LOCATION TISWORTH WY+CO UTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Ustic Natrargids
TYPICAL PEDON: Tisworth sandy loam-rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 3 inches; pale brown (10YR 6/3) sandy loam, brown (10YR 4/3) moist; weak medium platy structure; soft, very friable, slightly sticky and slightly plastic; many fine roots; strongly effervescent, lime disseminated; strongly alkaline (pH 9.2); abrupt wavy boundary. (2 to 4 inches thick)
Btn--3 to 8 inches; brown (7.5YR 5/4) sandy clay loam, dark brown (7.5YR 4/4) moist; moderate medium columnar structure parting to moderate very fine angular blocky; hard, friable, sticky and plastic; many fine, few medium roots; continuous moderately thick clay films on all faces of peds; strongly effervescent, lime disseminated; very strongly alkaline (pH 9.4); clear wavy boundary. (4 to 16 inches thick)
Bnk--8 to 16 inches; light brown (7.5YR 6/4) loam, brown (7.5YR 5/4) moist; moderate coarse subangular blocky structure; slightly hard, very friable, sticky and plastic; few fine and medium roots; violently effervescent, lime disseminated and as common soft masses and threads; very strongly alkaline (pH 9.4); gradual wavy boundary. (3 to 10 inches thick)
C1--16 to 24 inches; light brown (7.5YR 6/4) loam, brown (7.5YR 4/4) moist; massive; slightly hard, very friable, sticky and plastic; few fine and medium roots; strongly effervescent, lime disseminated and as few fine threads; very strongly alkaline (pH 9.2); clear wavy boundary. (6 to 12 inches thick)
C2--24 to 60 inches; pale brown (10YR 6/3) gravelly loam, brown (10YR 4/3) moist; massive; soft, very friable, sticky and slightly plastic; strongly effervescent, lime disseminated; 20 percent pebbles; strongly alkaline (pH 8.6).
TYPE LOCATION: Sweetwater County, Wyoming; 600 feet southwest of old sheep corral in NW1/4, NW1/4 of sec. 25, T. 12 N., R. 105 W.
RANGE IN CHARACTERISTICS: Depth to the base of the Btn (natric) horizon ranges from 7 to 20 inches. The particle-size control section is either the entire natric horizon or when the base of the Btn is less than 10 inches, it is from the top of the natric to 40 inches. Clay ranges from 18 to 35 percent and the control section contains from 15 to 40 percent exchangeable sodium. These soils are typically strongly effervescent to the surface but may be leached as much as 15 inches when an E horizon is present. The mean annual soil temperature is 43 to 47 degrees F, and the mean summer soil temperature is 59 to 63 degrees F. EC is quite variable and ranges from 4 to 16 mmhos throughout the profile.
The A or E horizon has hue of 10YR through 5YR, value of 5 through 7 dry, 3 through 5 moist, and chroma of 2 through 4. Coarse fragments range from 0 to 15 percent angular pebbles. Reaction ranges from mildly through very strongly alkaline. An E horizon may be present in some pedons.
The Btn horizon has hue of 2.5Y through 5YR, value of 4 through 7 dry, 3 through 5 moist, and chroma of 2 through 6. Texture is clay loam, sandy clay loam, or loam with 18 to 35 percent clay. Coarse fragments range from 0 to 15 percent angular pebbles. Exchangeable sodium ranges from 15 to 40 percent. Reaction ranges from strongly through very strongly alkaline.
The Bnk or Bk horizon has hue of 10YR through 5YR, value of 6 or 7 dry, 4 through 6 moist, and chroma of 2 through 6. Texture is sandy loam,loam, sandy clay loam, or clay loam. Thin strata of varying textures are common in some pedons. Coarse fragments range from 0 to 20 percent angular pebbles when averaged. Reaction ranges from strongly through very strongly alkaline. ESP ranges from 12 to 35. A Btnk horizon is present in some pedons.
The C or Bk horizon has hue of 10YR through 5YR, value of 5 through 7 dry, 4 through 6 moist, and chroma of 2 through 4. Texture is variable with thin strata common in some pedons but is loam, sandy loam, clay loam, or sandy clay loam when averaged. ESP ranges from 12 to 35 percent when averaged. Reaction is moderately through very strongly alkaline. Buffering by gypsum may occur in some pedons.
COMPETING SERIES: These are the Archin, Bullock, Parchin, Rominell and Tismid series. Archin soils have medium acid through mildly alkaline Bt horizons and are noncalcareous through the Bt. Bullock and Parchin soils have bedrock at 20 to 40 inches. Rominell soils do not have a Bk horizon but have pedogenic accumulations of gypsum and salts more soluble than gypsum. Tismid soils have a Bkz horizon.
GEOGRAPHIC SETTING: Tisworth soils are on alluvial fans, fan aprons, and terraces. These soils formed in alluvium weathered from sodic shale and interbedded sandstone. Elevations range from 6,000 to 7,500 feet. The mean annual precipitation is about 12 inches and ranges from 10 to 14 inches; about half falls as snow or rain in April, May, and early June. The mean annual temperature ranges from 39 to 45 degrees F. The frost-free period is estimated to range from 60 to 110 days depending upon elevation, aspect, and air drainage.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Absher, Almy, Forelle, Goslin, Poposhia, and Ryan Park soils. Absher soils have more than 35 percent clay in the control section. Almy and Forelle soils have less than 15 percent exchangeable sodium in the Bt horizon. Gaslin and Poposhia soils are weakly developed, and, in addition, Gaslin soils have less than 18 percent clay in the control section. Ryan Park soils are coarse-loamy and have less than 15 percent exchangeable sodium in the Bt horizon.
DRAINAGE AND PERMEABILITY: Well drained; medium or rapid runoff depending upon slope and surface crusting; slow permeability.
USE AND VEGETATION: Rangeland and wildlife habitat. Native vegetation is greasewood, Gardner saltbush, bottlebrush squirreltail, Indian ricegrass, and thickspike wheatgrass.
DISTRIBUTION AND EXTENT: Southwestern and western Wyoming and northwestern Colorado. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Rio Blanco County, Colorado; 1979.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon--0 to 3 inches (A)
Natric horizon--3 to 16 inches (Btn,Bnk)
Borollic feature--Organic carbon and temperature regime meet the requirements for Borollic.