The Yuma Center of Excellence for Desert Agriculture (YCEDA) is a research center at the University of Arizona (UA) that links farmers, researchers, and students. Its mission is to identify the needs of Arizona farmers, find researchers to work on meeting those needs, fund them with money donated by the agricultural industry and other sources, and then diffuse the results of their research among the farmers.

In this interview, YCEDA Executive Director Paul Brierley speaks with Irrigation Leader Managing Editor Joshua Dill about the exciting research his center is coordinating.

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Joshua Dill: Please tell us about your background and how you came to be in your current position.

Paul Brierley: I grew up on a small farm in California, went to college, and became a computer scientist. I spent about 5 years in telecommunications research. Because I missed the rural lifestyle, I went back to production agriculture in Arizona in 1993. After about a dozen years, I ended up going to the Arizona Farm Bureau and working on grassroots issues advocacy. I got to know the state’s agriculture well. That led to my being selected as the first executive director of this center when it was started.

Joshua Dill: Please tell us about YCEDA and its history.

Paul Brierley: There was a new dean of the UA College of Agriculture who toured the state of Arizona to learn about its agriculture and saw that Yuma was a real gem, with world- class agriculture, huge productivity, and a good relationship with the university. At the same time, the university and the cooperative extension were undergoing all sorts of budget cuts. His question was how the university could support this industry at the needed level. He worked with the industry and came up with the idea of a public-private partnership. The industry agreed to fund the center if it was allowed some influence over research topics and if the center’s results were useful. That is how it worked out. The industry funds the center and sits on the advisory council. If the center provides good results that contribute to resolving the industry’s urgent issues, the industry will continue to fund it.

In the last 4 years, we’ve gone from just me to five of us now. Our most recent hire, who came on last fall, is Stephanie Slinski, our associate director for applied research and development. She’s a PhD plant pathologist who understands the issues and the research networks. She’s really taken us to the next level of capability.

Joshua Dill: What is the relation between YCEDA and the university today?

Paul Brierley: YCEDA is an organization within the university. I am a university employee and work directly for the vice president of agriculture, life and veterinary sciences, and cooperative extension.

The way the industry partners with us is that individual investors commit to fund our center via tax-deductible donations to the University of Arizona Foundation. Eight donors and UA’s vice president for ag, life and veterinary sciences, and cooperative extension sit on YCEDA’s advisory council, which gives me some guidance on the issues it would like worked on.

YCEDA does not do research itself. It tries to be a bridge that makes sure that research occurs on the issues that are important to our stakeholders. We get advice from our stakeholders, pull together researchers, try to get funding, and keep the research focused on usable results for the production industry. Then we disseminate those results back to the stakeholders.

Joshua Dill: Would it be accurate to say that YCEDA is a project manager for agricultural research?

Paul Brierley: Yes. It turns out that one of the main challenges is finding the people to actually do the research and making them aware of and interested in the problems that are affecting production agriculture. Despite our affiliation with the university, we are not constrained to collaborating with researchers employed by the university. We work with experts from other universities, like UC Davis, or from companies like Syngenta or even Raytheon. The key thing is finding the right partner, getting them focused on these problems, and providing the resources to get that research done.

Our advisory council helps us stay in close touch with industry needs. They bring ideas to us and tell us about their problems. Researchers come to us with ideas and proposals and we vet those. We can run those ideas by our advisory council to figure out where to focus our efforts. The number 1 issue that they’d like addressed is maximizing productivity.

Joshua Dill: How do you diffuse your research results?

Paul Brierley: We hold field days and research symposiums, and have a website, publications, and various other means to get information out. One advantage we have is that pretty much anything we work on is something that the industry needs and wants to incorporate into its operations. Our results are not just going to be a report on a shelf somewhere; they are going to be put to use and have an effect.

Joshua Dill: What are the main projects YCEDA works on?

Paul Brierley: One of the first things I was asked to work on at YCEDA was productivity. The biggest obstacle to productivity was plant disease. As the climate changes, different  diseases come in, including soilborne diseases and mildews. One example is fusarium of lettuce, a soilborne disease that is currently spreading. There is really not a solution for it at the moment. Most diseases can be treated with a spray or a cultural practice, but with fusarium, you can’t plant lettuce in affected fields. We’ve had a number of projects in that area, including disease identification, remote sensing identification using spectral imaging, and DNA analysis. We’ve tried to identify thresholds from soil testing to help decide where to plant. We’d like to be able to predict whether a crop will get fusarium in a given field at a given time. We are in the infancy of identifying and quantifying this disease. Those tools will help growers predict whether their crops will get the disease, but they will also be able to analyze the efficacy of different ways of managing the disease. That could be resistant varieties. We’ve had 4 years in a row of field trials in which we look at new and current varieties of lettuce to see if they’re resistant to the disease. We try different crop protection products and cultural methods and try to figure out ways that this disease can be managed.

Joshua Dill: Tell us about your soil salinity study. What is the problem that you are trying to solve?

