Physicochemical Characterization of Vineyard Stump-Derived Hydrochars and Pyrochars and Preliminary Grapevine Tolerance Screening

This study explores a circular economy strategy for vineyard residue management through the conversion of pruning biomass into carbonaceous materials by hydrothermal carbonization (HTC) and pyrolysis (PYR), with and without iron (Fe) addition. A preliminary pot-based vegetation experiment was conducted as a screening assay to assess initial plant tolerance and exclude evident phytotoxic effects. Chlorophyll index values in grapevine leaves remained within physiological ranges across treatments and sampling dates, although no consistent treatment-related trends could be established. Overall, the results provide a physicochemical characterization of the carbonaceous materials derived from vineyard residues and demonstrate their initial compatibility with grapevine cultivation under controlled conditions. This work lays the groundwork at the material level for future, more comprehensive studies that integrate long-term soil, plant, and field assessments.