A common vision that may serve as an enabler for sustainable development, environmental preservation, and fighting hunger in the world, is the involvement, collaboration and coordination of activities dealing with the production, organisation and exchange of agricultural knowledge. Numerous technical and subject experts are working on related topics, tackling with issues such as classifications & taxonomies, controlled vocabularies, thesauri, authority files, glossaries, metadata specifications and their application profiles, as well as ontology-driven applications. The general aim of this special issue is to assess the current status and technologies, as well as to outline the major challenges and future perspectives, related to agricultural knowledge production, organization, and exchange from a Semantic Web perspective. It aims to provide an overview of the state of the art in this field, by including a wide range of interdisciplinary contributions. Overall, it aims to outline the rich potential of the agricultural knowledge domain as an application field for advanced metadata- and semantic-driven systems and services.