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Welcome to University of Minnesota Extension's Nutrient Management Podcast. Each month we bring you the latest research in nutrient management for crops and how you can incorporate the latest tips and best management practices to your farm.
Hello, and welcome to the Nutrient Management Podcast from University of Minnesota Extension. I am Jack Wilcox in communications here within Extension. Being mid October, it's time for a Fall manure outlook. So we have new updates to our Manure application rate guidelines. We have some updates on the NUR DB, and we'll discuss some important best practices among other things.
Jack Wilcox:We have three specialists, educators, and researchers to guide us through. Can you each please introduce yourselves?
Nancy Bohl Bormann:Yeah. Thanks, Jack. I'm Nancy Bohl Bormann. I'm a re... Manure and nutrient management researcher in the University of Minnesota Department of Soil, Water, and Climate on the Saint Paul campus.
Chryseis Modderman:Hi. I'm Kristin Smoderman, extension educator with the University of Minnesota. My office is out in Morris, Minnesota, and I focus on manure nutrient management education.
Stephen Gregg:Hi, Jack. My name is Steven Gregg, and I am the on farm research manager and outreach specialist in the Wilson lab. I work in the same lab as as Nancy on the Saint Paul campus.
Jack Wilcox:Talk about the recent update to a manure application rate guidance for corn on corn and corn soybean.
Chryseis Modderman:So big news in the manure world here in Minnesota. The rate... Application rates have been updated in how we calculate those rates. Kind of the high level view is corn on corn rotation is now going to be multiplying your historical yield by 0.9 to get your pounds of nitrogen per acre. And corn soybean rotation, it's the same calculation, but just 0.7 for the multiplication factor.
Chryseis Modderman:And we wanna make sure that we are using historical yield, so we're defining that as five years of data... Of of yield data for for your corn, and you can take out outliers if, you know, if there was a a flood year or, you know, a year that was prevent plant, you can ignore that. So you might have, like, you know, fifteen, ten years of data or whatever in there to get that five years of of average data, or you can take the county average, use the the the county average for your historic yield number. We are being very careful not to use the term yield goal, which was kind of the antiquated way of doing this. Historical yield is kind of what we're going with that.
Chryseis Modderman:And this information is now up on the website on... Under manure application rates... Rate calculations, and there is a crop news article about it now as well. And there's some more notes about specifics for, you know, silage production, those sorts of things that you can find there.
Jack Wilcox:And what was the reason to update the guidelines?
Chryseis Modderman:Basically, we have the data now. We now have the data in manure research data to back up these numbers. You know, way back in the day, it was 1.2 pounds of nitrogen per bushel of corn, and we found that that is not accurate for Minnesota soils. Our soils here in Minnesota have a lot of natural fertility to them. We don't need that level of...
Chryseis Modderman:1.2 is no longer, you know, what we use. So point nine for corn on corn, point seven for corn on soybean is kinda covering the the majority of our more southern parts of the states are the rotations that are just, you know, a corn soybean rotation or continuous corn. If you're applying at a phosphorus based rate, that is still just phosphorus, how much the phosphorus the plant uses. That's the... How we calculate the rate still.
Chryseis Modderman:So phosphorus rate applications is not changing.
Nancy Bohl Bormann:And just to note that for commercial nitrogen fertilizer, still using the MRT and the maximum return to nitrogen is how we calculate that. But since we... It's very hard to pin prices on manure nutrients, that is why we're going kinda slightly different than commercial one.
Chryseis Modderman:And remember, when you when you do that calculation and you find out that, you know, if you have... If your historic yield is is a 180 bushels per acre and on a corn seed... Soybean rotation, you multiply by that point seven, and you get a 126. So that's the maximum rate of nitrogen that we're recommending for corn. But remember, that's plant available nitrogen, not total nitrogen.
Chryseis Modderman:So you still need to do the calculation to figure out how much plant available nitrogen is in that manure.
Nancy Bohl Bormann:It changes depending on how you're applying it and what kind of animal it's from.
Jack Wilcox:A moment, we'll talk about fall best practices. But first, we've been told about a piece of uncommon weather that we're going to all experience here in The United States, a Super El Nino event. Nancy, can you describe what that is?
