A Very Exciting Time for Soil Health with Dr. Tarah Sullivan


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For questions or comments, contact Dr. Tarah Sullivan directly via email at t.sullivan@wsu.edu.

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Episode Transcription:

Drew Lyon: Hello. Welcome to the WSU Wheat Beat podcast. I’m your host, Drew Lyon, and I want to thank you for joining me as we explore the world of small grains production and research at Washington State University. In each episode, I speak with researchers WSU and the USDA-ARS to provide you with insights into the latest research on wheat and barley production. If you enjoy the WSU Wheat Beat podcast do us a favor and subscribe on iTunes or your favorite podcasting app and leave us a review while you’re there so others can find the show too.

[ Music ]

Drew Lyon: My guest today is Dr. Tarah Sullivan. Tarah is a soil microbiologist from the Department of Crop and Social Sciences at Washington State University. The last time we had Dr. Sullivan speak with us, she shared some details about cover cropping and soil health in Concord grape vineyards, improving soil health, and agricultural sustainability. Most recently, her lab has been comparing wheat varieties and an emerging oilseed crop. Pennycress for their impact on microbial soil health teams. It seems we’ve been hearing a lot about soil health these days, but I thought it might be a good idea to really dove into what soil health is and how growers can build soil health. So, besides her active research lab, Tarah also teaches about soil plant-microbe interactions and engages in outreach to increase understanding of soils, soil health, and soil stewardship. She’s here today as the first part of a three-part series on soil health in Washington State and the Soil Health Initiative, with more information coming soon from Chad Kruger and Chris Benedict about the initiative itself. Hello, Tarah

Dr. Tarah Sullivan: Hi, Drew.

Drew Lyon: So, soil health. We get a lot of interest in that topic at the Small Grains website and in a lot of our programming. So tell me from the perspective of a soil microbiologist, what’s so different about soil health from some other familiar terms like soil fertility and soil quality?

Dr. Tarah Sullivan: So as a soil microbiologist, I do see every surface as teaming with microorganisms and especially the soils. So this is particularly an exciting time when soil health is coming into the public awareness, recognizing that soils are living and that they are not only habitat for microorganisms, but we can treat them as living biological entities. And what’s different from some of the concepts that have been discussed for a very long time, like soil fertility and soil quality, has a lot to do with not only the limitation of the term the previous terms but the exclusion of this biological component in many cases. So I should probably clarify that there’s often a difference in the way that scientists perceive these terms versus the way that growers and practitioners view these terms. And I’m sure you’re aware of that. But as a scientist, when I think about soil fertility, I typically — and I teach about soil fertility as really strictly looking at those nutrients that are available for plant growth, and even more specifically for crop yield. When I think about a soil fertility trial, the ultimate variable is crop yield. So how much nutrient do we need to apply? How much nutrient is available to that plant to give us the best yield? And so oftentimes that’s looking at one growing season. I know there are a lot of other factors involved, but it’s even particularly very interesting that I was able to speak with a grower last week, particularly about growing pennycress. And when we were discussing all the agronomics, the question was, “what soil fertility do I need to put down?” And that actually stunned me for just a moment, because I think of fertility as this broad thing about how do we manage the nutrients. And very specifically, the question was how much nitrogen, phosphorus, and potassium do I need to put down? And so that’s a very restricted viewpoint of soils, right. As just what inputs we need to make the yield happen. When we move on to something like soil quality, and a lot of times, historically speaking, we realized soil quality became a term and came into the public awareness when we also started talking about things like air quality and water quality. And so these things were all tied together. And so it did link this idea of the function of the soil, not only just managed in managed ecosystems, but also in natural ecosystems. But it was still really focused on the needs of humans. Right. Human health and human habitation. It was nice that it started to incorporate these ideas of the physical and the chemical qualities. So not just nutrients, but all the physical qualities of the soil as well. And it incorporated both the inherent and the dynamic qualities of the soil. And by inherent, I mean, those factors, the things we can’t necessarily control, like texture, parent material, depth of the soil, those would be the inherent properties of the soil. But it also included dynamic properties of the soil. So the things we could change, things like organic matter, nutrient holding capacity, and the management of the soil would often control those dynamic factors. So we have soil fertility strictly looking at nutrients and crop yield. We moved on to sort of this idea of soil quality is a little more holistic and thinking about all these different aspects of soil. But then we’ve moved now into this era of soil health that very dramatically emphasizes biology. And so the three different areas of soil health include all those previous ideas, but also really emphasized biology. And so we look at soil health as incorporating some very important ideas that haven’t necessarily been incorporated in those previous terms, like the fact that it’s a nonrenewable resource. So by that, I mean, you can lose an inch or a centimeter of topsoil in a given growing season, depending on your system. And we can’t rebuild that inch or that centimeter of soil for thousands of years. So, therefore, it’s a nonrenewable resource and we need to start treating it that way. But also, it incorporates soil health, incorporates the idea that it is of a vital living ecosystem. And we also saw this advent of the term soil health start to come into the vernacular around the same time that we started to recognize the importance of the microbiome. So all the microorganisms in human health as well. So we have this parallel between soil health and human health. And in human health, there’s been a huge revelation in understanding how microorganisms not only react to the human ecosystem but actually can control it in many ways. And so we see that being true in soils as well, and especially in the interaction of plants with soils and their associated microbiome. There was a book out in 2016 by Ed Young called, “I Contain Multitudes”, not the Bob Dylan song, but the actual Ed Young book. [ laughter ] And he has this fantastic quote where he’s actually talking about the human ecosystem. But we can apply it to soils as well. And the quote goes like this. “I think it’s more accurate to see the human immune system as a team of rangers in charge of a national park. As ecosystem managers, they must carefully control the numbers of resident species and expel problematic invaders. But here’s the twist. The creatures of the park hired the Rangers in the first place. They taught their guardians which species to care for and which to evict. And they’re constantly producing chemicals that affect how alert and responsive the Rangers are. The immune system isn’t just a means of controlling microbes. It is at least partly controlled by the microbes. It’s yet another route through which our multitudes preserve our bodies.”

