LOCATION JEMCO COEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Typic Haplustalfs
TYPICAL PEDON: Jemco silt loam , on a northeast facing, simple, 3 percent slope in ponderosa pine woodland at an elevation of 8290 feet. (Colors are for dry soil unless otherwise noted.) Described on July 31, 1980.
A1--0 to 2 inches; brown (10YR 5/3) silt loam, dark brown (7.5YR 3/2) moist; weak fine granular structure; soft, friable, nonsticky and nonplastic; neutral (pH 6.6); clear smooth boundary. (2 to 6 inches thick)
A2--2 to 7 inches; brown (7.5YR 5/2) silt loam, dark brown (7.5YR 3/2) moist; weak medium subangular blocky structure that parts to weak fine granular; slightly hard, very friable, slightly sticky and non plastic; slightly acid (pH 6.4); clear wavy boundary. (0 to 5 inches thick)
BE--7 to 14 inches; light reddish brown (5YR 6/4) loam, reddish brown (5YR 4/3) moist; weak medium subangular blocky structure; hard, very friable, slightly sticky and non plastic; slightly acid (pH 6.2); gradual wavy boundary. (0 to 8 inches thick)
Bt1--14 to 22 inches; brown (7.5YR 5/4) loam, reddish brown (5YR 4/3) moist; weak medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; few distinct clay films on faces of peds and in root channels and pores; slightly acid (pH 6.2); gradual wavy boundary.
Bt2--22 to 35 inches; reddish brown (5YR 5/4) clay loam, dark reddish brown (5YR 3/4) moist; moderate medium subangular blocky structure; hard, friable, very sticky and moderately plastic; few distinct clay films on faces of peds; slightly acid (pH 6.2); gradual wavy boundary.
2Bt3--35 to 39 inches; yellowish red (5YR 4/6) clay loam, yellowish red (5YR 4/6) moist; moderate medium angular blocky structure; very hard, friable, very sticky and moderately plastic; few prominent clay films on faces of peds and in pores; slightly acid (pH 6.1); abrupt wavy boundary. (combined thickness of the Bt horizons is 14 to 34 inches)
2R--39 inches; hard fractured sandstone bedrock, weathered in upper inch.
TYPE LOCATION: Dolores County, Colorado; about 18 miles north of Dolores, Colorado; located about 1,200 feet E and 2,100 feet N of the southwest corner of sec. 27, T. 40 N., R. 16 W.; Narraguinnep Mountain USGS quad; lat. 37 degrees 41 minutes 48 seconds N. and long. 108 degrees 36 minutes 28 seconds W., NAD 27
RANGE IN CHARACTERISTICS:
Soil moisture: ustic moisture regime (typic ustic subclass)
Mean annual soil temperature: 42 to 47 degrees F.
Mean summer soil temperature: 59 to 61 degrees F.
Depth to lithic contact: 20 to 40 inches to sandstone from the mineral soil surface
Thickness of the argillic horizon: 14 to 34 inches
Thickness of the ochric epipedon: 3 to 8 inches
Some pedons have an Oe horizon that may range from 1 to 2 inches thick
Particle-size control section (weighted average):
Clay content: 18 to 35 percent
A horizon:
Hue: 7.5YR or 10YR
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 2 or 3, dry or moist
Texture: Loam, Silt loam
Reaction: slightly acid (pH 6.1) to neutral (pH 7.3)
BE horizon (an E horizon in some pedons):
Hue: 5YR or 7.5YR
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 3 or 4, dry or moist
Texture: Loam, Silt loam
Reaction: slightly acid (pH 6.1) to neutral (pH 7.3)
Bt horizon:
Hue: 5YR or 7.5YR
Value: 4 to 7 dry, 3 or 4 moist
Chroma: 4 to 6 dry or moist
Texture: Loam, Clay loam, or Silty clay loam
Rock fragments: 0 to 2 percent sandstone fragments.
Reaction: slightly acid (pH 6.1) to neutral (pH 7.3)
2Bt horizon:
Hue: 5YR or 7.5YR
Value: 4 to 6 dry, 3 or 4 moist
Chroma: 4 to 6 dry or moist
Texture: Clay loam or Sandy clay loam
Rock fragments: 0 to 5 percent sandstone fragments.
Reaction: slightly acid (pH 6.1) to neutral (pH 7.3)
COMPETING SERIES: Current competitors are the: Alderon, Allens Park, Bayerton, Belltower, Elbeth, Elbuck, Elmark, Hoyt, Kunz, Lumpgulch, Northrim, Plome, Rule, Shoemaker, Sweetweed, and Tunitcha series. Other soils that may be competitors when their classification is updated are the: Eaglecreek, and Jemez series.
Alderon and Elmark and Lumpgulch: formed in parent material weathered from granite.
Allens Park and Rule: have a precipitation pattern with most of the precipitation falling in the spring and summer.
Bayerton: have horizons of secondary calcium carbonate accumulation.
Belltower: has a paralithic contact at 20 to 40 inches
Eaglecreek: have 5 to 25 percent igneous rock fragments in the particle size control section and formed from igneous parent material
Elbeth, Elbuck, Hoyt, Kunz, Northrim, Plome, and Sweetweed: do not have a lithic contact above 40 inches
Jemez: formed in parent materials derived from tuff and are more alkaline
Shoemaker: have redox concentrations in the lower part of the argillic horizon
Tunitcha: have a paralithic contact with sandstone at 40 to 60 inches
GEOGRAPHIC SETTING:
Parent material: eolian deposits over residuum derived from sandstone.
Landform: mesas and hills.
Slopes: 1 to 15 percent
Elevation: 7,800 to 8,500 feet
Mean annual air temperature: 40 to 46 degrees F.
Mean annual precipitation: 18 to 22 inches.
Wettest months: July and August receive slightly more precipitation than other months.
Driest months: May and June receive the least precipitation, however the soils are moist through mid June from snowmelt.
Frost-free period: 70 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Beje, Burnson, and Detra series. All are on mesas and hillslopes.
Beje soils are shallow.
Burnson soils are deep and have fine textured argillic horizons.
Detra soils are deep and have thick mollic epipedons.
DRAINAGE AND PERMEABILITY: Well drained, low runoff, moderately slow permeability.
USE AND VEGETATION: The major uses are commercial woodland, wildlife habitat, and livestock grazing. The native vegetation consists of ponderosa pine with an understory of Gambel's oak, snowberry, Arizona fescue, mountain brome, western wheatgrass, and Columbia needlegrass.
DISTRIBUTION AND EXTENT: Southwest Colorado. LRR E, MLRA 48A. This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Cortez Soil Survey Area, Colorado, 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 7 inches. (A1 and A2 horizons) The soil is dark enough but not thick enough for a mollic epipedon.
Argillic horizon: The zone from 14 to 39 inches. (Bt1, Bt2, and 2Bt3 horizons)
Lithic contact: Hard fractured sandstone bedrock at 39 inches.
Particle-size control section: The zone from 14 to 34 inches. (Bt1 and Bt2 horizons)
Keys to Soil Taxonomy: Classified according to the Eighth Edition, 1998
Activity class is presumed based on general trend of other soils in the area.