Why water makes plants happy when it matters most is under review by Brian Hornbuckle

Market to Market | Podcast
Apr 11, 2023 | 36 min

To better understand the success of a plant - it is better to know the stressors and factors that make that corn plant grow in various times of water supply. Dr. Brian Hornbuckle is working with NASA to find when corn does best in the field. 


Paul Yeager: Hey everybody, it's Paul Yeager This is the MtoM Show podcast a production of Iowa PBS, and the Market to Market TV show. We're going to class today we're getting to the end of the semester on the university campuses. But that doesn't mean learning can stop. We're about to start planting in the Corn Belt. And we're going to learn a little bit more about some science going on right now. To better help us understand what is going on in the fields how much water is not just in the ground, but in the plant. And what are we losing in that plant? When the sun and the dry weather come out? Dr. Brian Hornbuckle is at Iowa State University in Ames, Iowa, we're going to have a conversation about a new NASA grant that he earned. And he is going to see if he can help seek and spot crops stress from space. Crop stress is, well it's important to your bottom line, and how you market the crop. So this science is a way to understand marketing, and the marketing understanding the crop science so we're going to kind of do a little mixing. Have fun. Enjoy this installment of the M to M Show podcast. Brian, no matter how many times I look up, Shenandoah, I still struggle to spell it. When did you first learn how to spell your hometowns name correctly?

Brian Hornbuckle: don't know. But when I was in college, I met someone that was from Shenandoah, in Pennsylvania. So I thought that was interesting. And I think it's spelled the same way. So I can't tell you when I first learned to spell it, but I do know there's another similarly spelled name shenana. Hola.

Paul Yeager: Now, that is a fun trivia question. I don't think I want to see either name and the prompter. Yeah, against each other to know which one is which. So tell me about your life in Shenandoah, Southwest Iowa. What were you doing there before you went to college?

Brian Hornbuckle: Oh, I was growing up and had a great time. And Shenandoah was part of a church there and had a sister and a mom and a dad. And I also had a lot of other family there that lived on what we called the farm, which was about six miles south of town. It was farmed by my uncle, my mom's brother. And he inherited it from his dad, who had died suddenly of a heart attack when my mom was in about fourth or fifth grade. And my uncle was just finishing at what was then Tarkio College in Missouri, it's not there anymore, but that's where he was going to school to learn about agronomy. And so I would go out to the farm. Once in a while often after Sunday, church service, we go out and eat and just be with each other. I didn't do a lot of farm things. I was a town boy. The main thing that I did in high school was that I was involved in lots of different activities. And that's one of the advantages of being in a small town like that you get to sample lots of things. I was in band and clean the marching band and jazz band and concert band. And then I was playing sports basically year round. In the fall, I was running cross country. In the winter, I was playing basketball. In the spring I was running track. And maybe for one or two years, I played a little baseball, which is interesting, because when I was really a lot younger, not super young, but when I was in elementary school baseball was probably the biggest part of my life. And one of the things I remember is my dad coming home after work, and we'd go out in the backyard, and we would play catch, and that turned into I would pitch to him. And that was a big thing for us for a while until I got involved in other things. And the one thing that got me into running, which was what I did the most of in when I was younger, was I was playing a pickup game of football one afternoon when I was in seventh grade. And I twisted my knee really bad. And so that ended my football career, which was good because the one football game I played. I did a lot of arm tackling and wasn't very good. And so then in my football career, but that started me running after I was healed. And I had a very interesting running career. My high school cross country team eventually won two state championships in class three a I believe and we also eventually had a very good track team too. And so I ran a lot of distance races in track and had a wonderful cross country team, the best team that I've ever been on in my life in terms of selflessness, and wanting to do everything that they could to see the team succeed.

Paul Yeager: So what's your athletics is what took you to brown? Or was it all academic?

