The debate over whether or not moderate wine consumption is a beneficial or a detrimental thing continues. I suppose it will never end, but here is the latest campaign by some people who are against it.
An article published in The Age, from Melbourne in Australia, "Experts see red over wine 'myth'," details the new push by the Alcohol Policy Coalition to discourage the consumption of alcohol.
The Alcohol Policy Coalition is an Australian group made up of the Australian Drug Foundation, Cancer Council Victoria, Heart Foundation, Turning Point Alcohol and Drug Centre and VicHealth, who share "concern relating to the misuse of alcohol and its health/social impacts on the community."
The "report" they refer to in their press release is really a press release, also, or in their words, a "position statement," so not a report at all. In it, they summarise some information relating to alcohol consumption and its association with non-communicable diseases.
My main concern about this statement is that they use data that result from the misuse of alcohol to support their statements such as, "Every drinking occasion contributes to the life-time risk of harm from
alcohol, therefore, any reduction in the dose - that is the amount and
frequency of alcohol consumed - will reduce the annual and life-time risk of alcohol related harm."
This is an unsubstantiated remark and of no relation to the information they have presented.
In paragraph two of the statement they say this:
"In 2008, alcohol misuse was responsible for 2.3 million deaths (3.8 per cent) globally."
This is fair enough, however, the key word there is "misuse."
I would hope that the vast majority of people do not misuse alcohol, meaning they have chronic and excessive consumption. It is also worth noting that in the report they cite as the source of the information (World Health Organization Global status report on noncommunicable diseases 2010) that 80% of the deaths are in low to middle-income countries, and therefore only 20% in the high-income countries.
Per capita consumption of alcohol is listed in the WHO report and low-income countries have a value of about 4 litres per capita and high-income at just over 10 litres per capita. Since the consumption level is lower in the countries that have the highest percentage of deaths due to alcohol, I read this as meaning that binge drinking and other forms of alcohol abuse are the reason why so many people are dying there. With more affluent societies, alcohol (and wine in particular) is consumed more regularly, but also more responsibly.
So I'm not convinced by their argument that we should increase taxes on alcohol in places like New Zealand, Australia, or other higher-income countries. The real problem seems to be in other places, where perhaps more control over people's access to alcohol is warranted, or better yet, the institution of policies that educate about alcohol use.
The other thing that I am always cautious about with studies relating to alcohol consumption and disease incidence is whether or not it is a cause and effect, or if the disease incidence change is due to other factors that are associated with alcohol consumption. We've already mentioned that higher income countries have more alcohol consumption, so you can draw relationships between such things as the number of television sets per household in a country and the level of alcohol consumption. So does that mean that to curb alcohol consumption we should limit the number of televisions?
A bit of an absurd example, but it makes the point - sometimes you can get correlations between factors, but they are not direct cause and effect. You need to look at the information and see exactly what it is they're testing, and make sure that they do have evidence that backs up their claims.
I, personally, am an advocate of moderate wine consumption. However, this is not from the health point of view, but mostly because I find it a fascinating beverage, and that it accompanies food so well. I would never recommend to anyone to start drinking wine because it will make you healthier, but I would recommend people try it and see if they like it.
What I'm not keen on is a tax-grab on alcohol, and wine in particular, under the pretext that we are being saved from ourselves.
Monday, September 19, 2011
Monday, September 12, 2011
New Zealand should concentrate on red wine more than it does. Plus, the secret menace!
Master of Wine Steve Smith, who is also the Director of Wine and Viticulture at Craggy Range in Hawkes Bay, was recently in the news saying that New Zealand should stop for a moment and concentrate on making its reds even better, rather than going off on all these new "fashion" varieties making the rounds (Grüner Veltliner, anyone??).
There's a lot of merit to that sentiment -New Zealand can do great reds, starting with Pinot noirs, Merlots, Syrahs and even overlooked varieties such as Malbec. As well as his mention of Craggy Range and Felton Road, some other noteworthy producers of reds in Aotearoa are Fromm Estate, Forrest Estate, Mount Difficulty, Millton Vineyard, Kumeu River, Te Mata Estate and a host of others on Waiheke Island. And in one fell swoop, I have left out loads of other wineries that produce great tasting reds on a consistent basis...
It will take more work in the vineyard to get this right, starting from the beginnings of site selection and all the rest that goes after it. But done right, and in suitable places, it should be possible to consistently produce great quality reds right here in our little patch of land in the Pacific Ocean.
Let's go to it, guys!!
However, Steve Smith also lets loose a huge cannonball, which is probably the one that should be making headlines in the eyes of viticulturists in New Zealand:
It's primary means of spread is via mealybugs or less often, scale insects. The habitat range of mealybug in particular is spreading, and so goes Leafroll Viruses with it.
