Winegrowing regions in Washington State have many unique challenges from salty soils, to low organic matter, to nematodes. Devin Rippner, Research Viticulture Soil Scientist with USDA-ARS and his colleagues at Washington State University are developing a research vineyard to study soil health building practices.

They are testing a variety of management strategies including adjusting irrigation volume to correct for salt build-up, mowing for weed management, compost applications and synthetic fertilizers, and different cover crops. The team is tracking the cost of each practice and will ultimately evaluate wine quality in the coming years.

Taking a deeper dive into the future of soil sampling, Devin explains X-ray CT imagery. He has used this technology to evaluate the structure and organic matter from soil columns and aggregates. X-ray CT imagery has also been used to evaluate the impact grape seeds have on tannin flavor profiles.

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Transcript

[00:00:00] Beth Vukmanic: Wine growing regions in Washington State have many unique challenges from salty soils to low organic matter to nematodes.

[00:00:13] Welcome to Sustainable Wine Growing with the Vineyard Team, where we bring you the latest in science and research for the wine industry. I'm Beth Vukmanic, Executive Director.

[00:00:23] In today's podcast, Craig McMillan, Critical Resource Manager at Niner Wine Estates, with longtime SIP certified vineyard and the first ever SIP certified winery, speaks with Devin Rippner, Research Viticulture Soil Scientist with USDA ARS.

[00:00:41] Devin and his colleagues at Washington State University are developing a research vineyard to study soil health building practices.

[00:00:49] They are testing a variety of management strategies, including adjusting irrigation volume to correct for salt buildup, mowing for weed management, Compost applications and synthetic fertilizers and different cover crops. The team is tracking the cost of each practice and will ultimately evaluate wine quality in the coming years.

[00:01:08] Taking a deeper dive into the future of soil sampling. Devin explains X ray CT imagery. He has used this technology to evaluate the structure in organic matter from soil columns and soil aggregates. X ray CT imagery has also been used to evaluate the impact that grape seeds have on tannin flavor profiles.

[00:01:28] Now let's listen in.

[00:01:29] Craig Macmillan: Our guest today is Devin Rippner. He is a research soil scientist with the USDA agricultural research service. He's based out of Prosser, Washington, and he's also an adjunct in the department of crop and soil sciences with Washington state university.

[00:01:46] Devin, thanks for being here.

[00:01:48] Devin Rippner: Absolutely. Pleasure to be here, Craig.

[00:01:50] Craig Macmillan: You are on the leadership team of the Washington State Soil Health Initiative. I think it's a pretty cool little program. Tell us what it is and what it's all about.

[00:01:59] Devin Rippner: Yeah, absolutely. So the Washington State Legislature allocated funding to study soil health and soil health building practices in a variety of agricultural systems and so to access that money a number of groups put in competitive proposals at the Prosser Irrigated Agriculture Research and Extension Center, we put in a proposal to study soil health in wine grape systems.

[00:02:24] Originally, we actually had it in juice grapes as well, but we were not able to get enough funding for both. Juice grapes are actually a big product out of Washington.

[00:02:32] Craig Macmillan: I did not know that. That's interesting. What varieties?

[00:02:34] Devin Rippner: Mostly Concord?

[00:02:36] I'm less familiar with it. It's something I would, I would like to work in cause they have different constraints than wine grapes.

[00:02:41] Ours is focused on wine grapes, but there are systems looking at tree fruit, at potatoes, at small crane cropping systems. There are a variety of systems that are being evaluated.

[00:02:54] Craig Macmillan: I looked at a flyer that kind of outlined some of the ideas and issues around , the Wine Grape part. Can you tell us a little bit about that?

[00:03:01] Devin Rippner: we have fairly unique soils. We have pretty alkaline soils here in Washington. We're on the arid side of the Cascades. So think Reno rather than like Seattle. we tend to accumulate salts. We also have very coarse textured soils. So a lot of sands to sandy loams or loamy sands. Very little clay.

[00:03:23] We have typically under 10 percent clay in a lot of the grape growing regions of washington. we also have low organic matter, because it doesn't rain much here. There has never been a chance for a lot of plants to grow. And so we just have never really built up organic matter. So we typically have about, let's say, maybe 1 percent to 2 percent organic matter in our soils.

[00:03:44] That's about half a percent carbon to 1 percent carbon, which is typically it's pretty low for a lot of soils.

[00:03:50] Craig Macmillan: It is.

[00:03:51] Devin Rippner: those are some of, some of the like unique challenges around soil health. There's also problems with pests. Haven't had too much of an issue with Phylloxera. That's changing.

[00:04:01] There are a variety of nematode pests that cause problems in grapes here. When you plant a vineyard into an old vineyard, you're basically putting baby vines into a place that might have a bunch of pests that aren't a big deal for really mature vines.

[00:04:14] But as soon as you put a baby in that environment, it does not thrive.

[00:04:18] Finding ways to deal with nematode pests, things like that over time , is really important. So those are kind of the things that we are, we are looking at, at our site.

[00:04:27] Craig Macmillan: What kind of practices are you investigating to address these things? I hadn't really thought of that about it till now, but nematode is a good one. that's a tough pest.

