LOCATION RALLOD WY+MTEstablished Series
TAXONOMIC CLASS: Clayey, smectitic, frigid, shallow Ustic Natrargids
TYPICAL PEDON: Rallod fine sandy loam-rangeland. (Colors are for dry soil unless otherwise stated.)
A1--0 to 4 inches; pale brown (10YR 6/3) very fine sandy loam, brown (10YR 4/3) moist; weak very fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine, fine, and medium roots; many very fine vesicular pores; moderately alkaline (pH 8.2); clear smooth boundary.
A2--4 to 7 inches; brown (10YR 5/3) loam, brown (10YR 4/3) moist; weak thin platy structure parting to moderate very fine granular; soft, very friable, slightly sticky and plastic; common very fine, fine, and medium roots; strongly alkaline (pH 8.6); abrupt smooth boundary. (Combined thickness of the A horizon is 2 to 8 inches)
Btn--7 to 12 inches; reddish brown (5YR 5/4) sandy clay, reddish brown (5YR 4/4) moist; strong medium columnar structure parting to moderate coarse angular blocky; extremely hard, extremely firm, very sticky and very plastic; few very fine, fine, and medium roots; continuous, thick clay films on faces of peds; slightly effervescent, carbonates disseminated; strongly alkaline (pH 8.8); clear wavy boundary.
Btnk--12 to 14 inches; brown (7.5YR 5/4) sandy clay, yellowish brown (10YR 5/4) moist; strong medium prismatic structure parting to moderate coarse angular blocky; extremely hard, extremely firm, very sticky and very plastic; few very fine, fine, and medium roots; continuous thick clay films on faces of peds; strongly effervescent, carbonates disseminated and as few small and medium soft masses and seams; very strongly alkaline (pH 9.2); clear broken boundary. (Combined thickness of the Btn and Btnk horizon is 5 to 10 inches)
Bk--14 to 18 inches; brown (7.5YR 5/4) sandy clay loam, light olive brown 2.5Y 5/4) moist; weak coarse angular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine, fine, and medium roots; strongly effervescent, carbonates disseminated and as few medium seams; strongly alkaline (pH 8.6); abrupt wavy boundary. (0 to 5 inches thick)
Cr--18 to 60 inches; soft, clayey sandstone interbedded with sodic shale.
TYPE LOCATION: Fremont County, Wyoming; about 1,100 feet east and 250 feet north of the SE corner of sec. 31, T. 34 N., R. 97 W.
RANGE IN CHARACTERISTICS: Depth to the paralithic contact and interbedded shale and sandstone ranges from 8 to 20 inches. Depth to continuous horizons of carbonate accumulation is 6 to 14 inches. The mean annual soil temperature is 36 to 46 degrees F., and the mean summer soil temperature is 59 to 62 degrees F. Coarse fragments are absent throughout the profile. Organic carbon content ranges from 1 to 3 percent in the surface and decreases regularly with depth. Colors are quite variable throughout the profile due to the variegated shale and sandstone parent material.
The A horizon has hue of 2.5Y through 5YR, value of 4 through 6 dry, 3 or 4 moist, and chroma of 2 through 6. EC ranges from 0 to 2 mmhos. Reaction is mildly or moderately alkaline. An E horizon may be present in some pedons.
The Btn and Btnk horizons have hue of 10YR through 2.5YR, value of 3 through 6 dry, 3 through 5 moist, and chroma of 2 through 4. Texture is typically clay or sandy clay, but clay ranges from 35 to 55 percent, silt from 0 to 50 percent, and sand from 15 to 65 percent. Exchangeable sodium ranges from 15 to 35 percent. Reaction is strongly or very strongly alkaline.
The Bk horizon, when present, has hue of 2.5Y through 2.5YR, value of 3 through 6 dry, 2 through 5 moist, and chroma of 2 through 6. Texture is sandy clay, clay, clay loam, or sandy clay loam with clay ranging from 27 to 45 percent. EC ranges from 2 to 8 mmhos. Exchangeable sodium ranges from 15 to 30 percent. Reaction is strongly or very strongly alkaline. A thin C horizon may be present in some pedons.
COMPETING SERIES: There are no other series in this class, but the Mudray and Youjay soils are similar. Both soils have less than one percent organic carbon in the upper 15 inches when averaged. Also Mudray soils have a mesic temperature regime.
GEOGRAPHIC SETTING: Rallod soils are on rolling hillslope positions and ridge crests. These soils formed in residuum and colluvium from sodic shale and sandstone. Slopes are 3 to 30 percent. Elevations range from 6,000 to 7,300 feet in Wyoming and down to 3,000 feet in Montana. The climate is cool, semiarid with moist spring and dry summers and fall. The mean annual precipitation is about 11 inches and ranges from 9 to 14 inches of which about half falls as snow or rain in April, May, and early June. The mean annual temperature is about 41 degrees F. but ranges from 36 to 44 degrees F. The frost-free season is estimated to be 80 to 110 days; but, because of elevation, aspect, and air drainage, frost may occur at any time.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Absher, Abston, Seaverson, and Tisworth soils. Absher, Abston, and Tisworth soils are moderately deep or deep and occur more on footslopes and toeslopes downslope from the Rallod soils. Seaverson soils do not have natric horizons and occur on the more unstable hillslope positions.
DRAINAGE AND PERMEABILITY: Well drained; medium or rapid runoff; very slow permeability.
USE AND VEGETATION: Rangeland and wildlife habitat. Native vegetation is thickspike wheatgrass, bud sage, Indian ricegrass, and Gardner saltbush.
DISTRIBUTION AND EXTENT: Western Wyoming and south-central Montana. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Fremont County, Wyoming, East Part; 1984.