LOCATION FORGEN WY
Tentative Series
Rev. KCC-DJP-RJS
05/2017
FORGEN SERIES
The Forgen 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: Forgen peaty silt loam, in pasture (colors are for dry soil unless otherwise noted).
A--0 to 6 cm; dark brown (10YR 3/3) peaty silt loam, very dark brown (10YR 2/2) moist; weak medium granular structure; soft, very friable, moderately sticky, moderately plastic; many very fine and fine, and common medium roots; many irregular pores; very slightly effervescent; very strongly alkaline (pH 9.4); abrupt smooth boundary. (4 to 8 cm thick)
Btn1--6 to 28 cm; brown (10YR 4/3) clay loam, very dark grayish brown (10YR 3/2) moist; weak coarse subangular blocky structure; moderately hard, firm, very sticky, very plastic; many very fine and fine, and common medium roots; many irregular pores; 10 percent faint clay films on all faces of peds and surfaces along root channels; very slightly effervescent; very strongly alkaline (pH 9.2); clear smooth boundary.
Btn2--28 to 61 cm; light yellowish brown (10YR 6/4) clay loam, brown (10YR 5/3) moist; 10 percent, medium, faint, irregular, very dark grayish brown (10YR 3/2) moist, redoximorphic feature; weak coarse subangular blocky structure; moderately hard, firm, very sticky, very plastic; few fine roots; many irregular pores; 10 percent faint clay films on all faces of peds; very slightly effervescent; strongly alkaline (pH 9.0); clear smooth boundary. (combined thickness of Btn1, Btn2 -- 30 to 65 cm)
C1--61 to 99 cm; light yellowish brown (10YR 6/4) sandy clay loam, brown (10YR 5/3) moist; 10 percent, fine, prominent, irregular, 7.5YR (4/6) moist, masses of oxidized iron in matrix; massive; moderately hard, firm, moderately sticky, moderately plastic; few fine roots; common interstitial pores; very slightly effervescent; moderately alkaline (pH 8.2); clear smooth boundary.
C2--99 to 119 cm; yellowish brown (10YR 5/4) sandy clay loam, brown (10YR 4/3) moist; 10 percent fine distinct irregular 7.5YR (4/6), moist, masses of oxidized iron in matrix; massive; moderately hard, firm, very sticky, very plastic; few fine roots; common interstitial pores; very slightly effervescent; moderately alkaline (pH 8.2); clear smooth boundary.
C3--119 to 150 cm; yellowish brown (10YR 5/4) sandy clay loam, brown (10YR 4/3) moist; 30 percent, coarse, prominent, irregular, 7.5YR (4/6) moist, masses of oxidized iron in matrix; massive; moderately hard, firm, very sticky, very plastic; few fine roots; few interstitial pores; very slightly effervescent; moderately alkaline (pH 8.2). (combined thickness of C1, C2, C3 -- greater than 80 cm)
TYPE LOCATION: Lincoln County, Wyoming; USGS Beckwith, Wyoming topographic quadrangle; 41 degrees 57 minutes 21.80 seconds north latitude and 110 degrees 57 minutes 21.14 seconds west longitude.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature -- 3.0 to 7.0 degrees C.
Mollic epipedon thickness -- 18 to 36 cm
Depth to argillic horizon -- 4 to 8 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 to 3 dry or moist
Chroma: 2 or 3 moist
Texture (less than 2 mm): silt loam, loam
Clay content: 15 to 25 percent
Calcium carbonate equivalent: 0 to 3 percent
Sodium adsorption ratio: 8 to 15
Reaction: pH 8.8 to 9.4
Btn1, Btn2 horizons
Hue: 10YR or 7.5YR dry or moist
Value: 2.5 to 6 dry; 2.5 to 5 moist
Chroma: 3 or 4 dry; 2 or 3 moist
Clay content: 28 to 34 percent
Calcium carbonate equivalent: 0 to 3 percent
Sodium adsorption ratio: 8 to 15
Reaction: pH 8.8 to 9.2
C horizons
Hue: 10YR or 7.5YR dry or moist
Value: 5 to 8 dry; 4 to 6 moist
Chroma: 3 to 5 dry; 3 or 4 moist
Texture (less than 2 mm): clay loam, sandy clay loam
Clay content: 21 to 34 percent
Calcium carbonate equivalent: 0 to 3 percent
Sodium adsorption ratio: 0 to 3
Reaction: pH 8.0 to 8.4
COMPETING SERIES:
TWINROVA (WY) - have sodium absorption ratio less than 3 throughout the soil profile
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; 0.5 - 15.0 um/sec.
USE AND VEGETATION: Forgen 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: Forgen 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 28 cm (A, Bt1 horizons);
Argillic horizon -- 6 to 61 cm (Btn1, Btn2 horizons);
Particle-size control section -- from 6 to 56 cm (Btn1, part of Btn2 horizons).
Forgen 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.