LOCATION VERNAL COEstablished Series
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive, mesic Ustic Haplargids
TYPICAL PEDON: Vernal loam, grassland. (Colors are for dry soil unless otherwise noted.)
A--0 to 4 inches; light brown (7.5YR 6/3) loam, dark brown (7.5YR 4/3) moist; moderate fine granular structure; weak platy structure in the upper 1/2 inch; soft, very friable, slightly sticky, slightly plastic; 5 percent pebbles; neutral (pH 7.2); clear smooth boundary. (3 to 5 inches thick)
BA--4 to 7 inches; reddish brown (5YR 5/3) heavy loam, reddish brown (5YR 4/3) moist; weak fine prismatic structure parting to moderate fine and very fine subangular blocks; slightly hard, very friable, slightly sticky, slightly plastic; primary peds are hard; few thin glossy patches on faces of peds and discontinuous glossy coatings on the inside of some root channels and pores; 5 percent pebbles; neutral (pH 7.2); clear smooth boundary. (0 to 4 inches thick)
Bt--7 to 20 inches; reddish brown (5YR 5/3) light clay loam reddish brown (5YR 4/3) moist; moderate medium prismatic structure parting to moderate medium subangular blocks; slightly hard, very friable, slightly sticky, slightly plastic; peds are very hard, firm; thin nearly continuous wax-like coatings on faces of peds and wax-like coatings and fillings on the inside of root channels and pores; 5 percent pebbles; slightly alkaline (pH 7.4); clear smooth boundary. (7 to 33 inches thick)
Bk--20 to 24 inches; light reddish brown (5YR 6/3) gravelly loam, reddish brown (5YR 5/3) moist; weak medium subangular blocky structure; hard, friable, slightly sticky, slightly plastic; peds are hard; visible secondary calcium carbonate occurring as concretions and in thin seams and streaks or as coatings on the surfaces of rock fragments; 25 percent pebbles; strongly effervescent; moderately alkaline (pH 8.2); gradual wavy boundary. (0 to 6 inches thick)
2Bk2--24 to 60 inches; very gravelly loamy sand; consistent accumulation of visible secondary calcium carbonate in the upper part of this horizon with the amount of calcium carbonate increasing with depth.
TYPE LOCATION: Montrose County, Colorado; approximately 1/4 mile east and 600 feet north of SW corner sec. 17, T. 47N., R. 8 W.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 48 to 52 degrees F., and mean summer soil temperature ranges from 67 to 71 degrees F. Depth to uniformly calcareous material normally ranges from 6 to 30 inches. Depth to the contrasting 2Bk2 horizon ranges from 20 to 40 inches. Depth to the base of the argillic horizon ranges from 12 to 40 inches. Depth to continuous subhorizons of visible secondary carbonate and/or sulfate ranges from 10 to 30 inches but such horizons are not strong enough to qualify as calcic or gypsic horizons. Exchangeable sodium percentage either remains constant or increases with increasing depth, ranging from 0 to 15 percent in the solum but exceeding 15 percent in the Bk horizon in some pedons. Subhorizons yellower than 5YR occur in some pedons but in a majority of the solum above the 2Bk horizon has hue of 5YR or redder. Rock fragments range from 0 to 35 percent by volume in a major part of the solum above the 2Bk horizon and range from 35 to 70 percent in the 2Bk horizon. These are mainly 1/2 to 10 inches in diameter.
The A horizon has hue of 7.5YR through 2.5YR, value of 5 through 8 dry, 3 through 7 moist, and chroma of 1 through 4. It is neutral or mildly alkaline.
The Bt horizon has hue of 5YR through 10R, value of 5 through 7 dry, 4 through 6 moist, and chroma of 1 through 6. Subhorizons yellower than 5YR occur in some pedons. This horizon is typically loam or clay loam but ranges in clay from 18 to 35 percent, silt from 15 to 55 percent, and sand from 20 to 60 percent with less than 35 percent being fine or coarser sand. It ranges from neutral through moderately alkalineThe 2Bk horizon has hue of 10YR through 2.5YR. It is moderately or strongly alkaline. Calcium carbonate equivalent of the fine earth ranges from about 3 to 14 percent.
COMPETING SERIES: Thes are the Larimer, Naturita, Tenorio, Wanetta, and Yoder series. Larimer, Naturita, and Wanetta soils have a hue of 7.5YR or yellower in the Bt horizon. Naturita and Tenorio soils have sand and gravel substratums at depths of less than 20 inches. Yoder soils are noncalcareous to depths of at least 40 inches and have a sand and gravel substratum at depths of less than 20 inches.
GEOGRAPHIC SETTING: Vernal soils are on terraces and alluvial fans. Slopes range from 0 to 6 percent. The soils formed in moderately thin, medium to moderately fine texture, calcareous materials overlying beds of gravelly or very gravelly loamy sand or sand. At the type location the mean annual precipitation is about 12 inches but ranges to 15 inches. Mean annual temperature is 48 degrees F., and mean summer temperature is 69 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Larimer and Naturita soils.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderate to rapid permeability.
USE AND VEGETATION: Used as grazing land or as dry or irrigated cropland. Native vegetation is sage, cactus, native bluegrass, and blue grama.
DISTRIBUTION AND EXTENT: Western Colorado. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Delta Montrose Area, Colorado, 1965.
REMARKS:
In October 2000, taxonomic classification was converted to the closest match found in Soil Taxonomy, Second Edition 1999. No update was made to horizon nomenclature, competing series section, etc. Other placements may be more appropriate after a complete update.