LOCATION NELMAN CO+UTEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, calcareous, mesic Ustic Torriorthents
TYPICAL PEDON: Nelman fine sandy loam - grassland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 6 inches; pinkish gray (7.5YR 6/2) fine sandy loam, dark brown (7.5YR 4/2) moist; moderate fine granular structure; soft, very friable; 5 percent sandstone fragments; calcareous; moderately alkaline (pH 8.2); clear smooth boundary. (4 to 8 inches thick)
AC--6 to 10 inches; light brown (7.5YR 6/3) fine sandy loam, dark brown (7.5YR 4/3) moist; weak medium subangular blocky structure that parts to moderate fine granules; slightly hard, very friable; 10 percent sandstone fragments; calcareous; moderately alkaline (pH 8.2); gradual wavy boundary. (3 to 6 inches thick)
C--10 to 26 inches; pink (7.5YR 7/4) fine sandy loam, light brown (7.5YR 6/4) moist; massive; slightly hard, very friable; 10 percent sandstone fragments; few soft concretions of secondary carbonates; calcareous; moderately alkaline (pH 8.2); abrupt wavy boundary. (6 to 33 inches thick)
R--26 to 28 inches; hard calcareous sandstone.
TYPE LOCATION: Mesa County, Colorado; SE1/4 Sec. 8, T. 3 S., R. 2 E.
RANGE IN CHARACTERISTICS: Depth to the lithic contact ranges from 20 to 40 inches. Organic carbon of the surface 15 inches averages approximately .5 percent. Sand/clay ratio ranges from 3 to 10. The control section is sandy loam or fine sandy loam with 8 to 18 percent clay. The C horizon generally contains some visible calcium carbonate accumulation but such accumulation is discontinuous and variable among pedons and is not considered to be definitive of the series. The mean annual soil temperature ranges from 47 to 58 degrees F., and the mean summer soil temperature ranges from 60 to 78 degrees F. These soils are usually moist in some part between depths of 8 to 24 inches or to bedrock if shallower for approximately 1/4 to 1/2 of the time the soil temperature is above 41 degrees F. and are moist in all parts between depths of 8 and 24 inches or to bedrock if shallower for less than 60 cumulative days during the 120 days following the winter solstice.
The A1 horizon has hue of 10YR or 7.5YR, value of 5 through 7 dry, 3 through 5 moist, and chroma of 2 through 4. When the surface horizon is as dark as 5 dry or 3 moist it is too thin or contains too little organic carbon to qualify as a mollic epipedon. This horizon is mildly to strongly alkaline (pH 7.8 to 8.6). It is soft or slightly hard.
The C horizon has hue of 2.5Y to 7.5YR. It is moderately or strongly alkaline (pH 8.0 to 9.0) and has about 1 to 6 percent calcium carbonate equivalents.
COMPETING SERIES: These are the Nelson, Otero, Pedrick, and Shavano series. Nelson soils have a paralithic contact at depths of 20 to 40 inches. Otero and Pedrick soils have bedrock at depths greater than 40 inches. Shavano soils have more than 18 percent clay in the control section.
GEOGRAPHIC SETTING: Nelman soils are on benches, canyon side slopes, upland hills, and ridges. Slope gradients range from 2 to 59 percent. The soils formed in moderately thick, calcareous, moderately coarse textured sediments weathered from sandstone bedrock. At the type location average annual precipitation is 12 inches with peak periods of precipitation occurring during the spring and early summer. Average annual temperature is 40 degrees F., and the average summer temperature is 63 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Otero soils and the Travessilla soils. Travessilla soils have a lithic contact at depths of 10 to 20 inches. Nelman series is the intermediate member of the Travessilla, Nelman, and Otero toposequence.
DRAINAGE AND PERMEABILITY: Well to somewhat excessively drained; slow runoff; rapid permeability above the bedrock.
USE AND VEGETATION: These soils are used as native pastureland and occasionally as dry cropland or irrigated farm land. Native vegetation is shadscale, cactus, snakeweed, galleta grass, Indian ricegrass, and blue grama in the more moist ends of the series range.
DISTRIBUTION AND EXTENT: The western slope of Colorado. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Mesa County (Lower Colorado Area), Colorado, 1970.
REMARKS: Last updated by the state 4/73.
The superactive cation exchange activity class was added in 03/2003 to the taxonomic classification by the National Soil Survey Center on request of the Lakewood MLRA office, without review of the soil series property data. The remainder of this document has not been updated.