Want to practice regenerative agriculture? Daniel Rath, Agricultural Soil Carbon Scientist at Natural Resources Defense Council recommends that you start by asking what you want to regenerate. Beneficial practices including integrating livestock, crop rotations, cover cropping, minimizing tillage, increasing diversity, improving soil health, adding organic matter, and reducing external inputs will vary site to site.

A long-term study found that these practices improved above and below ground biodiversity, increased water storage and infiltration, bolstered resilience to climate change, increased carbon and organic matter storage, and, impressively improved human health.

Listen to the end to learn how soil metagenomics has the potential to not only tell us what is living in the soil but how the organisms interact.

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Transcript

[00:00:00] Craig Macmillan: Our guest today is Daniel Rath. He is a soil scientist with the Natural Resources Defense Council. And today we're going to be talking about regenerative agriculture. Thanks for being on the podcast, Daniel.

[00:00:10] Daniel Rath: Thanks a lot, Craig. I'm excited to be here.

[00:00:13] Craig Macmillan: We've been trying to find folks to talk about regenerative agriculture because it's a real buzzword right now.

[00:00:18] And it's a buzzword in the vineyard industry, but it's not vineyard specific. This is applying to all sectors of agriculture and globally. This is a big concept now. So that's inspiring and drawing a lot of people, uh, in different directions. But I get different definitions of it. What regenerative agriculture?

[00:00:37] Daniel Rath: Well, first of all, I'll say it's not really surprising that you get a different definition depending on who you talk to because, you know, regenerative agriculture really hasn't been like very specifically defined yet the way I think about it. Part of the reason it's so hard to define is that it's really more of a philosophy and an approach to land management.

[00:00:59] And so, you know, it's taking into acknowledgement the fact that agricultural systems have this complexity. And instead of trying to reduce that complexity, we lean into it. We see what advantages we can get from it. It's a holistic approach. You know, it doesn't just necessarily focus on the environmental impacts, but what are the social impacts?

[00:01:18] What are the economic impacts of agricultural systems? Looking at things like local food systems and connecting farmers to consumers, but also how do we increase soil health? How do we reduce pests and diseases? It's funny. You should bring it up now. The state of California. Just finished a process in of defining regenerative agriculture for their legislative effort.

[00:01:40] Craig Macmillan: Oh

[00:01:41] Daniel Rath: Yeah, there's a draft definition out there have been numerous listening sessions The next one is on august 22nd, but I was part of that committee that tried to like Capture this sort of like ephemeral philosophy and like nail it down without hopefully killing it.

[00:01:57] Craig Macmillan: Uh, and to put a timestamp, the date of this interview is August of 2024.

[00:02:03] So this is new to that point. We'll see how that develops from here. Which is pretty cool, but no, I was not aware of that. That's pretty, pretty interesting. What are some of the specific practices somebody might use? So, philosophically, I'm in alignment. I want to build and protect my soil. I want to protect my community.

[00:02:20] I want to have healthier plants. What are some of the techniques that folks are using around the world to do this?

[00:02:26] Daniel Rath: Well, I will answer your question with a saying that my PhD advisor used to tell me every time I walked into her office, which was that, you know, what is your goal? What is the question that you're trying to ask, right?

[00:02:37] Part of the reason that regenerative agriculture does not have one set definition is that it's going to look very different. different depending on where you are. A regenerative agricultural system in a place that is facing a lot of restrictions on water, low soil organic matter, the practices you use there are going to look very different than say if you have regenerative agriculture in a place that has regular rainfall, has a lot of soil organic matter, very active soils.

[00:03:02] I would say that some of the most commonly mentioned practices are things like integrating livestock into perennial systems, cover crops, crop rotation, increasing the diversity on farm systems, reducing tillage, basically all of these practices that increase soil health, because really increasing soil health is at the the core of what it means to sort of regenerate a plot of land.

[00:03:29] But if you're talking about specific practices, you kind of have to think like, well, what am I trying to regenerate? What are the goals that I want to get out of it? One other interesting topic is the idea of reducing external inputs, not eliminating them entirely, but reducing dependence on things like fertilizers and pesticides, seeing how a that can result in cost savings for farmers, but also Relying on the natural complexity of the system to provide those benefits.

