Subscribe
Share
Share
Embed
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 Advancing Nitrogen Smart, the special podcast series from University of Minnesota Extension. I am Jack Wilcox as always in Extension Communications.
Jack Wilcox:Today, we're going to talk about land management, and I'm here with three Extension educators and specialists. We have, of course, Brad Carlson, educator from Mankato Daniel Kaiser, nutrient management specialist from Saint Paul. Also from St. Paul joining us today is soil health specialist Anna Cates.
Jack Wilcox:Brad, start us off. Let's talk about the effects of land management on nitrate loss to water.
Brad Carlson:Well, there's a lot of different ways you can go with this discussion. We'll hit a few of them here, but I think the overarching thing we do need to think about when we're talking about trying to reduce the amount of nitrates in water is that a lot of the methods to do this are sort of additive and they kind of play on each other. You know? And so one of the things that we we have to start with is always managing our nitrogen fertilizer correctly. Because if you're you're going way overboard on that or you're doing some other practice with nitrogen fertilizer management, it can mess everything up, and and then it gets be difficult to try and and get to your final objectives.
Brad Carlson:And and, you know, so really when we talk about land management, what we're really trying to do is kind of build on off of the back end of already managing nitrogen in our crops properly. So one of the ways you can kind of think about this is is soil health community has what they consider the five principles of soil health. So one easy way to break this down is looking at those five principles of soil health. And so those are soil armor or protecting the soil, minimizing the amount of disturbance in the soil, which has the effect of building soil organic matter and hopefully increasing biological activity. Plant diversity on the landscape, continual plant presence on the landscape, then finally, livestock integration into the whole system of agriculture.
Brad Carlson:We're gonna focus on just a couple of these things today. So, Anna, these how long have these been around? Because I've when I was in graduate school, we talked about this is soil quality, and somewhere along the line, it changed to soil health. I don't recall these five principles being out there. I'm not exactly sure when they came into being probably about the time that's the term cell health probably came into favor.
Brad Carlson:What what's kind of the history on the evolution of this stuff? And I think when we're talking nitrate reduction to water, not all these are created equally either when we you know, on any given farm or any given point on the landscape.
Anna Cates:Right. So soil health does have a relationship to water quality or nitrate losses, but a lot of it is around just protecting the surface of the soil, keeping the soil from eroding, keeping it in place, and building biological activity in it. So these principles, I couldn't say exactly how long they've been around, at least twenty years I would say they've been widely used. And I'm sure you knew about the principles in some way when you were in grad school Brad, but they just weren't called the soil health principles, right? So they're not new practices that are coming up with soil health.
Anna Cates:But if you think about a lot of them are trying the soil where it is, so they actually tend to have a larger impact on phosphorus movement in the landscape since phosphorus is sediment bound more often.
Brad Carlson:And I think that's a pretty good point. And frankly, it's worth noting that the end goal of soil health goes beyond water quality. I mean, we're here talking about a water quality issue, nitrate loss into water. So not all of these things are gonna be created equal in terms of their impact that they have on on nitrate loss to water.
Anna Cates:I will say socially, right, so farmers who are thinking about these principles are often paying a lot of attention to management. Right? They're detailed managers, and so they're likely gonna be detailed managers when it comes to nutrient application and timing as well.
Brad Carlson:Yeah, that's probably the case. We see some of those studies, know, for instance, you know, like the Minnesota Ag Water Quality Certification Program talks about, you know, the participants in this program are more profitable than participants who aren't. And sure, there's something there as far as being more efficient with your management, but it also speaks to just being a better manager overall, and and that's probably a big part of this, you know. So when it comes to what we say soil armor and, you know, you as you just mentioned, a lot of this stuff is it's got multiple objectives, you know, in terms of reducing erosion, phosphorus loss, and and so forth. So tillage is probably the first thing a lot of people think of.
Brad Carlson:We don't have a really great track record of success with no till in Minnesota, no till soybeans to some extent, but but no till corn has kind of struggled other than in a few places. And in some some instances, farmers are using it with its full acknowledgment they're not going to achieve full yields and so forth. But when it comes to whether tillage has any implications on nitrate loss, There have been some studies, and and I know one that I saw from Iowa shows a 30% reduction by switching to no till. I would tell you my professional opinion is I can't figure out why that would happen because I see no reason that it would affect the more water percolating through the soil.
