LOCATION ZAPA                    NV

Established Series
Rev. ARW-DWW-JVC-JBF
12/2019

ZAPA SERIES

The Zapa series consists of moderately deep to a duripan, well drained soils that formed in alluvium derived from mixed rocks, loess, and volcanic ash. Zapa soils are on fan remnants. Slopes are 2 to 50 percent. The mean annual precipitation is about 230 mm and the mean annual temperature is about 8 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Xereptic Haplodurids

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

A1--0 to 5 cm; light brownish gray (10YR 6/2) very gravelly silt loam, very dark grayish brown (10YR 3/2) moist; moderate very thin and thin platy structure; soft, very friable, slightly sticky and slightly plastic; common very fine, few fine and medium roots; many very fine vesicular pores; 55 percent gravel; slightly alkaline (pH 7.6); clear smooth boundary. (3 to 10 cm thick)

A2--5 to 13 cm; brown (10YR 5/3) very gravelly silt loam, dark brown (10YR 3/3) moist; moderate very thin and thin platy structure; soft, very friable, slightly sticky and slightly plastic; common very fine, few fine and medium roots; common very fine tubular pores; 40 percent gravel; slightly alkaline (pH 7.8); clear smooth boundary. (5 to 18 cm thick)

Bw--13 to 18 cm; brown (10YR 5/3) very gravelly silt loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, few fine and medium roots; common very fine tubular pores; common very thin silica and silt coats lining pores; 40 percent gravel; slightly alkaline (pH 7.8); clear wavy boundary. (0 to 10 cm thick)

Bkq1--18 to 30 cm; pale brown (10YR 6/3) very gravelly silt loam, yellowish brown (10YR 5/4) moist; massive; soft, very friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine interstitial pores; 25 percent weak discontinuous silica cementation; many very fine to very coarse silica chips; 45 percent gravel; many silica and carbonate pendants on bottoms of rock fragments; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (8 to 18 cm thick)

2Bkq2--30 to 64 cm; very pale brown (10YR 8/3) very gravelly coarse sandy loam, pale brown (10YR 6/3) moist; massive; hard, firm and brittle, nonsticky and nonplastic; common very fine and fine roots; common very fine interstitial pores; 10 percent discontinuous strong silica cementation; many very fine to very coarse silica chips; common very thin silica and silt coats lining pores; 55 percent gravel; many silica and carbonate pendants on bottoms of rock fragments; violently effervescent; moderately alkaline (pH 8.4); abrupt wavy boundary. (30 to 40 cm thick)

2Bkqm--64 to 107 cm; duripan; strong medium and thick platy structure; very hard and very firm; strongly cemented by secondary silica; common very fine and fine roots in fractures between plates; thin, discontinuous silica and carbonate lamina throughout various parts of horizon; 20 percent of horizon is violently effervescent in a noneffervescent matrix; clear wavy boundary. (13 to 46 cm thick)

3Bqk--107 to 152 cm; very pale brown (10YR 8/3) extremely gravelly coarse sandy loam, pale brown (10YR 6/3) moist; massive; very hard, very firm and brittle, nonsticky and nonplastic; many silica and carbonate pendants on bottoms of rock fragments; 25 percent of horizon is discontinuously, strongly silica-cemented; 75 percent gravel; violently effervescent on carbonate pendants, noneffervescent matrix; strongly alkaline (pH 8.6)

TYPE LOCATION: Elko County, Nevada; approximately 12 miles southwest of Jackpot; about 2,640 feet south and 10 feet west of the northeast corner of section 1, T. 45 N., R. 63 E.; USGS Contact 7.5 minute topographic quadrangle; latitude 41 degrees 48 minutes 58 seconds N and longitude 114 degrees 46 minutes 51 seconds W; WGS84 Decimal Degrees 41.8160889 latitude, -114.7808333 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry, moist in the winter and spring, dry June through early November; aridic soil moisture regime that borders on xeric.
Mean annual soil temperature: 8 to 11 degrees C.
Depth to horizons with firm, brittle matrix: 13 to 36 cm.
Depth to duripan: 50 to 76 cm.

