Reyneke Wines and Biodynamics
I am writing this on the train home from London where I spent the last three days at trade wine tastings. There were plenty of wines to taste, many good but the absolute highlight of the trip was an hour spend listening to Johan Reyneke of Reyneke Wines. A native South African Johan describes himself as a wine farmer, but he started out as a philosophy graduate and he spoke with a conviction and eloquence that I found captivating. Johan has been making wine as Reyneke since 1998 when he took over the running of his family’s farm. The farm was originally farmed conventionally but since taking over Johan went over to biodynamics. Having seen the evolution from one system to the other he is particularly well placed to explain the changes that result. Biodynamics is an approach originally proposed by Austrian Philosopher Rudolph Steiner way back in the 1920’s. The shorthand way to think of it is like organic agriculture taken one stage further, so the vineyard is treated as an organism whose health the farmer carefully protects. This means that no agrochemicals are used and there is a big focus on biodiversity and vine health. The difference I found in Johan’s explanation of Biodynamics was that he took sometimes new age sounding principles, and tied them back to practical, rational explanations. Here are a few of them:
- Johan maintained that the humus (organic matter) content of soil has a big impact on vine health and also on soil acidity. Johan explained that scientific studies have shown that at 5% soil humus the vines are 3 to 4 times more disease resistant than at the 1% you would see in a non-organic vineyard. When Johan took over the farm the level was around 0.9%, it is now 4.9% and the vines are far less prone to disease.
- Johan felt that a side benefit of the higher level of soil humous is that the soil acidity has decreased. At the same time as this the acidity of the grapes and correspondingly the wines has increased. So much so that now no tartaric acid is added during winemaking. This is pretty rare in the wine world but the result certainly seems to be wines that are really well integrated.
- All of the wines are made with wild yeast fermentations. This is a technique that allows fermentation to start naturally from yeasts that are present in the vineyard and winery. The alternative is to add cultured yeast, something winemakers do to reduce the risk of a fermentation “sticking” which is when fermentation stops unexpectedly. Johan claims he has never had a fermentation stick and attributes this to healthy populations of yeasts that are not routinely killed off by fungicides and other agrochemicals.
- One of the principles of biodynamics is the use of cow’s horn manure and other biological preparations. For the horn manure, dung from a lactating cow is buried in a cow’s horn in the vineyard in Autumn. The following Spring the horn is dug up, the manure mixed with water and stirred with a carefully defined vortex motion and the resulting mixture spread at dusk onto the vineyard in very dilute quantities. Johan describes the reason for this, initially crazy sounding process, in terms of the microbial health of the vineyard. He claims that scientific testing has shown the dung to be incredibly rich in microbial life. The vortex stirring introduces oxygen to the mixture and spreading it around the vineyard means more microbes in the soil. The evening timing he suggests is simply to avoid heat from the sun that could kill the microbes before they can find their way into the soil.
- Another crazy sounding idea is that the wine should be racked (moved from one barrel to another) on dates dictated by the phase of the moon. Initially this sounds far fetched, but Johan’s explanation is that density of sediment within the barrels is affected by gravity and that this varies with the position of the moon. On this point though I remain a little skeptical as the daily percentage variation in the Earth’s gravity field is small (less than 0.0001%) and it seems unlikely to make a significant difference, but at least there is something here that could be a rational explanation.
- One comment I found particularly convincing was on the problem of Leaf Roll virus. This a common viral disease of vines, spread in South Africa by the saliva of mealybugs. Since moving over to biodynamics the virus has stopped spreading. Johan said he did not understand why until he pulled up one of the now plentiful dandelion’s in the vineyard and found it’s roots infested with mealybug. His suggestion is that the bugs simply prefer their natural habitat of dandelion to the vines. In the past the dandelions would have been seen as weeds and dealt with accordingly.