[00:03:58] Craig Macmillan: Yeah, that's always been one of the tenants of sustainable farming is to reduce the number of off farm inputs and reduce the number of farm outputs other than the crop, and that includes things like pollution, erosion, whatever, um, and try to develop a system that's stable in and of itself. Um, and it sounds like there's some things that can contribute to that.

[00:04:18] Um, what about composting? That's another popular topic.

[00:04:21] Daniel Rath: Composting, I forgot to mention that composting really adding organic matter to the soil. A lot of the systems that we've developed over the last few decades are very focused on adding nitrogen, which is important. Nitrogen is a really big limiting nutrient, but we've learned that adding nitrogen on its own is not enough.

[00:04:38] You have to add carbon in there. You have to add other micronutrients that might not be contained in your typical fertilizer mixture. And so yeah, adding compost is a really great way adding organic matter residue crop.

[00:04:53] Craig Macmillan: Again, the inclusion of animals seems to be, um, pretty consistent across different definitions, including mobile cropping systems.

[00:05:00] In permanent crops that can be a little tricky. So like in vineyards, I have heard of folks that were grazing goats and sheep in season for the most part. Folks will plant a cover crop in the winter and then maybe they'll come through with some sheep or some goats in the springtime. I guess my question is, when I read other things and they talk about having animals as part of the system, I see like herds of cattle, which are generating a lot of manure.

[00:05:25] And I can go, yeah, I, I bet that's doing a lot, but your smaller ruminants, in your opinion, I mean, can they contribute enough in a, in a, a seasonal, uh, past to, to make a difference?

[00:05:39] Daniel Rath: Yeah, this, that's a really good point. I think the short answer is, yeah, I think they do. And so the example you gave is, I think the one I would have used, right, is that planting cover crops in between these sort of like, vines that are there for a long time, and then using ruminants to terminate those cover crops and to convert it into manure and urine, which was a great source of nitrogen.

[00:06:00] When I was at UC Davis doing my PhD, we had a couple experiments on sheep terminating cover crops and goats terminating cover crops. And you could see the benefits in the soil, as long as you had those like livestock ruminants being on the plot.

[00:06:15] Craig Macmillan: That leads to another question. You know, I've got the philosophy now.

[00:06:19] I believe in the philosophy. I believe that I can actually improve the soils. One of the things I've always been a little suspicious of with regenerative agriculture is the idea of regeneration. I have a hard time kind of making sense of that in my mind in agricultural systems because things are leaving.

[00:06:36] And certain crops are not big miners. Wine grapes are kind of famous for not really mining the soil that much and they can grow in very poor soils Doesn't mean you don't want to build those soils, but if I'm looking to detect what we would call regeneration, what kinds of Variables might I be looking at and what are the kinds of things that I might actually be able to get some metrics on?

[00:07:00] Where I can say yes, this program seems to be working This is making a difference or I'm not seeing the results that I would like Maybe I should make a shift and try something different

[00:07:09] Daniel Rath: Yeah, that's also a really good question. So I think there are actually two really interesting questions in what you just said.

[00:07:15] The first one is, what do you measure? And again, it depends on your question, but very often the things that we will measure will be things like soil organic matter, right? We will be looking at measurements such as nutrient balance. So how much nitrogen is soil's organic matter, what are the nitrate and phosphorus levels in the soil for wine grapes?

[00:07:36] I know you don't want it to be like too fertile because it is good to stress those grapes out a little bit to get a high quality product. You look at things like drainage and water storage. If you see better infiltration on plots, if you don't see water ponding quite as much. One thing that is becoming more common is tracking microbial indicators, right?

[00:07:56] And so part of the reason that we do that is that microbes are like early indicators. They will change faster than the soil organic matter content. And so they can give you an idea of where you're headed and whether or not it's a direction you want to be heading in. I can, you know, apply to stuff like pest and disease too.

[00:08:15] Craig Macmillan: This is a great one because I've been working on this for the last couple of years. What am I looking for? I, uh, there's a bunch of different tests that you can do. There's a bunch of different things you can look at. If I'm trying to get a sense of what's happening with the cell microbiome, what kind of testing might I be interested in doing?