Nancy Bohl Bormann:No. No. We'll start necessarily climatologists, but, you know, from what we've been seeing, I saw the Minnesota DNR page has information, and maybe we can put this in the links too about it. Sure. Know, it's just looking like the climate trends are pointing to this pattern that will be happening over the winter.
Nancy Bohl Bormann:They said in Minnesota, when we have these El Nino conditions, we tend to have milder winters with less snow on average. So the 27 El Nino winters we've had since 1950 were about 2.4 degrees warmer on the statewide basis, and have about 24% less snow, for example, in the Twin Cities. But they said they're also gonna have intense weather with some heavy snowstorms in there. Just saying that, okay. We're tending to have mild and low snow winters, possibly some bigger events.
Nancy Bohl Bormann:Spring and summer following, El Nino can have active with, you know, some big thunderstorms and stuff... Such like that. So, okay, we're going into this sort of El Nino pattern. What can we think about on a manure application basis?
Stephen Gregg:Especially related to manure option that the fall is typically warmer, and there's a wider window, generally that we've seen in past years with El Ninos. Yeah. Always can have storms and and cold snaps and things. But, typically, we would expect more time for newer application and and a bit later than what we would normally see. And then that also allows, you know, for folks that are incorporating cover crops, there's a bit of a different window for that as well.
Stephen Gregg:So, yeah, really paying attention to the soil temperatures in your area.
Jack Wilcox:That brings us back to best practices. What should we be thinking about as we go into this particular fall?
Nancy Bohl Bormann:You know, instead maybe just watching a calendar date, like watching those soil temperatures, you know, that... If you just search, you know, Minnesota soil temperatures, there's a website out there that you can see across the state where we are trending and kind of looking at the web... Whether is it going to be trending cooler or not. For all nitrogen, we're really, you know, looking to apply that fall nitrogen when it's 50 degrees soil temperature and trending lower. I mean, the reason that is we're applying these nutrients in the ammonium form, which could stay in the soil.
Nancy Bohl Bormann:And if it's cool, those... The microbes aren't aren't working. It's like you're putting them in a refrigerator, slowing them down. But when it... If it's warming up, microbes can convert that ammonium into nitrate, which then is able to travel in water, and we have more more of a risk of losing it.
Nancy Bohl Bormann:So, you know, for applying these nutrients, you know, six months ahead of the crop needing it, that is just, you know, another concern, especially with these fertilizer prices that are so expensive. We wanna make sure we're saving our money and not having to apply more later. Also, I'm not losing them to the environment either. So I guess... Alright.
Nancy Bohl Bormann:Okay. Thinking about that, what are some things we can do in the manure world? I mean, I know we're, you know, worried about our manure storage is getting full. You know, when's the custom applicator coming? How many suitable field days do we have?
Nancy Bohl Bormann:You know, when trying to balance all those things, you know, thinking about what fields might be less risky to apply on. Could we apply a lower rate now and and supplement some of the commercial nitrogen in the spring? Thinking about adding nitrification inhibitors that can help slow that nitrification down. Like Steven meant, you know, mentioned earlier, adding cover crops, you know, if we can capture some of that. But, you know, if we have to get the noradown early, that's a good way to help catch some of that nitrate if we need to.
Nancy Bohl Bormann:And just, you know, trying to be creative if we can and thoughtful. Farming isn't a cookie cutter business anytime, and now the harvest is underway and starting to think about putting down nutrients soon.
Chryseis Modderman:Here in Minnesota, not just in super El Nino years or El Nino years that we are trending warmer in this in the fall. Our... Looking at the thirty year averages, our our falls are trending, you know, a degree to... December is trending two degrees warmer than previous historic thirty year averages. So this is good information for every year, every fall, and the the issues with with fall application are maybe only gonna get worse as things go on, not to be doom and gloom about it.
Chryseis Modderman:But, yeah, the the cover crop recommendation, the the using nitrification inhibitors. If you're applying right now, a nitrification inhibitor would be would be great because most of our soils, at least... I live a little more north in the state. We have not hit that 50 degrees yet. We're...
