Accounting for soil and weather conditions: Methods and tools to help fine-tune your N
Hello, you're listening to Advancing Nitrogen Smart, the podcast series from University of Minnesota Extension. I'm Jack Wilcox at the communications desk here in Extension.
Jack Wilcox:Today we're going to discuss tools to help farmers account for soil and weather conditions in their nitrogen fertilizer management. Here with me are Daniel Kaiser, nutrient management specialist with Extension, and Brad Carlson, Extension educator.
Jack Wilcox:Brad, what are some of the methods and tools farmers can use to account for soil and weather conditions?
Brad Carlson:You know, we've always talked about the fact that our recommendations are guidelines and they're places to start, that there are legitimate reasons to be varying what you do, but the way that nitrogen behaves is a science, and so the conditions where some of that changing happens are knowable conditions. And so very particularly, weather conditions are the things that we need to be kind of watching for. Obviously, there's other stuff related to past management and past experience and soil conditions, which of course then relates to the weather also. There are a number of tools that you can use for decision making that have been developed over the years. None of this stuff is real precise.
Brad Carlson:I know I had a long discussion early in my career with Doctor. John Lamb because I had used the phrase farming is an art and he kind of didn't like that. Later in my life, would suggest maybe I don't really like it either, except the thing I was kind of getting at is that it's not always possible to have complete information. So in a lot of cases, you have to kind of use the best information available and kind of go off of a, I don't know if I wanna say a hunch, but maybe educated guess is a lot better phrase for that. And so there are a number of things that have been developed over the years that that look into the those kinds of things to to modify your management.
Daniel Kaiser:We do have options. I mean, as Brad said, mean, nothing's really perfect. You know, if you break down soil and tests, the pre plant nitrate test has been around for a while. That's something that you should be taking before you apply fertilizer just because for trying to account for some of the nitrate that's there, it's better off doing that ahead of time and, you know, applying a rate that is relevant based on that test. I mean, that's one of the issues with nitrogen is when you overshoot it, I mean, these things are really gonna do you a whole lot of good.
Daniel Kaiser:But that's an option that's been around for a while. The pre side dress nitrate test is different. So the pre plant nitrate test, we recommend a two foot sampling to get more of what's in the profile relative to the pre side dress which is more of just looking at a risk assessment of whether or not you're short after fertilizer has been applied. This would be taken sometime in late May to early June to get an assessment of whether or not there's enough nitrate to carry you at least through the times when we see peak uptake. And that's one of the things about a lot of these nitrate tests, specifically the in season like the pre side dresses, you have to take it at the right time.
Daniel Kaiser:You can't just go and take a test at any point in time because if you go too late, in most cases, the nitrate that was in the soil is being, you know, drawn on heavily around, you know, v 10 to r one somewhere in that time frame for corn that if you go and take a sample around tasseling or post tasseling in the soil, you may not find a whole lot of nitrate there because the crop's taken it up.
Brad Carlson:And this is where it's really important to understand the way nitrogen behaves in the environment because that test, for one thing, it's only sampling nitrate. So we're not you mentioned, Dan, not taking the test after fertilizer has been applied. For one thing, it's not really been calibrated to account for that. Number two, sampling. The protocol for sampling after fertilizer has been applied is very difficult because if you broadcast urea, that's one thing, it's kind of spread evenly.
Brad Carlson:But if, for instance, anhydrous was knifed in, you're gonna just see a lot of variation from where the knife was to in between the knives, and that can be problematic also. But beyond that, there's just a lot of things relative to the soil nitrate test that you have to be aware of that, first of all, nitrate is subject to be lost. And so part of that is potentially leaching, so it can move down in the soil profile. And so you mentioned that we take a our pre plant recommendations are for two feet, so that's accounting for the fact that it may be deeper in the profile if there's been some water movement through the profile. I guess it should be noticed that it could be deeper than two feet.
Brad Carlson:Corn's gonna root three to four. It is possible to pick up that nitrate. Sampling that deep, though, for the average person really is difficult and we just don't envision a lot of people going out taking three foot soil samples. And so that's one of the reasons why we never really looked at that. But very similarly, if you're looking at sampling, for instance, in season, you talked about the pre side dress nitrate test, which is we don't really have full blown recommendations, but we've talked a lot about it over the years.