So far, there is no way to cure infected vines, so control is limited to pulling out infected vines (and often the neighboring vines as well), planting with virus-free stock, and trying to prevent the mealybug vectors from coming in again.
The latter point will be crucial for eventual effective management of the disease - much more research into how the virus and its vector(s) can be controlled is needed, and here in New Zealand conditions - we can't rely on overseas work alone.
Here's hoping that some virologists and entomologists out there and eager to take up the challenge!!
There's a lot of merit to that sentiment -New Zealand can do great reds, starting with Pinot noirs, Merlots, Syrahs and even overlooked varieties such as Malbec. As well as his mention of Craggy Range and Felton Road, some other noteworthy producers of reds in Aotearoa are Fromm Estate, Forrest Estate, Mount Difficulty, Millton Vineyard, Kumeu River, Te Mata Estate and a host of others on Waiheke Island. And in one fell swoop, I have left out loads of other wineries that produce great tasting reds on a consistent basis...
It will take more work in the vineyard to get this right, starting from the beginnings of site selection and all the rest that goes after it. But done right, and in suitable places, it should be possible to consistently produce great quality reds right here in our little patch of land in the Pacific Ocean.
Let's go to it, guys!!
However, Steve Smith also lets loose a huge cannonball, which is probably the one that should be making headlines in the eyes of viticulturists in New Zealand:
Grapevine Leafroll associated Viruses, in particular, the Type 3 variant, are insidious beasts, which are working their way through our vines - slowly, but surely becoming something that we will have to manage much more actively in the near future."This year would be the last for the Les Beaux Cailloux [one of their best Chardonnays, ed.] due to the onset of leaf roll virus which is threatening to spread to neighbouring vines with red grapes."
It's primary means of spread is via mealybugs or less often, scale insects. The habitat range of mealybug in particular is spreading, and so goes Leafroll Viruses with it.
So far, there is no way to cure infected vines, so control is limited to pulling out infected vines (and often the neighboring vines as well), planting with virus-free stock, and trying to prevent the mealybug vectors from coming in again.
The latter point will be crucial for eventual effective management of the disease - much more research into how the virus and its vector(s) can be controlled is needed, and here in New Zealand conditions - we can't rely on overseas work alone.
Here's hoping that some virologists and entomologists out there and eager to take up the challenge!!
Monday, August 8, 2011
Things that change fruit ripening
I've talked about fruit thinning before, and here's another missive.
Common in commercial practice is to do thinning at colour change, so that you can remove the fruit that is less-advanced in ripening - i.e. the stuff that hasn't gone through veraison as soon as the bulk of it.
When you do this, you're advancing the maturty of the harvested fruit. However, this is only so because you have removed that tail end of the fruit -all the stuff that's less ripe, so that the average brix is higher, and that carries on through to harvest.
But, what if you remove fruit randomly at that point in the season? I don't believe you will see much of an effect on Brix at harvest, if at all.
I think this is because regardless of how much fruit is on the vine (within reason!), the rate at which it will accumulate brix won't change much. The conduit for the sugars to pass through is the phloem, and under the conditions in the vine during ripening, sugars are already moving through and into the berry as fast as they can. Removing fruit might mean the vine has more carbohydrates available, but that doesn't mean that the pipes (phloem) leading to the berries can push more sugar into the berry. There is a limit!
In fact, there is evidence that the size of fruit is related to the diameter of the stem that leads to that fruit (i.e. a larger number of pipes leads to a larger fruit), such as this paper working with citrus. This doesn't necessarily mean cause and effect, but it is a logical conclusion.
It might also mean that if you think the fruit early enough (within a couple of weeks post-fruit set), you might be able to enhance the ripening of the fruit because the pedicels can grow larger due to the greater amount of carbohydrate available? I wish I knew the answer to that question!!
When you do this, you're advancing the maturty of the harvested fruit. However, this is only so because you have removed that tail end of the fruit -all the stuff that's less ripe, so that the average brix is higher, and that carries on through to harvest.
But, what if you remove fruit randomly at that point in the season? I don't believe you will see much of an effect on Brix at harvest, if at all.
I think this is because regardless of how much fruit is on the vine (within reason!), the rate at which it will accumulate brix won't change much. The conduit for the sugars to pass through is the phloem, and under the conditions in the vine during ripening, sugars are already moving through and into the berry as fast as they can. Removing fruit might mean the vine has more carbohydrates available, but that doesn't mean that the pipes (phloem) leading to the berries can push more sugar into the berry. There is a limit!
In fact, there is evidence that the size of fruit is related to the diameter of the stem that leads to that fruit (i.e. a larger number of pipes leads to a larger fruit), such as this paper working with citrus. This doesn't necessarily mean cause and effect, but it is a logical conclusion.
