Nitrogen-fixing biologicals: What farmers should know
Hello. You're listening to Advancing Nitrogen Smart, the podcast series from University of Minnesota Extension. Here, we unpack and discuss data driven, research based information about nitrogen so that you can make the best decisions for your operation. I am Jack Wilcox in communications here at Extension.
Jack Wilcox:Joining us today, we have two nutrient management specialists. We have Dan Kiser, who you'll recognize. We also have Carl Rosen. Carl sometimes joins us on the regular nutrient management podcast.
Jack Wilcox:Today, we're talking about crop biostimulants or biologicals. Dan, let's just start off basic. What's the definition of a biostimulant?
Daniel Kaiser:Well, I think the big thing just kinda just start off here is that when it comes to biostimulants, I mean, currently in The US, there isn't a legal definition. You know, in Europe, if you look at biostimulants, they've been more active in terms of defining what they are and their use. And if you look at the European Biostimulants Industry Council definition is that plant biostimulants contain substances and or microorganisms whose function when applied to plants or the rhizosphere, the area around the root, is to stimulate natural processes to enhance or benefit nutrient uptake, nutrient efficiency, tolerance to abiotic stress, and crop quality. So it's it's it's a bit of a nebulous definition when it comes down to it, because a lot of these things tend to be a catch all and, you know, they kind of go along some of the lines of some of the things that what we call, fertilizer amendments, that are supposed to enhance they're they're not necessarily containing the nutrients themselves, but they're trying to enhance the uptake of the nutrients for a particular crop. So another definition, I mean, substances or microbes provided in minute quantities to promote plant growth.
Daniel Kaiser:Again, they're not fertilizers, they're not pesticides, they're not soil conditioners, so they kinda fall into a gray area. And, if you look at it, you know, various products, they've been around for many years. I mean, I think one of the ones that many soybean growers may have come in come across for a number of years have been the rhizobium inoculants. I mean, this is kinda some of the the similar they fall along the similar lines. But, there is a regional committee, you know, Carl and I are a part of, which is the NCERA one zero three.
Daniel Kaiser:We meet once a year and talk about some of these products that are on the market and the research that's been going on in the North Central Region, and then we've developed a compendium of non traditional products. And, you can find that if you're interested. It's, ncera103.org. You can go in and kinda look at, you know, some of the work that's that's been done.
Carl Rosen:There is a a working definition that was part of the 2,018 Farm Bill. It's not set in stone yet, but the there is a new, what's called a plant bio stimulant act, and this is being considered by Congress right now to come up with a definition. So the definition has evolved over the years, and I think, in a within the next year or two, there may be something that will will come out that will be, of more of a legal status.
Daniel Kaiser:And with a lot of these products, I mean, really what we see is when we start getting into high fertilizer prices, I mean, you know, growers are always interested in to try to do something to cut back on their cost. I mean, a lot of these products really are being marketed for efficiency purposes and, to be able to or or more actually, sustainability is kinda one of the things we we hear a lot with these products because we're really trying to get more out of our our crop yield with, less nutrient inputs. And, you know, if we look at categories of these products, I mean, there are a number of them. I mean, humic substances, amino acids or other end compounds, chitosins, which chitos chitosins are, is made are made from chitin, which essentially is dissolved shells of crustaceans. Seaweed extracts, you know, though looking at nitrogen, I mean, really, it's beneficial microorganisms, really, I think are the big ones, that we're seeing a lot in the market right now.
Daniel Kaiser:And these are free living or asymbiotic end fixers, which can be, you know, mostly bacteria, which promote nitro I mean, a lot of these, especially end fixers, they're they're fixing atmospheric end and and, providing it to the plants. And, you know, if you look at the soil, I mean, they're, I think, about all soils that contain some of these organisms. So what's really being looked at now is to try to enhance the activity of some of these things and, or even try to look at certain areas of the world where we may have situations where some of these microorganisms are more active bringing those into other areas to try to promote or increase nutrient availability. And, you know, many of these, they're applied individually or in combination. Most, I mean, are promoted as natural since they're naturally occurring in the soil.
Daniel Kaiser:But there is a degree of genetic engineering too that's going on with some of these things, particularly trying to make some of these these things work better because that's always the main issue with many of these is that, when you start applying nitrogen to a particular crop is that in many cases, the activity of some of these especially these free living end fixers decrease just because they don't have to work as hard. So that's one of the things to kinda think about on these things is that, you know, scientifically, there's a basis for what's being done in the development of these in terms of what they might do, but it's really, kinda where we get into some of the weeds is when we get into the field setting is that these things aren't always foolproof when it comes to utilizing them to provide nutrients to crops.
