Episode 42: Regenerative Viticulture
“In the winters when we have heavy rains like we’ve been having this year, a healthy soil is one that infiltrates all that water”
“If we are talking about regenerative, we are talking about the ecosystem as a whole—in the region that I’m in, the North Coast, that comes out as cover cropping and no till. If you use these together, then your goal is to improve the soil structure and soil health by the bioexudates from the different cover crops that glue the soil together into aggregates. ”
A conversation with UCCE Viticulture Advisor Dr. Chris Chen (Sonoma, Lake, Mendocino Counties) and soil scientist Noelymar Gonzalez-Maldonado (UC Davis) about regenerative viticulture, soils, and climate resilience in vineyards. Released February 24, 2023.
guests on the show
Dr. Chris Chen
Dr. Chris Chen is the University of California Cooperative Extension Integrated Vineyard Systems Advisor for Sonoma, Lake, and Mendocino Counties. Dr. Chen graduated from UC Davis with an M.S. in Viticulture and Ph.D. in Horticulture and Agronomy with specialization in Viticulture. His scientific expertise with grapevines and vineyard systems is related to abiotic stress tolerance, particularly with respect to excess heat and extended drought. Dr. Chen also has expertise in wild and cultivated grapevine rootstocks, focused on abiotic stress and salinity tolerance. Dr. Chen has researched the efficacy of shade nets as heat-damage reduction tools for wine grapes at the UC Oakville Research Station in Napa Valley and worked on numerous field-based projects across California ranging from Delano and Paso Robles to Napa, Sonoma, and Mendocino counties. Learn more on Dr. Chris Chen’s website and follow him @GrapeAdvisor.
Noelymar Gonzalez-Maldonado
Noelymar Gonzalez-Maldonado is a soil scientist and doctoral candidate in the Soil Biodiversity and Health Lab at UC Davis with an M.S. in Soil Science from The Ohio State University. She is a UC Davis Professor of the Future and Western SARE Graduate Research Grant recipient. Gonzalez-Maldonado conducts research and extension to quantify indicators related to soil health and regenerative agriculture in vineyard systems throughout the Napa, Paso Robles, and Lodi viticultural regions. Her research is comparing and contrasting concepts of soil health and tradeoffs between soil health and vineyard production in key viticultural regions across California. Her expertise is in soil ecology, health, and biodiversity with experience working in soils across the U.S. As an advocate and emerging leader in diversity, equity, and inclusion as well as science communication, Noelymar Gonzalez-Maldonado co-founded the Women in Ag Science Collective. Follow Noelymar @noelymarg.
Transcript
Mallika Nocco
Welcome to Water Talk. In today's episode we're talking about regenerative viticulture and water. Our guests are Dr. Chris Chen, a University of California Cooperative Extension Advisor for Sonoma, Lake, and Mendocino counties with expertise in grapevine heat and drought stress, as well as sustainable vineyard management. Our second guest is Noelymar Gonzalez- Maldonado, a Professors of the Future Fellow and the co-founder for Women in Ag Science, with expertise in soil health and regenerative practices across the Napa, Central Coast and Lodi regions.
So, we always try to do a wine episode every season of Water Talk. And I thought that this one would be particularly fun, just because we have some new leaders and new folks who are doing really fantastic work in the extension and research space, thinking about soils, thinking about regenerative agriculture and thinking about drought. So, we're going to be covering some regions that we haven't yet covered.
So just for a little bit of a Water Talk recap. In our last year we talked to Mark Battany, who's in the Central Coast region, and is a UC advisor in that area and has been for a long time. We had some really fun conversations with him about frost. And the year before, we spoke with Glenn McGourty, who actually was the advisor emeritus for Lake and Mendocino counties. And now Dr. Chris Chen is taking over that role, but then also adding Sonoma to that area. So, Sam, Faith, are you excited to talk more about wine and water today?
Faith Kearns
Yeah, I'm super excited to talk with Chris, who's new to UC ANR. We've got so many new people right now in UC Cooperative Extension. And so, I think slowly, but surely, maybe we'll be able to meet up with them. So, this is a great chance to do that. And always happy to talk with doctoral candidates, graduate students.
Mallika Nocco
And so, I'm so happy to have the two of you here. And we were just talking like there's a lot of emerging new leaders in viticulture and water and soil health and regenerative agriculture. So, it's really fantastic to have two of those leaders here today.
Christopher Chen
Thanks for having us.
Noelymar Gonzales Maldonado
Thanks for having us. I'm very excited to be here.
