LOCATION POUDRE CO
Established Series
Rev. AJC-KLS
05/2023
POUDRE SERIES
The Poudre series consists of very deep, poorly or somewhat poorly drained soils that formed in calcareous alluvium derived mainly from micaceous schist and gneiss. Poudre soils are on terraces, floodplains, and in drainageways. Slopes are 0 to 6 percent. Mean annual precipitation is about 355 mm and the mean annual air temperature is about 8 degrees C.
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, calcareous, mesic Cumulic Endoaquolls
TYPICAL PEDON: Poudre fine sandy loam - grassland. (Colors are for dry soil unless otherwise noted.)
A--0 to 25 cm; gray (10YR 5/1) fine sandy loam, very dark gray (10YR 3/1) moist; moderate medium granular structure; slightly hard, very friable, nonsticky, nonplastic; crushed soil surfaces feel slippery and soap-like; many medium and large mica flakes; calcareous; moderately alkaline (pH 8.0); clear wavy boundary. (15 to 30 cm thick)
Ag--25 to 76 cm; grayish brown (10YR 5/2) fine sandy loam, very dark grayish brown (10YR 3/2) moist; common medium distinct dark yellowish brown (10YR 4/4) moist and dark yellowish brown (10YR 4/6) moist mottles; weak medium subangular blocky structure that parts to coarse granules; slightly hard, very friable, nonsticky, nonplastic; crushed soil surfaces feel slippery and soap-like; many fine to large mica flakes; calcareous; moderately alkaline (pH 8.0); gradual smooth boundary. (30 to 112 cm thick)
Bg--76 to 152 cm; light brownish gray (10YR 6/2) fine sandy loam, grayish brown (10YR 5/2) moist; many large promiment light yellowish brown (10YR 6/4) moist mottles; massive; slightly hard, friable, nonsticky, nonplastic; crushed soil surfaces feel slippery and soap-like; many fine to large mica flakes; calcareous; moderately alkaline (pH 8.0).
TYPE LOCATION: Larimer County, Colorado; approximately 30 meters east of W 1/4 corner of sec. 34, T. 8 N., R. 69 W.
RANGE IN CHARACTERISTICS:
Depth to uniformly calcareous material - 0 to 25 cm
Exchangeable sodium percentage - 0 to 15 percent
Electrical conductivity - 0 to 14 millimhos in a major part of the control section; no subhorizons more than 8 cm thick above a depth of 50 cm exceed these limits.
Particle-size control section:
Mollic epipedon thickness - 60 to 125 cm thick
Clay content - 5 to 18 percent
Sand content - 45 to 80 percent, with more than 35 percent being fine or coarser sand and excluding textures of loamy fine sand or coarser
Sand and silt fractions contain 2 to 20 percent or more mica platelets of sufficient size to affect the physical properties of the soil.
Continuous concentrated horizons of visible secondary calcium carbonate and/or sulfate do not occur within the control section.
Rock fragment content - 0 to 15 percent, mainly 15 to 250 mm in diameter
A horizons
Hue: 5Y through 7.5YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 0 through 2, dry or moist
Reaction: pH 7.4 to 9.0
Bg horizon
Hue: 5Y through 7.5YR; subhorizons redder than 7.5YR occur in some pedons
Texture: fine sandy loam, sandy loam
Calcium carbonate equivalent percentage: 0 to 4 percent
Reaction: pH 7.9 to 9.0
COMPETING SERIES: None listed.
GEOGRAPHIC SETTING:
Landscape - terraces, floodplains, and drainageways
Elevation - 1,525 to 2,100 meters
Slopes - 0 to 6 percent
Parent material - calcareous alluvium derived mainly from micaceous schist and gneiss
Mean annual air temperature - 8 to 10 degrees C
Mean annual precipitation - 330 to 430 mm
Precipitation pattern - peak periods of precipitation in the spring and early summer months
Frost-free period - 110 to 150 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Somewhat poorly or poorly drained; slow or very slow runoff; moderate or rapid permeability.
USE AND VEGETATION: Poudre soils are used as grazing land or as hay meadows. Native vegetation is willows, sedges, timothy, and bluegrass.
DISTRIBUTION AND EXTENT: Poudre soils are of small extent in the foothills along the eastern front of the Rocky Mountains in Colorado; MLRA 49.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Delta Montrose Area, Colorado, 1965.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 76 cm (A and Ag horizons)
Aquic conditions - 25 to 152 cm (Ag and Bg horizons)
Particle-size control section - 25 to 100 cm (Ag horizon and part of the Bg horizon)
Poudre soils have a mesic soil temperature regime and an ustic soil moisture regime bordering on aridic.
Converted to metric, formatting updated to current standards, and competing series section updated. 05/2020
National Cooperative Soil Survey
U.S.A.