The lead up to the Master of Wine Stage One Assessment was marked, for me at least, with a lot of stress. There seemed to be an endless amount of ground to cover, the questions for the theory part of the assessment being drawn from any of the last ten years’ worth of exams. What’s more, the presence of a compulsory question among the three we would be asked meant that we really felt we had to learn EVERYTHING. Of course, we (well, at least I) couldn’t do that, and was relying on a certain amount of luck.

Turning over the question paper when the time came to sit the exam, my heart sank. The compulsory question was: ‘How does soil influence wine quality’. This was not one of my strong points. I breathed deeply, and tried to get over my disappointment that I would not be able to show off my hard-earned knowledge on topics such as the role of oxygen or temperature in winemaking, or the measures viticulturalists can take to combat frost damage.

So, how does soil influence wine quality? The first thing you need to do when tackling this kind of question is to define soil. This is the sort of thing that sounds very easy until you actually try to do it. Soil is the ground in which a vine grows, composed of organic matter, clay and rock. It anchors the vine, as well as providing its principal source of water and nutrients.

A vineyard soil needs to provide the correct amount of nutrients to the grapevine. If there aren’t enough nutrients available, the vine will shrivel and grapes will not ripen, thus creating a thin, acidic, flavourless wine. But too much and the vine will concentrate on vegetative growth, rather than producing the high quality grapes required for winemaking. In order to grow high quality fruit, a vine needs to be ever so slightly stressed.

The same goes with water. Too much water and the vine enters its vegetative stage, but too little and it can shut down. Irrigation can help to mitigate this, but what about in parts of South Africa and California where drought conditions lead to widespread water shortages? Well, making sure your vines are grown on the right roots will help. Deep roots can help the vine to access water deep underground which it otherwise wouldn’t have been able to reach.

Making sure your rootstock is compatible with your soil type is a key consideration on how the soil influences the quality of the wine you end up producing.
There were many other things than these that I wrote about during the hour I spent on this exam question – some sensible, some less so. Whether the detail was sufficient, the argument clear enough and the key topics covered remains to be seen. Until then, it’s time to actually enjoy some wine, rather than analysing it! Cheers!