Sam Sandoval
Yeah, and Chris, Noely, super excited to have the two of you here. Chris, we have made a couple of times back in Mendocino and Sonoma. And Noely, pleasure meeting you.
So, Chris, I know that you cover actually quite a lot of wine country in California: Sonoma, Lake, and Mendocino counties for viticulture. And I would like to ask you, so how do the challenges and opportunities for grape growers differ in these regions related with water, soils, and perhaps, anything else?
Christopher Chen
Yeah, so I think one of the big misconceptions we have of the North Coast growing region is that we have plenty of water. There is enough water to grow grapes in this area, but we're still impacted by the droughts much like the rest of California is. So, we do have to consider what our water resources are and budget our water for the year for irrigation and for overhead frost protection. So, a lot of Mendocino and Sonoma County viticulture is actually irrigated with surface water. While Lake County, my third county, is irrigated with mostly groundwater. And that can pose some unique challenges in each county going into the future.
Lake County in particular which is being irrigated by groundwater should be watching their aquifers watching their water reserves. And while it may be one of the most sustainable groundwater reserves due to the annual recharge rate, it's not really immune from the water scarcity or the declining irrigation water quality in the future. So, Lake County in terms of water is unique where I work. And somewhat similar to places like Paso Robles where groundwater is the main source of irrigation water.
Soils are also really unique up here. Most of this region was kind of a forest or was a forest before it was repurposed for agriculture. For instance, Sonoma and Mendocino counties where they're centered, really along the Russian River, so they tend to have alluvial soils, clay loams, sandy loams across both counties with, of course, differences between valleys even. But again, Lake County is the oddball right with numerous soil types across the county and that's because most of the soil profiles in Lake County are the results of the still active volcano Mount Konocti.
This results in things like rose quartz boulders in the streams, obsidian boulders in the soil, which can make vineyard establishment a real pain in the butt, and other kinds of strange soil features that make it you know, easier or more difficult to farm grapes, depending on what the situation is. But it's pretty cool. And then the other thing is that most of the soils in this region are pretty high in organic matter. They're pretty good at holding water and nutrients compared with analogous growing regions across the state. So I think I think it's a very unique area. But my main point here is that we still have to worry about water pretty regularly.
Mallika Nocco
That's super interesting. I don't think I realized that about Lake County, that it was dominant groundwater used for irrigation, that's really interesting.
Christopher Chen
You would think that they would use the lake.
Mallika Nocco
Yeah, it's just it's, that's not what I expected from that area. That was surprising to me.
Sam Sandoval
Mallika there are some power dynamics there because, basically, some of the water that falls or that is the stored in Lake County is used by Yolo County downstream. And some of the water that falls in Mendocino County is mostly used by Sonoma County. So, there are also some interesting micro power dynamics of where water falls and who uses it in this small region of California.
Christopher Chen
That's, that's true. I think a lot of the water in Lake Mendocino actually ends up in Sonoma County.
Sam Sandoval
And in Marin County.
Christopher Chen
And in Marin County, right.
Mallika Nocco
I guess that's a classic California case, right? Where the water falls, and it's not necessarily used where it falls. And there's a complexity of systems governing who uses it and where it's coming from? Seems like a good moment to transition and ask Noely some questions about soil.
So, Noely, can you tell us a little bit more about what soil health is, and how you're thinking about this term for California viticulture? Like how is it different from other systems where you've done soils research? I know you did your master's work in Ohio, and you grew up in Puerto Rico. So yeah, we're just curious.
Noelymar Gonzales Maldonado
Sounds good. So very different soils. And I think one of the main challenges is, for example, here in California and the tropical regions, like Puerto Rico, it's the high soil diversity that we have. It makes it more complicated for predicting outcomes, for making recommendations, to try to get a sense of what's going to happen due to different practices. Whereas in Ohio, we still have some of those challenges, but we typically have a little bit less of the soil diversity, and it's usually a bit easier to predict these outcomes.
So, we've been studying soil health for wine grape production. One of the main challenges is that soil health has been more studied, or more intensively studied, in areas like the Midwest, like Ohio, the northeastern area of the US. Usually there we have more of grain crops, and very different system than what we have here in California. So, the goals matter and the soil types matter. This is something that we're trying to include when we're assessing soil health. In the wine grape production, especially in areas like Napa where the goals are very unique, like producing high grape quality, usually soil health is compared to soil fertility. And in some cases, growers are a bit resistant to the soil health concept because they might think it will impact the vine vigor. You know, this is something that we've been trying to study to see how can we build healthy soils in vineyards.
