The soil component of terroir

Edoardo A.C. Costantini [CRA – Consiglio per la ricerca e sperimentazione in agricoltura – Centro di ricerca per l’agrobiologia e la pedologia, Firenze]

This review paper is aimed at drawing the main traits of an interdisciplinary research field, bridging different branches of pedology with crop sciences and food analysis. The terroir concept is introduced, giving a special emphasis to the research works that have investigated the role played by soil on terroir recognition. Water and oxygen availability are the main drivers of the soil effect on terroir, but other soil functional qualities for wine grape as well as other quality products (olive oil, apple, pomegranate, potato, carrot, truffle, beer, coffee, and tobacco), are reported. Soils of the well-known terroirs are often characterized by moderate water, oxygen and nutrient supply, probably regulated by a specific biodiversity, able to assure the target qualitative result without massive integration of fertilizers. Thus, a challenge for soil scientists is to provide the evidences and the tools to farmers in order to let them select, maintain and carefully support the soil of terroir. Best terroirs are rooted in soils that in most years produce moderate yield but of good quality, without massive integration of fertilizers or unsustainable risks for soil quality conservation. Then farming systems were tailored to maintain and carefully support the agro-ecosystems that were created by this harmonic synergy between nature and man.Nowadays, developing new premium terroirs without making many errors is only possible by means of a thoroughly and detailed knowledge of the different components of terroir, giving a pivotal emphasis to soil. Yet spatial variation of soils is often great, especially in Mediterranean countries, because of natural as well as anthropic causes. Setting up methodologies and technologies capable to obtain a detailed soil mapping of soil functional properties at reasonable cost and time is one of the main objective of the research in this field. Many efforts are currently spent to better integrate different kinds of proximal and remote soil sensors, either between them and with other state controlling factors (topography, climate, vegetation).A special focus is then given to the new frontiers that soil sciences can offer to this research field, in particular, on the new materials and methods that can be used to understand and measure the soil influence on wine grape and other quality crops. Advances are shown on: i) the use of proximal and remote soil sensors, models, and statistical analysis, ii) the spatial and temporal assessment of nutrient availability and soil biology, iii) the adoption of the carbon isotope ratio to assess the stress suffered from the plant during the growing season, and iv) the new methodologies to trace the food origin.

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