LOCATION SIMPATICO COEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Pachic Argiustolls
TYPICAL PEDON: Simpatico loam - irrigated cropland. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 6 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; weak coarse platy structure parting to moderate medium granules; soft, very friable, slightly sticky and slightly plastic; slightly alkaline (pH 7.4); clear smooth boundary. (2 to 7 inches thick)
AB--6 to 12 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 granules; soft, very friable, slightly sticky and slightly plastic; neutral (pH 7.0); gradual smooth boundary. (2 to 7 inches thick)
Bt1--12 to 24 inches; brown (7.5YR 4/2) silty clay loam, dark brown (7.5YR 3/2) moist; weak moderate medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many prominent clay films on faces of peds and in pores; slightly alkaline (pH 7.4); clear smooth boundary (8 to 20 inches thick)
Bt2--24 to 35 inches; brown (7.5YR 5/2) silty clay loam, dark brown (7.5YR 3/2) moist; moderate medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common prominent clay films on faces of peds; slightly alkaline (pH 7.4); abrupt irregular boundary. (6 to 11 inches thick)
BC--35 to 45 inches; reddish brown (5YR 5/4) silty clay loam, reddish brown (5YR 4/3) moist; weak medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; slightly alkaline (pH 7.4); abrupt irregular boundary. (6 to 11 inches thick)
2C--45 to 60 inches; light brown (7.5YR 6/4) very cobbly loam, brown (7.5YR 5/4) moist; massive; slightly hard, friable, slightly sticky, slightly plastic; 35 percent cobble, 10 percent gravel; slightly effervescent, moderately alkaline (pH 8.0).
TYPE LOCATION: La Plata County, Colorado; about 2,560 feet south and 1,000 feet east of the northwest corner of Sec. 12, T. 34 N., R. 9 W. U.S.G.S. Loma Linda quad.; Lat. 37 degrees, 12 minutes, 21 seconds N., and Long. 107 degrees, 46 minutes, 57 seconds W.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 47 to 53 degrees F. Thickness of the mollic epipedon is 20 to 40 inches and day include all or part of the argillic horizon. Depth to uniformly calcareous material ranges between 40 to 60 inches. Rock fragments in the A and Bt horizons range from 0 to 10 percent but are typically less than 5 percent. Depth to contrasting 2C material ranges from 40 to 60 inches or more. 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.
The A horizon has hue of 7.5YR or 10YR, value of 3 through 5, 2 or 3 moist, and chroma of 1 or 3. Reaction is neutral or slightly alkaline.
The Bt horizon has hue of 5YR or 7.5YR, value of 3 through 5, 2 through 4 moist, and chroma of 2 through 4. It is typically silty clay loam or clay loam but clay content ranges from 27 to 35 percent, silt from 35 to 70 percent and sand from 5 to 35 percent with less than 15 percent being fine sand or coarser. It is neutral or slightly alkaline.
The 2C horizon has hue of 5YR through 10YR. It is very cobbly loam or loam. Glacial outwash or sand and gravel are at depths between 40 to 60 inches or more in some pedons. Reaction is slightly alkaline or moderately alkaline.
COMPETING SERIES: These are the Goshen (NE), Hall (NE), Johnstown (NE), Kinsell, Kuma (CO), Lazarus, Mobridge (SD), and Zepol series. Goshen, Hall, Johnstown, Kuma, and Mobridge soils are moist in some parts of the moisture control section from May 15 to July 15 and are in a climatic setting that receives over 3/4 of their precipitation between April and September. In addition, Kuma soils have polygenetic profiles and Goshen, Hall and Mobridge soils have hues of 10YR in the Bt horizon. Also, Johnstown soils have hue of 10YR in the argillic horizon, and have buried horizons below depths of 14 to 35 inches. Kinsell, Lazarus, and Zepol soils have an aridic moisture regime.
GEOGRAPHIC SETTING: Simpatico soils are in upland swales of mesa tops, in drainageways, and on fans. Elevations are 6,000 to 7,400 feet. Slopes range from 0 to 6 percent. The soils formed in alluvium from nearby loess deposits. Average annual temperature ranges from 45 to 50 degrees F., and mean summer temperature ranges from 60 to 68 degrees F. Mean annual precipitation ranges from 15 to 18 inches and is distributed fairly evenly throughout the year with about half the precipitation falling between April and September. May and June are the driest months. PE Index is about 50 at the type location and ranges from 25 to 60 for the series.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Falfa, Lazear, Pulpit, Vosburg, and Witt soils. Falfa soils have more clay in the argillic horizons. Lazear soils are shallow and Pulpit soils have sandstone bedrock at depths of 20 to 40 inches. Vosburg soils have fine-loamy particle-size control sections. Witt soils have light colored A horizons.
DRAINAGE AND PERMEABILITY: Well drained; medium to low runoff; moderate slow permeability. Many areas are subject to flooding from snow melt and high intensity rain storms.
USE AND VEGETATION: These soils are used for irrigated and dry cropland. Crops grown are alfalfa, pasture, small grains, and beans. Native vegetation is Indian ricegrass, western wheatgrass, blue grama, junegrass, needleandthread and big sagebrush.
DISTRIBUTION AND EXTENT: Simpatico soils occur in western Colorado and possibly adjacent parts of Utah. The series is of small extent. MLRA 36.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: La Plata County Area, Colorado, July 1982.
REMARKS: Diagnostic horizons and features recognized are:
Mollic epipedon (Pachic feature): from 0 to 35 inches (Ap, AB, Bt1, Bt2 horizons).
Argillic horizon: from 12 to 35 inches (Bt1, Bt2 horizons)
Taxonomic version: classified according to Ninth Edition, 2003