LOCATION WALTHAM MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Aridic Natrustalfs
TYPICAL PEDON: Waltham clay loam in rangeland (colors are for dry soil unless otherwise noted).
E--0 to 2 inches; light brownish gray (2.5Y 6/2) loam, dark grayish brown (2.5Y 4/2) moist; strong medium platy structure; hard, very friable, sticky and slightly plastic; common fine and very fine roots; few very fine tubular pores; neutral (pH 7.0); abrupt smooth boundary. (2 to 4 inches thick)
Bt1--2 to 6 inches; dark grayish brown (2.5Y 4/2) clay, very dark grayish brown (2.5Y 3/2) moist; strong medium columnar structure parting to strong medium subangular blocky; extremely hard, very firm, very sticky and very plastic; common fine and very fine roots; few very fine tubular pores; many distinct clay films on faces of peds; slightly alkaline (pH 7.4); clear smooth boundary. (4 to 8 inches thick)
Bt2--6 to 11 inches; dark grayish brown (2.5Y 4/2) clay, dark grayish brown (2.5Y 4/2) moist; strong medium prismatic structure parting to strong fine and medium subangular blocky; extremely hard, very firm, very sticky and very plastic; common fine and very fine roots; common very fine tubular pores; many distinct clay films on faces of peds; slightly alkaline (pH 7.6); clear wavy boundary. (5 to 10 inches thick)
Btkn--11 to 18 inches; pale brown (10YR 6/3) clay loam, brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate fine and medium subangular blocky; very hard, firm, very sticky and very plastic; common fine and very fine roots; common very fine tubular pores; few distinct clay films on faces of peds; few fine masses of lime; strongly effervescent; strongly alkaline (pH 8.6); clear wavy boundary. (6 to 20 inches)
Bkny1--18 to 30 inches; brown (10YR 5/3) clay loam, brown (10YR 4/3) moist; weak coarse prismatic structure parting to moderate fine and medium subangular blocky; hard, friable, sticky and plastic; few very fine roots; common very fine tubular pores; common fine masses of lime; common fine masses of gypsum and other salts; strongly effervescent; moderately alkaline (pH 8.4); gradual wavy boundary.
Bkny2--30 to 44 inches; light yellowish brown (2.5Y 6/4) clay loam, dark grayish brown (2.5Y 4/2) moist; weak fine and medium subangular blocky structure; hard, friable, sticky and plastic; common very fine tubular pores; few fine masses of lime; few fine masses of gypsum and other salts; strongly effervescent; moderately alkaline (pH 8.4); gradual wavy boundary. (Combined Bkny horizons 20 to 44 inches thick)
Bnyz--44 to 60 inches; light yellowish brown (2.5Y 6/4) clay loam, dark grayish brown (2.5Y 4/2) moist; weak fine and medium subangular blocky structure; hard, friable, sticky and plastic; common very fine tubular pores; few fine masses of gypsum and other salts; disseminated lime, strongly effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Chouteau County, Montana; 500 feet south and 1,000 feet east of the NW corner of sec. 28, T. 22 N., R. 9 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Depth to Btkn horizon - 10 to 16 inches.
Depth to Bkny horizon - 16 to 35 inches.
Depth to Bnyz horizon - 35 to more than 60 inches.
Bkn and Bknyz horizons are allowed. The surface may form a thin crust in cropland or rangeland.
E horizon - Hue: 2.5Y or 10YR
Value: 6 or 7 dry, 4 or 5 moist
Chroma: 2 or 3
Texture: loam or clay loam (clay loam or clay when mixed to 7 inches)
Clay content: 20 to 35 percent (35 to 45 percent when mixed to 7 inches)
Rock fragments: 0 to 5 percent pebbles
EC: 0 to 2 mmhos/cm
SAR: 0 to 13
Reaction: pH 6.6 to 8.4
A 1- or 2-inch A horizon with granular structure above the E horizon is allowed.
Bt horizons - Hue: 2.5Y or 10YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 2 or 3
Texture: clay loam or clay
Clay content: 35 to 60 percent
Rock fragments: 0 to 5 percent pebbles
EC: 0 to 2 mmhos/cm
SAR: 4 to 13
Reaction: pH 7.4 to 8.4
Btkn horizon - Hue: 2.5Y or 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2, 3, or 4
Texture: clay loam or clay
Clay content: 30 to 45 percent
Rock fragments: 0 to 5 percent mainly pebbles
EC: 0 to 4 mmhos/cm
SAR: 13 to 25
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.9 to 9.0
Bkny horizons - Hue: 2.5Y or 10YR
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Texture: clay loam
Clay content: 27 to 40 percent
Rock fragments: 0 to 5 percent pebbles
EC: 4 to 16 mmhos/cm
SAR: 4 to 20
Gypsum: 3 to 5 percent
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 9.0
Bnyz horizon - Hue: 2.5Y or 10YR
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Texture: clay loam
Clay content: 27 to 40 percent
Rock fragments: 0 to 5 percent pebbles
EC: 4 to 16 mmhos/cm
SAR: 4 to 20
Gypsum: 3 to 5 percent
Calcium carbonate equivalent: 5 to 12 percent
Reaction: pH 7.4 to 9.0
COMPETING SERIES:
Absher (MT) - has electrical conductivity of 8 to 16 mmhos/cm and sodium absorption ratio of 18 to 70 in the Bt horizons.
Creed (MT) - has A and E horizons with a combined thickness of 4 to 10 inches; has Btn horizons.
Elloam (MT) - has Btn horizons with electrical conductivity of 2 to 8 mmhos/cm.
Gerdrum (MT) - has Btn horizons; formed in alluvium or glacialfluvial deposits.
Oburn (MT) - is skeletal above 40 inches.
Thoeny (MT) - has Btn horizons.
Weingart (MT) - has a paralithic contact of semiconsolidated shale at 20 to 40 inches.
GEOGRAPHIC SETTING:
Landform - till plains.
Elevation - 3,000 to 4,000 feet.
Slope- 0 to 8 percent.
Parent material - till.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 13 to 19 inches.
Mean annual air temperature - 40 to 45 degrees.
Frost-free period - 90 to 125 days.
DRAINAGE AND PERMEABILITY: Well drained; very slow permeability.
USE AND VEGETATION: Waltham soils are used for both rangeland and nonirrigated cropland. The potential native vegetation is western wheat grass, green needlegrass, Nuttall saltbush, and winterfat.
DISTRIBUTION AND EXTENT: Waltham soils are in north-central Montana on the till plains. They are moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Chouteau County, Montana 1991.
REMARKS: Soil interpretations record: MT1264. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the surface to 2 inches (E horizon); an argillic horizon from 2 to 11 inches, which is also the particle-size control section (Bt1, Bt2 horizons); accumulation of lime from 11 to 44 inches (Btkn, Bkny1, Bkny2 horizons); accumulation of gypsum from 18 to 60 inches (Bkny1, Bkny2, Bnyz horizons).
ADDITIONAL INFORMATION: Lincoln laboratory data S90MT-015-791.