Brian Hornbuckle: Yeah, so I got to my senior year, and I wanted to challenge myself both academically and athletically. And so I applied and was accepted at five different schools. One was Bates College in Maine, another one was Swarthmore College in Philadelphia. Another one was Grinnell College and here in Iowa, and all three of those were division three schools, very good academically. But division three, and I wanted to really see if I could do it at the division one level. And so that meant, it came down to two of the other schools I applied to one was Iowa State University. And the other was brown, and I applied to brown, just on a whim, I got a pre application in the mail one day, which I suspect was directed to me by a guidance counselor or something like that. And I thought, What the heck, I'm not ever gonna go there, but I might as well fill out the pre AP and see what happens. So I sent it in. And then the full application came, and I thought, well, I'm never gonna go there by my eyes will fill it out. And I got accepted. And I had to choose between Iowa State and brown. And I felt really good about Iowa State, except for the fact that, at that time, I don't know if you are a cross country fan or not. Bill Bergen was in his prime here at Iowa State, this had been the late 80s and early 90s. And just about that time was when Iowa State won two national championships in cross country. And so I came to visit and realize that, you know, I'd be running but I wouldn't be doing a lot of competing with all the stellar athletes they had here at the time. So I thought, well, let's try this brown thing and see if it will work or not. And so I made a visit. And it was a long ways away. But I thought that I could always come back if it didn't work out. So I made the jump and I tried it and it worked out fantastically, and I was able to really test myself both athletically and academically.

Paul Yeager: Well, it's not often that the Ivy League school is the fallback. It was for you. The cross country course at Iowa State Yes, I am familiar a little bit with cross country, I have a son that runs it. So we go up to the Iowa State meet or the, the, the course there across the street from the old Research Farm, you're in the middle of doing research you you've been in Michigan, as well as Mississippi. Now you're at Iowa State, agronomy and science kind of coming together. It sounds like you're getting to mix everything in that background that you talked about. In those areas. There's plenty of farmers, if you could see the picture behind me. It's a cornfield. What is it about the science of agriculture that gets you excited?

Brian Hornbuckle: That's a great, I'm glad you asked that. So if you would have told me when I was in high school, that I would have been an agronomist, I wouldn't be doing what I'm doing right now. And that's laughing because I never thought about that as being very interesting. I was very lucky to have wonderful science and math teachers in high school. And I became interested in engineering because that's how I felt like at best combine those two types of things, science and math. And so I was staying in Brown made sense, because they both had engineering schools. So I started doing that. And I found out that I liked electrical engineering the most. And I kept going in that direction. And I took a class my sophomore year in college, and it was the, well, let's say I wasn't prepared for it. I was sitting in the front row. And the professor said, All right, everybody in this class that hasn't taken this certain math course raise your hand, and I raised my hand and looked behind me and no one else was raised. in your hand, and so I knew that I was going to have to work pretty hard in that class to be successful. Turns out, it was a class on electromagnetic theory. And that is one of my favorite things right now. And so it was getting time to go to graduate school. And in the meantime, also in high school, I should backtrack a little bit. I spent a month working for the National Park Service through an organization called the Student Conservation Association. And I spent a month on our royal, which is a national park in Lake Superior. It's, it's an island and Lake Superior. It's about 10 by 40 miles. And I spent a month there, renovating a campsite. And through that experience, I realized that I really liked working outdoors a lot. And I also wanted to do something that would help preserve the environment so that other people can enjoy it, too. So here I am. Thinking about graduate school, I guess another part of the story is when I was in college, my first college class, I had a super enthusiastic professor. And at that point, I knew I wanted to be like him when I grew up. That's what I wanted to do. So I knew to be able to be a university professor, I needed to go to graduate school. And so here I am, going into graduate school, well, what am I going to study? Well, I know that I really like electrical engineering, especially electromagnetics study of electricity and magnetism. I know that I really liked the environment, and I want to do some kind of research that would help maintain our environment. And that's about all I knew. And I went to interview at University of Michigan, which is where I ended up going to graduate school. And the first person I talked to there, I said, Well, he asked me, Well, what do you want to study? And I said, Well, I don't really know. I really like electromagnetics. And I really liked the environment. And he said, You ever heard of remote sensing? And I said, No, tell me about it. And basically, what remote sensing is, is it's using this electromagnetic theory to study the environment. And the way we use electromagnetic theory to do it, is by using things like cameras that measure the light coming from Earth. And this light could be the light that you and I see with our eyes, or it could be light, or electromagnetic radiation is a generic term that we can't see like radio waves, like the things that your cell phone uses. Or it could be infrared light that we often use to measure someone's temperature. So that was exactly what I wanted to do. I wanted to use electro magnetics to study the environment. And that was remote sensing. Okay, so now we're getting to the farm part. So I joined a group there that does this type of remote sensing. And I needed to decide what am I going to do for my graduate project, my dissertation. And we were very interested in how we might be able to measure water in soil from space from a satellite that was carrying a special type of camera that can see a special type of light that we call microwaves. And it turns out that Earth's surface looks very dark when it's wet. In other words, when there's a lot of water in the soil, the Earth looks dark. And when the Earth's surface is dry, it looks very bright. And so essentially, what we can do is we can use a special camera that's on a satellite orbiting the Earth. It's looking at these special types of radiation we call microwaves. And if we see a bright signal, that means it's pretty dry. And if we see a dark signal, it means it's pretty wet. Now that's, you know, simplifying it quite a bit. But essentially, that's, that's the physics. The problem is, is that there are other things that contain water that's in between the soil in our satellite. One, there's some water in the atmosphere, but it turns out at this special type of light, we don't have to worry about that. So we can forget about water in the atmosphere, including rain. But the thing that we really have to worry about is water in plants, water and vegetation water in crops. And at that time, we were still trying to learn how to remove that influence from the sea. Now that we're measuring in space, how can we get rid of this water in crops signal to figure out how much water there was in the soil. And so the simplest way to start looking at this problem is to find a situation that's fairly simple to analyze. Now, it's really not that simple. But we started out by looking at a cornfield that was really nice and homogeneous and uniform. So we can make some assumptions about what we're looking at. And you know, cornfield is planted in rows. So it's fairly easy to walk through, I can put instruments in the ground pretty easily, I can cut down plants and find how much water is in the plants. So we looked for a farmer in southeastern Michigan that would be willing to let us put our instruments in his field, and do our experiments. And we found one, it was a wonderful field, the farmer was fantastic. And I did this experiment. And in during that experience, I started thinking about well, agriculture is pretty cool, because humans are deciding what to plant, when to plant and where to plant. And because of my other training in or science, that was interesting for two reasons. Number one, because you know, the plants are there to provide us with either food feed fiber, or fuel. We call those the F's of agronomy. But they're also doing something else. They're also putting water back into the atmosphere, when they grow when we call it transpiration. And this water going back into the atmosphere has a big effect on our weather and climate. And so this is pretty always, oh, keep going. And this is pretty interesting. Because, again, humans are deciding where to put these plants. And so in, in essence, humans are, in some ways, changing the weather and climate by putting plants in certain places at certain times, during the year. Go ahead.

