UMN Extension Nutrient Management Podcast

University of Minnesota Nutrient Management Podcast Episode: “Title in sentence case”
June 2024
Written transcripts are generated using a combination of speech recognition software and human transcribers, and may contain errors. Please check the corresponding audio before referencing content in print.
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Jack Wilcox:
Welcome back to University of Minnesota Extension's Nutrient Management Podcast. I'm your host, Jack Wilcox, communications generalist here at U of M Extension. Today, we're going to talk about biologicals. We have four panelists here with us today to do that. Can you each give us a quick introduction?

Dan Kaiser:
This is Daniel Kaiser. I'm a nutrient management specialist with the University of Minnesota. I'm located out of the St. Paul Campus.

Carl Rosen:
Hello, I'm Carl Rosen and I'm a nutrient management specialist in the Department of Soil, Water, and Climate at the University of Minnesota.

Emerson Nafziger:
I'm Emerson Nafziger at the University of Illinois. Recently have done some work with nitrogen management particularly, and I'm retired and passing it on to the next people coming.

Dave Franzen:
And I'm Dave Franzen. I'm Extension soils specialist and professor of soil science at North Dakota State University until August 2nd of this year.

Jack Wilcox:
And then you're going to be retiring?

Dave Franzen:
Retiring; that's exactly right.

Jack Wilcox:
Well, we're glad to get your expertise just before you go. Dave, let's start with you. What do you recommend that companies consider as they test their biological products?

Dave Franzen:
I was fortunate or unfortunate to be the lead author on the regional work that we did a couple of years ago, and apparently the circular that we all put together and wrote went viral across the biological community. And so I've been fortunate enough to talk to maybe up to a dozen startup companies of biological asymbiotic nitrogen fixing bacteria kind of commercial products as far away as the UK. And so from those conversations, we came up with several points.

One is that the companies really need to develop a test or some kind of a method, something quick where you can actually tell if the organism is alive and functioning, in either the soil or the plant. And the second is that they need to pay attention to their logistic, that on the labels they have strict temperature requirements for the storage of these things, but that would also include the transportation.

Of course, the company from the UK was particularly interested in this because it's a long way from Scotland to North Dakota. So it has to be temperature controlled from not just at the end of the manufacturing line, but it has to go into the warehouse and it has to go into a truck and it has to go into storage, and it has to go into a truck and it has to go into storage. It goes into the distributor, goes into a truck, to the ... You see it all the way to the field because if you're outside of those temperature regimes, the thing's dead and it's not going to do anybody any good.

The third thing is that they need to be competitive, that these organisms are not going into a vacuum, there's thousands of organisms there; a lot of them want to kill and eat anything foreign that they see. And if they're living around the root slime, there's already thousands of organisms that are colonizing that space and they're going to defend their territory. So are they competitive? Are they going to win that battle?

And then finally, I think out of all of us, I think North Dakota's probably the one that has the most problems with this. We have sandy soils, we have clay soils, we have droughty soils, we have wet soils, we have soils with salt, soils without salt, soils that have high pH, I mean 8.2, and we have soils that are acid; I'm talking 4.6. Okay? And then we have quarter sections that have everything that I just mentioned in the same field. And so are these organisms going to be functional in all those variable conditions? I don't think we know the answer to any of that.

Dan Kaiser:
It's one of the things that's kind of interesting to see. I mean those comments, Dave, in terms of just what is actually being done out there in terms of the marketing side, and that's kind of what I see with a lot of these things is that the marketing trumps a lot of these other issues where, I mean, these companies have to make money and they have to get a product out there, and it's generally they're developing it at the point in time where they're marketing and selling it to the growers. And that's to me, I think one of the main issues, if these things are flushed out a little bit more before they go to market, I think there's be a far more benefit there because the thing that really concerns me is that we're in a situation where these early stage product may not be the end stage what a lot of these things come to be.

And who knows, maybe they'll work eventually, but really it's a question of whether or not you'll burn anybody out and you'll really just kind of sour the taste in terms of using these things that maybe in the future if you do get something to work, that there might be just less apt to actually use some of these things. So it's one of the things that kind of concerns me a little bit, but I'm generally skeptical on a lot of these things because it's just amazing at what a lot of these products claim. And if you look at historically, I mean biologicals, I think you could lump a lot of these soybean seed inoculants into the same categories. And we've had a lot of experience with that too, where it hasn't necessarily been a hundred percent win rate on a lot of these things. And the thing that makes me wonder too is you're also in some cases bringing in some stuff that's not necessarily for the crop or adapted to the crop.