Daniel Kaiser:And I don't know. I mean, looking at you know, one thing always comes up when I talk around the state is some of North Dakota's recommendations too, where they've got Western North Dakota recommendations and no till of lower nitrogen rates and think some crops, mainly the one I think I know of is spring wheat. Midnight corn. So it's it's really hard to say in that circumstance when you're in a more arid area. You know, is that lower recommendation, you know, truly just the no till?
Daniel Kaiser:Is it something else the no till is affecting? You'll say, you've got more water holding capacity. You might have a little bit better yield potential or, you know, potentially more mineralization because there's moisture there to help the microbes stave up mineralization. I mean, in terms of the the reduction, I mean, the only thing, Brad, that I can think of is if you are in a more saturated situation, you might have more denitrification in that situation. So you could have a little bit more gaseous loss that way with it versus, downward loss because if you're in a situation with no till, technically, you should have better soil structure.
Daniel Kaiser:So hopefully, you should have better percolation drainage through the soil that it would carry, I mean, nitrate theoretically. I mean, that's all theoretical. But, but, yeah, I mean, mostly the tillage, I mean, a lot of times, I think a lot of people will just focus on, you know, it's an increase in organic matter content. And I mean, that's really the main benefit of it is, you know, we know from, you know, past history, if you go back to essentially when a lot of these prairies were broken first, that we've seen a pretty stark decrease in organic matter, and a lot of that's because of the oxygen that's getting increased in into the system when you do tillage. I mean, it's gonna hasten the breakdown of organic matter, but also loss potential.
Daniel Kaiser:And I think, you know, really in Minnesota, a lot of the no till farmers are probably looking at more areas that are more prone to erosion or some other losses that, there may be some other impacts. And it's kind of an interesting when you start looking at it, just the interaction of all these things in terms of of decisions. It may not just be a just a straight up effect looking at loss or looking at changes in what it may affect further nitrogen requirement.
Brad Carlson:And that's an interesting point because the part of the state where no till corn has been most successful is actually in Southeastern Minnesota. As per a topic that we've discussed previously, some of some of your analysis, Dan, shows that we probably need less nitrogen in that part of the state also. And so, you know, it kinda goes back to what I started with. If you're using nitrogen management properly, then then things kinda build on each other.
Daniel Kaiser:And that's been historical. If you look at the guidelines, and most of that's because of the type of soils down there, the silt loam soils that they have, They tend to be better drained, better aerated. So if you look at a lot of the nutrients that are affected by mineralization, I mean, nitrogen sulfur, theoretically if you look at it, then there should be a higher mineralization potential. So if you go back into some of our crops with table guidelines that aren't specific corn recommendations where we don't factor in any sort of mineralization potential they've always had even though those soils are lower organic matter at that 3% or less which tended to always put them in the higher nitrogen requirement. Those the Southeast specifically were always told people to bump it into the high and be just or the in the the situation where you need less and because we tend to get a higher mineralization potential out of those soils.
Daniel Kaiser:So, you know, it's an interesting interactive system where all this stuff works together. Mean, and you know, and with a lot of these soil health things, mean, it's not one factor probably that if you're seeing some benefits, it's just that the whole just the whole system approach, you know, as it would in terms of what those benefits were, there could be some some interactions that that are more important than just a single factor itself.
Anna Cates:Yeah. I think there's a lot of when you reduce tillage, there's a change in the timing of nitrogen mineralization because you're changing again how water enters the soil in the spring, and that time of year when you kind of have potential for a lot of leaching losses, but if you are letting water in more slowly when you have a lot of residue on the surface, like you say, it could be denitrifying or it just is is changing how the biology's processing it. And then similarly, if you have, you know, maybe cooler soil temperatures later in the season because you have that residue on top, then maybe that's actually more favorable for biology on a 100 degree day than it is in a, you know, flat black field that's baking at a 100 degrees.
Daniel Kaiser:The residue itself too could be causing something too.
Anna Cates:Yes, definitely tying up.
Daniel Kaiser:And I guess what you asked could be some tie up of some of the nitrogen.