It might also mean that if you think the fruit early enough (within a couple of weeks post-fruit set), you might be able to enhance the ripening of the fruit because the pedicels can grow larger due to the greater amount of carbohydrate available? I wish I knew the answer to that question!!
Wednesday, May 18, 2011
Water footprints - another eco-measure
Radio New Zealand had an article about water footprints a while ago, which stated that 109 litres of water is used to produce the average glass (125ml) of wine (see the article that prompted it all here). This is not the first time this has been in the news - I found this article in the Economist from back in Feb 2009 and a column from The Wine Economist from late 2008, which cites a special issue (December 2008) of the Wine Business Monthly on the topic...
Water use is a hot topic, both in terms of how much is used, but also what to do with the water afterwards. In fact, there is an internationally focussed meeting about this, specifically aimed at the wine industry, being held in Blenheim later this year (6th International Specialised Conference on Sustainable Viticulture: Winery Waste and Ecologic Impacts Management)
The Radio NZ article was brief, and I didn't hear the audio version of it, but I was intrigued, as figures like this are hard to interpret without knowing what goes into calculating it. So I wrote to Dr. Ranvir Singh, who is a Senior Lecturer in Environmental Hydrology and Soil Science at the Institute Of Natural Resources, Massey University to see if more information was available.
He very kindly replied and pointed me toward reports from the Water Footprint Network, who have published reports on global average values for water "use" for various crops and for animal farming. They were also the organisation behind the 2009 article, which quoted the values as coming from a report by Peter Gleick, who got his data (Table 19) from Waterfootprint.org.
So what is a water footprint? From the Water Footprint Network, it is "a spatially and temporally explicit indicator of direct and indirect water use of consumers and producers."
What does this mean? Similar in concept to the Ecological Footprint, and its sub-category the Carbon Footprint, the Water Footprint attempts to track all actual and "virtual" water use in the production and life of a item.
It's pretty easy to calculate the amount of water that is applied to grapevines, for example, and then set that against the tonnage of grapes harvested and the amount of wine subsequently made. And it's also reasonably straightforward to estimate the amount of water used in the winery through processing of the grapes into wine. There's even the opportunity to take into account the water used in the production of the labels, corks/caps, cardboard boxes etc. and add that to the total.
However, what is virtual water? Well gracious me, Wikipedia has an entry on that, too! The definition they quote there is “the volume of freshwater used to produce the product, measured at the place where the product was actually produced”
Getting back to our 109L per glass, that equates to about 870L of water per litre of wine. Let's look at what the vine contributes to that total.
Grapevines can typically use a couple of litres of water per day during the peak of the growing season, but use less in the Spring and Autumn as the temperatures decrease. So to allow some fudge-factor room, figure maybe 5 months of using 2L per day on average (either water in the soil or water applied through rain or irrigation). That's about 360L per season for the vine.
The amount of fruit a vine will produce varies a lot, but if we look at a typical Sauvignon blanc vine it might produce 4.5kg of fruit (this value varies a lot with vine spacing and other factors, but let's keep it simple...). In the winery this will probably equate to almost 3 litres of juice, which most likely will turn into about 2.9L of wine. So the vine itself is using about 124L of water to produce a litre of wine.
So that's about 14% of the total suggested by the report. The other 76% must come about from the winemaking process, packaging and other items used during the growing of the grapes and production of the wine.
However, some studies suggest that daily vine water usage can be upwards of 60 litres per day (e.g. here)! Yes, this is not the average over a season, but in a dry area with vines having a high crop load, the daily average might be quite a bit higher. All of a sudden, the vine is contributing a lot more to the total virtual water use, maybe doubling, tripling the value, or even more.
So what should we make of all this? With any model system, such as what they are doing with the water use studies, there are a lot of assumptions that need to be made - if there weren't the models would be far too complex to actually use. We've demonstrated with relatively simple calculations that there can be wide variation in the final number depending on the numbers going in.
So taking a value you might hear somewhere doesn't really mean an awful lot until you start investigating what went into the calculation of that number, and understanding how it comes about.
That is, with thy wine, take a grain of salt.... :-)
Here are some links of potential interest on the topic of water use:
Sonoma Wine Company, Graton Facility - A winery that was successful in reducing their water use
New Recycling Technology Turns Winery into Water Saver
A winery re-using water that has come from the winery
Wine Business Monthly article on winery water use
Sustainable Farming Fund project looking at benchmarking water use in the vineyard
Water use efficiency of table and wine grapes in Western Cape
Water use is a hot topic, both in terms of how much is used, but also what to do with the water afterwards. In fact, there is an internationally focussed meeting about this, specifically aimed at the wine industry, being held in Blenheim later this year (6th International Specialised Conference on Sustainable Viticulture: Winery Waste and Ecologic Impacts Management)
The Radio NZ article was brief, and I didn't hear the audio version of it, but I was intrigued, as figures like this are hard to interpret without knowing what goes into calculating it. So I wrote to Dr. Ranvir Singh, who is a Senior Lecturer in Environmental Hydrology and Soil Science at the Institute Of Natural Resources, Massey University to see if more information was available.
