IRRIGATION: A QUESTION OF TASTE, AND WASTE

This is a huge topic. Ultimately, all practices in the vineyard will eventually play a part in the taste of the final wine, but none so much as the practice of irrigation. There is a huge debate about this between the Old and New Worlds, naturally. The Old World camp has always said that irrigation dilutes the wine and that better fruit relies upon rainfall – but they had the climate that allowed them to say that. The New World producers have always said “if a tomato needs water, you water it. Grapes are the same” – but then, they have the climate that forces them say that. The crux of the argument is that once we grow a fruit in its non-indigenous environment, and have to radically manipulate its new home in order to accommodate it, then we have irreparably altered the fruit’s taste and composition. Stuff starts growing where it does, unaided by man, for a reason.

Irrigation is a wide term, encompassing a variety of practices according to the amount of water used and the frequency with which the water is applied: from flood, or furrow irrigation, to spray irrigation, and to drip, or trickle irrigation…and them from first day of the growing season and throughout to harvest, or once a week, or once a day, or continuously … Unirrigated vines are forced to dig down deep to find moisture and they pick up nutrients through the soil formations as they do this. Irrigated vines often miss out on vital nutrients because their root systems remain on the surface, where the moisture is. So, the produces make it even easier for them – they add fertilizers to the water in the drip irrigation system (called “fertigation”!). So the vines are fed and watered without even having to get out of bed – literally. All that they need is home-delivered directly to them. They are lazy. And like lazy, spoiled children, they will not grow up into very interesting adults, will they?

 

With heat erasing varietal character and soil influences, and irrigation diluting it, good wine, forget fine wine, doesn’t stand a chance. Irrigation also is the most damaging and wasteful viticultural practice. Although Carmel Kileline MW points out in her dissertation that “while 99% of the water used in wine-making is used for irrigation rather than in the winery, grapes are still a relatively modest user of water. In Riverland (Australia), 290 litres of water are used per 750ml bottle fo wine. Rice, by contrast, requires 2,380 litres per kg, and cotton, 5,020 per lg pf cloth”. But this is a faulty argument: being the best of the worst is nothing to be proud of  - and wine is not a necessity food crop. So, perhaps some wine producers don’t feel enormously guilty. But, irrigation remains our biggest dilemma, both in terms of effecting wine’s quality and taste, and in terms of conservations practices. Does a dry region keep increasing its irrigation until they run out of water? At what point should a region change crops or consider other agricultural uses? More frighteningly, over irrigation depletes a soil and renders it unable to grow anything …. This is what we are experiencing in Australia to a devastating degree.

Growing grapes is growing fruit. The basic gardening principles and fruit-farming provide the needed guidance. Any good gardener will tell you that over-watering, either through rain or irrigation, dilutes fruit flavour and increases yield. This is the first thing one is taught in “wine school”. It is part of the Wine 101 curriculum, and it is embedded in the European psyche. It is illegal to irrigate in Europe, and for good reason: you can taste the difference.  They didn’t just make up the rule because they felt like it. If they thought irrigation was best for the vines, or that there was an easier, less expensive way to water their vines, they would have done it. What’s interesting is now that they are experiencing heat and drought in New World proportions, they suddenly are saying, “well, a bit of drip-irrigation here and there won’t hurt”.

But it can. Remember, irrigation allows the vine to be lazy; the roots stay in the top 40 centimetres of soil and don't seek out the water or nutrients in the sub-soils and sub-solum. As Dr. Emmanuel Bourguignon states: “Permanent irrigation leads to a shallow root system. You get a really big mat of fine roots in the first 40 to 50 centimetres of soil. The most fertile horizon in the soil is in that first 40 centimetres because that is where you have the organic matter. If your roots stay in that horizon you will end up with some slight vigour problems.”

This increased vigour, or vegetative growth, creates a large canopy, which is particularly problematic in sunny climates because “you end up getting massive photosynthesis – you just end up with a high level of sugar and your alcohol potential is high," says Bourguignon. "So you dilute the terroir, but you tend to increase the varietal character. You can have a good canopy and make a good varietal wine.” Think of a New Zealand Sauvignon blanc and its loud, cartoon-like varietal profile: it screams “I am Sauvignon blanc”. This is exactly the result to which Dr. Bourguigon is referring. There is nothing wrong with that if that is the result you want - if you are “making an entry-level fruity wine, but you can forget about minerality and sense of place.” But if you want to be unique, irrigation will make that very difficult.
(Source: Rebecca Gibb, One of the world's leading soil experts tells wine producers to turn off their irrigation, February 5, 2013. Note: Dr. Bourguignon and his family have worked with clients all over the world,  including Domaine de la Romanée-Conti and Domaine Dujac in Burgundy, Domaine Huet in the Loire, Vega Sicilia in Spain and Harlan Estate in the United States)

Another huge problem presented by irrigation is the increase of the soil’s salinity, which harms the grapes. In Europe, where the soils’ (terroir) are King, and the so much a part of the wine’s composition, changing its very composition will change the taste of its fruit. Salt build-up is such a problem in some southern Australian vineyards, vineyards that have had to rely upon heavy irrigation since their inception, that the winemakers have had to abandon them. Another example of how manipulating the environment eventually catches up with you. Ideally, irrigation would perfectly mimic the effect of rainfall, with a heavy “deluge” in winter or early spring, as long as the soil is not so parched and compact that it cannot store or hold the water adequately. This is often the case when the rest of the season is not humid enough and any moisture in the soil is evaporated. So, such “copy cat” actions would simply mean that the water sits on the top of the soil and causes problems.

In his article, The Dangers of Soil Salinity, Tim Teichgraeber examines the problem of salinity in the US. He quotes biochemistry professor Grant Cramer, of the University of Nevada, Reno: "Anywhere you have arid climates, you're going to accumulate salt in the soil. Australia has significant salinity problems, and I would imagine some of the North African grape growing areas have significant salinity issues too. It's a worldwide problem. Certainly the San Joaquin Valley would also have problems." Teichgraeber explains that when salt levels get high enough in the vine, the leaves start to display "leaf burn" or browning, as they do with some other vine afflictions like Pierce's disease. Another salt accumulation problem is caused by the way salts change the structure of the soil itself, and the effect that has on plants. Salt also changes the way the roots grow. “Salts are more than just the sodium chloride you might use to garnish your margarita or make your strip steak really pop. They're a whole class of ionic compounds made up of positively charged cations and negatively charged anions that are neutral when combined. Among the potentially phytotoxic salt components are sodium, chloride and boron, all of which can cause crippling decreases in vine vigor or even vine death at elevated levels.”

So perversely, the best way to cope with soils with high salinity is to flush them out with huge doses of fresh rainwater. But if these places had enough fresh rainwater with which to flush out and drench their soils, they wouldn’t need to be irrigating in the first place. I know that I am over-generalising a bit here, but when you look at this with some perspective …

LJ Johnson-Bell