Brad Carlson:I mean, that's another situation where the corn may be looking, it's up and it's looking piqued. You say, well, do I have enough nitrogen? I mean, it's possible that the nitrogen is there and it's just lower in the profile and the corn hasn't grown enough to reach it. And so you gotta be careful about that also. But then there's other issues relative to is it in the nitrate form?
Brad Carlson:So again, we don't recommend taking it after fertilizer application. It's possible that the nitrogen is still in the ammonium form and you didn't pick it up at all because the test only tests nitrate. Similarly, following manure applications, some of that is in the organic form. And so while we would maybe look at fields that have a long term history of manure application as being some of the places where we would recommend taking the test. If it was a recent manure application, you really don't even really know what form the nitrogen is in to be picking it up.
Brad Carlson:And then, of course, you've got the whole issue of denitrification. If you've had wet spots, then okay, so if you sample in a wet spot and you found that you lost a lot of your nitrogen, how do you manage the whole field based on that? And so there's a lot of stuff going on with soil testing. And I didn't even mention immobilization. You know, if it's corn on corn and you got a lot of corn stalks out there, you know, it could be all tied up with the decomposition of corn stalks.
Brad Carlson:And and some of that may be released, but some of them might not be released. And it's it's just a complicated topic.
Daniel Kaiser:Yeah. So I think the short of that is the nitrogen cycle is pretty complicated. You know, a couple points in there, Brad. I mean, one of the things, you know, if you look at inorganic nitrogen, we can measure ammonium in the soil. The same extraction that's used to measure nitrate can also will also extract ammonium.
Daniel Kaiser:We don't tend to use it for anything because we don't really know exactly what it means, but I know, you know, some of the research Fabian Fernandez has done here in Minnesota. He's looked at the addition of ammonium and nitrate together and, you know, seeing whether or not they can improve some of the general prediction of nitrogen requirements. I mean, I haven't really seen anything that what I'd be worried about it. There's also questions with ammonium drying the samples whether or not you lose some of it. So that's kind of one of the the issues with it that I don't typically use it for a lot of these tests to even include it.
Daniel Kaiser:And some people like to kind of use it to see whether or not they've got a lot of fertilizer that's hanging around, but it'll never equal out the same where you can measure the same amount of ammonium to account for all the fertilizer you have. So it's not really a good test. Just know that if you're sampling, you know, soon post fertilizer application, you're likely gonna see some elevated ammonium levels in the soil just from the fertilizer carrying over. And I've looked at some of this with some of my my studies and it's been kind of amazing. I mean, we we've been doing some work looking at the sampling over time, looking at ammonium nitrate in the soil and from even like an early May application when we sampled around mid May, we don't see a whole lot left.
Daniel Kaiser:There's not really not a whole lot there. So I mean it converts pretty quick if we get situations where nitrification is is get some optimal conditions for that. The other thing Brad, I mean just talking about your deep sampling. There's a reason we recommend two feet for the pre plant test and that's because they've looked at the deeper depths and they really haven't improved anything. Although there might be some nitrate down there.
Daniel Kaiser:The general prediction or the relative ability of it to assess a potential credit hasn't been much better for a two versus, know, three foot test. So that's one of the things just to be kind of aware on that. You can take your different sampling depth certainly, you know, I wouldn't use a zero to six inch sample nitrate in that to make any sort of judgment call because it's not gonna be the over relevant. We're looking at these options right now because I think the Precidress nitrate test is the big one that, you know, would give us a way to account for weather more than the pre plant. The pre plant is more to kind of set you up for a, you know, what rate you should be applying before the crop goes in and, you know, I think the two together may not be a bad option for some circumstances If you're looking at trying to reduce rate, then come back in with a back check at some point to see if you've got enough.
Daniel Kaiser:Because that's really what we need essentially is, you know, there's some questions on the pre plant test is to have some sort of methodology to come back through to see whether or not we need to make a change.
