A comprehensive study has been conducted over three years in a Marlborough Sauvignon Blanc vineyard by grape grower Kristy Harkness and viticulture researcher Dr. Mark Krasnow. The study has demonstrated that hemp is a viable cover crop, particularly within New Zealand’s Sauvignon Blanc vineyards.
According to the findings reported by New Zealand Wine Grower, hemp did not pose competition to the grapevines and had a positive impact on both the soil and the quality of the wines produced. Remarkably, during New Zealand’s dry season, the hemp established itself without additional irrigation, even when other crops struggled to survive.
This unique ability allowed the hemp plants to continue sequestering carbon for an extended period into the season. These discoveries hold significant promise, especially for regions in the United States like California, where the wine and hemp industries are thriving. The application of these findings could benefit the future of both sectors.
To gauge the impact of using hemp as a cover crop and intercrop in vineyards, researchers planted industrial hemp seeds within the middle rows of the vineyard. The hemp plants exhibited exceptional adaptability, thriving without extra irrigation. Surprisingly, instead of negatively affecting wine production, their presence improved quality compared to grapes grown without hemp intercropping.
The researchers noted that hemp plants developed robust root systems extending at least 30 cm deep and displayed the ability to thrive within compacted tractor wheel tracks in the rows. This root system effectively mitigated the compaction resulting from vineyard operations.
Additionally, during the 2019 harvest, juice and must samples from the hemp-infused area demonstrated a greater yeast species diversity than the control group, resulting in superior wine production.
The study also underscored the significance of high-quality hemp seeds, emphasizing their importance for ensuring successful growth. The study noted that quality seeds are essential for all crops, with hemp being no exception, as evidenced by the stark contrast in hemp growth between the 2020-21 season and the other two seasons.
Harkness highlighted hemp’s potential to provide additional advantages to the soil and wine, describing this discovery as “truly exhilarating.” She further explained that the variations in native yeast populations introduced by the presence of a hemp cover crop have piqued considerable interest.
While hemp enhances wine quality, it is an intriguing avenue for further research, but it’s not a direction she is presently pursuing. As a grape grower, I primarily emphasize cultivating the finest quality grapes and enhancing soil health in our vineyards.
Despite the substantial size of some hemp plants, Krasnow expressed his surprise at the absence of competition between hemp and grapevines. Although the study did not specifically investigate this aspect, Krasnow pointed out the potential benefits of integrating hemp with other cover crops, such as clover for nitrogen and buckwheat for promoting beneficial insects in vineyards.
This approach can yield superior grapes with reduced resource inputs, carbon sequestration benefits, and the added advantage of alleviating soil compaction in tractor wheel tracks—an issue of great concern in vineyard soils.
These discoveries may usher in the creation of vineyards without the need for traditional grass planting and subsequent mowing. Instead, a diverse cover crop blend featuring hemp could be sown and easily managed with minimal rolling as vineyard workers traverse the rows.
According to Krasnow, this innovative approach promises to enhance grape quality, save water, promote bee-friendly ecosystems, reduce diesel consumption, and prove more cost-effective. He emphasized that mowing doesn’t contribute to the quality of the wine. While it might offer an aesthetically pleasing appearance as people drive by, it isn’t particularly beneficial for the soil.
The study’s discussion suggests that due to the promising potential of hemp as a cover crop, particularly in terms of soil improvement, potential wine quality enhancement, and the prospect of generating additional income from the property, it is anticipated that an increasing number of grape growers will explore the integration of hemp, either as an intercrop or as part of a more diversified cover crop mixture.
The researchers also emphasize the need for further research to assess the impact on wines, including their quality, as well as the potential for the pickup of cannabinoids and/or off-flavors in red wines cultivated in proximity to hemp plants.
The three-year study indicates that hemp emerges as a viable vineyard cover crop option. The hemp plants that successfully established themselves flourished even during an exceptionally arid season, requiring no additional irrigation—unlike cover crops with shallower roots. This unique attribute enables hemp to persist and sequester carbon when other cover crops typically wane.
Furthermore, the presence of hemp had no discernible adverse effects on vine growth, nutrient levels, water relations, fruit development, quality, or vine productivity. This suggests that integrating hemp as a cover crop or intercrop is unlikely to result in any income loss for vineyard operations. Notably, the 2020-21 season demonstrated the importance of sourcing high-quality seeds from reputable vendors for successful hemp growth.
The soils within the hemp-covered area exhibited higher organic matter and total carbon levels, which bode well for the long-term health and fertility of the soil. Notably, these differences were most pronounced at depths of 40-80 cm, indicating that hemp facilitates deeper carbon sequestration within the soil profile compared to other cover crops or vegetation.
Additionally, findings from the 2019 season revealed that the presence of hemp in the vineyard led to a greater population of native yeast on the grapes, facilitating a healthy, uninoculated fermentation process. The wine quality from grapes grown alongside hemp surpassed that of the control group.
The conclusion that hemp’s presence in the vineyard fails to impact the vines negatively and offers beneficial effects on soil and wine quality is truly exciting and warrants further exploration and study.
In summary, the three-year study underscores hemp’s potential as a valuable vineyard cover crop. Hemp’s ability to thrive in arid conditions without supplemental irrigation, its minimal impact on vine growth and productivity, and its positive influence on soil quality and wine production make it a promising addition to vineyard practices.
However, it is crucial to source high-quality seeds for successful hemp cultivation. These findings open the door to further research and experimentation, offering exciting prospects for the future of vineyard management and wine quality improvement. (Full Story)