LOCATION TWINROVA WY
Tentative Series
Rev. KCC-DJP-RJS
05/2017
TWINROVA SERIES
The Twinrova series consists of very deep, somewhat poorly drained soils that formed in alluvium. These soils are on stream terraces. Slopes are 0 to 2 percent. Mean annual precipitation is about 280 mm and annual air temperature is about 4.0 degrees C.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Oxyaquic Argixerolls
TYPICAL PEDON: Twinrova peaty loam, in pasture (colors are for dry soil unless otherwise noted).
A--0 to 6 cm; dark brown (10YR 3/3) peaty loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, very friable, slightly sticky, slightly plastic; many very fine and fine, and common medium, and few coarse roots; many irregular pores; slightly alkaline (pH 7.8); clear smooth boundary. (5 to 12 cm thick)
Bt1--6 to 25 cm; dark yellowish brown (10YR 4/4) clay loam, dark brown (10YR 3/3) moist; weak coarse subangular blocky structure; slightly hard, friable, moderately sticky, moderately plastic; common fine and medium roots; many irregular pores; 3 percent gravel; 10 percent faint clay films on all faces of peds and surfaces along root channels; slightly effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (10 to 25 cm thick)
Bt2--25 to 37 cm; brownish yellow (10YR 6/6) clay loam, yellowish brown (10YR 5/4) moist; weak coarse subangular blocky structure; slightly hard, friable, very sticky, very plastic; common very fine, fine and medium roots; many irregular pores; 3 percent gravel; 10 percent faint clay films on all faces of peds and surfaces along root channels; slightly effervescent; moderately alkaline (pH 8.2); clear smooth boundary.
Bt3--37 to 69 cm; brownish yellow (10YR 6/6) gravelly clay loam, yellowish brown (10YR 5/4) moist; weak coarse subangular blocky structure; slightly hard, friable, very sticky, very plastic; common fine and medium roots; many irregular pores; 20 percent gravel; 10 percent faint clay films on all faces of peds and surfaces along root channels; slightly effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (combined thickness of Bt2, Bt3 horizons -- 25 to 50 cm)
BC--69 to 150 cm; light yellowish brown (10YR 6/4) very gravelly sandy clay loam, brown (10YR 5/3) moist; 20 percent medium prominent red (2.5YR 4/6) moist, masses of oxidized iron on surfaces along pores; weak coarse subangular blocky structure; slightly hard, friable, very sticky, very plastic; few fine roots; common interstitial pores; 50 percent gravel; slightly effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Lincoln County, Wyoming; USGS Beckwith, Wyoming topographic quadrangle; 41 degrees 59 minutes 12.35 seconds north latitude and 110 degrees 56 minutes 46.69 seconds west longitude.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature -- 3.0 to 7.0 degrees C.
Mollic epipedon thickness -- 25 to 38 cm
Depth to argillic horizon -- 5 to 12 cm
Depth to a seasonally high water table and redoximorphic features -- 45 to 90 cm
A horizon
Hue: 10YR or 7.5YR dry or moist
Value: 2.5 or 3 dry; 2 or 2.5 moist
Chroma: 2 or 3 dry; 1 to 3 moist
Texture (less than 2 mm): peaty loam, loam
Clay content: 10 to 20 percent
Calcium carbonate equivalent: 0 to 3 percent
Reaction: pH 7.6 to 8.0
Bt1 horizon
Hue: 10YR or 7.5YR; dry or moist
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 3 or 4 dry; 2 or 3 moist
Clay content: 28 to 34 percent
Rock Fragments: 0 to 5 percent gravel
Calcium carbonate equivalent: 0 to 3 percent
Reaction: pH 7.8 to 8.4
Bt2, Bt3 horizons
Hue: 10YR or 7.5YR; dry or moist
Value: 3 to 7 dry; 3 to 6 moist
Chroma: 2 to 6 dry; 2 to 4 moist
Texture (less than 2 mm): clay loam, sandy clay loam
Clay content: 28 to 34 percent
Rock Fragments: 0 to 25 percent gravel
Calcium carbonate equivalent: 0 to 3 percent
Reaction: pH 7.8 to 8.4
BC horizon
Hue: 10YR or 7.5YR; dry or moist
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 3 or 4; dry or moist
Clay content: 25 to 34 percent
Rock Fragments: 35 to 55 percent gravel
Calcium carbonate equivalent: 0 to 3 percent
Reaction: pH 8.0 to 8.4
2C horizon (where present)
Hue: 10YR or 7.5YR; dry or moist
Value: 4 or 5; dry or moist
Chroma: 4 or 5 dry; 3 or 4 moist
Texture (less than 2 mm): sandy loam, loamy sand
Clay content: 5 to 14 percent
Rock Fragments: 10 to 45 percent gravel
Calcium carbonate equivalent: 0 to 3 percent
Reaction: pH 7.8 to 8.4
COMPETING SERIES:
FORGEN (WY) -- have Btn horizons
GEOGRAPHIC SETTING:
Landform: stream terraces
Elevation: 1,850 to 1,900 meters
Slope: 0 to 2 percent
Parent Material: alluvium
Climate: long, cold winters; cool, moist springs; short, cool summers.
Mean annual precipitation: 225 to 350 mm with peak periods of precipitation occurring during the winter
Mean annual air temperature: 3.0 to 6.0 degrees C.
Frost-free period: 40 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained; 1.5 to 5.0 um/sec.
USE AND VEGETATION: Twinrova soils are primarily used for irrigated hayland and irrigated pasture. The vegetation is mainly Garrison creeping meadow foxtail, timothy, tufted hairgrass, and other sedges, rushes, and forbs.
DISTRIBUTION AND EXTENT: Twinrova soils are of small extent in southwestern Wyoming. MLRA 13.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Lincoln County, Wyoming, 2017. The series name is derived from a local landmark.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon -- 0 to 25 cm (A, Bt1 horizons);
Argillic horizon -- 6 to 69 cm (Bt1, Bt2, Bt3 horizons);
Redoximorphic features -- 69 to 150 cm (BC horizon);
Particle-size control section -- from 6 to 56 cm (Bt1, Bt2, part of Bt3 horizons).
Twinrova soils have a frigid temperature regime and a xeric moisture regime and an oxyaquic moisture subclass.
Taxonomic version: Keys to Soil Taxonomy, Twelfth Edition, 2014.
National Cooperative Soil Survey
U.S.A.