LOCATION SILVERASH OR

Established Series
Rev. MPK-TM-JVC-JBF
06/2011

SILVERASH SERIES

The Silverash series consists of very deep, poorly drained soils that formed in alluvium and lacustrine deposits derived from volcanic rocks and volcanic ash. Silverash soils are on depressions on plateaus and lakebeds. Slopes are 0 to 2 percent. The mean annual precipitation is about 280 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Fine, smectitic, frigid Aquandic Palexeralfs

TYPICAL PEDON: Silverash ashy fine sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.)

A--0 to 5 cm; pale brown (10YR 6/3) ashy fine sandy loam, dark brown (10YR 3/3) moist; moderate thick platy parting to weak thin platy structure; slightly hard, very friable, nonsticky and slightly plastic; few fine and medium roots; many very fine and common fine vesicular pores; slightly alkaline (pH 7.4); abrupt smooth boundary. (3 to 18 cm thick)

AE--5 to 20 cm; light brownish gray (10YR 6/2) ashy loam, dark grayish brown (10YR 4/2) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine and medium roots; few very fine vesicular and common fine interstitial and tubular pores; common faint dark gray (10YR 4/1) zones of iron depletion on faces of peds; slightly alkaline (pH 7.5); abrupt smooth boundary. (0 to 15 cm thick)

2Bt1--20 to 41 cm; light brown (7.5YR 6/3) clay, brown (7.5YR 4/2) moist; moderate medium prismatic parting to strong medium angular blocky structure; very hard, very firm, moderately sticky and very plastic; few medium roots; few fine tubular pores; common distinct clay films on faces of peds; slightly alkaline (pH 7.5); clear smooth boundary. (15 to 30 cm thick)

2Bt2--41 to 53 cm; pinkish gray (7.5YR 6/2) clay loam, brown (7.5YR 4/2) moist; weak medium prismatic parting to moderate medium angular blocky structure; hard, firm, moderately sticky and very plastic; few medium roots; few fine tubular pores; common distinct clay films on faces of peds; slightly alkaline (pH 7.6); clear smooth boundary. (13 to 25 cm thick)

3C1--53 to 97 cm; light brownish gray (10YR 6/2) sandy clay loam, dark grayish brown (10YR 4/2) moist; massive; very hard, firm, moderately sticky and moderately plastic; few medium roots; few very fine tubular pores; slightly alkaline (pH 7.8); gradual smooth boundary. (30 to 50 cm thick)

3C2--97 to 157 cm; light gray (10YR 7/2) very fine sandy loam, grayish brown (10YR 5/2) moist; massive; soft, very friable, slightly sticky and slightly plastic; few medium roots; common very fine and fine tubular pores; moderately alkaline (pH 8.0).

TYPE LOCATION: Lake County, Oregon; about 1.5 miles northeast of the northeastern corner of the Lost Forest Research Natural Area; approximately 2,100 feet south and 1,900 feet west of the northeast corner of section 18, T. 25 S., R. 21 E.; USGS Chicago Valley 7.5 minute topographic quadrangle; latitude 43 degrees 24 minutes 35 seconds N and longitude 120 degrees 14 minutes 35 seconds W NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in some part of the moisture control section from about mid-September through late July; xeric moisture regime that borders on aridic.
Mean annual soil temperature: 7 to 8 degrees C.
Aquic conditions: Occurs seasonally from the soil surface to a maximum depth of about 25 cm.
Depth to base of argillic horizon: 50 to 74 cm.
Abrupt textural change: An abrupt horizon boundary is normally present between the A or AE horizon and the 2Bt1 horizon accompanied by an absolute increase in clay content of 20 to 30 percent.

Particle-size control section - Clay content: Averages 35 to 50 percent.

A and AE horizons
Value: 6 or 7 dry, 3 through 5 moist.
Chroma: 1 through 3, dry or moist.
Clay content: 10 to 25 percent.
Redoximorphic features: Redox concentrations may occur as distinct and/or prominent masses of iron accumulation. Zones of iron and/or clay depletion are evident in many pedons as the low chroma matrix and on faces of peds.
Volcanic glass content: 30 to 60 percent in the coarse silt through fine sand fractions.
Reaction: Neutral or slightly alkaline.

2Bt horizons
Hue: 7.5YR through 2.5Y.
Value: 6 or 7 dry, 3 or 4 moist.
Chroma: 2 through 4, dry or moist.
Texture: Clay, silty clay loam, or clay loam.
Clay content: 35 to 50 percent.

3C horizons - Hue: 10YR or 2.5Y.
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 or 3, dry or moist.
Texture: Sandy clay loam, clay loam, very fine sandy loam.
Clay content: 18 to 35 percent.
Effervescence: Noneffervescent or slightly effervescent.
Reaction: Slightly alkaline through moderately alkaline.

COMPETING SERIES: There are currently no other series in this family.

GEOGRAPHIC SETTING: Silverash soils are on depressions on plateaus and lakebeds. These soils formed in alluvium and lacustrine deposits derived from volcanic rocks and volcanic ash. Slopes are 0 to 2 percent. Elevation ranges from 1,310 to 1,580 meters. The climate is characterized by cold, moist winters and warm, dry summers. The mean annual temperature is 6 to 7 degrees C, mean annual precipitation is 200 to 300 mm, and the frost-free period is 50 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chancelakes, Embal, Overallflat and Raztack soils. Chancelakes soils have cracks more than 1 cm wide that are open during summer and fall and have argillic horizons that are more than 100 cm thick. Embal soils do not have argillic horizons and have ashy textures and glassy mineralogy throughout. Overallflat soils are in a slightly higher position on the landscape and have an aridic soil moisture regime. Raztack soils do not have aquic conditions in the upper part and have duripans below 100 cm.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Poorly drained; negligible surface runoff; moderately low saturated hydraulic conductivity. Episaturation is present with perched free water between the soil surface and 20 cm (very shallow free water occurrence class) from January through July. Cumulative annual duration classes are Transitory or Common. These soils are susceptible to frequent ponding for long duration at some time between November through May with water depths of 0.3 to 30 cm.

USE AND VEGETATION: Silverash soils are used for livestock grazing and wildlife habitat. The vegetation is mainly silver sagebrush, Nevada bluegrass, creeping wildrye, and mat muhly.

DISTRIBUTION AND EXTENT: South-central Oregon. These soils are not extensive with about 7,300 acres of the series mapped to date. MLRA 23.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.

SERIES ESTABLISHED: Lake County (Northern Part), Oregon, 2006.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 20 cm (A and AE horizons).
Vitrandic intergrade feature - The zone from the soil surface to 20 cm(A and AE horizons).
Aquic conditions - The conditions of episaturation, reduction, and redoximorphic features between the soil surface and 20 cm at some time during normal years (A and AE horizons).
Argillic horizon - The zone from 20 to 53 cm (2Btl and 2Bt2 horizons).
Abrupt textural change - The abrupt clay increase of more than 20 percent at 20 cm (between the AE and 2Bt1 horizons).
Particle-size control section - The zone from 20 to 53 cm (2Btl and 2Bt2 horizons).

National Cooperative Soil Survey
U.S.A.