Volcanic eruptions are generally viewed as agents of destruction, yet they provide the parent materials from which some of the most productive soils in the world are formed. The high productivity results from a combination of unique physical, chemical and mineralogical properties. The importance and uniqueness of volcanic ash soils are exemplified by the recent establishment of the Andisol soil order in Soil Taxonomy. This book provides the first comprehensive synthesis of all aspects of volcanic ash soils in a single volume. It contains in-depth coverage of important topics including terminology, morphology, genesis, classification, mineralogy, chemistry, physical properties, productivity and utilization. A wealth of data (37 tables, 81 figures, and Appendix) mainly from the Tohoku University Andisol Data Base is used to illustrate major concepts. Twelve color plates provide a valuable visual-aid and complement the text description of the world-wide distribution for volcanic ash soils.This volume will serve as a valuable reference for soil scientists, plant scientists, ecologists and geochemists interested in biogeochemical processes occurring in soils derived form volcanic ejecta.