LOCATION VALMONT COEstablished Series
TAXONOMIC CLASS: Clayey over loamy-skeletal, smectitic, mesic Aridic Argiustolls
TYPICAL PEDON: Valmont loam in grasslands. (Colors are for dry soil unless otherwise noted.)
A1--0 to 10 centimeters (0 to 4 inches); grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, very friable; 5 percent pebbles; neutral (pH 7.0); clear smooth boundary. (8 to 15 centimeters (3 to 6 inches) thick)
B1--10 to 18 centimeters (4 to 7 inches); brown (10YR 5/3) clay loam, dark brown (10YR 3/3) moist; weak medium prismatic structure parting to moderate medium subangular blocky; hard, friable, sticky, plastic; few thin glossy patches on vertical faces of some peds; 10 percent pebbles; neutral (pH 7.2); clear smooth boundary. (5 to 10 centimeters (2 to 4 inches) thick)
Bt--18 to 51 centimeters (7 to 20 inches); brown (10YR 5/3) light clay, brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate medium angular blocky; extremely hard, firm, very sticky, very plastic; thin continuous wax-like coatings on faces of peds; wax-like linings and fillings in root channels; 10 percent pebbles; slightly alkaline (pH 7.4); clear wavy boundary. (15 to 43 centimeters (6 to 17 inches) thick)
Bk--51 to 61 centimeters (20 to 24 inches); light brown (7.5YR 6/3) gravelly clay loam, brown (7.5YR 5/3) moist; weak medium prismatic structure parting to medium subangular blocky; very hard, firm, sticky, plastic; common thin glossy patches on faces of peds; weak glossy coatings inside pores; 15 percent pebbles; visible secondary calcium carbonate occurring as concretions and in thin seams and streaks; calcareous; moderately alkaline (pH 8.2); gradual wavy boundary. (10 to 36 centimeters (4 to 14 inches) thick)
2Ck1--61 to 89 centimeters (24 to 35 inches); pinkish white (7.5YR 8/2) very gravelly loam, pink (7.5YR 8/4) moist; massive; very hard, very friable, slightly plastic; 50 percent pebbles and cobble; visible calcium carbonate occurring in finely divided marl-like form; calcareous; moderately alkaline (pH 8.4); gradual wavy boundary. (25 to 51 centimeters (10 to 20 inches) thick)
2Ck2--89 to 152 centimeters (35 to 60 inches); light brown (7.5YR 6/3) very gravelly loam, brown (7.5YR 5/3) moist; massive; hard, very friable; 50 to 75 percent pebbles and cobble; visible secondary calcium carbonate occurring as concretions, and as coatings on the underside of pebbles and cobble fragments; calcareous; moderately alkaline (pH 8.4).
TYPE LOCATION: Boulder County, Colorado; 244 meters (800 feet) east of the northwest corner of Sec. 7, T. 3 N., R. 69 W.
RANGE IN CHARACTERISTICS:
Mollic epipedon: 18 to 48 centimeters (7 to 19 inches) thick
Base of the argillic horizon: deeper than 46 centimeters (18 inches) below the surface
When undisturbed; depth to calcareous material normally 20 to 51 centimeters (8 to 20 inches)
Organic carbon content mollic epipedon: .7 to 2.0 percent
Argillic horizon averages 35 to 60 percent clay and more than 15 percent but less than 35 percent fine or coarser sand
Coarse fragments content: 0 to 15 percent in the solum but exceeds 35 percent in some parts of the C horizon between 51 to 102 centimeters (20 and 40 inches)
Mean annual soil temperature: 8 to 14 degrees C. (47 to 58 degrees F.)
Mean summer soil temperature: 15 to 26 degrees C. (59 to 79 degrees F.)
Soil temperature at 51 centimeters (20 inches) 5 degrees C. (41 degrees F. or higher for about 230 to 305 days
Soil moisture control section: moist in some parts when the soil temperature at 51 centimeters (20 inches) is 5 degrees C. (41 degrees F.) or higher, for about 56 to 152 days
A horizon:
Hue: 5Y to 7.5YR
Value: 4 or 5, 2 or 3 moist
Chroma: 1 to 3
Reaction: slightly acid to mildly alkaline
Structure: Primary granular structure but is subangular blocky in some pedons
Rupture resistance: soft to slightly hard
B2t horizon:
Hue: 5Y to 7.5YR
Value: 4 to 7, 3 to 6 moist
Chroma: 2 to 5
Reaction: slightly acid to moderately alkaline
Structure: primarily prismatic but subangular or angular blocky structure in some pedons
Texture: heavy clay loam or light clay
Clay content: 35 to 60 percent
Silt content: 15 to 45 percent
Sand content: 15 to 45 percent with more than 15 but less than 35 percent being fine or coarser sand
2C horizon:
Hue: 5Y to 7.5YR
Reaction: moderately alkaline to strongly alkaline
Calcium carbonate equivalent: 15 to 35 percent
Texture: very gravelly loam or clay loam with matrix material having more than 18 percent but less than 35 percent clay
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform: old alluvial fans or high terraces
Parent material: very gravelly calcareous alluvial parent sediments derived from a variety of rocks
Slope: 0 to about 10 percent
Average annual precipitation: 33 to 43 centimeters (13 to 17 inches) with peak periods of rainfall during the spring and summer months
Mean annual temperature: 9 degrees C. (48 degrees F.)
Mean summer temperature: 20 degrees C. (68 degrees F.)
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Nederland and
Nunn soils.
Nederland soils are coarser textured and contain more gravel in the solum.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage: well drained
Runoff: medium
Saturated Hydraulic Conductivity: moderately high to high.
USE AND VEGETATION: Used as native pastureland or irrigated cropland.
Principal native vegetation is blue grama, western wheatgrass, and cactus.
DISTRIBUTION AND EXTENT: Present known distribution is limited to the central portion of Colorado on high benches fronting the Front Range. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Boulder Area, Colorado, 1971.
REMARKS:
Soils last updated by the state 2/80.
Modified format by LRM in 6/2006 to include metric conversion and change permeability to saturated hydraulic conductivity.
Changed B2t to Bt, B3ca to Bk, 2CCa to 2Ck1 and C2ca to 2Ck2 9/2006. It appears the 2C horizons may have a calcic horizon depending on the underlying material. JCR