LOCATION CONN                    MT

Established Series
Rev. HAL-KTS-RJS
03/2011

CONN SERIES

The Conn series consists of very deep, well drained soils that formed in alluvium. These soils are on stream terraces, alluvial fans and fan remnants. Slopes are 0 to 60 percent. Mean annual precipitation is about 12 inches and mean annual temperature is about 42 degrees F.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Aridic Haplustolls

TYPICAL PEDON: Conn loam, in cropland (colors are for dry soil unless otherwise noted).

Ap--0 to 7 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; weak medium granular structure; soft, friable, nonsticky and nonplastic; common very fine and fine roots; 5 percent gravel; neutral (pH 6.6); clear smooth boundary. (7 to 10 inches thick)

Bw--7 to 11 inches; yellowish brown (10YR 5/4) clay loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; common very fine and fine roots; many fine irregular pores; 5 percent gravel; slightly alkaline (pH 7.4); clear smooth boundary. (0 to 6 inches thick)

Bk1--11 to 21 inches; very pale brown (10YR 8/2) loam, very pale brown (10YR 7/4) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; many fine irregular pores; continuous distinct calcium carbonate coatings and casts on surface of gravel; common fine masses of calcium carbonate; violently effervescent; 5 percent gravel; moderately alkaline (pH 8.2); clear wavy boundary. (8 to 17 inches thick)

Bk2--21 to 34 inches; very pale brown (10YR 7/3) loam, brown (10YR 5/3) moist; weak fine subangular blocky structure; soft, friable, slightly sticky and nonplastic; few very fine and fine roots; common fine irregular pores; 5 percent gravel; continuous distinct calcium carbonate casts and coatings on surface of gravel; common fine masses of calcium carbonate; violently effervescent; moderately alkaline (pH 8.2). (10 to 20 inches thick)

Bk3--34 to 60 inches; very pale brown (10YR 7/3) gravelly loam, pale brown (10YR 6/3) moist; weak fine subangular blocky structure; soft, friable, nonsticky and nonplastic; few very fine and fine roots; common fine irregular pores; 15 percent gravel; continuous distinct calcium carbonate casts and coatings on surface of gravel; common fine masses of calcium carbonate; violently effervescent; moderately alkaline (pH 8.4).

TYPE LOCATION: Powell County, Montana; 300 feet north and 600 feet east of the SW corner of sec. 24, T.7 N., R.10 W.

RANGE IN CHARACTERISTICS:
Soil temperature - 41 to 46 degrees F.
Mollic epipedon thickness - 7 to 10 inches
Depth to calcic horizon - 11 to 18 inches

Ap horizon
Chroma: 1 to 3; dry or moist
Clay content: 18 to 27 percent
Rock fragments: 0 to 35 percent--0 to 15 percent gravel, 0 to 20 percent cobbles
Reaction: pH 4.5 to 7.4 (heavy metal phase - 4.5 to 6.0)

Bw horizon
Value: 4 to 6 dry; 4, or 5 moist
Chroma: 3 or 4; dry or moist
Texture: loam or clay loam
Clay content: 18 to 35 percent
Rock fragments: 0 to 15 percent gravel
Reaction: pH 6.6 to 7.8

Bk1 horizon
Value: 6 or 8 dry; 4 to 7 moist
Chroma: 2 to 4; dry or moist
Texture: loam, clay loam or sandy loam
Clay content: 18 to 35 percent
Rock fragments: 0 to 20 percent--0 to 15 percent gravel, 0 to 5 percent cobbles
Calcium carbonate equivalent: 15 to 40 percent
Reaction: pH 7.9 to 8.4

Bk2 horizon
Value: 5 to 8 dry; 4 to 6 moist
Chroma: 2 to 4; dry or moist
Texture: sandy loam, clay loam or loam
Clay content: 18 to 35 percent
Rock fragments: 0 to 25 percent--0 to 20 percent gravel, 0 to 5 percent cobbles
Calcium carbonate equivalent: 15 to 30 percent
Reaction: pH 7.9 to 8.4

Bk3 horizon
Value: 5 to 8 dry; 4 or 6 moist
Chroma: 3 or 4; dry or moist
Texture: sandy loam or loam
Clay content: 18 to 27 percent
Rock fragments: 0 to 25 percent--0 to 20 percent gravel, 0 to 5 percent cobbles
Calcium carbonate equivalent: 15 to 25 percent
Reaction: pH 7.9 to 8.4

COMPETING SERIES:
Anamac (MT) - does not have a calcic horizon
Boxwell (MT) - have a paralithic contact at depths of 20 to 40 inches
Fortbenton (MT) - have a lithologic discontinuity
Kremlin (MT) - does not have a calcic horizon
Littlemo (ND) - have a lithologic discontinuity
Waterhill (UT) - does not have a calcic horizon

GEOGRAPHIC SETTING:
Landform - stream terraces, alluvial fans and fan remnants
Elevation - 3,600 to 6,500 feet
Slope - 0 to 60 percent
Parent material - alluvium
Climate - long, cold winters; moist springs; warm summers
Mean annual precipitation - 10 to 14 inches
Mean annual temperature - 39 to 44 degrees F.
Frost-free period - 80 to 105 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Varney and Sixbeacon soils which occur on similar landforms. Varney soils have an argillic horizon. Sixbeacon soils are loamy-skeletal.

DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.

USE AND VEGETATION: Conn soils are used as nonirrigated and irrigated cropland and rangeland. Potential native vegetation is mainly bluebunch wheatgrass, green needlegrass, needleandthread, fringed sagewort, and Sandberg bluegrass.

DISTRIBUTION AND EXTENT: Conn soils are of small extent in western Montana valleys. MRLAs - 43B, 44B, 46.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.

SERIES ESTABLISHED: Powell County, Montana, 1995.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 7 inches (Ap horizon
Calcic horizon - from 11 to 60 inches (Bk1, Bk2 and Bk3 horizons)
Particle-size control section - from 10 to 40 inches (Bk1, Bk2, and part of Bk3 horizons).

Conn soils have a frigid temperature regime and an ustic moisture regime that borders on aridic.

ADDITIONAL DATA: Soil interpretations record - MT1494. As of 2/9/2010 the series name was changed from Con to Conn because the Con name could not be used in the new system for official series descriptions.

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National Cooperative Soil Survey
U.S.A.