Chryseis Modderman:We've had some some warm times up here. We'll probably hit that before, like, you, Nancy, and and Steven live south of being quite a bit. We're still, you know, deep in in harvest time, but I know as soon as that corn's off, they're itching to get that that manure out on the ground, and it's like either, you know, pump the brakes a little, wait for that 50 degrees in the in the soil, slow down that nitrification process, or use a nitrification inhibitor or a cover crop.
Nancy Bohl Bormann:Just some of our general manure application timing studies that we've done in Alyssa Wilson's group too and seen around other Midwestern states, you know, the later fall manure applications compared to early fall. Later fall usually usually has better yields. General fall tips that we're thinking about, you know, this time of year always, who's gonna sample the manure? Are you doing it before pumping or during pumping? Do you...
Nancy Bohl Bormann:Are you procuring some sample bottles from a lab? Who's gonna send them in? When are you gonna do that? So just thinking about getting some mineral samples because, again, fertilizer nutrients are expensive, and we wanna try to tailor the nutrient management plan to your farm the best we can. And then, you know, corresponding updating your mineral application rates accordingly.
Nancy Bohl Bormann:Another just general thing that's good to review is our emergency response plans, phone numbers, and everything current, and people that work on your farm current. We got the address listed, all that sort of thing are always good to take a few minutes to review.
Chryseis Modderman:Yeah. That emergency response plan. These are all good things to do if you're trying to... If you're white knuckling, waiting for your time to get out in the field to spread manure, if you have the luxury to be able to wait to be, you know, doing your calculations, your sampling, your soil sampling. Fall soil sampling is is something some people do.
Chryseis Modderman:And reviewing that emergency response plan, having it in a place where everyone can access it, making sure the numbers are up to date. And then the, you know, in season application safety is, you know, very important. When we're agitating pits, the hydrogen sulfide gas can be a big problem. Fairly low concentrations of that can cause major health issues. And it's not just in the confinement barns.
Chryseis Modderman:You hear a lot about the hydrogen sulfide in the in the below a confinement hog operation or something like that. And, you know, that's a confined space if you're entering that. That's very dangerous. But there's also off gases from open pits when they're being agitated as well. So, you know, some people think, oh, it's out in the open air.
Chryseis Modderman:It's gonna be fine. But sometimes those gases can can still be significant there, so making sure that, you know, there's no kids hanging around the the pit or or people that don't need to be there, that sort of thing. And then I'm also gonna plug calibrating your spreader. Not enough people calibrate their manure spreaders. It's like you do all this work to calculate your application rate, and then you don't know what you're actually applying out there.
Chryseis Modderman:So take take some time to do that as well.
Nancy Bohl Bormann:Just remember when you're actually pumping, making sure the appropriate record keeping things like what dates did we put this in, what fields, all the usual record keeping things. You know, do it so you'll remember what you did later on, not next year trying to to look back and guess.
Jack Wilcox:Let's remind our listeners about the online database, ManureDB. And, Nancy, you were able to add about 30,000 new samples to that tool. That's quite an update.
Nancy Bohl Bormann:Yeah. That's right. We just did a large update on September 1 to ManureDB with... If you're not familiar, it's the Mineral Nutrient database that's based out of you you know, down here. And we've been working the last few years trying to aggregate manure data from across The US into it, and we try to go back to our labs and collaborators each year to try to add more samples to the database.
Nancy Bohl Bormann:So we did. I... And always looking for new collaborators too. So this is a combination of new collaborators and twenty twenty five data. We added another 30,000 samples.
Nancy Bohl Bormann:So we're over 580,000 samples now today, so that's pretty exciting. And, really, over quarter million samples are from the Midwest. So we have a really great representation of Midwest manure, I would say. On our... We have a resources tab.
Nancy Bohl Bormann:We've had a few papers published with ManureDB data the last few months. So if you're really interested in learning out about manure data, you can check out the resources tab. And always trying to make it the website easier to use, you know, some easy graphics on them and tables on the first page and then on the dashboard. And on the second tab, we have a data explorer where you can download the data and look at more specific things if you're interested.
Jack Wilcox:Are micronutrients included in this data?