[00:04:37] Devin Rippner: funny thing is this is a long term site, right? So, so our practices for those will really come later. I had a nematologist that worked for me. And she evaluated our soils for for the pathogenic nematodes for wine grapes, and we don't really have them but the thing is they build over time, right?

[00:04:52] Just because there might be a few in that soil But when they start colonizing the grape roots over time, they can become problematic We functionally have a rootstock trial at the end of all of our experimental rows and, and rootstocks have been found to be very effective at preventing nematode problems or decreasing the severity of nematode problems.

[00:05:13] We will be able to kind of look at that with our rootstock trial.

[00:05:17] Craig Macmillan: Do you have any of the GRN stocks in that?

[00:05:19] Devin Rippner: We don't, so we have own rooted vines and then we have Telekey 5c 1103p 110r. Let's see then I think St. George

[00:05:30] I'm trying to remember what, what the last one is. It's escaping me right now. I apologize.

[00:05:34] Craig Macmillan: Well, no, it's all right. Some of the more common root stocks, basically the ones that are very popular.

[00:05:39] Devin Rippner: Yeah. Yeah. Yeah.

[00:05:41] The reality is that a lot of the like vitis rupestris, vitis riparia, , they are less prone to nematode parasitism. Than Vinifera. , that's the reality of it.

[00:05:50] Craig Macmillan: Yeah. Less susceptible. I think it's probably the best way to put it. Nothing's bulletproof when it comes to this, this problem.

[00:05:57] Devin Rippner: And Michelle Moyer in Washington has been doing a lot of work with this, with Inga Zasada, who's a USDA scientist. And their, their results are really cool. They're finding that when you try to fumigate, it helps for a little while, but the rebound is bad, and it's just easier to just use rootstocks.

[00:06:15] Craig Macmillan: Yeah. Talk to me a little bit more about, you said salinity can be an issue

[00:06:19] Devin Rippner: Yeah,

[00:06:20] Craig Macmillan: So here's the, the back and forth on that. You would think that a, a coser, your textured soil salinity would be less of an issue, but you don't get the rain to take advantage of that. Is that , the issue here?

[00:06:30] Devin Rippner: 100%. That's exactly it. We build up layers called caliche layers, which are evidence of a lack of water moving downward.

[00:06:38] So it's, it's really evidence of water moving down and then back up due to evaporation. We get big buildups of carbonates in our soils and carbonates are a type of salt.

[00:06:48] So as you apply other chemicals, Salts, a salty irrigation water , we tend to build up salts in our soils. A lot of our irrigation water comes from the Yakima River or other rivers in the area, columbia River. But there are places where people are on deeper wells and they are seeing salt accumulation in their vineyards.

[00:07:06] And it's, it's really challenging to deal with.

[00:07:09] Craig Macmillan: Do you have any strategies that you're looking at? Anything you're trying out?

[00:07:13] Devin Rippner: at our site over time, we're going to look at higher irrigation volumes versus lower irrigation volumes and seeing if that will change the accumulation of salt at our site. , that's kind of the main experiment around that with our soil health vineyard.

[00:07:27] Craig Macmillan: Obviously you're doing this with some pretty salty irrigation water and you're comparing that to less salty water. At one site, you're only gonna have one type of water, right?

[00:07:36] Devin Rippner: Right. That's not something that we'll be able to do, but one of the interesting things is we are applying compost and. Our compost can be pretty salty.

[00:07:45] So we'll, we'll be getting compost. That'll be kind of four decisiemen per meter. I I'm sorry to use those units and so that, so that is salty.

[00:07:54] Craig Macmillan: Yeah, it's salty.

[00:07:55] Devin Rippner: Young grapevines, if they grew only in that, they would really struggle. It's over the, the two deciSiemen per meter kind of threshold for grapevines. That's something where we're, you know, we are using clean irrigation water, but some of our amendments coming in can be saltier.

[00:08:10] When we have kind of a, a low and high irrigation treatment, we can evaluate the salt accumulation in the root zone. From that particular amendment, right?

[00:08:19] Craig Macmillan: What about other types of fertilizer? Are there organic fertilizers or something like that that might be less of a salt contributor than let's say a traditional nitrate based fertilizer?

[00:08:28] Devin Rippner: As it turns out, at least for us, we don't apply. a massive amount of nitrogen to our grapevines, so we're often applying between 20 and say 60 pounds of N per year which is not a lot compared to say corn or, tree fruit or, or hops or things like that.

[00:08:45] And so we, we don't, Exactly. Expect to see a buildup of, of those salts over time. Honestly, some of the organic amendments end up being saltier than our fertilizer.

[00:08:55] That's something when we do a high and low for irrigation, we will be able to look at the accumulation of, of nitrates and things like that.

[00:09:02] Cause in our arid environment, you do get accumulations of nitrate, which is kind of funny.

[00:09:06] Craig Macmillan: Yeah, that's interesting. You also mentioned the soil pH, alkalinity. What, what's going on there? How bad is it in different spots? What can you do about it? I, I'm fascinated by this because like when you look at viticulture, you have like a lot of knobs on the mixing board, right? You got a lot of sliders and, Soil , you can't slide it very well. It's like very hard to make changes to soil over time.

[00:09:33] Devin Rippner: it is.