What we found from our interviews, we did an intensive project interviewing growers from the different areas, if we define soil health is one that is balanced, that is resilient and sustainable, the growers are more willing to work towards building healthy soils. A healthy soil is also one that, it has good infiltration and water retention. In the winters when we have heavy rains, like we've been having this year, healthy soil is one that helps infiltrate all that water. A healthy soil is one that has good but slow nutrient release, especially in terms of nitrogen. A soil that can release that nitrogen through the microorganisms and organic matter decomposition, but that is not high release that we can lose it through the irrigation. A healthy soil is one that has diverse and active organisms and that has, most importantly, organic matter, one that can build and retain that carbon.
So, when we compare it to the general definition of soil health, it's not that different but we just need to make a focus on resilience and balance its vineyard soils. We still want the soil to be to increase the organic matter. We want to protect that organic matter, a healthy soil is one that is balanced, that is resilient and that is sustainable.
Mallika Nocco
Fantastic. Chris, you have done some fascinating work looking at heat waves. Can you tell us what happens to wine grapes and wine during a heatwave? Or after a heatwave in terms of the wine? And what are some different mitigation strategies that are being used with heat waves, especially as the heat waves become more frequent and more intense?
Christopher Chen
Yeah, definitely. I'm going to go on a tangent here real quickly and say Noely just came and presented at Sonoma County Grape Day and the feedback says that she had one of the favorite talks.
So, heat waves. Yeah, heat waves are becoming more prevalent. They typically occur after veraison. And veraison is again where the grapes are starting to accumulate sugars and color anthocyanin. And so, after veraison, these grapes are starting to accumulate sugars via flow unloading, they're no longer directly fed by xylem. They're fed by phloem. And typically, this is also for the grower a great time to reduce irrigation, and implement any deficit irrigation strategies they might have, which can contribute to an increase or an improvement in the phenolic profile of the grapes due to water stress responses, and also can save water late in the season when less water is actually available for irrigation. So there's multiple benefits to these deficit irrigation strategies, which then indirectly and directly impact how the wine turns out in the end. But if a heatwave hits during this time, it can really cause problems and throw off what you could consider the chemical balance of the fruit, throw it out of whack.
So, one of the main compounds that we worry about are anthocyanins, or the color compounds in red grapes. These are probably the best example of heat related degradation of desirable compounds in grapes. So they accumulate from veraison until the grape hits somewhere between 24 and 26 brix, typically. After this peak, right around that sugar content, they start to degrade pretty rapidly due to solar radiation and heat exposure, which is why heat waves are so bad at this time of year. The berries that are left on the vine for longer than the vine really wants them on there will start experiencing degradations and anthocyanins pretty rapidly and the longer they're attached to the vine, the more you're going to see degradations in these anthocyanins.
You know, in contrast to that or, in parallel to that, titratable acidity or total acidity will also decline. Grape vines, in addition to photosynthesis also respire, like we do, they breathe. Grapes, they tend to use malic acid to respire, but they also produce it up until a certain point. So later in the season, after veraison, during this hang time period where we're leaving grapes on for a bit too long, malic acid production actually is not as much as is used during respiration. So, if it's left on the vine too long, and expose the heat waves, the vine will use up more malic acid than it can produce. And it'll decrease the total acidity of the grapes, which directly impacts how much acidity is in your wine.
Of course, we also see problems with berry dehydration and sunburn on grapes during heat events. These are the visual symptoms, the things that people see right away you see berry shriveling, and you see burn on one side of the cluster, typically, on the evening side that's exposed to the most sun throughout the day. So luckily, the grape has its own way to prevent this from happening, and that is using its canopy to shade its own fruit. Of course, you know, us being humans, we tend to manage the canopy to improve light penetration to the fruits, which can be good, especially if you're in a place that doesn't get a lot of solar radiation or accumulated heat hours.
So as an alternative to leaving more leaves on the canopy, you can use artificial means like shade netting, which is what I did my master's degree on. I looked at shade netting and how it impacts anthocyanins and acids in the grapes. And these can help reduce solar radiation and temperature in the fruiting zone and actually mitigate that anthocyanin degradation and acid losses during a heatwave event.
Now, shading is probably the best option because it's the most straightforward in my opinion, there are other options to deal with heat waves. One that we did look, I looked at with Dr. Luca Volante, who is now working at Fresno State, was using kaolin, or surround, which is a very simple clay. It's a white clay powder, and we applied this to the fruit we applied to the canopy. And what that did was actually increase the water use efficiency of the grapevine by up to 25% about. But it's relatively impractical in a production setting because you have to apply so much of it to get this effect that can reduce the impact of heat waves.
