LOCATION CREDO                   NV

Established Series
Rev. WMA/ELS/JBF
11/2016

CREDO SERIES

The Credo series consists of very deep, well drained soils that formed in lake deposits derived from shale, chert, limestone and dolomite with local loss deposition. Credo soils are on beach terraces. Slopes are 2 to 8 percent. The mean annual precipitation is about 250 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Xeric Haplargids

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

A1--0 to 5 cm; grayish brown (10YR 5/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate medium and fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine roots; many very fine and fine interstitial pores; 20 percent gravel; neutral (pH 6.8); abrupt smooth boundary. (0 to 5 cm thick)

A2--5 to 15 cm; light brownish gray (10YR 6/2) loam, dark grayish brown (10YR 4/2) moist; moderate thin platy structure'; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; many very fine interstitial pores; 10 percent gravel; neutral (pH 7.0); abrupt smooth boundary. (15 to 25 cm thick)

Bt1--15 to 25 cm; pale brown (10YR 6/3) loam, brown (10YR 4/3) moist; weak medium and fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; common very fine tubular pores; few very faint clay films in pores; 10 percent gravel; neutral (pH 7.0); abrupt wavy boundary. (0 to 10 cm thick)

Bt2--25 to 46 cm; pale brown (10YR 6/3) loam, brown (10YR 4/3) moist; weak medium and fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine roots; common very fine pores; few very faint clay films in pores; 10 percent gravel; neutral (pH 7.2); abrupt wavy boundary. (10 to 20 cm thick)

Bt3--46 to 61 cm; pale brown (10YR 6/3) gravelly clay loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many very fine roots; many very fine, and few fine tubular pores; common very faint clay films in pores and on faces of peds; 15 percent gravel; neutral (pH 7.2); clear wavy boundary. (15 to 20 cm thick)

2Btqk--61 to 86 cm; pale brown (10YR 6/3) gravelly sandy clay loam; brown (10YR 4/3) moist; massive; hard, friable, moderately sticky and moderately plastic; few very fine roots; common very fine tubular pores; many faint clay films in pores and bridging mineral grains; 30 percent gravel and cobbles; very thin silica and carbonate coats on underside of gravel; noneffervescent matrix but strongly effervescent under coarse fragments; moderately alkaline (pH 8.2); clear wavy boundary. (20 to 30 cm thick)

2Bqk--86 to 152 cm; pale brown (10YR 6/3) very cobbly coarse sandy loam, brown (10YR 5/3) moist; massive; soft, very friable, slightly sticky and nonplastic; few very fine roots; many very fine interstitial pores; 55 percent cobbles and gravel; thin silica and carbonate coats on underside of coarse fragments; matrix is noneffervescent but slightly effervescent under coarse fragments; strongly alkaline (pH 8.6).

TYPE LOCATION: Eureka County, Nevada; about five miles north of Eureka; about 1,900 feet north and 1,700 feet east of the southwest corner of section 19, T. 20 N., R. 54 E.; USGS Eureka 7.5 minute topographic quadrangle; latitude 39 degrees 34 minutes 58 degrees N and 115 degrees 56 minutes 19 degrees W; WGS84 Decimal Degrees 39.5827778 latitude, -115.9386111 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry; moist in winter and spring; aridic soil moisture regime bordering on xeric.
Mean annual soil temperature: 7 to 8 degrees C.

Particle-size control section - Clay content: Averages 20 to 35 percent.
Rock fragments: 0 to 35 percent.

A horizon
Value: 5 or 6 dry, 3 or 4 moist.
Structure: weak or moderate fine or medium granular or thin to thick platy, or it is massive.

Bt1 and Bt2 horizons
Chroma: 2 or 3,
Structure: weak or moderate fine or medium subangular blocky.
Texture: Loam, silt loam, or clay loam.

Bt3 and Btqk horizons
Chroma: 3 or 4.
Texture: Sandy clay loam, loam or clay loam.
Rock fragments: 10 to 35 percent gravel.
Structure: Weak to strong fine to coarse subangular blocky structure or massive.
Reaction: Neutral through moderately alkaline

2Bqk horizon
Rock fragments: 35 to 60 percent, dominantly gravel and cobbles.
Reaction: Moderately alkaline through very strongly alkaline.
Effervescence: Noneffervescent to slightly effervescent in the matrix.
Other features: Moderately thick silica and carbonate coats and pendants on underside of coarse fragments.

COMPETING SERIES: These are the Favret and Pedoli series.

Favret soils have bedrock at 50 to 100 cm. Pedoli soils are strongly effervescent to violently effervescent in the matrix of the Bqk horizon.

GEOGRAPHIC SETTING: Credo soils are on beach terraces. These soils formed in alluvium derived from shale, chert, limestone and dolomite that has been worked by wave action, with some local loess deposition. Slopes are 2 to 8 percent. Elevations are 1,770 to 1,925 meters. The climate is cool, semiarid continental. The mean annual precipitation is 200 to 300 mm, most of which falls as snow; mean annual temperature is 6 to 7 degrees C., and the mean summer temperature is 15 to 17 degrees C. The frost free season is 70 to 110 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Holtle, Kobeh and Rito soils. Holtle soils have mollic epipedons. Kobeh soils have cambic horizons and loamy- skeletal particle-size control sections. Rito soils have mollic epipedons and calcic horizons.

DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderately slow permeability; moderately high saturated hydraulic conductivity.

USE AND VEGETATION: Rangeland and wildlife habitat. Vegetation is big sagebrush, bluegrass, rabbitbrush, cheatgrass, Great Basin wildrye and squirreltail.

DISTRIBUTION AND EXTENT: Northeastern Nevada. MLRA 28B. The series is inextensive with about 3,800 acres.

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

SERIES ESTABLISHED: Eureka County (Diamond Valley Area), Nevada, 1971.

REMARKS: Credo soils were formerly classified as Sierozems.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 15 cm (A1 and A2 horizons).
Argillic horizon - The zone from 15 to 86 cm (Bt1, Bt2, Bt3 and 2Btqk horizons).
Particle-size control section - The zone from 15 to 65 cm (Bt1, Bt2, Bt3 and part of the 2Btqk horizons).

ADDITIONAL DATA: During MLRA updates other series differences or possible correlation with Pedoli series should be checked and verified.

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National Cooperative Soil Survey
U.S.A.