The NGRA-initiated HiRes Vineyard Nutrition research project launched a podcast this fall, ably hosted by Dr. Patty Skinkis, Professor and Viticulture Extension Specialist at Oregon State University, who also leads the Extension component of the project. In this second episode, Patty chats with Project Director Dr. Markus Keller, the Chateau St. Michelle. Distinguished Professor of Viticulture at Washington State University’s Irritated Agriculture Research and Extension Center. He shares how he came to lead the project, what they’ve learned so far and anticipates outcomes of the work. Read on for excerpts from the episode, or click to listen in on the complete conversation or read the full transcript. And consider subscribing for all the updates from this important project!

Patty Skinkis: Vineyard nutrition is an important part of vineyard health and most grape growers would agree it’s a foundation to maintaining a productive vineyard. However, it is challenging to know how to best monitor and manage vineyard nutrition amongst different growing regions, climates, weather conditions and crop production goals. While there has been research conducted on vineyard nutrition over the past 50 years, some basic discoveries and refinement of methodology are required. Since 2020, a team of 15 scientists and eight institutions across the US have been working together to address vineyard nutrition through better monitoring techniques and guidelines for grape production across the nation and all grape markets, including table, raisin, juice and wine grapes. This project is possible through a grant from the USDA’s National Institute of Food and Agriculture’s Specialty Crop Research Initiative (SCRI).

Markus, I have some questions that I hope will provide the audience with some background on the project and some insight into what’s going on in your research lab, and some of the bigger takeaways from the project after the next four or five years. But first, how did you decide to lead this big project?

Markus Keller: In fact, I didn’t decide on leading this group—it was decided for me. It was actually NGRA, the National Grape and Grape Research Alliance, that contacted me in 2019. They had already developed a pre-proposal, or a project, as part of their Integrated Production Systems Committee, and they approached me and asked if I would lead this project and develop it into something that maybe the SCRI would fund, and they helped assemble the team. You were part of that effort, Patty, as were a bunch of other people across the U.S. They [NGRA] also helped us put together the industry advisory panel for this project. The rest is history.

Patty: Can you tell us in a little bit about the research you’ve been doing for this project?

Markus: We are working on a mix of field and pot experiments. We have several field trials going on, all of them in commercial vineyards. Of these experiments, we’re testing nitrogen rate and timing of application in Syrah, Sauvignon Blanc and Concord, so, two wine grapes; one red, one white and one juice grape variety. And then we’re also testing potassium rates application in a Chardonnay block, as well. In all of these cases, we’re looking at the effects on growth, yield of course, yield components, fruit and wine composition. In some cases, like Syrah and Chardonnay, we’re also transporting our grapes from the field to the WSU Wine Science Center and they’re making wine from those different treatments, looking at wine composition, chemical composition, sensory and so on.

The focus with the nitrogen trials is mostly on phenolics, anthocyanins, tannins, flavanols and so on, vs. yeast-assimilable nitrogen or YAN. We’re also looking at foliar vs. soil application of nitrogen, as well as different rates of nitrogen. In the potassium experiment, we are looking mostly at the relationship between pH and acidity.

Of course, in all these trials, we’re also supporting remote sensing of grapevine nutrient status using spectral imaging, which is a big part of this project. That’s done by our colleagues from the WSU Center for Precision Agriculture and Automation Systems and other groups in the other states that are doing similar measurements in their production environments.

The final thing (we’re looking at is) the nutrient replacement budget. We’re noticing that growers typically do not consider how much nutrient they are losing when the leaves fall off, and in windy climates like Eastern WA, blow away. We want to know: how much are we losing, how much do we have to replace? It’s obvious that we should replace what we’re taking out with the fruit that we’re removing at harvest. But it’s not so obvious that we should also replace what we might be losing with the leaves.

Those are the field experiments. Then we have some pot experiments, which are really just getting started. They’re mostly designed to look at uptake and distribution, especially of nitrogen and potassium. So, when do vines take up most of those nutrients? How do they allocate them to the fruit versus the leaf versus the roots, and so on? And what is the influence of, for example, water deficit or vapor pressure deficit? (Water deficit in the soil or in the air which is linked to temperature and humidity.) Just a little finetuning of what we’re doing in the field, with more defined treatments and obviously, smaller plants.

Patty: What do you think are the biggest takeaways producers across the US might obtain from this project?

Markus: A primary objective is to revise nutrient standards for tissue sampling rather than relying on standards that were developed inthe 1960s for table grapes in California and applied for all grape types across the nation. We want to have nutrient tissue standards coupled with sampling protocols, which would tell you where to sample, when to sample and what type of tissue to sample. Should you sample petioles or leaf blades? Keep them separate or pool them? Can you sample something else?

A second very important aspect of this project is remote sensing. Whether we use a drone flying over the vineyard or a set of cameras mounted on a tractor or an ATV, we would like to use something that remotely senses, non-destructively, the nutrient status of a plant, and therefore, vineyard. The sensors would detect reflected light spectra that are correlated with nutrient standards we’re developing that can then be used to map the whole vineyard, rather than just having a single sample for an entire vineyard block. You now have a map that details the nutrient status of that vineyard and that is available, hopefully, the next day, so a grower could act upon that map, applying fertilizer specifically where it’s needed.

Finally, we want to have recommendations that will optimize nutrient supply by grape type—wine juice, table or raisin grapes—and by region—warm, dry versus cool, wet. For example, we have Chardonnay as a common variety across the different regions in the Eastern US as well as over here in the West, both in eastern Washington and the Willamette Valley of Oregon. Hopefully, by testing the same set of standard protocols on Chardonnay across the nation, we should be able to tell whether something is a soil-based influence or climate-based influence. Do we need to adapt nutrient standards for a single variety depending on the region? Or can we use just a single, one size fits all approach for a specific variety?

Those are the main takeaways: remote sensing, revised nutrient standards for tissue sampling and recommendations for optimizing nutrient supply by grape type, market or maybe even by variety, ultimately.

Patty: For more information about the project team, about Markus and what we’re doing, you can go to https://highresvineyardnutrition.com, where we have project reports and more podcasts to come.

Episode 1 of the HiRes Vineyard Nutrition podcast featured NGRA Board Chair Russ Smithyman chatting about how the project came to life. Check it out!