LOCATION ILIFF COEstablished Series
The Iliff series consists of moderately deep, well and moderately well drained soils that formed in medium and moderately fine textured loess materials high in carbonates and loess over cemented calcareous sandstone. Iliff soils are on upland plains and have slopes of 0 to 6 percent. The mean annual precipitation is about 41 centimeters (16 inches) and mean annual temperature is about 10 degrees C. (49 degrees F.) at the type location.
TAXONOMIC CLASS: Fine, smectitic, mesic Aridic Paleustolls
TYPICAL PEDON: Iliff loam - grassland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 8 centimeters (0 to 3 inches); grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; slightly hard, friable; neutral; clear smooth boundary. (5 to 15 centimeters (2 to 6 inches) thick)
A2--8 to 15 centimeters (3 to 6 inches); grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; weak coarse subangular blocky structure parting to weak fine granular; slightly hard, friable; neutral; abrupt smooth boundary. (5 to 10 centimeters (2 to 4 inches) thick)
E--15 to 20 centimeters (6 to 8 inches); light brownish gray (10YR 6/2) loam, very dark grayish brown (10YR 3/2) moist; weak coarse subangular blocky structure; slightly hard, friable; neutral; abrupt smooth boundary. (0 to 8 centimeters (0 to 3 inches) thick)
Bt--20 to 38 centimeters (8 to 15 inches); very dark grayish brown (10YR 3/2) silty clay loam, very dark brown (10YR 2/2) moist; strong medium and fine prismatic structure parting to strong medium and fine angular blocks; hard; firm; many continuous distinct clay films; slightly alkaline; clear smooth boundary. (10 to 30 centimeters (4 to 12 inches) thick)
BCk--38 to 56 centimeters (15 to 22 inches); light brownish gray (10YR 6/2) silty clay loam, dark grayish brown (10YR 4/2) moist; moderate medium prismatic structure parting to moderate medium subangular blocks; hard, friable; few patchy distinct clay films; strongly effervescent; moderately alkaline; clear smooth boundary. (10 to 30 centimeters (4 to 12 inches) thick)
Ck--56 to 74 centimeters (22 to 29 inches); light gray (2.5Y 7/2) silt loam, grayish brown (2.5Y 5/2) moist; massive; soft, very friable; violently effervescent; moderately alkaline; smooth boundary. (10 to 41 centimeters (4 to 16 inches) thick)
C--74 to 86 centimeters (29 to 34 inches); light gray (2.5Y 7/2) loam, grayish brown (2.5Y 5/2) moist; massive; soft, very friable; moderately alkaline; gradual smooth boundary. (8 to 30 centimeters (3 to 12 inches) thick)
R--86 centimeters (34 inches); white (10YR 8/1) caliche sandstone of the Ogallala formation.
TYPE LOCATION: Logan County, Colorado; 367 meters (1205 feet) north and 12 meters (40 feet) east of the southwest corner of Sec. 27, T. 7 N., R. 50 W.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 10 to 13 degrees C. (50 to 55 degrees F.)
Solum: 38 to 89 centimeters (15 to 35 inches) thick
Mollic epipedon: 20 to 49 centimeters (8 to 19 inches) thick
Carbonates depths: 36 to 53 centimeters (14 to 21 inches)
Depth to caliche: 76 to 102 centimeters (30 to 40 inches), (range of 51 to 102 centimeters (20 to 40 inches)
A horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5, 2 or 3 moist
Chroma: 1 to 3
Texture: silt loam and loam.
E horizon:
Hue: 7.5YR or 10YR
Value: 6 or 7, 3 to 5 moist
Chroma: 1 or 2 (Some cultivated areas have the A and E horizons mixed.)
Bt horizon:
Hue: 7.5YR to 2.5Y
Value: 3 to 5, 2 to 4 moist
Chroma: 2 or 3
Texture: silty clay loam or clay (35 to 50 percent clay)
(minimum increase of 20 percent clay within 3 inches of the upper boundary)
Bk horizon:
Hue: 7.5YR to 2.5Y
Value: 5 or 6, 4 or 5 moist
Chroma: 2 or 3
Texture: silty clay loam or clay loam (30 to 40 percent clay)
Calcium carbonate: 5 to 15 percent (of the fine earth)
BCk horizon:
Hue: 7.5YR to 2.5Y
Value: 4 to 7, 2 to 6 moist
Chroma: 2 or 3
Texture: silty clay loam or clay loam (30 to 40 percent clay)
C horizon:
Hue: 5Y to 7.5YR
Value: 6 or 7, 5 or 6 moist
Chroma: 2 or 3
Texture: silt loam, loam, and clay loam (20 to 35 percent clay)
COMPETING SERIES: These are the
Dawes,
Fondis,
Jonpol,
Platmak,
Platner and
Platsher series.
Dawes soils have a lithic contact at depths between 100 and 203 centimeters (40 to 80 inches).
Fondis, Platmak, Platner and Platsher soils lack a lithic contact.
Jonpol soils have a paralithic contact at 51 to 100 centimeters (20 to 40 inches).
GEOGRAPHIC SETTING:
Parent material: medium and moderately fine textured loess materials that contain considerable carbonates
Landform: upland plains
Slopes: 0 to 6 percent
Exchangeable sodium: 8 to 15 percent
Underlying caliche: part of the Ogallala sandstone formation that limits root and moisture penetration
Climate: semiarid
Mean annual precipitation: 33 to 43 centimeters (13 to 17 inches)
Mean annual temperature: 8 to 11 degrees C. (47 to 52 degrees F.)
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing
Platner soils as well as
Rosebud and
Weld soils.
Rosebud soils have fine-loamy Bt horizons.
Weld soils lack a lithic contact between 51 to 102 centimeters (20 and 40 inches).
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage: well and moderately well drained
Runoff; low
Saturated Hydraulic Conductivity: moderately low
USE AND VEGETATION: most areas are cultivated
The main crops are wheat, sorghum, and feed crops.
A small percentage remains in range.
Native vegetation is blue grama, buffalo grass, and western wheatgrass.
DISTRIBUTION AND EXTENT: Northeastern Colorado and western Nebraska. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Logan County, Colorado, 1974.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Argillic horizon: 20 to 38 centimeters (8 to 15 inches)
Lithic contact: 86 centimeters (34 inches)
Clay increase: 20% or more within a vertical distance of 7.5 cm or 15% or more within 2.5cm in the fine-earth fraction.
Last updated by the state 3/94
Modified format by LRM in 10/2005 to include metric conversion and change permeability to saturated hydraulic conductivity.