[00:08:30] What kinds of things might I specifically be looking for?

[00:08:34] Daniel Rath: There have been a lot of advances in the last, you know, decade or so looking at this. One of the biggest areas that there have been advancements is tracking the incidence of pests and diseases, right? And so, you know, that is a really good one. If you're worried or, you know, concerned about a specific pest, there are often really good methods to test for that.

[00:08:52] You can also be looking at biological tests that look at functions of interest. So say your goal is to reduce nitrogen application on your plot. There are measurements that you can make of nitrogen release from organic matter by microbes and that will give you a really good idea or, you know, a fairly good idea of maybe how much nitrogen this soil is already supplying.

[00:09:17] California is also really interested in this. So another thing, there's a soil biodiversity report that came out about a year ago in which the CDFA asked us this very question. They were like, if we were going to measure soil biology across California for a number of different purposes, what would we do?

[00:09:32] We had 15 scientists that have really been working on this for a long time. We all sat down and like, how do we capture the thought process and thinking that goes into this? into selecting the right microbial indicator because there are a lot of them and they're not all easy to interpret.

[00:09:47] Craig Macmillan: Are those recommendations out there now?

[00:09:49] Daniel Rath: I would say the, the report is out and in the report we, you, we have a couple examples. We're really hoping that the California Department of Food and Ag will sort of expand on those recommendations for more like, sort of like a targeted approach. Really what we did is we used that nitrogen example as an example.

[00:10:10] It's like this is how you would do it, but really the devil is in the details. What is the specific area you're looking at? What is like the question you're looking to answer? The biodiverse report has at least like the thought process, what are the things you should be looking for?

[00:10:25] Craig Macmillan: So we've been talking about kind of like more short term.

[00:10:27] What about long term? You have some experience, I believe, in long term agricultural research. Like, I think you did a study that was like a 25 year retrospective, if you will, of the health of a particular farm. In the long term, in the longer range, What kinds of benefits should we expect? We've talked about pest and disease resistance, maybe water status.

[00:10:51] What kinds of slow changes might we be looking for that we might see that would give us some confidence that this is working?

[00:10:58] Daniel Rath: Sure. I mean, this is an example of why long term experiments are so great because. They're the only really way for us to get at this question. But you can expect things like improved biodiversity on, um, especially above ground biodiversity, below ground biodiversity.

[00:11:15] That is a process that takes a long time. You can see things like improved water storage, improved water infiltration. You can see You know, if you're talking about the ultimate long term metric resilience, right, how do our agricultural systems respond to the climate changes that are already occurring and, you know, building that resilience means relying on this like complex biological network that really sustains our plants right now.

[00:11:46] Increased carbon and organic matter storage is another really good one. And so, you know, over time you see all of these environmental benefits and along with that comes social benefits. We see improved human health. We see improved connectivity between farms and the communities nearby. Improved sort of farm worker health and safety.

[00:12:07] All of these things are a little bit longer term, but they are all one of some of the goals and some of the benefits we see from regenerative systems.

[00:12:16] Craig Macmillan: I want to drop back to one of the practices because I've talked about this quite a bit with folks. I want to get your take on it. No till or minimal till.

[00:12:24] Or, uh, I talked to one person that said, uh, avoid excessive tillage. And the question that came back was, what the heck is that? What's excessive? You know, what, if I drag the disc through here one time, is that excessive? And this may apply to other crops that you've worked with. What role does tillage have in this process, in these systems?

[00:12:45] Because one school of thought that I'm familiar with is, okay, we grow these cover crops, we terminate them with sheep, it's great, but we may still want to incorporate that material into the soil. So that it breaks down and gets in there. Then there's another school of thought that says, No, don't do that.

[00:13:03] Don't touch it. Leave it alone. Let the system do what it normally does. And then there's a third school of thought that's like, well, I can't do that forever. Floors get too bumpy. Um, things need to be reset. Or I need to plant cover crops. So I need to set a seed bed. And again, you can draw from other cropping systems on this.

[00:13:21] What is your feelings about the effect of tillage on the soil microbiome and soil health discrimination?

