf manzanita, western needlegrass, bottlebrush squirreltail
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 Pitsua Butte in the Deschutes National Forest
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Particle-size control section--2 to 63 cm (A1, A2, Bw1, and Bw2 horizons)
Mollic epipedon--2 to 28 cm (A1 and A2 horizons)
Cambic horizon--28 to 63 cm (Bw1 and Bw2 horizons)
Andic soil properties--2 to 63 cm (A1, A2, Bw1, and Bw2 horizons)
Lithic contact--63 cm
National Cooperative Soil Survey
U.S.A.