Although soil ecology has benefited from recent advances in describing soil organism trophic traits, large scale reconstruction of soil food webs is still impeded by (1) the dissemination of most data about trophic interactions and diets into distributed, heterogeneous repositories, (2) no well-established terminology for describing feeding preferences, processes, and resource types, and (3) much heterogeneity in the classification of different soil groups, or absence of such classifications. Soil trophic ecology could therefore benefit from standardisation efforts. Here, we propose the Soil Food Web Ontology as a new formal framework for representing knowledge on trophic ecology of soil organisms. This ontology captures the semantics of trophic concepts, including consumer-resource interactions, feeding preferences and processes, and provides a formalisation of trophic group definitions. The ontology can be used to add semantic annotations to trophic data, thus facilitating the integration of heterogeneous datasets. It also provides lexical resources that can support the development of information extraction tools to facilitate literature-based datasets creation. Finally, it enables automatic and consistent classification of soil organisms based on their trophic relationships. We argue that, by harmonising the terminology and underlying concepts of soil trophic ecology, our ontology allows for better use of available information on the feeding habits of soil organisms and sounder classifications, thus facilitating the reconstruction of soil food webs and making food web research more accessible, reusable and reproducible.