LOCATION FERD MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Aridic Haplustalfs
TYPICAL PEDON: Ferd loam in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 3 inches; grayish brown (10YR 5/2) loam, dark grayish brown (10YR 4/2) moist; weak thin platy structure parting to moderate fine granular; soft, very friable, nonsticky and nonplastic; many very fine and fine roots; neutral (pH 7.2); abrupt smooth boundary. (2 to 4 inches thick)
E/Bt--3 to 8 inches; E part (60 percent) light brownish gray (10YR 6/2) loam, dark grayish brown (10YR 4/2) moist; B part (40 percent) brown (10YR 5/3) silty clay loam, dark brown (10YR 4/3) moist; moderate medium platy structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine tubular pores; few faint clay films on faces of peds; neutral (pH 7.2); abrupt smooth boundary. (3 to 6 inches thick)
Bt--8 to 13 inches; brown (10YR 5/3) silty clay loam, dark brown (10YR 4/3) moist; moderate fine and medium prismatic structure parting to moderate medium subangular blocky; very hard, friable, sticky and plastic; many very fine and fine roots; common very fine tubular pores; many faint clay films on faces of peds; neutral (pH 7.2); clear wavy boundary. (6 to 10 inches thick)
Bk1--13 to 20 inches; light brownish gray (10YR 6/2) silty clay loam, dark grayish brown (10YR 4/2) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; very hard, friable, sticky and plastic; common very fine and fine roots; many very fine tubular pores; few fine masses of lime; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (6 to 12 inches thick)
Bk2--20 to 32 inches; light brownish gray (2.5Y 6/2) silty clay loam, grayish brown (2.5Y 5/2) moist; weak fine and medium subangular blocky structure; hard, firm, sticky and plastic; few very fine roots; common very fine tubular pores; common fine masses of lime; violently effervescent; moderately alkaline (pH 8.4); gradual wavy boundary. (10 to 20 inches thick)
BCk--32 to 60 inches; light yellowish brown (2.5Y 6/4) silty clay loam, light olive brown (2.5Y 5/4) moist; massive; hard, firm, sticky and plastic; few very fine roots; common very fine and few fine tubular pores; few fine seams of lime; strongly effervescent; strongly alkaline (pH 8.6).
TYPE LOCATION: Chouteau County, Montana; 2,100 feet south and 1,200 feet east of the NW corner of sec. 21, T. 27 N., R. 5 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 43 to 47 degrees F.
Moisture control section - between 4 and 12 inches; dry in all parts between four-tenths and five-tenths of the cumulative days per year when the soil temperature at 20 inches is 41 degrees F or higher.
Control section - Bt horizon with 35 to 50 percent clay.
Depth to Bt horizon - 5 to 10 inches.
Depth to Bk horizon - 12 to 16 inches.
Some pedons have a Btk and Bky horizon. Some pedons have thin lenses of fine sandy loam or fine sand below 20 inches and a few gypsum crystals below 30 inches.
A horizon - Hue: 10YR or 2.5Y
Value: 3 or 4 moist
Clay content: 20 to 27 percent
Reaction: pH 6.6 to 7.8
E/Bt (or E, B/E) horizon - Hue: 10YR or 2.5Y
Texture: loam, clay loam, or silty clay loam
Clay content: 22 to 35 percent
Reaction: pH 6.6 to 7.8
Bt horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry
Chroma: 2 or 3
Texture: clay loam, silty clay loam, or clay
Clay content: 35 to 50 percent
EC: less than 2 mmhos/cm
Reaction: pH 6.6 to 8.4
Bk1 and Bk2 horizons - Hue: 10YR or 2.5Y
Value: 6 or 7 dry, 4 or 5 moist
Chroma: 2 or 3
Texture: clay loam or silty clay loam
Clay content: 27 to 40 percent
Calcium carbonate equivalent: 5 to 15 percent
SAR: 0 to 13
EC: 2 to 8 mmhos/cm
Reaction: pH 7.9 to 9.0
BCk horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2, 3, or 4
Texture: clay loam or silty clay loam
Clay content: 27 to 40 percent
Calcium carbonate equivalent: 5 to 15 percent
SAR: 8 to 13
EC: 4 to 8 mmhos/cm
Reaction: pH 7.9 to 9.6
Some pedons have a Bk3, By, or Bky horizon and thin lenses of fine sandy loam or fine sand below 20 inches.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - alluvial fans; drainageways; stream terraces; and till plains.
Elevation - 2,100 to 3,400 feet.
Slope- 0 to 8 percent.
Parent material - alluvium or glaciofluvial deposits.
Climate - long, cold winters; moist springs; hot, dry summers.
Mean annual precipitation - 10 to 14 inches.
Mean annual air temperature - 40 to 45 degrees F.
Frost-free period - 100 to 135 days.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Ferd soils are used mainly for nonirrigated crops and range. Potential native vegetation is mainly bluebunch wheatgrass, western wheatgrass, green needlegrass, and needleandthread.
DISTRIBUTION AND EXTENT: Ferd soils are of moderate extent in the plains area of north-central Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Toole County, Montana, 1991. Series proposed in Chouteau County Area, Montana, 1987.
REMARKS: Soils interpretation record: MT1079.
Diagnostic horizons and features recognized in this pedon are: ochric epipedon - from the surface to a depth of 6 inches (A and E/Bt horizons); argillic horizon - from 6 to 13 inches (Bt horizon); horizons of lime accumulation - from 13 to 60 inches (Bk1, Bk2, and BCk horizons); particle-size control section - from 6 to 13 inches (Bt horizon). Ferd soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.
Preferred classification is Aridic Glossic Eutroboralfs.