Paul Yeager: Well, when you think about it, in that sense, then yes, humans are in charge of the leading to the biggest things of climate change. Oh, boy, here come the letters now. But your What year is this, you're doing this research in Michigan. So

Brian Hornbuckle: this is in the the mid to late 90s, early 2000s. 

Paul Yeager: And so at that point, how I want to, I want to just quickly peel off the, the academic side of this, at what point is business interested in what you're doing? Because we hear about satellite technology monitoring things in real time and fields. But at what point did the research you're doing there leap over from academics in the business?

Brian Hornbuckle: Well, it's not quite there yet. The research that I'm doing, it's still exploratory in the sense that, since that time, that it became interested in using remote sensing to look at crops. Since that time, there have been two satellites that have been launched one by the European Space Agency, and one by NASA, the European Space Agency, one was launched in about 2010, NASA, this was launched in about 2015. And these satellites, satellites are exploratory in the sense that they're not like the satellites that you see on the weather at night, we would call those satellites operational, in the sense that we understand what we're seeing when we use those satellites. And now we're ready to use that to make decisions and particularly business decisions. The satellites that I work with, we're still in that exploratory phase, but we're starting to crossover into the research, or sorry, not in the research and the business phase. So we've had some time now to show that what these satellites are measuring really can tell us about water in soil. And so they're beginning to be incorporated these measurements into some applications. The European satellite is now being used by the Europeans in their weather and climate forecasting system. And they have found that it has improved weather and climate forecasts. The NASA approved the forecast That's right, so we've been able to better predict weather and climate by using this information because of what it can tell us about water coming from the soil and going back into the atmosphere. That's what we can learn from these measurements essentially.

Paul Yeager: Well, I didn't know about this as a farm kid myself for a number of years of, if it's dry, it's much harder to rain which, because there the soil is, if it's a drought, there's no water in that soil to be I, I know I'm going to grossly oversimplify this sucked up into the atmosphere and create rain. When did we learn that fact, maybe that was a, that's an early science fact that I'm just showing my lack of knowledge here.

