LOCATION COLOMBO CO+SD WYEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, mesic Torrifluventic
Haplustolls
TYPICAL PEDON: Colombo clay loam - irrigated cropland. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 14 inches; dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; weak medium granular structure; slightly hard, friable, slightly effervescent; moderately alkaline; clear smooth boundary. (10 to 20 inches thick)
C1--14 to 21 inches; pale brown (10YR 6/3) stratified clay loam and loam, brown (10YR$ 5/3) moist; weak coarse subangular blocky structure grading to massive; slightly hard, friable; strongly effervescent; moderately alkaline; gradual smooth boundary. (4 to 12 inches thick)
C2--21 to 60 inches; very pale brown (10YR 7/3) loam stratified with thin lenses of fine sandy loam, fine sand, medium sand and clay loam, pale brown (10YR 6/3) moist; massive; slightly hard, friable; strongly effervescent; moderately alkaline.
TYPE LOCATION: Weld County, Colorado; 2,350 feet north, 2,000 feet east of the SW corner of Sec. 4, T. 5 N., R. 64 W.
RANGE IN CHARACTERISTICS: Usually these soils are calcareous throughout, but may be leached to a depth of 10 to 18 inches. The control section lacks continuous subhorizons of secondary calcium carbonate and/or sulfate but some pedons have some visible accumulation. The mollic epipedon ranges from 8 to 16 inches thick. The 10- to 40- inch control section is usually loam or light clay loam stratified with thin lenses of sand and clay loam. It averages 18 to 35 percent clay, 15 to 50 percent silt, and 20 to 60 percent sand. Rock fragments range from 0 to 15 percent by volume and are mainly 1/2 to 10 inches in diameter.
The A horizon has hue of 2.5YR through 7.5YR, value of 4 or 5 dry, 2 or 3 moist, and chroma of 1 through 3. It is mildly or moderately alkaline.
The C horizon has hue of 2.5Y through 7.5YR. It is moderately or strongly alkaline.
COMPETING SERIES: These are the Haverson, Mill, and Uncom series. Haverson soils lack a mollic epipedon. Mill soils are coarse-loamy and have hue of 5YR or redder in a majority of subhorizons. Uncom soils are coarse-loamy and have the lower part of their moisture control section moistened by a fluctuating water table or its capillary fringe.
GEOGRAPHIC SETTING: Colombo soils are on flood plains, terraces, and drainageways. Slopes range from 0 to 6 percent. The soils formed in thick, stratified, calcareous, predominantly medium to moderately fine textured, mixed alluvium. At the type location, the mean annual precipitation is about 12 inches with peak periods of precipitation occurring in the spring and early summer. Mean annual temperature is 48 degrees F, mean summer temperature is 70 degrees F. The frost-free season is about 130 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Glenberg soils and the competing Haverson soils. Glenberg soils lack a mollic epipedon.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderate permeability.
USE AND VEGETATION: These soils are used as grazing land, cropland, and native meadow. Native vegetation is sagebrush, blue grama, and native bluegrass.
DISTRIBUTION AND EXTENT: Northeastern and western Colorado. This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Weld County, Colorado, 1976.
REMARKS: Last updated by the state 7/76.