LOCATION SWOPE                   NV

Established Series
Rev. WED/ELS/JVC
05/2016

SWOPE SERIES

The Swope series consists of very deep, somewhat poorly drained soils that formed in alluvium derived from mixed igneous rocks. Swope soils are on flood plains. Slopes are 0 to 1 percent. The mean annual precipitation is about 127 mm and the mean annual temperature is about 12 degrees C.

TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive, calcareous, mesic Fluvaquentic Endoaquolls

TYPICAL PEDON: Swope clay loam--irrigated cropland. (Colors are for dry soil unless otherwise noted.)

Ap--0 to 18 cm; gray (10YR 5/1) clay loam, very dark gray (10YR 3/1) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; many fine and very fine, common medium and coarse roots; common fine tubular and common very fine interstitial pores; moderately alkaline (pH 8.2); clear smooth boundary. (13 to 20 cm thick)

A1--18 to 38 cm; gray (10YR 5/1) silty clay loam, very dark gray (10YR 3/1) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; many fine and very fine, common medium and coarse roots; common fine and very fine tubular and interstitial pores; slightly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (15 to 23 cm thick)

A2--38 to 51 cm; gray (10YR 5/1) silty clay loam, very dark gray (10YR 3/1) moist; weak medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common fine and very fine roots; common fine and very fine tubular and interstitial pores; slightly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (13 to 18 cm thick)

C1--51 to 69 cm; light brownish gray (2.5Y 6/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; massive; hard, firm, moderately sticky and moderately plastic; few very fine roots; few very fine tubular pores; common medium prominent brown (7.5YR 4/4) moist masses of iron accumulation; slightly effervescent; moderately alkaline (pH 8.4); abrupt smooth boundary. (10 to 41 cm thick)

2C2--69 to 152 cm; light brownish gray (10YR 6/2) stratified sand and coarse sand, dark grayish brown (10YR 4/2) moist; single grain; loose, nonsticky and nonplastic; few very fine roots; many fine interstitial pores; common medium prominent brown (7.5YR 4/4) moist masses of iron accumulation; slightly alkaline (pH 7.8).

TYPE LOCATION: Churchill County, Nevada; in the Lahontan Valley about 8.5 miles south of Fallon on the Section Ranch; in the approximate center of section 7, T. 17 N., R. 29 E.; USGS South of Fallon 7.5 minute topographic quadrangle; latitude 39 degrees 21 minutes 5.71 seconds N. and longitude 118 degrees 46 minutes 20.54 seconds W.; WGS84 Decimal Degrees 39.3517778 latitude, -118.7725000 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: These soils are normally saturated in the moisture control section for at least one month during the Spring except where artificially drained; Short seasonal periods of aquic moisture regime under natural conditions.
Mean annual soil temperature: 12 to 14 degrees C.
Mollic epipedon thickness: 41 to 61 cm.
Depth to strongly contrasting sandy material: 51 to 97 cm, but is dominantly between 61 to 79 cm.
Salinity (EC): 0 to 32 mmhos/cm.
Sodicity (SAR): 0 to 30.

Particle-size control section - Clay content: 27 to 35 percent in the upper part and 0 to 5 percent in the strongly contrasting lower part.

A horizons
Hue: 10YR or 2.5Y.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 1 or 2, dry or moist. Chroma of 2 is accompanied by distinct or prominent redox concentration in the lower A horizon.
Organic matter content: 1 to 3 percent.

C1 horizon
Hue 10YR or 2.5Y.
Value 3 or 4 moist.
Chroma: 1 or 2, dry or moist.
Texture: Silty clay loam or clay loam; may include thin strata of finer or coarser textured materials.
Effervescence: Slightly effervescent or strongly effervescent.

2C2 horizon
Hue: 10YR through 5Y.
Value: 6 through 8 dry, 4 or 5 moist.
Chroma: 1 or 2, dry or moist.
Texture: Dominantly sand or coarse sand but has strata of very coarse sand, or fine gravel in some pedons. Any of these textures may be modified by up to 25 percent 5 mm gravel.
Redoximorphic features: Common or many, fine to very coarse, distinct to prominent redox concentrations of iron.

COMPETING SERIES: These are the Lex, Loveland, and Woofus series.

Lex and Loveland soils have a more persistent aquic moisture regime and are not as dry during summer months. Woofus soils have mean annual soil temperature of 8 to 10 degrees C and have surficial deposits of loess and volcanic ash.

GEOGRAPHIC SETTING: Swope soils are on flood plains. These soils formed in alluvium derived from mixed igneous rocks including granite, basalt and andesite. Slopes are 0 to 1 percent. Elevations range from 1,158 to 1,219 meters. The climate is arid with cool, moist winters and hot, dry summers. The mean annual precipitation is 100 to 150 mm and the mean annual temperature is 11 to 13 degrees C. The mean January temperature is -1 to 0 degrees C and the mean July temperature is 21 to 22 degrees C. The frost-free period is 120 to 140 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bunejug, Carson, Erber, and Stillwater soils. Bunejug soils are highly stratified and coarse-loamy. Carson soils are very-fine. Erber soils are sandy. Stillwater soils are fine.

DRAINAGE AND PERMEABILITY: Somewhat poorly drained; moderately slow permeability (moderately high saturated hydraulic conductivity) in the upper part and very rapid (very high saturated hydraulic conductivity) in the strongly contrasting lower part. Endosaturation is present with an apparent seasonal high water table between 3 and 5 feet (moderately deep and deep free water occurrence classes) between April and July. Cumulative annual duration class is Common. Originally these soils were formed under more poorly drained conditions than are present today. Damming of the Carson River, diversion of river water for irrigation, and local drainage improvements have lowered the water table.

USE AND VEGETATION: Most areas of Swope soils are cultivated. Alfalfa, small grains, sugar beets, and legume-grass pastures are the principal crops. The dominant native vegetation is black greasewood and inland saltgrass. Prior to the damming of the Carson River and diverting water for irrigation purposes the dominant vegetation probably consisted of meadow grasses.

DISTRIBUTION AND EXTENT: Western Nevada. These soils are not extensive with about 1,900 acres of the series mapped to date. MLRA 27.

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

SERIES ESTABLISHED: Churchill County (Fallon-Fernley Area), Nevada, 1971.

REMARKS: Diagnostic horizon and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 51 cm (Ap, A1, and A2 horizons).
Endosaturation feature - The condition of ground water with an upper boundary between 91 and 152 cm at certain times during normal years (part of the 2C2 horizon).
Strongly contrasting feature - The boundary at 69 cm.
Particle-size control section - The zone from 25 to 100 cm (A2 and C1 horizons and parts of the A1 and 2C2 horizons).

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National Cooperative Soil Survey
U.S.A.