They're trying to put something in that's not native into these soils is what's going to happen there, Dave, because I think it just hits it straight on, is that competition side is really, I think the big question mark is whether or not anything can actually out-compete what's already there because we've got these systems and these microbes already in our soils that have been developed over time just based on the systems that we've put in place for management on these fields. So it's been one of the things that I look at a lot of my trials, it doesn't really surprise me where I don't get a whole lot of, or if any, positive benefits for some of these things because there might be some small benefits, but in the end, I think just what's there tends to win out more often than not.

Carl Rosen:
All of those are really good points, both Dave and Dan. I just wanted to add one thing is even if they are alive, it depends on how you apply it and what you might be applying it with. And so sometimes you're using different pesticides as you're planting, and what's the effect of those pesticides that might be going on with these inoculants that you might be using? So that's something else to consider and needs to be tested. Also, if you're using say a starter fertilizer or a pop-up, if you're mixing this fairly concentrated fertilizer, even though it's a small amount, how susceptible are these organisms to that kind of a shock as well. So I think those are things that need to be considered and need to be tested, and I'm not sure that all the companies have thought about those types of things when they recommend these products.

Emerson Nafziger:
I'm glad Dan, that you mentioned the soybean inoculants. It's been known for over a hundred years that there are some organisms that will help legumes to fix nitrogen; form the nodules, fix nitrogen. That was really the first indication that farmers ever had that there was something like that. And the difference was that there were a lot of soils where those microbes were simply missing. So we had in Illinois, our soybeans started to get a hold over a hundred years ago. They were taking soil from soybean fields and moving it to other soybean fields, literally soil, to inoculate the seeds to get these bacteria back onto new seeds.

What's different today with these microbes, most of them are not something that was simply lacking in the soil so when you put it in there, you can see the big response. Most of these are competing with microbes that are already there. One of the differences today is that most companies developing these are claiming that they've either genetically modified these organisms or done something to make them behave in ways that the native microbes don't behave. And so that's part of the claim on it. It's something that's really difficult to ever see in action. And as the others of you have said, we're never quite sure where those microbes are and whether they're still alive once you put them in a field.

Dan Kaiser:
And I think one of the key things too is we should talk or just mention is that word asymbiotic, which Dave had mentioned, which essentially when you start looking at that versus symbiotic, which the soybean rhizobium is, they're two different things. It means essentially the asymbiotic, they kind of exist in the same space, somewhat independent of each other, which the symbiotic essentially they'll mutually benefit each other in theory. So that's one of the things with a lot of these products is essentially they're living outside of the root zone, although some of them claim to be endophytes, which essentially means that, Emerson, you could correct me, but essentially that means that they can actually get into the plant, but they're not essentially parasitic is kind of the way I put that.

So it's kind of a distinction you need to make because the rhizobium is a whole different scenario that we know that legumes, that nodulation provides a significant portion if not all the nitrogen, and that's a benefit to the plant. But the thing about it is it's also the plant has to expend some energy for that relationship too. So there's not a free lunch there. I mean there's no such thing as a free lunch when it comes to this. So that's kind of been the question in my mind.

And then the other thing too is if we are adding some of these asymbiotic bacteria, even if they would outcompete some of these other ones, essentially are we just replacing one for another in effect because the amount of food there is not going to be ... When we look at it, it's a finite amount of food where that can supply these things essentially is that it's almost like the old adage, robbing Peter to pay Paul. When it comes down to it, essentially, are you just replacing one with the other? And the net effect is even.

Emerson Nafziger:
And the fact that it's asymbiotic means that the plant has to somehow figure out that it's to its benefit to feed these microbes that are hovering around its root system. And we don't know if the plants are down for doing that or not. We know that they exude some things that some microbes can use, can feed on, but it's not like a soybean plant that is just happy to host these microbes because that gives it hundreds of pounds of nitrogen per acre that it needs to live on.

Carl Rosen:
And some of the ones that Dan mentioned that are endophytic, and that means that they actually are maybe in the roots, but they might also be in the leaves as well. As Dan mentioned, that there's no free lunch because if they're in the plant and they need to grow, they're also going to need energy. Even if you're applying it as a foliar and they get into the leaves, they're going to need to grow. So they're going to require some carbon, some biomass to produce their own biomass. So yeah, we need to be careful about what the mass balance is on some of these.

