LOCATION ARCHIN SD+MT WYEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Aridic Natrustalfs
TYPICAL PEDON: Archin fine sandy loam - on a plane slope of less than 1 percent in native range. When described the soil was dry to 60 inches. (Colors are for dry soil unless otherwise stated.)
A--0 to 4 inches; grayish brown (10YR 5/2) fine sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; slightly hard, very friable; many fine roots; slightly acid; clear wavy boundary. (3 to 6 inches thick)
E--4 to 6 inches; light brownish gray (10YR 6/2) loam, dark grayish brown (10YR 4/2) moist; weak medium platy structure parting to weak medium and fine subangular blocky; soft, very friable; common fine roots; slightly acid; abrupt wavy boundary. (2 to 8 inches thick)
Btn1--6 to 8 inches; grayish brown (2.5Y 5/2) loam, dark grayish brown (2.5Y 4/2) moist; moderate medium columnar structure parting to strong medium subangular blocky; extremely hard, friable, slightly sticky, and plastic; light brownish gray (10YR 6/2) coatings on the tops of the columns; common fine compressed roots; shiny coats on the faces of peds; slightly acid; abrupt wavy boundary.
Btn2--8 to 17 inches; grayish brown (2.5Y 5/2) loam, dark grayish brown (2.5Y 4/2) moist; weak medium prismatic structure parting to moderate medium and fine subangular blocky; extremely hard, friable, sticky, and plastic; common fine compressed roots; shiny coats on faces of peds; slightly acid; abrupt wavy boundary. (Combined Btn horizons 7 to 12 inches thick)
Bkz--17 to 28 inches; light brownish gray (2.5Y 6/2) loam, dark grayish brown (2.5Y 4/2) moist; moderate coarse prismatic structure parting to moderate coarse and medium subangular blocky; very hard, friable, slightly sticky, and plastic; shiny coats on the faces of the peds; few fine compressed roots; common fine accumulations of carbonate; common fine nests of gypsum crystals and other salts; strong effervescence; moderately alkaline; gradual wavy boundary. (6 to 14 inches thick)
C1--28 to 48 inches; light brownish gray (2.5Y 6/2) loam, dark grayish brown (2.5Y 4/2) moist; massive; hard, friable; slightly sticky and slightly plastic; very few fine roots; strong effervescence; strongly alkaline; diffuse boundary.
C2--48 to 60 inches; light brownish gray (2.5Y 6/2) loam, grayish brown (2.5Y 5/2) moist; massive; hard, friable, slightly sticky and slightly plastic; common very fine nests of gypsum crystals and other salts; strong effervescence; moderately alkaline.
TYPE LOCATION: Harding County, South Dakota; about 13 miles north of Camp Crook; 1760 feet south and 1050 feet west of the northeast corner of sec. 3, T. 20 N., R. 1 E.
RANGE IN CHARACTERISTICS: The depth to soft bedrock typically is below 60 inches. Some pedons have buried horizons at depths below 30 inches. Visible salts are between depths of 16 and 24 inches. The SAR ranges from 13 to 20 in the natric horizon. Depth to carbonates ranges from 10 to 30 inches. The combined A and E horizon thickness ranges from 5 to 14 inches.
The A horizon has hue of 10YR or 2.5Y, value of 4 to 6 and 3 or 4 moist, and chroma of 1 to 4. It is fine sandy loam, very fine sandy loam, loam, or silt loam and ranges from moderately acid to neutral.
The E horizon has hue of 10YR or 2.5Y; value of 5 to 7, 3 to 5 moist; and chroma of 1 to 4. It is fine sandy loam, very fine sand loam, loam, silt loam, or loamy fine sand and ranges from moderately acid to neutral.
The Btn horizon has hue of 10YR or 2.5Y, value of 5 or 6 and 4 or 5 moist, and chroma of 2 to 4. It typically is loam or sandy clay loam, but is clay loam in some pedons. It typically has 20 to 26 percent clay and ranges from 18 to 34 percent clay. It ranges from moderately acid to moderately alkaline. Some pedons have accumulations of carbonate and salts in the lower part of the Btn horizon.
The Bk horizon has hue of 10YR, 2.5Y, or 5Y; value of 5 to 7 and 4 to 6 moist; and chroma of 1 to 4. It typically is loam but some pedons are sandy clay loam, loam, fine sandy loam, or clay loam. It has few to many, fine to coarse accumulations of carbonate and fine accumulations of salts. It ranges from slightly to strongly alkaline.
The C horizon has hue of 10YR, 2.5Y, or 5Y; value of 5 to 7 and 4 to 6 moist; and chroma of 1 to 4. It is loam, fine sandy loam, clay loam, or sandy clay loam but is stratified with finer or coarser textured material in some pedons. Crystals of gypsum and other salts and accumulations of carbonate, if present, typically are in the upper part but are in all parts in some pedons. It ranges from slightly to very strongly alkaline.
COMPETING SERIES: These are the Bullock, Parchin, Rominell, Tismid and Tisworth series. Bullock and Parchin soils have bedrock at a depth of 20 to 40 inches. In addition, Bullock soils are less than 5 inches to the base of the E horizon. Rominell soils are more alkaline in the E and Bt horizons and have carbonates in the upper Bt horizon. Tismid soils do not have an E horizon and are strongly or very strongly alkaline in the Btn horizon. Tisworth soils have carbonates in the Bt horizon and are strongly and very strongly alkaline in the Btn horizon.
GEOGRAPHIC SETTING: Archin soils are on nearly level to moderately sloping upland fans and terraces. Slopes are plane to concave and range from 0 to 9 percent. The soils formed in stratified loamy and sandy alluvium. Mean annual temperature ranges from 39 to 45 degrees F, and mean annual precipitation ranges from 14 to 18 inches. Growing season is about 110 to 135 days; average growing season precipitation ranges from 10 to 13 inches; and growing degree days are about 2500 to 3100.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Bullock soils and the Assinniboine, Bullock, Chinook, Evanston, Kremlin, Loburn, and Yamac soils. Bullock soils are on slightly lower microrelief. Loburn soils are on similar landscapes and have fine textured natric horizons. Assinniboine, Chinook, Eapa, Kremlin, and Yamac soils are on higher smoother parts of the landscape. Assinniboine, Eapa, Chinook, Kremlin, and Yamac soils do not have a natric horizon.
DRAINAGE AND PERMEABILITY: Well drained. Runoff ranges from medium to very high depending on slope. Permeability is slow or very slow in the solum and moderate or moderately slow in the underlying material.
USE AND VEGETATION: These are used mainly for rangeland, but some areas are cultivated. Principal vegetation is western wheatgrass, needleandthread, blue grama, buffalograss, green needlegrass, and threadleaf sedges, and forbs.
DISTRIBUTION AND EXTENT: Northwestern South Dakota, eastern Montana, and possible in adjacent areas of North Dakota and Wyoming. Series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Butte County, South Dakota, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are: ochric epipedon - zone from the surface to a depth of 6 inches (A and E horizon); natric horizon - zone from 6 to 17 inches (Btn1 and Btn2 horizon).