Drew Lyon: Yeah, that’s very good. Yeah. And I actually think this the connection between human health and soil health is very understandable to the nonagricultural community. So when you can make that connection, I think light bulbs go on for some.

Dr. Tarah Sullivan: Right. Exactly. And so we have this connection between not just the physical component of the soil, but the chemical and biological component and a real emphasis there, which is why it’s so exciting for me as a soil microbiologist.

Drew Lyon: So as we think about soil health and the soil health initiative in Washington, what are what do you see as some of the biggest challenges to soil health in the state of Washington?

Dr. Tarah Sullivan: Now, that is a really big question, and as you’re aware, Washington State is one of the most diverse states in terms of soils and cropping systems. We actually have representation of all 10 of the 12 soil orders that actually exist in the world represented in Washington state. And we know that soil classification is a huge driving factor in how the soil responds to management. And so in terms of management, we also have hugely diverse cropping systems across the state. We have as much crop diversity as any other state in the United States except California. And so as we think about the problems and the challenges facing soil health, it gets to be a little bit of a challenge to even define the biggest problem areas in Washington state because you have that interaction of soil type with management and the particular agronomic activities that are happening. But if you go to the Washington State Soil Health Initiative and you look into what we’ve been able to identify as six broad categories that are challenges across the state. We’ve been able to identify compaction, erosion, nutrient imbalances, acidification, pests and pathogens, and salinity and sodicity as the six top problems that are facing producers, but in general affecting soil health across the state right now. And if you do go to the website, you can click on each one of those challenges and find out more about the research that’s being done and ways to address those challenges and potentially build up your soil health in that area.

Drew Lyon: Okay, well, be sure to put a link to that in our show notes. So if a grower understanding that soil health isn’t totally understood yet, if a grower wants to build or improve soil health, what would you what would some general recommendations be?

Dr. Tarah Sullivan: That is another great question because it’s also one of those things that’s viewed very differently from the scientific perspective than it is from a producer perspective. So when I am teaching about soil health in class, when I do outreach or education or extension activities, I tend to talk about, number one, decreasing erosion. That’s one of the things that seems to be a very accessible idea for most of the growers and producers and even younger children that I work with and things like that. Also, increasing soil carbon and soil organic matter. What’s a little challenging about that is, again, soil texture and soil type have a huge impact on whether you can even build soil organic matter over a human time span, right? We can talk about trying to do that over geological time. And I could get into and I often do. How important microbial communities are in storing carbon in soils, and so that can have a big impact on how soil carbon moves through soils. And sometimes practices can involve decreasing tillage. Sometimes that’s not an option. Depends on your cropping system. Sometimes it can also involve increasing or introducing livestock into the system. You do want to try to maintain a neutral pH whenever possible, reduce compaction and increase plant species diversity. And so really what it boils down to, especially for me, is to keep the soil microbes happy. They need food, they need shelter. And organic matter is often the key to both of those factors. But if a grower or a producer were to potentially Google something like. “what can I do to improve my soil health?” They will often find resources that discuss either the four or the five principles of soil health and depending on which resource you’re looking at. The fifth one is often introducing livestock because that can be the most difficult for many growers. But the other four include maintain biodiversity. So that can be either introducing cover crops, changing your rotation, using different cultivars, or anything like that. You also want to maintain soil cover. So decreasing soil disturbance. Like I said if you can decrease tillage, great. If you can’t, that may not be an option. But try to minimize soil disturbance whenever possible. Maximize soil cover. Try to keep something over the top of the soil at all times. Again, integrating livestock if you can, but also trying to maintain continual living roots as long as you possibly can, because those plant roots are a huge source of carbon, both shelter and food for microorganisms.

