In viticulture

Viticulture

Viticulture is the science, production and study of grapes which deals with the series of events that occur in the vineyard. When the grapes are used for winemaking, it is also known as viniculture...

, the yield is a measure of the amount of grape

Grape

A grape is a non-climacteric fruit, specifically a berry, that grows on the perennial and deciduous woody vines of the genus Vitis. Grapes can be eaten raw or they can be used for making jam, juice, jelly, vinegar, wine, grape seed extracts, raisins, molasses and grape seed oil. Grapes are also...

s or wine

Wine

Wine is an alcoholic beverage, made of fermented fruit juice, usually from grapes. The natural chemical balance of grapes lets them ferment without the addition of sugars, acids, enzymes, or other nutrients. Grape wine is produced by fermenting crushed grapes using various types of yeast. Yeast...

 that is produced per unit surface of vineyard

Vineyard

A vineyard is a plantation of grape-bearing vines, grown mainly for winemaking, but also raisins, table grapes and non-alcoholic grape juice...

, and is therefore a type of crop yield

Crop yield

In agriculture, crop yield is not only a measure of the yield of cereal per unit area of land under cultivation, yield is also the seed generation of the plant itself...

. Two different types of yield measures are commonly used, mass of grapes per vineyard surface, or volume of wine per vineyard surface.

The yield is often seen as a quality factor, with lower yields associated with wines with more concentrated flavours, and the maximum allowed yield is therefore regulated for many wine appellation

Appellation

An appellation is a legally defined and protected geographical indication used to identify where the grapes for a wine were grown; other types of food often have appellations as well...

s.

Units and conversions

In most of Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, yield is measured in hectoliter per hectare

Hectare

The hectare is a metric unit of area defined as 10,000 square metres , and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metres and the hectare was thus 100 ares or 1/100 km2...

, i.e., by the volume of wine. In most of the New World

New World

The New World is one of the names used for the Western Hemisphere, specifically America and sometimes Oceania . The term originated in the late 15th century, when America had been recently discovered by European explorers, expanding the geographical horizon of the people of the European middle...

, yield is measured in ton

Ton

The ton is a unit of measure. It has a long history and has acquired a number of meanings and uses over the years. It is used principally as a unit of weight, and as a unit of volume. It can also be used as a measure of energy, for truck classification, or as a colloquial term.It is derived from...

 per acres (TPA), i.e., by mass of grapes. Measures in ton or kilogram per hectare are also seen.

Due to differing winemaking

Winemaking

Winemaking, or vinification, is the production of wine, starting with selection of the grapes or other produce and ending with bottling the finished wine. Although most wine is made from grapes, it may also be made from other fruit or non-toxic plant material...

 procedures for different styles of wine, and different properties of different grape varieties, the amount of wine produced from a unit mass of grapes varies. It is therefore not possible to make an exact conversion between these units. Representative figures for the amount of grapes needed for 100 l (1 hl) of wine are 160 kg for white wine, 130 kg for red wine, and 140 kg for a mixture of red and white wine.

Thus:

• for white wine, 100 hl/ha ≈ 16,000 kg/ha (16 ton/ha) = 6.5 ton/acre.
  • 1 ton/acre = 2470 kg/ha ≈ 15 hl/ha
• for red wine, 100 hl/ha ≈ 13,000 kg/ha (13 ton/ha) = 5.3 ton/acre.
  • 1 ton/acre = 2470 kg/ha ≈ 19 hl/ha
• for mixed wine, 100 hl/ha ≈ 14,000 kg/ha (14 ton/ha) = 5.7 ton/acre.
  • 1 ton/acre = 2470 kg/ha ≈ 17.5 hl/ha

Typical yields

Yields vary greatly between countries, regions and individual vineyards, and can be vintage-dependent. Somewhere around 50 hectoliter per hectare, or 3 tons per acre, is a typical representative figure for many countries and regions.

