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The Land ‘Calls Out’; Runkle Discusses Rice Production in Arkansas

Short Talks From the Hill, a podcast from the University of Arkansas, highlights research and scholarly work across campus. Each segment features a university researcher discussing his or her work.

Matt McGowan: Welcome to Short Talks From the Hill, a podcast of the University of Arkansas. My name is Matt McGowan. Today I’m talking to Benjamin Runkle, assistant professor of biological and agricultural engineering. Welcome Benjamin and thank you for being here.

Benjamin Runkle: Thank you.

Benjamin Runkle

Benjamin Runkle

MM: I’d like to start by sort of zooming out just a little bit. I just mentioned that you are a biological and agricultural engineer, and your case specifically, we’re talking about agricultural engineering. I think most people have a general idea of what an engineer is, but can you talk a little bit about your profession your specific area what do agricultural engineers do?

BR: Right. Well, engineering, generally speaking, is the application of science to become more efficient in our operations as humans, and in agricultural engineering, we’re working with farmers to increase the efficiency of their operations to produce more crops with fewer inputs and to do so with less labor, often in a more marketable way.

MM: This year, back in April, you received a National Science Foundation Career Award. Everyone calls them calls them a Career Award but the formal name is a Faculty Early Career Development Award, and yours was for slightly more than half a million dollars. Could you talk about the significance of the these awards yourself? These are pretty prestigious awards.

BR: They are prestigious and they are exciting to get. They are a mark of an investment by the NSF and to young faculty who seem to have promising ideas for all facets of their academic life. One of several unique things about the grant one is that it’s a combined emphasis on research and teaching. There’s a strong educational component to the award, as well as the research. It’s also a five-year grant instead of a typical three-year grant, so you have to think on a longer time horizon. You can have a second question that depends on the output of first question. That might not come for three more years, and so that also allows me to plan out the next five years of my career, when I will be able to hire PhD students when I’ll be able to work on different questions on a longer timeframe that I’m kind of encouraged to do on other grants. So that’s quite nice. The grant supports an educational component to the work, and I’ll be working with three different “East” programs in the state of Arkansas, that’s environmental and spatial technology, it’s a high school or middle school kind of club or project-based learning class, and so I’ll be working with three different classrooms to help them help us.

MM: Are these schools in the delta?

BR: One is near Jonesboro, one is in Stuttgart, and one is here in Springdale. That will take some of the results that we’re doing and help to model or game them or use drones to help us collect data, stuff like that, that we’ll be doing to help expose students of different levels and different backgrounds to possible careers or study paths and food and agricultural sciences.

MM: It’s interesting to me that it’s a National Science Foundation grant. I don’t know if the Department of Agriculture has Career Awards, but I think it’s interesting that this was an NSF award.

BR: Right. Yeah, that’s right. Many of the agencies do have something similar. So Department of Energy, Department of Agriculture both have early career Awards and options. They’re all written a little bit differently. The NSF one is, I think, unique in having this teaching emphasis, as well, and there is a big engineering directorate within NSF, so this was seen as a kind of mix of science and engineering with some applications outside of agriculture. I think it was relevant for the funders at the NSF, and not only from the USDA.

MM: Thank you. So your Career Award is helping you… you alluded to this earlier… it’s helping you expand your research on developing sustainable methods for rice farming. And we’re talking about down in the Delta, the southeast part of Arkansas. I want you to tell us about that, but let’s first talk about rice. Arkansas is the top American producer of rice. Why is that the case?

BR: Right, yeah so Arkansas actually does produce about half the rice is grown in the United States. That’s roughly equivalent to the amount of rice that Americans eat each year, is produced in Arkansas. The U.S. exports about half of its rice, so we’re really a dominant player and in global rice production and specifically in the U.S. Arkansas… the whole Delta region of Arkansas is very flat, has rich fertile soils that are well conducive to rice production. The Mississippi River Delta is actually an alluvial plain that’s on the banks of the Mississippi River, and by far the greatest portion of that Delta region is in Arkansas. So it’s very similar agriculture, including rice, produced and practiced on the Mississippi side and the Missouri side and then the northern Louisiana side of the Delta, but Arkansas has the dominance of that area. Those rich soils have been deposited by the river over millennia, and the clays there are really good at holding in water, which relates to the water use in rice production, that those fields drain very slowly, they’re very swampy. The rice has an ability to withstand those conditions that other crops don’t have. So a lot of the land essentially calls out to be to be used as rice production fields.

