The Ruma series consists of very deep, well drained, moderately permeable soils formed in loess, or in loess and the underlying silty pedisediment on till plains. Slope ranges from 2 to 35 percent. Depth to the base of the argillic horizon is 40 to 70 inches, and the depth to the base of soil development is greater than 80 inches. The particle-size control section averages 27 to 35 percent clay and averages less than 7 percent sand.
Texture is silt loam or silty clay loam.
Clay content is 18 to 35 percent. Sand content is less than 7 percent. Reaction is moderately acid to neutral, depending on the liming history. The E, EB, BE horizons, where present, have value of 4 or 5 and chroma of 2 to 4. Clay content is 15 to 27 percent.