Abstract Recent publications in soil science have reopened discussions over how soil and soil science should be defined, reflecting productive tension between historical constructs and the evolving frontiers of the discipline. While new definitions offered over the past decade provide valuable perspectives, they inevitably rely on past conventions and often leave certain realms of “what counts” as soil ambiguous and open to interpretation. Answering the recent calls by McBratney and Hartemink, Hartemink and McBratney, and Ghezzehei and Berhe, this commentary provides three foundational proposals to the definition of soil that expand the frontiers of soil science. These proposals are as follows: (1) consistently recognize zero‐states in all soil‐forming factors, (2) define soil's lower depth as being until unit‐ or zero‐gradient potentials (i.e., layer of active fluxes) within the surrounding regolith, and (3) broaden soil's definition beyond rocky domains (refractory minerals) of Earth or other refractory‐derived planetary bodies to include fully or partially unconsolidated volatile minerals (ices) as parent materials for all celestial body surfaces, which I propose as “soils made from ices” or págousols. Furthermore, support is given to the discipline's century‐old approach of a dual‐definition framework to accommodate Earthbound regulatory and practical purposes, and another, broader definition for scientific discovery at the discipline's fundamental frontier. These proposals offer complementary perspective toward definitions of soil that are inclusive, precise, and forward‐looking.
Aaron Lee M. Daigh (Sun,) studied this question.