Brian Hornbuckle: Yeah, we call that precipitation recycling, the idea that water in the soil evaporates, now it's in the atmosphere, and later, it can condense in rain back down on us. And that would be what we would call a positive feedback. In other words, the wetter the soil gets, then we would expect more rain. And if the soil gets drier, we would expect less rain. So that there's this relationship between water and soil and water in the atmosphere. That's not true everywhere. It turns out that some places, there is this positive feedback, relationship between soil moisture, and precipitation or rain. Some places there's a negative feedback, it's the opposite, that as soils are drier, then we tend to expect more rain. And the reason why is it because it has to do with where is this water coming from that's primarily making up the rain. And here in the Midwest, that water is primarily coming from the Gulf of Mexico. So it's water that's evaporated from the Gulf of Mexico, and then brought here by the atmosphere, to the Midwest. And then so moisture plays this role of either kind of helping the rain to happen, or kind of hurting the rain to happen. So it's, it's more complicated than this, this idea of water in the soil going in the atmosphere and later raining down on us. There's more to it from that, and it changes from place to place. And those are some of the things that we're still trying to trying to learn more about so that we can do a better job of forecasting the weather.

Paul Yeager: Tell me about this NASA partnership. It's not your first time working with them. But this specific understanding the stress that a plant is having. Where does that where did the idea to move forward on this come from? 

Brian Hornbuckle: Yes. Okay. So in the last about decade, about last 10 years, I and my research group has have become really interested in looking at not just the water in the soil, but also looking at this water in plants that I talked about earlier. And up until this time, our whole goal was to get rid of this water in the plants, because we wanted to see the water in the soil. But in the last 10 years or so we've realized that this water in the plants in the crops could also be useful in telling us about what's going on with the plants. And so we've done some work and relating this satellite signal to the water and plants. And we had found out that, yes, we can see basically plants growing that as they grow and develop, they accumulate more water. And then they get to the maximum amount of water that they'd hold, which happens about sometime in about the middle of August here. And then, because their annual plans, they die and they dry out, and eventually we harvest them. We found that we could do we could look at see how these plants grew and accumulated water, but it was a pretty noisy signal. In other words, there was a lot of variability in it. So we started thinking, well, what are some other things that we could do to measure the amount of water in plants and how might we use that information? And we came up with some ideas, and we're currently testing them right now. And what we think we can do is not only look at how the water in crops change over the growing season, how it accumulates and then decreases. We wanted to know if we can actually use these satellites to look at how water or in crops changes from morning to evening. Could we see that? Because if we can see that it turns out the satellite, the NASA satellite that we're using, makes measurements in the morning, and then again in the evening at 6am, at 6pm. So we thought, could we actually see a difference in the water and crops between that two times, and there's lots of reasons why we wouldn't be able to do this. Number one, with the satellite see a very large area. Basically, there's one measurement for all of Story County, right, where Ames is, we can't see individual fields, everything in storey county is kind of getting mishmash together in this one measurement. However, there's a lot of crops in Story County, for example. And so they're influencing this measurement the most. And then there's some other things that we were not sure that we would be able to figure out. But the reason why we are interested in looking at water in the morning versus one The evening is for the following reason. We think that when plants are happy, in other words, plants are they have enough water to do the thing that they're made to do, which is to turn sunlight into the stuff that we harvest the food feed fiber fuel that we harvest from crops, when they're happy. They do photosynthesis, which is this chemical process and leaves that turn sunlight and water into and carbon dioxide into these carbohydrates that we harvest in oxygen. To do that, they have to open little tiny holes in their leaves that we call stigmata. They have to open them up because to do photosynthesis, they need that carbon dioxide to come in to the leaves. Okay. Turns out though, when they open their stomata to pink in the carbon dioxide, water vapor leaks out. So, for plants to do photosynthesis and do what we want them to do, they have an A have to have enough water so they can afford to lose some water when they're bringing in this carbon dioxide. So what we think spend a little to spend a little to make a little bend a little to make a little. So what we think we should see if plants are happy, they have enough water that they can get to in the soil via their roots. We think that in the morning, they should be their juiciest, they should be nice and juicy, because over the night, there wasn't any sun. So they've kept their stemmata closed. And the roots have had time to bring in water to charge them up. But then the sun comes up. And if they're happy, they're going to open their holes open their stemmata so they can start bringing in the carbon dioxide. But then the water vapor is going to start leaking out. And their roots can't quite keep up during the day with the loss of water. They can't bring in enough water from the soil that they're losing through their stomata. And so we expect that in the morning. They're juiciest, but then by the evening, when the satellite passes over again, they should have dried out a little bit if they were happy, okay. Plants that are not happy. They don't have enough water in the soil. we're hypothesizing we're making a guess here what we should see is that their water plant water doesn't change during the day because in the morning when the sun came up, they said whoa, I don't have enough water in the soil to do photosynthesis. today. I'm going to keep my stemmata closed. And so we're expecting that stressed plants plants that are water stressed that don't have enough access to water, they would look the same in terms of their internal water in the morning in the evening. So again, to recap happy plants, we should see a difference. More water in the morning, less water in the evening. Stress plants we should see the same that's our hypothesis. And we've been taught Go ahead.