He very kindly replied and pointed me toward reports from the Water Footprint Network, who have published reports on global average values for water "use" for various crops and for animal farming. They were also the organisation behind the 2009 article, which quoted the values as coming from a report by Peter Gleick, who got his data (Table 19) from Waterfootprint.org.
So what is a water footprint? From the Water Footprint Network, it is "a spatially and temporally explicit indicator of direct and indirect water use of consumers and producers."
What does this mean? Similar in concept to the Ecological Footprint, and its sub-category the Carbon Footprint, the Water Footprint attempts to track all actual and "virtual" water use in the production and life of a item.
It's pretty easy to calculate the amount of water that is applied to grapevines, for example, and then set that against the tonnage of grapes harvested and the amount of wine subsequently made. And it's also reasonably straightforward to estimate the amount of water used in the winery through processing of the grapes into wine. There's even the opportunity to take into account the water used in the production of the labels, corks/caps, cardboard boxes etc. and add that to the total.
However, what is virtual water? Well gracious me, Wikipedia has an entry on that, too! The definition they quote there is “the volume of freshwater used to produce the product, measured at the place where the product was actually produced”
Getting back to our 109L per glass, that equates to about 870L of water per litre of wine. Let's look at what the vine contributes to that total.
Grapevines can typically use a couple of litres of water per day during the peak of the growing season, but use less in the Spring and Autumn as the temperatures decrease. So to allow some fudge-factor room, figure maybe 5 months of using 2L per day on average (either water in the soil or water applied through rain or irrigation). That's about 360L per season for the vine.
The amount of fruit a vine will produce varies a lot, but if we look at a typical Sauvignon blanc vine it might produce 4.5kg of fruit (this value varies a lot with vine spacing and other factors, but let's keep it simple...). In the winery this will probably equate to almost 3 litres of juice, which most likely will turn into about 2.9L of wine. So the vine itself is using about 124L of water to produce a litre of wine.
So that's about 14% of the total suggested by the report. The other 76% must come about from the winemaking process, packaging and other items used during the growing of the grapes and production of the wine.
Flood irrigation has a low capital cost to install, but is not suited to all areas, and quite a bit of water can be lost to evaporation, rather than getting to the vine roots.
However, some studies suggest that daily vine water usage can be upwards of 60 litres per day (e.g. here)! Yes, this is not the average over a season, but in a dry area with vines having a high crop load, the daily average might be quite a bit higher. All of a sudden, the vine is contributing a lot more to the total virtual water use, maybe doubling, tripling the value, or even more.
In-line drippers deliver the water to vines much more efficiently than flood irrigation
So what should we make of all this? With any model system, such as what they are doing with the water use studies, there are a lot of assumptions that need to be made - if there weren't the models would be far too complex to actually use. We've demonstrated with relatively simple calculations that there can be wide variation in the final number depending on the numbers going in.
So taking a value you might hear somewhere doesn't really mean an awful lot until you start investigating what went into the calculation of that number, and understanding how it comes about.
That is, with thy wine, take a grain of salt.... :-)
Here are some links of potential interest on the topic of water use:
Sonoma Wine Company, Graton Facility - A winery that was successful in reducing their water use
New Recycling Technology Turns Winery into Water Saver
A winery re-using water that has come from the winery
Wine Business Monthly article on winery water use
Sustainable Farming Fund project looking at benchmarking water use in the vineyard
Water use efficiency of table and wine grapes in Western Cape
Monday, May 9, 2011
Frosts in California (and elsewhere!)
I have mentioned frosts before (August 14 and October 17, 2009), but some recent news brings this subject up again.
Early season frost is a big problem in New Zealand, but also in a lot of other growing regions around the world, such as in Ontario, which I've talked about before. The latest news from California, in an article from Western Farm Press, details the aftermath of a couple of frost events on April 8-10 in areas south of San Francisco. Damage estimates suggested that about one-quarter of the 10,500 hectares of grapes in the Paso Robles area will have a crop that won't be commercially worth harvesting.
Any grower worth his weight in quality secateurs should know what the frost risk is when looking to develop a vineyard, and if the risk is perceived as being great enough, some sort of management system will be planned for the development
Results of a severe spring frost - all green tissues of the vine are completely decimated
If the frosts are mild, then passive means, such as having bare soil between the rows in the spring, which will maximise heat accumulation during the day and release at night, can give from 0.5 to 1.0°C protection (of course, careful decision making in site selection is the best means of passive management!).