Nancy Bohl Bormann:One neat thing about manure DB is that... I mean, yes, we know that nitrogen, phosphorus, and potassium are the most commonly analyzed nutrients in manure. I think we have, like, 98, 99% of the samples have that analyzed. However, quite a few of the samples also analyze for micronutrients. Quite a few of them, 50, 60% of the samples have a lot of the micronutrients, analyzed.
Nancy Bohl Bormann:So this can kinda also give a kind of a good idea of what some manures might have, if you have not looked at that previously. So I know one thing that's gotten more interest lately in Minnesota is sulfur levels and what kind of sulfur recommendations is... Are there. Just looking at the the website, and hopefully, you can put this in the show notes too, is the sulfur for Minnesota soils. I mean, for corn, just kind of a general update is they're recommending 25 pounds of sulfur for corn on sandy soils and about 10 to 15 pounds of sulfur for medium and fine textured soils for corn.
Nancy Bohl Bormann:And, I mean, there's some other nuance to that. Check the website, but that's kind of just a a quick overview. Okay. So now knowing that, like, what what can we expect in some of these different manures? You know, I'm kinda hear that there's...
Nancy Bohl Bormann:They have all kinds of nutrients in and out, but what what could we may possibly expect? So I would just kinda looking through the data just now that we have this, you know, new addition. I looked back from 2021 to 2025, so five years of real recent data for the Midwest, and it looked at a few of the more common manure types. And just to give you all the audience, I guess, a little taste of what we can do here, looked at the liquid dairy manure, and the median, which is the middle value of all those for sulfur, was about three pounds of sulfur per thousand gallons, and that's out of 28,000 samples. Liquid swine manure is about five pounds of sulfur per thousand out of 15,000 samples.
Nancy Bohl Bormann:Just to show, yes, that's the middle number, but the middle 50% of samples are between two and a half and seven and a half pounds of sulfur per thousand. So that that just shows you how wide, you know, these samples can be and showing... You know, sampling your own manure on your own farm will always give you, you know, the best tailored nutrient management plane. Our liquid beef manure median was about seven and a half pounds of sulfur per thousand gallons. When we switch over to solid manures, the solid dairy median was around two pounds of sulfur per ton.
Nancy Bohl Bormann:Solid beef was around three pounds per ton. Solid swine was around five pounds of sulfur per ton, and solid poultry was around eight pounds of sulfur per ton. So, I mean, that kinda gives you just a real general, overview, something that we can look at fairly easily on our our data dashboard, ManureDB, but also, you know, hey. There... This manure is a pretty good sulfur source for a lot of the application rates you're putting on should fulfill the sulfur needs.
Nancy Bohl Bormann:Again, depending on where you are, your soils, and all that sort of thing, Take a look at.
Jack Wilcox:There will be a link to manure DB in our show notes, so be sure to look there for more information. Steven, let's pivot to on farm research. What's currently happening and what might be coming up?
Stephen Gregg:We have three collaborators that we're working with for the 2026 season, and the sampling is almost done at these sites in general, you know, driving all around Southern Minnesota. The corn harvest is a little bit behind, you know, what we would see in a typical year. But our... Two of the three of our collaborators have corn already harvested. We are working with folks in Southern Minnesota, but we have research on high cover crops with the manure.
Stephen Gregg:So having a cover crop versus no cover treatment. We have a couple of collaborators that we're working with, manure sensor technology, so testing that out against flat rates to see how well those do. And then, we have a... As of this fall, we just started with a... Another collaborator in Surviv who is using a nitrification inhibitor.
Stephen Gregg:So working, you know, the treatment of nitrification inhibitor versus no inhibitor for the manure applications. And we're... For that one, it's, looking at, Corteva, Instinct next gen is the the product for that. So... And then the the manure sensor that we've been work...
Stephen Gregg:John Deere, manure sensor. And we have some, this is the second year of on farm research that the Wilson Lab has been doing. So there's not a lot of... And I I joined the lab in July. So, kind of running around with extension events and doing some of the sampling, but I haven't looked too much at the data.
Stephen Gregg:But I know for... We have some data back from the manure sensors that, you know, they've been doing a good job at predicting nitrogen amount in in these manures. They do a decent job with organic matter and then need some work for phosphate potassium. But we're gonna be continuing with possibly all of these collaborators for 2027. Everybody has expressed interest in that.