Particle-size control section - Clay content: 10 to 20 percent.
Rock fragments: 35 to 60 percent, mainly gravel. Lithology of fragments is mixed rocks.

A horizons
Value: 5 or 6 dry, 3 or 4 moist; the upper 18 cm of the soil when mixed has a dry value of 6 and moist value of 4.
Chroma: 2 or 3, dry or moist.
Reaction: Slightly alkaline or moderately alkaline.

Bkq1 horizon
Value: 6 through 8 dry, 4 through 6 moist.
Chroma: 3 or 4, dry or moist.
Structure: Weak coarse subangular blocky or it is massive.
Reaction: Moderately alkaline or strongly alkaline.
Calcium carbonate equivalent: 0 to 3 percent.
Other features: 10 to 50 percent discontinuous weak silica and carbonate cementation.

2Bkq2 horizon
Value: 6 through 8 dry, 4 through 6 moist.
Chroma: 3 or 4, dry or moist.
Texture: Very gravelly coarse sandy loam, very gravelly sandy loam, or very gravelly silt loam.
Rock fragments: 35 to 60 percent total with 35 to 55 percent gravel and 0 to 10 percent cobbles.
Structure: Weak coarse subangular blocky or it is massive.
Consistence: Hard when dry, firm and brittle when moist.
Reaction: Moderately alkaline or strongly alkaline.
Salinity (EC): 0 to 4 mmhos/cm.
Sodicity (SAR): 0 to 12.
Calcium carbonate equivalent: 5 to 10 percent.
Other features: 10 to 50 percent discontinuous weak silica and carbonate cementation.

2Bkqm horizon
Value: 7 or 8 dry, 5 through 7 moist.
Chroma: 3 or 4 moist, dry or moist.
Structure: Strong medium to very thick platy or it is massive.
Cementation: Continuous strong cementation with the average lateral distance between fracture points of more than 10 cm.

3Bqk horizon
Texture: Extremely gravelly coarse sandy loam or extremely gravelly sandy loam.
Rock fragments: 60 to 80 percent, mainly gravel with up to 20 percent cobbles.
Reaction: Moderately alkaline or strongly alkaline.
Salinity (EC): 0 to 4 mmhos/cm.
Sodicity (SAR): 13 to 30.
Calcium carbonate equivalent: 5 to 10 percent.

COMPETING SERIES: This is the Ellum series.

Ellum soils lack subhorizons above the duripan with firm consistence and a brittle manner of failure when moist.

GEOGRAPHIC SETTING: Zapa soils are on fan remnants. These soils formed in alluvium derived from mixed rocks, loess, and volcanic ash. Slopes are 2 to 50 percent. Elevations range from 1,525 to 1,985 meters. The climate is 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 period is 100 to 120 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chuska, Deepeek, and Jackpot soils. Chuska and Deepeek soils have argillic horizons and indurated duripans. Jackpot soils are ashy and shallow to paralithic contacts.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; high surface runoff; moderately high saturated hydraulic conductivity.

USE AND VEGETATION: Zapa soils are used for rangeland and wildlife habitat. The present vegetation is mainly black sagebrush, shadscale, bottlebrush squirreltail, and cheatgrass.

DISTRIBUTION AND EXTENT: Northeastern Nevada. These soils are moderately extensive. MLRA 25.

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

SERIES ESTABLISHED: Elko County (Northeast Part), Nevada, 1986.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 18 cm (A1, A2, and Bw horizons).
Calcic horizon - The zone from 30 to 64 cm (2Bkq2 horizon).
Strongly cemented duripan - The zone from 64 to 107 cm (2Bkqm horizon).
Particle size control section - The zone from 25 to 64 cm (2Bkq2 and part of the Bkq1 horizons).

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National Cooperative Soil Survey
U.S.A.