LOCATION TOBA                    NV

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

TOBA SERIES

The Toba series consists of very deep, poorly drained soils that formed in alluvium derived from mixed rocks over lacustrine sands. Toba soils are on axial stream floodplains. Slopes are 0 to 2 percent. The mean annual precipitation is about 250 mm and the mean annual air temperature is about 9 degrees C.

TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive, mesic Aquic Haplocalcids

TYPICAL PEDON: Toba loam--rangeland. (Colors are for dry soil unless otherwise noted.)

A--0 to 10 cm; very dark gray (10YR 3/1) loam, black (10YR 2/1) moist; moderate medium and thick platy structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine, fine, and medium roots; common fine tubular pores; strongly effervescent; strongly alkaline (pH 8.5); abrupt wavy boundary. (5 to 13 cm thick)

Bk--10 to 36 cm; white (5Y 8/1) clay loam, light gray (5Y 7/2) moist; few to common dark gray (10YR 4/1) fine and medium organic stains in root channels and faces of peds tonging from above; moderate fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common fine and medium roots; common fine tubular and interstitial pores; violently effervescent; 5 percent fine and medium slightly hard carbonate and silica nodules; violently effervescent; strongly alkaline (pH 8.8); clear smooth boundary. (15 to 36 cm thick)

2Bk1--36 to 58 cm; light gray (5Y 7/2) loamy fine sand, light olive gray (5Y 6/2) moist; few to common dark olive gray (5Y 3/2) organic stains; tonguing from above few fine distinct olive yellow (2.5Y 6/6) iron redox concentrations; massive; slightly hard, friable, nonsticky and nonplastic; common fine and medium roots; common fine interstitial pores; strongly effervescent; common fine and medium pale yellow (5Y 8/2) carbonate filaments and threads with few fine soft carbonate masses; strongly effervescent; strongly alkaline (pH 8.7); clear wavy boundary. (18 to 30 cm thick)

2Bk2--58 to 86 cm; light gray (5Y 7/2) fine sand, olive gray (5Y 5/2) moist; few fine distinct olive yellow (2.5Y 6/6) redox concentrations and manganese stains massive; soft; very friable, nonsticky and nonplastic; common fine and medium interstitial pores; slightly effervescent; 15 percent fine and medium carbonate and silica nodules; moderately alkaline (pH 8.0); abrupt smooth boundary. (20 to 30 cm thick)

2Bk3--86 to 152 cm; light gray (5Y 7/2) sand, olive (5Y 5/3) moist; few fine redox concentrations, dark gray (5Y 4/1) single grain; loose, nonsticky and nonplastic; common fine and medium interstitial pores; slightly effervescent; few fine and medium carbonate and silica nodules; slightly effervescent; moderately alkaline (pH 8.0).

TYPE LOCATION: Elko County, Nevada; about 18 miles south of Wells in Clover Valley; in an unsectionalized area; approximately 2400 feet north of Bapt Reservoir; about 1900 feet north and 200 feet west of the projected southeast corner of section 21, T. 34 N., R. 63 E.; USGS Ventosa 7.5 minute topographic quadrangle; latitude 40 degrees 48 minutes 49 seconds N and longitude 114 degrees 51 minutes 10 seconds W; WGS84 Decimal Degrees 40.8136111 latitude, -114.8527778 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Saturated below depths of 46 to 61 cm for one month during most years mainly during late winter and early spring. The moisture control section is dry from late May through October in most years. Drained phases are recognized.
Soil temperature: 8 to 11 degrees C.
Depth to contrasting horizon: 30 to 64 cm.

Particle-size control section - Percent clay: 20 to 40 percent in the upper part and less than 5 percent in the lower part.

A horizon
Hue: 10YR, 2.5Y or 5Y.
Value: 2 through 4 dry.
Chroma: 1 or 2.

Bk horizon
Hue: 5Y or 10YR.
Value: 7 or 8 dry, 5 through 7 moist.
Chroma: 1 through 3.
Sodium absorption ratio (SAR): 15 to 35.
Other Features: Few to common organic stains along root channels tonguing from A horizon.

2Bk1, 2Bk2 and 2Bk3 horizons
Value: 6 or 7 dry, 4 through 7 moist.
Structure: Massive or single grained.
Consistence: Loose to slightly hard dry, loose to friable moist.
Chroma: 2 through 4.
Mottles: Few fine distinct redoximorphic concentrations from 36 to 150 cm.
Effervescence: Noneffervescent through strongly effervescent.
Other features: Lacustrine silts and clays may occur in some thin strata below 100 cm in some pedons. A few strata may have up to 30 percent gravel in some pedons. Few to common carbonate and silica nodules are common. Few to common organic stains in upper subhorizons tonguing from the A horizon.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Toba soils are on axial stream flood plains. These soils formed in alluvium derived from mixed rocks over lacustrine sands. Slopes are 0 to 4 percent. Elevations are 1,710 to 1,740 meters. The climate is cool, semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 200 to 250 mm, mean annual temperature is 7 to 10 degrees C, and the frost-free season is 100 to 120 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Appian, Hulderman and Mysol series. Appian soils have a natric horizon. Hulderman soils have a mollic epipedon and Mysol soils lack a calcic horizon.

DRAINAGE AND PERMEABILITY: Poorly drained; slow to medium runoff; moderately slow over very rapid permeability.

USE AND VEGETATION: Rangeland and wildlife habitat. The present vegetation is mainly mat muhly.

DISTRIBUTION AND EXTENT: Valleys of northeastern Nevada. These soils are not extensive. MLRA 28B.

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

SERIES ESTABLISHED: Elko County, Nevada, Southeast Part 1991.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to about 18 cm (A and part of Bk1 horizons).
Calcic horizon - The zone from 10 to 58 cm (Bk1 and 2Bk2) horizon).
Contrasting particle-size class - The boundary at about 36 cm.
Redox concentrations - The zone from 36 to 152 cm (2Bk1, 2Bk2 and 2Bk3 horizons).
Particle-size control section - The zone from 25 to 100 cm (Bk1, 2Bk2, 2Bk3 and part of the 2Bk3 horizons).

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National Cooperative Soil Survey
U.S.A.