Active means of management include such things as taking advantage of an inversion layer (where a layer of warm air sits above the cold air at vine level, and which tend to form on still nights with clear skies) and sending up a helicopter to push the warm air down to mix with the cold.
However, if the frosts are very frequent, then installing a permanent system becomes cost effective, such as the wind machines I've already written about, or using water sprinkled over the vines.
A frost fan installed in Central Otago. Plenty of snow-capped mountains around the area!
There are some big differences between the wind and water methods. The movement of air method relies on mixing the warmer air in an inversion layer with the cold air on the ground. This works great unless 1) the inversion layer doesn't have enough warm air to raise the temperature of the cold air to above freezing or 2) there is no inversion layer.
The former is heartbreaking, as you might be successfully fighting off the freezing temperatures, then just before dawn and the temperature rise that comes with it, the inversion layer is all used up and the grape buds freeze.
The latter has the same outcome, but then you don't have to spend all night running around trying to combat the frost!!
In some cases, the conditions are not right for an inversion layer to form, or the cold might be coming in as a mass of freezing air, for example, from nearby hills or mountains that have recently been covered by snow (this appears to be what happened in California recently). In this case, since there is no warm air around, fans and helicopters won't help. However, the application of water to the plants will work for all types of frost events.
The idea behind the application of water is that as water goes from liquid to solid form (freezes) it releases heat (heat of fusion).
So as long as water is freezing on the plants, heat is being released, effectively keeping the temperature at 0°C. Plant tissues can survive this temperature and even a bit lower without damage, so as long as enough water is supplied to always have some in the process of crystallising, the ice, and grape buds or shoots inside, will be kept from temperatures that might damage them.
Two types of post-mounted micro-sprinklers - these use quite a bit less water than the traditional impact-type overhead sprinklers
The down side is that if enough water is not applied, the temperature can continue to decrease, so if the application system breaks, or the water runs out, before the air temperature rises sufficiently, you can lose the new growth.
In the foreground row visible in this picture there is a number of vines where less growth is visible. This is because the sprinkler at the top of the post (centre left in the photo) failed during a frost event, meaning that the vines were not continuously covered with water - thus once the freezing stopped, the temperature of the ice and tissues within dropped to damaging levels. Note that there is a frost fan in the background - the fan isn't able to cover the area that these vines are in, so the sprinklers were put in to provide protection there.
My preference, if I were to plant in an area that was prone to frost events, would be to use water sprinklers. However, in some cases there wouldn't be enough water available for this. Large dams can be build to provide a source of water, but sprinkling even a hectare of ground with water for a decent frost can require up to 40 cubic metres of water per hour depending on the system used!
The concerning thing is that with global changes to climate, we should be prepared for more extreme weather events - in this context, we need to be ready for more severe frosts later in the season. Seeing as how some grape growing regions in New Zealand can have a potentially damaging frost in almost every month of the year (historically, anyway), this isn't good news!!!
Hands up those who thought being a viticulturist was a cushy job!!
Early season frost is a big problem in New Zealand, but also in a lot of other growing regions around the world, such as in Ontario, which I've talked about before. The latest news from California, in an article from Western Farm Press, details the aftermath of a couple of frost events on April 8-10 in areas south of San Francisco. Damage estimates suggested that about one-quarter of the 10,500 hectares of grapes in the Paso Robles area will have a crop that won't be commercially worth harvesting.
Any grower worth his weight in quality secateurs should know what the frost risk is when looking to develop a vineyard, and if the risk is perceived as being great enough, some sort of management system will be planned for the development
Results of a severe spring frost - all green tissues of the vine are completely decimatedIf the frosts are mild, then passive means, such as having bare soil between the rows in the spring, which will maximise heat accumulation during the day and release at night, can give from 0.5 to 1.0°C protection (of course, careful decision making in site selection is the best means of passive management!).
Active means of management include such things as taking advantage of an inversion layer (where a layer of warm air sits above the cold air at vine level, and which tend to form on still nights with clear skies) and sending up a helicopter to push the warm air down to mix with the cold.
However, if the frosts are very frequent, then installing a permanent system becomes cost effective, such as the wind machines I've already written about, or using water sprinkled over the vines.
A frost fan installed in Central Otago. Plenty of snow-capped mountains around the area!There are some big differences between the wind and water methods. The movement of air method relies on mixing the warmer air in an inversion layer with the cold air on the ground. This works great unless 1) the inversion layer doesn't have enough warm air to raise the temperature of the cold air to above freezing or 2) there is no inversion layer.
The former is heartbreaking, as you might be successfully fighting off the freezing temperatures, then just before dawn and the temperature rise that comes with it, the inversion layer is all used up and the grape buds freeze.
The latter has the same outcome, but then you don't have to spend all night running around trying to combat the frost!!