[00:09:33] Craig Macmillan: very slow and very difficult. So I'm very interested in , this issue here.

[00:09:39] Devin Rippner: It's funny at our site, the soil pH isn't too bad. It's about 8. Across the board, from the, from the top that so, so we've been measuring from the top of the soil down to about 90 centimeters. About three feet. We do see a pH tick up in our sub soil, but still it's, it's around the eights.

[00:09:56] We actually have a lot of carbonates in our soil. There's only more organic carbon in the top six inches of our soil. And from that point on, most of our carbon is in the form of carbonates.

[00:10:06] Which is kind of unique. And so once you get down to like 60 to 90 centimeters, so two to three feet in the soil, functionally, 90 percent of the soil carbon is carbon from carbonate.

[00:10:16] So dealing with that in the region there's wide variation, so people that are planting into old wheat ground where they've used a lot of ammonium based fertilizers or urea, the pH can be in the fives. And then I, I mean, I've measured soil pH is up to about 9. 8 around here. So, so quite high.

[00:10:35] Those soils are hard to deal with. So these are carbonate buffered systems. So to try to lower the pH, you basically have to get rid of all the carbonates. And that is not really feasible. We do see in some of the vineyards that we work in. And again, a lot of this data is preliminary.

[00:10:51] I'm trying to get stuff out right now. Getting the vineyard set up has been a massive undertaking. And I've been lucky to work with a great team to, to get it done, but it has taken a lot of my time.

[00:11:01] Um, but we, we do see seasonal fluctuations with irrigation. So soils might start off with a pH around eight drop over the course of the growing season into the sixes and then as they dry down for winter time. So we cut irrigation. The pH will start to rise back up as the carbonates move from the subsoil to the surface.

[00:11:21] Craig Macmillan: Interesting. Interesting. Let's talk about your vineyard. If I understand correctly, you have a research vineyard there in Prosser that you are building from scratch or have built from scratch. Is that true?

[00:11:30] Devin Rippner: Yes. . It is a new vineyard to study soil health building practices. We just finished our second season. And we were very lucky. Vina Matos which is a company out of Portugal. They mechanically planted it for us.

[00:11:45] Scientist, so it's, it was, yeah, it was a bit of an undertaking. Even now I've gotten a lot better on a tractor than I was. And, you know, I like to run, like, I'd like to do x ray stuff. And then I'm out there on a tractor, like, yeah, doing stuff. It's a unique challenge.

[00:11:59] So we do have a vineyard manager Dr. Liz Gillespie is the vineyard manager. , she honestly does most of the tracker work. I only sub in when she's down with an illness or something like that.

[00:12:09] It's been a team effort for the last couple of years.

[00:12:12] Craig Macmillan: What are you doing in there? You've talked about a couple of topics, but, and how big is this, this vineyard?

[00:12:17] Devin Rippner: It's not that big. It's about 4. 1 acres. ,

[00:12:20] Craig Macmillan: that's, you know, for research, that's good.

[00:12:22] Devin Rippner: yeah, yeah, it is good. We functionally have a business as usual. So we call it our Washington 2021 standard. So it's kind of what growers just do. So that's spraying undervined for weed control and then just let resident vegetation pop up where it may and mow it down.

[00:12:39] Most people don't spray or till , their tractor rows. They just. Kind of let it go. We don't get that much rain. You end up selecting for annual grasses it's actually a pretty good weed composition for a tractor row. So then we start building from there.

[00:12:52] One of our treatments is what if you just mowed everywhere, right? The goal is to select for annual grasses everywhere over time.

[00:12:59] And then we have another treatment where we're mowing everywhere. But we're applying compost for fertilization. Our other treatments get synthetic fertilizers for fertilization, and then we have our compost treatment where we're mowing.

[00:13:12] Then we have an undervined cover crop, so that's like our cover crop treatment.

[00:13:16] We're curious about undervine legume cover crops. So we have a short subterranean clover that , we've seated in to hopefully eventually start adding nitrogen to the system and, and hopefully we'll be able to back off on more of the synthetic fertilizers over time in that system, but we'll let the vines guide us, right?

[00:13:35] Craig Macmillan: What species of clover is that?

[00:13:37] Devin Rippner: I'm not sure the exact, so it would be like Dalkey.

[00:13:39] it's a clover that basically has low flowers and shoots seed downward. And so , that allows it to replant itself really effectively.

[00:13:47] The flowers tend to be below the foliage. So we won't have to worry about mowing them down too badly. , they stay low. And so that's why we selected that. just to try to keep the flowers low and keep foliage away from our vines.

[00:14:01] Craig Macmillan: Anything else?

[00:14:03] Devin Rippner: Yeah, so then we have our aspirational treatment, which is kind of a mix of the subterranean clover cover crop. And then we have compost fertilization and then kind of breaking the full factorial. We're actually changing what's in , , the tractor row. We're planting an intermediate wheatgrass.

[00:14:20] We started with crusted wheatgrass. It's so funny with these experiments. , we seeded in crusted wheatgrass a couple of times and just did not take it's not very effective for competing against other weeds, and it's not very good with traffic. And so now , we're seeding in intermediate wheatgrass.

