Wine and drought

Few images strike home harder in times of drought than the frequently seen photographs and film footage of sheep and cattle carcasses being tipped into a pit, or the staggering movements of drought-ravaged stock as they desperately seek to extract moisture and sustenance from a landscape as dry and dusty as the moon itself.

While anyone who derives an income from farming would extend their sympathy to those adversely affected by this drought, the fortunate reality for wine is that things would have to be many times worse before we saw similar images of vines being uprooted and burned in flames.

While the impact of the drought is only now becoming apparent to many city-dwelling Australians, the truth is that many of our vineyards have spent much of the last decade operating under drought or drought-like conditions. Large areas of the country’s south-east that are habitually accustomed to having plentiful access to water have only received top-freshening rainfall in recent years that has actually done very little to replenish moisture reserves in soils, or else fill dams that would normally be full to overflowing.

It is early days in this chapter, but a number of truths are already clear. There is no doubt that the 2003 vintage will be smaller than expectations. How much smaller remains to be seen. With wine, small can mean good, but not necessarily so. I’ll look at some of the variables shortly.

Some growers of irrigated vineyards in river areas will not receive their usual non-drought allocations of water. Whether they do or not depends on factors such as where they are different states impose different controls and the security level of their water contracts. Those with high security might well receive their entire allocation, while those with only ‘general’ security might have to manage with as little as 10 of normal. Naturally, life will be tough for those having to manage on a greatly reduced water budget.

It will be a season for the viticulturists. There’s no doubt that the best-managed vineyards will fare better than those whose operators bury their heads in the sand. Unless the weather pattern changes very soon, mature vineyards set up to face the drought with lower crop expectations and deeper root systems will unquestionably perform better than those managed to maximise yield potential irregardless of the seasonal circumstances.

The weather forecasts are not good. Most reliable long-term weather forecasts suggest that the next substantial rains won’t occur until autumn at the earliest. That means it’s unlikely that those who gamble on a weather change will get out of jail.

It is already dire in many of the drier regions. Some growers in the drier areas of western Victoria are already having to truck in just a few thousand litres of water so they can spray their vineyards with essential traditional treatments like sulphur.

Viticulture and water



At its best, irrigation for viticulture is one of the most efficient economic uses for water that there is, especially when you consider the wine industry’s unsurpassed ability to add value to an agricultural product: grapes. Grapevines are amongst the lowest water usage plants in agriculture, and the efficiencies in the winegrape industry are amongst the best in the country.

There are however still two major weaknesses in the wine industry’s approach to water usage. Too much water is still applied to grapevines through archaic and inefficient mechanisms, leading to over-application, massive wastage and subsequent raising of water profiles in soils causing increased salinity issues. Secondly, right across the entire wine industry, too many vineyards have their yields pumped up through excessive watering, leading to thin, simple and inadequate wines often seriously deficient in quality and character. From the Mornington Peninsula to the Murray Valley there are countless examples of the direct consequences of growers aiming to crop too high and bumping up their yields with excessive watering.

To counter this trend, recent years have witnessed a move by some larger purchasers and growers in the irrigated inland river areas to pay a premium for quality over quantity, which brings an inevitable reduction in water usage. Furthermore, there has been an increased awareness at the premium end of the market that the better wines do in fact come from smaller, better-managed yields from balanced vineyards.

Much of the water applied to Australian vineyards today is accurately metered out according to how much moisture the soil actually loses. There’s a range of monitoring equipment available to achieve this with accuracy. The vineyard established by Pepper Tree in Coonawarra is automatically irrigated by a computer based in the Hunter Valley, which is able to take readings from small individual parcels of the vineyard and irrigate them in isolation from the rest.

What happens to a vine in drought?



Drought is most damaging to vines in the early stages of the growing season, for shoot growth and early berry growth are very sensitive to water stress. Such drought-affected vineyards are likely to have significantly lower yields than normal. Throughout this summer grape growers will tell you that because yields are down, quality will necessarily be up. Just ignore them.

As the season progresses and the vine focuses on ripening its fruit, its ability to photosynthesize – the process that produces carbohydrate in the leaves – is directly linked to the soil’s ability to hold water and the roots’ ability to find it. If photosynthesis is reduced, the actual process of sugar and flavour accumulation are retarded, leading to thin, greenish and soupy wines lacking structure and intensity. If this occurs in the presence of extreme heat, as appears likely this coming summer, sugar levels in grapes are likely to rise largely through evaporation, creating grapes that might be sugar-ripe, but lacking in genuinely ripe flavours.

Right now, Australia is in a one-off situation when around half its entire crop is coming from exceptionally young vineyards. Young vines, especially if they have been irrigated since planting, tend to have shallow and under-developed root systems. They are exceptionally vulnerable in times of drought. While their survival is not yet in question, they are unlikely to perform well if their water supply is significantly limited.

Old dryland vineyards lie at the opposite extreme. They have extensive root systems of substantial depth and can find water where few other plant species would survive. Our oldest vineyards have seen drought before and survived, even making the occasional great wine in the process. 1983 Grange is an example that readily comes to mind; a classic wine from a season of painfully few highlights.

A combination of vine age, vineyard management and luck will determine whether or not most of the country’s premium wine vineyards will harvest good grapes in 2003. If the vineyards are set up for drought, and if the anticipated heat doesn’t eventuate, they should make good wine. They need to be pruned and then shoot thinned for smaller crops than usual. They should be mulched to conserve water, and any inter-row crop that might compete for moisture should be removed. Every effort should be made to protect the developing fruit from excessive direct sunlight, which can cause sunburn and evaporation, not to mention the ‘cooking’ of flavours in extreme heat. Too much canopy, however, and the vine uses too much water.

Most of the flavours accumulate in grapes during the final stages of ripening. While vines are more resilient to water stress at this time, stressed vines tend not to produce the bright, vibrant fruit flavours expected from Australian vineyards. The flavours produced are more dehydrated and desiccated; the wines dull, tired and cooked. They have less complexity and are relatively short-living.

If the summer is as hot as it is likely to be dry, vineyards will be hit with the double whammy that their already low crops will be unevenly and imperfectly ripened. Their fruit is likely to reveal the under-ripe/over-ripe flavours seen in years like 1997 and 2000 for South Australia, but in these circumstances they would be doing well to make wine even of the quality of these two difficult vintages. The wines would likely reveal stewed, pruney over-ripe characters as well as herbaceous, greenish under-ripe flavours. Hardly a happy prospect, or a long-term one!

For many of Australian vineyards that have already been experiencing water stress for the better part of the last decade; it should be business as usual. The tried and true adage will be demonstrated yet again; the best vineyard managers will produce the best wine. Please login to post comment