LOCATION MONTICELLO UTEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Typic Argiustolls
TYPICAL PEDON: Monticello very fine sandy loam, rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 4 inches; reddish brown (5YR 4/3); dark reddish brown (5YR 3/3) moist; very fine sandy loam, weak thick platy structure; slightly hard, friable, slightly sticky, slightly plastic; many fine roots; neutral (pH 7.3); clear wavy boundary. (4 to 6 inches thick)
B--4 to 13 inches; reddish brown (5YR 4/3); dark reddish brown (5YR 3/3) moist; very fine sandy loam, moderate medium subangular blocky structure that parts to moderate fine subangular blocky; slightly hard, friable, slightly sticky, slightly plastic; many fine roots; neutral (pH 7.2); clear irregular boundary. (6 to 10 inches thick)
Bt--13 to 36 inches; reddish brown (5YR 5/4); dark reddish brown (5YR 3/4) loam moist, moderate medium subangular blocky structure; hard, friable, slightly sticky, slightly plastic; few fine roots; thin nearly continuous clay films on faces of peds and as bridges between sand grains; slightly alkaline (pH 7.4); gradual wavy boundary. (15 to 25 inches thick)
Bk--36 to 51 inches; light reddish brown (5YR 6/4); dark reddish brown (5YR 3/4) loam moist, moderate medium subangular blocky structure; very hard, friable, slightly sticky, slightly plastic; few fine lime veins; moderately calcareous, moderately alkaline (pH 7.9); gradual smooth boundary. (12 to 16 inches thick)
Ck--51 to 60 inches; reddish brown (5YR 5/4); dark reddish brown (5YR 3/4) loam moist, massive; very hard, friable, slightly sticky, slightly plastic; many thin lime coatings and veins; strongly calcareous, moderately alkaline (pH 8.4).
TYPE LOCATION: San Juan County, Utah; 3 miles east of Monticello School; about 550 feet west and 1,800 feet south of the NE corner of Section 33, T. 33 S., R. 24 E.
RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon: 10 to 16 inches
Solum thickness: 37 to 57 inches
Depth of leaching of carbonates: 13 to 36 inches
Thickness of the eolian mantle: 3 1/2 to 5 feet, and it is underlain by medium textured soil materials that are gravelly in some places
Mean annual soil temperature: 47 to 50 degrees F.
Soil moisture: Typic ustic moisture regime.
A horizon
Value: 4 or 5 dry
Chroma: 2 or 3
Texture: dominantly very fine sandy loam but ranges to loam that is more than 35 percent very fine sand.
Bt horizon
Value: 3 or 4 moist, 4 or 5 dry
Chroma: 4 or 5
Texture: loam, very fine sandy loam or sandy clay loam, with 18 to 25 percent clay and less than 15 percent coarser than very fine sand.
C horizon
Value: 3 to 5 moist, 5 or 6 dry
Chroma: 4 or 5
Texture: loam or very fine sandy loam
Calcium carbonate: slightly or moderately calcareous
Reaction: slightly or moderately alkaline.
COMPETING SERIES: These are the Agar (SD), Eakin (SD), Failo (SD), Highmore (SD), Holdrege (NE), Northdale (UT) and Paka( NE) series. Agar, Eakin, Highmore, and Holdrege soils have hue of 10YR or yellower. Agar and Northdale soils have strong accumulation of carbonates within a depth of 40 inches. Eakin soils have mottles at a depth of 19 to 30 inches. Northdale soils are less than 40 inches deep to bedrock. Paka soils have hue of 7.5YR or yellower and have silty clay loam or silt loam argillic horizons and a paralithic contact at 48 inches. In addition Agar, Eakin, Fairlo, Highmore, Holdredge and Paka soils are in LRR-G and are moist in May and June.
GEOGRAPHIC SETTING: Monticello soils are on undulating to rolling uplands at elevations of 5,800 to 7,500 feet. Slopes are 0 to 10 percent. These soils formed in eolian deposits derived mainly from sandstone. The mean annual precipitation is 14 to 18 inches. The frost-free season is 120 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Northdale soils and the Abajo, Ackmen and Vega soils. Abajo soils average more than 35 percent clay in the particle size control section. Ackmen soils lack an argillic horizon, and Vega soils have a mollic epipedon more than 20 inches and lack an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability.
USE AND VEGETATION: Used mainly for nonirrigated crops of pinto beans and wheat. Some are used for irrigated pasture and alfalfa. The native vegetation is dominantly western wheatgrass, Junegrass, Indian ricegrass, oakbrush, bitterbrush, big sagebrush, pinyon and juniper.
DISTRIBUTION AND EXTENT: Southeastern Utah and southwestern Colorado. These soils are moderately extensive. MLRAs 39 & 48A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: San Juan County (San Juan Area), Utah, 1952.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from 0 to 13 inches (A & B horizon)
Argillic horizon - the zone from 13 to 36 inches (Bt horizon)
Classified according to Keys to Soil Taxonomy Tenth Edition, 2006.
The original type location of the Monticello series was changed because it was in a frigid area. Most of Monticello soils are mesic temperature regime. A new series was set up for the frigid soil.