LOCATION HUMBOLDT                NV+CA

Established Series
Rev. ELS-RAF-RLB-JBF
05/2016

HUMBOLDT SERIES

The Humboldt series consists of very deep, poorly drained soils that formed in alluvium derived from mixed rocks with a component of volcanic ash. Humboldt soils are on flood plains. Slopes are 0 to 2 percent. The mean annual precipitation is about 180 mm and the mean annual temperature is about 10 degrees C.

TAXONOMIC CLASS: Fine, smectitic, calcareous, mesic Fluvaquentic Vertic Endoaquolls

TYPICAL PEDON: Humboldt silty clay - rangeland. (Colors are for dry soil unless otherwise noted.)

Ap--0 to 20 cm; gray (10YR 5/1) silty clay, black (10YR 2/1) moist; weak medium subangular blocky structure; hard, firm, very sticky and very plastic; many very fine, fine and medium roots; many very fine interstitial and few fine tubular pores; numerous worm casts; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (5 to 30 cm thick)

A--20 to 36 cm; gray (10YR 5/1) silty clay, black (10YR 2/1) moist; moderate fine subangular blocky structure; hard, firm, very sticky and very plastic; many very fine, fine and medium roots; many very fine interstitial and common fine tubular pores; common worm casts; strongly effervescent; moderately alkaline (pH 8.4); clear irregular boundary. (5 to 30 cm thick)

Bk1--36 to 46 cm; light gray (2.5Y 7/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; common fine distinct dark brown (7.5YR 3/4) masses of iron accumulation; strong, medium and fine blocky structure; very hard, firm, very sticky and very plastic; common fine roots; common fine tubular pores; few fine firm lime concretions; few fine and medium distinct white (10YR 8/1) silty lime masses on peds; strongly effervescent; moderately alkaline (pH 8.4); clear wavy boundary. (5 to 20 cm thick)

Bk2--46 to 61 cm; gray (10YR 6/1) silty clay, very dark gray (10YR 3/1) moist; strong fine angular and subangular blocky structure; very hard, firm, very sticky and very plastic; common fine and medium roots; many very fine and few fine tubular pores; few fine, firm lime concretions; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (13 to 30 cm thick)

Bg--61 to 84 cm; greenish gray (5GY 6/1) clay, dark greenish gray (5GY 4/1) moist; common fine distinct dark brown (10YR 3/3) masses of iron accumulation on peds; weak medium and coarse subangular blocky structure; hard, friable, sticky and very plastic; common fine and few medium roots; few fine tubular pores; strongly effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (0 to 30 cm thick)

C1--84 to 97 cm; light gray (10YR 7/2) silty clay loam, gray (10YR 5/1) moist; few fine faint very dark grayish brown (10YR 3/2) masses of iron accumulation on peds; moderate fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common fine roots; common very fine and fine tubular pores; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (10 to 43 cm thick)

C2--97 to 117 cm; light gray (2.5Y 7/2) silt loam, grayish brown (2.5Y 5/2) moist; few distinct coarse very dark gray (10YR 3/1) organic streaks and masses of iron depletion; weak medium and coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common fine roots; common very fine and fine tubular pores; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (13 to 50 cm thick)

C3--117 to 130 cm; light gray (2.5Y 7/2) silt loam, grayish brown (2.5Y 5/2) moist; weak coarse and medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common fine roots; common very fine and fine tubular pores; strongly effervescent; strongly alkaline (pH 8.6); clear smooth boundary. (0 to 23 cm thick)

C4--130 to 152 cm; pale yellow (2.5Y 8/2) silt loam, light brownish gray (2.5Y 6/2) moist; weak coarse and medium and fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common fine roots; many very fine and fine tubular pores; strongly effervescent; moderately alkaline (pH 8.4).

