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 OFFICE RESPONSIBLE: Salina, Kansas
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