LOCATION FORKWOOD WY+MTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Ustic Haplargids
TYPICAL PEDON: Forkwood loam - utilized as rangeland. (Colors are for dry soil unless otherwise stated)
A--0 to 5 inches; brown (10YR 5/3) loam, dark grayish brown (10YR 4/2) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; many fine and medium roots throughout; neutral; abrupt smooth boundary. (1 to 6 inches thick)
Bt--5 to 12 inches; brown (10YR 5/3) clay loam, brown (10YR 4/3) moist; strong medium angular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common fine and medium roots throughout; common distinct clay films on faces of peds; slightly alkaline; clear smooth boundary. (6 to 20 inches thick)
Btk--12 to 20 inches; light brownish gray (2.5Y 6/2) clay loam, dark grayish brown (2.5Y 4/2) moist; strong medium angular blocky structure; hard, firm, moderately sticky and moderately plastic; few fine and medium roots throughout; few faint clay films on faces of peds; few masses of carbonates; slightly effervescent; slightly alkaline; clear smooth boundary. (3 to 10 inches thick)
Bk--20 to 30 inches; light brownish gray (2.5Y 6/2) loam, light olive brown (2.5Y 5/4) moist; moderate medium subangular blocky structure parting to weak fine subangular blocky; slightly hard, friable, slightly sticky and sligtly plastic; few fine roots throughout; few fine threads and masses of carbonates throughout; strongly effervescent; moderately alkaline; gradual wavy boundary. (9 to 45 inches thick)
BCk--30 to 60 inches; light brownish gray (2.5Y 6/2) loam, grayish brown (2.5Y 5/2) moist; massive; soft, very friable, slightly sticky and slightly plastic; few fine roots throughout; few masses of carbonates throughout; strongly effervescent; moderately alkaline. (0 to 40 inches thick)
TYPE LOCATION: Niobrara County, Wyoming; about 1,000 feet south and 1,100 feet west of the northeast corner of sec. 2, T. 36 N., R. 65 W.
RANGE IN CHARACTERISTICS: Depth to the base of the argillic horizon is 10 to 33 inches, and depth to continuous horizons of carbonate accumulation is 10 to 33 inches. Rock fragments 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 21-27, and 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 ranges from 47 to 53 degrees F., and the soil temperature at a depth of 20 inches is 41 degrees F. or more for 175 to 192 days. EC ranges from 0 to 4 mmhos/cm throughout the profile. Bedrock is deeper than 60 inches.
The A horizon has hue of 2.5Y or 10YR, value of 4 to 6 dry and 3 to 5 moist, and chroma of 2 to 4. A vesicular crust occurs on some pedons. Texture is very fine sandy loam, loam, clay loam or fine sandy loam. Reaction is neutral through moderately alkaline.
The Bt horizon has hue of 2.5Y, 10YR or 7.5YR, value of 4 to 7 dry and 3 to 5 moist, and chroma of 2 to 4. Texture is loam or clay loam with 18 to 35 percent clay and more than 15 but less than 35 percent fine sand or coarser. Reaction is neutral through moderately alkaline.
The Btk horizon has hue of 2.5Y or 10YR, value of 4 to 7 dry and 3 to 5 moist, and chroma of 2 to 4. Texture is loam or clay loam. It is slightly alkaline or moderately alkaline. It has 3 to 12 percent calcium carbonate equivalent.
The Bk horizon has hue of 5Y, 2.5Y or 10YR, value of 5 to 7 dry and 4 to 6 moist, and chroma of 2 to 4. Texture is loam, fine sandy loam, very fine sandy loam or clay loam. This horizon has 1 to 14 percent authigenic calcium carbonate accumulation. It is moderately alkaline or strongly alkaline.
The C horizon, when present, has hue of 5Y to 10YR, value of 5 to 7 dry, 4 to 6 moist, and chroma of 2 to 4. Carbonates range from 1 to 8 percent and are mostly allogenic. ESP ranges from 4 to 12. Reaction is moderately or strongly alkaline.
COMPETING SERIES: These are the Balon, Blancot, Bowbac, Buckle, Cambria, Cerrillos, Cushman, Decolney, Doakum, Gaddes, Gapmesa, Hagerman, Hagerwest, Hiland, Los Alamos, Mentmore, Oelop, Olney, Palacid, Penistaja, Pokeman, Potts, Pugsley, Quagwa, Redpen, Spangler, Spenlo, Sundance, Teckla and Yenlo series (Gaddes and Yenlo are presumed to be competing pending an update of the classification). Balon soils are noncalcareous. Blancot soils have discontinuous horizons of carbonate accumulation. Bowbac, Cerrillos, Cushman, Gaddes, Gapmesa, Hagerman, Pokeman, Pugsley, Spangler and Threetop soils have bedrock at a depth of 20 to 40 inches. Buckle and Palacid soils have sola more than 40 inches thick. Cambria soils have Bt horizons that have a base at less than 10 inches from the soil surface. Cerrillos, Potts and Spenlo soils have hue of 7.5YR or redder throughout the profile. Decolney, Hiland, Olney and Penistaja soils have more than 35 percent fine sand and coarser in the particle-size control section. Doakum soils have average annual soil temperature of 52 to 56 degrees F. Hagerwest, Mentmore and Quagwa soils are driest during May and June. Los Alamos soils have pumice and ash at depths of 20 to 50 inches. Oelop, Palacid and Yenlo soils are moist in some or all parts of the moisture control section for 60 consecutive days following July 15 and are moist in some parts for at least 90 cumulative days when the soil temperature at a depth of 20 inches is 41 degrees F. Redpen soils have hue of 2.5YR. Sundance and Teckla soils have lithologic discontinuities.
GEOGRAPHIC SETTING: Forkwood soils are on terraces, alluvial fans, fan remnants, hills, ridges and pediments. Slopes are 0 to 15 percent. The soils formed in slopewash alluvium derived from interbedded shales and argillaceous sandstone. Elevations are 3,500 to 6,000 feet. The average annual precipitation is 10 to 14 inches with over half of the annual precipitation falling in April, May, and June and less than one inch falling in each month of July, August, September, and October. The mean annual air temperature ranges from 43 to 51 degrees F. The estimated frost-free season is about 105 to 130 days depending upon elevation, aspect, and air drainage.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Cushman and Hiland soils and the Absted, Arvada, Haverdad, Kishona and Shingle soils. Cushman and Shingle soils are on shoulder slopes and summits of hills and ridges. Shingle soils have bedrock at a depth of 4 to 20 inches. Absted, Arvada, Hiland and Kishona soils occur on similar landscape positions as the Forkwood soils. Absted and Arvada soils have natric horizons. Haverdad and Kishona soils lack an argillic horizon. Haverdad soils occur on flood plains and terraces.
DRAINAGE AND PERMEABILITY: Well drained; low to medium runoff; moderate permeability.
USE AND VEGETATION: These soils are used principally for livestock grazing and wildlife habitat. Native vegetation is big sagebrush, bluebunch wheatgrass, Sandberg bluegrass, and needleandthread.
DISTRIBUTION AND EXTENT: Central and northern basin areas of Wyoming and northern Colorado.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Washakie County, Wyoming; 1980.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 5 inches (A horizon)
Argillic horizon - 5 to 20 inches (Bt and Btk horizons)
SIR- WY1139
LRR- G