The Case Basse attack is not the first time in recent years that Brunello di Montalcino has hit the headlines. In 2008, "Brunellogate" revealed the existence of a three-year inquiry into claims that some producers were supplementing sangiovese – the only variety permitted – with other grapes.

Some reports have suggested that last weekend's attack on the Case Basse winery could have been motivated by revenge over whistle-blowing by the owner, Gianfranco Soldera – allegations that he strongly denies.

But is sangiovese actually the best-suited grape for the large Brunello di Montalcino region? In this extract from her latest book, "Brunello di Montalcino," Italian wine expert Kerin O'Keefe considers the question:

“Brunello’s entire production area centers on the expansive commune of Montalcino. This medieval hilltop town, whose name derives from the Italian translation of the Latin Mons Ilcinus (Mount Ilex), the ancient Latin name of the hill on which the town perches, and referring to the ilex or holm oak trees that still populate the surrounding woods, lies roughly 40 kilometers (25 miles) south of Siena and just over 40 kilometers (25 miles) as the crow flies from the Tyrrhenian Sea.

Montalcino occupies a central position within the Province of Siena, though it is far away from busy roads and immersed for the most part in unspoiled countryside. Whereas the ancient town center, dominated by its fourteenth-century fortress, is tiny, the entire municipal area, the largest township in the province, includes several hamlets and stretches across 24,362 hectares (60,200 acres), with 70 percent of the area defined as hilly, 29 percent flat, and 1 percent mountainous.

Half of the territory is still covered by dense woods and fallow land while 10 percent is dedicated to olive groves and 15 percent to vineyards. The rest is pasture land or is cultivated with various crops, mostly grain. Of the 3,500 hectares (8,645 acres) of vines planted throughout the large territory, 2,100 hectares (5,187 acres) are registered to Brunello, 510 hectares (1,260 acres) as Rosso di Montalcino, 50 hectares (124 acres) planted to Moscadello, 450 hectares (1,111 acres) to Sant’Antimo, and the rest planted with IGT (Indicazione geografica tipica) vines.

Montalcino’s rambling surface area resembles a square 16 kilometers (10 miles) wide, delimited by the Orcia, Asso, and Ombrone Rivers. Within these boundaries four major slopes rise to form a ridge, peaking at 667 meters (2,188 feet) above sea level, with Mount Amiata in the southeast protecting the slopes from hail and violent storms. When compared to Chianti Classico to the north and Montepulciano to the east, both further inland, Montalcino enjoys a decidedly more Mediterranean climate.

Sangiovese benefits from the warmer summertime temperatures and drier weather that lead to ideal berry maturation, while day and night temperature differences generate complex aromas—perfect ripening conditions for this temperamental variety. It is no coincidence that of all Tuscany’s vaunted denominations only Brunello di Montalcino, and Rosso di Montalcino, the denomination’s second wine that is made to be drunk young, are required by law to be made entirely with Sangiovese, or as the Italians say, Sangiovese in purezza.

However, although Sangiovese excels in select parts of Montalcino, it does not perform as well throughout the whole denomination thanks to the dramatic differences within the large growing zone, which is remarkably diverse for a single township. Among the denomination’s vivid variations, vineyard altitude, which ranges from just above sea level to over 500 meters (1,640 feet), is a crucial factor in Sangiovese’s performance.

Although the variety produces more complex and age-worthy wines in the higher altitudes, when cultivated too high the vine can have trouble ripening in difficult years. Montalcino also boasts several distinct microclimates with sharp contrasts in summer temperatures and annual rainfall, which noticeably affect the grape’s ripening ability and dictate when growers start the harvest. In the most scorching areas around Sant’Angelo Scalo, the Brunello harvest begins ten days to two weeks earlier than in the cooler, elevated areas. Subzones also react in remarkably different ways during years with extreme or adverse climatic conditions. Though select areas throughout the entire growing zone can produce beautifully balanced Brunellos in outstanding vintages like 2004, in difficult years like the washout 2002 and the torrid 2003, the vintage will have markedly divergent outcomes in the various subzones, a fact generally ignored by the press, which, in the absence of official zoning, tends to treat the area as a uniform whole.

Montalcino also boasts a phenomenal array of soil types within its confines. Seeing that no denomination-wide soil study has ever been undertaken in Montalcino, it is virtually impossible to say how many types of soils exist, although the Banfi estate, which has performed soil studies in its vineyards, declares that it has identified twenty-nine different soil types on its property alone. As geologists point out, Italy was formed by the collision between the European and African plates.

Much of Tuscany forges what is known as a suture of the intercontinental impact, where over a period of millions of years, a stacking up process of the land mass created the Apennine Mountains and the many high hills that dominate this part of the region. While it could be argued that this event largely created the same situation in other parts of Tuscany that are relatively close to the sea, Montalcino is extremely unusual for a unique phenomenon whereby the sea retreated and returned several times, thereby generating a highly uncommon soil composition in parts of the denomination. As a result, according to experts, Montalcino’s growing zone boasts one of the most complex and varied soil profiles in the world.

Certainly one reason for Montalcino’s composite soils lies in the fact that the celebrated hill was formed in different geological eras. While this makes it difficult to make sweeping generalizations, in the broadest terms the higher reaches of the denomination just south of the town center have the oldest soil since they were the first land masses to rise above the receding oceans that once covered the earth, while the soil in the extreme south-western lowlands are the youngest soils.

Soils in the middle altitudes, on the other hand, are a complex mix of both. The younger soils that dominate the plains in the southwest, comprising alluvial deposits from the relatively recent Quaternary period (up to 1.8 million years ago) and Pliocene epoch consist of sand, clay, mud, and marine sediment. Heading further uphill, the terrain is clay-enriched with calcareous fossil material usually attributed to the Miocene-Oligocene epochs; while in the upper part of the territory soil is moderately stony, mixed with sand and rich in lime where the well-draining soil is very old (Cretaceous-Eocene) and can restrain the youthful exuberance of productive grapevines.

However, the reality in Montalcino is far more complex than this simplistic breakdown, and the growing zone’s pedological (soil) situation, is extremely intricate. According to Edoardo Costantini, a professor of pedology and geopedology at the University of Siena for twenty years and the lead researcher of agrobiology and pedology at Florence’s CRA-ABP Research Center (Centro di ricerca per l’agrobiologia e la pedologia), not only is Montalcino complex because it was formed in different geological ages, but because parts of the growing zone benefit from a highly rare natural phenomenon.”

* "Brunello di Montalcino: Understanding and Appreciating One of Italy’s Greatest Wines," by Kerin O’Keefe, is published by the University of California Press at $39.95 (£27.95).

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