The thing that I see most often with heat waves is growers responding using irrigation. So during that time frame during the heatwave, the grapevine is going to be transpiring more. Water is going to be evaporating off of the soil surface, more especially if we reduce the canopy size artificially or by human means. So, you know, if we irrigate during this timeframe, then the amount of water can actually provide resources so the vine can transpire and cool itself during the heatwave event, so that reduces canopy temperatures by supporting transpiration. But the one I think is most exciting and you know, there's other ways to do this is shade netting, as well as shade film, which was also done in the Oakville station recently. And these are both just ways to provide artificial shade and use photo selective materials so that we get the right spectra of light that still provides what the grape needs to ripen by also limiting the incoming infrared light, so it doesn't burn.
Mallika Nocco
I have a quick follow up question. I think myself, and most of us who drink wine, I know what the flavor of acidity is. So, I have some intuitive sense for what changes in titratable acidity would do. And actually, that's something that we also measure in tomatoes. So, like I get kind of the relationship between titratable acidity and flavor. What is an anthocyanin? What do anthocyanins taste like? I know you hear anthocyanins as the healthy part of wine, like why we can all feel good about drinking it, but what flavors do they impart or when the anthocyanin content goes down? Like how does that change the way a wine tastes?
Christopher Chen
So, anthocyanins, I don't know if they have a huge impact on taste, I know the skins do have tannins in them. But the tannins are a different compound than the anthocyanins. So, you're not going to get a huge difference in mouthfeel or flavor of the wine by degradation of anthocyanins. The real impact here is that most people that buy red wines buy based on the label and the color of the wine. So, if you're going to go out and you're going to say, buy a Cabernet Sauvignon, or Zinfandel is probably a better example. Say it's a Zinfandel. And you are looking at these clear bottles, the labels are comparable you're not you know too picky about the labels, but you're looking at one of them is more of a pinkish, reddish hue and the other one is more deep purple, a lot of people will buy that deep purple one instead of the pinkish reddish one. And that changes based on the oxidation state of the anthocyanins.
So, if you have a dihydroxylated anthocyanin, you get a more reddish color in the grape, and those are less stable color compounds. When you have a more purple kind of deep, royal purple color, that's a trihydroxylated anthocyanin, and that gives you a more stable color compound that stays in the bottle. So, even if you age it, you still get that color, you've retained that color that the wine had initially. Now there's also orange colors, like in oranges. Those are monohydroxylated anthocyanins but typically we don't ever see those in grapes, occasionally, you'll see a tinge here and there. If you were to ferment those, they probably would just fall out.
That's where we get the term the color falls out of the wine when you age it. So, the less stable the anthocyanins are, the less that color is going to retain in a bottle of wine. And if you've ever opened a bottle of wine from 50 years ago, you'll notice that the color is very different than a wine that was made two years ago. For that reason.
Mallika Nocco
Yeah, that makes a lot of sense. I never really realized how much I associate color with all of these other characteristics. So, when you brought up the Zinfandel, I was like, oh, I think of those as inky. And then I think of the color together with the way it tastes and like you those oftentimes will have like a higher alcohol content. So, you got to be careful. That's super interesting.
So, Noely and Chris, I guess this question is for both of you. There's just so much attention and focus on regenerative agriculture these days. We are kind of thinking about defining regenerative agriculture for different systems, again, just like soil health. And well, I've noticed that there are more and more large corporate entities and foundations and different organizations who are very much interested in regenerative agriculture. And these groups are very interested in labeling regenerative agriculture and defining what is regenerative agriculture and what is not. And this is something that myself and many other scientists working in this space are thinking about. And I'm curious, how do you think about regenerative viticulture? Where are the knowledge gaps? What is it in what is it not? So, whoever wants to tackle that first!
Noelymar Gonzales Maldonado
I guess I can talk a little bit about regenerative agriculture. So, I see it as a group of practices that are sustainable, that are focused on the soil, especially on protecting and building soil health. Practices like no-till or reducing tillage, having a natural cover or cover crops, especially ones that are permanent, or perennial, have an integrating livestock in the vineyards, for example. These are practices that are sustainable, because they help recycle nutrients better, they help in having a more circular agriculture.
So, it might have different specifics to different people. But in general, I see it as a group of sustainable soil management practices that not just help with soil health, but also help with other ecosystem services like increasing biodiversity, being sustainable for the grower in terms of profits, of not just protecting the land and the environment, but also supporting growers economically.
