TERROIR OF TUSCANY, ITALY – EXAMPLES FROM MONTALCINO AND POGGIBONSI

Tuscany in central Italy is famous for wines made from the Sangiovese grape; the two best known examples are Chianti Classico and Brunello di Montalcino. To understand the terroir of these wines a prime vineyard from each area was studied to identify characteristics of climate, soil, and bedrock that might correlate with wine quality. The Barbi vineyard of Fattoria dei Barbi produces wine classified as Brunello di Montalcino in favorable years and is located about 1 km SW of the city of Montalcino in Siena Province at an elevation of 480 m in the middle of the Orcia River basin. The basin is floored by Triassic limestone and allochtonous Oligocene-Miocene calcareous siltstone/shale. Rapid uplift and extension in the late Pliocene produced fluvial deltas and marine sediments, that in turn are overlain by Pleistocene conglomerates. Mean annual temperature is14°C and precipitation averages 70 cm, mostly in May, Oct., and Nov. Soils are Haplic Calcisols and average 1 m thick, consisting of 19% sand, 44% silt, and 37% clay. Moderately weathered gravel (5-20 mm) and cobbles from the underlying bedrock are locally present up to 15%. pH averages 8.0, controlled mainly by CaCO3 of 25-30% with 4.4-7.8% active CaCO3 and 0.20-0.29% organic carbon. Measured exchange complexes (meq/100g) are Ca=21.3, Mg=4.1, Na=0.3, K=0.3. The C/N ratio is 7.3. The Fonti vineyard of Fattoria Le Fonti produces Chianti Classico and Riserva in favorable years and is located about 5 km NE of the city of Poggibonsi in Siena Province at an elevation of 260 m. The climate is similar to Montalcino but the bedrock is predominantly Eocene thin-bedded marine calcareous sandstone. Soils are Skeleti Calcaric Regosols and Cambisols and range from less than 30 cm thick at the top of the vineyard to > 1 m at the graded bottom of the vineyard. The soil averages 20% sand, 58% silt, and 22% clay, with locally abundant moderately weathered flaggy cobbles of underlying bedrock. pH averages 8.2 with CaCO3 of 10-12%, 1.1-1.2% active CaCO3, and 0.15-0.37% organic carbonate. Measured exchange complexes are Ca+Mg=14.02, Na=0.14, K=0.19. The C/N ratio is 3.6. Both vineyards are characterized by free drainage of nutrient-poor, calcic soils that are not irrigated. Moisture from winter rains is partly retained by moderate clay contents but the overall summer dry conditions result in relatively low yields and concentrated flavors.