LOCATION MAGS               CO
Tentative Series
Rev. MJB/DAD/SSP
03/2004

MAGS SERIES


The Mags series consists of very deep, well drained soils that formed in slope alluvium over residuum derived from interbedded sandstone and shale. Mags soils are on structural benches and summits of mesas. Slopes range from 3 to 15 percent. Mean annual precipitation is about 11 inches and the mean annual temperature is about 48 degrees F.

TAXONOMIC CLASS: Fine, mixed, superactive, mesic Ustic Haplargids

TYPICAL PEDON: Mags fine sandy loam, 4 percent slope at an elevation of 6520 feet in rangeland. (Colors are for dry soil unless otherwise noted.)

A--0 to 2 inches (0 to 6 cm); light brown (7.5YR 6/3) fine sandy loam, brown (7.5YR 4/3) moist; weak fine granular structure; soft, friable, slightly sticky and slightly plastic; common fine and medium roots; noneffervescent; slightly alkaline (pH 7.4); abrupt wavy boundary. (2 to 4 inches thick)

BE--2 to 5 inches (6 to 13 cm); pinkish gray (7.5YR 7/2) fine sandy loam, brown (7.5YR 5/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and medium roots; noneffervescent; slightly alkaline (pH 7.6); clear wavy boundary. (0 to 3 inches thick)

Bt1--5 to 11 inches (13 to 29 cm); brown (7.5YR 5/3) clay loam, brown (7.5YR 4/3) moist; weak medium prismatic structure parting to moderate medium subangular blocky; hard, firm, moderately sticky and moderately plastic; common fine roots; 75 percent distinct clay films in pores and on faces of peds; slightly effervescent; moderately alkaline (pH 8.2); clear wavy boundary.

Bt2---11 to 24 inches (29 to 61 cm); brown (7.5YR 5/3) clay, brown (7.5YR 4/2) moist; weak medium prismatic structure parting to moderate medium subangular blocky; hard, firm, moderately sticky and very plastic; few fine roots; 75 percent distinct clay films in pores and faces of peds; slightly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (Total thickness of the Bt horizon is 5 to 20 inches.)

Btk1--24 to 32 inches (61 to 81 cm); light brown (7.5YR 6/3) clay, brown (7.5YR 5/2) moist; moderate medium subangular blocky structure; hard, very firm, moderately sticky and very plastic; few fine roots; 30 percent distinct clay films in pores and on faces of peds; 15 percent fine masses and threads of calcium carbonate, 10 percent calcium carbonate equivalent, strongly effervescent; moderately alkaline (pH 8.2); gradual wavy boundary.

Btk2--32 to 39 inches (81 to 100 cm); light brown (7.5YR 6/3) sandy clay loam, light brownish gray (10YR 6/2) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; 5 percent faint clay films on faces of peds; 10 percent fine masses of calcium carbonate, 8 percent calcium carbonate equivalent, violently effervescent; moderately alkaline (pH 8.2); gradual wavy boundary. (Total thickness of the Btk horizon is 4 to 40 inches.)

BCk--39 to 80 inches (100 to 203 cm); light yellowish brown (10YR 6/4) sandy clay loam, pale brown (10YR 6/3) moist; weak fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; 2 percent very fine masses of calcium carbonate, 5 percent calcium carbonate equivalent, strongly effervescent; moderately alkaline (pH 8.2). (0 to 42 inches thick)

TYPE LOCATION: Montrose County, Colorado; located about 1950 feet west and 1300 feet south of the northeast corner of sec. 34, T. 49 N., R. 11 W.; Dry Creek Basin USGS quad; lat. 38 degrees 28 minutes 17 seconds N. and long. 108 degrees 5 minutes 1 second W., NAD 83.

