The geological and geomorphological events that determine the soil functional characters of a terroir

The geology of a region is deemed to be an important component of terroir, as it influences the shape of the landscape and the climate of vineyard. The nature of rock and the geomorphological history of a terroir affect soil physical and chemical composition through a dynamic interplay with the changes of climate, vegetation and other living organisms, as well as with man activities.
This work is aimed at demonstrating that the soil functional characters which differentiate the terroirs of a denomination of origin area are products and witnesses of the geological and geomorphological events, natural and human induced, which occurred in that trait of land. The final scope being enhancing the awareness of stakeholders about the possible environmental and economic losses that can derive from an irrational soil management, which can lead to the worsening or loss of irreproducible soil functional characters of the best terroirs.
The work makes reference to the denomination of origin ”Vino Nobile di Montepulciano”, where a four years research was conducted on the relationships between soil characteristics and the viticultural and oenological behaviour of Sangiovese vine. The soils of the Montepulciano vineyard range notably in fertility conditions and functional characters, also when formed on the same kind of sediments, in particular as for water and oxygen availability. The grape production at vintage, as well as the organoleptic characteristics of the wine, resulted strictly interactive with the different soils. The wines obtained on a first group of soils had a good structure and typicity, but the stability of wine sensorial profile during the years was low. A second group exhibited good structure, typicity, and a good stability of wine sensorial profile. A third group had low structure, low typicity, and high astringency all the years of trial.
The oldest soils of the Montepulciano vineyard started their formation during the Pleistocene. During the medium Holocene, man deeply influenced pedogenesis, but it is during the last 50 years that the intensity of the man action reached its maximum. Pre-plantation activities of the new specialized vineyards upset the land, leaving very different effects on soil functional characters. Where the soils before vine plantation were deep and rather homogeneous, soil functional characters remained the same, whereas they changed significantly where soils were shallower. Shallow soils on marine clays, in particular, resulted very vulnerable.
Best soils for the Nobile di Montepulciano wine production, that is, those belonging to the second group, were old soils, formed as a consequence of particular natural and human induced geomorphological events. Therefore they should be considered cultural heritages.