[00:14:35] , it is more traffic tolerant and is more weed tolerant. So we're hoping that we'll be able to outcompete all the other annual grasses and just have kind of a perennial grass cover crop.

[00:14:46] Craig Macmillan: Is it on these courses? So is this camp is compaction less of a problem? I would think.

[00:14:53] Devin Rippner: We do have some compaction. That we've seen out there. Certainly mechanical planting can cause some extra compaction. It, it takes a lot of force to, you know, rip a giant hole in the ground to drop the vines into. And so we do see some compaction from that.

[00:15:06] We have taken bulk density cores from all over the vineyard. And we're hoping to see changes over time in that compaction. So we've done bulk density course from under vine and then in the tractor row. And so we're hoping that over time, these various practices will alter the bulk density, hopefully lower the bulk density in the tractor row.

[00:15:27] Craig Macmillan: And then I'm assuming that you're also keeping track of costs for these things.

[00:15:32] Devin Rippner: yes, we have been keeping track of costs. We are keeping track of the hourly labor , for mowing. Honestly, we've, we've purchased some undervine mowers and , we have really struggled to find a good solution for our young vines.

[00:15:45] We're going to, Purchase another one soon. The biggest thing is that if you have a swing arm on it, it's got to be gentle enough that it, it'll push out of the way , with a bamboo stake in the ground.

[00:15:55] And a lot of the existing swing arm mowers for orchards and vineyards it takes a lot of force to move that swing arm.

[00:16:03] It's been a real challenge for us. So, so we ended up having people go out with weed eaters, which is super expensive and is actually something that some vineyards do either biodynamic vineyards in the area that they'll send people out with weed eaters to go control the weeds under vine.

[00:16:17] I don't want this to be just like a hyper specialized science experiment. If we're sending people out with weed eaters, it sounds a little bit ridiculous, but there are folks in the industry that do it. So it's not. It's not that ridiculous.

[00:16:28] Craig Macmillan: It's not that ridiculous. It's legitimate.

[00:16:31] Whatever tool that you can make work, depending on the size of your vineyard and depending on what your conditions are. But yeah, you're in row mode. That's going to be an issue until these vines are mature to no doubt about that. I hope you still have a vineyard after knocking down these bamboo stakes.

[00:16:44] You don't have like real results yet. You've only just gotten started.

[00:16:47] Devin Rippner: We've only just gotten started you know, some of the results that we got were prior to our planting, there were no differences among our treatment blocks for our treatments across the site. So that's nice kind of starting at a, a pretty even baseline.

[00:17:03] We're going to track the changes over time. Honestly. I hate to speculate, we don't have the data for it yet, but we've been applying, our synthetic fertilizers based on our like compost mineralization rate. And one of the things that's pretty obvious when you walk out there is that weed competition is brutal for young vines.

[00:17:23] So where we're spraying with herbicide under the vines, there's less weed competition. Those vines are just bigger.,

[00:17:28] we're going to up the amount of fertilizer that we apply next year to try to, like, get around that. And it's one of the challenges at our site is that for long term research, we have to manage our vineyard in a way that kind of limits how many comparisons that we can make. Functionally, two out of our three rows are buffers. It just eats up an enormous amount of space and I'm, I'm hesitant to start putting other treatments into those areas. Like, oh, what if we vary the fertilizer rate to see what the effect is with relation to mowing, right?

[00:18:01] So can we get over the weed pressure by, Applying more fertilizer. One of my main takeaways is that a lot of the recommendations that you might get for like, for conventional management won't necessarily work if you're trying to change your system

[00:18:16] That's where, you know, growers are going to have to play around and understand that if they're mowing under vine, there is going to be more weed pressure and those weeds take up nitrogen.

[00:18:27] You may have to fertilize more. I mean, that, that's just a consequence of, of weed competition.

[00:18:32] Craig Macmillan: yeah, yeah, yeah. That's interesting. And in irrigation water too,

[00:18:37] Devin Rippner: Oh yeah. Yeah, for sure. Absolutely. They use a lot of water. There's no doubt about it.

[00:18:42] Craig Macmillan: Which actually brings me back to the clover. I planted crimson clover in my yard once and I irrigated it and it was really pretty and I actually put two and a half foot, three foot high risers off of my lawn sprinklers to get a sprinkler high enough that I could keep growing it. And I was able to grow it up to about three feet tall and it was gorgeous. It was absolutely amazing. But it does make me wonder if, what's a subterranean clover? It's a low growing clover, but how much effect does irrigation have on it in terms of making it taller or taller?

[00:19:13] Devin Rippner: That's a good question. I haven't looked into it that much. I consulted with some colleagues here. Who've done work with a variety of cover crops, and they were the ones that recommended the subterranean clover. It has a short stature and part of it is because of how it flowers and seeds, it can't get that tall because it's, it pushes its seeds into the ground.

[00:19:32] And so there's no real benefit for it getting taller because then it will be farther away from where it needs to put its seeds.

[00:19:39] That's a real concern. I mean, I've learned so much by , having a vineyard gophers, voles, rats, mice, they can be problematic. Right. And if you have a tall cover crop, that's getting into your vines, like that's an easy pathway up.

[00:19:52] Keeping the, those undervine weeds and cover crops short is really important.