MM: When I think about rice farming, and you just kind of indicated this, the first thought that comes to mind is water and rice paddies, thinking that maybe, I don’t know where I picked this up, perhaps images or maybe movies, Hollywood of Vietnam or something, Southeast Asia, where there’s a lot of rice farming, can you tell us a little bit more about these traditional rice farming methods?

BR: Yeah sure, so why do we flood rice, but we don’t flood other plants. Rice is a semi-aquatic plant. It has the ability to withstand flooded conditions, so actually the rice or the flood water prevents oxygen from going into the root zone, which chokes out most non aquatic plants, which are most of the weed species, non-aquatic species, so it’s natural means of weed suppression to flood the fields. Rice has an adaptation that allows it to grow under those conditions, because it is essentially structured… it’s a grass, but it has a tube-like structure on the inside that’s something like a drinking straw that allows oxygen to come into the roots from the plant itself rather than from the open soil spaces that at traditional dryland crop would be exposed to.

MM: I see. Okay, so all this water is kind of a problem. And so we we’ve known this, you guys, engineers, agricultural engineers and ag… rice farmers have known this for a while. You’re working with several of these farmers in the Arkansas Delta to address this issue, and the Career Award is helping you do that. Tell us what you’re doing down there, what are the alternative strategies for farming rice, and what are the advantages or benefits of these alternative strategies.

BR: Right, sorry, so let me let me just start by saying that using a lot of water for rice is okay in places where there is plentiful water. Unfortunately, much of the water that’s used in Arkansas is from the groundwater, which is being used at a faster rate than it’s being naturally replenished so the farmers are having to lower their wells from year to year, decade to get into decade, and we’re not yet bending the curve on how much water is being withdrawn for the groundwater reservoirs.

MM: I see.

BR: So some farmers are doing things like putting in surface water reservoirs, tapping other water supplies, even switching away from rice production into other crops that might use less water. But a lot of the soil, as I said, is clay and is naturally conducive to growing rice. Rice is a big part of the culture and economy of the state. And so some of the alternate methods of growing rice involve using less water by parsing it out more carefully through their growing season of rice, and one of those in particular is called alternate wetting and drying. So that introduces drying periods, intermixed through the flood periods that rice is exposed to at certain times. The summer rice does not need to be flooded, and where the farmers have taken advantage of the flooding or herbicides to get rid of the weeds, then they’re able to dry out the soils and that allows them to capture more rainfall, rainfall which would have in the flooded case just run off the end of the field. They’re able to use that and then they’re also able to just simply apply less water from the groundwater.

MM: And is there an example of that? I think in what we talked about previously, when I had written about your work, was a sort of an inlet system using piping.

BR: Right, yeah, yeah, that’s one of the strategies that they use. It’s called multiple inlet rice irrigation, and that’s using this plastic piping that allows water to get to the field very quickly. That’s used in farms that have some slope. There are also farmers who converted their farms to having zero grade or zero slope, so it’s completely as flat as a table, and in those cases, they water from all four sides towards the center of the field, so that the water spreads across those fields very efficiently and then is able to be held in place, maybe something like a small bath. Our work will help demonstrate when it is okay and not okay to implement these alternate wetting and drying strategies or use of the plastic piping to get water across the field more efficiently, and how much water will be saved, and then also something about the greenhouse gas emissions. And there I should explain that the flooded conditions of rice production produce swampy soils, in those swampy soil environments you have methane. That’s a powerful greenhouse gas. It’s about five times more potent as a greenhouse gas than carbon dioxide, and that’s produced under these swampy conditions without the presence of oxygen, and so interrupting those swampy conditions with his periodic dry-down events reduces the production of methane from rice fields and globally. Rice fields are responsible for about 0 to 5 percent of anthropogenic, or human-caused, methane emissions to the atmosphere, so it’s a significant part of our greenhouse gas story and responsibility.

MM: Well Ben, thank you very much for your work and your service to the state, and thank you for being with us here today.

BR: Yes.

MM: Music for Short Talks From the Hill was written and performed by Ben Harris, guitar instructor at the University of Arkansas. For more information and additional podcasts, go to or, the home of research news at the University of Arkansas.

About The Author

Matt McGowan writes about research in the College of Engineering, Sam M. Walton College of Business, School of Law and other areas. He is the editor of Short Talks From the Hill, a podcast of the University of Arkansas. Reach him at 479-575-4246 or

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