In episode 48 of the Vineyard Underground podcast, we have a conversation with Dr. Markus Keller of Washington State University about the advances in vineyard nutrition monitoring. Dr. Keller shared his extensive knowledge of the importance of nutrient management in viticulture, drawing from his rich background and current research. Below are a few of the things we learned.
The Vineyard Nutrient Cycle
Nutrients enter through natural sources such as soil organic matter, nitrogen-fixing legumes in cover crops, or from fertilizer applications. Losses of nutrients occur when nutrients leave the vineyard setting through grape harvest, pruning, and degradation of soil organic matter. Nutrients are then recycled back to the vines from leaves as they are senescing, supporting future growth. However, early frosts can disrupt this recycling by removing leaves before they send valuable nutrients and carbohydrates back into the vine structures, posing a challenge in northern climates. Effective vineyard nutrient management is important, requiring a balance between inputs such as fertilizers and outputs such as harvest and pruning materials to maintain soil fertility, support healthy vine growth, and ensure sustained productivity and grape quality.
Assessing Nutrient Loss & Management in Vineyards
To assess whether a vineyard has experienced excessive nutrient loss, particularly nitrogen, you must monitor the vine response. Slight nitrogen stress can enhance phenolic compounds — tannins and anthocyanins — which improve wine texture and color. However, excessive stress can be detrimental. A controlled deficit is the goal to optimize phenolic accumulation without harming the vine. Similarly, with potassium, the aim is to avoid high concentrations that raise fruit pH. Using cover crops to compete for potassium uptake can help manage levels in regions with naturally high potassium soil.
Innovative Nitrogen Management in Vineyards
Dr. Keller’s research shows that applying nitrogen directly to vine leaves is as effective as traditional soil application in achieving optimal YAN levels (150-200 mg/L). This method significantly reduces costs and integrates easily with other treatments. It not only ensures efficient YAN optimization but also suggests potential impacts on wine’s phenolic content, offering a promising area for further research.
If you want to learn more about advancements in vineyard nutrition monitoring, check out https://www.vineyardundergroundpodcast.com/vu048.