[00:13:26] Daniel Rath: No, no till has been a really hot topic for quite a while. It came about when the NRCS was first started looking to reduce the impacts of a dust bowl and realizing that tillage was over tillage was a major cause of that.

[00:13:41] And so when you are looking at no tillage, there are very clear benefits. There's increased plant root presence, decreased erosion, better soil structure formation, a potential for better infiltration. But you have to wear that against the. benefits of tillage. I mean, it has very clear benefits too. It helps to keep weed and pest populations under control.

[00:14:03] It makes it a little bit easier, especially in annual cropping systems for roots to establish. Like you said precisely, it's a better way for incorporating organic matter into the soil. My point of view is that I think tillage is a valuable tool in the farmer's toolbox, right? And that what is over tillage is going to really depend on where you are.

[00:14:24] If you're on a slope, probably less tillage is better because again, you don't want that top soil to be washed off. If you're on sort of like a flat plain and you know, you know, you're tilling to establish a crop, then it's probably not a big deal to have one or two tillage passes, at least from the erosion standpoint.

[00:14:41] What we do know is that no till has also been recommended as a way to increase soil carbon. There's still, I think, a little bit of back and forth on that. At least we have seen is that no till increases soil carbon at the top. Part of the soil really doesn't increase at the bottom. So it's more of a redistribution of carbon again There are really clear benefits to tillage and you know There's a reason that people have been doing it for a long time

[00:15:07] Craig Macmillan: kind of what I'm hearing I think this is a really great message is it's another tool.

[00:15:11] It's a tool that we don't have to throw away But it is one that we should think about how we use it. I've, I've actually started to think about tillage the same way I think about, uh, pesticides and fertilizers. Where it's, it's a question of what benefit am I going to get from this? Do I need to do it?

[00:15:28] Are there other things that I could do? And then you put that all into your calculator in your brain and, and try to sort it out. And I've had some very interesting conversations as how different people kind of sorted those things out. So I think that's a great point. That leads me to another question that I just thought of.

[00:15:42] And so the role of synthetic fertilizers, for instance. The synthetic fertilizers have been pointed to, and I think accurately so, as driving land degradation in many cases, especially the overuse of nitrate based fertilizers. You also have environmental impacts in terms of pollution, potentially. Is there a role for conventional fertilizers in regenerative agriculture?

[00:16:05] Daniel Rath: Yeah, well, that's a real hot button topic there. Yeah.

[00:16:10] Craig Macmillan: Hey, we go, we go for deep water on the show. Inquiring minds want to know. Hey,

[00:16:16] Daniel Rath: that's, that's a real good question. Honestly, that's a question that I has been taking up a lot of my professional time recently. Like you said, it's not a secret. We are seeing a lot of negative environmental impacts from Over application of fertilizers that includes nitrate pollution in groundwater that applies to pesticides as well.

[00:16:36] You know neonic pesticides have had major problems with insect populations. I think that exactly What you said you need to sort of weigh the costs and benefits Of these like particular practices and you know In my work in my phd talking to farmers the sort of farmer calculus that occurs in like You know, in the minds of the folks that I work with is so complex.

[00:17:00] There are so many factors that you have to balance. One thing to be aware of is that we are applying too much nitrogen fertilizer now, and that's pretty clear from like the negative environmental impacts that we've seen. And so it's less of an idea of like. Like how do we eliminate nitrogen fertilizer and more like how do we make sure that that fertilizer gets into the plant?

[00:17:23] You know, how do we match that fertilizer application to what the plant actually needs instead of over applying, right? How do we keep it on the plot? Because it is expensive. No one wants it to be running off into the environment,

[00:17:36] Craig Macmillan: right?

[00:17:37] Daniel Rath: One of the things that has really come across to us is when we talk to folks about nitrogen fertilizer application, there are yield benefits, but very often it's also a risk management strategy.

[00:17:50] You want to apply enough nitrogen fertilizer so that if conditions are ideal, you can take advantage of them. Really and truly, there have got to be better, less environmentally intensive solutions. impactful risk management strategies. You know, that includes looking at the way that we incentivize crops, looking at the way that we handle crop insurance, looking at the crop choices.

