LOCATION DAWNY WYInactive Series
TAXONOMIC CLASS: Coarse-loamy, mixed, active, mesic Pachic Argiustolls
TYPICAL PEDON: Dawny fine sandy loam-on a northwest facing slope of one percent; utilized as rangeland. (Colors are for dry soil unless otherwise stated.
A--0 to 5 inches; grayish brown (10YR 5/2) fine sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium and fine granular structure; soft, friable, nonsticky and nonplastic; many fine and very fine roots; slightly acid (pH 6.2); clear smooth boundary. (5 to 14 inches thick).
AB--5 to 11 inches; brown (10YR 5/3) fine sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium and fine granular structure parting to weak fine subangular blocky; soft, friable, nonsticky and nonplastic; common fine and very fine roots; slightly acid (pH 6.2); clear wavy boundary. (0 to 13 inches thick)
BA--11 to 18 inches; brown (10YR 5/3) fine sandy loam, dark brown (10YR 3/3) moist; weak medium and fine subangular blocky structure; soft, friable, nonsticky and nonplastic plastic; common fine and very fine roots; slightly acid (pH 6.4); clear wavy boundary; (0 to 7 inches thick)
Bt1--18 to 31 inches; brown (10YR 5/3) fine sandy loam, dark brown (10YR 3/3) moist; weak fine prismatic structure parting to moderate fine subangular blocky; soft, friable, nonsticky and nonplastic; common fine and very fine roots; many thin clay films bridging sand grains and lining soil pores; neutral (pH 6.8); clear wavy boundary.
Bt2--31 to 43 inches; pale brown (10YR 6/3) fine sandy loam, brown to dark brown (10YR 4/3) moist; weak medium prismatic structure parting to moderate medium and fine subangular blocky; slightly hard, friable, nonsticky and slightly plastic; few fine roots; many thin clay films bridging sand grains, few thin clay films coating ped faces; neutral (pH 7.0); clear wavy boundary. (Combined thickness of Bt horizon is 13 to 25 inches)
2 - Dawny Series
C--43 to 60 inches; pale brown (10YR 6/3) loamy sand, brown to dark brown (10YR 4/3) moist; massive; soft, friable, nonsticky and nonplastic; few fine roots; mildly alkaline (pH 7.4).
TYPE LOCATION: Niobrara County, Wyoming; about 1,620 feet south and 780 feet east of the northwest corner of sec. 8, T. 31 N., R. 61 W.
RANGE IN CHARACTERISTICS: Dawny soils are typically noncalcareous, but some pedons contain few fine masses of calcium carbonate below 50 inches. Depth to the base of the mollic epipedon ranges from 25 to 38 inches. Bedrock is deeper than 60 inches. Coarse fragments are typically less than 5 percent but range from 0 to 15 percent. The soil is dry in the moisture control section more than half the time cumulative that the soil temperature at a depth of 20 inches is 41 degrees F., which occurs about April 20-27, but is dry in all parts of the moisture control section for at least 60 consecutive days from July 15 to October 25 and for at least 90 cumulative days during this period. The mean annual soil temperature is 47 to 51 degrees F., and the soil temperature at a depth of 20 inches is 41 degrees F. or more for 175 to 192 days.
The A horizon has hue of 10YR or 2.5Y, value of 4 or 5 dry and 2 or 3 moist, and chroma of 2 or 3. It is neutral or slightly acid.
An AB or BA horizon is present in most pedons. It has the same range in characteristics as the A horizon.
The Bt horizon has hue of 10YR or 2.5Y, value of 5 or 6 dry and 3 or 4 moist, and chroma of 2 or 3. Textures are fine sandy loam or sandy loam with 10 to 18 percent clay and 60 to 75 percent fine and coarser sand. Structure is typically subangular blocky or prismatic. It is neutral or mildly alkaline.
The C horizon has hue of 10YR or 2.5Y, value of 6 or 7 moist and 4 or 5 dry, and chroma of 2 or 3. Textures are loamy sand, loamy fine sand, loamy very fine sand, or fine sandy loam with less than 15 percent clay. It is neutral or mildly alkaline.
COMPETING SERIES: There are no other series in this taxonomic class.
GEOGRAPHIC SETTING: Dawny soils are on valley filling uplands, upland basins, and relict eolian surfaces. They formed in alluvial and eolian sediments derived from noncalcareous fine grained sandstone. Slopes are 0 to 10 percent. Elevations are 4,800 to 5,500 feet. The mean annual precipitation ranges from 15 to 17 inches, half of which falls as rain and snow in April, May, and June. The mean annual temperature ranges from 43 to 49 degrees F. The frost-free season is 105 to 130 days.
3 - Dawny Series
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Jayem, Moskee, Noden, Tracylee (P), and Vetal soils. Moskee, Noden, and Tracylee soils have fine-loamy particle-size control sections. In addition, Moskee soils have secondary accumulations of calcium carbonate. Jayem and Vetal soils lack argillic horizons. Also, Jayem soils have mollic epipedons less than 20 inches thick.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderately rapid permeability.
USE AND VEGETATION: These soils are utilized for grazing by domestic livestock, wildlife habitat, and for dryland and irrigated cropland and hayland. The native vegetation is needleandthread, threadleaf sedge, prairie junegrass, prairie sandreed, and silver sagebrush. Wheat, barley, alfalfa, oats, and short season corn are the principal crops grown under cultivation.
DISTRIBUTION AND EXTENT: Dawny soils occur in east central Wyoming. The series is of limited extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES PROPOSED: Niobrara County, Wyoming; 1986.