Farmers in the United States are familiar with the acre as a measurement of land. An acre was defined back in the middle Ages as the amount of land that could be ploughed in one day with a yoke of oxen. It is 0.0015625 square miles, 4,840 square yards, or 43,560 square feet. In other words, it’s a little smaller than a football field.

A hectare is a metric area equal to 100 square meters. A hectare contains about 2.47 acres, or an acre is about 40 percent the size of a hectare. In the U.S., yields are described as tons per acre. Most vineyards produce on average between 2 and 10 tons of grapes per acre.

Generally speaking, a ton of grapes can produce enough wine to fill a little more than two standard barrels. Howbeit, note that this usually depends on the kind of grapes, the skin-to-seed-to-juice ratio, and things like weather (rain just before harvest will add to the liquid content of the grapes), as well as the method of making red wine vs. white wine.

Let’s imagine that 1 ton of grapes are a little more than two barrels, and each barrel contains about 60 gallons, which translates to 25 cases, or 300 bottles. Therefore, 1 ton of grapes yield about 63 cases, or 756 bottles. A low – yielding 1 – acre vineyard that yields 2 tons of grapes makes about 120 cases, or 1,440 bottles, while an acre that yields 10 tons produces about 600 cases, or 7,200 bottles.

If we take this back to the more acceptable metric system, yields are measured in hectolitre (100 litters) per hectare. One ton per acre is about 17.5 hectolitres per hectare, and most vineyards produce between 35 and 175 hectolitres per hectare.

However, assuming we still concur with the above estimate that 1 ton is a little more than two barrels, and 1 acre is .404686 hectares, and vineyards yield between two and 5 tons per acre, the range of yield per hectare is 296 to 1,482 cases, or 3,558 to 17,791 bottles.

In the United States, there are really a lot of variables that will affect what’s known as a vineyard’s “yield.” Not just the types of grapes, but how far apart the vines are spaced, how old the grapevines are, below are some of the factors that will influence the amount of yield a Vineyard produces.

5 Factors That Determine How Many Cases of Wine Bottle You Get Per Acre of Vineyard?

  1. The Plant’s Environment

Have it in mind that factors like climate, weather and soil affect the quantity and quality of the fruit. Heat is very crucial: the plant uses sunlight and chlorophyll to produce the glucose it needs for growth and vigour by combining CO2 and water. In clearer terms, the goal of viticulture practices is to concentrate the glucose in the fruit, not just in the vine. Left to its own devices, the plant will use all available resources to grow stronger and bigger.

a. Climate and Weather

It is very imperative to differentiate climate and weather: Climate refers to the average weather characteristics over a period of several years. The changes produced in these characteristics constitute the weather. The different types of weather include;

  • Continental: Areas located away from large bodies of water. Significant difference in temperature between the hottest and coldest months of the year. Short, warm and dry summers. Cold, severe winters.
  • Maritime: Very little difference in temperature between the warmer and colder months of the year. Rainfall is distributed throughout the year, which has a moderating effect on temperature.
  • Mediterranean: the characteristics of the Mediterranean climate are very similar to those of maritime climates, except that summers are hotter and drier.

b. Temperature

Have it in mind that during its growth cycle, the vine requires an average temperature of 16 to 22ºC to undergo photosynthesis. Also, different varieties need different amounts of heat to reach optimal ripeness. In the wine world, the temperature scale is categorized as follows:

  • Cool: Regions with an average temperature equal to or below 17ºC during the plant’s growth cycle.  Ideal for short – cycle varieties.
  • Mild: Regions with an average temperature of 17 to 18.5º
  • Warm: Average temperature of 18.5 to 21º Ideal for long – cycle varieties.
  • Hot: Temperatures above 21º These regions are not the most suitable for winegrowing.

c. Sunlight

Note that the amount of light absorbed by the plant determines the rate of photosynthesis. In other words, the more light there is the more glucose the plant produces. Also note that excessive sunlight exposure can also be harmful: the skin of the grapes can burn, resulting in a bitter flavour that affects the quality of the wine.

d. Soil

Have it in mind that vine grows in soil that consists of differently sized rock particles, humus (decomposing organic matter) and nutrients. The best winegrowing soil is nutrient poor, well drained and capable of storing the amount of water the plant needs to grow.

Good soil should also have the capacity to store sufficient amounts of water at the beginning of the plant’s growth cycle to make sure it gets a strong start. In the summer, the plants are subjected to slight levels of water stress after veraison to encourage ripening.

The best soil for vine should also contain small quantities of certain basic nutrients: nitrogen, phosphorus and potassium. If the nutrient levels are very high, the plant grows too vigorously, resulting in an excessively dense canopy. This would prevent sunlight from reaching the grapes and impede their ripening.