Daniel Kaiser:Well, I think the other thing that's worth noting here is there's also a recommendation for taking pre plant, pre application nitrate test for sugar beets and that's a very different test. That actually does go down to four feet as well as the results for that are given in pounds per acre. And so, it's important, I guess, that farmers, if you're doing a nitrate test, that you're careful to be following the protocol again, if you're doing it for corn, that you're following the protocol for corn because, for one thing, the interpretation of the test when we give the numbers in parts per million is assuming some background level. So there's always kind of a background level. So, for instance, for the pre plant test, if it's six parts per million or less, we recommend no action.
Brad Carlson:We consider that the background level. However, that six parts per million does represent some level of nitrogen still in the soil. And so when you get that back, for instance, that sugar beet test in pounds per acre, you can't just credit all those pounds because there's always going to be some level that's background and that's built into our nitrogen recommendations. Again, it kind of bears repeating, know what you're doing, don't just go out and do something and then stumble into a wrong interpretation. Very similarly, sending samples out of state or using out of state recommendations, we're not being parochial in saying we do it right, they do it wrong, but what we will say is it's frequently done differently in different states.
Brad Carlson:And so if you use our protocol and then you send it out of state and you get some other state's recommendations, the recommendations may not be based on the same sampling protocol you used. And so you do need to be very careful about that stuff.
Daniel Kaiser:We wanna try to end the season with the right amount or have the optimal N rate, whatever that is within a given field because we know that there's a slight change in terms of an increase in the amount of residual nitrate in the soil post harvest up to the optimal N rates. When we get beyond that point, essentially, we can leave it pound for pound somewhere in the soil profile. And if there's nothing out there to effectively utilize it or we don't credit for it, potentially, if you've got another crop that might need nitrogen the next year, essentially, we've got just extra there that's not gonna get utilized. So that's one of the key things that we know and, you know, some people might ask, you know, looking at that optimal N rate, you know, what we have for the recommendation, you know, if we apply, you know, plus or minus from that, what do we get in general and really the gains for under application really aren't that great in terms of reducing the amount of residual nitrates. So that's kind of one of the key things that needs to be assessed here is that what we're really trying to do is try to at least maximize some of the leftovers as much as possible.
Daniel Kaiser:Particularly if you're in continuous corn, that's really gonna be the circumstance where you're gonna be looking at situations where you might get residual nitrate. So when, you know, we talk about the pre plant nitrate test, there are some certain guidelines to use for it. If you're in a situation where it's corn and it's following soybeans, it's really not a situation that we see much potential for credit unless you've got manure in the rotation then it, you know, might be something that might be okay to use to look at assessment. I mean, I've seen situations in the Southeastern Part Of Minnesota. We had one site down there that cover crops and manure, corn following soybean and we had some pretty high residual nitrates.
Daniel Kaiser:And when we ran nitrogen trials on that field, the test, the pre plant test was telling us we'd have a full end credit and the data in the field was telling us as well. Now the big issue with like the pre plant nitrate test is timing. Now there's, you know, some debate amongst some of us here at the university and when to take it. You know, fall collection in the West is is typically what's recommended if you're dealing with South Central or Southeast. Look at taking that in the spring.
Daniel Kaiser:Now, that's always kind of up for debate that fall collection because we know that there will be some change in those in the amount of nitrate from fall to spring. So if you geo reference a field area, you collect in the fall versus spring, there's more than likely that you're gonna see differences in the results. Now some of the stuff when I've assessed it, differences are there but they're not if you've got a situation where you've got a lot of credit, I think it's gonna show you that both in the fall and the spring. So that's been kind of one of the questions, you know, on that. What I kind of envision was something like the pre plant nitrate testing, some of the things we've worked on is taking the sample and putting just a lower base rate down then making adjustments with an in season application to try to maybe correct for some of the spatial variability that was in the field and that's one of the things that we've been researching.
Daniel Kaiser:I'd like to, you know, a little bit more research on it but looking at where we tried it, it had kind of mixed results with it. So that's kind of the so the big thing with even with these soil tests is while they work well for things like p and k for nitrogen, there's still a little bit of a work in progress.
