Seresin Vineyard: Stem Water Potential, Irrigation and Grape Quality
Seresin is the largest Demeter Certified Biodynamic vineyard in New Zealand. Based in Marlborough, the vineyard spans 50 planted hectares. The vineyard is managed holistically, with a diversity of animals and plants which formulate an ecosystem, including: olive trees, pine nut trees, sheep, chickens, cows, goats, ducks and bees.
Seresin have been using Sectormentor to monitor their vineyard activities, including creating yield predictions from their bunch weights, tracking their yield, and visualising their phenology activity. This week, we chatted to Seresin’s vineyard manager, Cameron Vawter, who shared with us how the vineyard team are now tailoring their Sectormentor app to specifically monitor Stem Water Potential (SWP) in order to determine irrigation habits that maximise grape quality.
SWP is a way of monitoring water stress in a vine. The process involves taking a vine leaf and placing it inside a chamber in which pressure is applied to the leaf to push the water out. The chamber measures how ‘tightly’ the leaf holds onto water, reflecting its vine water status or water stress level. The readings from these tests are negative, but the team input them as positive and read the graphs inversely to simplify the data visualisation.
Above we can see a graph of the Stem Water Potential of two of Seresin's blocks, tracked from late January to early March; the grape harvesting season in New Zealand.
‘When I begin the irrigation season, I might be at a 5 bar. Dependent on soils and weather I might go up to a 12 bar, at which I’ll irrigate and see the graph go back down to an 8 bar. We have different thresholds for different varieties and different desired quality outcomes. When I see my SWP go down, I won’t irrigate again until I start to see my SWP increase again. Now I want to assess which irrigations work best for the vines; I’ve found so far that longer, deeper and infrequent irrigations are the more effective.’
– Cameron Vawter
The main driver for SWP testing at Seresin is to reduce the amount of water used in irrigation, and therefore improve grape quality: ‘We know that decreased or better timed irrigation will improve our wine quality, as well as save water’. Reduced irrigation reduces water dilution within the grape; this results in smaller grapes with better flavour profiles. Some vineyards irrigate frequently to increase the weight and yield of their harvest, but the team at Seresin believe in ‘quality over quantity’. Cameron also describes how over-watering vines can lead to ‘over stimulated canopy growth, which can increase disease pressure, the need to spray your vines, and vine trimming. This all takes away from the ripening process of the vine’. In this sense, targeted irrigation will lead to a lot less work in other areas of vine and inter-row maintenance.
‘Lots of viticulturists will look at the vines and try and make an irrigation decision based on appearance, but vines can be deceiving. When you are working with multiple different varieties, sizes and quality parameters of the vines, they will all have different watering needs.’
– Cameron Vawter
Cameron plans to put his irrigation quantities into the Sectormentor app next, so he can see their direct relationship with his SWP readings. He has previously found that his SWP figures spike after a short irrigation, ‘by doing a small irrigation, you are actually adding more stress to the vine in a short period of time; if you are able to do it right, your SWP will be lower for a longer period of time before it starts to rise again’.
Overall Key Learnings
- Longer, deeper irrigations decrease vine stress for a longer period of time
- Vines do not need as much water as you think
- Specifically timed and data driven irrigation habits, lead to better quality grapes
A warm thank you to Cameron Vawter for speaking to us about the exciting SWP experimentation happening at Seresin Vineyard. We love hearing about new ways that Sectormentor can be adapted to support regenerative experiments on vineyards!
If you would like to get in touch with us, please contact us at info@vidacycle.com. If you are thinking of buying Sectormentor, contact us or click here.
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