I have just got back from a very interesting residential school as part of my Bachelor of Wine Science degree. Our lecturer, Dr. Robyn Wood, had just joined the school after many years in industry and was determined to turn conventional wisdom on its head. One of her most intriguing arguments, and well scientifically backed, is for a permanent, uncultivated sward in the vineyard.

Recent conventional thinking is to allow weeds or preferably a cover crop to grow over the winter which is then “turned in” by ripping the soil in the spring. The idea is that the green material is then available for the vine – a “green manure” if you will – and competition for nutrients when the vine is nutrient-needy is eliminated. This practice is referred to as “cultivation” and is widely practiced as an alternative to the use of herbicides which is rarely used on a small producer scale these days.

Backed by some very solid academic research, she was able to show that while well intentioned, cultivation may actually decrease soil-available nitrogen levels (due to green material oxidising before being composted), lower soil moisture levels, and may lead to a deterioration in soil structure. A permanent sward, on the other hand, can increase soil microbial levels, lower canopy temperatures, capture dew, improve soil structure, prevent erosion, increase available nitrogen levels, provide an eco-system for predators of vine pests and evidence is pointing in the direction that it may even improve wine aroma [see Whitelaw-Weckert et al (2007), Zhu Mei-Xi et al (2011), Morlat & Jacquet (2004), Hanna et al (2003)].

The photo above are vines from one of my plots of Chardonnay in Dessus Les Vermots, a lieu-dit above the village of Savigny-lès-Beaune. My viticulteur has sown a sward mainly to prevent soil erosion since this vineyard is quite steep and a spring thunderstorm could easily strip the vineyard bare of topsoil very quickly. After the harvest hopefully we can look into planting some winter grasses on my other plots. I am especially intrigued about its use in Aux Fourneaux where my Pinot Noir vines are — Aux Fourneaux can get quite hot with the darker soil radiating heat back into the vine and a cover crop could help lower temperatures in the canopy and also improve the soil structure (since the soil clumps quite easily there making it more difficult for the vine to access water and nutrients). Definitely an interesting idea to explore some more.

 

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