These are questions that we've received throughout our research: how would practices that benefit soil health would impact the grape quality? How expensive are these going to be in the short term? And in the long term? How the combinations of these practices is really going to affect my production? So, there are many research gaps here. And this is something that many scientists here at UC Davis are currently working on trying to assess. What is regenerative agriculture for wine grape production, or grape production in general? And how do the combination of different practices influence the soil? And also the grape? Do you have anything you'd like to add, Chris?
Christopher Chen
I agree with you. 100%. I think when we're trying to define a term, we have to think about what that term means to start with. And if we're thinking regenerative, I think that's something we should approach as a whole ecosystem view. And soil is something that traditionally was overlooked in a lot of places, maybe not here in California, but in a lot of agricultural regions, soil health and soil capacity to grow more in the future, that was overlooked a lot. So, I think if we're talking about regenerative, we're talking about the ecosystem as a whole.
In the region that I am in, in the north coast, that comes out as cover cropping, and no till. And if you use these in conjunction, your goal here is to improve the soil structure, and the soil health by the bioexudates from the different cover crops that's kind of glued the soil particles together into aggregates. And that's great. I think it's fantastic. But we also have to think about what cover crops we're using, we have to think about what are the best practices for the practices that we're calling regenerative. Grasses are great for erosion control; legumes are good for nitrogen fixing. If we want beneficial insects, putting a pollinator row in is really beneficial. And if our goal is to build better soil structure, or aggregate stability, we don't want to go breaking up all the work we've done with cover crops or all the work that cover crops have done with a disking pass. And in combination cover crops and no till with compost applications, we can actually improve the soil health or regenerate it.
In terms of gaps in the knowledge, it seems like the really the effects or impacts of different cover crops is what's lacking, from my experience, from what I've seen. We want to be able to say, planting this mix, this specific mix of cover crops will result in this outcome. But we don't know the exact impact of each species, particularly when they're planted in a mix and interacting with one another. White mustard is a really good example of this. White mustard has been shown to mitigate the spread of certain kinds of nematodes, but only one it's in a sort of monoculture cover crop situation. Those benefits of reducing nematode spread actually disappear when white mustard is planted with other crop species. And we need to know stuff like that as we're going forward with different regenerative practices, whether it be focused on soil or cultural practices.
Faith Kearns
Chris, that's a really great lead into our next question, which is about drought. And it seems like basically, since you've started, we've been in a drought period. This year is a little bit up in the air. But I'm just wondering how you've been advising growers during drought? And what are some of the most common questions and concerns that growers have for you about drought?
Christopher Chen
Yeah, like I said, at the top of the podcast that we still have to worry about water use in the north coast. We don't have all the water in the world. But I think one of the biggest concerns that we have, that a lot of other places don't, is using overhead irrigation for frost protection and spring. Typically, you know a wine grape vineyard only needs about six tenths of an acre foot per acre of water per year to meet irrigation requirements. And most growers I've worked with are not really concerned about having that much water, or enough water to actually get a decent crop. Unless they have to frost protect with overhead irrigation early in the year.
So, the real main alternative to overhead frost protection is implementing wind machines or frost fans. What my colleague Mark Battany has really made a point of saying is that they don't work everywhere. Wind machines cannot work for frost protection everywhere. But where they do work, they can save, you know, one to five acre feet per year, depending on the size of your vineyard, that would have otherwise gone to frost protection. And in a drought, that's pretty substantial. That's a lot of water. So, we need to identify where these wind machines are going to work. And you know, where they’re actually efficient for frost protection.
Mark Battany my colleague, again, he has a great program for testing regions for wind machine efficacy with using temperature towers to measure temperature inversions in spring or autumn, which is fantastic. And I think, you know, there's a lot of regions that could use that. There's a lot of regions that could say, well, we want to use less water, but we don't know if this investment of 10s of 1000s of dollars in a wind machine is actually going to pay off. So, we need to know that and spending a few 100 bucks to know that before you put out a very expensive machine that requires maintenance and fuel is really important.
Another big item is soil water dynamics and irrigation management strategies. I think one big thing that I mentioned was that our soil types change a lot from place to place. That hugely impacts how we're going to manage it. So, if the soil’s field capacity is really less than what water is being applied for irrigation events, so it can't actually hold all the water you're putting on, then that grower is basically losing that water, it's leaching past the root zone, you're not going to get it where you want it to go in the grapevine. And that can be a good thing, especially if you have a lot of salts in the soil, if you leach a little bit that's ideal, then the roots of your grapevine aren't salt impacted.