In some cases, the conditions are not right for an inversion layer to form, or the cold might be coming in as a mass of freezing air, for example, from nearby hills or mountains that have recently been covered by snow (this appears to be what happened in California recently). In this case, since there is no warm air around, fans and helicopters won't help. However, the application of water to the plants will work for all types of frost events.
The idea behind the application of water is that as water goes from liquid to solid form (freezes) it releases heat (heat of fusion).
So as long as water is freezing on the plants, heat is being released, effectively keeping the temperature at 0°C. Plant tissues can survive this temperature and even a bit lower without damage, so as long as enough water is supplied to always have some in the process of crystallising, the ice, and grape buds or shoots inside, will be kept from temperatures that might damage them.
Two types of post-mounted micro-sprinklers - these use quite a bit less water than the traditional impact-type overhead sprinklersThe down side is that if enough water is not applied, the temperature can continue to decrease, so if the application system breaks, or the water runs out, before the air temperature rises sufficiently, you can lose the new growth.
In the foreground row visible in this picture there is a number of vines where less growth is visible. This is because the sprinkler at the top of the post (centre left in the photo) failed during a frost event, meaning that the vines were not continuously covered with water - thus once the freezing stopped, the temperature of the ice and tissues within dropped to damaging levels. Note that there is a frost fan in the background - the fan isn't able to cover the area that these vines are in, so the sprinklers were put in to provide protection there.My preference, if I were to plant in an area that was prone to frost events, would be to use water sprinklers. However, in some cases there wouldn't be enough water available for this. Large dams can be build to provide a source of water, but sprinkling even a hectare of ground with water for a decent frost can require up to 40 cubic metres of water per hour depending on the system used!
The concerning thing is that with global changes to climate, we should be prepared for more extreme weather events - in this context, we need to be ready for more severe frosts later in the season. Seeing as how some grape growing regions in New Zealand can have a potentially damaging frost in almost every month of the year (historically, anyway), this isn't good news!!!
Hands up those who thought being a viticulturist was a cushy job!!
Wednesday, April 27, 2011
Thoughts on vine density
A student asked this question today, and I spent some time on a reply. A good topic for discussion (and final exam questions??? :-)
"Can you explain why low potential soils need closer vine spacing to optimize the yield and quality and soils with higher potential need wider vine spacing?"
"My understanding is that higher soil potential leads to high vigour of the vine and should increase the density of the vine to manage that right? So therefore high potential soil should have closer spacing than the low potential soil."
My answer:
Vine spacing is one of those things that you should really try to get right when you're planning the vineyard. It's one of the reasons why detailed soil surveys are done before vineyards (incorporating variety, trellis, rootstock etc.) are designed. Get the spacing too tight, and the vines will outgrow the volume of space available to them. Get it too sparse, and the vines may not be able to take advantage of the volume allocated to them, leading to unused cropping potential.
To begin this discussion, we should first define what we are talking about. There are two types of spacing: within row (between vine) and between row.
Generally speaking, as you decrease the between row spacing, you also decrease the between vine spacing. However, there is room to move, so to speak, when practicing this.
Firstly, let me tackle the question of soil qualities and appropriate vine density (which, through altering between row and within row spacing, is what we are mostly talking about here).
If a soil is fertile, then there are two trains of thought. One is to give the vine a lot of space to express its high capacity for growth - therefore, low vine density or wide spacings.
The other is to plant with high density to get the vines competing with each other for nutrients and water.
If the soil is not very vigorous, then there are the same trains of thought. Have wide spacings and low vine densities because the vines will then have little competition (assuming weeds are kept under control) and therefore access to the most water and nutrients that they can.
This sort of spacing is used in dryland farmed areas, where irrigation not feasible. The vines are trained as bushes, with perhaps only a stake for support. Because of this, yields per hectare are low, but then at least you can get something off the land - it's just not an intensive producing area (the most planted vine data I showed in my cultivars lecture demonstrated this - Arién has the most area planted to it, but the vine density, and therefore yields, would be very low compared to some other varieties).
Or, if you can add water to the equation, you can plant them closer together so that you can get a continuous canopy and therefore more productivity per unit area of land.
So determining the appropriate vine density depends not just on the soil, but also how it's going to be managed. The question referred to this as optimising the yield, which is the key.
So, with that out of the way, let's talk about vine spacing in terms of what is practiced in the Old World versus the New World (using gross generalisations here, so please bear with me...)
In the Old World, some of the best wines come out of vineyards that are planted at around 1mx1m, or 10,000 vines per hectare. This compares to the usual 3mx2m spacings (1667 vines per hectare) in most of the early New World plantings, including a lot of Marlborough Sauvignon blanc (I assume everyone is familiar with how those spacings came about??).
