LOCATION CALKINS COEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, mesic Cumulic Haplaquolls
TYPICAL PEDON: Calkins sandy loam - grassland. (Colors are for dry soil unless otherwise noted.)
A11--0 to 14 inches; grayish brown (10YR 5/2) sandy loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, very friable; neutral (pH 7.0); clear smooth boundary. (10 to 20 inches thick)
A12g--14 to 40 inches; grayish brown (10YR 5/2) sandy loam, very dark grayish brown (10YR 3/2) moist; weak coarse subangular blocky structure that parts to fine granules; slightly hard, very friable; common medium distinct mottles of brown (7.5YR 5/4) moist; neutral (pH 7.0); gradual wavy boundary. (4 to 30 inches thick)
B2g--40 to 60 inches; light brownish gray (10YR 6/2) sandy loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, very friable; common medium distinct mottles of brown (7.5YR 5/4) moist; neutral (pH 7.2).
TYPE LOCATION: Boulder County, Colorado; approximately 400 feet north and 300 feet east of the center of Sec. 17, T. 1 S., R. 69 W.
RANGE IN CHARACTERISTICS: The mollic epipedon is 24 to 50 inches thick, and the solum is more than 40 inches thick. Content of organic carbon in the mollic epipedon ranges from .8 to 3 percent and decreases uniformly with depth. Exchangeable sodium is normally less than 3 percent, but ranges to 14 percent in any subhorizon above 40 inches. Content of salts more soluble than gypsum is normally less than .2 percent and is less than 4 percent in any horizon as thick as 6 inches. The soil is 90 to 100 percent base saturated. The control section is typically sandy loam but clay ranges from 5 to 18 percent, silt from 5 to 35 percent, and sand from 52 to 82 percent with more than 35 percent fine or coarser sand. Content of coarse fragments is typically less than 5 percent and ranges from 0 to 15 percent. These soils have fluctuating water tables and are saturated at some season of the year and moist in some part of the moisture control section most of the time. Mean annual soil temperature ranges from 47 to 58 degrees F and mean summer soil temperature ranges from 60 to 74 degrees F.
The A1 horizon has hue of 2.5Y or 10YR, value of 4 or 5 dry and 2 or 3 moist, and chroma of 1 or 2. The lower part typically has common medium distinct mottling, but mottles are large or predominant in some pedons. This horizon is neutral to mildly alkaline (pH 6.8 to 7.4). It usually has fine granular or crumb structure but has weak subangular blocky structure in some pedons. This horizon is soft to slightly hard.
The B2g horizon has hue of 2.5Y or 10YR value of 5 or 6 dry and 4 or 5 moist, and chroma of 1 or 2. It typically has large prominent mottles throughout, but in some pedons the mottling is common or distinct. This horizon is neutral to mildly alkaline (pH 6.8 to pH 7.6). Usually it is massive, but it has weak subangular blocky structure in some pedons.
COMPETING SERIES: These are the Massack, Gannett, and Poudre series. Massack soils are medium acid and contain more than 15 percent coarse fragments. Gannett soils have a mollic epipedon less than 24 inches thick. Poudre soils are calcareous at or near the surface, and developed in parent material containing much finely divided mica.
GEOGRAPHIC SETTING: These soils are on flood plains or low terraces. Slope gradients range from 0 to about 5 percent. The soils formed in noncalcareous, moderately coarse textured parent materials derived from a variety of rocks. At the type location the average annual precipitation is 18 inches, but the soils are subject to restricted drainage and have fluctuating water tables. Mean annual temperature is 48 degrees F, mean summer temperature is 68 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Loveland and Niwot soils. Loveland and Niwot soils have fine-loamy over sandy or sandy- skeletal control sections.
DRAINAGE AND PERMEABILITY: Poorly to somewhat poorly drained; slow runoff; medium to rapid permeability above the water table. These soils have fluctuating water tables that are within 3 feet of the surface during most of the year.
USE AND VEGETATION: These soils are used as native pastureland or as cropland. Principal native vegetation is bluegrass, wheatgrass, junegrass, and water tolerant grasses and sedges.
DISTRIBUTION AND EXTENT: Central Colorado in areas bordering 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: Last updated by the state 8/71.