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' Official Series Description - CORDOVA Series Page 2 of 3 loam, silty clay loam, or clay loam. Eluviation is evident in some pedons by a few porous coatings on the faces of pods in the lower A and/or upper B horiozns. ' Some pedons have AB horizons. The Btg horizon has a matrix with hue of IOYR to 5Y, value of 3 to 5, value of 3 is only in the upper part, and chroma of 1 or 2. Some pedons have a BA horizon. The B horizon typically is silty clay loam or clay loam but ranges to loam in the lower part. The upper 20 inches of the argillic horizon averages between 28 to 35 percent clay and exceeds 15 percent fine sand and coarser. The B/A clay ratios range ' from 1.2 to 1.4. A Bk horizon is present in some pedons. The C horizon has a matrix with 5Y or 2.5Y hue, value of 4 to 6, and chroma of 2 to 4. It is loam or clay loam and is slightly alkaline or moderately alkaline. COMPETING SERIES: These are the B r , Berville, Brookston, Buntin ville, Clackamas, Hamel, Jameston, Marengo, Millgrove,Navan,Nosoni, Rensselaer, and Westland series. Barry soils have less than 27 percent clay in the control section. Berville soils contain more than 6 percent gravel in the control section. Brookston soils are more moist in the soil moisture control section during the 120 days following the summer solstice and have less montmorillonite in the lower part of the series control section. Buntingville, Clackmas, and Nosoni soils are drier in the soil moisture control section during the 120 days following the summer solstice. Hamel soils have A horizons 16 to 27 inches thick and and chroma of 1 or less in the upper B horizons. Jameston soils have very firm till beginning at depths ' ranging from 18 to 30 inches. Marengo soils typically have thicker sola,contain appreciable amounts of sedimentary rock fragments in the silty clay lower B and C horizons, and are more moist in the soil moisture control section. Millgrove soils have up to 15 percent gravel in the upper part and 7 percent or more in the lower part of the control section and very poorly drained..Navan soils have than 35 percent more clay in the lower B and C horizons. Rensselaer soils have reaction greater than 6.1 in the upper part of the control section, are more moist in the moisture control section and are poorly drained. Westland soils have 7 percent or more gravel in the lower part of the control section. GEOGRAPHIC SETTING: The Cordova soils have slightly concave to slightly convex slopes on broad flat ridge tops in rolling moraine areas or on lower lying areas in ground moraines and till plains. Slope gradients are 0 to 2 percent. Soils formed mostly in friable, calcareous, loamy till of Late Wisconsinan age. However,the upper part of the sola in some pedons is from modified glacial till or ' drift. The mean annual temperature is about 45 to 52 degrees F. Mean annual precipitation is about 26 to 32 inches. ' GEOGRAPHICALLY ASSOCIATED SOILS: The main ones are the Dundas, Lester, and Le Sueur soils. These soils formed in materials similar to those of the Cordova soils and are members of a hydrosequence with the Cordova soils. The well drained Lester soils are on nearby undulating to hilly ' slopes. The moderately well to somewhat poorly drained Le Sueur and the somewhat poorly to poorly drained Dundas soils are on nearby higher positions. The poorly drained Webster and Hamel soils and the very poorly drained Glencoe soils are a nearby associate in a few places. DRAINAGE AND PERMEABILITY: Poorly drained. Surface runoff is low. Permeability is moderately slow. iUSE AND VEGETATION: Most of the soil is cleared, drained and cropped to corn and soybeans. A http://ortho.ftw.nrcs.usda.gov/cgi-bin/osd/osdname.cgi?-P 11/2/2004