The reasoning used by some is that because great wines come off of vineyards with close spacing that it must be the close spacing that contributes to that wine quality. Therefore, if we replicate that spacing in another place, we will get better wines.
However, as reasoned above, it's actually a balance of the soil and overall management that really results in achieving vine balance (open canopies and an appropriate ratio between fruiting and vegetative growth), where it's easiest to get the most quality out of your fruit. What often happens when close spacings are transplanted to another area is that the vines end up being vigorous and turn into a mess of shoots and canes that would send Richard Smart into conniptions!
Why does this happen? Well, in many New World areas, the soils are a lot more fertile and deeper than soils in the Old World, where they have been farmed for centuries (and are often on hillsides). It's true that close vine planting will result in root competition to the sides, but what if the soil is deep? The roots can grow down and away from competing roots and fine plentiful nutrients and water. Therefore, they grow like triffids, and viticulturists may resort to pulling out rows and vines to get it into balance. We just can't control growth of roots down into the soil - unless rainfall is low, and irrigation is used...
And that last point is really the crux to the discussion: viticultural management can alter what might not be the best vine spacing into a system that still produces optimum fruit. If the spacing is too tight and vines are growing out of the volume allocated to them, we can reduce irrigation, or plant a more competitive cover crop, make the weed-free strip under the vines narrower, change the training system, or, if it's dire, rip out some of the vines...
In practice, this happens all the time - though we try to get as much information as possible pre-planting, we are still just making a best-guess as to the vineyard setup - the best way to know how vines will perform in an area is to plant some and see how they go over a 10-15 year period. This is why vineyard redevelopment, as we have see in many areas due to phylloxera, for example, is really an opportunity.
"Can you explain why low potential soils need closer vine spacing to optimize the yield and quality and soils with higher potential need wider vine spacing?"
"My understanding is that higher soil potential leads to high vigour of the vine and should increase the density of the vine to manage that right? So therefore high potential soil should have closer spacing than the low potential soil."
My answer:
Vine spacing is one of those things that you should really try to get right when you're planning the vineyard. It's one of the reasons why detailed soil surveys are done before vineyards (incorporating variety, trellis, rootstock etc.) are designed. Get the spacing too tight, and the vines will outgrow the volume of space available to them. Get it too sparse, and the vines may not be able to take advantage of the volume allocated to them, leading to unused cropping potential.
To begin this discussion, we should first define what we are talking about. There are two types of spacing: within row (between vine) and between row.
Generally speaking, as you decrease the between row spacing, you also decrease the between vine spacing. However, there is room to move, so to speak, when practicing this.
Firstly, let me tackle the question of soil qualities and appropriate vine density (which, through altering between row and within row spacing, is what we are mostly talking about here).
If a soil is fertile, then there are two trains of thought. One is to give the vine a lot of space to express its high capacity for growth - therefore, low vine density or wide spacings.
The other is to plant with high density to get the vines competing with each other for nutrients and water.
If the soil is not very vigorous, then there are the same trains of thought. Have wide spacings and low vine densities because the vines will then have little competition (assuming weeds are kept under control) and therefore access to the most water and nutrients that they can.
This sort of spacing is used in dryland farmed areas, where irrigation not feasible. The vines are trained as bushes, with perhaps only a stake for support. Because of this, yields per hectare are low, but then at least you can get something off the land - it's just not an intensive producing area (the most planted vine data I showed in my cultivars lecture demonstrated this - Arién has the most area planted to it, but the vine density, and therefore yields, would be very low compared to some other varieties).
Or, if you can add water to the equation, you can plant them closer together so that you can get a continuous canopy and therefore more productivity per unit area of land.
So determining the appropriate vine density depends not just on the soil, but also how it's going to be managed. The question referred to this as optimising the yield, which is the key.
So, with that out of the way, let's talk about vine spacing in terms of what is practiced in the Old World versus the New World (using gross generalisations here, so please bear with me...)
In the Old World, some of the best wines come out of vineyards that are planted at around 1mx1m, or 10,000 vines per hectare. This compares to the usual 3mx2m spacings (1667 vines per hectare) in most of the early New World plantings, including a lot of Marlborough Sauvignon blanc (I assume everyone is familiar with how those spacings came about??).
The reasoning used by some is that because great wines come off of vineyards with close spacing that it must be the close spacing that contributes to that wine quality. Therefore, if we replicate that spacing in another place, we will get better wines.
However, as reasoned above, it's actually a balance of the soil and overall management that really results in achieving vine balance (open canopies and an appropriate ratio between fruiting and vegetative growth), where it's easiest to get the most quality out of your fruit. What often happens when close spacings are transplanted to another area is that the vines end up being vigorous and turn into a mess of shoots and canes that would send Richard Smart into conniptions!
