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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. For many soybean growers, an important step is the inoculation process, be it wet, dry, or after planting. How important is inoculating soybeans? Victor Gomes, NDSU Extension cropping systems specialist, has been doing research. Victor, tell us about the soybean inoculate research you've been doing.
Victor Gomes:In 2025, we conducted the first year of research on this North Dakota Soybean Council sponsored project titled determining soybean inoculation strategies for Western North Dakota, in which we studied two different soybean inoculant strains. So we had a Bradyrhizobium japonicum, and a Bradyrhizobium alcani. Both of them are commercially available inoculants that you can buy from your dealer. And with each of those inoculants, we look at three different rates of one times, two times, and three times what is recommended on the label, as well as a treatment combining both inoculants, and two treatments that would combine each inoculant with a starter nitrogen fertilizer of 20 pounds of N per acre. And we also had a treatment with just nitrogen at 20 pounds per acre in an untreated check. We conducted that trial across four different RECs in Western North Dakota. So we had that trial in Dickinson, Williston, Hettinger, and Minot. After establishing the trials, we analyzed not only the crop performance in terms of yield, we also analyzed nodulating rhizobia population in the soil.
Bruce Sundeen:What has your research discovered so far?
Victor Gomes:What we found with this first year of research is that inoculation, yes, is important. It does outcompete the untreated check across all locations. However, the best treatments do differ based on where you are. So pretty much in Dickinson and Williston, any treatment containing an inoculant was better than a control. In Hettinger, the gains were very little, and for them, three times the recommended rate of the liquid inoculant containing Bradyrhizobium japonicum was the best result. And it might not, with might not being the only site where we could detect a pre existing rhizobia population in the soil, we did not see an increased benefit of that inoculation. So probably they already had a very well established Rhizobia population in the soil, so adding more did not make a difference. But overall, what we observed with this first year of trial is that the results were a little scattered, a little inconsistent across locations, and that's somewhat what we already expected. If we look at where these inoculants come from, we will see that they were isolated in the 50s in the areas of The United States where the soybean as a crop was established first. So areas of Florida, Illinois, and they were isolated in Maryland by the USDA there. So we don't really have a native rhizobia from North Dakota that could better establish available.
Bruce Sundeen:Why is native rhizobia important?
Victor Gomes:Think of it, Bruce. If I were to take you and strip you of everything that makes your life what it is now, if I take away your car, your phone, your salary, your job, your family, and friends, and throw you in the, Mojave Desert and hope that you make do and you thrive there. Chances are it's and I'm not doubting your survivalist skills, but chances are you're not gonna thrive. So it's the same situation with these inoculants. We're taking this foreign organism and putting it in our soils and hoping that they're gonna work. So I know that Doctor. Barney Geddes is now leading a search for a native inoculant that can be found here and that we can isolate and produce in commercial scale to make available for our growers. But until we get there, even though inoculation is important, I'm not trying to tell farmers not to do it, the response of that inoculation is gonna be finicky. It's not gonna be very consistent from one ear to the other.
Bruce Sundeen:Victor, do you have any recommendations?
Victor Gomes:My message here is keep inoculating your soybeans. Typically, what we saw with our research is that using the standard rate works well. It gives you a boost there, but hopefully, we're gonna have something local, more adapted organism to recommend in the coming years. So we're hopeful for that, and I'm sure that's gonna help boost your soybean acres.
Bruce Sundeen:Thanks, Victor. Our guest has been Victor Gomes, NDSU Extension cropping systems specialist. 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.