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THE WONDERS OF COVER CROPS

There are few things more beautiful to a viticulturist’s eye than a neatly pruned vineyard in the middle of winter, with a good stand of cover crop between each row. A good, winter cover crop programme is essential in controlling weeds, improving the soil structure and even in building up the soil nutrient levels as well as beneficial soil microbes.

Most wine farms plant just one type of cover crop to save costs and allow for easy sowing during the planting season. Here at Aaldering Vineyards & Wines, we do things a bit differently. Our mission to consistently produce the best possible wines from our vineyards requires precision viticulture – which has taken us down an alternative route.

Through careful soil analysis, vine monitoring and consultation with one of South Africa`s top cover crop experts, we follow a mixed cover crop sowing regime – tailored to target certain weeds and improve soil structure and nutrient levels on a block-by-block evaluation basis.

Implementing this system does cause a viticulturist a few headaches, as exact levels of each crop need to be mixed specifically for each block and sown equally through the vineyard. It’s easy to apply, say, 50kg of korog (a type of grain commonly used as a cover crop) per hectare, but try to apply 2kg of tiny mustard seeds to a hectare, and you are faced with all kinds of challenges.

Take a look at the following examples of our programme.

On our newly planted vineyards where the soil structure has been recently prepared and soil compaction is thus not a problem (yet weeds are), we sowed korog as well as vetch (a legume). The korog grows fast and out-competes the weeds, thus drastically cutting down the use of herbicides and environmental damage. The vetch provides nitrogen fixation in the soil and improves growth – which we want – to ensure the young vines grow up healthy and strong. Vetch also improves soil structure, which leads to better moisture retention, vine root development and soil biological activity, and healthy insect populations just below and just above the soil surface. All of these factors ensure that our young vines put down roots deeply, so that we can harvest their grapes for many years to come.

In our older vineyards (see our Cabernet Sauvignon block and its cover crop in the pictures above and below), soil compaction and nutrient levels are a concern, as well as soil structure. Weeds are less of a concern due to a continuous weed control programme over previous years. Here, we sowed korog, vetch and radishes. Radishes have a deep, thick tap root that grows and breaks up any soil compaction over the years, thus improving drainage, aeration and the microbes in the soil.

Once the cover crops die off, they create a mulch for the vines during their growing season, which also benefits the soil in many different ways – so that future generations will be able to cultivate it.

With this approach to cover crops, we at Aaldering ensure that our vines are given the best chance to produce the best wines possible, while cutting down our herbicide usage by up to 80%. So we lift a glass of Pinotage and toast science, the art of viticulture and a better future for all.

Cheers!

Reinhard Odendaal
Viticulturist / Winemaker

 

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