TYPE LOCATION: Pershing County, Nevada; at the south boundary of the town of Lovelock; 300 feet east and 180 feet south of the northwest corner of section 35, T. 27 S., R. 31 E.; USGS Lovelock, NV 7.5 minute topographic quadrangle; latitude 40 degrees 10 minutes 20 seconds N and longitude 118 degrees 28 minutes 32 seconds W; WGS84 Decimal Degrees 40.1722222 latitude, -118.475556 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually saturated for one month or more during most years unless drained.
Mean annual soil temperature: 10 to 12 degrees C.
Mollic epipedon thickness: 25 to 60 cm.
Linear extensibility: 6 to 9 cm.
Reaction: Slightly alkaline to very strongly alkaline, the higher values being only in sodium affected areas.
Carbonates: Slightly effervescent to strongly effervescent throughout; some strata below 50 cm in some pedons are noneffervescent. The calcium carbonate equivalent is less than 15 percent.
Redoximorphic features: Distinct or prominent iron accumulations are in the lower part of the mollic epipedon or immediately below; or if no ironaccumulations, reduced matrix chroma is 1 or less.
Other features: Some pedons have stratified very fine sandy loam to fine sand below 76 cm. Buried A horizons common.

Particle-size control section - Clay content: Averages 35 to 50 percent.

A horizon
Hue: 10YR or 2.5Y or N.
Value: 4 or 5 dry, 6 on surface of some pedons due to deposition, 2 or 3 moist.
Chroma: 0 through 2.
Organic matter content: 2 to 4 percent organic matter.
Salinity (EC): 0 to 32 dS/m.

B and C horizons
Hue: 10YR to 5GY or N.
Value: 6 or 7 dry, 3 through 5 moist. Volcanic ash layers are 8 dry, 6 moist.
Chroma: 0 through 3.
Structure: Moderate or strong prismatic or blocky in the upper part; weak medium and coarse subangular blocky structure in the lower part, or it is massive.
Texture: Stratified silty clay loam to clay with minor substrata of silt loam in some pedons.
Salinity (EC): 0 to 16 dS/m.
Carbonates: Few to many very fine to medium lime concretions or soft segregations in some subhorizons.

COMPETING SERIES: This is the Big Meadow series.

Big Meadow soils have more than 60 percent clay in some part of the textural control section.

GEOGRAPHIC SETTING: Humboldt soils are on flood plains. These soils formed in alluvium derived from mixed rock sources with a component of volcanic ash. Slopes are 0 to 2 percent. Elevations are 1,190 to 1,965 meters. The climate is cool, semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 125 to 200 mm, mean annual temperature is 9 to 11 degrees C, and the frost-free season is 100 to 130 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lovelock, Ocala, Placeritos, Rose Creek, Ryepatch and Sonoma soils. Lovelock soils have mixed mineralogy with diatomaceous earth and volcanic ash in the clay fraction. Ocala, Placeritos, and Sonoma soils are fine-silty and lack a mollic epipedon. Rose Creek soils are coarse-loamy. Ryepatch soils are very-fine and have cracks extending to a depth of more than 50 cm.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Poorly drained. Drained areas are a result of entrenchment of stream channels, impoundment of normal stream flow in reservoirs or diversion of water for irrigation. Wet phases are recognized for pot hole areas that are inundated during flooding periods. Drained phases are also recognized as a result of artificial drainage. Water tables commonly range from 15 to 60 cm below the surface, but are deeper for drained phases. The soils are usually subject to flooding one year out of two if unprotected. Very slow runoff; moderately low saturated hydraulic conductivity.

USE AND VEGETATION: Cropland, rangeland and wildlife habitat. Large areas are leveled and cultivated. Alfalfa, small grains, row crops and grass pastures are grown. Native areas subject to periodic flooding produce native meadows consisting of creeping wildrye, basin wildrye, sedges and saltgrass. These are either grazed or cut for meadow hay. Greasewood, saltgrass, and alkali sacaton grow on the more salt and sodium affected areas.

DISTRIBUTION AND EXTENT: Northern Nevada. These soils are extensive. MLRA 24, 25, 27 28B.

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

SERIES ESTABLISHED: The Humboldt series was first described by Dr. Marbut, and recognized in the Atlas of American Agriculture, Part III, Soils of the United States, 1935. It was redefined in the Lovelock Soil Survey in Pershing County, Nevada, 1957.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 25 cm (Ap and A horizons).
Seasonal water table - Within a depth of 15 to 60 cm.
Endosaturation - The zone from 36 to 117 cm (Bk1, Bk2, Bq, C1 and C2 horizons).Vertic feature - Linear extensibility: 6 to 9 cm.
Particle-size control section - The zone from 25 to 100 cm (Bk1, Bk2, Bg, C1 and parts of the A and C2 horizons).

ADDITIONAL DATA: SSIR No. 23.

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National Cooperative Soil Survey
U.S.A.