LOCATION FORVIC ID+NVEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Typic Durixerolls
TYPICAL PEDON: Forvic silty clay loam - on a west facing slope of 5 percent under rangeland vegetation at 6,100 feet elevation. When described on September 27, 1979, the soil profile was slightly moist throughout. (Colors are for dry soil unless otherwise noted.)
A--0 to 7 inches; dark grayish brown (10YR 4/2) silty clay loam, black (10YR 2/1) moist; moderate medium platy structure; soft, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine and fine tubular pores; 10 percent gravel; slightly acid (pH 6.5); clear smooth boundary. (5 to 14 inches thick)
Bt1--7 to 12 inches; brown (10YR 4/3) clay, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; hard, firm, sticky and plastic; many very fine and fine roots; common very fine and fine tubular pores; common moderately thick clay films on faces of peds and in pores; 10 percent gravel; slightly acid (pH 6.5); gradual wavy boundary. (4 to 14 inches thick)
Bt2--12 to 21 inches; dark brown (10YR 3/3) gravelly clay, dark brown (10YR 3/3) moist; strong coarse prismatic structure parting to strong medium angular blocky; extremely hard, extremely firm, very sticky and very plastic; common very fine and fine roots; few very fine and fine tubular pores; many thick clay films on faces of peds and in pores; 15 percent gravel; slightly acid (pH 6.5); abrupt smooth boundary. (0 to 14 inches thick)
Bt3--21 to 30 inches; light brown (7.5YR 6/4) very gravelly sandy clay, brown (7.5YR 4/4) moist; moderate medium angular blocky structure; hard, firm, sticky and plastic; common very fine and fine roots; few very fine and fine tubular pores; many moderately thick clay films on faces of peds and in pores; 35 percent gravel; slightly acid (pH 6.5); abrupt smooth boundary. (2 to 10 inches thick)
Bkqm--30 to 35 inches; white (10YR 8/2) duripan, very pale brown (10YR 7/3) moist; massive; extremely hard, extremely firm; few very fine and fine roots in fractures of the duripan; many continuous silica laminations running between cemented gravel; fractures are 1/4-inch wide and are 10 inches apart; violent effervescent; abrupt smooth boundary. (3 to 11 inches thick)
2Cr--35 inches; very pale brown (10YR 7/4) welded ash, dark yellowish brown (10YR 4/6) moist; moderate medium platy structure; top of plates slightly effervescent.
TYPE LOCATION: Twin Falls County, Idaho; about 19 miles southeast of Rogerson, Idaho; in the northeast 1/4, southeast 1/4, southeast 1/4, section 21, T. 16 S., R. 18 E.
RANGE IN CHARACTERISTICS:
Average summer soil temperature - 60 to 62 degrees F.
Depth to duripan - 20 to 40 inches
Mollic epipedon thickness - 20 to 30 inches
Clay content in control section average - 50 to 59 percent
Average annual soil temperature - 43 to 45 degrees F.
Depth to welded ash - 24 to 50 inches
Reaction - slightly acid or neutral
A Horizon
Color value, dry - 3 or 4
Chroma - 1 or 2 dry or moist
Gravel - 5 to 25 percent
Structure
Type - granular, subangular blocky, or platy
Bt Horizons
Color hue - 7.5YR or 10YR
Value, dry - 2 through 6
Value, moist - 2 or 4
Chroma - 2 through 4 dry or moist
Texture - C, GR-C, GRV-SC, or GRV-C
Structure
Type - subangular blocky, angular blocky, or prismatic
Clay films
Frequency - common or many
Thickness - moderately thick or thick
Morphology - faces of peds and in pores
Gravel - 10 to 55 percent
Gravel-control section average - less than 35 percent
Bkqm Horizon
Distance between fractures - 8 to 12 inches
COMPETING SERIES: These are the Budlewis (T), Hatpeak (T), Manard, Oshone (T), Peevywell (T), and Tanner (T) series. Budlewis, Manard, and Tanner soils have 35 to 50 percent clay in the Bt horizon, and are not pachic. Hatpeak and Peevywell soils are more than 60 inches deep to bedrock and are not pachic. Oshone soils have a mollic epipedon that is less than 20 inches thick.
GEOGRAPHIC SETTING: Forvic soils are on terraces, summits, and hillsides. The slope ranges from 2 to 15 percent. The soils formed in old alluvium and colluvium from welded tuff. Elevations are 5,800 to 6,600 feet. The average annual precipitation ranges from 14 to 18 inches, and the average annual temperature is 41 to 43 degrees F. The frost free season is 80 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Amboat, Aninto, Brose, and Oshone soils. Amboat and Brose soils occur on summits. Amboat soils are clayey-skeletal. Brose soils are shallow to bedrock. Aninto soils occur on terrace sideslopes, are deep, and clayey-skeletal. Oshone soils occur on lower terraces, and have a thinner A horizon.
DRAINAGE AND PERMEABILITY: Well drained, medium runoff; slow permeability.
USE AND VEGETATION: Forvic soils are used for rangeland. Native vegetation is Idaho fescue, bluebunch wheatgrass, Nevada bluegrass, and mountain big sagebrush.
DISTRIBUTION AND EXTENT: Forvic soils are of small extent in south central Idaho and northeastern Nevada.
MLRA OFFICE RESPONSIBLE: Reno, Nevada
SERIES ESTABLISHED: Elko County, Nevada, Northeast Part 1986.
REMARKS: Clay percent by dyrometer: 0-7inches - 40 percent; 7-12 inches - 48 percent; 12-21 inches - 64 percent. Base saturation: 0-7 inches - 76 percent; 7-12 inches - 75 percent; 12-21 inches - 80 percent.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 21 inches (A, Bt1, and Bt2 horizons)
Argillic horizon - 7 to 27 inches (Bt1, Bt2, and part of the Bt3 horizon)
Indurated duripan - 30 to 35 inches (Bkqm horizon)