LOCATION LONNA              MT
Established Series
GFB-DRS-CJH
03/2000

LONNA SERIES


The Lonna series consists of very deep, well drained soils that formed in alluvium derived from semiconsolidated loamy sedimentary beds, and glaciofluvial and glaciolacustrine deposits. These soils are on alluvial fans, stream terraces, sedimentary plains, lake plains, drainageways, and hills. Slopes are 0 to 25 percent. Mean annual precipitation is about 11 inches, and mean annual temperature is about 44 degrees F.

TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Aridic Haplustepts

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

Ap--0 to 5 inches; brown (10YR 5/3) silt loam, brown (10YR 4/3) moist; moderate fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; slightly effervescent; slightly alkaline (pH 7.6); clear smooth boundary. (2 to 8 inches thick)

Bw--5 to 10 inches; pale brown (10YR 6/3) silt loam, brown (10YR 5/3) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine pores; disseminated lime; strongly effervescent; moderately alkaline (pH 8.0); clear smooth boundary. (5 to 8 inches thick)

Bk1--10 to 17 inches; light yellowish brown (2.5Y 6/4) silt loam, light olive brown (2.5Y 5/4) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine pores; disseminated lime; common fine threads and masses of lime; violently effervescent; moderately alkaline (pH 8.4); gradual smooth boundary. (5 to 17 inches thick)

Bk2--17 to 30 inches; light yellowish brown (2.5Y 6/4) silt loam, light olive brown (2.5Y 5/4) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; common very fine pores; disseminated lime; common fine threads and masses of lime; violently effervescent; strongly alkaline (pH 8.6); gradual smooth boundary. (6 to 25 inches thick)

BC--30 to 60 inches; pale yellow (2.5Y 7/4) silt loam, light yellowish brown (2.5Y 6/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; few very fine pores; disseminated lime; strongly effervescent; moderately alkaline (pH 8.4).

TYPE LOCATION: Rosebud County, Montana; 500 feet north and 1,400 feet east of the SW corner of sec. 19, T. 12 N., R. 44 E.

RANGE IN CHARACTERISTICS:

Soil temperature - 42 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 a depth of 20 inches is 41 degrees F or higher.

Control section - 18 to 35 percent clay.

Depth to Bk horizon - 10 to 16 inches.

EC and SAR- below a depth of 30 inches electrical conductivity ranges from 2 to 16 and the sodium adsorption ratio ranges from 10 to 30.

Soil phases - The noncalcareous phase has less than 5 percent calcium carbonate after mixing the surface 7 inches. The calcareous phase has 5 to 10 percent calcium carbonate.

A By horizon is allowed.

A or Ap horizon - Hue: 10YR or 2.5Y

Value: 5 or 6 dry; 3, 4, or 5 moist

Chroma: 2, 3, or 4

Texture: loam, silt loam, silty clay loam

Clay content: 18 to 35 percent

Effervescence: slightly or strongly; it has no effervescence in some uncultivated pedons

Calcium carbonate equivalent: 0 to 10 percent

Reaction: pH 6.6 to 8.4

Uncultivated areas have A horizons 2 to 4 inches thick.

Bw horizon - Hue: 10YR or 2.5Y

Value: 5 or 6 dry; 4 or 5 moist

Chroma: 2, 3, or 4

Texture: silt loam, silty clay loam

Clay content: 18 to 35 percent

Effervescence: slightly or strongly

Calcium carbonate equivalent: 0 to 10 percent

Reaction: pH 6.6 to 8.4

This horizon may be noneffervescent in some pedons.

Bk1 horizon - Hue: 10YR or 2.5Y

Value: 5, 6, or 7 dry; 4, 5, or 6 moist

Chroma: 2, 3, or 4

Texture: silt loam, silty clay loam

Clay content: 18 to 35 percent

Calcium carbonate equivalent: 5 to 12 percent

EC: 0 to 8 mmhos/cm

SAR: 0 to 13

Effervescence: strongly or violently

Reaction: pH 7.9 to 9.0

Bk2 horizon - Hue: 10YR or 2.5Y

Value: 5, 6, 7, or 8 dry; 4, 5, 6, or 7 moist

Chroma: 2, 3, or 4

Texture: silt loam, silty clay loam

Clay content: 18 to 35 percent

Calcium carbonate equivalent: 5 to 15 percent

EC: 0 to 8 mmhos/cm

SAR: 0 to 13

Effervescence: strongly or violently

Reaction: pH 7.9 to 9.0

BC horizon - Hue: 10YR or 2.5Y

Value: 5, 6, or 7 dry; 4, 5, or 6 moist

Chroma: 2, 3, or 4

Texture: very fine sandy loam, loam, silt loam, silty clay loam (may be stratified)

Clay content: 10 to 35 percent

EC: 2 to 16 mmhos/cm

SAR: 10 to 30

Effervescence: strongly or violently

Calcium carbonate equivalent: 5 to 15 percent

Reaction: pH 7.9 to 9.0

COMPETING SERIES:

Alona (MT) - is very strongly alkaline below a depth of 13 inches; has a sodium adsorption ratio greater than 13 at a depth of 13 inches; has a horizon of salt accumulation at depths of 22 inches.

Rahworth (MT) - is moderately alkaline in the control section; has a variegated subsoil below a depth of 23 inches that contains gypsum and salt.

GEOGRAPHIC SETTING:

Landform - alluvial fans; stream terraces; lake plains; drainageways; sedimentary plains; hills.

Elevation - 1,900 to 5,200 feet.

Slope- 0 to 25 percent.

Parent materials - alluvium derived from semiconsolidated, loamy sedimentary beds, glaciofluvial and glaciolacustrine deposits.

Climate - long, cold winters; moist springs; hot, dry summers.

Mean annual precipitation - 10 to 14 inches.

Mean annual temperature - 39 to 45 degrees F.

Frost-free period - 90 to 135 days.

GEOGRAPHICALLY ASSOCIATED SOILS:

DRAINAGE AND PERMEABILITY: Well drained, moderate permeability.

USE AND VEGETATION: Lonna soils are used mainly as rangeland, dryland pasture, and cropland. The potential native vegetation is western wheatgrass, needleandthread, green needlegrass, some forbs, and shrubs.

DISTRIBUTION AND EXTENT: Lonna soils are extensive on sedimentary uplands of eastern Montana.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado

SERIES ESTABLISHED: Stillwater County, Montana, 1975.

REMARKS: Soil interpretations record: MT0156. Reaction is by dye indicators. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 5 inches (Ap horizon); a cambic horizon from 5 to 17 inches (Bw, Bk1 horizons); accumulation of lime from 17 to 30 inches (Bk2 horizon); a particle-size control section from 10 to 40 inches (Bk1, Bk2, BC horizons). Lonna soils have a frigid temperature regime and an ustic moisture regime that borders on aridic.


National Cooperative Soil Survey
U.S.A.