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The NDSU Extension weekly podcast In the Pod: Soybean Updates delivers timely insights and expert advice on soybean production.
You're listening to In The Pod, Soybean Updates, a weekly trek into the latest soybean information from NDSU Extension. All farmers want the best possible yield from their crops. With soybean, finding the optimum phosphorus level can be challenging. Lindsay Malone, NDSU assistant professor in conservation agronomy, is conducting a phosphorus study. Lindsay, tell us about your research.
Lindsay Malone:Sure. Yeah. So I've been here at NDSU for about three and a half years, and my group really focuses on conservation agronomy. So while a lot of what we do is really heavy on things like cover crops, I also think that anything where we're talking about sustainably increasing yield, kind of that old hallmark of agronomy, is really important. So my graduate research really focused on soybean systems, in particular soil health and soybean systems in Wisconsin. A lot of that was funded by Wisconsin soybean checkoff dollars, and a lot of that has carried over here into North Dakota as well through a lot of support from the North Dakota Soybean Council and North Dakota checkoff dollars.
Bruce Sundeen:So some of that history. Is that how you got into phosphorus in soybean work?
Lindsay Malone:Yeah. Absolutely. So this came from a question from the Soybean Council and, collaboration with Dave Fransen when I first started here nearly four years ago. So soybean is a relatively new crop to North Dakota. In the last twenty years, it's gone from about a million to 6,000,000 acres of soybean across the state, and a lot of that is movement west. So a lot of our fertility guidelines really focus on the Red River Valley. And with this study, we looked at 16 site years across the state. So this included collaboration with folks in Minot, Dickinson, and Carrington looking at phosphorus fertilizer rates across the whole state to hopefully improve recommendations.
Bruce Sundeen:So what did you find?
Lindsay Malone:Most of our sites, we did not see a response probably because something else was limiting. Maybe it was water. Maybe it was other nutrients. We had IDC at a couple of sites. We did see a boost in yield from just a small amount of phosphorus at three of the 16 sites. But then when we looked at the sites altogether, our research really does support maintaining a moderate soil test p level, say above eight parts per million Olsen to really maximize that yield potential. So you're sort of ensuring that phosphorus isn't going to be limiting if we're maintaining that level above eight parts per million.
Bruce Sundeen:Did you have an opportunity to study anything else?
Lindsay Malone:Yeah. Absolutely. So one of my favorite things to do with field studies is to ask extra questions. Oftentimes, these are really, like, conservation related questions and leverage field sites for more research since it's a lot of work, and we also want to use these checkoff dollars to the the full extent to establish these sites. So we use this study to also look at our buscular mycorrhizae fungi. AMF for short is a plant symbiont that helps with phosphorus and water uptake. So we just looked at this at five of the sites and some of the positive things. So we didn't see any negative impacts on AMF from these fertilizer additions, which is a good thing. Sometimes we worry that if we have too much phosphorus in the system, it's going to help basically tell the plant, oh, you don't need that symbiotic relationship. You're good. But we didn't actually see that impact. Granted, this was just a one year study. So we fertilized in the spring, and then we looked at these AMF populations and colonization in August. But the thing that I was the most excited about is that we did see colonization at all five sites. So there are native populations of this AMF plant Symbiont at all of these sites. The highest colonization rates were actually in Dickinson, I think because it was our only true no till site. So reducing tillage is gonna help preserve those fungal mycelial networks, which is gonna help with a lot of other soil health impacts as well.
Bruce Sundeen:Lindsay, do you have any final comments?
Lindsay Malone:Sure. We are looking for farmers for an on farm research study this summer in 2026. This is some research that's funded by the North Central Soybean Research Program, NCSRP, testing some really cool management tools and some scouting software. So I'd love folks to reach out if they're interested in partnering with us on that.
Bruce Sundeen:What's the best way to get more information about the study?
Lindsay Malone:Reaching out to me over email is probably the best way to get more info. My email is lindsay.malone@ndsu.edu.
Bruce Sundeen:Thanks, Lindsay. Our guest has been Lindsay Malone, NDSU assistant professor in conservation agronomy. You're listening to In the Pod, Soybean Updates, a weekly trek into the latest soybean information from NDSU Extension, supported by the North Dakota Soybean Council.