Carl Rosen:In terms of the, the industry, the biostimular industry, I think the big focus is on the the nitrogen fixers. It's the fastest growing segment of the industry. And it's what we call mostly the free living ones or the ones that are not necessarily, symbiotic. Like Dan mentioned, Rhizobium, that's a symbiotic relationship where it's a relationship between the the bacteria and the root. They actually are right.
Carl Rosen:They grow together. The asymbiotic microbes are more free living. They might be within the root, rhizosphere. That is the the distance, a small distance from the root, but they're not actually associated in the root. So there's many different classes. The asymbiotic ones are the ones that are being focused on right now with the with the bio stimulants.
Daniel Kaiser:Yeah. And that's one of the things even with the the symbiotic. One of the the issues that does come up is the fact that there's a trade off for the symbiotic. If you look at Rhizobium and soybean, I mean, the soybean are supplying the Rhizobium with food, or, you know, sugar or energy that the plant's producing, and then the the bacteria are supplying the plant with nitrogen. So it doesn't have to have be living in a high nitrogen or available nitrogen environment in the soil.
Daniel Kaiser:With the asymbiotic, it it's somewhat different is because, they can exist mutually, but in an asymbiotic system, the bacteria aren't supposed to have any negative impacts on a plant that's growing. So again, they're living separate from each other, working, both doing what they're doing, but not having any deleterious effects. And that's, you know, one of the things that we don't know as much about, especially some of these that are reported to be able to colonize within plants, you know, whether or not even if they're they're called asymbiotic, whether or not that's true or not. So that's kinda one of the things that when when it comes down to it, there tends to always be trade offs with some of these things. And that's one of the the things right now is where I have some doubts.
Daniel Kaiser:You know, we look at a lot of our data. We just don't see a whole lot of, widespread positive benefits from these bacterias when we get into the field settings. So that's kinda one of the things that, you know, I'm still wondering is, you know, we start looking at putting these things into situations where we've developed a natural ecosystem that has or that's balanced based on the crop and the cultural practices within the field. I mean, a lot of our microbial communities have responded to that and whether or not we can actually introduce some of these things into, some of those systems is kind of what's what's questionable right now. I mean, really, if you look at the benefits themselves, I mean, really increased plant growth.
Daniel Kaiser:I mean, that always is one that you always will see. I mean, it's kind of the the catchall for a lot of these things. If they can't prove yield, they'll tend to look at plant growth or greenness or something that have some reported effect on it. But in the end, I mean, sometimes it's it's kinda it's hard to prove or we don't necessarily see the yield increases. But a lot of these things, you know, claim that they increase nutrient uptake, they increase the availability of other nutrients, increase disease resistance and suppression, and reduce environmental impacts on cropping systems.
Daniel Kaiser:I think that's the main one right now, essentially, we're looking at, especially on these beneficial organisms, is a lot of the benefits. I mean, really looking at trying to, reduce the amount of, chemical or nitrogen fertilizer being applied, that these things should have positive impacts in terms of potential for reducing the amount of nitrogen loss. But, you know, again, a lot of these claims are vague, and they're meant to be that way because they don't always have the proof to prove that some of these things are occurring or if it they do, it's in a very or low number of circumstances where some of these things are coming to play. So when I talk a lot to growers on these things, it's really worth digging in more into some of these claims before you just buy into the hype that you see on the Internet in terms of, what these things are claiming or what they can do because, again, they're just they're not they're not foolproof. And when you you put them on, there there's a lot of other things you need to think about when you're you're applying these things that they're you can't treat it like a fertilizer where these things are living.
Daniel Kaiser:They need a little bit more care when it comes to how they're being applied and stored, just to make sure that they're actually living at the point in time where you're applying them into the soil.
Carl Rosen:Yeah. And so most of these, biostimulants are first tested out in the greenhouse or in a growth chamber under very controlled conditions. And in many cases, you can see responses there. It's when you put them out in the field where you have a lot of native bacteria and other organisms in that soil, what you add has to compete with those. And so getting that to happen is sometimes going to be a challenge for those biostimulants to actually perform the way they're supposed to or the way they have been shown in, say, more controlled environments.
Carl Rosen:And I think that's probably where the big issue is. Dan mentioned, that there are some that are applied actually to the to the leaves. They they, actually are in the the plant themselves. Those are called endophytes. And, those might have a little more of a chance to, fix nitrogen, or perform a little more effectively than those that are have to compete with microbes in the soil.