But knowing your soils can really inform you about how much to irrigate at a given time. So, in one event, and for how long, so you can avoid those water losses and increase the efficiency of your irrigation strategies. And I, especially when designing a vineyard and putting in an irrigation system, that's what I try to promote with the growers I work with. I want them to maybe not put in one gallon per hour emitters on either side of the grapevine. Maybe their soils can't handle that much flux. So, I asked, would you be willing to do a half gallon per hour emitter? I think that's a pretty reasonable approach. And if it saves them water and makes it more efficient in the process of irrigation, then that's just the on the ground, ready to go approach that we can all look at.
Mallika Nocco
So, Chris, I just want to clarify because it was in the middle of what you said. But with wine grapes, it's six tenths of an acre foot of actual water use that's going to evapotranspiration, but between one and five acre feet that are going to frost protection in your area. Is that right?
Christopher Chen
So, the one to five acre feet is not per acre, that's just going to be depending on the size of your vineyard. And that's the average of what I've seen for different vineyards. The six tenths of an acre foot per acre is by the acre. So, if you have a 10-acre block of grape vines, that's going to be six acre feet of water per vineyard where you would be using maybe two acre feet of water for frost protection. But what that does is it drains their reserves, it drains their ponds. And if they can't refill it after a certain time, which is the case and most of where I work, then that water is just gone. And the alternative is losing the crop for the year to frost damage.
Mallika Nocco
Yeah, I mean, the biophysicist in me also thinks about the regenerative systems and that concept like just the idea of reducing the albedo of those systems, using cover cropping, and trying to warm them up. Or thinking about just how different regenerative practices might change the energy budgets of those systems could potentially also save some water.
So, Noely, you are doing intensive interviews and soil sampling across three iconic California regions Napa, the Central Coast in Paso Robles, and Lodi. What do you think these areas have in common related to soils and water and what has been different? And I know you're doing both interviews and sampling, which is kind of a unique way to think about this.
Noelymar Gonzales Maldonado
So, we're doing intensive interviews. The reason why we're doing these interviews is that we thought to really understand soil health, we needed to go and talk with the pros, the growers, the ones that are in the field every day. So, something that I've seen in common across these regions is that there are three main concerns when growers think about soil health for vineyards.
First is water requirements. How do different regenerative soil management practices might influence the water requirements in the vineyard? And the water dynamics, like "Am I got to have the good infiltration I need? Am I going to have the good water retention I need?" depending on the different practices.
Another thing that we've noticed is concerns about grape quality or yields. Especially grape quality for regions like Napa, and then quality and yields for Paso Robles, and more yields for the Lodi area. There are concerns about how different practices might influence the outcomes. Because like they say to me, after all, this is a business, so how can we be stewards of the land but also achieve our production goals? In terms of quality, or yields, or both.
And then the third is concerns about costs. Many growers think that doing practices that build healthy soils would increase the costs or might have some increase in costs in different ways in terms of labor, or in terms of getting a new equipment or having to apply more product like composts, and things like that. So, across these interviews, we've been able to identify what are some concerns, what are some barriers in terms of the adoption of regenerative soil management practices.
And some of the differences that we've noticed are the goals and those goals drive the soil management decisions. And then another big difference is the access to water. Like Chris was talking earlier, different regions obtain the water in different ways. In Napa, they use surface water, but then in regions like Paso Robles they use groundwater. Access to water, how much water they're going to be using, these are very different in the different regions. So that's something that makes studying soil health and also regenerative agriculture challenging across this region.
The main message we've gotten is that growers are willing to adopt regenerative soil management practices, if more practical information is provided. If they can obtain information of, "Oh, if I do no till and this type of cover crops..." like what Chris was mentioning before, "...if I do these practices, these are the outcomes I'm going to get." And that is something that we are also trying to study during my dissertation project. We are sampling the soils, we are assessing soil health in these different regions, can we come up with some ranges of different values of different indicators that can help growers have some expectations, like realistic expectations? Increasing soil health, or improving organic matter for building healthy soils is not a linear process. And not all soils have the same capacities.
So, what can we do to maximize the soil health for our given soil with its given capacities? That's something that we're trying to work on and that growers among all these regions have been strongly interested in learning more about.
Sam Sandoval
So, Noely, follow up question: Is there a difference between the thinking of a farmer between these kinds of immediate short terms that might be some of the practices? And compare with those that are kind of medium long term? Because I can see that some of these medium long terms might be also economically beneficial. But I'm not sure, what has been your discussions with farmers there?
