LOCATION ROHRBECK MNEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, mesic Arenic Hapludalfs
TYPICAL PEDON: Rohrbeck loamy sand with a convex slope of 4 percent on a moraine in a cultivated field. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 6 inches; very dark grayish brown (10YR 3/2) loamy sand, light brownish gray (10YR 6/2) dry; weak fine granular structure; very friable; about 1 percent gravel; moderately acid; abrupt smooth boundary (5 to 9 inches thick).
E1--6 to 12 inches; dark brown (10YR 4/3) loamy sand; weak medium subangular blocky structure parting to weak very fine subangular blocky; very friable; many dark brown (10YR 3/3) organic coats; about 2 percent gravel; slightly acid; clear smooth boundary.
E2--12 to 25 inches; dark yellowish brown (10YR 4/4) loamy sand; weak medium subangular blocky structure parting to weak fine subangular blocky; very friable; many dark brown (10YR 4/3) organic coats; about 2 percent gravel; neutral; abrupt smooth boundary. (Combined thickness of E horizons is 12 to 33 inches.)
2Bt1--25 to 33 inches; dark yellowish brown (10YR 4/4) sandy loam; weak medium subangular blocky structure parting to weak fine subangular blocky; very friable; many dark brown (10YR 4/3) organic coats; few dark brown (10YR 3/3) clay films on faces of peds and in pores; about 8 percent gravel, 3 percent cobbles and stones; neutral; clear smooth boundary.
2Bt2--33 to 41 inches; light olive brown (2.5Y 5/4) loam; weak medium subangular blocky structure parting to weak fine subangular blocky; friable; few fine distinct grayish brown (2.5Y 5/2) Fe depletions; many olive brown (2.5Y 4/4) organic coats on faces of peds and in pores; few dark brown (10YR 4/3) clay films on faces of peds and in pores; about 5 percent gravel, about 5 percent cobbles; neutral; clear smooth boundary. (Combined thickness of 2Bt horizons is 6 to 26 inches)
2Bk--41 to 60 inches; light yellowish brown (2.5Y 6/4) sandy loam; weak medium subangular blocky structure; friable; common fine distinct yellowish brown (10YR 5/6) Fe concentrations and common light brownish gray (2.5Y 6/2) Fe depletions; few fine, irregular, soft, white (10YR 8/2) masses and threads of calcium carbonate distributed uniformly throughout the horizon; about 7 percent gravel; about 5 percent cobbles; strongly effervescent; slightly alkaline.
TYPE LOCATION: Meeker County, Minnesota; about 4 miles south and 2 and 1/2 miles east of the village of Eden Valley, Minnesota; 1,800 feet south and 2,000 feet east of the northwest corner of Sec. 31, T. 121 N., R. 30 W. USGS Forest City quadrangle, latitude 45 degrees 14 minutes 30 seconds N; longitude 94 degrees 29 minutes 45 seconds W., NAD27.
RANGE IN CHARACTERISTICS: The upper part of the series control section is intermittently saturated for at least 5 consecutive days during April to July and other periods of high rainfall in 6 years out of 10. Depth to free carbonates is between 30 and 50 inches. Thickness of the sandy mantle ranges from 20 to 40 inches. The argillic horizon is formed in the glacial till, and averages between 16 and 24 percent clay. Content of sand ranges from 45 to 65 percent. That part of the solum developed in the sandy mantle has as much as 2 percent rock fragments consisting mostly of gravel and a few scattered cobbles. The 2Bt horizon and the underlying glacial till have 8 to 15 percent by volume rock fragments ranging from mostly gravel and cobbles with a few widely scattered stones and boulders. The rock fragments are of mixed lithology.
The Ap horizon has value and chroma of 2 or 3. It has value of 5 or 6 when dry. An A horizon ranging from 4 to 8 inches thick is in non-cultivated areas. They are loamy sand or loamy fine sand. Reaction is slightly acid or neutral.
The E horizon has value of 3 or 4 and chroma of 2 or 3. It has value of 6 when dry. It is sand, fine sand, loamy sand or loamy fine sand. Reaction is moderately acid or slightly acid.
The 2Bt horizon in the upper part dominantly has hue of 10YR, with value of 4 or 5 and chroma of 3 or 4. Some pedons have 2.5Y hue with value of 4 or 5 and chroma of 4. The lower part of the 2Bt horizon has hue of 10YR or 2.5Y, value of 4 or 5 and chroma of 3 or 4. Low chroma Fe depletions range from few to common in the lower part of the horizon. The 2Bt horizon is sandy loam, fine sandy loam, loam or sandy clay loam. Ped exteriors have clay and organic matter coatings that range from few to common. It is moderately acid to neutral.
The 2Bk horizon has hue of 2.5Y, chroma of 5 or 6 and chroma of 3 or 4. Mottles with chroma of 2 or less are few. It is sandy loam or fine sandy loam. It has 12 to 18 percent clay and 45 to 65 percent sand. It is slightly alkaline.
COMPETING SERIES: These are the Delton, Metea, Okee, Ormas, Puchyan and Seward series. The Delton and Seward soils have more than 18 percent clay in the lower part of the series control section. Metea soils have an average of more than 24 percent clay in the argillic horizon. Okee soils have 7.5YR or redder hues in the argillic horizon. The Ormas soils have more than 15 percent gravel in the lower part of the series control section. The Puchyan soils have less than 20 percent sand in the lower part of the argillic horizon.
GEOGRAPHIC SETTING: Rohrbeck soils are on plane or convex positions on summits, shoulders and backslopes of moraines. Their slopes range from 1 to 6 percent. They formed in a sandy eolian or outwash mantle and in the underlying calcareous, loamy glacial till of the Wadena sublobe of the Wisconsin glaciation. Mean annual air temperature ranges from 45 to 48 degrees F. Mean annual precipitation is 26 to 28 inches. The number of frost free days ranges from 145 to 155 days. Elevation above sea level is from 1100 to 1300 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chelsea, Granby, Koronis and Lundlake soils. Excessively drained Chelsea soils are more than 40 inches to horizons formed in glacial till and are on similar landscape positions. Well drained Koronis soils are formed entirely in loamy glacial till and are closely associated on nearby convex positions. Poorly drained Granby soils are sandy to below 40 inch depth and are on plane and slightly concave positions. Very poorly drained Lundlake soils formed entirely in glacial till.
DRAINAGE AND PERMEABILITY: Moderately well drained. Surface runoff is moderately low or moderately high. Permeability is very rapid in the sandy mantle and moderately rapid in the underlying material. An apparent seasonal high water table is at 2.5 to 4 feet at some time during April to July in most years.
USE AND VEGETATION: Most areas of these soils are cropped to corn and soybeans. A few areas are in pasture and woodland. Native vegetation is Northern hardwoods and tall grass prairie.
DISTRIBUTION AND EXTENT: Central Minnesota. These soils are of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Meeker County, Minnesota, 1995.
REMARKS: Diagnostic features recognized in this pedon are: ochric epipedon - the zone from the surface to a depth of 25 inches; (Ap and E horizons); argillic horizon - the zone from a depth of 25 to 41 inches (2Bt horizons); arenic subgroup - loamy sand from surface to 25 inches; udic moisture regime.
ADDITIONAL DATA: Soil Interpretation Record MN0719.