LOCATION IBOLA                   ID

Established Series
Rev. DA/CLM
01/2019

IBOLA SERIES

The Ibola series consists of moderately deep to a duripan, well drained soils, with moderately slow permeability that formed in mixed alluvium from welded tuff and volcanic ash. They are on terraces. Slopes range from 2 to 6 percent. The average annual precipitation is about 360 mm, and the average annual temperature is about 6.1 degrees C.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Typic Durixerolls

TYPICAL PEDON: Ibola loam -- on a northwest facing slope of 4 percent under rangeland vegetation at 1,755 meters elevation. (Colors are for air dry soil unless otherwise stated.) When described on August 4, 1982, the soils profile was dry.

A--0 to 10 cm; brown (10YR 4/3) loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine, fine and medium roots; many very fine and fine tubular pores; 5 percent gravel; slightly acid (pH 6.2); abrupt smooth boundary. (8 to 20 cm thick)

Bt1--10 to 20 cm; dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine, fine and medium roots; many very fine and fine tubular pores; few faint clay films on faces of peds and in pores; 5 percent gravel; moderately acid (pH 6.0); clear smooth boundary. (10 to 25 cm thick)

Bt2--20 to 46 cm; grayish brown (10YR 5/2) clay loam, dark brown (7.5YR 3/2) moist; strong medium angular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine and fine roots; common very fine and fine tubular pores; common distinct clay films on faces of peds and in pores; moderately acid (pH 5.9); clear smooth boundary. (23 to 36 cm thick)

Bt3--46 to 69 cm; light brown (7.5YR 6/4) gravelly loam, dark brown (7.5YR 4/4) moist; moderate medium subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine and fine roots; common very fine and fine tubular pores; few faint clay films on faces of peds and in pores; 15 percent gravel; moderately acid (pH 6.0); abrupt smooth boundary. (10 to 51 cm thick)

Bqm--69 to 71 cm; white (10YR 8/2) indurated duripan, light gray (10YR 7/2) moist; massive; continuous silica cap over a non-calcareous matrix; abrupt smooth boundary. (2 to 10 cm thick)

Crk--71 to 163 cm; light brown (7.5YR 6/4) semi-consolidated volcanic ash, brown (7.5YR 4/4) moist; massive; non-calcareous matrix with carbonate masses intermixed.

TYPE LOCATION: Twin Falls County, Idaho; about 23 miles southwest of Rogerson, Idaho; about 780 feet north and 180 feet east of the southwest corner of section 11, T. 15 S., R. 12 E.; USGS Grassy Hills 7.5 minute topographic quadrangle; latitude 42 degrees 07 minutes 52 seconds N and longitude 115 degrees 01 minutes 42 seconds W; WGS84 Decimal Degrees 42.1311111 latitude, -115.0283333 longitude.

RANGE IN CHARACTERISTICS:
Soil Moisture: This soil is usually moist, but is dry for 45 to 70 consecutive days during the late summer and autumn. Typic xeric moisture regime.
Mollic epipedon thickness - 28 to 48 cm.
Depth to duripan - 50 to 100 cm.
Depth to paralithic contact - 51 to 100 cm
Average annual soil temperature - 6.1 to 7.2 degrees C.
Thickness of duripan - 1 to 4 inches

A horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Gravel - 0 to 10 percent
Reaction - slightly acid or neutral

Bt horizons
Hue - 10YR or 7.5YR
Value - 4 through 6 dry, 2 through 4 moist
Chroma - 2 through 4 dry or moist
Texture - L, CL, GR-L, GR-CL
Clay content - 24 to 34 percent
Gravel - 0 to 25 percent
Cobbles - 0 to 5 percent
Reaction - moderately acid through neutral

COMPETING SERIES: These are the Chayson and Northcastle series. Chayson soils have secondary carbonates. Northcastle soils have a duripan that is 13 to more than 66 cm thick.

GEOGRAPHIC SETTING: The Ibola soils are on terraces. The slopes range from 2 to 6 percent. The soils formed in mixed alluvium from welded tuff and volcanic ash. Elevations are 1,680 to 1,830 meters. The average annual precipitation is 300 to 380 mm. The average annual temperature is 5.0 to 6.7 degrees C. The frost-free period is 90 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Budlewis, Eep, Howcree, and Tanner soils. Budlewis and Tanner soils occur on lower terraces and have fine particle-size control sections. Eep soils occur on hillsides and breaks, are very deep and have loamy-skeletal particle-size control sections. Howcree soils have a clayey-skeletal particle-size control section, while occurring on the same terraces as the Ibola soil.

DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderately slow permeability.

USE AND VEGETATION: Ibola soils are used for rangeland. Dominant natural vegetation is Idaho fescue, bluebunch wheatgrass, and mountain big sagebrush.

DISTRIBUTION AND EXTENT: South central Idaho. Ibola soils are of small extent. MLRA 25.

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

SERIES ESTABLISHED: Twin Falls County, Idaho, 1992.

REMARKS: Diagnostic horizons and other features recognized in this pedon:
Mollic epipedon - the zone from the soil surface to 46 cm (A, Bt1 and Bt2 horizons).
Argillic horizon - the zone from 10 to 69 cm (Bt1, Bt2 and Bt3 horizons).
Duripan - the zone from 69 to 71 cm (Bqm horizon).
Paralithic contact - The boundary at 71 cm (Crk horizon).

Particle-size control section - the zone from 4 to 24 inches (Bt1, Bt2 and part of the Bt3 horizon)

The superactive cation exchange activity class was added in 03/2003 to the taxonomic classification by the National Soil Survey Center on request of the Reno MLRA office, without review of the soil series property data. The remainder of this document has not been updated.

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National Cooperative Soil Survey
U.S.A.