LOCATION HAMTAH                  NV+UT

Established Series
Rev. CWL-JVC-TM-JBF
02/2012

HAMTAH SERIES

The Hamtah series consists of very deep, well drained soils that formed in colluvium and residuum derived from welded tuff and other volcanic rocks. Hamtah soils are on hills and mountains. Slopes are 4 to 50 percent. The mean annual precipitation is 450 mm and the mean annual temperature is 5 degrees C.

TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Vitrandic Argixerolls

TYPICAL PEDON: Hamtah very stony ashy sandy clay loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered by approximately 20 percent gravel, 10 percent cobbles, and 10 percent stones.

A1--0 to 25 cm; dark grayish brown (10YR 4/2) very stony ashy sandy clay loam, very dark brown (10YR 2/2) moist; moderate fine and medium granular structure; soft, very friable, moderately sticky and moderately plastic; many very fine, and few fine, medium, and coarse roots; many very fine interstitial pores; 20 percent gravel, 10 percent cobbles, and 10 percent stones; slightly acid (pH 6.5); gradual smooth boundary. (15 to 30 cm thick)

A2--25 to 53 cm; dark grayish brown (10YR 4/2) gravelly ashy sandy clay loam, very dark brown (10YR 2/2) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; many very fine, and few fine, medium, and coarse roots; many very fine interstitial, and many very fine, and few fine tubular pores; 25 percent gravel and 5 percent cobbles; neutral (pH 6.6); gradual smooth boundary. (15 to 36 cm thick)

Bt1--53 to 84 cm; brown (7.5YR 5/2) gravelly ashy clay loam, brown (7.5YR 4/2) moist; moderate medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many very fine, and few fine and medium roots; many very fine interstitial and tubular pores; many distinct clay films lining pores, on faces of peds and as bridges between sand grains; 30 percent gravel; neutral (pH 6.8); gradual smooth boundary. (23 to 38 cm thick)

Bt2--84 to 104 cm; pinkish gray (7.5YR 6/2) very gravelly ashy clay loam, brown (7.5YR 4/2) moist; strong coarse subangular blocky structure parting to moderate medium subangular blocky; hard, friable, very sticky and very plastic; common very fine roots; many very fine interstitial and tubular pores; many distinct clay films lining pores, on faces of peds and as bridges between sand grains; 50 percent gravel and 5 percent cobbles; neutral (pH 6.6); clear smooth boundary. (20 to 38 cm thick)

Bt3--104 to 152 cm; variegated brown (7.5YR 5/4), strong brown (7.5YR 5/6), and white (10YR 8/1) gravelly ashy clay loam, dark brown (7.5YR 3/3), brown (7.5YR 5/2), and white (10YR 8/1) moist; strong coarse subangular blocky structure parting to moderate fine and very fine angular blocky; hard, firm, moderately sticky and moderately plastic; few very fine and fine roots; few very fine tubular pores; many distinct clay films along fracture planes of pararock fragments; 30 percent gravel; 20 percent paragravel and 5 percent paracobbles; neutral (pH 7.0).

TYPE LOCATION: Lincoln County, Nevada; about 25 miles northeast of Pioche and 7 miles west of Meadow Valley Wash at the Confidence Mine; approximately 900 feet west and 1,300 feet north of the southeast corner of section 17, T. 3 N., R. 71 E.; USGS Rice Mountain 7.5 minute topographic quadrangle; latitude 38 degrees 6 minutes 53.9 seconds N and longitude 114 degrees 3 minutes 11.7 seconds W; UTM zone 11, 758341e, 4222675n; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in the moisture control section during winter and spring, dry during summer and fall and dry in all parts for 45 consecutive days following the summer solstice; intermittently moist in some part of the moisture control section for 10 to 20 days cumulative between July and September following summer convection storms. Typic xeric soil moisture regime.
Mean annual soil temperature: 6 to 7 degrees C.
Mean summer soil temperature: 16 to 17 degrees C.
Mollic epipedon thickness: 50 to 66 cm.
Depth to base of argillic horizon; Greater than 152 cm.

Particle-size control section - Clay content: 35 to 50 percent.
Rock fragments: 35 to 50 percent mainly gravel and cobbles. Lithology of fragments is welded tuff and other volcanic rocks.

A horizons
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 1 or 2, dry or moist.
Organic matter content: 2 to 6 percent.
Reaction: Slightly acid to neutral.
Mineralogy: 20 to 30 percent volcanic glass in the 0.2 to 2 mm fraction and averages 0.1 to 0.2 percent Al plus 1/2Fe, extracted by ammonium oxalate.

