LOCATION BUCAN                   NV

Established Series
Rev. CEJ/RLB/JBF
11/2016

BUCAN SERIES

The Bucan series consist of deep, well drained soils formed in loess high in volcanic ash over residuum derived from volcanic rocks and tuff. The Bucan soils are on hill and mountain side slopes. Slopes are 15 to 50 percent. The mean annual precipitation is about 230 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Fine, smectitic, frigid Xeric Haplargids

TYPICAL PEDON: Bucan loam--rangeland. (Colors for dry conditions unless otherwise noted.)

A1--0 to 10 cm; light brownish gray (10YR 6/2) loam, very dark grayish brown (10YR 3/2) moist; weak thin platy structure; slightly hard, very friable, slightly sticky and slightly plastic; many fine and very fine, and few medium roots; common very fine tubular, and many fine interstitial pores; neutral (pH 6.8); clear wavy boundary. (5 to 15 cm thick)

A2--10 to 18 cm; grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; slightly hard, very friable, sticky and plastic; common fine and very fine, and few medium roots; common very fine tubular, and many fine interstitial pores; neutral (pH 6.8); abrupt smooth boundary. (0 to 18 cm thick)

Bt1--18 to 28 cm; grayish brown (10YR 5/2) cobbly clay, dark grayish brown (10YR 4/2) moist; weak fine subangular blocky structure; hard, friable, very sticky and very plastic; common fine and very fine, and few medium roots; common fine and very fine tubular pores; common distinct clay films in pores and on faces of ped; 5 percent gravel, 10 percent cobbles; neutral (pH 6.8); abrupt smooth boundary. (8 to 25 cm thick)

Bt2--28 to 64 cm; brown (10YR 5/3) clay, brown (10YR 4/3) moist; strong fine and medium prismatic structure; very hard, firm, very sticky and very plastic; common very fine, few medium, and very few coarse roots; common fine and very fine tubular pores; continuous prominent clay films on faces of ped and in pores, and many pressure faces on vertical faces of peds; 5 percent cobbles; slightly effervescent on underside of cobbles; neutral (pH 7.0); clear wavy boundary. (18 to 38 cm thick)

2Btk1--64 to 89 cm; yellowish brown (10YR 5/4) gravelly clay, brown (10YR 4/3) moist; moderate medium and fine angular blocky structure; very hard, firm, very sticky and very plastic; few very fine roots; common fine and very fine tubular pores; many distinct clay films in pores and on peds; 25 percent gravel, 5 percent cobbles; common medium and coarse white (10YR 8/1) carbonate segregations on ped faces; matrix is noneffervescent but is violently effervescent in spots and on undersides of gravel and cobbles; strongly alkaline (pH 8.5); clear wavy boundary. (20 to 46 cm thick)

2Btk2--89 to 127 cm; pale brown (10YR 6/3) gravelly clay, brown (10YR 4/3) moist; massive; hard, friable, sticky and plastic; few very fine tubular, and common fine interstitial pores; common distinct clay films in pores; 25 percent gravel, 5 percent cobbles; many medium and coarse prominent very pale brown (10YR 8/2) carbonate segregations; violently effervescent; strongly alkaline (pH 8.6); abrupt wavy boundary.

2R--127 cm; unweathered bedrock.

TYPE LOCATION: Lander County, Nevada; about 10 miles southeast of Beowawe, Nevada; approximately 2,150 feet west and 500 feet south of the northeast corner of section 34, T. 31 N., R. 47 E., Mount Diablo base line and meridian; USGS Mule Canyon 7.5 minute topographic quadrangle; latitude 40 degrees 31 minutes 16 seconds N and longitude 116 degrees 39 minutes 39 seconds W; WGS84 Decimal Degrees 40.5211111 latitude, -116.6608333 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry, moist in some part from late October through early June; aridic soil moisture regime bordering on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Depth to segregated carbonates: 38 to 76 cm.
Depth to bedrock: 100 to 150 cm.

Particle-size control section - Clay content: 40 to 60 percent.
Rock fragments: Average 0 to 15 percent, when mixed.

A horizon
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 or 3.
Other features: When mixed to a depth of 18 cm, the value dry is 6 or the thickness of the epipedon is less than one-third the soil thickness.

Bt horizons
Value: 4 through 6 dry, 3 through 5 moist.
Chroma: 2 through 4.
Texture: Clay or cobbly clay.
Clay content: 45 to 60 percent.
Rock fragments: 0 to 20 percent, but average less than 15 percent.
Structure: Weak to strong fine or medium subangular or angular blocky in the Bt1 horizon and moderate or strong fine or medium prismatic in the Bt2 horizon.
Reaction: Neutral or slightly alkaline.

Btk horizons
Value: 4 through 6 dry, 4 or 5 moist.
Chroma: 3 through 6.
Texture: Clay loam or clay.
Texture modifiers: Gravelly or cobbly.
Clay content: 35 to 45 percent.
Rock fragments: 15 to 35 percent, mainly gravel with cobbles common in some subhorizons.
Structure: Medium and fine angular blocky, prismatic or it is massive.
Reaction: Slightly alkaline through strongly alkaline.

COMPETING SERIES: These are the Deseed and Fortank series.

Deseed and Fortank soils are moderately deep to bedrock.

GEOGRAPHIC SETTING: Bucan soils are on hill and mountain side slopes. These soils formed in loess high in volcanic ash over residuum and colluvium derived from extrusive volcanic rocks and tuff. Slopes are 15 to 50 percent. Elevations are 1,520 to 2,440 meters. The climate is cool, semiarid with hot, dry summers and cool, moist winters. The mean annual precipitation is 200 to 250 mm; mean annual temperature is 6 to 7 degrees C, and the frost-free season is 80 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Creva, Havingdon, Humdun, Softscrabble, and Walti soils. Creva soils are shallow to bedrock and are loamy-skeletal. Havingdon soils are moderately deep and clayey-skeletal. Humdun soils are very deep and coarse-loamy. Softscrabble soils are loamy-skeletal and have thick mollic epipedons. Walti soils are moderately deep and have mollic epipedons.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; medium or rapid runoff; moderately low saturated hydraulic conductivity.

USE AND VEGETATION: Rangeland and wildlife habitat. The present vegetation is mainly of big sagebrush, Douglas rabbitbrush, littleleaf horsebrush, Thurber needlegrass, bluebunch wheatgrass and cheatgrass.

DISTRIBUTION AND EXTENT: North-central Nevada. These soils are moderately extensive. MLRA 24 and 25.

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

SERIES ESTABLISHED: Lander County, (Tuscarora Mountain Area), Nevada, 1979.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (the A1 and A2 horizons).
Xeric Intergrades - Meets organic carbon requirement for xeric.
Argillic horizon - The zone from 18 to 127 cm (the Bt1, Bt2, 2Btk1, and 2Btk2 horizons).
Particle-size control section - The zone from 18 to 68 cm (the Bt1 and Bt2 horizons and a portion of the 2Btk1 horizon).

---

National Cooperative Soil Survey
U.S.A.