Brad Carlson:Well, the other thing about the soil nitrate test, we've got our recommendations for when to do it, so we're talking, you mentioned Dan with fields with a manure history, We would also look at following a drought, we would expect unused fertilizer there. Of course, if you're rotating corn to soybeans and you've got a carryover to the soybeans, nobody's gonna bother looking for that because who cares? I mean, you're not fertilizing the soybeans. However, we have actually seen the last we did have about three dry years in a row here where we were kind of finding some credits that maybe had been carried over for a couple of years. It's something worth thinking about.
Brad Carlson:Ultimately, I guess there's nothing wrong with taking the test anywhere you want to take the test, and if you find a number, it's there. Our recommendations are primarily just related to where are you likely to find a credit. As far as wasting your time and wasting your money, we're trying to help you avoid that. But if you want to take a test anywhere you want, by all means, you're welcome to go ahead and do that. The other thing about it is, it goes back to the timing of the testing, is just realize that when nitrogen is in the nitrate form, it's subject to be lost.
Brad Carlson:And so between the time you took the test and the time the crop actually needs it or the point where you want that nitrogen out there for crop growth, if there's been conditions, soil being saturated very specifically, that could have led to either leaching or denitrification, realize that that may no longer be accurate. And so we also talk about denitrification not being real significant in the late fall and the early spring when the soil is really cold, but it's something that does need to be kind of monitored that if you've got nitrate out there and it gets really wet, it could be gone. So really, the only thing about delaying the timing of the test is to just simply move it in closer to when you need to make a final decision and remove the possibility that test was no longer accurate because the conditions kind of got out of control.
Daniel Kaiser:Well, I think I'll just leave this last thing. I get, you know, questions if you are looked at something like the pre plant nitrate test, what should we be looking at in terms of how large an area should we be sampling? I don't know if there's a right or wrong answer to that. You know, one thought of mine would be if you've got yield maps for a field, maybe look at some of the consistency of your yield areas, look how that lines up with some of your soils, then maybe zone the fields based on soils and take multiple samples like that, right? I mean, there's really not a good answer to it, you know, some of the consultants if you're taking zero to six inch samples will take a six to 24 along with that.
Daniel Kaiser:So then you get a full two foot, you know, for nitrate, but then you get your upper, your p k, pH and those types of things in your surface soil. So there's some things there that to kind of think about with the soil testing, but I don't think this is right or wrong answer in terms of what you want to do.
Brad Carlson:Let's talk a little bit about tissue testing. Know this has been really popular. It was much well, for a while, it was quite popular in industry. There were particularly a few conglomerates of input providers that were kind of higher on it than others. Dan, you worked with that quite a bit.
Brad Carlson:We've never the University of Minnesota has never come out with any real recommendations on conducting tissue testing for nitrogen. I know some of the stuff I've heard over the years, there's a lot of variability from one hybrid to the next and so forth. What's been your experience with that in season tissue testing?
Daniel Kaiser:Well, problem with the in season tests that I found is, I mean, I think number one, Brad, you brought it up. It's the hybrid aspect of it. There's some variation among the hybrids and some of that might just be, you know, due to differences in maturity at point. If you're sampling at the same time, I've done this before where we sampled multiple hybrids in the same field which are part of the variety of the hybrid trials for the university and you'll get different results. So that, you know, kind of begs the question of whether or not you have a separate optimal nitrogen concentration for all hybrids.
Daniel Kaiser:How you'd ever determine that, I don't know because the hybrids come and go in the market so quickly that by the time you get a good dataset, I'm not sure it would be overly valid. The issue with nitrogen, you know, particularly nitrate, you know, if corn is a good example of this but for some other crops like sugar beet and potatoes where you have petioles on you know, leaflets connected to a petioles to the stem. A lot of times petioles are looked at as a way to measure nitrate availability because the amount of nitrate in a petioles, the petioles in a storage structure, it's more nitrates more transient in there, sort of moves through there that that might be an indicator of general availability at a given point in time. The problem with it being transient, what I've seen so many times is it seems like the concentrations and this I think could go just to the total end concentration in corn leaves is that it's highly dependent more on the environmental conditions that plants growing in around the point in time you sample more than anything else. Certainly, if you have low nitrogen, you take a leaf sample, you're gonna probably find low nitrogen in the plant but it's not a given and it's difficult.