Noelymar Gonzales Maldonado
I have had those concerns about how fast the outcomes would be. Some growers do these practices, regardless of how long or short term the benefits would be. It's part of their vision of their vineyard or of their wine. Whereas some other growers really need the information so that they can make the decisions. For example, some growers will tell me how long would it take for me to build organic matter? They would ask me that. And there are some concerns about if soil is really going to improve within the years I have of farming, right? When we talk, what I like to discuss with growers is that soil health is a journey. Soil health is a journey. So, it's something that will benefit you in the long term. It might take several years to build, to develop, to get protected, but I've had some very contrasting opinions or attitudes towards how much it will take for me to build a healthy soil.
And it is something we think about, but I think that this presents an opportunity for us to do more outreach, to talk more about soils so that growers can have realistic expectations. So that they know beforehand, if you're going to do these practices, they might take 10 years to see the increase in organic matter. That might be discouraging. But what I like to also say is, if you're not building it, you're losing it. So, you know, building organic matter, which is one of the main things we do for building healthy soils, is essential for the many ecosystem services as soils provide. And if you are not working towards building it, and you're losing it, that might result in detrimental effects in your soil, and your production, because they are linked. I like to explain it as a long-term investment. It's something that you might not see the benefits right away. But you are working slowly towards protecting your vines in the long term and your production.
Faith Kearns
Okay, thank you. So, Chris, you touched a little bit on heat waves earlier. And I'm wondering how both of you are seeing the effects of climate change in terms of California vineyards? I don't know if it's affecting maybe the types of wines we might be drinking in the future? Or Noely, maybe talking a little bit about the way that growers are thinking about climate change? If that's part of the work that you're doing. So, I'd love to hear from both of you about what you think about climate change in vineyards.
Christopher Chen
Honestly, I think it will start seeing changes in cultivars that are grown in each region. Many areas are getting hotter, or you know, accumulating more heat hours throughout the year. And that really impacts what grapes can be grown there to meet the highest standards or the standards that the winemakers want. Pinot Noir is a really good example, which is considered a colder region cultivar.
In regions where it's prevalently grown right now, like the region I work in, it might be advantageous to consider something like Cabernet Sauvignon soon, which performs better in warmer climates than Pinots do. However, there's a lot of areas that are, “tied to specific cultivars” and have built their reputation of the region or of their AVA based on one or two varieties. So, the speed at which planting acreage changes is going to depend a lot on consumer demand and consumer knowledge about what alternatives there are to their favorite Cabernet Sauvignon out there or their favorite Pinot Noir.
In the past, there have been cycles of boom and bust for different cultivars. Most famously, I'd say the 2004 film Sideways made Merlot much, much less popular than it ever was before the release of that film. And, you know, people are saying it's making a comeback now. But that's a 20-year gap of a loss of consumer preference for Merlot. So, people that planted Merlot in 2004. They were stuck with it for a while. Other examples might be like Muscat wines, they were very popular for a while or White Zinfandel, which is more style than a grape.
So, in the future, I think we're probably going to start seeing shorter growing seasons typically kept on each end by frost events. So, we would have to have something that breaks bud a little bit later, and something that that same vine would have to ripen earlier than the ones that we grow now. So that balance is really hard to get finding something that has late bud break and ripens quickly to match the shortening of the growing season that we're starting to see in a lot of places might be something like Sauvignon Blanc or Carignan. I'm a big fan of Chianti wines. So, if anyone wants to start making Chaintis, I'm very happy to test them out.
Noelymar Gonzales Maldonado
And in terms of the soil, I think that if we don't act now in doing regenerative soil management practices that benefit functions like soil services, like good infiltration, water retention, things like that. We've been experiencing recently with the heavy rains just flooded vineyards, that can have detrimental impacts in in the vines and the grapes. And when it comes to the drier regions, when it gets warmer in the summer, during the growing season, we might be stressing the vines more than necessary. And that also might result in losses.
So, climate change is just making the different climatic conditions more extreme. So, if we don't have a resilient soil, one that can hold all those changes, that can fight those changes, then it's really going to affect the vine health and the production, in general. That's why I always say, I keep repeating, building healthy soils is an investment. The climate is changing, and that's a fact. How can we manage so that we can protect our vines while managing the soil more sustainably. It's an option.
Christopher Chen
I'd like to just add to that that, with grape vines there's a buffer between what we harvest the vine that we harvest in the soil and that's the root stock. Just picking different cultivars is great, it can help you time your harvest better to match the changing climates. But to Noely's point about soils being very important and kind of the forefront of adapting to climate change and climate adaptive viticulture, we also need to pick root stocks that can get as much as they can out of the soil. So, if we're seeing less rains, maybe we want a root stock that has more shallow root systems so I can pick up spoon fed amounts of water that we put on it. Maybe we want a deeper root sock that we're going to dry farm. But all of that comes down to how healthy is your soil?