Daniel Kaiser:Right. I mean, that that's something we've we've been trying we've really not done a good job, and I don't mean that to say we've not been we've not been doing our job. But, I mean, we really haven't been able to nail down what really is going on with immobilization with with residue, you know, in terms of being able to predict it and know what how much is happening, when it's releasing, what kind of a pool the nitrogen is going in, is it tending to you know, there's some indication that some of it's turning into kind of more of a permanent pool in the soil versus something that's more readily mineralized and and lost. And and so the fact that we've got these high residue levels right up at the surface, definitely, that could be playing a part in this. And I think the other thing, you know, getting back to the additive effect of other practices, I mean, if you're doing no till, you're probably not putting your nitrogen on till spring. So, you know, that that's going to have a positive effect also.
Brad Carlson:Think, you know, in general, you know, one of the principles we talk about with nitrogen losses, the less time it's out there, the less likely it is to lose it. You know? We try to minimize loss, and in a lot of cases, a fall application, we say, in general, is fine, but the bottom line is if it's not out there, it can't be lost. Right.
Anna Cates:Yeah. I think you're right. I think there's a lot more springing application and side dressing and liquid fertilizer use among people who are trying to minimize disturbance.
Brad Carlson:Oh, I go back to the very beginning of my career, and actually it sort of predates my career. The first thing I did professionally was I was an intern at the Southern Experiment Station in Waseca for Giles Randall starting in 1990. And at that time a lot of people are pretty familiar with our drainage plots that we have at Waseca. At that time, we actually had a second set of drainage plots. Those have since been removed.
Brad Carlson:I don't remember exactly when, but they've been gone for quite a while now. However, the second set of drainage plots, and if you're familiar with where those are at Waseca, the other set was kinda right on that fence line immediately to the the west side on on what they call the referred to as the Preb Farm. And that trial, when I was there, was was looking at the effects of the tillage on nitrate loss. And so we have the data from that. It's old data.
Brad Carlson:I mean, we're talking 1982 to '92. And so it's like, you know, when I was there in the summer of nineteen ninety and ninety one, and just a tiny little bit in '92, I was there right at the tail end of that. But if you look at the data from that study, it shows virtually no difference between and this was continuous corn between the area that was moldboard plowed and that was no tilled. And so, you know, they were at that time, I know they were sort of speculating like, well, if we can see a water quality improvement, maybe that offsets some of the losses that we have from profitability on the no till, but in reality, they saw no water quality differences and huge losses. I mean, we know that continuous corn no till in Minnesota is just a no go zone.
Anna Cates:That's a really hard one, but the yields for our corn soybean rotation tend to be if lower in corn, the profits can be comparable. They're not as as competitive as a strip till system, but you don't have to invest in a strip till rig. So I think no till corn profits are looking fine these days with better planter technology and ease of applying fertilizer later in the season.
Brad Carlson:And that's a really good point, and and we continue to see a lot of advancement in planter technology. In fact, I was at a a person who was dealing with planter attachments and accessories here just this spring, and I was quite impressed with some of the stuff that's coming down the line. I I think we're we're we're really we're beyond the the the point where we're just dropping a seed on the ground and covering it over and hoping for the best. There's lot that's going into planter technology these days. Let's talk a little bit farther here, though, on this tillage side.
Brad Carlson:You know, we mentioned the fact that one of the objectives of reducing tillage is that we hope that we're building soil organic matter. We know that low organic matter correlates to less mineralization, high organic matter doesn't always correlate to more nitrogen. And we've we've kind of stressed that point a lot in Minnesota because a lot of the places where we see our higher organic matter are wetter places that are gonna be anaerobic, and we're not gonna necessarily see the nitrogen coming to the crop. You know, we talked a little bit about the the immobilization part. One of the things that I like to stress, though, in all of this is that the breakdown does eventually reach an equilibrium.
Brad Carlson:And, And I know a lot of farmers back when for instance, the rootworm technology came along, I don't know how long ago that was now, fifteen years, maybe twenty years already. And we were hearing, oh, we gotta do a whole lot more tillage out there because we've got all this more residue. And my comment was always, well, if if it really wasn't breaking down at the speed you were telling it, it'd be three feet deep now. So so clearly, residue does reach some kind of an equilibrium in terms of its breakdown.
