LOCATION YENLO CO+UTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Ustic Haplargids
TYPICAL PEDON: Yenlo sandy loam, rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 3 inches; light brownish gray (10YR 6/2) sandy loam, dark grayish brown (10YR 4/2) moist; moderate fine granular structure; loose, very friable, nonsticky and nonplastic; neutral (pH 7.2); clear smooth boundary. (2 to 6 inches thick)
Bt1--3 to 7 inches; grayish brown (10YR 5/2) sandy clay loam, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure parting to moderate medium granular; hard, friable, slightly sticky, common distinct clay films on faces of peds; slightly alkaline (pH 7.4); clear smooth boundary. (3 to 5 inches thick)
Bt2--7 to 13 inches; brown (10YR 5/3) sandy clay loam, dark brown (10YR 4/3) moist; weak medium subangular blocky structure parting to moderate fine granular; hard, friable, slightly sticky and slightly plastic; common distinct clay films on faces of peds; slightly alkaline (pH 7.4); clear smooth boundary. (6 to 12 inches thick)
BC--13 to 19 inches; pale brown (10YR 6/3) sandy loam, grayish brown (10YR 5/2) moist; weak coarse subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; slightly alkaline (pH 7.6); clear smooth boundary. (4 to 7 inches thick)
C1--19 to 28 inches; pale brown (10YR 6/3) sandy loam, grayish brown (10YR 5/2) moist; massive; slightly hard, very friable, nonsticky and nonplastic; strongly effervescent; slightly alkaline (pH 7.8); gradual smooth boundary. (4 to 14 inches thick)
C2--28 to 44 inches; pale brown (10YR 6/3) sandy loam, grayish brown (10YR 5/2) moist; massive; slightly hard, very friable, nonsticky and nonplastic; slightly effervescent; moderately alkaline (pH 8.0); gradual smooth boundary. (3 to 14 inches thick)
Ck--44 to 60 inches; light brownish gray (10YR 6/2) sandy clay loam, grayish brown (10YR 5/2) moist; massive; slightly hard, very friable, nonsticky; strongly effervescent; common irregular masses of calcium carbonate visible; moderately alkaline (pH 8.2)
TYPE LOCATION: La Plata County, Colorado; approximately 3,600 feet south and 2,400 feet west of the northeast corner of Section 22, T. 32 N., R. 10 W. U.S.G.S. Long Mountain quad.; Lat. 37 degrees, 52 minutes, 32 seconds N., and Long. 107 degrees, 55 minutes, 10 seconds W.
RANGE IN CHARACTERISTICS: Mean annual soil temperature is 47 to 52 degrees F. Depth to calcareous material ranges from 10 to 24 inches. Thickness of the solum to the base of the BC ranges from 15 to 30 inches. Organic carbon in the upper 15 inches averages about 0.7 to 0.8 percent, and ranges from 0.3 to 1.2 percent. 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. 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.
The A horizon has hue of 2.5Y or 10YR, value of 5 or 6, 3 through 5 moist, and chroma of 1.5 through 4. It is neutral or slightly alkaline.
The Bt horizon has hue of 2.5Y or 10YR, value of 5 through 7, 4 or 5 moist, and chroma of 2 through 4. It is typically sandy clay loam or clay loam, but contains 20 to 30 percent clay, 5 through 35 percent silt, 40 to 75 percent sand, and more than 35 percent fine sand or coarser. Rock fragments range from 0 to 15 percent and are dominantly of gravel size. This horizon is neutral or slightly alkaline and has exchange capacity of 12 to 20 milli equivalents per 100 grams of soil.
The C and Ck horizons have hue of 10YR or 2.5Y. Reaction is slightly alkaline through strongly alkaline. Typically there is about 12 percent calcium carbonate equivalent in the strongest part and ranges from 8 to 20 percent. If any horizon contains over 15 percent calcium carbonate equivalent, it is below 40 inches.