Bt1 and Bt2 horizons
Hue: 7.5YR or 10YR.
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2 through 4, dry or moist.
Texture: Ashy clay loam or clay.
Clay content: 35 to 50 percent.
Structure: Subangular blocky or prismatic.
Mineralogy: 15 to 30 percent volcanic glass in the 0.2 to 2 mm fraction and averages 0.1 to 0.25 percent Al plus 1/2Fe, extracted by ammonium oxalate.

Bt3 horizon
Hue: 5YR through 10YR.
Value: 5 through 8 dry, and 3 through 8 moist.
Chroma: 1 through 6, dry or moist.
Clay content: 27 to 35 percent.
Rock fragments: 15 to 35 percent, mainly gravel. 10 to 40 percent paragravel and paracobbles are present in most pedons.
Mineralogy: 20 to 30 percent volcanic glass in the 0.2 to 2 mm fraction and averages 0.05 to 0.2 percent Al plus 1/2Fe, extracted by ammonium oxalate.
Other features: Up to 50 percent discontinuous areas of the original rock structure are visible as pararock fragments that part to weak or moderate fine and medium angular or subangular blocky structure. Its lower boundary is diffuse and grades gradually to hard bedrock.

COMPETING SERIES: These are the Breeseranch, Dupratt, Erakatak, Finsel, Home Camp, Humarel, Maule, Menbo, Potlid, Shotsprings, Squatterflat and Wiltop. series.

Breeseranch soils are 100 to 150 cm to a lithic contact and have an O horizon. Dupratt, Finsel, Humarel, Menbo, Potlid, and Shotsprings soils are 50 to 100 cm to a lithic contact. Home Camp soils are 50 to 100 cm to a paralithic contact. Maule soils are 58 to 89 cm to a paralithic contact. Squatterflat soils are not intermittently moist in some part of the moisture control section for 10 to 20 days cumulative between July and September following summer convection storms. Wiltop soils are100 to 150 cm to a lithic contact.

GEOGRAPHIC SETTING: Hamtah soils are on hills and mountains. These soils formed in colluvium and residuum derived from welded tuff and other volcanic rocks. Slopes are 4 to 50 percent. Elevations range from 1,900 to 2,600 meters. The climate is semiarid with cold, moist winters and cool, dry summers. The mean annual precipitation is 400 to 500 mm, most of which comes as snow. The mean annual temperature is 4 to 6 degrees C and the frost-free period is 40 to 70 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Nevtah, Udel, Wilpar, Winu, and Winz soils. Nevtah soils are loamy-skeletal, moderately deep to lithic contacts, have thick mollic epipedons, and do not have argillic horizons. Udel soils are loamy-skeletal, very shallow to lithic contacts, and do not have argillic horizons. Wilpar soils are deep to paralithic contacts and have a frigid temperature regime. Winu soils are fine-loamy, moderately deep to lithic contacts,. Winz soils have ochric epipedons and albic horizons.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; moderately low saturated hydraulic conductivity.

USE AND VEGETATION: Hamtah soils are used for wildlife habitat and livestock grazing. The potential native vegetation is mainly mountain big sagebrush, Utah serviceberry, antelope bitterbrush, and snowberry with scattered singleleaf pinyon and curlleaf mountainmahogany. Grasses present are bluebunch wheatgrass, basin wildrye, bottlebrush squirreltail, and Thurber's needlegrass. This pedon is correlated to Ecological Site R028AY066NV, Gravelly Loam 12-14 P.Z.

DISTRIBUTION AND EXTENT: East-central Nevada and west-central Utah. These soils are moderately extensive. The series concept and main acreage is in MLRA 28A, while other acreage occurs in MLRA 47 in Utah.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona.

SERIES ESTABLISHED: Lincoln County (Meadow Valley Area), Nevada, 1971.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon- The zone from the soil surface to 53 cm (A1 and A2 horizons).
Argillic horizon - The zone from 53 to 152 cm (Bt1, Bt2, and Bt3 horizons).
Vitrandic feature - The zone from the soil surface to 75 cm (A1 and A2 horizons and part of the Bt1 horizon).
Particle-size control section - The zone from 53 to 103 cm (Bt1 horizon and part of the Bt2 horizon).

ADDITIONAL DATA:
Author and reviewer initials were shortened to the most recent in 2007. Other reviewer initials are: LNL-LR-ELS.

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National Cooperative Soil Survey
U.S.A.