Differing Views of Soil and Pedogenesis by Two Masters: Darwin and Dokuchaev
Donald L. Johnson and Randall J. Schaetzl
Charles Darwin and Vasily Dokuchaev made early and important, but quite different, contributions to pedogenic theory. Their major contributions were both written as books - Darwin’s 1881 The Formation of Vegetable Mould, Through the Action of Worms, With Observation on Their Habits, and Dokuchaev’s 1883 Russian Chernozem. Although most soil scientists are familiar with Dokuchaev’s legacy and lasting impact, far fewer know about or value equally Darwin’s “worm book.”
Dokuchaev’s factorial approach to soil science, drawn from observations across the Eurasian steppe, helped map, classify, and place economic value on soils, while also providing key insight into their formation. This approach gained visibility in the 1930s and 1940s, when personnel at the U.S. Department of Agriculture, and some academic pedologists, recognized its utility for soil survey and for interpreting pedogenesis. Hans Jenny’s 1941 book, Factors of Soil Formation, helped the model to gain acceptance, and it eventually became entrenched as the core pedogenic model for North America, if not the world. Dokuchaev’s legacy is tied to this model. Alternatively, Darwin’s main contribution to the field was to shed light on soil processes, particularly faunal mixing (bioturbation) and the textural sorting it can produce. Although Darwin’s findings fostered an array of multidisciplinary studies on pedogenic processes during the ensuing 50 years, his work languished in the broad shadow cast by Dokuchaev’s model. In 1975, Darwin’s ideas reappeared in Soil Taxonomy - associated with rudimentary biomantle concepts. Recently, empowered with new concepts and language, bioturbation concepts have gained considerable traction.
We briefly summarize the backgrounds of Darwin and Dokuchaev, and compare their fundamentally different approaches to pedogenesis. But insofar as Dokuchaev’s approach is more mainstream, we emphasize Darwin’s, for balance. We show how Darwin’s model, updated with current understandings of biomantle formation, is allowing new questions to be asked about pedogenesis and landscape evolution, and formerly intractable ones to be answered. We stress the profound role of conceptual models in guiding explanatory thought, and end by positing that both Darwin’s and Dokuchaev’s approaches, while different in their basic structure and goals, provide together a more complete view of pedogenesis than either can do singly.