Mallika Nocco
I'm so glad you brought up rootstocks, I've just been continually had my mind blown by just the power and like the Sci Fi dreaming of different types of root stocks and the crops that I work in like thinking about wine grapes, thinking about almonds, and just how important these root stocks are.
Chris, have you heard anything about a root stock, or any root stocks on the horizon, that can tolerate enough water stress to do dry farming? That can tolerate flooding? Anything like that?
Christopher Chen
Yeah. So, you know, most of the rootstocks that we have today for grapes come from, I call them the big three, which I think I stole from Andy Walker, who was my advisor, but their parent material is one of these three wild grape vines or cultivated grape vines, I guess they are now. Riparia, Vitis riparia, Vitis rupestris and Vitis berlandieri. And they're all used for different things. And when you cross them, you get the offspring of them, whatever that cross is, has different traits have different characteristics. So, we have rootstocks that can do a lot of what you just said, drought tolerance, searching for water being more adaptable in a situation where they're grown in, you know, basically a desert. But what we're looking for then is to avoid rootstocks that in, at least in California, is to avoid rootstocks that are high water demanding rootstocks, things typically with riparian in the background. Riparia as the name suggests, was found near a stream, a riparian stream, and it needs a lot of water. And most of the offspring of riparia regardless of the other parent need a lot of water as well.
So, we're looking at the existing rootstocks, there are things like 1103 P, and 110 R, 1103 Paulson and 110 Richter, that they are really good at tolerating drought stress, and part of that is due to their root’s architecture. So, the difference in shallow rooting systems versus deep rooting systems is really important when we're thinking about water adaptation and water resilience in a grapevine. These tend to have both shallow and deep, so you get the best of both worlds here. There are other problems with them. But in terms of abiotic stress tolerance, there's nothing that I know of that's coming out. We do have the GRN series that was made by Andy Walker's lab, and they are more for biotic resistance of nematodes and fan leaf disease.
Sam Sandoval
Hey, thanks, Chris. Thanks, Noelymar. And one of the things here so also thank you for painting a very nice picture of a what the regenerative agriculture, and sharing a lot of the nuances of agriculture and all the different parts. I do believe that agriculture is part of the solution to climate change. And, again, if all of us have breakfast, all of us value agriculture. So, is there anything else that you want to add that the audience should know? How can we help to support your efforts?
Noelymar Gonzales Maldonado
Well, if anyone wants to learn more about the work that we're doing, you can check out our lab’s website. You can Google Dr. Lazcano at UC Davis, and you'll see, it'll take you directly to our lab’s website. And also, if you would like to see some of the efforts I've been doing in science communication, and highlighting Women in Agriculture, you can check on my website, which is womeninagscience.org. And it’s a collective, we have to support minorities in agricultural sciences.
Mallika Nocco
Can you tell us a little bit more about Women in Agricultural Sciences?
Noelymar Gonzales Maldonado
So of course, Women in Ag Science is collective as a group, we are working on becoming a nonprofit organization, and it highlights women in different fields of Agricultural Sciences. So, in our website, you'll see interviews of different scientists doing awesome work to advance sustainability in agriculture.
We interview women in the agricultural sciences to make the work visible to share so that everyone can learn about all the awesome work that they're doing. And we're also trying to create more role models for girls, for example. So, it's a diversity, equity and inclusion effort that we are working on independently to raise awareness of the different issues that women go through. And also, to highlight all the awesome work that they do.
Mallika Nocco
Awesome. Thank you for sharing that. Chris. How about you? How can the listeners of water talk support your work?
Christopher Chen
Yeah, so I work in extension. So, you know, if you're in the area in the North Coast region come to my events, I would love to have more people coming to my events we are hosting in the center in Sonoma County. We're hosting master classes every few months, which is fantastic. We have a Grape Day annually. And there are events in Mendocino and Lake counties as well.
You can also see my webpage, it's UCCE North Coast Viticulture. There's a bunch of resources on there for growers and people that, even if you just want to start growing grapes in your backyard, you got to know how to do it right. So, there's resources on there. And you want to donate there's a donate button too, to support the research programs.
Mallika Nocco
So, Noely, Chris. Thanks again for joining us today and talking grapes, talking wine, talking soils, talking climate. Appreciate you both.