LOCATION CHARCOAL ID
Tentative Series
CBR/DJP
04/2020
CHARCOAL SERIES
The Charcoal series consists of very deep, excessively drained soils that formed in alluvium or till. These soils are on stream terraces, alluvial fans, or moraines. Slopes are 0 to 20 percent. Mean annual precipitation is about 500 mm, and mean annual air temperature is about 2 degrees C.
TAXONOMIC CLASS: Sandy-skeletal, mixed Xeric Haplocryolls
TYPICAL PEDON: Charcoal gravelly loam in rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 8 cm; dark grayish brown (10YR 4/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; common very fine and fine roots; many irregular pores; 30 percent gravel; moderately acid (pH 5.8); abrupt smooth boundary.
Bw--8 to 31 cm; brown (10YR 4/3) very gravelly silt loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; many very fine and common fine, medium, and coarse roots; many irregular pores; 45 percent gravel; moderately acid (pH 5.8); clear wavy boundary.
C1--31 to 59 cm; light yellowish brown (10YR 6/4) extremely gravelly coarse sand, dark yellowish brown (10YR 4/4) moist; common very fine and few fine roots; 60 percent gravel, 20 percent cobbles; moderately acid (pH 5.6); gradual wavy boundary.
C2--59 to 150 cm; very pale brown (10YR 7/3) extremely gravelly coarse sand, pale brown (10YR 6/3) moist; 60 percent gravel, 20 percent cobbles; moderately acid (pH 5.6).
TYPE LOCATION: Custer County, Idaho; USGS topographic quadrangle Big Black Dome; latitude 43.76702 degrees north, longitude 113.93329 degrees west, datum WGS84.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--2.1 to 3.9 degrees C
Thickness of mollic epipedon--29 to 38 cm
Depth to sand and gravel--22 to 60 cm
Particle-size control section (weighted averages)
Clay content--4 to 8 percent
Total rock fragments--65 to 80 to percent
A horizon
Hue--7.5YR or 10YR
Value--4 or 5 dry, 2 to 3 moist
Chroma--2 or 3 dry, 1 or 2 moist
Texture (less than 2 mm fraction)--silt loam or loam
Clay content--10 to 18 percent
Rock fragments--15 to 30 percent gravel
Reaction--pH 5.8 to 6.4
Thickness--8 to 30 cm
Bw horizon (when present)
Hue--7.5YR or 10YR
Chroma--2 to 4 moist
Texture (less than 2 mm fraction)--silt loam or loam
Clay content--14 to 22 percent
Rock fragments--45 to 55 percent - 45 to 55 percent gravel, 0 to 5 percent cobbles
Reaction--pH 5.4 to 6.0
Thickness--0 to 31 cm
C horizons
Value--6 or 7 dry, 4 to 6 moist
Chroma--3 or 4
Texture (less than 2 mm fraction)--sand, coarse sand, loamy sand
Clay content--1 to 5
Rock fragments--75 to 85 percent - 70 to 80 percent gravel, 5 to 15 percent cobbles
Reaction--pH 5.4 to 6.6
COMPETING SERIES:
Langer (ID) --soils have a cambic horizon
Wiggleton (ID) --soils have secondary calcium carbonate accumulations
GEOGRAPHIC SETTING:
Landform-- stream terraces, alluvial fans, or moraines
Elevation--2,080 to 2,800 meters
Slope--0 to 20 percent
Parent material--alluvium or till
Mean annual precipitation--450 to 825 mm
Mean annual air temperature--1.1 to 2.9 degrees C
Frost-free period--30 to 60 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Excessively drained, 5 to 15 um/sec in the upper part and 150 to 700 um/sec in the lower part
USE AND VEGETATION: Charcoal soils are primarily used for grazing. The potential native vegetation early sagebrush, mountain big sagebrush, and Idaho fescue.
DISTRIBUTION AND EXTENT: Charcoal soils are of moderate extent in southeastern Idaho; MLRAs 12 and 43B.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Custer County, Idaho, 2020. Charcoal series is derived from a nearby stream.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Mollic epipedon--0 to 31 cm (A and Bw horizons)
Particle-size control section--25 to 100 cm
Charcoal soils have a cryic temperature regime and a xeric moisture regime.
Taxonomic version: Twelfth Edition, 2014
National Cooperative Soil Survey
U.S.A.