LOCATION BLACKTANK AZ

Tentative Series
JMH/HAH/NMS
05/2021

BLACKTANK SERIES

The Blacktank series consists of very deep, somewhat excessively drained soils that formed in alluvium from tephra. Blacktank soils are on alluvial fans, and washes. Slopes range from 1 to 5 percent. The mean annual precipitation is about 7 inches and the mean annual air temperature is about 52 degrees F.

TAXONOMIC CLASS: Ashy, glassy, mesic Sodic Haplocambids

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

A1--0 to 1 inch (0 to 3 cm); brown (7.5YR 5/2) gravelly sandy clay loam, dusky red (7.5R 3/2), moist; 30 percent clay; moderate coarse granular structure; slightly hard, friable, very sticky, moderately plastic; few fine tubular pores; 10 percent carbonate, finely disseminated throughout; and 25 percent, nonflat, angular, indurated cinder gravels; very slightly effervescent; slightly alkaline, pH 7.8; clear smooth boundary.

A2--1 to 6 inches (3 to 15 cm); brown (7.5YR 5/2) gravelly clay loam, dusky red (7.5R 3/2), moist; 28 percent clay; moderate coarse granular structure; slightly hard, friable, moderately sticky, moderately plastic; few very fine roots throughout; few fine tubular pores; 15 percent, nonflat, angular, indurated cinder gravels; very slightly effervescent; slightly alkaline, pH 7.8; gradual smooth boundary.

Bw--6 to 19 inches (15 to 48 cm); brown (7.5YR 5/3) silty clay loam, dusky red (7.5R 3/2), moist; 28 percent clay; weak coarse subangular blocky structure; moderately hard, friable, moderately sticky, moderately plastic; common very fine roots throughout; 10 percent, nonflat, angular, indurated cinder gravels; very slightly effervescent; moderately alkaline, pH 8.0; gradual smooth boundary.

Bk--19 to 40 inches (48 to 102 cm); light brown (7.5YR 6/3) gravelly sandy clay loam, brown (7.5YR 4/2), moist; 26 percent clay; weak medium subangular blocky structure; moderately hard, friable, moderately sticky, moderately plastic; very fine roots throughout and fine roots throughout; 15 percent carbonate, finely disseminated throughout; 25 percent, nonflat, angular, indurated cinders gravels; strongly effervescent; strongly alkaline, pH 8.8; clear smooth boundary.

C1--40 to 47 inches (102 to 119 cm); 20 percent pinkish white (7.5YR 8/2) and 80 percent gray (7.5YR 5/1) very gravelly coarse sand, 20 percent light brown (7.5YR 6/3) and 80 percent very dark gray (7.5YR 3/1), moist; 4 percent clay; massive; loose, loose, nonsticky, nonplastic; 45 percent, nonflat, angular, indurated cinder gravels; slightly effervescent; moderately alkaline, pH 8.2; abrupt smooth boundary.

C2--47 to 60 inches (119 to 152 cm); dark gray (7.5YR 4/1) extremely gravelly coarse sand, very dark gray (7.5YR 3/1), moist; 1 percent clay; single grain; loose, loose, nonsticky, nonplastic; 2 percent medium irregular very strongly cemented silica masses; 95 percent, nonflat, angular, indurated cinder gravels; very slightly effervescent; moderately alkaline, pH 8.2; clear smooth boundary.

TYPE LOCATION:
Coconino County, Arizona; Geographic Coordinate System: 35 37' 50.5'' north, 111 34' 53.9.6'' west NAD83.

RANGE IN CHARACTERISTICS:
Soil moisture: Intermittently moist in some part of the soil moisture control section during July - September. Driest during May and June. Typic Aridic soil moisture regime.

Soil Temperature: 52 to 56 degrees Fahrenheit (11.1 to 13.3 degrees Celsius)
Particle-size control section (weighted average)
Clay content: 12 to 18 percent
Rock Fragments: 35 to 55 percent cinders
Volcanic Glass: 30 to 40 percent

Depth to cambic horizon: 2 to 19 inches (5 to 47 cm)

A Horizon
Hue: 7.5YR, 10YR
Value: 3 to 5 dry, 2.5 to 4 moist
Chroma: 1 to 3, dry or moist
Texture: sandy loam
Clay: 8 to 14 percent
Calcium carbonate equivalent: 5 to 10 percent
Rock fragments: 20 to 60 percent cinders
Reaction: slightly alkaline to moderately alkaline

Bk Horizons
Hue: 7.5YR, 10YR
Value: 4 to 7 dry, 4 to 6 moist
Chroma: 2 to 4, dry or moist
Texture: sandy loam, sandy clay loam, loam
Clay: 18 to 30 percent
Calcium carbonate equivalent: 5 to 15 percent
Rock fragments: 35 to 60 percent cinders
Reaction: moderately alkaline to strongly alkaline

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Blacktank soils are on alluvial fans of cinders and ash at elevations of 4,662 to 5,705 feet (1,421 to 1,739 meters). Slopes range from 0 to 5 percent. These soils formed in alluvium from tephra deposits. The mean annual precipitation is 6 to 10 inches (152 to 254 millimeters) and occurs as thunderstorms during July to September and as gentle rains and snowfall during December and January. The mean annual air temperature is 54 to 57 degrees Fahrenheit (12.2 to 13.9 degrees Celsius). The frost-free period is 150 to 180 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Nalaki (AZ), Lomaki (AZ), and Tuweep (AZ), soils. Tuweep soils form in basalt residuum have calcic and argillic horizons, are moderately deep, and have more than 14 percent clay and less than 35 percent gravel fragments in the particle size control section. Nalaki soils form in tephra residuum and are very shallow and shallow to bedrock to duripan, and have less than 27 percent clay in the particle size control section. Lomaki soils form in tephra residuum and are very deep, and have less than 27 percent clay in the particle size control section.

DRAINAGE AND PERMEABILITY: Somewhat excessively drained; low runoff; moderate or moderately rapid permeability.

USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Vegetation includes galleta, broom snakeweed, black grama, and fourwing saltbush.

DISTRIBUTION AND EXTENT: Northern Arizona. Blacktank soils are of moderate extent. This soil is named after the tank near the type location. MLRA 35 Land Resource Unit 35.2.

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

SERIES ESTABLISHED: Coconino County, Arizona; Bighawk Valley Soil Survey Update Project, AZ, 2016

REMARKS: Diagnostic horizons and features recognized in this pedon are:

The epipedon is neither mollic nor ochric because rock structure exists in surface fragments and within the upper two horizons.

Cambic horizon - the zone from 2 to 19 inches (5 to 47 cm) (Bk1 and Bk2 horizons)

Volcanic glass - exceeds 30 percent in mineral class control section

Particle size control section - the zone from 10 to 40 inches (25 to 100 cm) (Bk horizons)

Classified according to Keys to Soil Taxonomy, Twelfth Edition, 2014

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National Cooperative Soil Survey
U.S.A.