LOCATION ACTI                    NV

Established Series
Rev. BKP/JBF
05/2016

ACTI SERIES

The Acti series consists of shallow, well drained soils that formed in residuum and colluvium derived from welded tuff. Acti soils are on mountains. Slopes are 15 to 50 percent. The mean annual precipitation is about 350 mm and the mean annual temperature is about 10 degrees C.

TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Aridic Lithic Argiustolls

TYPICAL PEDON: Acti very gravelly loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is partially covered with 15 percent cobbles and 40 percent gravel.

Oi--0 to 2 cm; slightly decomposed plant material composed of pinyon needles and oak leafs.

A--2 to 5 cm; dark reddish brown (5YR 3/2) very gravelly loam, dark reddish brown (5YR 2.5/2) moist; moderate fine granular structure; soft, very friable, slightly sticky and nonplastic; many very fine and fine roots; many very fine and fine interstitial pores; 45 percent gravel and 10 percent cobbles; slightly alkaline (pH 7.4); clear smooth boundary. (5 to 8 cm thick)

Bt1--5 to 10 cm; dark reddish brown (5YR 3/2) very gravelly clay loam, dark reddish brown (5YR 3/2) moist; strong fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and very plastic; many very fine and fine and common medium and coarse roots; common very fine and fine interstitial and few fine tubular pores; many distinct clay films lining pores and on faces of peds; 40 percent gravel and 5 percent cobbles; slightly alkaline (pH 7.4); clear smooth boundary. (5 to 10 cm thick)

Bt2--10 to 20 cm; dark reddish brown (5YR 3/3) very gravelly clay, dark reddish brown (5YR 3/3) moist; strong medium prismatic structure; very hard, very firm, very sticky and very plastic; few fine and medium roots; common very fine and fine interstitial and common fine tubular pores; few distinct clay films lining pores; many pressure faces; 40 percent gravel and 10 percent cobbles; slightly alkaline (pH 7.4); clear wavy boundary. (8 to 15 cm thick)

Bt3--20 to 46 cm; reddish brown (5YR 4/3) very cobbly clay, dark reddish brown (5YR 3/3) moist; strong fine and medium subangular blocky structure; very hard, very firm, very sticky and very plastic; few very fine and fine exped roots; common very fine and fine interstitial and common fine tubular pores; few distinct clay films lining pores; many pressure faces; 20 percent gravel and 30 percent cobbles; slightly alkaline (pH 7.4); abrupt wavy boundary. (18 to 30 cm thick)

R--46 cm; fractured welded tuff.

TYPE LOCATION: Lincoln County, Nevada; in Bunker Peak Wash; approximately 2000 feet south and 500 feet east of the northwest corner of section 35, T. 6 S., R. 70 E.; USGS Bunker Peak 7.5 minute topographic quadrangle; latitude 37 degrees 23 minutes 5 seconds N and longitude 114 degrees 8 minutes 21 seconds W; WGS84 Decimal Degrees 37.3847222 latitude, -114.1391667 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in the moisture control section during the winter and early spring months; moist in some part from July through early September due convective thunderstorms; aridic soil moisture regime that borders on ustic.
Mean annual soil temperature: 8 to 11 degrees C.
Depth to bedrock: 36 to 50 cm.

Particle-size control section - Clay content: Averages 35 to 60 percent.
Rock fragments: 35 to 60 percent. Lithology of fragments is welded tuff.

A horizon
Hue: 5YR or 7.5YR.
Value: 2 or 3 dry.
Chroma: 1 or 2, dry or moist.
Organic matter content: 2 or 3 percent.
Mineralogy: 15 to 24 percent volcanic glass in the 0.02 to 2 mm fraction and averages 0.01 to 0.09 percent Al plus 1/2Fe, extracted by ammonium oxalate.

Bt1 and Bt2 horizons
Hue: 5YR or 7.5YR.
Value: 3 or 4 dry, or moist
Chroma: 2 or 3, dry or moist.
Texture: clay or clay loam.
Modifiers: Very gravelly or very cobbly
Clay content: 35 to 60 percent.
Rock fragments: 35 to 60 percent.
Structure: Prismatic or subangular blocky.
Consistence: Slightly hard to very hard.
Organic matter content: 1 to 3 percent.
Reaction - Neutral or slightly alkaline.
Mineralogy: 15 to 24 percent volcanic glass in the 0.02 to 2 mm fraction and averages 0.1 to 0.2 percent Al plus 1/2Fe, extracted by ammonium oxalate.

Bt3 horizon
Hue: 5YR to 7.5YR.
Value: 3 or 4 dry, or moist.
Chroma: 2 or 3, dry or moist.
Texture: Very gravelly clay or very cobbly clay.
Clay content: 40 to 60 percent.
Rock fragments: 35 to 60 percent.
Organic matter content: 0.5 to 2 percent.
Reaction - Neutral or slightly alkaline.

COMPETING SERIES: These are the Cedaran and Thimble series.

Cedaran soils have an AB horizon and lake ashy modifiers in the argillic horizon.Thimble soils have identifiable secondary carbonates in the particle-size control section.

GEOGRAPHIC SETTING: Acti soils are on mountains. These soils formed in residuum and colluvium derived from welded tuff. Slopes are 15 to 50 percent. Elevations range from 1,450 to 2,050 meters. The climate is dry, sub-humid with cool, moist winters and warm, intermittently moist summers. The mean annual precipitation is 300 to 400 mm, the mean annual air temperature is 7 to 11 degrees C, and the frost-free period is 100 to 130 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Turba and Motoqua soils. Turba and Motoqua soils are loamy-skeletal.

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

USE AND VEGETATION: Acti soils are used for livestock grazing and wildlife habitat. The potential native vegetation is Gamble's oak, Utah serviceberry, Mojave ceanothus, greenleaf manzanita, mountain big sagebrush, muttongrass, prairie junegrass, and some singleleaf pinyon and Utah juniper. This pedon is correlated to ecological site R29XY164NV, Gravelly Clay Slope 12-14 P.Z.

DISTRIBUTION AND EXTENT: Southeastern Nevada. These soils are moderately extensive. MLRA 29.

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

SERIES ESTABLISHED: Lincoln County, Nevada, South Part, 1992.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the surface to 46 cm (A, Bt1, Bt2, and Bt3 horizons).
Argillic horizon - The zone from 5 to 46 cm (Bt1, Bt2, and Bt3 horizons).
Lithic contact - The zone from 46 cm to a lithic contact (R layer).
Particle-size control section - The zone from 5 to 46 cm (Bt1, Bt2, and Bt3 horizons).

The revision of December 2006 updated the taxonomic class from the subgroup of Lithic Argiustolls due to the soil having an ustic moisture regime that borders on aridic.

ADDITIONAL DATA: Previous editors and authors include: DJM/RLB/JVC.

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National Cooperative Soil Survey
U.S.A.