Anna Cates:Yeah. It definitely does. And like but like you say, it's just not a, you know, 25 of that organic matter is mineralized every year. It it again comes down to timing, like when you have good conditions for that decomposition to occur, when you have good conditions for microbes in a certain local environment. Something I think about with a no till system where it has good structure, good structure usually means more big pores and little pores.
Anna Cates:And when you have that, you always have some dry places and some wet places in the soil, so you have more chance for some microbes to be in ideal conditions because you've got a variety of pore sizes. In a heavily tilled system, you have a lot of small pores. They work great in the spring, but if it rains a lot, then they clog up.
Daniel Kaiser:Yeah. And as Brad said too, mean, I've thought about this a lot over the years just in all of the drive time I had just back and forth between meetings, just looking at organic matter. And I know there's the belief out there looking at variable rate that organic matter sometimes gets utilized for adjusting rates. And as Brad said, I mean, if you look at it as a whole, I mean, across the state of Minnesota, the prairie potholes areas where we tend to have, you know, five, six, seven, eight, means really high organic matter levels. Those are soils a lot of times that are wet and and really are impacted by denitrification.
Daniel Kaiser:Although if you deal with, like, an organic soil, I know, Brad, you got some in your area, some of those growers don't apply anything. So there are situations there that, that you would get a high amount in. I think within a field setting, I mean, if I just took a field, say, in Southeastern Minnesota and looked at my organic matter map, I think you you might be able to track a little bit, you know, where you can make adjustments based on organic matter within a field, but it it's not a perfect scenario, and we've never been able to come up with any good set values. I mean, obviously, we can use rule of thumb to to figure out and something I think we talk about in the in the entry level nitrogen smart stuff. The fundamental section is about how much nitrogen we can mineralize per acre, per year, per organic matter.
Daniel Kaiser:So, I mean, you can calculate those values, but it isn't perfect scenario. And the thing that I always think about too is, you know, you look at those higher organic matter areas, a lot of times, I think growers might think, okay, these tend to be higher yield potential areas because it's not just organic matter. If you look at that where you're hasting mineralization just because higher organic matter levels, a lot of times, these areas, you might just be better for overall crop production. The crop's gonna grow better, develop bigger roots, maybe have a better accessibility to the soil, that it it said it just isn't simply that the organic matter is, the only factor there. That's the thing.
Daniel Kaiser:In a lot of cases too, I look at, you know, some of the within field situations that those areas may, you know, indeed need less nitrogen, just as a whole, even though the yield potentials are higher. And this is kinda said where it gets to be a really sticky scenario because you kinda start seeing this interaction between mineralization potential, between yield potential, and, you know, so just some of the thoughts on how to manage nitrogen. It's not just a really a clear picture of what's going on. So that's why I just really don't suggest utilizing organic matter that much, especially if you're trying to just calculate nitrogen out of it because it's it's not just simply a linear function with organic matter and, you know, we we can see some some other effects that could come into play, which you may, as Brad said, see lower potential availability just because other things like denitrification in areas that tend to be really high.
Brad Carlson:Well, I think I think adding a ripple of complexity and and probably problem to this too is what the timing of that breakdown is because we frequently see, you know, yellow corn and corn on corn, and we we don't attribute it to necessarily not having enough nitrogen. We attribute it to the nitrogen that there got locked up in the decomposition process. So you can say it's there. It's not available.
Brad Carlson:You know? And so some of that, Anna, turns into a soil health issue too because the speed at which that organic matter decomposes and that nitrogen re releases in the soil is being affected by the the biology and and what's happening in the soil too.
Anna Cates:Yeah. That's right. So we always because of the potential for locking up nitrogen and residue, we do recommend making sure you have starter nitrogen in these systems where you have a lot of residue because it's likely to be taking nitrogen from the soil to process that residue. So it's likely to be a little bit of that. But because so many different organisms are part of the decomposition process, part of the release of plant available nitrogen from your residue or from your soil nitrogen pool, it's just really hard to pinpoint.
Anna Cates:This is the moment. This is the organism that is gonna drive an exact release of a pound of nitrogen to your corn.
