12th Februay 2019
I’m at this year’s Masters of Wine student seminar in Bordeaux, listening to Kees van Leeuwen, a lecturer in viticulture at the University of Bordeaux, talk about terroir. I’ve heard him before, and he is always excellent on the subject from a scientific perspective. He suggests that there are three major environmental factors which contribute to terroir: water status; temperature and; nitrogen status. Water deficit will produce low malic content and high anthocyanins (so deep colour). Warm soils provide early budding and thus more frost risk but earlier ripening. Nitrogen is the only element which has a direct impact on wine quality, as it helps determine vine vigour and berry composition. I say that I thought potassium also can have an impact, reducing acid activity in wine (a major problem here in Burgundy in the 1960s and ‘70s) but Kees says that only rarely has an impact, whereas nitrogen is invariably important. There are some flavour impacts as well; low nitrogen levels reduce glutathione, a precursor to some of the aromas in sauvignon blanc – so low nitrogen soils may be better for red varieties.
Professor Seguin in the 1960s first described terroir as ‘a cultivated ecosystem’. It has a historical dimension because there is an element of trial and error to terroir – but the history, Kees says, does not have to be long. That bears out a lot of what is happening in (say) Margaret River, where some grapes such as riesling and shiraz have broadly been discarded as inappropriate and others are being fitted to the most appropriate ecosystem for them. But, when it has worked, as with Leeuwin Estate’s Blocks 20 and 22 which form the backbone of their great Art Series Chardonnay, it is perfect.
Kees finishes with his summary: ‘management of the ecosystem allows the maximising of terroir expression in a given site’. Human activity is just as important as the right land.