The Future of Humic Substances Research: Preface to a Debate.

For centuries, scientists have been probing the nature and dynamics of organic matter in soil and sediment. A prominent approach in this research has been to extract using a strong alkaline solution. The continuing merits of this time-honored approach, however, has prompted some recent debate. Does the study of humic substances, as defined by alkaline extraction, still promise further advances in our understanding of organic matter dynamics in terrestrial and aquatic systems? The two articles in this special section offer divergent responses to this question, providing a framework for enlightening discourse that will help direct future research. Receptive reading of these views will not only lead to clarity on a crucial issue but also offer insight into how best to learn from potentially divisive questions that will inevitably arise in the study of soil, a still mysterious medium.