PROSSER, Wash. — New research from Washington State University could help grape growers improve nutrient use efficiency and develop a more accurate fertilizer budget, helping ensure high fruit quality, vineyard productivity, and long-term economic and environmental sustainability.
The findings, published in the American Journal of Enology and Viticulture, show that leaf fall, dormant cane removal, and environmental conditions can significantly impact nutrient loss in grapevines.
“The study highlights the importance of taking a more holistic view of vineyard nutrient management,” said lead author Nataliya Shcherbatyuk, a research associate in WSU’s Department of Horticulture. “While growers routinely account for nutrients removed through harvested fruit, there are other pathways that receive much less attention despite their potential contribution to annual nutrient losses. This research is about understanding how vineyard systems function and how we can use that knowledge to make more informed management decisions.”
Part of the USDA-funded High Resolution Vineyard Nutrient Management Project, the study analyzed nutrient loss data on Syrah, Sauvignon blanc, and Chardonnay wine grape cultivars as well as Concord juice grapes. The samples came from irrigated vineyards in eastern Washington.
The scientists found that nutrient loss is heavily dependent on crop yield. Nutrients such as potassium and nitrogen are lost in the largest quantities through harvested grapes, while leaf fall accounted for significant calcium and nitrogen losses.
“In some cases, nutrient losses through leaves were much larger than many growers might expect,” Shcherbatyuk said.
The study also showed how changing weather patterns can make nutrient management difficult for growers.
Drought conditions can negatively affect a vine’s nutrient uptake, while strong winds often carry grape leaves out of the vineyard, depositing them where the nutrients are inaccessible. Increasingly warmer falls often mean the plants stay active later, only to lose their leaves to a sudden frost before the nutrient recycling process is complete.
“At the end of a growing season, the dying leaves will recycle nutrients back into the vine’s roots, where they are stored until the next season,” said Markus Keller, project director and Chateau Ste. Michelle Distinguished Professor in WSU’s Department of Viticulture and Enology. “With an early frost, that doesn’t happen. If early frosts occur on a routine basis, the plants will eventually become nutrient deficient because those nutrients aren’t available at bud break the following season. Growers must then compensate with fertilizer.”
Similarly, a warm spring encourages earlier bud burst, but freezing temperatures could mean the plants have to start over.
“Both situations are problematic, because you’re essentially running the vine out of nutrients,” Keller said.
Volatile weather can also impact crop yield, canopy growth, and vine biomass, which all influence annual nutrient removal. A better understanding of this relationship can help growers make more informed decisions.
“This research is an excellent example of our university’s land-grant mission in action,” said Raj Khosla, Cashup Davis Family Endowed Dean of WSU’s College of Agricultural, Human, and Natural Resource Sciences. “Our scientists are working on important research that directly impacts the health of vineyards, allowing grape growers to manage their vineyards as efficiently as possible.”
Many vineyards in the western U.S. are fertilized via drip irrigation systems that are impossible to customize for precision, or variable-rate, nutrient applications across heterogeneous vineyards, Keller said. WSU scientists have partnered with Oregon State University researchers to install a single vine drip irrigation prototype at the WSU Prosser research vineyard. Developed by an OSU team led by Chad Higgins, the mechanism could allow for more precise fertilizer application while accounting for the many variables that contribute to nutrient loss.
Other next steps include studying nutrient loss in different cultivars, vineyard sites, climates, and management sites, added Shcherbatyuk. The nutrient management project has already developed decision tools, such as leaf nutrient sensors, and maps that help growers improve their fertilizer timing while reducing unnecessary inputs.
“I hope this work helps stimulate additional discussion and research around vineyard nutrient cycling,” Shcherbatyuk said. “There is still much to learn about how nutrients move through vineyard ecosystems, and a better understanding of those processes can benefit growers, researchers, and the industry as a whole.”
Media Contacts:
Nataliya Shcherbatyuk; WSU Department of Horticulture; n.shcherbatyuk@wsu.edu
Markus Keller; WSU Department of Viticulture & Enology; mkeller@wsu.edu
Angela Sams; College of Agricultural, Human, and Natural Resource Sciences Communications; alsams@wsu.edu
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