[00:18:13] If you're in a area that has a lot of potential for agricultural runoff, it may be better to grow crops that do not require as much nitrogen, corn is very greedy, or to put systems in place that reduce that nitrogen runoff, cover cropping, riparian buffers, All of these things are like great ideas to get to the underlying goal, which is reducing the need for nitrogen fertilizer.

[00:18:39] Craig Macmillan: That's perfect. Gosh, we just keep getting more variables, don't we?

[00:18:42] Daniel Rath: Oh my gosh, I assure you that's

[00:18:46] Craig Macmillan: And speaking of more variables, I want to switch topics now. This is great, background graded by some regenerative agriculture. I know that I now have a better sense of what the philosophy and the practices are.

[00:18:56] However, you've also worked in the area of soil metagenomics and metagenomes. And this has come up in other interviews that I've done around soil health with soil microbiologists. What is soil microgenomics and where are we at and where are we going and what can we do with this and what's all the exciting stuff coming down the pipeline?

[00:19:19] But first of all, what, what is it?

[00:19:21] Daniel Rath: When you talk about soil metagenomics, in a teaspoon of soil, I'm sure you've heard the statistics somewhere, right? In a teaspoon of soil, there's like a billion microbes and like so much fungal hyphae. And inside each one of those cells is DNA. That are basically the instructions for life for those different cells.

[00:19:40] What we do in soil metagenomics is that you extract the DNA from a soil sample. And then the most complex, insane puzzle you've ever seen. We try to reassemble them, right? Right. And so like that is only possible because of the advances we've made in computing over the last few decades. And I get, you know, the national labs have really like pushes forward.

[00:20:03] You need a really powerful supercomputer to do it. Once you've done that, you have this sort of unprecedented ability to glimpse what is happening in the soil at a scale that we've never been able to before. And so that's part of the reason that people are really excited about it is because it gives us a window into like this.

[00:20:24] previously unknown black box of how microbes work and interact in the soil. I worked on that during my PhD at UC Davis, looking at like how metagenomes changed in farming systems over 25 years.

[00:20:37] Craig Macmillan: So I have always been looking for the work that I do, looking for what are the variables that I can measure and what's going to give me a number that's going to tell me what's going on.

[00:20:46] At one point I hit upon soil respiration, and I was talking to a soil ecologist and she said, well that's fine, but that tells you how much life is there, but it doesn't tell you whether it's good guys or bad guys. And then dove in to a whole nother level of, Oh yeah, I hadn't thought about, oh yeah, you're right.

[00:21:05] Oh, and then those guys prey on those guys, and then this happens over here. Oh wow, yeah, you're right. And then I got kind of hooked on the um, The Haney test, which is, I think, kind of falling out of fashion now, which again, people were throwing rocks at that, you know, and I think that when Haney first came up with that, that was something, it was like, we need something, and it would prove to be useful, I think, but I don't think that's as popular or gives us the kind of dimension that we really need anymore, at least that's what I'm told.

[00:21:34] With metagenomics, we're going to be able to tell not simply quantities, but we're going to be able to tell possibly down to the level of genus, maybe even species of who's, who's down there, which could be really, really important because like pseudomonas, for instance, there's certain pseudomonas that are, um, pathogenic and there's others that are beneficial.

[00:21:56] And so we kind of need to figure out who's who and what's what is, is that on the horizon? Maybe it's 10 years out or more, but is that on the horizon?

[00:22:04] Daniel Rath: Probably a little further out than that. A

[00:22:06] Craig Macmillan: little further out? Okay.

[00:22:07] Daniel Rath: I'll try and give you an example here. So, one of the things that we get when we pull out all this DNA is we get sort of relative abundances of different types of organisms, right?

[00:22:18] It's sometimes quite difficult to get to the absolute abundance of organisms because We're really looking at, like, proportions of DNA, but that doesn't really tell you, like, are there, like, massive amounts of this organism present in the soil. You just have a relative idea. When it comes to metagenomics, there's a lot of promise in being able to say, Oh, look, we've seen these genes that, like, allow you to fix nitrogen.