RANGE IN CHARACTERISTICS:

Soil moisture: The soil moisture control section is affected by precipitation that is evenly distributed throughout the year, with the exception of a slight increase in the spring and a significant increase in late summer. Aridic moisture regime bordering on ustic.
Mean annual soil temperature: 49 to 51 degrees F
Depth to argillic horizon: 2 to 7 inches
Depth to secondary calcium carbonate: 19 to 24 inches

Particle-size control section (weighted average):
Clay content: 35 to 42 percent
Rock fragments: 0 to 10 percent shale and sandstone parachanners

A horizon:
Hue: 7.5YR
Value: 4 to 6 dry or moist
Chroma: 2 or 3 dry or moist
Texture: fine sandy loam
Clay content: 15 to 18 percent
Rock fragments: 0 to 12 percent channers, 0 to 1 percent flagstones
Calcium carbonate equivalent: 0 to 5 percent
Reaction: slightly alkaline

BA or BE horizon (where present):
Hue: 7.5YR
Value: 4 or 7 dry or moist
Chroma: 2 or 3 dry or moist
Texture: fine sandy loam, sandy loam
Clay content: 18 to 20 percent
Rock fragments: 0 to 10 percent channers
Calcium carbonate equivalent: 0 to 5 percent
Reaction: slightly alkaline

Bt or Btk horizon:
Hue: 7.5YR or 10YR
Value: 4 to 7 dry, 4 to 6 moist
Chroma: 2 or 3 dry or moist
Texture: sandy clay loam, clay loam, clay
Clay content: 32 to 42 percent
Pararock fragments: 0 to 10 percent sandstone or shale parachanners
Calcium carbonate equivalent:<p> 0 to 5 percent in Bt; 5 to 14 percent in Btk Reaction: moderately alkaline)

C horizon (where present):
Hue: 10YR
Value: 5 or 6 dry or moist
Chroma: 2 to 4 dry or moist
Texture: sandy clay loam, clay loam
Clay content: 30 to 33 percent
Pararock fragments: 0 to 10 percent sandstone or shale parachanners
Reaction: moderately alkaline

COMPETING SERIES: These are the Chafin, Hawaikuh, Lonti, Padilla, Servilleta, Silver, and Tobish soils.

Chafin: do not have secondary carbonates
Hawaikuh, Padilla: have hues 5YR or redder
Lonti: have up to 35 percent rock fragments in the particle size control section and are moister
Servilleta, Tobish: have lithic contacts between 20 and 40 inches deep
Silver: have calcic horizons below 40 inches and have basalt fragments

GEOGRAPHIC SETTING:
Parent material: slope alluvium derived from sandstone and shale
Landform: structural benches and summits of mesas
Slopes: 3 to 15 percent
Elevation: 5500 to 7300 feet
Mean annual temperature: 47 to 49 degrees F
Mean annual precipitation: 10 to 12 inches
Precipitation pattern: The soil moisture control section is affected by precipitation that is evenly distributed throughout the year, with the exception of a slight increase in the spring and a significant increase in late summer.
Frost-free period: 125 to 145 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lazear and Blancot soil series. The Lazear soils are very shallow or shallow to bedrock and do not have an argillic horizon. Blancot soils have a fine-loamy particle size control section.

DRAINAGE AND PERMEABILITY: well drained, moderate to high runoff, moderate permeability.

USE AND VEGETATION: Used mainly for livestock grazing. Present vegetation includes galleta, western wheatgrass, needleandthread, Wyoming big sagebrush, shadscale, some Utah juniper and scattered pinyon pine.

DISTRIBUTION AND EXTENT: Uncompahgre Plateau, western Colorado; LRR D, MLRA 36; minor extent.

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

SERIES PROPOSED: Montrose County, Colorado, Ridgway soil survey area. The name is coined.

REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Particle-size control section: The zone from 5 to 25 inches. (Bt1, Bt2, Btk1 horizons)
Ochric epipedon: The zone from 0 to 5 inches. (A, BE horizons)
Argillic horizon: The zone from 5 to 39 inches. (Bt1, Bt2, Btk1, Btk2 horizons)
Secondary carbonates: The zone from 24 to 60 inches. (Btk and BCk horizons)

The assignment of the cation-exchange activity class is inferred from lab data from similar soils in the surrounding area.

Taxonomic Version: Second Edition, 1999.


National Cooperative Soil Survey
U.S.A.