Daniel Kaiser:And one thing that I just thought of too, you know, Brad, you mentioned this, but the thing of the issue we have here in Minnesota is it gets cold. I mean, it's cold in May. You know, we can be somewhat cold into early June, and that will affect mineralization potential. So one of the things that when I start looking at the fertilizer we apply, I mean, a lot of times when I look at that where that's important, that's really more critical early in the growing season. If you look at a lot of the data, we've looked at late season nitrogen applications, and there's been a lot of failures where we've really seen no yield increase.
Daniel Kaiser:And I don't know. It's probably been ten, fifteen years ago. I mean, you know, 2015 or a little bit earlier, there was a lot of emphasis on late post tassel nitrogen because if you look at uptake, I mean, corn is taking up, you know, twenty, thirty pounds past hassling. It slows down quite a bit at that point in time, but it is gonna take something up. And so there is this big, you know, interest to start supplementing late season with the high clearance equipment, and we just haven't really seen the benefit.
Daniel Kaiser:And I think a lot of that's because mineralization for us will start kicking in. We have higher organic matter, and, you know, at that point in time, then you really just don't need it. So, I mean, fertilizer, I think, is more critical for us early on. That's when we need it just because, I mean, really all that crop has at that point in time when the soils are cold are, you know, the inorganic end that's carried over and what fertilizer we've applied. So that's the thing that makes us different, and that's the thing you just really need to be careful when you're looking at data.
Daniel Kaiser:If you're in Minnesota, I mean, look at where that data's coming from because, you know, the environment temperature, you know, specifically how warm things are in the spring, I mean, really can factor in a lot in terms of some of this this information that you're getting and some of this biologic effects of biological activity.
Brad Carlson:Yeah. And and, you know, biological activity, I have always felt going way back to when I was an undergraduate, that this was really the secret that's left to be unlocked. And I I I've got, for instance, in my in the advanced nitrogen smart curriculum that we use on reducing nitrates, I've got a comment, it's a theory. I don't mean it's a theory that it exists and that it's real and is important. I mean is we still haven't been able to quantify this.
Brad Carlson:I mean, we can't we can't you can't send the soil sample out for a test, and then they give you some biological index, and then you can use that number for making management decisions. We all you know, we know we want more biological activity out there, and we know that it leads to better outcomes, yet it's been so difficult to pin that down. Have we made any any strides in that area, Anne? I mean, I mean, there there keeps me all these exotic soil tests out there, and frankly, I've been a little disappointed in a lot of them.
Anna Cates:Right. You can kind of attack it in two ways. You can try to measure the pool of nitrogen there with a bunch of different organic nitrogen tests. There's a lot of ways to extract organic nitrogen from the soil. Marshall McDaniel has some great work looking at some unusual extracts and showing that they do predict nonresponsiveness in a nitrogen rate trial.
Anna Cates:And the and the other thing you can do is try to estimate soil activity, which is kinda what you're saying. But then I think you run into this timing problem because I can take a sample in May and bring it into the lab and test the biological activity by, you know, incubating it essentially. I can say something about how fast things are processed. But that doesn't get to, is it gonna be wet? Is it gonna be dry?
Anna Cates:Is it gonna be warm? Is it gonna be cold? And is it gonna be that way in the space in the soil where your plant roots are. Right? That's so you can take some measurements, but the pools aren't exactly correlated into what the plant takes up, and then the rate of transformation is just so affected by so many weather variables that we can't we aren't very good at predicting.
Anna Cates:Sometimes we get as good as, like, oh, you know, point four correlation, or we've improved our nitrogen rate. Know, we're able to get it a little bit tighter than we were, but it's not great. It's a it it can only slightly improve on just a straight inorganic nitrate test. So I feel like we should say some of the tests that are out there, the Haney test, they have that same approach. They measure both biological activity and the water extractable organic nitrogen and carbon, and they use those to estimate your nitrogen availability.
Anna Cates:And it is it is an estimate. It's it's probably not that different than you would get from doing your pre plant nitrate test and making an estimate based on that.
