Established Series


The Shalona series consists of very deep, well drained soils that occur on old high terraces and alluvial flats on structural benches. It is formed in mixed alluvium from sandstone and shale. Slopes range from 0 to 8 percent. Mean annual precipitation is about 16 inches and mean annual temperature is about 47 degrees F.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Aridic Argiustolls

TYPICAL PEDON: Shalona loam-rangeland. (Colors are for dry soil unless otherwise noted.)

A1--0 to 2 inches; pinkish gray (7.5YR 6/2) loam, brown (7.5YR 4/2) moist; weak coarse platy structure parting to weak, very fine granular; soft, very friable; neutral (pH 6.8); abrupt smooth boundary (1 to 4 inches thick)

A2--2 to 7 inches; brown (7.5YR 5/2) clay loam, dark brown (7.5YR 3/2) moist; weak, subangular blocky structure parting to moderate, fine granular; slightly hard, friable; slightly sticky; neutral (pH 7.0); clear smooth boundary. (3 to 7 inches thick)

BA--7 to 14 inches; dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist; moderate, fine subangular blocky structure parting to strong, medium granular; slightly hard, friable; sticky; many distinct clay films on faces of peds; neutral (pH 7.0); clear smooth boundary. (4 to 9 inches thick)

Bt--14 to 35 inches; brown (7.5YR 5/2) clay loam, brown (7.5YR 4/2) moist; moderate, medium prismatic structure parting to moderate, medium subangular blocks; very hard, firm, sticky; many prominent clay films on faces of peds; neutral (pH 7.2); gradual smooth boundary. (10 to 25 inches thick)

Btk--35 to 43 inches; brown (7.5YR 5/2) clay loam, brown (7.5YR 4/2) moist; weak, medium subangular blocky structure; hard, firm, sticky; common distinct clay films on faces of peds; slightly effervescent; few thin seams of calcium carbonate visible. slightly alkaline (pH 7.8); gradual smooth boundary. (6 to 11 inches thick)

Ck--43 to 60 inches; pale brown (10YR 6/3) loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, friable; slightly sticky; slightly effervescent; few irregular masses of calcium carbonate visible; moderately alkaline (pH 8.0).

TYPE LOCATION: La Plata County, Colorado; 600 feet west and 350 feet north of the southeast corner of Sec. 24, T. 34., R. 10 W. U.S.G.S. Basin Mountain quad.; Lat. 37 degrees, 10 minutes, 14 seconds N., and Long. 107 degrees, 52 minutes, 41 seconds W.


The moisture control section is dry for 15 consecutive days from May 15 to July 15 when the soil temperature at 20 inches is greater than 41 degrees F. (5 degrees C.). It is not dry in all parts of the moisture control section for at least 45 consecutive days following the summer solstice to October 20, and for at least 90 cumulative days during that period. an aridic ustic moisture regime; and a mesic temperature regime.

Depth to base of Bt horizon ranges from - 20 to 44 inches.

Thickness of mollic epipedon - 8 to 20 inches.

Depth to calcareous material ranges from - 20 to 40 inches.

Rock fragments range from - 0 to 10 percent and are mainly gravel and cobble.

A horizons
Hue: 7.5 YR or 10YR
Value: 4 or 5, 2 or 3 moist,
Chroma: 2 or 3
Other features: Some thin A1 horizons are lighter colored.
Reaction: Neutral or slightly alkaline.

Bt horizon
Hue: 7.5YR or 10YR
Value: 4 to 6, 3 to 5 moist
Chroma: 2 to 4
Texture: clay loam, loam, or silty clay loam
Clay content ranges from 18 to 35 percent, silt from 15 to 55 percent, and sand from 15 to 60 percent with more than 15 and less than 35 percent being fine or coarser sand.
Reaction: Neutral to slightly alkaline.

