LOCATION OPPIO NV
Established Series
Rev. LIL-ELS-JVC-JBF
04/2017
OPPIO SERIES
The Oppio series consists of moderately deep, well drained soils that formed in residuum derived from volcanic rocks. Oppio soils are on mountains, hills, and plateaus. Slopes are 2 to 50 percent. The mean annual precipitation is about 250 mm and the mean annual temperature is about 9 degrees C.
TAXONOMIC CLASS: Fine, smectitic, mesic Xeric Haplargids
TYPICAL PEDON: Oppio cobbly sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 8 cm; pale brown (10YR 6/3) cobbly sandy loam, brown (10YR 4/3) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular and interstitial pores; 15 percent cobbles; slightly acid (pH 6.4); clear wavy boundary. (5 to 15 cm thick)
Bt1--8 to 20 cm; pale brown (10YR 6/3) clay loam, brown (10YR 4/3) moist; moderate fine prismatic structure parting to strong very fine subangular blocky; slightly hard, friable, very sticky and very plastic; common very fine roots; many very fine tubular and interstitial pores; few faint clay films on faces of peds and lining pores; neutral (pH 6.7); abrupt smooth boundary. (8 to 20 cm thick)
Bt2--20 to 36 cm; brown (10YR 5/3) clay, brown (10YR 4/3) moist; strong medium and coarse prismatic structure; very hard, firm, very sticky and very plastic; common very fine, fine, and medium roots; few very fine tubular pores; many distinct and few prominent clay films on faces of peds and lining pores; neutral (pH 6.6); clear irregular boundary. (10 to 28 cm thick)
Bt3--36 to 53 cm; pale brown (10YR 6/3) clay, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; very hard, firm, very sticky and very plastic; few very fine roots; few very fine tubular pores; many distinct and few prominent clay films on faces of peds and lining pores; neutral (pH 6.6); abrupt irregular boundary. (13 to 25 cm thick)
R--53 cm; fractured hard andesite bedrock; common very fine roots and few faint clay films lining fractures.
TYPE LOCATION: Washoe County, Nevada; about 4.5 miles north of Reno; approximately 2,200 feet north and 700 feet east of the southwest corner of section 13., T. 20 N., R. 19 E.; USGS Reno 7.5 minute topographic quadrangle; latitude 39 degrees 35 minutes 57 seconds N and longitude 119 degrees 48 minutes 18 seconds W; WGS84 Decimal Degrees 39.5991667 latitude, -119.8050000 longitude.
RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring, dry in summer and fall; aridic soil moisture regime that borders on xeric.
Mean annual soil temperature: 8 to 12 degrees C.
Depth to bedrock: 50 to 100 cm to a lithic contact. The bedrock is weathered and fractured in most pedons but it cannot be dug with hand tools.
Reaction: Moderately acid through slightly alkaline.
Particle-size control section - Clay content: 35 to 50 percent.
Rock fragments: 5 to 35 percent, mainly gravel. Lithology of fragments are volcanic rocks such as andesite and basalt.
A horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3, dry or moist.
Structure: Granular, platy, subangular blocky, or massive.
Consistence: Slightly sticky or moderately sticky and slightly plastic or slightly plastic, wet.
Bt horizons
Hue: 10YR or 7.5YR.
Value: 4 through 6 dry, 3 or 4 moist.
Chroma: 2 through 4, dry or moist.
Texture: Clay, clay loam, or sandy clay
Structure: Angular blocky, subangular blocky, or prismatic.
Consistence: Moderately plastic or very plastic, wet.
COMPETING SERIES: These are the
Buncelvoir,
Diaz,
Farmell,
Glasgow,
Lanktree,
Milkiway,
Risley,
Schamp, and
Trunk series.
Buncelvoir,
Farmell,
Lanktree,
Milkiway, and
Schamp soils are very deep.
Diaz soils have transitional BAt horizons in the upper part of the argillic horizon and are effervescent in the argillic horizon.
Glasgow soils have A horizons formed in a mantle of loess high in volcanic ash and have identifiable secondary carbonates in the lower part of the argillic horizon.
Risley soils are moderately deep to paralithic contacts.
Trunk soils have identifiable secondary carbonates in the lower part of the argillic horizon.
GEOGRAPHIC SETTING: Oppio soils are on mountains, hills, and plateaus. They typically occur on footslope or backslope positions. These soils formed in residuum derived from andesite and other basic volcanic rocks. Slopes are 2 to 50 percent. Elevations range from 1,310 to 1,980 meters. The mean annual precipitation is 200 to 300 mm, the mean annual temperature is 8 to 10 degrees C, and the frost-free period is 80 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Greenbrae,
Mizel,
Northmore,
Surgem,
Wedekind and
Yuko soils and the competing
Risley soil. Greenbrae soils are very deep and fine-loamy. Mizel soils are less than 25 cm deep and loamy-skeletal. Northmore soils are very deep. Surgem soils are clayey-skeletal and are underlain by granodiorite. Wedekind soils have 25 to 50 cm thick sandy clay loam argillic horizons. Yuko soils have silty clay loam argillic horizons.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; high surface runoff; moderately low saturated hydraulic conductivity.
USE AND VEGETATION: Oppio soils are used for rangeland, recreation, urban development, and wildlife habitat. The native vegetation is low sagebrush, Thurber's needlegrass, Sandberg's bluegrass, low rabbitbrush, and bottlebrush squirreltail.
DISTRIBUTION AND EXTENT: Western Nevada. These soils are moderately extensive. The series concept and main acreage is in MLRA 26, while other acreage occurs in MLRAs 23 and 27.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Washoe County, Nevada, 1975.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 8 cm (A horizon).
Argillic horizon - The zone from 8 to 53 cm (Bt1, Bt2, and Bt3 horizons).
Lithic contact - The boundary at 53 cm to underlying hard bedrock (R layer).
Particle-size control section - The zone from 8 to 53 cm (Bt1, Bt2, and Bt3 horizons).
ADDITIONAL DATA: User Pedon ID: 2006NV031003.
National Cooperative Soil Survey
U.S.A.