LOCATION RAGO COEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Pachic Argiustolls
TYPICAL PEDON: Rago silt loam in a cultivated area. (Colors are for dry soil unless noted.)
Ap--0 to 10 centimeters (0 to 4 inches); grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure parting to moderate medium granular; slightly hard, very friable, slightly sticky, slightly plastic; neutral (pH 7.0); clear smooth boundary. (4 to 8 inches thick)
BA--10 to 23 centimeters (4 to 9 inches); grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; few faint clay films on faces of peds and in tubular pores; neutral (pH 7.0); clear smooth boundary. (0 to 20 centimeters (0 to 8 inches) thick)
Bt--23 to 46 centimeters (9 to 18 inches); brown (10YR 5/3) silty clay loam, dark brown (10YR 3/3) moist; moderate medium and fine prismatic structure parting to medium subangular blocky; slightly hard, very friable, sticky, plastic; common distinct clay films on faces of peds and in tubular pores; slightly alkaline; (pH 7.4) abrupt smooth boundary. (20 to 51 centimeters (8 to 20 inches) thick)
Btkb1--46 to 76 centimeters (18 to 30 inches); dark gray (10YR 4/1) silty clay, black (10YR 2/1) moist; moderate medium and fine prismatic structure parting to strong angular blocky; slight hard, very friable, sticky, plastic; common distinct clay films on the faces of peds and in tubular pores; accumulation of secondary calcium carbonate on faces of peds but the interiors of peds are mostly noncalcareous; slightly effervescent; the crushed soil mass is moderately alkaline (pH 8.0); gradual wavy boundary. (20 to 51 centimeters (8 to 20 inches) thick)
Btkb2--76 to 104 centimeters (30 to 41 inches); light brownish gray (10YR 6/2) silty clay loam, grayish brown (10YR 5/2) moist; weak medium prismatic structure parting to medium and fine subangular blocky; slightly hard, very friable, slightly sticky, slightly plastic; few faint clay films on faces of peds and in tubular pores; thin seams of lime; violently effervescent; moderately alkaline (pH 8.2); gradual smooth boundary. (15 to 36 centimeters (6 to 14 inches) thick)
Bkb--104 to 152 centimeters (41 to 60 inches); pale yellow (2.5Y 7/3) silt loam, light olive brown (2.5Y 5/3) moist; massive; hard, very friable, slightly sticky; slightly plastic; soft masses and thin seams of lime; violently effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Washington County, Colorado; 6 kilometers (4 miles) east of Akron; 396 meters (1,300 feet) north and 24 meters (80 feet) west of the southeast corner of Sec. 21, T. 2 N., R. 52 W.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 9 to 12 degrees C. (48 to 54 degrees F.)
Mean summer soil temperature: 20 to 23 degrees C. (68 to 73 degrees F.)
Depth to calcareous material: 25 to 102 centimeters (10 to 40 inches)
Mollic epipedon: 51 to 127 centimeters (20 to 50 inches) thick
Depth of the argillic horizon base: 61 to 152 centimeters (24 to 60 inches)
Depth to continuous subhorizons of visible secondary calcium carbonate and/or sulfate: 51 to 102 centimeters (20 to 40 inches)
Rock fragments: 0 to 5 percent by volume mainly fine pebbles in a major part of the solum and C horizon above a depth of 127 centimeters (50 inches)
Moisture control section: dry in some or all parts for 90 or more cumulative days when the soil temperature at 51 centimeters (20 inches) is greater than 5 degrees C. (41 degrees F.)
Precipitation peak: May and June
Polygenetic solums: younger soil is superimposed on and merges with a paleosol so that either or both of the following conditions occur:
(1) Some subhorizon of the lower solum is at least 1/2 a unit of value darker or 1/2 unit of chroma grayer or 1/4 unit of hue yellowier than the overlying horizons accompanied by horizons of clay accumulation and visible secondary calcium carbonate accumulations predominantly on the surfaces of the peds or in the structural cracks between peds.
(2) Some profiles have solums more than 40 inches thick to the base of the argillic horizon accompanied by horizons of clay accumulation in the lower solum and also having visible accumulation of secondary calcium carbonate on the faces of the peds or in structural cracks between peds and the interiors of at least some of the peds are noncalcareous.
A horizon:
Hue: 2.5Y to 7.5YR
Value: 4 or 5, 2 or 3 moist
Chroma: 1 to 3
Texture: silt loam, clay loam, loam
Reaction: neutral or slightly alkaline
Bt horizon:
Hue: 2.5Y to 7.5YR
Value: 4 or 5, 2 or 3 moist
Chroma: 1 to 3
Texture: silty clay loam, clay loam, silty clay or clay
Clay content: 35 to 50 percent
Silt content: 20 to 55 percent
Sand content: 5 to 40 percent, less than 15 percent being fine or coarser sand
Reaction: neutral or slightly alkaline
Btk or Btkb horizon:
Hue: 2.5Y to 7.5YR
Value: 4 to 6, 2 to 5 moist
Chroma: 1 to 3
Texture: silty clay loam, clay loam, silty clay or clay
Percentages of sand, silt, and clay: same as Bt horizon except in some pedons thin subhorizons upper part of the Paleosol have less than 35 percent clay
Reaction: slightly to strongly alkaline
Calcium carbonate: 1 to about 10 percent
Bkb or C horizon:
Hue: 2.5Y to 7.5YR
Texture: silt loam, loam, fine sandy loam, sandy loam, clay loam or silty clay loam:
Clay content: 10 to 35 percent
Silt content: 10 to 70 percent
Sand content: 10 to 80 percent
Calcium carbonate equivalent: 3 to 15 percent
COMPETING SERIES: These are the
Crete,
Detroit,
Lane,
Onita,
Pinespring,
Smolan and
Sponiker series.
Crete and Detroit soil are leached for greater depth, have monogenetic solums, and are moist more than 1/2 the time soil temperature is 5 degrees C. (41 degrees F.), or higher.
Lane and Onita soils have monogenetic profiles.
Smolan soils lack a buried horizon.
The Pinespring and Sponiker soils are driest in the months of
May and June.
GEOGRAPHIC SETTING:
Landform: concave upland flats, drainageways, floodplains and depressions
Slopes: 0 to 6 percent
Parent Material: eolian materials of two ages with a Paleosol marking the point of contact and alluvium
Mean annual precipitation: 28 to 43 centimeters (11 to 17 inches)
Peak periods of precipitation: spring and early summer months
Mean annual temperature: 8 to 11 degrees C. (47 to 52 degrees F.)
Mean summer temperature: 20 to 22 degrees C. (68 to 71 degrees F.)
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Kuma and
Keith soils.
Kuma soils have argillic horizons with less than 35 percent clay.
Keith soils have dark surface layers less than 51 centimeters (20 inches) thick.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage: well to moderately well drained
Runoff: very low to low
Saturated Hydraulic Conductivity: moderately low
USE AND VEGETATION: Used as grazing land or as irrigated or dry cropland.
Native vegetation is blue grama, cactus, and buffalograss.
DISTRIBUTION AND EXTENT: Eastern Colorado in MLRA's 67 and 69. The series is of large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Akron Area, Washington County, Colorado, 1947.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon (Pachic): 0 to 76 centimeters (0 to 30 inches) (Ap, BA, Bt, and Btkb1 horizons)
Polygenetic Bt: 23 to 104 centimeters (9 to 41 inches) (Bt and Btkb horizons)
Soil was last updated by the state 3/94.
Modified format by LRM in 3/2006 to include metric conversion and change permeability to saturated hydraulic conductivity.