Stephen Gregg:It's a matter of, you know, finding fields that have the proper orientation for them to be able to apply the treatments and, yeah, set everything up in a way that's gonna work well for them. But it's a nice sign that the... These folks want to continue to do on farm research, and I'll be excited to look at a lot of that data, start having a better picture of what what is actually happening in the fields. So we're doing typically, plant sampling at maturity for corn. We're also sampling the cover crops when when that's part of the experiment.
Stephen Gregg:So we're looking at nitrogen content in these crops and then also looking at nitrogen in the soil as a... As another basic sample that we're taking. So looking, what do the nitrogen levels look like for any of these treatments applied, and then, you know, what does that look like after the harvest of a cover crop or of the main crop of corn?
Jack Wilcox:And for those folks who might not be familiar, describe what on farm research is.
Stephen Gregg:Yeah. We are... You know, we have some funding available through the state of Minnesota, and we're able to provide some money to farmers to collaborate on some of the research questions that we, you know, doing manure research, we... We're, very aligned with, you know, what farmers are interested in looking at, and a lot of these are around, you know, crop production, of course, but also water quality. So, there's some basic issues like that that we're trying to, yeah, just kind of really, you know, do some tweaking with the, nutrient management for manure applications.
Stephen Gregg:So we... In... At the lab, we have, you know, the traditional research plot, like small plots at the research centers, but we are very interested in having these experiments on actual farms. So, you know, these are applied... The the treatments are applied and harvested and everything by the farmers themselves, so they're using real world equipment versus, you know, at some of the research centers, things are harvested by hand or they're harvested by different equipment than they would be using on farm.
Stephen Gregg:So this is, yeah, very applicable to to what the farmers will see in the field because we're directly taking measurements there. And, you know, this data that we're doing will, you know, be incorporated in a lot of extension education, and there will be articles published in journals. And this is also some of the work that gets, you know, put into some of the manure recommendations and things like that that that folks will see later. So, yeah, excited to be doing this and continuing it. And, yeah, the the idea is to expand our on farm work.
Stephen Gregg:We can work with more collaborators. Very happy to work with farmers to develop, you know, studies that that fit with their farms and with the... You know, we have some flexibility in terms of what we can can pursue with things, or it's not extremely strict rules on the the research questions we can have. So there's a lot of possibilities to explore different topics that have... Are of interest.
Jack Wilcox:How can listeners contact you if they wanna learn more?
Stephen Gregg:Yeah. You can send an email to manure@umn.edu, and that's something that we check regularly and would be happy to talk more with folks there. And then you can also look up the Wilson Lab, extension page, and we have some of our past research and photos and more information about the lab if you're interested to see some of the work we've been doing and see some, there's some good visual storytelling there. So
Jack Wilcox:One clear takeaway from this episode is to check the show notes. We have all kinds of information down there.
Stephen Gregg:If folks are interested in, potential on farm collaboration like this, that, even if, you know, they're really going forward with a plan for 2027, we're happy to talk about something for, 2028 or, you know, just get in touch with us. It doesn't have to be something that we do immediately this fall. There's a lot of and always just happy to connect with folks.
Jack Wilcox:If you'd like to reach out and contact Nancy, Kristin, Steven, just send an email to manure@umn.edu. Kristin, what upcoming events should we have on our radar?
Chryseis Modderman:Yeah. The commercial animal waste technician recertification online course is active right now. If you have... On your little license card, if you are a CAWT, if it says you need to recertify by, you know, 12/31/2026, this is kind of your last shot from us to do it, this online course. We...
Chryseis Modderman:And it has to be done by the end of October. October 31 is the deadline because then that's the MDA's deadline too. They need to collate all their... The the people to get recertified and send out those notifications and that sort of thing. So, you know, get that in as soon as possible even if you have to do it in your Halloween costume on October 31.
Chryseis Modderman:And if your card says recertify by 2027, we'll see you next year. We'll have a bunch of workshops, you know, January through March. We'll probably be at Farm Fest again doing recertifications, and then the online course will be... There will be one next year as well. And Steven is heading up the checking into that, making sure people are completing all the steps correctly and that sort of thing.
