Hidden potential for mixotrophy in soil protists

Mixotrophy, the ability of a single protist to combine phototrophy and phagotrophy, is widely recognized as an important functional strategy in aquatic ecosystems, where it shapes food-web structure and carbon cycling. In soil, however, mixotrophy remains largely overlooked despite increasing evidence for trophic flexibility among protists. Here, we argue that this neglect may reflect conceptual and methodological limitations rather than ecological absence. We highlight inconsistencies in trait-based classifications, delineate feeding traits that enable certain forms of mixotrophy, and evaluate soil microhabitats that support mixotrophic activity. Recognizing mixotrophy in soil challenges traditional views of distinct trophic categories and reveals its potential contributions to soil carbon fluxes. Incorporating mixotrophy into soil ecology is therefore essential for developing mechanistic and predictive models of terrestrial ecosystem functioning.