Jack Wilcox:
Emerson, we've talked a little bit about this, but have you observed that growers in Illinois can reduce their nitrogen requirements, for example, due to biological use?

Emerson Nafziger:
Well, a lot of the nitrogen that corn plants take up in Illinois is coming from biologicals. They're liberating it from the organic matter that's there. So that's a different source than we're talking about with adding these microbes and getting them to fix nitrogen from the air.

Fixing nitrogen from the air is a real trick and it's highly energy requiring, and so the path of least resistance here is that the corn plant probably gets half of its nitrogen from soil organic matter. The nitrogen is being freed up during the season by microbes that are already there. So the answer is if everything works right and these microbes are there and the corn plant exudes some of these materials and helps feed them, and they're so grateful for that that they give the corn plant some nitrogen back, that's all well and good. The problem is it's going to be awfully difficult to detect that that's happening, and the amounts of nitrogen we're talking about are not such that a farmer could just confidently say, "Well, I need 180 pounds of nitrogen for this corn crop. If I use this microbe, I'll reduce that to let's say 150."

If a farmer is using more nitrogen than his crop needs already, more fertilizer, the answer is he can absolutely reduce that and he probably doesn't need microbes to step in and replace what was lost because there was more there than the crop needed anyway. So it's a pretty delicate matter. We have not been able to find by lowering the nitrogen rates down to a hundred pounds or less and then using some microbial products and not using them, we have not been able to find that those are actually seem to be contributing to the nitrogen supply or the yield when the fertilizer amount that's been added is simply not enough to maximize yield. That was the test that we thought that these things would have to probably pass in order for people to have much confidence that they can lower N rates. And it is something that it's still out there, the reasonable test.

And at this point in time, I think many farmers could reduce their nitrogen rates, and we've been trying to talk about that for years now that our data show that in most fields more nitrogen is being used than is necessary to reach the yield potential. But it's not yet clear that microbes, they may produce some confidence, which is a good thing that producers can lower their nitrogen rates, but then the producers would be paying for that by using these products or paying for the products. We would be very happy to see farmers that are using considerably more nitrogen than the data indicates that they need in their crop to simply lower the rate whether or not they decide to use microbials to fill in the gap.

Dan Kaiser:
And I think I can echo a lot of what you're saying too. What we see here in Minnesota, Emerson is, I mean I think I've had one study where I saw a positive response where maybe I could lower the end rate by about 20 pounds, but have I ever been able to replicate that? No. I mean that's kind of the thing about a lot of these is that if I look at every once in a while you get a positive response and it's really, to me it's more or less what's that percentage probability rate that you get a positive response really is the key. So one out of 10 really isn't a glowing endorsement of a lot of these products. So it's kind of, I think the issue that on a lot of these that what I'd like to know is particularly a lot of the companies, you'll see a lot of the data on their website showing these responses, but that could be one out of a hundred, one out of 200 trials. So it isn't that these things are going to be widespread.

I think that there's probably circumstances where they'll work; it's not necessarily how these things are marketed though. I mean they're marketed to be easy to put on, so a farmer can do it without having to change much of their management and apply these products. But yeah, I mean looking at it, a couple things that I would say on a lot of these things is for one, I mean really if you look at these asymptotic end fixers, I mean as Emerson was saying, I mean really we're just trying to add additionally to the pool that we're getting from nitrogen from the soil itself. So when you start looking at it in terms of increasing yield, if you over apply N already, you're not really going to see any benefit of this product. I mean really it's not going to give you a boost or give you any yield increase unless you're under applying in.

So that's one of the things I think that growers have to think about is you have to be kind of at or below our recommended N rates in order for these things to work. So when it comes down to it then, how sure are you that these things are going to work because there's a lot of risk there in terms of potential yield loss. And that's what kind of scares me because a grower that's already kind of on the upper end of the recommended rate that might be slightly over, if they cut back and put these things on, it's probably not going to hurt them, but you get somebody that's a little bit more cash strapped that does the same thing and they see a pretty significant yield loss, there could be a pretty big hit on profitability.

So the thing about these, I mean, these products aren't free. I mean a lot of the ones I've seen, they kind of market them as a percentage of what the growers would pay for a certain rate of nitrogen, so it can get pretty expensive on some of these things with that. So again, it's kind of where you're at in what you're applying in terms of that overall risk, and to me it's a pretty big risk for particularly a smaller grower that may not have the expendable income to take a hit on yield should they under apply and these things not work.

