LOCATION ROCKWELL MN+NDEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Typic Calciaquolls
TYPICAL PEDON: Rockwell sandy clay loam with a slightly concave level slope on a lake plain in a pasture. (Colors are for moist soil unless otherwise stated.)
A--0 to 9 inches; black (N 2/0) sandy clay loam; weak very fine subangular blocky structure; very friable; many roots; strong effervescence; slightly alkaline; clear smooth boundary. (7 to 14 inches thick)
Bkg--9 to 19 inches; dark gray (5Y 4/1) and gray (5Y 5/1) fine sandy loam; weak very fine granular structure; very friable; few roots; discontinuous very dark gray (10YR 3/1) layer in lower part; violent effervescence; slightly alkaline; clear wavy boundary. (6 to 20 inches thick)
2Cg1--19 to 27 inches; light olive gray (5Y 6/2) and pale olive (5Y 6/3) fine sand; common medium prominent yellowish brown (10YR 5/6), strong brown (7.5YR 5/8), and brown (7.5YR 4/4) redoximorphic concentrations; single grain; loose; few roots; few thin strata with up to 5 percent gravel; slight effervescence; slightly alkaline; clear smooth boundary. (0 to 14 inches thick)
3Cg2--27 to 60 inches; light olive gray (5Y 6/2) silt loam; many medium prominent yellowish brown (10YR 5/8) and reddish brown (5YR 4/4) redoximorphic concentrations; massive; friable; common layers of very fine sandy loam in upper part and few layers of loam in the lower part; slight effervescence; slightly alkaline.
TYPE LOCATION: Norman County, Minnesota; about 5 miles north of Gary; 530 feet west and 240 feet north of the southeast corner of Sec. 22, T. 146 N., R. 44 W.
RANGE IN CHARACTERISTICS: The mollic epipedon is 7 to 18 inches thick. The depth to the 2C horizon is 20 to 40 inches. The 10- to 40-inch particle size control section averages between 8 and 18 percent clay and typically 30 to 60 percent fine sand and coarser. The average texture is no coarser than sandy loam. Carbonates are in all parts of the A and C horizons. These horizons are slightly alkaline or moderately alkaline. Rock fragments comprise 0 to 8 percent of the volume of the 3C horizon and typically are absent in most of the horizons above the 3C horizon. In a few pedons a thin pebble band is at the contact of the 2C and the 3C horizons.
The A horizon has hue of 10YR to 5Y or is neutral, value of 2 or 3, and chroma of 0 or 1. Texture is sandy loam, fine sandy loam, loam, sandy clay loam, or clay loam. It has slight to violent effervescence. Some pedons have an Ak horizon.
The Bkg horizon has hue of 5Y to 10YR or is neutral, value of 4 to 6, and chroma of 0 to 2. The Bkg horizon has mottles in some pedons, and distinct or prominent mottles are required if the hue is 10YR or if the chroma is 2. Texture is typically sandy loam, fine sandy loam or loam, but ranges to loamy sand, sandy clay loam, or clay loam in some pedons. Effervescence is strong or violent. Irregular shaped masses of the A horizon are in the Bkg horizon of some pedons. These probably resulted from frost action. The calcic horizon has a calcium carbonate equivalent of 15 to 30 percent.
The 2Cg horizon has hue of 2.5Y or 5Y, value of 5 or 6, and a typical chroma of 1 to 3. It has distinct or prominent redoximorphic features in most parts. Texture is sand, fine sand, loamy sand, or loamy fine sand. The average texture between depths of 10 inches and the top of the 3Cg horizon is sandy loam or fine sandy loam.
The 3Cg horizon has hue of 2.5Y or 5Y, value of 5 or 6, and chroma of 1 or 2. Texture is loam, silt loam, sandy loam, fine sandy loam, very fine sandy loam, clay loam, or silty clay loam. Calcium carbonate equivalent is 10 to 25 percent.
COMPETING SERIES: These are the Arveson, Hedman and Percy series. Arveson soils formed in outwash or lacustrine deposits throughout the upper 40 inches and have less than 1 percent rock fragments in the upper 40 inches. Hedman soils formed in till throughout and have more than 1 percent rock fragments throughout. Percy soils have till at depths of less than 20 inches and have a calcium carbonate equivalent of more than 25 percent below the Bk horizon.
GEOGRAPHIC SETTING: These soils are on flats and shallow depressions on lake plains and moraines. Slope gradients are 2 percent or less. The Rockwell soils formed in 20 to 40 inches of calcareous loamy or loamy and sandy lacustrine sediments overlying loamy calcareous till or silty lacustrine sediments of Late Wisconsin age. Mean annual air temperature is 36 to 46 degrees F. Mean annual precipitation is 16 to 26 inches. Frost-free days range from 88 to 150. Elevation above sea level ranges from 785 to 1950 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arveson, Borup, Grimstad and Kratka series. The moderately well and somewhat poorly drained Grimstad and the poorly and very poorly drained Kratka soils have formed in similar materials and are members of a drainage sequence with the Rockwell soils. Grimstad soils are on higher lying terrain, and Kratka soils commonly are in slight depressions and do not have a layer of calcium carbonate accumulation above a depth of 16 inches. The poorly and very poorly drained Arveson and Borup soils are on positions similar to those of the Rockwell soils, but do not have an underlying layer of loamy glacial till or fine-silty lacustrine sediments.
DRAINAGE AND PERMEABILITY: Poorly or very poorly drained. Runoff is very slow or ponded. Permeability is moderately or moderately rapid in the upper part and moderate and moderately slow in the lower part. Depth to an apparent seasonal high water table is as high as 1.0 to 3.0 feet at some time from April through July in most years.
USE AND VEGETATION: Soils are commonly used to grow small grains. Native vegetation is a wet-site association of the tall grass prairie.
DISTRIBUTION AND EXTENT: Mainly in the Red River Valley of Minnesota and North Dakota. It is also in small glacial lake plains in western Minnesota and eastern North Dakota. Moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Stevens County, Minnesota, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are: mollic epipedon - surface to 9 inches (A horizon); calcic horizon - 9 to 19 inches (Bkg horizon); aquic moisture regime - low chroma immediately below the mollic epipedon.
ADDITIONAL DATA: Refer to MN Agr. Exp. Sta. Central file code No. 957 for results of some laboratory analysis of the typical pedon.