LOCATION AVENT WY
Tentative Series
IRD. DEW-JCK
03/2017
AVENT SERIES
The Avent series consist of very deep, moderately drained soils that formed in alluvium. These soils are on stream terraces and flood-plain steps. Slopes range from 0 to 4 percent. Mean annual precipitation is about 191 mm, and mean annual air temperature is about 7 degrees C.
TAXONOMIC CLASS: Fine, smectitic, mesic Aquic Haplargids
TYPICAL PEDON: Avent sandy clay loam, 2 percent slope in rangeland at an elevation of 1,467 meters. (Colors are for moist soil unless otherwise noted.)
A--0 to 8 cm; very dark grayish brown (10YR 3/2) sandy clay loam, dark grayish brown (10YR 4/2) dry; weak fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and common fine roots throughout; neutral (pH 6.6); clear smooth boundary. (5 to 20 cm thick)
Btkz--8 to 37 cm; dark grayish brown (10YR 4/2) clay loam, grayish brown (10YR 5/2) dry; moderate medium subangular blocky structure; moderately hard, firm, very sticky and very plastic; common very fine and few fine roots throughout, common very fine dendritic tubular pores; 20 percent prominent clay films on all faces of peds; 8 percent fine irregular calcium carbonate masses and 4 percent fine irregular salt masses in the matrix; 2 percent 10YR 2/1 manganese masses, 20 percent 5YR 5/6 oxidized iron masses, 5 percent 5Y 6/1 iron depletions; strongly effervescent; moderately alkaline (pH 8.0); clear smooth boundary. (10 to 35 cm thick)
Bkz--37 to 57 cm; dark grayish brown (10YR 4/2) sandy clay loam, grayish brown (10YR 5/2) dry; moderate medium subangular blocky structure; moderately hard, firm, very sticky and very plastic; few very fine roots throughout, few very fine dendritic tubular pores; 4 percent fine irregular calcium carbonate masses and 4 percent fine irregular salt masses in the matrix; 2 percent 10YR 2/1 manganese masses, 15 percent 5YR 3/4 oxidized iron masses, 20 percent 2.5Y 5/1 iron depletions; violently effervescent; moderately alkaline (pH 8.2); gradual smooth boundary. (15 to 40 cm thick)
C--57 to 109 cm; dark grayish brown (10YR 4/2) sandy loam, grayish brown (10YR 5/2) dry; massive; soft, very friable, slightly sticky and slightly plastic; 5 percent 5YR 3/4 oxidized iron masses, 25 percent 5Y 5/1 iron depletions; slightly effervescent; slightly alkaline (pH 7.8); gradual smooth boundary. (0 to 54 cm thick)
Cg--109 to 200 cm; dark greenish gray (10Y 4/1) very gravelly sandy loam, greenish gray (10Y 5/1) dry; single grain; loose, nonsticky and nonplastic; 2 percent 5YR 3/4 oxidized iron masses, 30 percent 5Y 5/1 iron depletions; 35 percent gravel; slightly effervescent; slightly alkaline (pH 7.8).
TYPE LOCATION: Park County Wyoming; 265 meters south and 1 meter east of the northwest corner of section 23, T. 51N., R. 98W.; YU Bench NE USGS quadrangle; latitude 44 degrees 23 minutes 0.58 seconds N. and longitude 108 degrees 36 minute 50.64 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 8 to 10 degrees C
Depth to seasonal high water table - 90 to 180 cm
Depth to seasonal high, irrigation-induced water table - 30 to 45 cm
Rock fragments - 0 to 15 percent gravel in the particle-size control section; 15 to 60 percent in the lower part of the subsoil
A horizon
Hue: 7.5YR to 2.5Y
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 or 3
Texture: sandy clay loam, clay loam, loam or sandy loam
Clay content: 18 to 28 percent
Rock fragments: 0 to 15 percent gravels
Electrical conductivity: 4 to 8 mmhos/cm
Reaction: 6.6 to 7.8
Btkz horizon
Hue: 7.5YR to 2.5Y
Value: 4, 5 or 6 dry; 3, 4 or 5 moist
Chroma: 2, 3 or 4
Texture: clay loam, sandy clay, silty clay loam or silty clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 15 percent gravels
Calcium carbonate equivalent: 5 to 15 percent
Electrical conductivity: 8 to 16 mmhos/cm
Reaction: 7.6 to 8.2
Bkz horizon
Hue: 7.5YR to 2.5Y
Value: 4, 5 or 6 dry; 3, 4 or 5 moist
Chroma: 2, 3 or 4
Texture: sandy clay loam, clay loam or loam
Clay content: 20 to 35 percent
Rock fragments: 0 to 15 percent gravel
Calcium carbonate equivalent: 5 to 15 percent
Electrical conductivity: 8 to 16 mmhos/cm
Reaction: 7.6 to 8.2
C horizon
Hue: 7.5YR to 2.5Y
Value: 4, 5 or 6 dry; 3, 4 or 5 moist
Chroma: 2, 3 or 4
Texture: sandy loam, fine sandy loam, or loam
Clay content: 10 to 18 percent
Rock fragments: 15 to 60 percent gravels
Electrical conductivity: 4 to 8 mmhos/cm
Reaction: 7.4 to 8.0
Cg horizon
Hue: 5Y to 10Y
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 1 or 2
Texture: sandy loam, fine sandy loam, or loam
Clay content: 10 to 18 percent
Rock fragments: 15 to 60 percent gravels
Electrical conductivity: 4 to 8 mmhos/cm
Reaction: 7.4 to 8.0
COMPETING SERIES:
No competing soil series.
GEOGRAPHIC SETTING:
Landform - stream terraces and flood-plain steps
Elevation - 1,085 - 1,500 meters
Slope - 0 to 4 percent slopes
Parent material - alluvium
Mean annual precipitation - 127 to 229 mm
Mean annual air temperature - 6 to 8 degrees C
Frost-free period - 110 to 150 days
GEOGRAPHICALLY ASSOCIATED SOILS: None
DRAINAGE AND PERMEABILITY: Moderately well drained; moderate to moderately slow permeability above the C horizon and moderately rapid permeability below.
USE AND VEGETATION: Avent soils are primarily used for livestock grazing and wildlife habitat. Native vegetation is alkali sacaton, Sandberg bluegrass, Nuttall's alkaligrass, creeping bentgrass, mountain rush, and hydrophilic sedges.
DISTRIBUTION AND EXTENT: Avent soils are of small extent in northwestern Wyoming. MLRA 32.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Park County, Wyoming; 2016. The name is taken from a local historic school.
REMARKS:
Ochric epipedon - from 0 to 8 cm (A horizon)
Argillic horizon - from 8 to 37 cm (Btkz horizon)
Redoximorphic concentrations - from 8 to 200 cm (Btkz, Bkz, C and Cg horizons)
Redoximorphic depletions - from 37 to 200 cm (Bkz, C and Cg horizons)
Particle-size control section - from 8 to 37 cm (Btkz horizon)
Avent soils have a mesic temperature regime and an aridic moisture regime.
National Cooperative Soil Survey
U.S.A.