Daniel Kaiser:And a lot of the data I've seen when we've tested a lot of these, I mean, those tests do tend to correlate very well to the minimum yield produced in the field out nitrogen, so it does very well in terms of of giving me the overall yield potential, but then that difference between that and maximum yield is where we tend to have problems. And that's kinda where I struggled to find something to to look at that. I mean, really the only thing that I found that essentially is the minimum yield potential does somewhat relate to what the overall nitro requirement might be. But yeah. That's the thing I've struggled with because, you know, it's it's like any I mean, a lot of like the Haney test, I think it's it's somewhat of a mass balance type system where essentially they're trying to predict the total number to subtract from your requirement where most of the soil tests I deal with are all indexes.
Daniel Kaiser:So it's looking at just the general risk that you're gonna be short at that point in time. And that's, you know, when you're doing as as you mentioned, Anna, you're taking a single point in time, that's where it becomes problematic because I think, you measure it in situ, maybe it'd probably be better at that point, but you take a soil, you dry it, you send it to the lab. I mean, a lot of times, say when we ran the Solvita test, which was that c o two burst test, I mean, it related always just entirely to organic matter, and there's almost a linear relationship between the two and, as Brad said, you're in the field, I mean, it could be a whole different scenario at that point in terms of what's happening there. So that's, you know, kind of the problem with that when you're trying to predict the absolute number that that it works we're using it more of a risk assessment and an index works tends to work a lot better for a lot of the soil tests.
Anna Cates:And we just need so much more data to use these as indices. We just have, you know, a few dozen, a few 100 data points using the Haney test or those kinds of extracts. It's not enough to make them an index yet.
Brad Carlson:Well, and my my big question has always been speciation because, you know, they we talk about the fact that there's more living organisms in a shovel full of soil than there are, know, human beings on the planet Earth. And and so what's out there already versus what is there that we want to have out there, you know, that that's the big question for me. Because clearly, there's plenty of my of microorganisms already there, but they're not, obviously, not producing the outcomes we want. And so do we know what we do want, and do we have any clue how to encourage those over what's our native population out there. And, Dan, some of this crosses over into some of the work with the biological additives, and you've worked with some of that that's tried to do that.
Brad Carlson:I my history, you know, I go back to, like, twenty five years ago, we had farmers doing what they called compost tea, and they were just taking compost, soaking it in water, setting it out in the sun, and then just spraying that water on the field. And we are always like, yeah. I'm sure there's some microorganisms out there, but compared to what you've a, we don't know what they are, and b, compared to what's already in the field, how do you know you've done anything at all?
Anna Cates:Yeah. There's so many organisms out there, and we don't know how they'll contribute to the processes we want at the time that we want them. So I think that the efforts to understand, like, all the DNA of microorganisms in the soil, they don't give you usable information. I think it might be useful to look one step up or a couple steps up in the food web, thinking that when nitrate is actually released within the soil food web might come from when a slightly larger organism eats a smaller organism and releases some extra nitrogen. A nepotode has more nitrogen than that larger organism can use.
Anna Cates:So I think those predators could be organisms that actually are useful because they're sort of specifically releasing plant available nitrogen. Of course, you know, right after that predation, that nitrogen could be taken out by something else. The food web's super complicated. And I I agree with you that adding organisms is just an iffy proposition. I mean, some of the research on compost and certainly manure, you know, show that having these extra sources of organic matter boost diversity and can boost activity.
Daniel Kaiser:And I'm just gonna mention one thing too. I mean, the only thing that I said the drawback on some of these these tests that measure the biological activity really is cost. I mean, haven't looked at Anna what kind of what some of this cost, but, know, you look in my realm where we're really trying to be site specific and take multiple samples from a field with, like, a grid sampling structure. I mean, I don't know if you can really afford to do it just based on some of that. So that's kind of the issue is is, you know, we're it seems to me somewhat we're stepping back.
Daniel Kaiser:I'm just kinda wondering if there's some components of some of those tests that we can maybe use more frequently or on a denser scale to look at within fields. But, I mean, that's I think that's that's kind of the problem that I see with it. It just it gets pretty expensive when you start sending these samples in.
Brad Carlson:So let's talk just a little bit about fixation. I mean, obviously, we're not applying nitrogen to our legumes, to soybeans. I go back to, again, way back when I was an undergrad, they always said, oh, well, genetic engineering holds such promise. They're going to genetically engineer corn that fixes its own nitrogen. Yeah.
Brad Carlson:Well, here we are thirty five years later.
Anna Cates:It's always right around the corner.