[00:19:58] Craig Macmillan: Yeah. It's also really important for the success of your predators.

[00:20:01] Your barn nows and whatnot. They can't really do much when things are tall. So keep going, keep good luck. You're in it. You're in it now, Devon,

[00:20:09] Devin Rippner: Oh, yeah. No, that's what it feels like. I feel like I jumped into the deep end of a pool, but didn't realize it was so deep. And so, yeah, I'm learning.

[00:20:17] Craig Macmillan: Because prior to a few years back, cause you were, you were at Davis and you were at the Oakville station. Is that right? For a little while.

[00:20:24] Devin Rippner: I pulled some samples from Oakville, but no, I was mostly on main campus. I'm a soil chemist by training. Grapevines are relatively new for me. I worked for Andrew McElrone, who , does some great work a lot of my previous work did not involve grapes, and it was mainly, like, tomatoes or other annual crops, and often, like, pretty lab based stuff.

[00:20:47] And so this has been a real deep dive for me to do something different.

[00:20:53] Craig Macmillan: which is an excellent transition to some of your work which you did at other crops, but you also did some other interesting things related to vines and to soil. And that is x ray CT imagery. You were the first person to introduce me to this concept. I I had no idea I guess I should say X ray micro CT imagery. What, what are the exact terminology? What is it? What can it do? What can we learn?

[00:21:20] Devin Rippner: Thanks for bringing this up. Let me just try to keep it simple and I'll build out from there. Just like a doctor's office where you can get an X ray you can actually X ray soils. And plants and look inside of them. X ray computed tomography is where instead of just taking one x ray, maybe you take 1000 x rays as the sample is slowly moving. And what you end up with is the ability to make a three D reconstruction of that sample. Where you're able to look inside of it.

[00:21:50] Materials that absorb x rays look different than materials that don't absorb x rays. And so you're able to start Teasing apart structures that are inside of plants and soils

[00:22:01] There's different levels to that. Humans have X ray computed tomography done on them, right? You can go in and have that procedure done to look inside of you. It's very much like an MRI there are some tools that it. look at very big volumes. And then there are some tools that look at very small volumes.

[00:22:19] That's where there's the x ray microcomputed tomography is looking at very small volumes. And a lot of times those instruments they're low often located. With synchrotrons. So a synchrotron is a particle accelerator that moves electrons at about the speed of light. And then as they're going at the speed of light, , it bends them, it shifts the path of the electrons.

[00:22:43] And in doing so , Theory of relativity says that when you have a big shift , in the direction of these electrons they must lose energy. And so they lose energy as the brightest light that we know of in the known universe. And so some of that light are x rays and those x rays are very tunable, and there's a lot of them.

[00:23:03] And so we can basically focus on a really tiny area. And still have a lot of x rays. That lets us look at really small things and still have like good contrast and be able to image them relatively quickly. This field is advancing quickly. I know it sounds pretty crazy to talk about x raying soils and plants and things like that.

[00:23:23] But the reality is these x rays can also be used to identify elements. And so you can do elemental speciation. So you can be like, Oh, all of the phosphorus there is as phosphate rather than some other form or it's calcium phosphate, not magnesium phosphate. That's called x ray adsorption, near edge structures.

[00:23:42] That's how people do that. A long time ago, these instruments used to be unique. You do like a tomography and then you do like these Zains do elemental information, but those things are converging. Now it's possible to do like x ray CT and also do elemental analysis and speciation on the same sample.

[00:24:01] in 100 years, that may be how we do our soil testing is you literally have one of these instruments on the back of a tractor. You pull a soil core. You do a quick scan and you say, here's our structure. We can also see the organic matter inside of the soil column. And then by inference from the outer edge of the soil column, we can get What elements are there and what form they're in and then make predictions on their availability.

[00:24:27] Were very far from that, but that's like the vision that I have in my head is that at some point, , these will be sensors that people can just use in the field. Will they use an enormous amount of energy? Absolutely. Technology has, shifted in my lifetime and a lot of things that have seemed absurd in the past are now commonplace.

[00:24:47] Craig Macmillan: What kinds of things, and it can be other crops as well, but in particular, there was one you did with, I think, grape seeds. Those are the things that can do what, what have you actually. Zapped

[00:24:59] Devin Rippner: Yeah.

[00:24:59] Craig Macmillan: a better word.

[00:25:01] Devin Rippner: You know.

[00:25:01] Craig Macmillan: mind here. Okay. So

[00:25:03] Devin Rippner: Yeah. So I work with a lot of folks at different national labs. So the Pacific Northwest National Lab is a lab I work at a lot. And we've done a lot of imaging of soil cores and they're big soil cores. So three inches by 12 inch soil cores and to look at soil structure and we're working on segmenting out organic matter from them.

[00:25:22] That's something that was not previously possible, but with modern neural networks and deep learning, we can actually train. Neural networks to identify specific compounds in the soil and identify them. We've done it with soil columns. I've done some work with soil aggregates.

[00:25:38] So we can look at very small things as well. I've looked at grape seeds, so we had a little study where working with some folks at Davis they pulled out grape seeds, before, during and after fermentation, functionally, and we looked at how the structures of the seeds were changing.