Paul Brierley: As I was coming on board 4 years ago, the irrigation districts here were working with a group of stakeholders including the Bureau of Reclamation, the Arizona Department of Water Resources, and UA on a study of water efficiency. All irrigation in the Yuma area uses water from the Colorado River, which has a lot of pressures on it from drought and development and the push and pull between states and urban and rural users. The study looked at the source of the water, how it was distributed to the farms, how it was used, and how productive it was. They looked at what was produced using the water and at the improvements in efficiency that have occurred over the past 20–30 years,
and concluded that we were using 18 percent less water than we used 30 years ago and in some cases producing double the crop. The study tried to quantify all that. As in any study, however, there were gaps and further questions. One question concerned the necessity of pre-irrigation. There is a practice in this area of pre-irrigating before the vegetable season in order to push salts down below the root zone.

We undertook a study at the behest of the Yuma Agriculture Water Coalition, a coalition of irrigation districts, to look at crop water needs and soil salinity levels. The existing figures for evapotranspiration coefficients and things like that date back to the 1950s. Cropping patterns and yields are a lot different now. Crops such as lettuce are producing twice as much yield as they used to. We wanted to look at things like evapotranspiration and water needs from a holistic perspective, including the whole rotation cropping cycle throughout the year. We partnered with a UA researcher and a researcher from the U.S. Department of Agriculture’s Arid Land Agricultural Research Center. One task was to measure every bit of water applied to the field. We have expensive, high-tech measurement devices that measure all the incoming water, the evapotranspiration, the evaporation, and the leaching. Some of the water was being used by the crop, some was evaporating off, some was going down through the soil. We also observed what was happening to the salinity in the soil at different depths.

We built a huge database as we added more partners and more equipment, and we ended up with the ability to measure eight different crops at a time. We could do iterations of the same crop or different crops. We measured on different scales, as well: We had equipment on the ground measuring at the field level and we had equipment that was more at the regional level, measuring areas a mile or two across. We are actually taking measurements with satellites and ground-truthing that with drones and similar sensors. The goal is to eventually be able to get these measurements from satellites without having to disrupt field work with measurement equipment.

A drone with a UA engineering student–designed pollen dispenser pollinates a Medjool date palm tree in Yuma, Arizona.

We are getting precise updated evapotranspiration coefficients for all the major crops in the Yuma area so that we can figure out exactly how much water those crops need. We hope to give the growers the information they need to more precisely select their crops, irrigate their crops, and engage in practices like pre-irrigation more precisely.

Joshua Dill: Does this study aim more at increasing production or at saving water?

Paul Brierley: It’s a little bit of both, because if you’re not leaching enough salt, then you’re going to be hurting your production. If you’re putting on more water than is necessary to leach the salts, then you can save water. It’s just a matter at this point of quantifying crop needs and soil salinity. It turns out that the farmers were doing a pretty good job. The words “water efficiency” have taken on a new meaning in my mind. It always seemed like a categorically good thing, but it turns out that if you get past 80–90 percent efficient you’re not adding enough water to properly leach the salts, thus increasing soil salinity.

Joshua Dill: Does YCEDA work with students at the university?

Paul Brierley: We’re doing that more and more. Our drone pollination project is a good example. The industry came to the university cooperative extension with the idea quite a few years ago. UA has a regional campus here in Yuma, which has an engineering program. Some senior engineering students took it on as a senior design project 3 years ago. They proved that pollinating from a drone actually gets the pollen where it is needed. They built a dispenser and a drone and pollinated date trees with it, and actually won the overall design contest for the whole university. This year, to carry that forward, we are working with the McGuire Center for Entrepreneurialism at UA. YCEDA sponsored a two-semester class in which three engineering teams are working on building a commercializable pollinator drone prototype. An MBA class is working on a path to market. The hope is that the students can create a commercializable prototype with a path to market and that they can actually create a startup and carry this idea to commercialization by licensing the technology from the university. If that succeeds, the students will have created a commercial entity, the industry will have a solution, and the university will have a small revenue stream from the licensing of the technology.That’s one example I’m really excited about right now.

Joshua Dill: What is your vision for the future?

Paul Brierley: First of all, to do more of what we’re doing. I want to broaden our collaboration network, making sure we’re working with top-notch researchers on the urgent issues of the day. I want YCEDA to become more of a grant-giving organization. Right now, we typically go out with our research partners and try to bring in grant funds to support their research. I would love it if we had enough of a war chest that we could be the grant-giving agency. Then we could put people to work immediately on an issue instead of having to go through the whole laborious process of applying for a grant and waiting for approval and all that. I will always stay true to our industry focus. That is what differentiates us: We produce results that are meaningful and useful to the production ag industry. It’s a new model for university engagement with industry. So far, the track record has been good and I’m excited for the future.

Paul Brierley is the executive director for the Yuma Center of Excellence for Desert Agriculture. He can be contacted at