LOCATION FONDIS COEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aridic Paleustolls
TYPICAL PEDON: Fondis silt loam, grassland. (Colors are for dry soil unless otherwise noted.)
A--0 to 7 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; strong very fine granular structure; soft, very friable; some gray coatings on faces of peds in the lower 1 inch; neutral (pH 7.0); abrupt smooth boundary. (5 to 8 inches thick)
Bt1--7 to 15 inches; brown (10YR 5/3) silty clay, dark brown (10YR 3/3) moist; strong medium and fine prismatic structure parting to strong fine angular blocks; slightly hard, very friable; peds are extremely hard; thin continuous wax-like coatings on faces of peds; wax-like coatings and fillings in root channels and soil pores; neutral (pH 7.2); clear smooth boundary. (7 to 15 inches thick)
Bt2--15 to 23 inches; brown (10YR 5/3) silty clay, dark brown (10YR 4/3) moist; moderate medium prismatic structure parting to strong medium angular and subangular blocks; slightly hard, very friable; peds are extremely hard; thin nearly continuous wax-like coatings on faces of peds and in root channels; calcareous; moderately alkaline (pH 8.0); clear smooth boundary. (0 to 10 inches thick)
2Btkb--23 to 36 inches; pale brown (10YR 6/3) heavy clay loam, dark brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate medium subangular blocks; slightly hard, friable; peds are extremely hard; many thin wax-like patches on faces of peds; wax-like coatings on the inside of root channels; moderate amount of mica; some visible secondary carbonate accumulation as nodules and seams between peds; ped interiors are noncalcareous, the mixed soil mass is calcareous; moderately alkaline (pH 8.2); gradual wavy boundary. (10 to 15 inches thick)
2Bkb--36 to 50 inches; pale brown (10YR 6/3) clay loam, dark yellowish brown (10YR 4/4) moist; weak coarse prismatic structure parting to moderate medium subangular blocks; hard, friable; peds are very hard; thin wax-like patches on faces of peds and in root channels; moderate amounts of mica; about 5 percent fine and very fine angular granite pebbles; visible secondary carbonate as concretions and in thin seams and streaks on faces of peds and throughout the soil mass; calcareous; moderately alkaline (pH 8.2); gradual wavy boundary. (10 to 15 inches thick)
2Ck--50 to 70 inches; light yellowish brown (10YR 6/4) light clay loam, dark yellowish brown (10YR 4/4) moist; massive; very hard, friable; moderate amounts of mica; 5 to 10 percent fine and very fine angular granite pebbles; visible secondary carbonate as concretions and in thin seams and streaks; calcareous; moderately alkaline (pH 8.2).
TYPE LOCATION: Arapahoe County, Colorado; approximately 1,000 feet north and 100 feet east of the southwest corner of Sec. 13, T. 5 S., R. 67 W.
RANGE IN CHARACTERISTICS: Thin E horizons occur in some pedons. The mollic epipedon is 7 to 19 inches thick. Content of organic carbon normally ranges from .7 to 3 percent and decreases uniformly with depth. The soils are 80 to 100 percent base saturated. Cation exchange capacity ranges from 70 to 90 milliequivalents per 100 grams of clay. Mean annual soil temperature ranges from 47 to 58 degrees F. and mean summer soil temperature ranges from 59 to 79 degrees F. Length of time the soil temperature at a depth of 20 inches exceeds 41 degrees F. normally ranges from about 230 to 305 days. Length of time (cumulative) that the soil is moist in some part of the moisture control section while the soil temperature at a depth of 20 inches is above 41 degrees F. normally ranges from 56 to 152 days but in most years it is not less than one-fourth or more than one-half of the time that the soil temperature is above 41 degrees F.
The A horizon has hue of 5Y through 7.5YR, value of 4 or 5, 2 or 3 moist, and chroma of 2 or 3. It usually has granular or crumb primary structure but has subangular blocky structure in some pedons. This horizon is soft to slightly hard. It is slightly acid to mildly alkaline.
The Bt1 and Bt2 horizons have hue of 5Y through 7.5YR, value of 4 through 7, 2 through 6 moist, and chroma of 2 through 6. They are typically silty clay, with 35 to 50 percent clay, 20 to 50 percent silt and 5 to 40 percent sand, with less than 15 percent fine or coarser sand. These horizons usually have prismatic primary structure, but have angular blocky structure in some pedons. They are slightly acid to moderately alkaline, becoming more alkaline with depth.
The 2Bt horizon has the same range in color as the Bt horizon. It is heavy clay loam or clay with more than 15 percent fine or coarser sand, much of which is medium or coarse angular granitic sand. This horizon is mildly alkaline to strongly alkaline
and has visible secondary calcium carbonate in structural cracks in the lower part, although interiors of peds are noncalcareous.
The C horizon has hue of 5Y through 7.5YR. It is a loam or clay loam with less than 35 percent clay. This horizon is moderately alkaline to strongly alkaline and has 4 to 14 percent calcium carbonate equivalent of the fine earth fraction.
COMPETING SERIES: These are the Iliff, Platner, and Weld series. Iliff soils have a lithic contact at depths of less than 40 inches. Platner soils have sola 15 to 40 inches thick and have more than 15 percent fine sand or coarser in the upper part of the Bt horizon. Weld soils lack a lithologic discontinuity within the solum, and have sola 15 to 40 inches thick.
GEOGRAPHIC SETTING: Fondis soils are on tablelands or uplands. Slopes typically range from 0 to about 6 or more percent. The soils formed in thin eolian materials 1 to 2 feet in thickness overlying coarser textured outwash materials derived from arkose deposits of the Denver and Arapahoe or similar formations. At the type location the average annual precipitation is 14 inches with peak periods of precipitation occurring in the spring and early summer months. Mean annual temperature is 47 degrees F., mean summer temperature is 69 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Buick and the competing Weld soils. Buick soils have ochric epipedons and are coarser textured.
DRAINAGE AND PERMEABILITY: Well-drained; slow to medium runoff; slow to moderately slow permeability.
USE AND VEGETATION: They are used as native pastureland or for dry or irrigated cropland. Native vegetation includes short and tall grasses and shrubs.
DISTRIBUTION AND EXTENT: East-central Colorado. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Arapahoe County, Colorado, 1972.