sábado, 4 de agosto de 2012

Viticulture of Sherry in Jerez


The climate of the Jerez region is strongly influenced by its proximity to the Atlantic. Sea freezes from the gulf of Cádiz alleviate externes. The oceanic influence is strongest in the coastal towns of Sanlúcar de Barrameda and Puerto de Santa María, where temperatures in July and August may be 10º C/18 °F lower than in Jerez, 20 km/12 miles inland.

Winters are mild and damp with most of the region’s annual average rainfall of 650 mm/25 falling between late autumn and spring. There is almost no rainfall between June and October. Summer temperatures often reach 30 ºC inland, occasionally rising to 40 °C with the levante, a piercing, dry, dusty wind from the south east.

The vines are sustained during the dry sumer months by the porous, white albariza soils that are at the heart of the Jerez DO. The demarcated region is roughly triangular extends from the town of Chiclana de Frontera in the south east to the Guadalquivir in the north west, tapering inland. However, the best albariza soils cover a strech or rolling country north of the river Guadalete between Jerez and Sanlúcar de Barrameda. These outcrops of albariza are known collectively as Jerez Superior and the majority of these vineyards are within the municipality
of Jerez de la Frontera, with secondary pockets around Sanlúcar de Barrameda, Puerto de Santa Maria, Chipiona, and Rota.

The albariza zone is divided into subdistricts. Those with the deepest, but not necessarily the most calcareous, albariza soils like the famous Balbaina, Macharnudo, Carrascal, and Añina districts produce the most delicate wines for the finest Finos and Manzanillas. The most calcareous soils, known as tajón, are generally unsatisfactory for viticulture because of potential chlorosis. The finest albarizas include a proportion of sand and clay and tend to vary with depth, with a limestone content of 25 % or more on the surface rising to 60 % in the rooting zone 80 to 100 cm/39 in below the surface. In between the hills of albariza, barro soils have more clay and produce fuller, coarser wines and slightly higher yields. On the sandy soils known as arenas, yields are twice as great as on the albariza but the quality of the wine is poor. Arena soils were popular with growers at the end of the 19 century as the phylloxera louse found it difficult to survive in sand. However, with the recent rationalization of the sherry industry, viticulture is increasingly concentrated on the albariza soils and over 80 % of the region’s vineyards are situated in Jerez Superior.


In the 19 century, a variety of different vines were planted around Jerez but, after phylloxera wiped out most of the vineyards in the 1890s, many varieties were never replanted. Only three varieties are now authorized for new vineyards in Jerez: palomino, pedro ximénez, and muscat of Alexandria. Of these, Palomino is the most important and accounts for around 95 % of the total vineyard area. There are in fact two types of Palomino: Palomino Basto (also known as the Palomino de Jerez) and Palomino Fino. Palomino Basto has largely been supplanted by Palomino Fino, which provides better yields and is more resistant to disease. Palomino Fino has proved to be a particularly versatile grape and is used for most types of sherry.

Moscatel Gordo Blanco (Muscat of Alexandria) represents about 3 % of the Jerez vineyard and is planted principally in the more sandy soils on the coast around Chipiona. It is mainly used for sweetening although some producers make and market their own varietal Moscatel wines.

Pedro Ximénez (known for short as PX) has given ground to Palomino and currently represents less than 100 ha/250 acres of vineyard since Palomino Fino is easier to cultivate. Most sweet wine is now made from Palomino although some smaller producers still maintain small PX Soleras which they bottle as a varietal wine. In recent years, special dispensation has been granted for the, now routine, importation of PX must from montilla-moriles to compensate for the lack of PX in Jerez.

Since phylloxera swept through Jerez, all vines have been grafted onto American rootstocks which are selected according to the soil’s lime content. In the past vines were planted in a hexagonal pattern known as tresbolillo but, with increasing mechanization, vineyards are planted in orderly rows at a maximum vine density of 4,100 vines per ha (1,660 per acre). Yields from the Palomino are high, although the maximum permitted yield for the entire DO has been set at 80 hl/ha (4.5 tons/acre).

With the onset of mechanization, modem vineyards are trained on wires, although the pruning method, called vara y pulgar, is unchanged, and similar to the guyot system. A vara (meaning stick or branch) with seven or eight buds produces the current year’s crop. The pulgar (meaning thumb) is a short shoot with one bud which will produce the following year’s vara.

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