Daniel Kaiser:I think everybody kinda liked that and some people are using this as a way to look at high yield situations to track everything and the databases behind is you have to have a good database that correlates the concentration to some sort of deficit and yield. If you don't have that, you're gonna have some issues. I mean, the one of the better tests has been the basal stock test which you collect I think it's about 12 inches of stock about 15 inches off the ground. I think roughly I may have that wrong but measure the nitrate concentration in the stock and what it does is do again just gives you a general report card of that season on where you're at in terms of your management and whether you're adequate or, you know, marginal or excessive. The issue with anything like that though is we're taking that at the end of the season.
Daniel Kaiser:So doesn't really give you a good idea on how to manage for that season where the sample was taken. If you've got enough of those samples though, you could start making some judgments on your overall nitrogen management. If you are in that excessive category that you're likely over applying and could dial back. So there's some things that can be done with it. I not sure that most growers that are taking it.
Daniel Kaiser:I know it was part of some of the NRCS programs that they could farmers could take these things that they're actually using them that they were just getting the data just to get the money for their program and not really utilizing it. But there are there are some things to look at. It just they aren't perfect and that's kind of the thing with tissue testing. It it it's like anything that when you start looking at it, it's more reactionary in season. And, I mean, outside of, you know, if you applied too little, if you had an issue where you lost a lot, I mean, there'd be a situation that maybe it could help you.
Daniel Kaiser:But if you've over applied or have excessive amounts and it's really high, it's really not gonna give you anything. And one thing about nitrogen is it is taken up in the plant in excess quantities. So you have to be careful on what database you use for determining the overall availability of nitrogen because if somebody just over applies n and collects a bunch of data and gives an average of what they deem to be an acceptable value just based on just an average number of population statistics, it can be a little inflated just because of luxury uptake of nitrogen in the plant. So there's a lot of issues to kinda go by with tissue testing that it isn't, you know, for me, the initial management strategy that we're using to try to manage nitrogen in season.
Brad Carlson:Yeah. I've never personally, I've never actually collected the samples. I've looked at a lot of the data before. Everybody complains about what a horrible process it is to be going out in the field and we're looking at just prior to black layer. Right, Dan? And that kinda when they they wanna time that?
Daniel Kaiser:The basal stocks, yeah. Yes. So you're taking it right at around black layer. I mean, with the in season testing, you know, some people like to go real early. The problem is though, you have to look at your nitrogen uptake by the crop and it's so little until you get to maybe V 10 or later that most of the time the soil should have sufficient nitrogen that you're probably not gonna find much of a problem especially with anything before V five with nitrogen if you're taking whole plant samples.
Daniel Kaiser:Think it's a waste of time to go and look at it because you need to be looking at and it's really where the plants start visually showing deficiencies are at those points in time where you get rapid uptake of nitrogen mid to late season and then it's kind of a question like we see with drone or aerial imagery is, you know, are we too late at that point if, you know, we've caused a problem that we can't correct for and we've already lost yield. So it's, you know, one of those things that there's a lot more risks I think associated with that are, you know, really outweigh the benefits of it to look at managing, you know, maybe we develop something, you know, in set some point in the future, but, you know, when you look at tissue testing, there's been work on that probably back into the fifties or sixties and we're still not recommending it. So there's, you know, some people claim if you read some articles that they've found the secret of it, but I would just be a little aware wary of some of that stuff because usually they've got their own little expensive program that goes along with those numbers that you're pulling with those systems.
Daniel Kaiser:So it comes at an additional cost and the benefit to me is just not there.
Brad Carlson:Well, another aspect of this is, as I mentioned, being difficult to collect. Most farmers are not in a situation to be able to handle and deal with the samples. As far as they do need to be dried, before they can be analyzed, they need to be ground. And so that kind of turns into this, who's doing that and where is it happening? We, of course, have research facilities where we have plant dryers and we have plant grinders and we can do all that.
