LOCATION VERSON MTEstablished Series
TAXONOMIC CLASS: Clayey over loamy-skeletal, smectitic over mixed, superactive, frigid Aridic Argiustolls
TYPICAL PEDON: Verson clay loam, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 4 inches; grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate very fine granular structure; soft, very friable, sticky and plastic; many fine and very fine and few medium roots; 5 percent pebbles; neutral (pH 7.2); clear wavy boundary. (4 to 8 inches thick)
Bt1--4 to 7 inches; grayish brown (10YR 5/2) clay, very dark grayish brown (10YR 3/2) moist; moderate medium prismatic structure parting to strong fine and very fine subangular blocky; hard, friable, sticky and very plastic; many fine and very fine and few medium roots; many fine and very fine pores; many distinct clay films on faces of peds; 5 percent pebbles; neutral (pH 7.2); clear wavy boundary.
Bt2--7 to 12 inches; brown (10YR 5/3) silty clay loam, dark brown (10YR 4/3) moist; strong medium prismatic structure parting to strong fine and very fine subangular blocky; very hard, friable, sticky and very plastic; many fine and very fine and few medium roots; many fine and very fine pores; many distinct clay films on faces of peds; slightly alkaline (pH 7.4); abrupt irregular boundary. (Combined thickness of the Bt horizons is 7 to 17 inches)
Bk1--12 to 18 inches; light brownish gray (10YR 6/2) with grayish brown (10YR 5/2) coatings on peds, silty clay loam, dark grayish brown (2.5Y 4/2) moist; moderate medium prismatic structure parting to moderate fine and medium subangular blocky; very hard, friable, sticky and plastic; many fine and very fine and few medium roots; many fine and very fine pores; less than 5 percent pebbles; many fine and few coarse irregular masses of lime, strongly effervescent; moderately alkaline (pH 8.4); gradual wavy boundary.
Bk2--18 to 29 inches; light gray (2.5Y 7/2) silty clay loam, light yellowish brown (2.5Y 6/4) moist; weak very coarse prismatic structure parting to weak fine and medium subangular blocky; slightly hard, friable, sticky and plastic; common fine and very fine and few medium roots; many fine and very fine pores; 5 percent pebbles; disseminated lime; many medium irregular masses of lime; violently effervescent; moderately alkaline (pH 8.4); clear wavy boundary. (Combined Bk horizons 0 to 28 inches thick)
2Bk3--29 to 60 inches; very pale brown (10YR 7/3) extremely gravelly loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few fine and very fine roots to 40 inches; common fine and very fine pores; 60 percent pebbles and 5 percent cobbles; pebbles completely coated with lime to 40 inches; violently effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Fergus County, Montana; 2,500 feet east and 1,200 feet south of the NW corner of sec. 24, T. 15 N., R. 24 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 43 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 7 to 12 inches.
Depth to Bk horizon - 11 to 20 inches.
Depth to 2Bk3 horizon - 15 to 36 inches.
Btk and 2C horizons are allowed.
A horizon - Hue: 10YR or 2.5Y
Value: 3 or 4 moist
Chroma: 2 or 3
Texture: loam or clay loam
Clay content: 18 to 40 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent pebbles
Reaction: pH 6.1 to 7.3
Bt horizons - Hue: 10YR or 2.5Y
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 2, 3, or 4
Texture: clay loam, silty clay loam, clay, or silty clay
Clay content: 35 to 55 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles; 0 to 15 percent pebbles
Reaction: pH 6.1 to 7.8
Bk horizon - Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 2, 3, 4, or 6
Texture: clay loam, silty clay loam, clay, or silty clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 25 percent--0 to 5 percent cobbles, 0 to 20 percent pebbles
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
2Bk3 horizon - Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 2, 3, 4, or 6
Texture: sandy loam or loam
Clay content: 5 to 25 percent
Rock fragments: 50 to 85 percent--5 to 10 percent cobbles, 40 to 75 percent pebbles
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
COMPETING SERIES: This is the Nilrap series. The Nilrap series has hue of 7.5YR or redder below the A horizon. In addition, it has carbonates at depths of more than 20 inches.
GEOGRAPHIC SETTING:
Landform - stream terraces; alluvial fans.
Elevation - 2,200 to 5,200 feet.
Slope- 0 to 8 percent.
Parent material - calcareous clayey alluvium over very gravelly or extremely gravelly alluvium.
Climate - long; cold winters; moist springs; warm summers.
Mean annual air temperature - 41 to 45 degrees F.
Mean annual precipitation - 10 to 14 inches.
Frost-free period - 95 to 135 days.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability through the Bk2 horizon and moderately rapid in the 2Bk3 horizon.
USE AND VEGETATION: Verson soils are used mainly for rangeland and dryland crops. Potential native vegetation is mainly bluebunch wheatgrass, western wheatgrass, green needlegrass, and thickspike wheatgrass.
DISTRIBUTION AND EXTENT: Verson soils are of moderate extent in central and eastern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Fergus County, Montana, 1979.
REMARKS: Soil interpretation record: MT0337.
Diagnostic horizons and features recognized in this pedon are: mollic epipedon - from the soil surface to 7 inches (A and Bt1 horizons); argillic horizon - from 4 to 12 inches (Bt1 and Bt2 horizons); contrasting particle-size control section - from 4 to 40 inches. Verson soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.