LOCATION PLATSHER WY+MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aridic Paleustolls
TYPICAL PEDON: Platsher loam-rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 7 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, friable, sticky and slightly plastic; neutral (pH 7.1); abrupt smooth boundary. (4 to 9 inches)
Bt1--7 to 11 inches; grayish brown (10YR 5/2) clay, very dark grayish brown (10YR 3/2) moist; strong medium prismatic structure parting to strong fine angular blocky; extremely hard, firm, sticky and plastic; many prominent clay films on vertical and horizontal faces of peds; mildly alkaline (pH 7.6); gradual smooth boundary.
Bt2--11 to 21 inches; grayish brown (10YR 5/2) clay, dark grayish brown (10YR 4/2) moist; strong medium prismatic structure parting to strong medium and fine angular blocks; extremely hard, very firm, sticky and plastic; many prominent clay films on vertical and horizontal faces of peds; about 3 percent gravel; mildly alkaline (pH 7.6); gradual smooth boundary. (Combined thickness of Bt horizons is 10 to 25 inches.)
Bk--21 to 28 inches; light brownish gray (2.5Y 6/2) clay loam, dark grayish brown (2.5Y 4/2) moist; moderate coarse prismatic structure parting to moderate coarse and medium angular and subangular blocky; extremely hard, firm, sticky and plastic; strongly effervescent, calcium carbonate as many distinct fine seams and coarse soft masses; about 3 percent gravel; moderately alkaline (pH 8.2); gradual smooth boundary. (4 to 10 inches thick)
2Bk1--28 to 40 inches; light gray (2.5Y 7/2) gravelly clay loam, light brownish gray (2.5Y 6/2) moist; weak coarse subangular blocky structure; hard, firm, sticky and slightly plastic; strongly effervescent, calcium carbonate as many distinct fine and medium seams; 20 percent gravel; moderately alkaline (pH 8.2); gradual smooth boundary. (10 to 20 inches thick)
2Bk2--40 to 60 inches; grayish brown (2.5Y 5/2) gravelly clay loam, dark grayish brown (2.5Y 4/2) moist; massive; hard, friable, sticky and slightly plastic; strongly effervescent, calcium carbonate as common distinct thin seams; 25 percent gravel; moderately alkaline (pH 8.2).
TYPE LOCATION: Sheridan County, Wyoming; NE1/4, NE1/4, sec. 8, T. 55., R. 84 W.
RANGE IN CHARACTERISTICS: The mollic epipedon is 7 to 19 inches thick. Depth to continuous horizons of carbonate accumulation ranges from 15 to 30 inches. The mean annual soil temperature ranges from 47 to 53 degrees F. The soils are dry in all parts of the moisture control section for at least 60 consecutive days following mid-July in most years. Coarse fragments range from 0 to 15 percent in the A and Bt horizons and from 15 to 35 percent in the 2Bk horizons.
The A horizon has hue of 10YR or 2.5Y, value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3. Reaction is neutral or mildly alkaline. An E horizon may be present in some pedons.
The Bt horizon has hue of 10YR or 2.5Y, value of 4 through 6 dry, 2 through 4 moist, and chroma of 2 through 4. The upper part of this horizon is typically part of the mollic epipedon. Texture is typically clay and less typically clay loam with 35 to 55 percent clay and more than 15 but less than 35 percent fine or coarser sand. Reaction is mildly alkaline or moderately alkaline. The Bt horizon is typically free of carbonates, but some pedons may be slightly effervescent in the lower part.
The Bk horizon has hue of 10YR or 2.5Y, value of 6 or 7 dry, 4 through 6 moist, and chroma of 2 through 4. Texture is clay loam with 27 to 40 percent clay. Reaction is moderately alkaline or strongly alkaline. Calcium carbonate ranges from 10 to 30 percent.
The 2Bk horizon has hue of 10YR or 2.5Y, value of 5 through 8 dry, 4 through 7 moist, and chroma of 2 through 4. Texture is gravelly clay loam or gravelly loam with 20 to 32 percent clay. Calcium carbonate ranges from 15 to 35 percent and decrease with depth. Reaction is moderately alkaline or strongly alkaline.
COMPETING SERIES: These are the Fondis, Iliff, Jonpal, Platmak, Platner, and Weld series. Fondis, Platner, and Weld soils do not have a calcic horizon. Also, Fondis and Weld soils have less than 15 percent fine or coarser sand in the argillic horizon. Jonpal soils have a paralithic contact at 20 to 40 inches. Iliff soils have a lithic contact at 20 to 40 inches. Platmak soils have less than 15 percent coarse fragments throughout the solum.
GEOGRAPHIC SETTING: Platsher soils are on relict terraces. Slopes range from 0 to 9 percent. Elevation ranges from 3,800 to 4,500 feet. The mean annual precipitation is about 16 inches and ranges from 15 to 19 inches. The mean annual temperature ranges from 45 to 51 degrees F. The frost-free period ranges from 100 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bidman, Big Horn, Nihill, Wolf, and Wolfvar soils. The Bidman and Big Horn soils have an ochric epipedon. Nihill soils have no argillic horizon and are loamy-skeletal. Wolf soils are fine-loamy. Wolfvar soils have an abrupt textural boundary.
DRAINAGE AND PERMEABILITY: Well drained; slow or medium runoff; slow permeability.
USE AND VEGETATION: Irrigated and dryland crops, rangeland, and wildlife habitat. Native vegetation consists of prairie junegrass, western wheatgrass, needleandthread grass, Idaho fescue, and big sagebrush.
DISTRIBUTION AND EXTENT: Northeastern Wyoming. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Sheridan County, Wyoming; 1987.
REMARKS: Diagnostic horizons and features recognized in this pedon are: 1. Mollic epipedon - 0 to 11 inches (A,Bt1)
2. Argillic horizon - 7 to 21 inches (Bt1,Bt2)
3. Lithologic discontinuity - 28 inches
4. Calcic horizon - 28 to 40 inches (2Bk1)
5. An absolute increase in clay of greater than 20 percent
at the upper boundary of the Bt1 horizon within a
vertical distance of 7.5 cm.
6. Aridic subgroup - usually dry in some or all parts of the
moisture control section when the soil temperature is 41
degrees F. or warmer at a depth of 20 inches.
7. SIR - WY0701