Webster soils are in cooler and drier climates and typically have thinner sola. Competing series may change as they are updated to the 8th Edition of Keys to Soil Taxonomy. The Free , Kossuth , Reddick , Springerton , and Wolcott series have not been updated to the 8th Edition of Keys to Soil Taxonomy, but were competing series to Marengo under previous taxonomic classification. Free soils have more than 15 percent rock fragments in the lower part of the solum. Kossuth soils have more than 35 percent clay in the upper part of the series control section.
Reddick soils are more alkaline than slightly acid in the upper part of the series control section.
Springerton soils have warmer temperatures in the temperature control section at a depth of 20 inches, and have individual subhorizons that average more than 50 percent sand in the lower part of the series control section. Wolcott soils do not have rock fragments dominantly of sandstone, siltstone, and shale. Marengo soils formed in loamy till on Wisconsinan age till plains. Slope gradients are less than 2 percent. Climate is humid and temperate.