New research carried out over three years in Marlborough Sauvignon Blanc vineyard by grape grower Kristy Harkness and viticulture researcher Dr. Mark Krasnow has found that hemp is a viable cover crop, at least when it comes to the New Zealand Sauvignon Blanc vineyards. 

The research, as  outlined by New Zealand Wine Grower, found that the hemp did not compete with the vines and beneficially affected soils and wines. During the country’s dry season, the hemp also became established without supplemental irrigation when other crops failed to survive, allowing the plants to sequester carbon longer into the season.

For U.S. regions like California, which have both booming wine and hemp markets, these findings could potentially prove useful for the future of both industries.

Assessing Hemp’s Impact on Wine Vineyards

To assess the effects of hemp as a cover crop and intercrop on the vines and vineyard soil, searchers sowed industrial hemp seeds in the mid row of the vineyard. The hemp plants showed a superior ability to acclimate without additional irrigation, and rather than having a negative effect on the wines, it actually improved the quality compared to grapes not grown alongside hemp.

“Hemp plants grew large roots to at least 30 cm, and were able to grow in compacted tractor wheel tracks in the row, where the root system can alleviate compaction caused by vineyard operations,” researchers said. “Juice/must samples from the 2019 harvest showed a higher diversity of yeast species from the hemp area than the control, and produced perceptibly better wine.”

The “stark difference” in hemp growth between the 2020-21 season and the other two seasons also showed the importance of using quality seed, according to the study, saying it was “absolutely imperative for other crops, and hemp is no exception, as strongly evidenced in this study.”

A Potential Game-Changer for the Future of Wine

Harkness pointed to the hemp’s ability to further benefit the affected soils and wines, calling the finding “very exciting.”

“The differences in native yeast populations brought about by a hemp cover crop is an aspect sparking much interest,” Harkness said. “The suggestion that hemp could improve wine quality is an interesting further study topic, but not a path I’m currently going down. As a grape grower, my focus is on producing the highest quality fruit, and improving soil health in vineyards.”

Krasnow also called the lack of hemp’s competition with grapes a “little surprising, considering how large some of the plants grow.” While the study didn’t directly assess this element, Krasnow said that he sees hemp in the mixture with other cover crops, like clover for nitrogen and buckwheat for beneficial insects, as a huge potential benefit for vineyards. Doing so could not only produce better grapes with fewer inputs and sequester carbon but also alleviate soil compaction in the tractor wheel tracks, which can be a major issue in vineyard soils. 

These findings could pave the way for a vineyard where no grass needs to be sown, leading to no mowing. Instead, a mixed cover crop sward, including hemp, could be sown, which would be simp-rolled as much when vineyard crew walk down rows. This new option would improve grape quality, conserve water, be more friendly to bees, use less diesel and be more cost efficient, Krasnow said. 

“Mowing doesn’t add to wine quality. It may look lovely and more tidy as people drive past, but it’s not that great for the soil,” he added.

“Given the possibility hemp offers as a cover crop, in terms of improving vineyard soils, potentially enhancing wine quality and offering a second income stream from the property, it is expected more and more grape growers will experiment with hemp either as an intercrop or as part of a more diverse cover crop mix,” researchers state in the study’s discussion. “Further work needs to be done on the effects of wines, both in terms of quality, but also the potential for cannabinoid and/or off flavour pickup in red wines grown near hemp plants.”

The full study can be found here.

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