LOCATION MERDEN WYEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, calcareous, mesic Fluvaquentic Endoaquolls
TYPICAL PEDON: Merden loam-on a one percent slope in native range. (Colors are for dry soil unless otherwise stated.)
A1--0 to 10 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; slightly effervescent, calcium carbonate disseminated; strongly alkaline (pH 8.5); clear smooth boundary. (6 to 12 inches thick)
A2--10 to 20 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; very weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; slightly effervescent, calcium carbonate disseminated; strongly alkaline (pH 8.6); clear smooth boundary. (5 to 12 inches thick)
Cg--20 to 60 inches; gray (5Y 5/1) loam, dark gray (5Y 4/1) moist; massive; hard, firm; slightly sticky and slightly plastic; strongly effervescent; calcium carbonate disseminated, and as few fine filaments; moderately alkaline (pH 8.4).
TYPE LOCATION: Laramie County, Wyoming; the NE corner of sec. 9, T. 14 N., R. 60 W. Pine Bluffs Quadrangle. 43 degrees 11 minutes 58 seconds north latitude and 104 degrees 04 minutes 52 seconds west longitude.
RANGE IN CHARACTERISTICS: The mollic epipedon ranges from 10 to 20 inches thick. Depth to the seasonal high water table ranges from 10 to 20 inches. These soils are calcareous throughout. The 10 to 40 inch particle-size control section is typically loam or silty clay loam. Some pedons have lenses of fine sandy loam, very fine sandy loam or sandy clay loam. It averages 18 to 35 percent clay, 10 to 50 percent silt, and more than 15 percent fine sand or coarser but less than 50 percent total sand. The E.C. is typically less than 4 but ranges to 8 in some pedons. The E.S.P. is typically less than 10 but ranges to 15 in some pedons.
The A horizon has hue of 10YR or 2.5Y; value of 3 through 5 dry, 2 or 3 moist; and chroma of 2 or 3. Texture is fine sandy loam, very fine sandy loam, loam, or silty clay loam. Reaction is moderately alkaline through very strongly alkaline.
The Cg horizon has hue of 5Y through 10YR, value of 5 through 8 dry, 4 through 6 moist, and chroma of 1 or 2. Organic carbon content is greater than 0.3 percent between 10 and 50 inches. Redoximorphic features are common in some pedons. Reaction is moderately alkaline or strongly alkaline.
COMPETING SERIES: This is the Voltaire series. The Voltaire soils have more than 35 percent clay in at least half of the particle size control section, typically the upper part.
GEOGRAPHIC SETTING: Merden soils are on low terraces and flood plains. They formed in loamy alluvium. Slopes are 0 to 3 percent. The average annual air temperature is 46 to 50 degrees F., and the average annual precipitation ranges from 13 to 17 inches. Elevations range from 4,700 to 6,500 feet. The frost-free season is from 120 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Alice, Nucla, and Mitchell soils. These soils lack the gleying and high water table associated with the Merden series.
DRAINAGE AND PERMEABILITY: Poorly or somewhat poorly drained; slow runoff; moderate permeability.
USE AND VEGETATION: Some areas are used as hayland or pasture; most areas are used for livestock grazing and wildlife habitat. The typical native plant community is alkali sacaton, inland saltgrass, western wheatgrass, and switchgrass.
DISTRIBUTION AND EXTENT: Southeastern Wyoming. The soils are of limited extent, less than 10,000 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Laramie County, Wyoming (Eastern Part); 1980.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic eppipedon - 0 to 20 inches (A1,A2)
MLRR- G
SIR- WY0081, WY1061
This revision represents a change in classification from fine-loamy, mixed (calcareous) mesic Fluvaquentic Haplaquolls to fine-loamy, mixed (calcareous) mesic Fluventic Endoaquolls.
The superactive cation exchange activity class was added in 03/2003 to the taxonomic classification by the National Soil Survey Center on request of the Lakewood MLRA office, without review of the soil series property data. The remainder of this document has not been updated.