LOCATION PACHEL MTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Pachic Argiustolls
TYPICAL PEDON: Pachel loam, cropland (colors are for dry soil unless otherwise noted).
Ap--0 to 6 inches; dark gray (10YR 4/1) loam, very dark gray (10YR 3/1) moist; moderate fine and medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; 5 percent pebbles; slightly acid (pH 6.2); abrupt smooth boundary. (4 to 7 inches thick)
Bt1--6 to 13 inches; dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, firm, sticky and plastic; few very fine tubular pores; few very fine roots; common faint clay films on faces of peds and in pores; 5 percent pebbles; neutral (pH 6.8); gradual wavy boundary.
Bt2--13 to 22 inches; grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate coarse and medium prismatic structure; hard, firm, very sticky and very plastic; few very fine tubular pores; few very fine roots; many faint clay films on faces of peds and in pores; 10 percent pebbles; slightly alkaline (pH 7.4); clear smooth boundary. (The combined thickness of the Bt horizons is 12 to 34 inches)
Bk--22 to 60 inches; pale brown (10YR 6/3) very gravelly sandy clay loam, brown (10YR 4/3) moist; weak fine granular structure; hard, firm, slightly sticky and slightly plastic; few very fine roots; 40 percent pebbles and 10 percent cobbles; disseminated lime; common faint lime coating on some of the pebbles and cobbles; strongly effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Fallon County, Montana; 2,000 feet east and 2,300 feet south of the NW corner sec. 4, T.9 N., R.60 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 16 to 34 inches, may include part or all of the Bt horizon.
Depth to Bk horizon - 16 to 34 inches, but mainly 20 to 28 inches.
The A horizon when mixed to seven inches does not have a chroma of 1 or less.
Ap horizon - Value: 4 or 5 dry; 2 or 3 moist
Chroma: 1, 2, or 3
Clay content: 18 to 25 percent
Rock fragments: 0 to 15 percent pebbles
Reaction: pH 6.1 to 7.3
Bt1 horizon - Value: 4 or 5 dry; 2 or 3 moist
Chroma: 1, 2, or 3
Texture: loam or clay loam
Clay content: 18 to 35 percent
Rock fragments: 0 to 15 percent pebbles
Reaction: pH 6.6 to 7.8
Bt2 horizon - Value: 4 or 5 dry; 2 or 3 moist
Chroma: 1, 2, or 3
Clay content: 27 to 35 percent
Rock fragments: 0 to 15 percent pebbles
Effervescence: none to slight
Reaction: pH 6.6 to 7.8
Bk horizon - Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Texture: loam, clay loam, or sandy clay loam
Clay content: 20 to 35 percent
Rock fragments: 25 to 75 percent--0 to 15 percent cobbles; 25 to 60 percent pebbles
Calcium carbonate equivalent: 5 to 15 percent
Effervescence: strong or violent
Reaction: pH 7.8 to 8.4
COMPETING SERIES:
Bowbells (ND) - do not have more than 6 percent rock fragments in any horizon and do not have more than 25 percent rock fragments above a depth of 40 inches.
Carfall (MT) - are noncalcareous throughout the soil.
Centercreek (UT) - are noncalcareous throughout the soil; are mottled at depths between 20 to 40 inches.
Chugcreek (WY) - are noncalcareous throughout the profile; have lithic bedrock at a depth of 20 to 40 inches.
Detra (UT) - have hue of 7.5YR or 5YR in the Bt2 horizon; do not have more than 25 percent rock fragments above a depth of 40 inches.
Flaxton (ND) - have eolian sediments of sandy loam or loamy sand as thick as 40 inches over a loam or clay loam discontinuity; do not have more than 25 percent rock fragments above a depth of 40 inches.
Hereford (AZ) - do not have more than 25 percent rock fragments above a depth of 40 inches; are strongly effervescent in the lower part of the argillic horizon.
Hesperus (CO) - are noncalcareous throughout the profile.
Schauson (UT) - are noncalcareous throughout the profile.
Todachenne (NM) - have hues of 5YR or 7.5YR throughout the profile.
Weed (CO) - do not have more than 25 percent rock fragments above a depth of 40 inches.
GEOGRAPHIC SETTING:
Landform - alluvial fans and stream terraces.
Elevation - 3,000 to 3,500 feet.
Slope- 0 to 4 percent.
Parent material - loamy alluvium.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 15 to 19 inches.
Mean annual temperature - 40 to 45 degrees F.
Frost free period - 110 to 135 days.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Pachel soils are used mainly for nonirrigated crops. Potential native vegetation in uncultivated areas is mainly western wheat, big bluestem, green needlegrass, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Pachel soils are not extensive in southeastern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Fallon County, Montana, 1991.
REMARKS: Soil interpretations record: MT1231. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 22 inches (Ap and Bt horizons); an argillic horizon from 6 to 22 inches which is also the particle-size control section (Bt1 and Bt2 horizons). Pachel soils have a frigid temperature regime and an ustic moisture regime.