Biochar From Viticultural Residues: A Review of Physicochemical Properties and Applications

Viticulture generates substantial quantities of organic residues, many of which remain poorly or nonvalorized. These by‐products include grape seeds, grape stems (stalks), grapevine trunks (stumps or wood), grape skins (husks), and especially grape marc and prunings, which are the primary feedstock used for biochar production. Although numerous studies have established that both feedstock type and pyrolysis temperature affect biochar physicochemical properties, existing reviews generally addressed biochar properties and applications in a broad context, without specifically focusing on viticultural by‐products. This meta‐analysis compiles data from 316 biochar samples reported across 114 studies, aiming to synthesize current knowledge on biochars derived from viticultural residues. It specifically examines (1) how biochar physicochemical properties vary with feedstock type and pyrolysis temperature, and (2) the potential applications of these biochars. Results indicate that feedstock type primarily influences nitrogen content, combustion‐related parameters, and mineral composition. In contrast, pyrolysis temperature predominantly affects pH, hydrogen content, volatile matter, yield, and stability—particularly at higher temperatures (> 600°C). Both factors also significantly influence specific surface area (SSA), carbon and oxygen contents, fixed carbon, and ash content. Overall, viticultural biochars are mainly used as adsorbents for trace elements and as amendments for soil improvement, although emerging industrial applications, particularly for seed‐derived biochars, are gaining attention. This work provides the first comprehensive overview of biochars from viticultural by‐products, supporting their broader adoption within circular bioeconomy strategies for decarbonization and climate change mitigation.