LOCATION MADIGAN MT

Established Series
Rev. GFB-KTS-RJS
01/2012

MADIGAN SERIES

The Madigan series consists of moderately deep, well drained soils that formed in slope alluvium or colluvium over residuum derived from igneous rock. These soils occur on hills and mountain slopes. Slopes are 2 to 45 percent. The mean annual precipitation is about 16 inches, and the mean annual air temperature is about 38 degrees F.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive Calcic Argicryolls

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

A--0 to 5 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; slightly hard, very friable, nonsticky and nonplastic; many very fine and few fine roots; common very fine and fine tubular pores; 5 percent gravel; neutral (pH 6.8); clear smooth boundary. (5 to 7 inches thick)

Bt1--5 to 10 inches; dark grayish brown (10YR 4/2) clay loam, dark brown (10YR 3/3) moist; strong coarse subangular blocky structure; very hard, very firm, moderately sticky and very plastic; many very fine and few fine roots; common very fine and fine tubular pores; many distinct clay films on faces of peds and on surface of rock fragments; 10 percent gravel; neutral (pH 7.2); clear smooth boundary.

Bt2--10 to 19 inches; grayish brown (10YR 5/2) clay loam, dark grayish brown (10YR 4/2) moist; strong medium subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; common very fine and few fine roots; common very fine and fine tubular pores; 5 percent gravel; neutral (pH 7.2); clear wavy boundary. (combined thickness of Bt1, Bt2 horizons - 6 to 20 inches)

Bk--19 to 27 inches; light gray (2.5Y 7/2) gravelly loam, light brownish gray (2.5Y 6/2) moist; weak very coarse subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; few fine roots; few interstitial pores; 20 percent gravel; finely disseminated calcium carbonate and common soft masses of calcium carbonate; violently effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (5 to 10 inches thick)

Cr--27 to 38 inches; light gray (2.5Y 7/2) semi-consolidated grus that crushes to loamy sand, light brownish gray (2.5Y 6/2) moist; strongly effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (0 to 20 inches thick)

R--38 inches; hard igneous bedrock.

TYPE LOCATION: Beaverhead County, Montana; 2000 feet south and 2200 feet east of the NW corner of sec. 1, T. 8S, R. 11W; Bannack topographic quadrangle; UTM 12T, 350863e, 5003346n.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 38 to 42 degrees F.
Thickness of the mollic epipedon - 7 to 15 inches
Depth to top of argillic horizon - 5 to 7 inches
Depth to calcic horizon - 11 to 22 inches
Depth to paralithic contact - 25 to 39 inches
Depth to lithic contact - 30 to 40 inches

A horizon
Hue: 2.5Y, 10YR or 7.5YR; dry or moist
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Texture: sandy loam or loam
Clay content: 15 to 25 percent
Rock fragment content: 0 to 35 percent--0 to 25 percent gravel, 0 to 10 percent cobbles
Reaction: pH 6.6 to 7.6

Bt1, Bt2 horizons
Hue: 2.5Y, 10YR or 7.5YR; dry or moist
Value: 4 to 6 dry; 3 to 5 moist
Chroma: 2 to 6; dry or moist
Texture: sandy clay loam, loam or clay loam
Clay content: 22 to 35 percent
Rock fragment content: 0 to 35 percent--0 to 25 percent gravel, 0 to 10 percent cobbles
Reaction: pH 6.6 to 7.6

Bk horizon
Hue: 2.5Y, 10YR or 7.5YR; dry or moist
Value: 6 or 7 dry; 5 or 6 moist
Chroma: 2 or 3; dry or moist
Texture: sandy loam, sandy clay loam, loam or clay loam
Clay content: 15 to 30 percent
Rock fragment content: 10 to 35 percent--10 to 25 percent gravel, 0 to 10 percent cobbles
Calcium carbonate equivalent: 15 to 30 percent
Reaction: pH 7.9 to 8.6

COMPETING SERIES:
Accola (MT) - are very deep
Elispring (MT) - have hues redder than 7.5YR
Gebson (CO) - are very deep
Glentivar (CO) - are deep to a paralithic contact
Michelson (MT) - are very deep
Monida (ID) - are very deep
Morset (CO) - are very deep
Northorn (UT) - are very deep
Oro Fino (MT) - are very deep
Philipsburg (MT) - are very deep

GEOGRAPHIC SETTING:
Landform - hills and mountain slopes
Elevation - 5,000 to 7,500 feet
Slope - 2 to 45 percent
Parent material - slope alluvium or colluvium over residuum derived from igneous rock
Climate - long, cold winters; moist springs; warm summers
Mean annual precipitation - 15 to 19 inches
Mean annual air temperature - 36 to 45 degrees F.
Frost-free period - 30 to 70 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Blaine, Nieman, and Dalys soils. The Blaine soils are loamy-skeletal and are found mainly on backslopes of hills; the Nieman soils are shallow (10 to 20 inches) to bedrock, the Dalys soils are very shallow (3 to 10 inches) to bedrock and both are found mainly on summits and shoulders of hills.

DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.

USE AND VEGETATION: Madigan soils are used mainly for rangeland. Native vegetation is mainly Idaho fescue, bluebunch wheatgrass, prairie junegrass, rubber rabbitbrush, fringed sagewort, phlox and big sage.

DISTRIBUTION AND EXTENT: Madigan soils are of small extent in southwestern Montana. MLRA - 43B.

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

SERIES ESTABLISHED: Horse Prairie-South Valley Area - Part of Beaverhead County, Montana, 2011; proposed in Beaverhead County, Montana, 2003.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 10 inches (A, Bt1 horizons)
Argillic horizon - from 5 to 19 inches (Bt1, Bt2 horizons)
Calcic horizon - from 19 to 27 inches (Bk horizon)
Paralithic contact - at 27 inches (Cr horizon)
Lithic contact - at 38 inches (R horizon)
Particle-size control section - from 5 to 19 inches (Bt1, Bt2 horizons)

Madigan soils have a cryic temperature regime and an ustic moisture regime.

National Cooperative Soil Survey
U.S.A.