LOCATION OCUD NV
Established Series
Rev. EWB-TM-JVC-JBF
11/2016
OCUD SERIES
The Ocud series consists of very shallow and shallow, well drained soils that formed in residuum and colluvium derived from volcanic rocks. Ocud soils are on mountains. Slopes are 15 to 50 percent. The mean annual precipitation is about 300 mm and the mean annual temperature is about 9 degrees C.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Aridic Lithic Argixerolls
TYPICAL PEDON: Ocud extremely gravelly sandy loam--forestland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with about 75 percent gravel, 10 percent cobbles, and less than 1 percent stones.
A1--0 to 13 cm; grayish brown (10YR 5/2) extremely gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; few very fine roots; many fine and medium interstitial pores; 85 percent gravel and 5 percent cobbles; slightly acid (pH 6.2); clear wavy boundary. (5 to 13 cm thick)
A2--13 to 25 cm; brown (10YR 5/3) extremely gravelly loam, dark brown (10YR 3/3) moist; weak fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; common very fine and fine roots; common very fine and fine interstitial and common very fine tubular pores; 60 percent gravel; slightly acid (pH 6.5); clear wavy boundary. (5 to 13 cm thick)
Bt--25 to 33 cm; pale brown (10YR 6/3) extremely gravelly sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; very hard, friable, slightly sticky and slightly plastic; few very fine through coarse roots; common very fine tubular and interstitial pores; 60 percent gravel; common faint clay films on faces of peds; slightly acid (pH 6.2); clear irregular boundary. (7 to 15 cm thick)
R--33 cm; hard fractured altered volcanic rock; fractured in the upper 10 cm.
TYPE LOCATION: Douglas County, Nevada; in the southern Pine Nut Mountains about 1.7 miles southeast of Carters Station; about 700 feet north and 650 feet west of the southeast corner of section 10, T. 11 N., R. 21 E.; USGS Double Spring 7.5 minute topographic quadrangle; latitude 38 degrees 49 minutes 33 seconds N and longitude 119 degrees 36 minutes 26 seconds W; WGS84 Decimal Degrees 38.8258333 latitude, -119.6072222 longitude.
RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring, dry from July through October; aridic soil moisture regime that borders on xeric.
Mean annual soil temperature: 8 to 12 degrees C.
Mollic epipedon thickness: 18 to 30 cm; includes the Bt horizon in some pedons.
Depth to bedrock: 17 to 36 cm to a lithic contact.
Reaction: Slightly acid or neutral.
Particle-size control section - Clay content: Averages 15 to 25 percent. Rock fragments: 60 to 80 percent, mainly gravel. Lithology of fragments is volcanic rocks such as rhyolite or andesite.
A horizons
Chroma: 2 or 3, dry or moist.
Organic matter content: 1 to 3 percent.
Bt horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3, dry or moist.
Texture: Extremely gravelly sandy loam or extremely gravelly sandy clay loam.
Clay content: 18 to 27 percent.
Rock fragments: 60 to 80 percent.
Consistence: Hard or very hard dry, very friable or friable moist.
Organic matter content: 1 or 2 percent.
COMPETING SERIES: These are the
Argabak,
Bellehelen,
Brier,
Duco,
Horseflat,
Nuhelen,
Orhood,
Reywat, and Upatad.
Argabak soils have mollic epipedons that are 13 to 18 cm thick.
Bellehelen,
Brier and
Nuhelen soils are moist for 10 to 20 days during the summer due to convection storms and have 35 to 60 percent rock fragments in the particle-size control section.
Duco soils have 27 to 35 percent clay in the particle-size control section.
Horseflat soils have mollic epipedons 30 to 43 cm thick and have silica coating the lithic contact.
Orhood soils have hue of 7.5YR.
Reywat soils have accumulation of identifiable secondary carbonates above the bedrock contact.
Upatad soils have 35 to 60 percent rock fragments in the particle-size control section, have horizons with identifiable secondary carbonates, and have lithic contacts at depths of 36 to 50 cm.
GEOGRAPHIC SETTING: Ocud soils are on mountains. These soils formed in residuum and colluvium derived from volcanic rocks. Slopes are 15 to 50 percent. Elevations range from 1,750 to 2,100 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 250 to 375 mm, mean annual temperature is 8 to 10 degrees C, and the frost-free period is 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing
Duco soil and the
Nosrac soil. Nosrac soils are very deep.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; very high surface runoff; moderately high saturated hydraulic conductivity.
USE AND VEGETATION: Ocud soils are used for forestland and wildlife habitat. The present vegetation is mainly a forest canopy of singleleaf pinyon with an understory of mountain big sagebrush, green ephedra, antelope bitterbrush, and desert needlegrass.
DISTRIBUTION AND EXTENT: Western Nevada. These soils are not extensive. MLRA 26.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Douglas County, Nevada, 2012. The name is coined.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 25 cm (A1 and A2 horizons).
Argillic horizon - The zone from 25 to 33 cm (Bt horizon).
Lithic contact - The boundary at 33 cm to hard bedrock (R layer).
Particle-size control section - The zone from the soil surface to 33 cm (A1, A2, and Bt horizons).
Classification was updated to 11th edition on 07/2011 changed Lithic Argixerolls to Aridic Lithic Argixerolls.
ADDITIONAL DATA: User Pedon ID: 2006NV005019.
National Cooperative Soil Survey
U.S.A.