  1. Species and Varieties

In the United States, there are more than sixty different species of grape. Vitis Vinifera, however, is the only one used for winemaking. Other species (Vitis Riparia, V. Rupestris, V. Berlandieri) originating from North America are used as rootstocks, because they are immune to phylloxera.

Although now under control, the pest is still a concern to this day. However, from a layperson’s point of view, the way grapevines are grown and reproduce is quite odd. For instance, if a seed is planted —a Cabernet Sauvignon pip—the resulting plant would NOT be Cabernet.

However, to propagate a variety, you have to take cuttings from an existing plant which, in turn, derives from a single “mother” plant. Note that varieties that have managed to thrive in different parts of the world are known as international varieties: Cabernet, Merlot, Syrah, Pinot Noir, Chardonnay, and Sauvignon Blanc.

  1. Viticultural Practices

Note that if the winegrower fails to intervene, the plant would direct all of its resources to growing freely. The resulting fruit would be sufficiently ripe to attract birds, but not to make wine. So to control the plant, a few musts to remember include:

  • Training and trellising: Have it in mind that these systems determine the direction in which the shoots will grow. The positioning of the vines follows the selected trellising system. This simply refers to the system of posts and wires that are seen in vineyards, which support the vine shoots.
  • Pruning: Pruning is used to limit the size of the vine and control yields by eliminating canes and leaves. Note that the goal is to set the number of buds that will subsequently grow out and produce fruit.
  • Canopy management: This involves limiting canopy growth by removing leaves and vine shoots to direct glucose production toward the fruit. It also allows us to increase and improve the fruit’s sunlight exposure.
  1. The Harvest

In the wine making process, harvest begins once the winegrower and the enologist decide that the grapes have reached the perfect balance between sugar levels and physiological maturity. Note that sometimes the harvest has to be brought forward to avoid threatening weather conditions. Hail can damage the grapes whereas excessive rainfall fills the berries with water, thus diluting the sugar and affecting the quality of the subsequent wine.

  • Mechanical harvest: Speed is the primary advantage of mechanical harvesting. This is mainly advantageous under bad weather conditions in order to avoid oxidation and premature fermentation. Additionally, it allows for night – time harvesting, which delivers the grapes to the winery at a lower temperature.

This simply entails that wineries save energy, because the grapes don’t have to be chilled prior to fermentation. Mechanical harvesting, however, does not allow for selective grape – picking and collects undesirable grapes, insects, leaves and more along the way.

  • Manual harvest: note that manual harvesting is slower and demands a bigger workforce, but allows pickers to select the grapes. Additionally, the whole – cluster harvesting reduces the risk of damage to the fruit. Manual harvests can be used in all kinds of terrain. Notably, in vineyards located on steep hillsides, manual harvesting is the only option (Mosel, Douro, and Northern Rhône.)
  1. Enological Practices

Oxygen management, sulphur dioxide use and oak influence are common elements in the processes of vinification and aging.

a. Oxygen, Sulphur Dioxide and Oak

Note that oxygen is a highly reactive gas, which simply means that when it combines with other molecules, it alters their properties. With that in mind, oxygen oxidizes wine; its proper management is imperative during vinification and aging in order to obtain the desired result. If for instance you are looking to preserve varietal aromas then oxygen should be avoided at all cost. Remember: as wine oxidizes, it loses its fruit aromas.

To avoid this, the grapes are kept cool until reaching the winery, because low temperatures slow down the chemical reactions; in addition, winemakers use antioxidants like sulphur dioxide, which also acts as an antiseptic. An absolute must in a winery. During aging, it is very necessary to control the amount of oxygen that enters through the oak, which is permeable.

The level of oxidation depends on the size of the barrel, the length of time the wine remains in the barrel and whether it is full or not. Note that in these types of wine, oxidation develops and adds aromatic complexity. Therefore, the wines become more flavourful and earthy. In red wines, it softens the tannins and stabilizes colour.

Owing to the fact that the factors mentioned above can alter a vineyard’s yard, 1 acre of vines will more or less produce 3 to 5 tons of grapes. Each ton of grapes produces 150 gallons of wine. A normal bottle of wine is 750 ml.

So, a case of 12 bottles totals 9 liters or roughly 2.4 gallons. At 150 gallons per ton, you’ll produce 63 cases of wine per ton, or 756 bottles per ton. Producing 3 to 5 tons of grapes per acre pans out to be 190 to 315 cases of bottled wine per acre.

Solomon. O'Chucks
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