Yields in selected wine-producing countries in 2007 as national averages
Country	Yield (hl/ha)	Vineyard area (1,000 ha)	Wine production (million hl)
Italy Italian wine Italian wine is wine produced in Italy, a country which is home to some of the oldest wine-producing regions in the world. Italy is the world's largest wine producer, responsible for approximately one-fifth of world wine production in 2005. Italian wine is exported largely around the world and has...	55	840	45.9
France French wine French wine is produced in several regions throughout France, in quantities between 50 and 60 million hectolitres per year, or 7–8 billion bottles. France has the world's second-largest total vineyard area, behind Spain, and is in the position of being the world's largest wine producer...	52	867	45.4
Spain Spanish wine Spanish wines are wines produced in the southwestern European country of Spain. Located on the Iberian Peninsula, Spain has over 2.9 million acres planted—making it the most widely planted wine producing nation but it is the third largest producer of wine in the world, the largest...	30	1169	34.7
United States American wine American wine has been produced for over 300 years. Today, wine production is undertaken in all fifty states, with California producing 89 percent of all US wine...	49	409	20
Argentine Argentine wine The Argentine wine industry is the fifth largest producer of wine in the world. Argentine wine, as with some aspects of Argentine cuisine, has its roots in Spain...	65	230	15
Germany German wine German wine is primarily produced in the west of Germany, along the river Rhine and its tributaries, with the oldest plantations going back to the Roman era. Approximately 60 percent of the German wine production is situated in the federal state of Rhineland-Palatinate, where 6 of the 13 regions ...	103	102	10.5
South Africa South African wine South African wine has a history dating back to 1659, and at one time Constantia was considered one of the greatest wines in the world. Access to international markets has unleashed a burst of new energy and new investment. Production is concentrated around Cape Town, with major vineyard and...	73	135	9.8
Australia Australian wine The Australian Wine Industry is the fourth largest exporter of wine around the world, with 760 million litres a year to a large international export market and contributes $5.5 billion per annum to the nation's economy...	55	174	9.6
Portugal Portuguese wine Portuguese wine is the result of traditions introduced to the region by ancient civilizations, such as the Phoenicians, Carthaginians, Greeks, and mostly the Romans. Portugal started to export its wines to Rome during the Roman Empire. Modern exports developed with trade to England after the...	73	248	5.8
Austria Austrian wine Austrian wines are mostly dry white wines with some luscious dessert wines made around the Neusiedler See. About 30% of the wines are red, made from Blaufränkisch , Pinot Noir and locally bred varieties such as Zweigelt...	52	50	2.6

Yield as an indication of quality

While yield is generally seen as an important quality factor in wine production, there are differing views on e.g. the relative importance of low yields to other aspects of vineyard management. In general, there is consensus that if vines are cropped with a very high amount of grape clusters, a poor wine will result because of slow and insufficient ripening of the grapes, due to an unfavourable leaf to fruit ratio. This is a situation that would typically correspond to yields of, say, 200 hl/ha or more, depending on grape variety and many other factors. Beyond that, there are differing schools of thought. One school of thought, generally subscribed to in France, claims that great red wine is impossible to produce at yields exceeding 50 hl/ha. Another school of thought claims that a yield of 100 hl/ha is possible to combine with high quality, provided that careful canopy management is used. In general, white wine is seen as less sensitive to high yields, and some grape varieties, such as Pinot Noir

Pinot Noir

Pinot noir is a black wine grape variety of the species Vitis vinifera. The name may also refer to wines created predominantly from Pinot noir grapes...

, as particularly sensitive to overcropping.

Many examples exist where a vintage-to-vintage variation of yields is in fact positively related with quality, since the low yields can be due to loss of grapes due to adverse conditions such as hail

Hail

Hail is a form of solid precipitation. It consists of balls or irregular lumps of ice, each of which is referred to as a hail stone. Hail stones on Earth consist mostly of water ice and measure between and in diameter, with the larger stones coming from severe thunderstorms...

 or grey rot. For the Bordeaux

Bordeaux wine

A Bordeaux wine is any wine produced in the Bordeaux region of France. Average vintages produce over 700 million bottles of Bordeaux wine, ranging from large quantities of everyday table wine, to some of the most expensive and prestigious wines in the world...

 vintages of the 1980s, it is generally recognised that the best vintages also gave the most abundant harvests.

Regulation of yields

In both France and Italy, the maximum allowed yields are regulated in wine law

Wine law

Wine laws are legislation regulating various aspects of production and sales of wine. The purpose of wine laws includes combating wine fraud, by means of regulated protected designations of origin, labelling practices and classification of wine, as well as regulating allowed additives and...

s, and vary between appellations.

In France, the maximum yields is given in the regulations for each appellation d'origine contrôlée

Appellation d'Origine Contrôlée

Appellation d’origine contrôlée , which translates as "controlled designation of origin", is the French certification granted to certain French geographical indications for wines, cheeses, butters, and other agricultural products, all under the auspices of the government bureau Institut National...

(AOC). The maximum allowed yield for given AOC in a given vintage is a combination of the base yield of the AOC, as modified by the plafond limite de classement (PLC), which is percentage set for each vintage. In most vintages, the PLC allows a production around 20 per cent above the base yield.