LOCATION ABSTON WYEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Ustic Natrargids
TYPICAL PEDON: Abston sandy loam-rangeland. (Colors are for dry soil unless otherwise stated).
A--0 to 1 inch; yellowish brown (10YR 5/4) sandy loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium granular structure; soft, very friable, nonsticky and slightly plastic; many very fine, fine, and medium roots; neutral (pH 6.8); abrupt smooth boundary. (1 to 3 inches thick)
E--1 to 3 inches; light gray (10YR 7/1) sandy loam, dark grayish brown (10YR 4/2) moist; massive; soft, very friable, slightly sticky and slightly plastic; many very fine and few medium roots; vesicular pores; neutral (pH 7.0); abrupt smooth boundary. (0 to 3 inches thick)
Bt--3 to 5 inches; brown (10YR 5/3) clay, dark brown (10YR 4/3) moist; strong fine columnar structure parting to strong fine angular blocky; hard, firm, sticky and plastic; many very fine, few medium roots; thick, continuous clay films on all faces of peds; mildly alkaline (pH 7.4); clear wavy boundary.
Btn1--5 to 10 inches; grayish brown (10YR 5/2) clay, dark grayish brown (10YR 4/2) moist; strong fine prismatic structure parting to strong fine angular blocky; hard, firm, sticky and plastic; few fine and medium roots; thick, continuous clay films on all faces of peds; strongly alkaline (pH 9.0); clear wavy boundary.
Btn2--10 to 17 inches; grayish brown (10YR 5/2) sandy clay loam, dark grayish brown (10YR 4/2) moist; moderate fine angular blocky structure; hard, firm, sticky and plastic; very few medium roots; thin, discontinuous clay films on vertical faces of peds; slightly effervescent; very strongly alkaline (pH 9.2); clear wavy boundary. (Combined thickness of the Btn horizons is 11 to 22 inches thick.)
Bk1--17 to 28 inches; brown (10YR 5/3) sandy clay loam, dark grayish brown (10YR 4/2) moist; massive; hard, firm, slightly sticky and slightly plastic; violently effervescent; many fine seams of secondary calcium carbonate; very strongly alkaline (pH 9.4); gradual wavy boundary. (8 to 14 inches thick)
Bk2--28 to 34 inches; light brownish gray (10YR 6/2) sandy clay loam, dark grayish brown (10YR 4/2) moist; massive; hard, firm, slightly sticky and slightly plastic; violently effervescent; many medium soft masses and seams of secondary calcium carbonate; violently effervescent, very strongly alkaline (pH 9.4); gradual wavy boundary. (5 to 10 inches thick)
Cr--34 to 60 inches; soft, calcareous sodic shale.
TYPE LOCATION: Sublette County, Wyoming; Blue Rim Area, SW1/4, SW1/4 of sec. 19, T. 30 N., R. 108 W.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 35 to 46 degrees F., and the mean summer soil temperature is 59 to 62 degrees F. Depth to bedrock and the paralithic contact is 20 to 40 inches. Depth to calcareous materials is 6 to 20 inches. Coarse fragments range from 0 to 20 percent throughout the whole soil and consist of 1/2- to 1-inch angular shale.
The A horizon has hue of 2.5Y or 10YR, value of 4 through 7 dry, 3 through 5 moist, and chroma of 2 through 4 dry and moist. Matrix texture is typically sandy loam but ranges from sandy loam to very fine sandy loam or loam. Reaction is neutral or mildly alkaline.
The Btn horizon has hue of 2.5Y through 10YR, value of 4 through 6 dry, 3 through 5 moist, and chroma of 2 through 4 dry and moist. The matrix texture of the upper Btn is silty clay, sandy clay, clay, or clay loam averaging 35 to 50 percent clay. The reaction of the upper Btn is mildly alkaline through strongly alkaline. Matrix texture of the lower Btn is sandy clay loam, clay loam, sandy clay, silty clay, or clay. Reaction of the lower Btn is strongly alkaline or very strongly alkaline unless buffered by salts. ESP is 15 to 30.
The Bk horizon has hue of 5Y through 10YR, value of 5 through 7 dry, 4 through 6 moist, and chroma of 2 through 4. Matrix texture is loam, sandy clay loam, clay loam, silty clay loam, sandy clay, or clay. Reaction is moderately through very strongly alkaline unless buffered by salts. ESP is 15 to 30.
COMPETING SERIES: These are the Absher, Creed, Elloam, Gerdrum, Giarc(T), Loburn, Obadia(T), Oburn, Spicerton, Thoeny, and Weingart series. All of these series except Weingart are very deep. Weingart soils are similar but have pedogenic accumulations of gypsum.
GEOGRAPHIC SETTING: Abston soils are on hillslopes and terrace escarpments. These soils formed in residuum and colluvial slopewash weathered from soft, strongly sodic shales. Elevation is 6,000 to 7,800 feet. The mean annual temperature is 34 to 45 degrees F. The mean annual precipitation is about 9 to 14 inches of which about half falls as snow or rain in April, May, and early June. The frost-free season is about 80 to 110 days but frost may occur in any month.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bluerim and Milren soils. Bluerim soils have fine-loamy argillic horizons. Milren soils have argillic horizons and are deep.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; slow permeability.
USE AND VEGETATION: Used for grazing by livestock and wildlife. Vegetation is big sagebrush, low sage, thickspike wheatgrass, Sandberg bluegrass, and Indian ricegrass.
DISTRIBUTION AND EXTENT: Southern Wyoming. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Fremont County, Wyoming, East Part; 1984.
REMARKS: Diagnostic horizons and features recognized in this pedon are: Ochric epipedon--0 to 1 inch (A).
Natric horizon--5 to 17 inches (Btn1,Btn2).
Paralithic contact--34 inches (Cr).
Borollic feature--0.5 to 1.0 percent organic carbon in the A horizon and a frigid temperature regime meet the requirements for the borollic subgroup.