[00:25:58] The idea here is that grapeseeds provide a lot of tannins and they're not necessarily like the best tannins for wine, but they do provide a lot of tannins.

[00:26:07] People have always wondered like, why do grapeseeds kind of supply a constant amount of tannins during the fermentation process? And as it turns out, it's because the structure of the seeds is changing during fermentation,

[00:26:18] They start cracking. And so the internal structures become more accessible during fermentation.

[00:26:23] And so that's what we were seeing using x ray tomography is these internal changes that were happening inside of the grape seeds that could potentially promote tannin extraction.

[00:26:32] Craig Macmillan: That is fascinating. That explains a lot. I'm just thinking through, Tannin management. The date currently is in the beginning of November 2024. So we're just wrapping up a harvest here in the Paso Robles, central coast area. And so I've been thinking a lot about tannin management last couple of months on behalf of my friends who make wine, not myself. That's not entirely true. Is there a practical application to that in terms of like timing or conditions or things that would contribute to the, the cracking breakdown of these seeds that you identified?

[00:27:05] Devin Rippner: We weren't able to go like that in depth and it's some, it's an area that I would like to build on. But the idea is that. The fermentation is a pretty harsh environment. You have a massive change in pH. Microbes are working hard. You have the production of ethanol, which allows the extraction of different compounds.

[00:27:24] The seeds are seemingly being modified during fermentation. There needs to be more work done in this area in terms of seed tanning management. We now have kind of a, the more physical. Explanation for why those cannons are coming out of the seeds.

[00:27:39] If you are able to pull your seeds earlier from fermentation, I mean, that's like a ridiculous thing to say, but you know,

[00:27:45] Craig Macmillan: no, I mean, winemakers are very clever there's a lot of techniques that have become more prominent, I think, in the last 10, 15 years in terms of things like pressing off early, so getting your extraction fast and then finishing out the fermentation off of skins, off of seeds, you know, that's one way that you can do it really using seed maturity as a major variable in your pick decision is another one that I've seen people really draw to.

[00:28:09] I remember people crunching on seeds and going, yeah, that's mature. Now I'm seeing people reject a pick date based on that.

[00:28:17] Like we were going to wait for these seeds to mature fully before we pull because of, because of these issues with a seed tannin. So just knowing that I think is fascinating.

[00:28:28] And if we can put some time and pH things on that, that would be really cool. Are you going to be using this technology with the with the research plot for anything?

[00:28:36] Devin Rippner: Oh, yeah. Yeah. I mean, we

[00:28:39] already have started that. We've already started down that route. Shortly after planting we collected soil cores from, , the vine row. And then from where the, the planter tires were functionally running just to look at changes in bulk density. So like kind of how compressed the soil is and then trying to get at changes in porosity.

[00:28:58] We looked at these cores relative to , a field next door. That has had very relatively little disturbance in the past, like 4 to 10 years. It's kind of variable but has had less disturbance than say, like, right after planting a vineyard mechanically. Some of the things we see are you know, when you mechanically plant a vineyard, the bulk density , in the vine row is much lower than where the tractor tires are running that intrinsically makes sense.

[00:29:26] And they're kind of both different than a place that's been no till or low disturbance for four to 10 years. Some of the things that are most interesting, and, and again, this is preliminary, it's got to go through peer review. . But when we look at the CT scans, you can actually see where worms have been moving,

[00:29:45] In these, like, low till and no till plots or this field that has just not really been disturbed.

[00:29:51] , so worms are actually making sizable holes in the ground, and those holes contribute to the porosity in these, like, low disturbance soils compared to these very disturbed soils. And that was a really interesting thing to visually see. You can see the worm castings in the scan.

[00:30:10] I don't know if you've ever seen worm castings before, but they kind of, they're these little, like, kind of football shaped Things that are all clumped together our soils don't really aggregate.

[00:30:20] We don't have enough organic matter and we don't have enough clay. And so that's like driving force behind aggregation in our soil seemingly is worm castings. For me, that was just mind blowing.

[00:30:31] I was not expecting to see that. I think I was expecting to see a lot of roots or like root channels and they're there, but the worms are like following these roots and root channels around.

[00:30:41] I'm a very visual person. And so when I do CT stuff, it's like, Oh, wow. Like I can see it with my eyes. If I can't see it with my eyes, it's hard for me to believe. But when I see it with my eyes, , it's believable.

[00:30:52] Craig Macmillan: We've done a number of interviews recently around so the microbiome and just soil biology kind of in general, , is that gonna be part of your analysis as some of these projects go forward?

[00:31:03] Devin Rippner: Yeah, absolutely. So we've done something called phospholipid fatty acid analysis.

[00:31:09] So that gives us an idea of kind of, The microbial consortium that's there right when we sample phospholipids don't really stick around in soils. They're quickly degraded. We would like to do some sequencing challenges. We don't have a microbiologist on the team. And, and so we would, we would have to pay for the sequencing.

[00:31:28] And even then sequencing is really interesting because, you could be like, oh, we did say 16 S-R-R-N-A sequencing. And that's like, that's a particular like region or a particular type of sequencing that is, that only picks up on say bacteria.

