Terroir — the distinctive character that a vineyard imparts to its wine — has been conceptualized as a property of the ground. The word itself derives from terre, earth. Winemakers speak of chalky soils, volcanic substrates, mineral notes. The assumption: the taste of the place is the taste of the dirt.
A 2026 study in npj Biofilms and Microbiomes disentangled the microbial contributors to vineyard-specific character across multiple sites. They measured microbial communities in the soil, on the leaves, and on the berry surfaces, asking which community carried the strongest site-specific signature. The soil microbiome varied across sites, as expected. But the berry-associated fungi showed the strongest location-specific fingerprint — stronger than the soil itself. The organisms living on the grape surface, not the organisms in the ground, are the primary carriers of what winemakers have been calling terroir.
The structural insight: the part of the system closest to the product carries more location information than the part everyone assumed was the source. The soil is the origin story. The berry surface is the actual signature. They are not the same.
This matters because it reverses the causal direction that viticulture has operated under. Interventions aimed at preserving terroir have historically focused on soil management — organic farming, minimal tillage, composting. These may still matter, but if the strongest microbial fingerprint lives on the berry, then canopy management, humidity control, and spray timing may do more to preserve (or destroy) terroir than anything done to the ground. The actionable surface is different from the assumed surface.
The pattern generalizes. When a system has multiple layers — substrate, intermediate, surface — the deepest layer gets the most explanatory weight because it seems most fundamental. But information about origin can accumulate at any layer, and may accumulate most strongly at the layer with the most environmental exposure. The berry sits in the air, not in the soil. It encounters the local climate, the local insects, the local windborne spores. Its surface is an integrator of everything the vine experiences above ground. The soil integrates what happens below. Neither is wrong. But one is closer to the wine.