Paul Yeager: Well, you know the old eyeball test of looking at a field when you're driving by at four o'clock in the afternoon when it's really warm. That leaf really kind of curls under and it always protects the moisture and that's when we always think the crop is stressed but if this is way more than than than eyeballs here on these plants,

Brian Hornbuckle: This is more this is this is microwave eyeballs looking at the plant now In a way that we can put a number to it. And so our hope is that we can look at number one, we want to, we want to see if we can see this difference between morning and evening. And then our hope is that we could put a number on that and say, how stressed was that plant that day? And that could help us understand, what are we going to get? In the fall when we harvest trees, if we had more stress,

Paul Yeager: you might understand, we had, you might understand that that was that real stress in June or that week in July, or that week in August is maybe why we lost 5% of our bushels per acre

Brian Hornbuckle: because the plant couldn't open its tomato during that time, because it didn't have enough water to do that. That's that's what that's what we hope to see. Now we're in the very early stages of looking at this. And we've only done this at three different points in Iowa so far. And we've looked at drought years versus non drought years. And we see a signal that is consistent with what we think we should see. But there's a lot more work here to be done, to really make sure that we're understanding what the data says. But the exciting thing,

Paul Yeager: I guess, Doc, go ahead. Doctor, I'll ask you this. As we get towards the end of our discussion, if I'm a producer of a field, what am I hoping that your data allows me to change or alter my farming practices to better to be a more proficient producer of grain.

Brian Hornbuckle: Right? So here in Iowa, we operate primarily rain fed systems, right? We're not doing any irrigation. So for the vast majority of farmers here in Iowa, we're not making decisions about should I irrigate or not? If I were in a situation like in western Nebraska, where your irrigation was a thing, then this information would help you decide do I need to turn the irrigation on or not? Here in Iowa, potentially what we could use this information for, is to make marketing decisions. We can say, all right, I know there's been this number of water stress days. And I can use that information to say, All right, I'm gonna take this much of a yield hit when I harvest this fall. And that might help me decide whether or not I'm going to sell the grain that I've got stored right now or later, how might prices be like later on when I'm harvesting, I can look at what's happening in other areas in terms of the amount of water stress that's happened over the growing season. So this information will help you make some marketing decisions, not management decisions, because we don't irrigate but some marketing decisions about what to do with your crop and the crop that you've got stored in terms of prices and things like that.

Paul Yeager: This is fascinating. Dr. Hornbuckle, I have to say, the science side of things is not always my strength, but to hear the science and the hypothesis that you're going for. I really think, be curious to see how this turns out. Give me a timetable on. How long does this latest round of experiments expect to last?

Brian Hornbuckle: No. So I have a graduate student I'm working with right now who just finished or is in the process of finishing, and he's the one that's worked with me to do this initial study. But again, there's lots of things to be looking at here. We were just awarded a NASA grant for three years to do this, among some other things. So I'm hoping by the end of this three year period, that we would have, of course, a lot more information on whether or not this is going to work. Are we going to be all the way there yet? Don't know. That's why we call this research because no one's done it before.

Paul Yeager: That's right. Okay, doctor, I appreciate your time. Thank you so very much for the insight and is class dismissed, or is there a quiz now?

Brian Hornbuckle: That's up to you. I can give you a quiz.

Paul Yeager: Yeah, I don't know how well I would do. But that's what that's what this format allows us to do. Dr. Brian Hornbuckle from Iowa State University. Thank you very much.

Brian Hornbuckle: All right. Thank you.

Paul Yeager: My thanks to Brian Hornbuckle from Iowa. State University Iowa native who took an interesting route to get to where he is today and we'll look forward to see how that data and research unfold. If you have other topics you're looking for more insight from us or just things you want to send to me, send me an email MarkettoMarket@IowaPBS.org. Thank you so very much for watching, and have a great week.

Contact: Paul.Yeager@iowapbs.org