Drew Lyon: Hm. Okay, those all sound like good ideas, maybe a little easier to say than to put in practice, depending on where you are in the like, but — so a growing plant out there is better than dead residue protecting the soil, but dead residues, better than nothing out in the soil.

Dr. Tarah Sullivan: Right, exactly. And a lot of these concepts and that’s why I kind of mentioned that if you Google it, you’ll find these concepts out there. But ultimately, a lot of these things still need to be tested rigorously, empirically tested in many different systems. Like I said, across Washington state, we need to test out the various different recommendations that are accepted in the, you know, the public eye right now and really be able to analyze how those impacts soil health in order to make real recommendations.

Drew Lyon: And as you said earlier, the intrinsic nature of the particular soil you’re working within the environment has a huge influence on that. So you really do have a lot of places you have to test these disparate things and get the answer.

Dr. Tarah Sullivan: Yeah, exactly right.

Drew Lyon: Okay. Quite a challenge, but it’s really a very exciting field. I know it’s one that growers are very, very interested in and not just growers. So besides some of the more traditional extension activities that we do, what are some other forms of outreach that you’ve been involved in lately?

Dr. Tarah Sullivan: Right. So it’s a very exciting time for soil health. And so microbiology right now, and even I could go as far as to say to be a soil scientist. It’s exciting right now. And I don’t traditionally have a lot of extension activities as a part of my usual. But I’ve been involved right now with the Washington State Soil Health Initiative as a part of the leadership team. And so by doing that, I’m actually able to interact with ranchers and farmers and even foresters who are establishing some long-term sites to really start to examine some of these questions. And so that’s a lot of interaction that I wouldn’t normally be able to do. But what I’m really kind of most excited about right now is that I’m working with elementary education. So we’re really focusing on second through sixth-grade children and trying to raise awareness of soil health and soil stewardship and even just awareness of soils, to be honest. That typically doesn’t enter into a person’s, you know, system of thinking even about the environment. We have great systems for increasing awareness of water quality and air quality and climate change in some schooling systems, but we don’t have much in terms of soil health, soil contamination, and soil awareness. And so I’m really excited to say that I’ve started working through the Soil Health Initiative with elementary education. I’ve started partnering with the Palouse Discovery Science Center. So it’s a science exhibit hall focused on children and children’s education. And with them, I’ve been able to donate a vermicomposting bin where the children get to play with the worms. And we talk about how composting works and how important organic matter is. I’ll be working on developing a few lessons for their Earth Explorers after-school program where small children get to play in the soil and they get to feel the texture and potentially paint with soils and learn about how important soil is and soil biodiversity is. And we’re doing both indoor and outdoor exhibits. So you can actually look for a full exhibit come sometime next spring. So spring of ‘22. In addition to that, I’m working with elementary educators on a pilot program, in part because of the pandemic, I’m not able to go into classrooms right now. And so I’m working with second through sixth grade again, providing these kits of soils educational tools for teachers to work with. So that would include books focused on soil biodiversity, online, reading resources, and activity resources, but also hands-on exercises and activities all directed towards soils, soil biodiversity, and soil health. So I’m very excited about that right now.

Drew Lyon: That is very exciting. So if somebody if one of our listeners is interested in learning more about that, where can they go to find more information to contact you directly? Or do you have a website or what’s the avenue there right now?

Dr. Tarah Sullivan: Contacting me directly is the best way to do it. I’m working with a very limited group of teachers in the Pohlman School District, but also with the Colville Tribe Extension Unit and some teachers in that system to see sort of pilot how these work. Also experimenting on my own kids, see if they like how this works, and then expanding out from there. So if there’s interest, feel free to contact me directly and I can help provide a kit of educational tools.

Drew Lyon: We’ll put your contact information in the show notes as well. Very interesting stuff. It’s just a whole new world out there with our ability to understand and start to understand what’s going on in that very complex world we know as soil. Thanks very much, Tarah.

Dr. Tarah Sullivan: Thank you, Drew.

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Drew Lyon: Thanks for joining us and listening to the WSU Wheat Beat podcast. If you like what you hear don’t forget to subscribe and leave a review on iTunes or your favorite podcasting app. If you have questions or topics, you’d like to hear on future episodes please email me at drew.lyon — that’s lyon@wsu.edu –(drew.lyon@wsu.edu). You can find us online at smallgrains.wsu.edu and on Facebook and Twitter @WSUSmallGrains. The WSU Wheat Beat podcast is a production of CAHNRS Communications and the College of Agricultural, Human and Natural Resource Sciences at Washington State University. I’m Drew Lyon, we’ll see you next time.

The views, thoughts, and opinions expressed by guests of this podcast are their own and does not imply Washington State University’s endorsement.