Carl Rosen:
So one other comment related to these asymbiotic nitrogen fixers is that as you add more nitrogen, the fixation tends to go down and so you may not be getting the benefit from them if you are adding too much nitrogen to begin with. Now there are a couple, maybe one product out there where they've genetically engineered the microbes so that it will fix under high end conditions, but most of them are not genetically engineered and so they will shut down when there's high nitrogen in there. So it just complicates the situation. So you really need to be at lower end for those microbes to work.

Jack Wilcox:
Carl, is there new research out there that tells us anything about biologicals effectiveness?

Carl Rosen:
Well, I think the first thing I want to mention is that there are so many products out there that we can't possibly do testing on every single one of them. And so it's going to be up to the grower, if they're very interested in using those products, to try them out on a small acreage first to see if they work. But having said that, I have done research on some of these products recently. In general, I don't see yield increases, but in one study I did measure the nitrogen uptake by the plant and concentration in the plant, and we did see a significant increase even though there was no yield increase. So it told me that, yeah, this product is actually doing something, maybe didn't increase the yield, but it was getting more nitrogen into the plant.

And so there are some situations where we can actually measure things, and I think Dan said that he found a situation where went one out of 10 trials, he did see a positive response. So it's one of these things we have to find the situation where it will work, if they do work, and then try to identify those conditions where you might be successful. But as I said, it's difficult to test every product, and so if you're really interested in using one, you're going to have to try look around for data, but don't rely on testimonials. So try to get your own data or look at replicated research trials that might be out there. And I don't know if anybody else in the group might have some more additional data to add to that.

Dave Franzen:
I think it's really important, like you said, I think it's important for farmers to be curious. I mean, it's okay to be curious. I mean the reason that we as a group, 10 researchers, came together in November a few years ago and decided that we were going to work on these things because we were curious. And so it's just natural for farmers to be that way, but you just shouldn't just jump out of the meeting and sign up for 5,000 acres is something that sounds good. So I don't think I missed anything, but right now probably the premier On-Farm Research Network in the country is conducted at the University of Nebraska-Lincoln. Just Google University of Nebraska On-Farm Research, you'll find it. They have a wonderful website that has YouTube tutorials on how to set up replicated strip trials.

And this is really important because some farmers will just go out and compare this field with, this field without. That's not an experiment, that's just an observation, where they'll divide a field in half and do it on one side and not the other. And that's not an experiment either. So there has to be replicated strips. And the Nebraska site is wonderful too because they actually have a very, very simple statistical program that anybody's grandmother could use in order to figure out if what they're seeing is really real or not. And so I'd really, really think that people could take a look at this. I think more and more states will get their own On-Farm Network. The one in the Nebraska is Extension-led. Iowa has two. They have one from Practical Farmers of Iowa, and then the Iowa Soybean Association I think also has one. But I've looked at all of those and to me anyway, the University of Nebraska is just universal; anybody could use that material.

Emerson Nafziger:
Well, something like this is always going to be really difficult to see a response from, and that's part of the difficulty. If you inoculated soybeans for the first time, you can actually see nodules. We don't have anything equivalent to that in corn. Maybe we ought to hope that they'd come up with some kind of, the plants glowed orange at night or something if they were fixing nitrogen.

One of the other novelties today is that we have this drive for sustainability and anything that's not chemical nitrogen fertilizer is going to be given a certain amount of credit as being more sustainable. A lot of times these are okay approved for organic production, and so products like this can take on added value in people's minds because it's not chemical fertilizer. And so the burden to actually prove that something like this works is one that's going to be really, really difficult to meet for individual farmers or for groups or for companies because we're out there in the wide open world, it rains sometimes and sometimes it doesn't, and all sorts of things are going on in the plants and soils every day.

And so if everything were controlled out in the field, we would probably be able to produce something like this that would be a real, that we could depend on. But we're in an environment, a productive environment. Most farmers in the states we're talking about here are getting fairly high yields without using these products and some are using more nitrogen already than they'd need to, and if they'd cut back and used a product instead, they would view that as a success. And environmentally it might be a success, but ever putting a number on products like this in terms of their success rate is going to be very difficult. And one thing that will make them possibly give them a leg up will be some sort of subsidies or something that rewards sustainability and says, "If you'll cut your nitrogen rate back by 30 pounds and use this product, we'll pay you more for your corn," or something like that.

