Soil science simplified / Milo I. Harpstead, Francis D. Hole, William Bennett ; illustrated by Mary Bratz-Stephens. Harpstead, Milo I., 1930- Hole, Francis Doan, 1913- Bennett, William F. Soil science. S591 .H28 1988 631.4 19 HAS Includes index. Ames : Iowa State University Press, 1988. 1988. 1988 Text vii, 196 p. : eng