[00:22:43] And we found these genes that are associated with these, like, pests. And that's a really good idea, a really good indicator of, like, But there's another level to it. And that's really, I think what one of the like exciting parts is, is that it's not just the genetic potential that matters. It's the interactions between organisms that is quite hard to pull out.

[00:23:05] So to your example, you could have pseudomonas, you could have quite high levels of pseudomonas. Do you have a. predator that keeps those pseudomonas populations under control, right? Because if you do, then you might not be seeing a lot of disease, like presence in the soil, even though you have like relatively high amounts of it.

[00:23:25] And so understanding these interactions is sort of the next level in actually getting practical, actionable information out of these metagenomes. And we're, we're still. Teasing that apart. So really, when I talk about metagenomes, it's about potential. What is the potential for things to happen? But it does not actually mean that is what is going to happen.

[00:23:46] Craig Macmillan: Right, exactly. And so the commercialization of this technology is quite a ways out.

[00:23:51] Daniel Rath: Yeah. I mean, there are companies that are working on it right now. Again, this, it's a, this innovation is really, we're going to need to like be iterating towards success here, but really a lot more sort of research and work is required, especially on these interactions, thinking about like how they fit together.

[00:24:10] And I personally think that it's a useful indicator. I've given a talk on these like. Soil test before the real power hard part comes when you're trying to interpret right when you have a scale that says like based on these abundances There's X percent chance that you will have a disease or X percent chance that you will be able to cycle nitrogen better That's really hard to like say at this point in my opinion,

[00:24:35] Craig Macmillan: right?

[00:24:35] Right. Well, at least we're moving in the right direction. I think

[00:24:37] Daniel Rath: we absolutely are and honestly The, the best thing to compare metagenome test is your own soil five years ago. It gives you an unprecedented look into how your soil has changed and progressed depending on whatever practices you've applied.

[00:24:51] Craig Macmillan: Right, right. Going back to regenerative agriculture, is there one thing, piece of advice, idea, one thing that you would like growers to take away on this topic?

[00:25:02] Daniel Rath: Yeah, I think that one main thing is that this is not just about one specific environmental impact. This is about thinking about how we farm, how we grow food, what is our relationship To both farm ecosystems and agricultural ecosystems.

[00:25:21] You know, I think there's this idea that natural ecosystems and agricultural ecosystems, they cannot coexist. And I think that over time we're starting to see that maybe that's not true. We can encourage biodiversity. We can encourage sort of these complex natural processes on farms. And indeed they make the farms more resilient.

[00:25:41] more productive, we get more benefits from that. And so just in a way that like natural ecosystems evolve, I think that farming systems are also evolving and growing. And to us, regenerative agriculture is about bringing all farmers, no matter where they are, along on this journey towards sort of more sustainable, environmentally safe agro ecosystems.

[00:26:05] Craig Macmillan: That's exactly the word I was going to use, is uh, is we think more about an agroecosystem as part of a much larger system, um, which is what ecology is kind of all about. We can look at the ecology of a pond, but then we can also look at what role that pond plays in the forest, and we can look at how the forest plays in the landscape and we can just keep going depending on what level you want to do it at.

[00:26:27] And I think looking at our farms as part of a larger ecological system and an ecological system in and of itself also I think is a huge philosophical move. Absolutely right. Where can people find out more about you?

[00:26:39] Daniel Rath: The NRDC website is a great place to start. We have a number of different resources. We published a report on regenerative agriculture where we interviewed farmers from across the U S at least for California specific stuff.

[00:26:50] The California department of food and agriculture, again, is, has this regenerative agriculture definition process that's being carried out. As of this date in August, 2024, I also have a personal website that I update infrequently.

[00:27:04] Craig Macmillan: Well, there's something on there. Yeah. So, yeah, and if you can share those links with us, that would be fantastic.

[00:27:10] Our guest today has been Daniel Rath. He is a soil scientist with the Natural Resources Defense Council. Thanks for being on the podcast, Daniel.

[00:27:18] Daniel Rath: Hey, absolutely. It's been quite a pleasure, Craig.

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253: Regenerative Agriculture: The Path the Climate Change Resilience?

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