Brad Carlson:Well, and the point, I guess, the point that has always become clear to me is that, for instance, if you have a soybean crop out there and you give it nitrogen, it will nodulate less until you just keep putting nitrogen on. Eventually, it won't nodulate at all. It'll take what you give it because it takes plant energy. And so my point has always been with the potential of nodulating corn, Even if you could get corn to nodulate, unless it can supply its total requirement, it's not gonna make a difference because then you're gonna have some reduced yield. Or you say, well, it only supplied 90%.
Brad Carlson:Well, what it needed, it was 90% of the yield. That's, you know, 200 bushels. I'm off by 20 bushels. I need to add nitrogen. Well, once you start adding nitrogen, it's gonna nodulate less.
Brad Carlson:And so it's almost an all or none proposition if we were ever to get to that point where we could engineer that into the crowd. It's it's kind of a I don't know. It's I guess it's one of them pie in the sky things that I'm starting to think I don't think it'll ever happen. I I think they kept saying it was, you know, you just said, oh, it's always right around the corner. I don't even know this right around the corner anymore.
Brad Carlson:I I think maybe we've just walked away from that one as a as a concept.
Anna Cates:I don't know. It still makes the cover of some magazine every few years.
Brad Carlson:I suppose. So let's let's kind of finish this conversation about improved soil structure because from my point of view, this is really where everything is at because we've we've found that the better the root system of the crop is, the more efficient it is at taking up nitrogen out of the soil. It's just simply leaving less behind, and I think that maybe is the the simple the simple, easiest solution to this. I have always been impressed, and I always tell farmers to do this if they really wanna know what great soil structure is. Plan to sometime you can't necessarily always know when you're gonna have a big rain, but kinda be ready for a big rain.
Brad Carlson:You have a have a sand shovel available. Get two inches of rain. Go out on a fence line or in a woods. You got two inches of rain, start digging a hole, and you're gonna discover you can do it just fine. It's you know?
Brad Carlson:And and you know that if you take that shovel out into the middle of a field, it's just gonna be a big, clumpy, muddy mess. And so clearly, there's something to the whole concept of soil structure in some of these native systems that doesn't exist in our farm fields. And really, I think that's kind of the holy grail. If we could get soil structure in our farm fields to emulate what it's like kind in native prairie, in the woods, on a fence line, or whatever that is, boy, we could really go a long way to being efficient with our fertilizer use.
Anna Cates:Yeah. One of my friends in the SWCD down in Mower County, Steve Lawler, says that is the ultimate soil health metric is to walk in your field after a big rain. Notice where it's ponding, notice where your boots are getting muddy, notice where it's all sunk in, and that shows you just what you're talking about, like how the water gets in and how well your soil is functioning at that. But I think and I I think also it's not like you say, yes, this year's corn roots are what's driving the nutrient uptake, its ability to scavenge all the nitrogen from the soil, but you gotta think about how many roots have touched that soil over the last ten years. Right?
Anna Cates:In a prairie, I think every handful of soil is touched by dozens of roots. And in a cornfield, you've got this soil that your corn root is the first one there in a few years, and so it's not following an easy path. It's not it doesn't have those dead roots nutrients to scavenge on. It doesn't have those dead roots microbial communities to work with. It's just it's just a little stingier.
Anna Cates:It's like living in a desert instead of a tropical rainforest or something.
Brad Carlson:That that's that's an interesting way to put it. You know, I I think really what it kind of amounts to is we don't have the prescription to recreate that condition right now with our annual cropping systems. And, you know, it's it's gonna be a topic for another day when we talk a little bit about perennials, and we talk about cover crops and so forth. But, you know, as of right now, we just aren't able to recreate that type of soil structure in in our annual cropping systems.
Anna Cates:We can get pretty good if we are doing no till and have cover crops or more diverse rotation. Again, the more time roots are in the ground, it does change.
Jack Wilcox:That was Brad Carlson, Extension Educator out of Mankato. Daniel Kaiser, Nutrient Management Specialist here in Saint Paul. And also in Saint Paul, Soil Health Specialist Anna Cates. We appreciate it very much.
Brad Carlson:Thanks, Jack.
Daniel Kaiser:Thanks.
Anna Cates:Thank you.
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 their corn check off investment through Minnesota Corn.