[00:31:47] Whereas if you want to see fungi, maybe you need to do something called ITS sequencing. And so unless you do like all of the sequencing, you can get an idea of what's happening to the bacterial communities or the fungal communities. But unless you do all of them, it's really hard to get a more holistic picture.

[00:32:05] And then, a lot of the sequencing that we do or is done we're missing things. If the regions analyzed aren't big enough, like we can be blind to specific things that we know are there. And so things like my understanding is that fungal mycorrhizae can actually be hard to detect by sequencing.

[00:32:21] And so even if you visually see them in the roots by staining, you may not pick them up by sequencing. It is a challenge. Now, I, you know, I think that certainly studying the microbiome and understanding its relationship , with vine performance and soil health is, is crucial and is really, you know, one of the things that it's kind of the Holy grail

[00:32:41] Craig Macmillan: Yeah.

[00:32:43] Devin Rippner: We're trying to get there.

[00:32:44] Craig Macmillan: We're trying to get there. That is definitely the message, but it also, there's definitely the potential. I think that there's a lot of people working on this. I think we're going to get there. It's, genomics is so big. I've talked to people that are like, at some point we, we, we will probably be able to get down to species, so we will know the bad actors from the good actors, we'll get a sense of what the real ecology is.

[00:33:05] That's a decade plus away still, but we're going there. Right? We're we're gonna figure it out. We're gonna figure it out at some point. We're gonna get there.

[00:33:14] Devin Rippner: Yeah, I agree. And there's, there are some techniques. There's some really cool techniques. So Jennifer Petridge at Lawrence Livermore lab does a lot Carbon 13 labeling of root exudates. So she basically gives plants, she treats them with carbon 13, enriched CO2. And then she looks at how much of the carbon 13 is then incorporated into the DNA of microbes to try to get at how well associated they are with plants.

[00:33:41] I think that work is just incredible. And there's some folks at Davis that are, are working that in that area as well. That's kind of the stuff that gets me really excited to seeing when people are trying to really tie it into what's feeding on root carbon, , who's getting these exudates, things like that.

[00:33:59] , that to me is one of the, One of the ways that we'll be able to, like, get at these questions is to, to start differentiating, the bulk soil microbiome from like the, the real rhizosphere associated microbiome.

[00:34:11] Craig Macmillan: so you got a lot going on. You got , you got a bunch of different things happening. What's the path ahead look like for you?

[00:34:17] Devin Rippner: Sure. So, and with with the soil health vineyard. I mean, I'm very excited to keep that going. We'll do another large sampling event in 2027 or 2028. We'll start making wine from our grapes. Not next year, but the year after that. So we'll be excited to see how our different management strategies influence our wine.

[00:34:40] The wines that come out of the vineyard, or the wines made, made from the grapes that come out of the vineyard. So those are some of the things , I'm most excited about with regard to the vineyard.

[00:34:50] Otherwise, I have a lot of data that I need to process and get out. That's something that's next.

[00:34:56] I, I'm collaborating with some folks from the University of Illinois in Berkeley lab to look at changes to the Moro plots in Illinois over time. So that's the oldest agricultural experiment in the United States. The plots there have been in experimental treatments for 149 years.

[00:35:15] And the reason I'm involved is because vineyards can be very long lived things, right? I mean, there are vines in California 100 years old.

[00:35:23] This is one of the few experiments to me that's like comparable to what we see in vineyards. And so I'm really curious about, you know, how do, how do management practices influence soil structure, microbiome, the metagenome, the metabolome, things like that, on these century long timelines.

[00:35:43] That to me is like some of the really interesting questions. If you have a vineyard for, for a century, or if you want a vineyard for a century, what do you need to do? How do you make that work? Knowing that it's going to take 20 years to have your vineyard be profitable.

[00:35:57] I mean, you're already on a different timescale than annual crops, right? yeah. And so it's just like, how, how do we make our, our vineyards as sustainable and long lived as possible? Because , that, that initial investment is huge. It is so much money.

[00:36:13] Craig Macmillan: I think that's really great. I think coming up with findings on other crops, but with practices that could be transferable is really great. You know, we don't need to be in our little grape silo. All the time. And in fact some of the soil microbiome stuff have been with interviews with people that had no connection to vineyards whatsoever. And it was great. The things that they were learning, they were absolutely transferable to this crop as well. That hasn't gotten that kind of attention. Grapevines are tough little suckers, really from an evolutionary standpoint, they're pretty rugged and so we can kind of get away with a lot just because of that.

[00:36:48] And now I think the margin for error is less and less, especially when we get into tougher and tougher sites like you're talking about and different conditions, especially if you've farmed it for a while and things have changed. Being able to look at other, other systems and see what's there.

[00:37:03] What is one thing that you would tell growers around this topic of research?

[00:37:09] Devin Rippner: vineyard is very informed by grower practices. We have a grower board that like helps us make decisions. A message that I will say is like science is science and science is often pretty, you know, Like straight laced and rigid because it must be. know, We're going to find things and those results hopefully will be interesting.

[00:37:27] But it's not the be all and end all . of science and research. Growers continuing to try innovative things push the boundaries of what they think is possible is really how we get progress. And I am hopeful , once this vineyard is more established to start going back out and working with growers.