COMPETING SERIES: These are the Balon (AZ), Bowbac (WY), Buckle (NM), Cambria (WY), Cerrillos (NM), Clovis (NM), Cushman (WY), Decolney (WY), Fattig (MT), Fernando (NM), Flaco (NM), Forkwood (WY), Gaddes (AZ), Gapbutte (AZ), Hagerman (NM), Harbord (CO), Los Alamos (NM), Maysdorf (WY), Millett (AZ), Oelop (NM), Olney (CO), Palacid (NM), Penistaja (NM), Pokeman (WY), Potts (WY), Progresso (CO), Pugsley (WY), Quagwa (AZ), Redpen (NM), Scholle (NM), Seipats (WY), Spangler (WY), Spenlo (UT), Sundance (CO), Tapia (NM), Teckla (WY), Threetop (WY), Toluca (MT), and Tuweep (AZ) series.
Balon, Decolney, and Spenlo soils lack free carbonates within depths of 40 inches. Bowbac, Cushman, Fattig, Flaco, Gaddes, Gapbutte, Hagerman, Pokeman, Progresso, Pugsley, Spangler, and Threetop soils have bedrock at depths of 20 to 40 inches. Buckle soils have sola over 40 inches thick. Cerrillos, Clovis, Scholle, Tapia, Toluca, and Tuweep soils have a calcic horizon. Cambric soils are dry in all parts of the moisture control section for at least 60 consecutive days and at least 90 cumulative days from July 15 to October 25. Fernando soils have 50 to 80 percent silt in the solum. Harbord and Potts soils have less than 35 percent fine and coarser sand in the control section. Forkwood soils are dry in all parts of the moisture control section for 60 consecutive days or more from July 15 to October 25. Los Alamos soils have significant amounts of pumice and ash in the control section. Maysdorf and Penistaja soils typically have hue of 5YR or redder in the upper part of the B2t horizon. Millett soils typically contain more than 15 percent gravel in the control section and have hue redder than 10YR in the C horizon. Olney soils have a mean annual soil temperature greater than 52 degrees F., and are in a climatic setting that receives 3/4 of their precipitation between April and September and have a PE Index of about 20. Oelop soils have a C horizon with hues redder than 7.5YR. Palacid soils have less than 35 percent fine sand or coarser. Quagwa soils have mean annual soil temperature of 54 to 57 degrees F. Redpen soils have hue of 5YR or redder. Selpats soils have a skeletal lithologic discontinuity at 15 to 39 inches. Sundance soils have lithic discontinuities formed from eolian sands on top of loess and the argillic horizon formed in part, in both materials. Teckla soils have fragmental discontinuity below the Bt with over 35 percent rock fragments.
GEOGRAPHIC SETTING: Yenlo soils are in upland valleys. Slopes range from 1 to 12 percent. The soils formed in alluvium from sandstone and shale. Elevation ranges from 6,000 to 7,300 feet. Mean annual temperature ranges from 45 to 50 degrees F., and mean summer temperature ranges from 60 to 66 degrees F. Mean annual precipitation ranges from 12 to 15 inches and is fairly evenly distributed throughout the year with about half the precipitation falling between April and September. May and June are the driest months. PE Index is about 41 at the type location and ranges from 25 to 50 for the series.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Florita, Dulce, Picante, Travessilla, and competing Buckle soils. The Florita soils lack argillic horizons. The Dulce, Picante and Travessilla series are shallow soils.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderate to moderately slow permeability.
USE AND VEGETATION: These soils are used mainly for native pastureland. Native vegetation is mainly big sagebrush, rabbitbruxh, western wheatgrass, Indian ricegrass and scattered pinon juniper.
DISTRIBUTION AND EXTENT: Western Colorado and adjoining states. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: La Plata County Area, Colorado, 1982.
REMARKS: This revision updates the classification from an ustollic subgroup to an ustic subgroup to be compatible with the 1994 Amendments to Soil Taxonomy. Diagnostic horizons and features are: an ochric epipedon; an argillic horizon from 3 to 13 inches; a Ck horizon from 44 to 60 inches; 35 percent or more fine sand or coarser throughout the texture control section; a mesic temperature regime. Last updated by the state 3/95.