Ck horizon
Hue: 7.5YR to 2.5Y
Texture: Loam, clay loam, or silt loam and may have lenses of sandy loam.
Reaction: slightly alkaline or moderately alkaline.

COMPETING SERIES: These are Ascalon (CO), Asparas (NM), Belfon (KS), Bresser (CO), Cedak (WY), Critchell (CO), Dagflat (UT), Datil (NM), Featherlegs (WY), Forgan, Harlan (WY), Hemingford (NE), Hiarc (NM), Kirtley (WY), Lavate (UT), Loarc (NM), Moskee (WY), Noden (WY), Recluse (WY), Satanta (KS), Sitcan (T), Sugardee (WY), Wages (CO), and Wolf (WY) series.
Ascalon series has particle-size control sections with 35 percent or more fine or coarser sand.
Asparas and Datil soils have free carbonates above 20 inches.
Belfon soils have buried horizons at depths ranging from 20 to 38 inches.
Bresser, Critchell, Lavate, Loarc, and Noden soils are leached of calcium carbonates to depths greater than 40 inches.
Capulin and Wolf soils have calcic horizons at depths of less than 40 inches.
Cedak, Chacuaco, Dagflat, Hargreave, Hiarc, Kirtly, Rosebud, and Ryegate soils have bedrock at depths less than 40 inches.
Featherlegs soils have very gravelly materials at depths of 30 to 40 inches.
Harlan soils have hues of 5YR or redder in the B and C horizons.
Hemingford soils have soft bedrock at depths of 40 to 60 inches, and are moist in some part of the soil moisture control section from May 15 to July 15.
Moskee soils are moist in all or some part of the moisture control section for more than 40 cumulative days from May 15 to July 15, and they receive two thirds of their precipitation in April, May and early June.
Palmer Canyon soils have loamy-skeletal substratum at depths of 20 to 40 inches.
Recluse soils are dry in the moisture control section for 90 cumulative days from July 15 to October 25.
Sugardee soils have very gravelly loams or very gravelly clay loam C horizons.
Satanta soils have a mean annual soil temperature greater than 54 degrees F. and are in a climatic setting that receives about 3/4 of the precipitation between April and September and has a PE Index of about 29.
Wages and Wolf soils have sola less than 15 inches deep to the base of the argillic horizon.
Sitcan soils control section is moist May and June and moist intermittently July and August.

GEOGRAPHIC SETTING: Shalona soils are on old high river terraces and alluvial flats on structural benches. They are formed in mixed alluvium and residuum from sandstone and shale. Elevation ranges from 5,000 to 7,000 feet. Average annual temperature ranges from 45 to 53 degrees F. Slopes range from 0 to 8 percent. Mean annual precipitation ranges from 13 to 18 inches and is distributed fairly evenly throughout the year. About half the precipitation falls between April and September with May and June being the driest months. The PE Index is 42 at the type location and ranges from 35 to 50 for the series. The frost-free period is 100 to 120 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Mikim and the competing
Harlan soils. The Mikim soils lack a mollic epipedon and are on slightly
steeper slopes.

DRAINAGE AND PERMEABILITY: Well drained; low runoff; moderately slow to moderate permeability.

USE AND VEGETATION: The soil is used primarily for irrigated cropland or pasture and rangeland. Alfalfa, barley, and oats are the main crops. Native vegetation includes western wheatgrass, Indian ricegrass, muttongrass, Junegrass, squirreltail, big sagebrush, pinyon pine, and Rocky Mountain juniper.

DISTRIBUTION AND EXTENT: Shalona soils occur in Southwestern Colorado and are of minor extent.


SERIES ESTABLISHED: La Plata County Area, Colorado, 1981.


Diagnostic horizons and features recognized are:

Mollic epipedon - the zone from 0 to 14 inches;

Argillic horizon - the zone from 7 to 43 inches;

Visible carbonates in the Btk and Ck horizons;

an aridic ustic moisture regime; and a mesic temperature regime.

National Cooperative Soil Survey