Question regarding productivity of a vineyard?

In the US the productivity of a vineyard is expressed as weight of the fruit per unit measure of area (tons/acre).

In Europe and other countries that mainly use the metric system the productivity of a vineyard is expressed as a unit of volume per unit measure of area (HL/Ha).

What does this unit measure of volume actually measure? Volume of finished wine? Volume of juice in must? For white wine production this expression makes sense. But for red wine production, the volume of the finished wine is almost always greater than the volume of the juice in the must (the grape solids are pressed after fermentation). Depending upon pressure and duration this volume can be significant. Besides it is very likely that the lightly pressed wine would most definitely be added to the main batch of wine, and if the winemaker desires to add more complexity to the evolving wine the “second pressed” or a portion of it will also be added to the main batch of evolving wine.

Salute

According to the following link, the hectoliters is finished wine, not juice or must.

http://www.epicurious.com/drinking/wine ... ry?id=8587

Another thing to keep in mind is that hl/ha is based on a horizontal plane. I'm always getting into discussions about German vineyards (which are FAR from horizontal) and they're relatively high production figures on paper. One must be reminded that measured in a plane, most vines would overlap thus giving higher yeild fiqures than the hectare actually produces. This obviously goes for all steeply inclined vineyards the world over.

Prost!
Bill

Thanks for responding Howie and Bill.

Salute

Even before I read Bill's note about the horizontal plane, I thought measures of yield were rubbish. Between close-plant/hand-picked and machine-managed vineyards, the number of vines per acre/hectare is so variable that all these measures are useless, in my opinion. Kilograms of grapes per vine. That's what the measure should be. kg/v. A uniform measure. And it would soon prove that a lot of new world 'low yielding vineyards' are no such thing...
cheers,
Graeme

Even before I read Bill's note about the horizontal plane, I thought measures of yield were rubbish. Between close-plant/hand-picked and machine-managed vineyards, the number of vines per acre/hectare is so variable that all these measures are useless, in my opinion. Kilograms of grapes per vine. That's what the measure should be. kg/v. A uniform measure. And it would soon prove that a lot of new world 'low yielding vineyards' are no such thing...
cheers,
Graeme

I'm not sure I understand your point. In a given area a certain amount of grapes are produced. Likewise, in a given area, a certain amount of sunlight is available to photosynthesize light collected by the leaves into sugar in the grapes. One can produce lots of grapes with little sugar or few grapes with lots of sugar by such things as cluster thinning and canopy management. Whether one has lots of vines in a given area or few vines is not as critical as the ability of each vine to be properly exposed to enough sunlight to properly ripen the grapes.

Even before I read Bill's note about the horizontal plane, I thought measures of yield were rubbish. Between close-plant/hand-picked and machine-managed vineyards, the number of vines per acre/hectare is so variable that all these measures are useless, in my opinion. Kilograms of grapes per vine. That's what the measure should be. kg/v. A uniform measure. And it would soon prove that a lot of new world 'low yielding vineyards' are no such thing...
cheers,
Graeme

I'm not sure I understand your point. In a given area a certain amount of grapes are produced. Likewise, in a given area, a certain amount of sunlight is available to photosynthesize light collected by the leaves into sugar in the grapes. One can produce lots of grapes with little sugar or few grapes with lots of sugar by such things as cluster thinning and canopy management. Whether one has lots of vines in a given area or few vines is not as critical as the ability of each vine to be properly exposed to enough sunlight to properly ripen the grapes.

OK, I understand how the difference between 9000 vines per acre and 11000 vines per acres fits into your 'diagram' - you increase the vines, yield per vine decreases, they block each other's sunshine, hl/ha is unchanged etc. But once you get to New World levels - 2500 vines / hectare with plenty of space to drive a big tractor and grape harvester between the rows - to claim you're only cropping at 1.5 tonnes / acre (and therefore matching Grand Cru levels or whatever) is plain deceptive. You could double your vines (and gross yield) without affecting in any way the ripeness of the existing grapes. But you couldn't use your normal farm tractor anymore...
cheers,
Graeme

Now I see your point. However, I have a different proposal. Your proposal of measuring the weight of grapes per vine is still lacking. Instead, it should be 3 dimensional - amount of sugar in a given volume of juice produced in a given area.

This is an interesting debate. Richard Smart's examples in Sunlight into Wine (and a more recent article in the Wine Business Monthly) suggest that there is no direct relationship between yield and quality, ie that better farming methods can trump yield in some situations.

This reminds me of a few ways that one can determine what the optimum ripeness level for a particular vineyard site. According to Dr. Yair Margaalit in his book “Winery Technology & Operations- A Handbook for Small Wineries”, one method is based upon the product of the following equation: weight of a certain and constant number of berries (any weight unit) X (times) the average Brix of those berries. The result of this equation can be plotted vs. time and one can predict the optimum ripeness level and determine when the best time to harvest is. During ripening period (for most grape varieties), both the sugar and water content increase per berry, at maturity, the sugar accumulation slows down considerably and the water content begins to decline. Also there is UC Davis suggestion when the Brix to TA (Total Acidity) ratio reaches or approaches 30:1 or 35:1, its time to harvest. Jeff Cox in his book “From Vines to Wines” gives us another option Brix X pH 2, for white grapes when this number approaches 200 the grapes can be harvested; for red grapes when this number approaches 260 the grapes can be harvested. All three methods (as Howie pointed out) is based on sugar accumulation in the juice.

Salute