Carl Rosen:But as Dan mentioned, those endophytes may be taking up some energy. They'd have to survive, so they're going to also need some carbon, and they probably get that carbon from the plant. So Stan mentioned there is gonna be that trade off.
Daniel Kaiser:If you look at beneficial bacteria, I mean, there's there are free living I mean, I get mentioned this before. There are free living infixers already in the soil. If we look at, you know, azoosporum species, Azobacter, bacillus, or clostridium. I mean, if you look at some data, I mean, there's some data out there that says that means some of the azoosporum, in close contact with the roots of of wheat can supply roughly seven to 12% of the nitrogen for the wheat crop. And this is happening on a yearly basis.
Daniel Kaiser:I mean, if you look at your soils, I mean, we know that if you don't apply nitrogen fertilizer, that you can get a relatively large percentage of your your total yield potential without nitrogen fertilizer. I mean, our recommendations right now for continuous corn, or soil is supplying, you know, probably somewhere around half to two thirds of the nitrogen that that crop is taking up in an annual basis and that, you know, if you look at corn soy following soybean, that's probably more two thirds to three quarters of the nitrogen. And in some of that is coming from some of these these bacteria, like these free living end fixers. I mean, we know that they're there and they're having an effect. The issue really is whether or not we can add anything that may or may not already be there to boost that impact of those free living end fixers.
Daniel Kaiser:You know, I think one of the challenges, when you you look at a lot of these is that they aren't always the greatest at out competing what's already there. In the effect, some of these things that are really good at fixing nitrogen, if you look at in terms of their competitiveness, they just aren't as competitive, and that's really been the challenge. That's where been some of the the engineering the genetic engineering's been coming into play, trying to get some of these bacteria to be able to survive better in the soil and and do what they're supposed to be doing. And it's one of the things that I I still think there's a lot of challenges because, you know, you look at the systems that have developed over time in these fields, they're there for a reason. They're there because they're responding to how these fields are being managed.
Daniel Kaiser:And I think where the main thing is right now is getting around some of that with it, and I think it's why we see some poor, issues with some of these. I mean, I think the other thing too is just straight up a a lot of growers. I mean, you you just assume you get a jug of this stuff that you can just throw it in the corner of the shed and just leave it there until you use it, and that's not the case. It takes a different degree of thinking, particularly on the handling and the application, because you can kill these organisms and they're off fairly easy if you have high or low temperatures or say, you put them in with, a pretty hot fertilizer mix where now you've paid for something essentially that just has no chance of surviving in the in the soil after application. I think that's one of the keys, and I know Dave Franzen, you know, before he retired, he's talked a lot about this, and it's kind of just a general different line of thinking with many of these products.
Daniel Kaiser:Specifically, if they're biological in nature, then you would treat a lot of your other ag chemicals and and a lot of your other fertilizers when you're applying them.
Carl Rosen:Yeah. Even the pH of the water could make a difference, whether it's chlorinated. All of that can be, an issue. The other thing with, these biologicals that the infixers in particular, the ones that are not genetically modified, once you add nitrogen to the soil, they tend to, not be as effective at fixing nitrogen. So the ones that are just naturally occurring produce less and fixation when you add nitrogen, to the system.
Carl Rosen:Yeah. Those are, some of the issues that need to be, taken into account.
Daniel Kaiser:You'll see too with, some of these bacterias that they do there are other things that they they can affect, like bacterias that they do there are other things that they they can affect, like phosphorus, I mean, iron transport. You know, some of them will produce growth regulators. So, I mean, there's there's some other things you'll see every once in a while, but it's again, you you look at the industry right now, I think every company out there is looking for their special cocktail in terms of what they can sell. Again, a lot of this stuff isn't new. I mean, it's been tested for a while, so that's with, like, something like the compendium.
Daniel Kaiser:If you are interested, you just have to know what's actually in the material you're applying, because if you know the active ingredients, there is some chance that you might find some older research where some of these things have been looked at.
Jack Wilcox:It sounds like this is a complex process with a lot of variables. Do you have any suggestions on how farmers can approach this?
Carl Rosen:You have to treat them as if they are living organisms because for them to perform, they need to be alive. Some of the ones that Dan mentioned at the beginning, some of the organic compounds like humic acids and extract different extracts, chitosans and so forth, those can be mixed. And because those are nonliving, they're just organic compounds that have certain biological activities. But the end fixers are what are living organisms, and they need to be treated as such.
