LOCATION SHADOVAL                ID

Established Series
Rev. MEJ/ALH/RWL
07/2012

SHADOVAL SERIES

The Shadoval series consists of moderately deep, well drained soils with very slow permeability that formed in colluvium and residuum from lacustrine deposits. Shadoval soils are on foothills and have slopes of 4 to 50 percent. The average annual precipitation is about 13 inches and the average annual temperature is about 51 degrees F.

TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Natrixerolls

TYPICAL PEDON: Shadoval silt loam -- on a 11 percent convex west-northwest facing slope at 2,940 feet elevation in rangeland. When described on August 9, 1995, the soil was dry throughout. (Colors are for dry soil unless otherwise noted.)

A--0 to 2 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak thin platy structure parting to moderate fine granular; soft, very friable, slightly sticky and slightly plastic; common very fine and fine, few medium roots; many very fine and fine tubular pores; neutral (pH 6.8); clear smooth boundary. (2 to 8 inches thick)

BA--2 to 4 inches; grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate thin platy structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine and fine tubular pores; about 10 percent of faces of peds covered with uncoated silt grains; neutral (pH 7.2); abrupt wavy boundary. (2 to 7 inches thick)

Btn--4 to 10 inches; dark grayish brown (10YR 4/2) clay, very dark brown (10YR 2/2) moist; strong medium and coarse prismatic structure; extremely hard, firm, very sticky and very plastic; few very fine, fine and medium roots; few very fine and fine tubular pores; common prominent clay films on faces of peds and in pores; cracks 2 to 10 mm wide; ESP 9, SAR 8; moderately alkaline (pH 8.0); clear smooth boundary. (3 to 10 inches thick)

Btkn--10 to 15 inches; yellowish brown (10YR 5/4) silty clay loam, dark yellowish brown (10YR 3/4) moist; strong fine and medium prismatic structure parting to strong medium subangular blocky; very hard, friable, very sticky and very plastic; common very fine, fine and medium roots; few very fine and fine tubular pores; common distinct clay films on faces of peds and in pores; slightly effervescent; about 5 percent calcium carbonate; segregated as coats on faces of peds; ESP 15, SAR 11; slightly saline; moderately alkaline (pH 8.2); clear wavy boundary. (3 to 12 inches thick)

Bkn--15 to 20 inches; pale brown (10YR 6/3) silty clay, brown (10YR 4/3) moist; weak fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine and fine tubular pores; strongly effervescent; about 10 percent disseminated calcium carbonate; ESP 20, SAR 14, moderately saline; moderately alkaline (pH 8.0); gradual wavy boundary. (3 to 12 inches thick)

Bkny1--20 to 32 inches; very pale brown (10YR 8/2) silt loam, light brownish gray (10YR 6/2) moist; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine and fine tubular pores; strongly effervescent; about 10 percent disseminated calcium carbonate; ESP 22, SAR 14; about 4 percent disseminated gypsum; moderately saline; moderately alkaline (pH 8.0); clear wavy boundary. (5 to 15 inches thick)

Bkny2--32 to 39 inches; very pale brown (10YR 8/3) silt loam, pale brown (10YR 6/3) moist; weak fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine and fine tubular pores; strongly effervescent; about 5 percent disseminated calcium carbonate; ESP 30, SAR 15; about 9 percent gypsum segregated as coats on faces of peds; moderately saline; moderately alkaline (pH 8.0); abrupt wavy boundary. (0 to 9 inches thick)

Crky--39 to 49 inches; very pale brown (10YR 8/3) stratified silty lacustrine deposits with discontinuous, very thin (less than 1mm) calcium carbonate and gypsum coats on horizontal and vertical sediment planes.

TYPE LOCATION: Ada County, Idaho; about 3.5 miles east and 4 miles north of Eagle; 1,100 feet south and 1,200 feet east of the northwest corner of section 25, T. 5 N., R. 1 E.; USGS Eagle Quadrangle; (Latitude - 43 degrees, 50 minutes, 41 seconds N. and Longitude - 116 degrees, 17 minutes, 11 seconds W.)

RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon - 10 to 15 inches
Depth to abrupt texture change - 4 to 12 inches
Depth to calcium carbonate - 8 to 23 inches
Depth to paralithic contact - 20 to 40 inches
Average annual soil temperature - 52 to 54 degrees F.
Moisture control section - moist less than 90 consecutive day when the soil temperature is greater than 47 degrees F.

A (or E) horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Clay content - 15 to 25 percent
Rock fragments - 0 to 5 percent gravel

BA horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Texture - SICL, SIL or CL
Clay content - 20 to 35 percent
Rock fragments - 0 to 5 percent gravel
Reaction - neutral or slightly alkaline

Btn horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Texture - SICL, SIC or C
Clay content - 35 to 55 percent
Rock fragments - 0 to 5 percent gravel
Cracks - 0 to 15 mm wide
Reaction - slightly alkaline or moderately alkaline
ESP - 5 to 10 percent
SAR - 5 to 10 percent

Btkn horizon
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 3 or 4 dry or moist
Texture - SICL or SIC
Clay content - 30 to 50 percent
Rock fragments - 0 to 5 percent gravel
Cracks - 0 to 10 mm wide
Calcium carbonate equivalent - 1 to 10 percent
ESP - 15 to 17 percent
SAR - 10 to 15 percent

Bkn horizon
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 2 or 3 dry or moist
Texture - SICL or SIL
Clay content - 20 to 30 percent
Rock fragments - 0 to 5 percent gravel
Calcium carbonate equivalent - 3 to 15 percent
Salinity - slightly or moderately saline
ESP - 15 to 20 percent
SAR - 10 to 15 percent

Bkyn horizon
Value - 6 through 8 dry, 4 through 6 moist
Chroma - 2 or 3 dry or moist
Clay content - 10 to 27 percent
Rock fragments - 0 to 5 percent gravel
Calcium carbonate equivalent - 3 to 15 percent
Calcium sulfate equivalent - 3 to 10 percent
Salinity - slightly or moderately saline
ESP - 15 to 30 percent
SAR - 12 to 15 percent

COMPETING SERIES: These are the Pawtoot (T) and Susanville series. Pawtoot soils are very deep to a paralithic contact. Susanville soils are very deep, dry for more than 160 consecutive days following the summer solstice, have carbonates at 26 to 44 inches, and lack a gypsic horizon.

GEOGRAPHIC SETTING: Shadoval soils are on hill backslopes and summits and have slopes of 4 to 50 percent. The soils formed in colluvium and residuum from lacustrine deposits. The elevation ranges from 2,700 to 3,300 feet. The average annual precipitation is 12 to 15 inches and average annual temperature is 50 to 52 degrees F. The frost-free period is 140 to 155 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Polecat and competing Pawtoot soils. Polecat soils are deep to a paralithic contact, are fine-silty and occur on the same landform as the Shadovalsoils.

DRAINAGE AND PERMEABILITY: Well drained; medium to very rapid runoff; very slow permeability.

USE AND VEGETATION: Shadoval soils are used mainly for rangeland. Natural vegetation is basin big sagebrush and bluebunch wheatgrass.

DISTRIBUTION AND EXTENT: Ada County, Idaho. MLRA 10. The soils are of limited extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Ada County, Idaho, 2012.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - zone from the surface to 10 inches (A, BA and Bt horizons)
Abrupt textural change - at 4 inches with a 21 percent clay increase within 1 inch (upper boundary of Bt horizon)
Natric horizon - zone from 4 to 15 inches (Btn and Btkn horizons)
Gypsic horizon - zone from 32 to 39 inches (Bkny2 horizon)
Paralithic contact - at 39 inches (Crky horizon)
Linear extensibility - 6.0 cm or more from the soil surface to the paralithic contact
Particle-size control section - zone from 4 to 15 inches (Bt and Btk horizons)
Soil moisture regime - aridic bordering xeric
These soils are drier than other Xerolls in the region under similar precipitation due to early runoff and extended period of high evapotranspiration.

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National Cooperative Soil Survey
U.S.A.