[00:37:48] When I first started in Prosser, I sampled from probably 40 different vineyards around the state just to get an idea of what the soil properties were like. And we've done some, some experiments with that. Some of our results are that permanganate oxidize oxidizable carbon. So this POC C classically it's been called active carbon.

[00:38:08] There's some new research that suggests that it's, that's maybe a misnomer and it's really, often plant derived carbon.

[00:38:15] It seems like there are some effects from that, that suppress disease. And I think that , that's an area where growers can really kind of play around and see if there's , waste from their vineyard and applying it to their vines trying to look at what that does to their, POC C values and also try, just getting in trying to look at some of the past issues that those vines may have and see if there's any decreases.

[00:38:41] A lot of observational science is really important. I like hearing from growers that, yeah, I did this thing and it looks like it made a difference. There's a lot of value in that and, and I don't discount like grower knowledge in any way, shape, or form. Like it is deep knowledge growers know things that I don't, and I find that out all the time.

[00:39:02] I value those observations. They they give me guidance on how I want to do my work. And we do try to incorporate that stuff into the soil health vineyard. Over time we are going to have to figure out like, You know, can we sustain funding for a vineyard for, say, 50 years if all we're doing is like a cover crop, some compost, and then a mix?

[00:39:23] That seems like it's maybe not the most sustainable thing. Science requires that type of stuff, but it's just not that sustainable. So finding ways to make use of our, border rows and stuff like that is going to be important. And a lot of the research that we do is going to be informed by grower observations.

[00:39:39] Craig Macmillan: Yep. Yep. Exactly. Where can people find out more about you and your work?

[00:39:44] Devin Rippner: Sure. So you can look me up online. Devin Rippner a lot of stuff will pop up. There's a USDA website that has a listing of my publications and things like that. I also have a personal website. So those are some places to, to check out my work.

[00:40:00] I try to make sure that my stuff is open access and usable. So, like the deep learning code, the image segmentation code that I co developed for X ray ct work is now being applied to like other types of imaging on. So people are using it at hops and a variety of other things on.

[00:40:18] So that code is online. Like you can find it it's associated with my papers. You can play around with it and try it with your own stuff. Mhm. And, and, and that's a big thing for me is like open data. I, I love sharing a lot of the, the data that I have and the code that I have so that people can, repeat what I did.

[00:40:35] Look me up online and yeah, you'll be, you can find that, find those resources.

[00:40:40] Craig Macmillan: we will have links to a lot of that on the show page. So please visit the show page and check this stuff out. I was really happy to hear you use the word repeatability.

[00:40:49] Devin Rippner: Yeah,

[00:40:50] Craig Macmillan: Yeah. And I also was really, it's hard. it's very, very hard and it's often overlooked. You know, the, , the scientific methods we know today was all built around the idea of repeatability. That's how you demonstrate whether something's real, real, or if it's only real under certain conditions, blah, blah, blah, blah. So that's really great. I'm glad you're doing that.

[00:41:08] Well, I want to thank you for being on the podcast. This is a Devin Rippner. He is a research soil scientist with USDA agricultural research service and an adjunct position with the crop and soil science department at Washington state university. Really fun conversation, Devin, lots to think about. I will be following this closely. Or annually, probably

[00:41:31] Devin Rippner: Cool.

[00:41:31] Yeah.

[00:41:32] Craig Macmillan: these things are slow. I'm not going to be checking every week. But I just think it's really cool project and is real inspiration. And I would love to see the same kind of thing replicated in other places.

[00:41:41] Devin Rippner: Great. Thanks Craig. That was really fun.

[00:41:43] Beth Vukmanic: Thank you for listening.

[00:41:49] If you enjoyed this podcast, Vineyard Team has a couple of in field tailgate meetings coming up this year that you won't want to miss.

[00:41:56] The first is on February 20th in Paso Robles, and it is a dry farming grower around table. Now you don't need to be a dry farmer to enjoy this event. There'll be a number of different growers here talking about their experiences, trials, challenges, and successes.

[00:42:13] The second event is on March 12th, and it is Grazing as a Sustainable Practice for Vineyards, taking place in Los Olivos, and we hope to have some adorable sheep on site.

[00:42:24] Make sure you check out the show notes for links to Dev lots of research articles, plus, sustainable wine growing podcast episodes, 80. The Goldilocks principle and powdery mildew management, 90 nematode management for Washington grapes, plus a whole healthy soils playlist.

[00:42:42] Now for the fine print, the views, thoughts, and opinions expressed are the speaker's own and do not represent the views, thoughts, and opinions of the USDA ARS. As such, the views, thoughts, and opinions. Presented by the speaker do not constitute an official endorsement or approval by the United States Department of Agriculture or the Agricultural Research Service of any product or service to the exclusion of others that may be suitable. The material and information presented here is for general information purposes only.

[00:43:14] If you liked this show, do us a big favor by sharing it with a friend, subscribing, and leaving us a review. You can find all of the podcasts at vineyardteam.org/podcast. And you can reach us at podcast@vineyardteam. org.

[00:43:28] Until next time, this is Sustainable Wine Growing with the Vineyard Team.

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262: A Vineyard Research Site to Study Soil Health

Sustainable Winegrowing