I think that part of it could be positive, but today's venture capital and this looking startups and so on that I think the main reason we're seeing so much of this now, hundreds of products under development to do pretty similar things out in the field, and I don't know if we'll ever have a reckoning, a list of things that have been proven to work as advertised, but my suspicion is probably not. We almost have to just come to the point where we say, "Well, we accept that it works, we're going to use it," or, "We're not sure it works and I don't think we want to use it," will be what a lot of farmers come to.

Dan Kaiser:
In your comments, Emerson, on that sustainable or sustainability is interesting, particularly as Carl mentioned that some of these products are considered or would essentially be genetically modified organisms, so you kind of balance the two that they don't seem to be good things together when it comes down to it. So I think that's one of the things that you kind of have to weigh on some of these things. The other thing is too, I've had some comments from some people talking about things like this essentially completely replacing fertilizer, and I don't see that happening right now.

It is interesting when you look at corn because if we look at just our current MRTN data, our maximum return to nitrogen database that we have for Minnesota, I mean anywhere from 65 to 75% of our yield is produced by the nitrogen that's in the soil itself here in Minnesota. I think it's probably slightly less for you, Emerson, maybe a little bit more for you, Dave, just because of organic matters. So the fertilizer we apply really isn't accounting for that large percentage of the yield, but it is important, and looking at these products, I don't think there's any way we're going to be able to completely replace that even though some people think that with some of these.

So just looking at it, I mean, just testing I think is key to growers, and really I think, Dave, I mean those resources you gave I think are just spot on. And just having growers look at how to properly set up trials, because I think that's just really key to make sure that you're getting good data and to make an accurate decision on whether some of these products work.

Dave Franzen:
And with the nitrogen fixers, it's really important. I've heard somebody that was, I don't know, hawking something and they were saying that the farmers should use pretty close to the nitrogen rate that they already use in order to test them. Well, that's completely wrong. They need to test it on a strip that has about half the nitrogen that our nitrogen calculators would tell them to use. And then if there's going to be a response, you'll see it. You'll never see it if you're up around 160, 200 pounds of nitrogen, you'll never see anything. So it needs to be done about half rate. If they put the strips out of half rate, they'll see something if something exists, and that's the way they have to do it.

Jack Wilcox:
Dan, could you sum up what should growers watch out for when considering companies' claims about their biological products?

Dan Kaiser:
Well, the main thing, Jack, I just look at the data that's presented because there's this industry-wide standard where essentially they'll compare the farmer rate to the farmer rate or to amount of nitrogen less than the farmer rate with the product. That seems to be the standard comparison to show whether or not these products work. And what I've really been stressing to a lot of growers is you really need more treatments than that. And that's one of the challenges is that's why it's a lot easier for me to do research where I can screw up, where I can make bad decisions than having a grower do it on field scale. One, because I could do it on a smaller scale.

Dave and I were interviewed, this has probably been a year, year and a half ago, I think, and it was kind of some back and forth between some company people and us and some comments on our comments. And I think one of the comments from one of the groups, the biological groups, is that a lot of our trials are small plot trials and that they need larger trials really to show that these things work because we know that measuring yield data is noisy, but the problem with a lot of the larger trials is you just can't put the rigor to it that I can do it, especially when I have multiple nitrogen rates, up to eight nitrogen rates with and without the product. I mean that's really what you need is you need what Dave said, rates that are far less than the suboptimal.

I know that was another comment we had from the researchers that one of the companies was claiming that we need to test a product with the recommended rate minus 40. Well, the problem is do we know what that recommended rate is for a particular field? We know that's a moving target. So the easiest way for me to do it essentially is to have no nitrogen up to what I would recommend with some rates above and below, with and without the product, and test it that way. Because really if it's going to supply 20, 30, 40 pounds of nitrogen, it should do that no matter whether I have zero applied or I am 30, 40 pounds from the recommended rate on that. So there's really nothing magical about that.

I mean, I know why they do that. I know that just talking to somebody I knew I've known for a long time from the industry, I mean that's one of the things that he brought up is especially when you've got to pay for these products, the easiest way to do it essentially is to have them cut their rate. They get the same yield where that rate they're cutting is enough to pay for the application and the cost of the product itself, and since they get the same yield, no problem. But it doesn't mean that this products work.

