LOCATION BLACKLEG                ID+NV

Established Series
Rev. JSR/ALH/CLM/JBF
09/2018

BLACKLEG SERIES

The Blackleg series consists of moderately deep to a duripan, well drained soils that formed in alluvium and colluvium derived from extrusive rocks and volcanic ash. Blackleg soils are on outwash and fan terraces with slopes of 2 to 30 percent. The average annual precipitation is about 380 mm and the average annual temperature is about 5 degrees C.

TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Typic Durixerolls

TYPICAL PEDON: Blackleg loam -- on a west-facing slightly concave slope of 7 percent, in native rangeland at 1,635 meters elevation. The surface has about 3 percent stone cover. (When described on August 22, 1979, the soil was slightly moist throughout. Colors are for air dry soil unless otherwise stated.)

A--0 to 15 cm; brown (10YR 5/3) loam, very dark brown (10YR 2/2) moist; weak thin platy structure parting to moderate fine granular; slightly hard, very friable, nonsticky and nonplastic; many fine and very fine, common medium and coarse roots; many fine and very fine interstitial pores; 5 percent gravel, 5 percent cobbles, 1 percent stones; neutral (pH 6.7); clear smooth boundary. (10 to 18 cm thick)

BA--15 to 33 cm; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, very friable; slightly sticky and slightly plastic; common fine, very fine, medium and coarse roots; common fine and very fine tubular pores; 5 percent gravel, 5 percent cobbles; slightly acid (pH 6.4); clear wavy boundary. (0 to 30 cm thick)

Bt1--33 to 58 cm; brown (10YR 5/3) cobbly clay loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure parting to strong fine granular; hard, firm, moderately sticky and moderately plastic; common very fine, fine, medium and coarse roots; common fine tubular pores; many distinct clay films on faces of peds; 10 percent gravel, 20 percent cobbles; slightly acid (pH 6.5); abrupt wavy boundary. (8 to 38 cm thick)

Bt2--58 to 74 cm; yellowish brown (10YR 5/4) very cobbly clay, brown (7.5YR 4/4) moist; strong medium and coarse prismatic structure parting to strong, medium angular blocky; very hard, very firm, very sticky and very plastic; common fine and medium roots; common fine tubular pores; continuous prominent clay films on faces of peds; 10 percent gravel, 25 percent cobbles; neutral (pH 6.6); clear wavy boundary. (15 to 38 cm thick)

Btq--74 to 91 cm; yellowish brown (10YR 5/4) very cobbly clay, brown (10YR 4/3) moist; strong fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; common fine tubular pores; common distinct clay films on faces of peds; 20 percent gravel, 30 percent cobbles; thin pendants of silica on undersides of rock fragments; neutral (pH 6.8); clear wavy boundary. (9 to 36 cm thick)

Bqm--91 to 127 cm; light yellowish brown (10YR 6/4) continuous, indurated duripan, strong brown (7.5YR 4/6) moist; massive; extremely hard, brittle; neutral (pH 6.7).

TYPE LOCATION: Owyhee County, Idaho; about 2 1/2 miles southeast of the northeast corner of Duck Valley Indian Reservation; 2,400 feet south and 400 feet west of the northeast corner of section 11, T. 15 S., R. 4 E.; USGS Buckhorn 7.5 minute topographic quadrangle; latitude 42 degrees 8 minutes 11 seconds N and longitude 115 degrees 56 minutes 39 seconds W; WGS84 Decimal Degrees 42.1363889 latitude, -115.9441667 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring; dry from July through October; xeric soil moisture regime.
Mean annual soil temperature: 4 to 8 degrees C.
Mean summer soil temperature: 15 to 19 degrees C.
Mollic epipedon thickness: 18 to 40 cm
Depth to duripan: 50 to 100 cm

Particle-size control section - Clay content: 35 to 50 percent.
Rock fragments: Average 35 to 75 percent mainly gravel.

A horizon
Hue: 7.5YR or 10YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3 dry or moist.

Bt1 horizon
Hue: 7.5YR or 10YR.
Value: 4 through 6 dry, 3 or 4 moist.
Chroma: 2 through 4 dry or moist.
Texture: Cobbly clay loam, gravely clay loam, cobbly clay, or silty clay loam.
Reaction (pH): Slightly acid through slightly alkaline.

Bt2 and Btq horizons
Hue: 7.5YR or 10YR.
Value: 4 through 6 dry, 3 or 4 moist.
Chroma: 2 through 4 dry or moist.
Texture: Very cobbly clay loam, very gravelly clay loam, very cobbly clay, extremely cobbly clay, or very gravelly clay.
Reaction (pH): Slightly acid through slightly alkaline.

Bqm horizon
Structure: Massive or platy.
Effervescence: Noneffervescent through strongly effervescent.

COMPETING SERIES: There are no other series in the family.

GEOGRAPHIC SETTING: Blackleg soils are on escarpments of tablelands and summits, backslopes, and footslopes of outwash and fan terraces. Elevations range from 1,525 to 2,170 meters. Slopes range from 2 to 30 percent. The soils formed in alluvium and colluviums derived from extrusive rocks and volcanic ash. The climate is cool and moist in the winter and warm and dry in the summer. Average annual precipitation is 300 to 430 mm. Average annual temperature is 3 to 7 degrees C. Frost-free period is 50 to 95 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Barkley, Hatpeak, Thacker, Threek, Wickahoney, and Yatahoney soils. Wickahoney soils have bedrock within 50 cm of the surface. Barkley, Hatpeak, Thacker, and Yatahoney soils have less than 35 percent coarse fragments in the textural control section. Threek and Wickahoney soils lack a duripan.

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

USE AND VEGETATION: Blackleg soils are used mainly for rangeland and wildlife habitat. The dominant natural vegetation is low sagebrush, Idaho fescue, antelope bitterbrush, bluebunch wheatgrass, and less commonly mountain big sagebrush or basin big sagebrush.

DISTRIBUTION AND EXTENT: Southwestern Idaho and north-central Nevada. Blackleg soils are of moderate extent. MLRA 25.

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

SERIES ESTABLISHED: Owyhee County, Idaho; Duck Valley Indian Reservation, Idaho-Nevada, 1984.

REMARKS: Diagnostic horizons and other features recognized in this pedon:
Mollic epipedon - The zone from the surface to 33 cm (A and BA horizons).
Argillic horizon and particle-size control section - The zone from 33 to 91 cm (Bt1, Bt2, and Btq horizons).
Duripan - The zone from 91 to 127 cm (Bqm horizon).

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National Cooperative Soil Survey
U.S.A.