Stephen Gregg:Yeah. I've been answering questions and helping people navigate through there. And, also wanted to add that that online recertification course, it takes about three hours.
Jack Wilcox:And you're teaching a class on manure management too. Is that right for horses?
Chryseis Modderman:Yes. Just a shameless plug for a course that I'll be teaching online starting in January, January 4. It is called the manure management for small farms and horse owners course. It's kind of a basic introduction to manure management. It's part of a larger suite of courses that come from the equine folks.
Chryseis Modderman:There's like a pasture management. There's mortality course. I think there's, like, eight courses this year. But registration will open by November 1 and will run through the day before the course starts. So it'll run through January 3.
Chryseis Modderman:So keep an eye out for that to be announced when registration is open. It should be on the the crop news blog. I'll write an article for that when that... When registration is open, so put that on your radar.
Jack Wilcox:What are some questions you've been hearing from farmers this season?
Chryseis Modderman:I get a lot of questions about that manure sense technology type thing that are... That's on the spreader. So I'm super glad that Steven and and crew in the in the Wilson lab is is working on that so I can give them a science based answer instead of kind of like a well. I know what the promotional material says, but I also know that comes from the company. So it's good to have some data behind that.
Chryseis Modderman:Yeah. Basically, how well does it work and for what does it work well for. And hearing that it works pretty well for nitrogen but not quite so well for phosphorus is not surprising. So so it's it's good to have that validated and and, have a little bit of science going on behind that.
Stephen Gregg:Yeah. And I I wanted to add for that. The newer sensor, you know, we had a couple of sites. And one site, the nitrogen and organic matter worked great, and then, it worked less well for the second site. And that was two different kinds of manures, but there was also a big difference in temperature by about 10 or 15 degrees.
Stephen Gregg:And, our collaborator with that one research site was thinking that that might from, you know, the temperature differences that's giving those different readings. So, you know, us being able to try... Trial at farm is really helpful to be able to have these conversations. You know, we don't have the answers for that yet, but it's kind of like, this is the the state of what we know on these things that, yeah, it goes beyond promotional material. So what we're actually seeing on farms in Minnesota.
Stephen Gregg:So...
Nancy Bohl Bormann:And they
Chryseis Modderman:have Minnesota specific data. There is some data from other parts of the the country, but just like with with a lot of things research based, you want something that's that's local. You know, you're not gonna take your cover crop recommendations from Arkansas or something much different growing situation up here in Minnesota. So it's good to have good local Minnesota based data.
Nancy Bohl Bormann:You know, looking at what are the current fertilizer prices and putting in different, you know, aspects, how much is your... How much are you traveling? You know? Also, if, know, a field's already high in p or k, you're not really getting that value. You can...
Nancy Bohl Bormann:Necessarily needing that to purchase that. So keep... Keeping all those things in mind.
Stephen Gregg:I would I would say, you know, with the changing weather patterns that we're seeing, you know, especially for, I mean, any any kind of farming really, but the more that you create different buffers that allow you to have more flexibility in how you're performing, you know, how you're how you're planting your crops and fertilizing it. You know? So things like, you know, if you've been thinking about cover crops for several years or maybe a really long time but have never done it, you know, there's lots of opportunity to do that. And I think that, you know, things like, you know, using nitrification inhibitors, looking at cover crop practices are just things that are gonna make your life easier even though there is a learning curve around them, even though there will be tips and tricks. But those things will make those lives easier, we're gonna see, you know, a particularly...
Stephen Gregg:Maybe a very strange winter and spring, compared to what typically see, but, you know, the the trends are changing in general. So...
Jack Wilcox:That was Nancy Boll Borman, Kristin Moderman, and Steven Gregg, a newcomer to the podcast. They're on the manure team. Thank you so much for being here.
Chryseis Modderman:Thanks, Jack.
Jack Wilcox:Do you have a question about something on your farm? Just send us an email here at nutmgmt@umn.edu. Thanks a lot for listening, and we look forward to seeing you next time. We'd like to thank the Agricultural Fertilizer Research and Education Council, or AFREC, for supporting the podcast.