Use of biochar for a sustainable viticulture: a study from field to glass

Vineyard soils are intensively managed to maximize both yield and quality, often resulting in reduced soil organic matter, compaction, and low microbial activity. Biochar has been proposed as a soil amendment to improve soil physical, chemical, and biological properties, enhancing water retention, nutrient dynamics, and microbial activity. This study investigated the effects of biochar amendment in a commercial vineyard of Ribolla Gialla, combining pedological, physiological, and microbiological analyses to assess its impact on soil properties, grapevine performance, and wine quality. Biochar improved soil water availability, particularly during critical phenological stages, and increased soil organic carbon content, confirming its potential for carbon sequestration and supporting long-term fertility. Enzymatic activities and soil microbial communities were positively influenced, with indications of enhanced carbon and nitrogen cycling, a reduction of potentially pathogenic taxa, and increased abundance of microbial groups associated with organic matter turnover. Despite these improvements in the soil environment, no consistent benefits were observed in grapevine productivity or wine quality. Bunches and berry weight, and total soluble solids were lower in biochar-treated plots, while titratable acidity remained unchanged, suggesting that Ribolla Gialla’s isohydric behavior may limit its response to improved water conditions. Soil salinity, as indicated by elevated electrical conductivity and exchangeable sodium in amended soils, and slightly higher levels of certain cations in must and wine, may have contributed to the reduced vine performance. Epiphytic microbiomes of leaves and berries were strongly shaped by the source matrix, showing higher diversity in leaves, but no significant changes due to biochar amendment were detected aboveground. These findings demonstrate that biochar effects are context-dependent and largely confined to soil properties. They highlight the importance of considering soil characteristics, biochar type, climatic conditions, and cultivar-specific physiology when evaluating vineyard amendments. Long-term field studies are required to further clarify the interactions among biochar, soil, microbial communities, and grapevine performance, to optimize its use for agronomic and environmental benefits.