Why does this happen? Well, in many New World areas, the soils are a lot more fertile and deeper than soils in the Old World, where they have been farmed for centuries (and are often on hillsides). It's true that close vine planting will result in root competition to the sides, but what if the soil is deep? The roots can grow down and away from competing roots and fine plentiful nutrients and water. Therefore, they grow like triffids, and viticulturists may resort to pulling out rows and vines to get it into balance. We just can't control growth of roots down into the soil - unless rainfall is low, and irrigation is used...
And that last point is really the crux to the discussion: viticultural management can alter what might not be the best vine spacing into a system that still produces optimum fruit. If the spacing is too tight and vines are growing out of the volume allocated to them, we can reduce irrigation, or plant a more competitive cover crop, make the weed-free strip under the vines narrower, change the training system, or, if it's dire, rip out some of the vines...
In practice, this happens all the time - though we try to get as much information as possible pre-planting, we are still just making a best-guess as to the vineyard setup - the best way to know how vines will perform in an area is to plant some and see how they go over a 10-15 year period. This is why vineyard redevelopment, as we have see in many areas due to phylloxera, for example, is really an opportunity.
Thursday, April 21, 2011
Significant advances in grape processing
I recently came back from helping take Lincoln University's HORT212 (Viticulture I) class around Marlborough for two and a half days, looking mostly at vineyards, but also including a very good tour through the Brancott Winery.
I think this was my 10th time on the tour, but in any case, it's always interesting to go, as you learn new things every time, and it's also fascinating to see how the wine business changes from year to year to year.
We were given a very good talk about the future by Dr Michael Trought of the Marlborough Wine Research Centre, who mentioned new harvesting technology that is being developed as I type.
This was in the news a little while ago and has created a bit of a stir. It isn't actually all that new an idea, as this article from 2008 can confirm, but it is, as far as I'm aware, the first time the technology has actually been seen working in New Zealand.
On what is a fairly ordinary machine harvester, built by ERO, is added the innovation of on-board grape processing.
Not only does the machine harvest the grapes, but it also crushes and extracts the juice out of them them (using a centrifuge), so that instead of a mix of grape skins, seeds, pulp and material other than grape (e.g. leaves, petioles and other things that get collected by the harvester) being discharged into a bin being towed in an adjacent row, clear grape juice comes out. The grape skins and seeds are discharged to the ground in the vineyard.
As Dr Trought demonstrated to us, the juice coming out of this machine was very clear, having only a small amount of solids suspended in it (after juice is pressed from the grapes, it is normally put into a tank and allowed time for the bits of grape that came out with it to settle to the bottom of the tank - the clear juice off the top is then the premium stuff). This is desirable because there is less loss of good juice during the settling process, which probably makes up for the slightly lower litres of juice recovered per tonne of grapes that the machine juicer gets compared to the conventional press.
So what this technology can deliver is pretty clear juice straight from the vineyard.
What does this mean? Well, it means that about 20% of the weight of the fruit (skins and seeds) doesn't have to be carted to the winery, only to have to be carted back out again. There's a savings here in the number of trucks/drivers/amount of fuel needed to move the grapes to the winery and then the grape solids back to a composting facility.
It means that for those varieties that can be harvested in this way, a press is not needed back at the winery. This leads to lower capital expenditure to establish a winery.
It means that fewer people will be needed to process the grapes. A plus for the winery, but not so good for those wanting to work in wineries!
Potentially it could mean that lesser amounts of processing aids are needed to recover top-quality clear juice, leading to cost savings and more efficient use of tank space.
There are disadvantages, though. Grape waste, which is normally collected from the winery and distributed back into the vineyards, cattle yards or the composting facility, are now returned in raw form to the vineyard floor. Grape skins and seed waste has a high carbon to nitrogen ratio (C:N) of about 27:1 (Ferrer et al.2001), so leaving it out in the vineyard as it is can result in a loss of root-available nitrogen to the vines. That's not to mention that it's a bit of a slippery mess!
As well, it's pretty much useless for red wine, as the colour and mouth feel properties of the wine are tied up in the seeds and skins. If you juice the grapes in the vineyard, there is no chance for these things to be extracted into the wine.
And, as well, many white wines are made using a bit of skin contact time. That is, after the grapes are crushed, the skins are left to stew in the juice for a while. This allows flavour and aroma compounds to be extracted, as well as tannins and other compounds from the skin that can have an effect on the way the wine smells and tastes. This isn't feasible with the current machine.
A significant point for New Zealand when considering this technology is that the country's most famous wine, the Marlborough-style Sauvignon blanc, actually relies on some post-crushing skin contact time to lend it some of the aroma characteristics that it's so well known for.
It's highly likely that this time and effort-saving machine may not be able to be used with the grape that makes up almost 50% of the grape area planted.
Bummer!
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