The other thing that was found interesting too in some of the comments is one of the claims that we only focus on yield, which I kind of chuckle a little bit because I started thinking, what do growers care about? Carl, your comments about getting some additional nitrogen in the plant, they're not going to get any more money from the elevator for that. And that's one thing I've seen with some of these products is it looks like what we get what we call starter effects, where we get early in the season, there might be more nitrogen in the plants, but you look at the end of the season, there's absolutely no difference. So while there might be something there, I mean really it's yield pays the bills. I mean it's got to have at least be able to either reduce the nitrogen rate that you apply and cover the cost of the product that way, applying less commercial fertilizer in with the product, or increase yield, which again isn't going to happen if you're already at or above the recommended rate on that.

So the main thing I think is go to places like the University of Nebraska-Lincoln, their website, and just learn out how to set these trials up. You can't compare one field to the other, or maybe your neighbor doesn't do what you're doing and you're comparing your yields to them. It just doesn't work. You can't split fields. You have to have these things set up to make a valid comparison when you're doing it. And it's hard to tell, especially with the data you're reading, how the trials that generated that data were set up. But really I just look at the treatments and what they're comparing and just see is it an apples to apples comparison with and without the product because that's really key to really just check and see if these things work.

Carl Rosen:
Yeah, I'll just make a plug for the NCERA-103 as well as a place where you could look at data, maybe not as comprehensive as the Nebraska site, but it goes back to the 1980s. These biologicals are something that's been around for a long time, and so if you want to go historical and look at some of the older data and some of the newer data, the NCERA-103, if you Google that, you can get to the site and there's a compendium of some of the trials that are done there and as well as some of the other fact sheets that have been produced. So I think that's another place to look.

The other thing I want to emphasize, and Dave and Dan said this, but when you're comparing at say half the rate, you have to also include the product at half rate, but also go to half rate without the product. Because if you don't, if you just do the product with half rate and then compare it to a full rate without the product and there's a difference, you don't know if it's due to the product really. You just know that half the rate is okay with the product, but you don't know what would happen without that product. So you need to do both with and without the product. Very important at all rates.

Dan Kaiser:
Yeah. And I do want to thank Emerson and Dave. I mean they've been on the, Emerson more recently on the NCERA-103; Dave, you've been on it for a long time, and kind of unfortunately I've become the old man on the committee at this point moving forward. But that committee has done a lot of good work in terms of trying to organize data. And that's one of the things, whether it's these biologicals or any other of these fertilizer amendments that I think it's ncera103.org is the website for that particular thing. If you are interested in going in, you can look at some of the data that we have collected.

The main thing with a lot of this is, when we start talking about a lot of these products is you see a lot of variation in trade names, and it's amazing at how much a lot of these things, it can be the same chemical compound or a variation that tend to reinvent themselves over time. And I think if as a grower you've been farming for a while, you've kind of seen that with a lot of these products, they tend to ebb and flow and they'll kind of come in and go out of the market; they might have different trade names on that.

So the big key on that, I mean even with some of these biologicals, if you can figure out what the organism is, that's really one of the things you need to do is you could probably find some information going back quite a few years on these things because these things aren't new. I mean, they've been around for a while. The big thing right now is the fact that gene sequencing's a lot easier, so it's a lot easier to see what's in the root zone so you can kind of sequence what's there and then try to figure out what it does.

And if you look at all these products, I mean, they tend to have some sort of shred of scientific, well, most of them do, I would say, principle behind them, but when you get them in a biological system, all bets are off. I mean, that's one of the things about this is in a sand culture, something that's more controlled, maybe these things could behave where they don't have to compete with anything else, but just these biological systems that we have in place are so complicated that predictability of these things, what's going to happen once they hit the soil, it's really hard to say.

Jack Wilcox:
Thank you all very much for joining us. Dave Franzen, good luck as you enter retirement, and Emerson Nafziger, thank you for coming out of retirement to spend time with us. And then as always, Dan Kaiser and Carl Rosen, thanks for being with us here today.

Before we go, if you have a question or comment for one of our guests, or a topic you’d like discussed in a future episode, please email us at nutmgmt@umn.edu. Thanks, and we look forward to hearing from you.

Alright, that about does it for this episode of the Nutrient Management Podcast. We’d like to thank the Agricultural Fertilizer Research and Education Council, or AFREC, for supporting the podcast. Thanks for listening.

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