Daniel Kaiser:I mean, I think if you look at the fine print on stuff and the jugs that you're buying and there's likely gonna be some fine print somewhere on some of the sales literature that talks about some of the stuff, but I don't think it's gonna be first and foremost. It's always a big thing though when they don't work. It's what's one of the first things that come up is they start you know, the companies will start looking at how the growers applied them, and they'll start picking apart some of what growers have been doing, just to counteract, just some of the complaints that the product didn't work. And that's one of the things that I think it needs to be more upfront. And if you are gonna be using these things, you need to be more aware of this.
Daniel Kaiser:I mean and the thing I always wonder too is just shipping, you know, to and from where these things are being created. I mean, really, they need to be in climate controlled shipping containers. You just you just don't know. And that's one of the things when we initially looked at some of these free living end fixers, as we were looking at root digs and trying to see what kind of colonization we get. And most growers probably aren't gonna be doing this to to know what's occurring.
Daniel Kaiser:Carl, I mean, I think you brought this up at some point too with some of these free living end fixers is that, you know, some of the work initially was showing that they were colonizing early on, but they just weren't sticking around long enough where some of these things were when you started looking at later in the season, you weren't able to detect some of the these things in terms of activity. And that's kind of what I've seen with a few of these is that it looks like we get maybe a little bit of a starter effect, kinda like what we get with banded starter fertilizer with early uptake. But by the time you hit middle to the end of the season, essentially, once things get rolling and the the biological activity kicks in in the soil that, you know, things tend to get drowned out, in terms of these early responses really aren't as critical as, you know, we might think they would be just based on visually seeing them early in the growing season.
Carl Rosen:Yeah. And the amount of nitrogen that act can actually be fixed, I think that's a big question. How much assuming they do fix and they are working, how much nitrogen can you actually, reduce in terms of your fertilizer application? That's a big question. They've come up with some numbers at times, but, I think to really figure this out, growers will probably need to test some of these out on their own.
Carl Rosen:There's so many products out there, it's impossible for us to test all of them. And so I think it's one of these things where growers are gonna have to do, think about which ones they if there is an interest in them, they're gonna have to try to do some testing rather than doing the whole farm. It's gonna be you're just not going to be able to see that response unless you do a test on your own.
Daniel Kaiser:And one of the general tricks that's generally used with a lot of these things essentially is to look at the farmer's normal rate compared to a reduced rate with the product. The issue that that doesn't really address is whether or not the farmer's normal rate they're normally applying is more than what they needed in that field to begin with. The companies will be claiming wins for the product when you get the same yield between the two treatments. And really what I suggest for most growers is put a third treatment and look at that lower rate without the product because then if you're getting a higher yield with the lower rate with the product compared to the lower rate alone, then you can, I think, have some confidence that the material worked? And that's really kind of the thing.
Daniel Kaiser:I mean, I know most growers just do not wanna deal with setting up a really rigorous testing program within fields, but, you know, comparing to your neighbors or just looking at one field treated versus another field not treated, it's problematic. And, you know, I think it's one of the things we can talk about, you know, in the future in one of these podcasts is how to set up some of these trials because that's really critical with these things. And, you know, the other thing is they mean they do cost money. I mean, you look at the marketing on some of these particularly some of these products that claim to have a certain amount of n they're supplying, they're likely gonna be charging you for about three quarters or or so the value of what the fertilizer you'd be applying. So, you know, it can be pretty substantial.
Daniel Kaiser:So that's why I really would recommend if you're gonna do some testing, you know, with or without a product to make sure you have the same rate with or without. Even if you do a reduced rate, you need to have a same rate without that product. Otherwise, you just have no idea whether or not that product was actually doing anything or whether or not you could have applied less nitrogen, save money on both the nitrogen fertilizer and the the biological itself. So it's where I really recommend if you have questions. That's where people like me or Carl come into play.
Daniel Kaiser:At least maybe we can direct you to some some data that might be helpful in terms of making a decision. But, you know, realize the fact that we don't test everything and there are a lot of products out there.
Carl Rosen:Yeah. Those are really good points, Dan. I think setting up that that experiment, it doesn't have to be complicated, but just making sure you have the right treatments in there so you're comparing apples to apples. It's that's really important.
Jack Wilcox:Dan Kaiser and Carl Rosen, Extension nutrient management specialists here in Saint Paul, Minnesota. Thanks a lot for being here today.
Daniel Kaiser:Thank you.
Carl Rosen: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.
Jack Wilcox:Advancing Nitrogen Smart is proud to be supported by the Farm Families of Minnesota and corn checkoff investment through Minnesota Corn.