Brad Carlson:In your typical commercial ag situation, that may not always be completely known as far as how that would get taken care of. The other thing about that basal stalk nitrate test, again, that gets into work, we're cutting cornstalk. I mean, that's not an easy thing to do. Like our researchers, I think the field crew here developed an electric shears they were using to cut those or something of that sort after experimenting with all sorts of things from machetes to branch trimmers for trees and so forth. This is not a simple thing to do.
Brad Carlson:I know that NRCS was pushing it at one time, it's still in there. We did some work with them and they said, Well, still in there, we don't see a lot. I think probably the key is if you've been adjusting your nitrogen rates and you do have some concerns, did I under fertilize, did I over fertilize, you can interpret the basal stalk nitrate test to give you an indication if the plant was really short on nitrogen or if nitrogen was in excess. It can actually help you adjust your rates going forward. After that, though, like you said, Dan, it's really just not calibrated in the middle to know, boy, I really hit that head on because the plant is gonna take up nitrogen it didn't need.
Brad Carlson:And so it's not ever really clear what that exact right point was. Another area that's, I guess, worth at least mentioning, even though there's not a lot that most farmers can do about it, the modeling aspect. There were a lot of products on the marketplace maybe a decade or so ago. We're talking stuff like Encirca or FieldView, FieldScript, some of that kind of stuff that was giving in season advice. A lot of those products that we worked with, we were doing, I personally was involved in a number of different research projects on those, looked kind of good and promising.
Brad Carlson:Most of those have disappeared from the marketplace. Anytime something disappears from the marketplace, the first thing you have to think of is, you know, ultimately is the company that was putting them out there wasn't making any money on it because typically things, even if they don't work, they they stay put if you're making money on them. That's just the way the world works. However, you know, when we talk about did they work or not, ultimately, what you have to go back to is what's your definition of working because they were intended to make a nitrogen rate recommendation. They were not intended to increase yield.
Brad Carlson:I think a lot of farmers thought they were gonna find a lot of underperforming spots in their fields with these nitrogen models. And in reality, it was telling them that they were probably already fertilizing adequately in most places and in a lot of situations, reduce the amount of fertilizer. So the extent to which they gave an accurate nitrogen recommendation, they did work. But a lot of farmers said they didn't work because, well, they didn't improve yield and they didn't improve profitability, and that's maybe not technically accurate. Ultimately, you have to recognize that if it's telling you to put on less fertilizer, you're never gonna see an increase in yield.
Brad Carlson:It's just simply a situation of where if it tells you to put on less and your yield stayed the same, well, it was an accurate recommendation. The ability to make a big profit off of that by lowering your N rate by 20 pounds or 30 pounds just wasn't real significant. All those things kinda had a cost per acre. And when you looked at lowering your in rate by 20 pounds, it kinda was a wash when it came down to, did you save enough money? And so a lot of farmers experimented with those things and then they just kinda disappeared.
Brad Carlson:Because they did show promise that we were we were kinda finding that the recommendations they were giving were accurate, that we were able to, in a lot of cases, reduce nitrogen rate and achieve the same yield with kind of what the farmer was doing previously. I do think in the long run, these things are gonna be coming back because of some of the environmental stuff. And I would also suspect that some of the great advances in the last couple of years in AI, there may be some different aspects to them than there was in the past. But I do think crop modeling, while there's almost nothing on the marketplace right now a farmer can use, it's something at least worth talking about.
Daniel Kaiser:The main issue really, I think, on the modeling side is how much certainty growers have if they do reduce their rate that they'll get these optimal yield. And I think that's the big thing that I see with a lot of this is this the overall fear that when you start talking about reducing rates that you're gonna be undercutting yield so much that there's really no guarantee for these growers even financially if they lose yield that it when you get a cut undercut profitability like that, you're just just concerned about your overall profitability of your entire enterprise. So I think that's the main thing, you know, with these models, how comfortable growers are gonna be with it telling them they need less.
Brad Carlson:I know. Well, but but on the same token, Dan, though, it's, you know, if if you're under pressure to apply less, the model at least gives you some backup that, you know, this is looking at it scientifically to at least, you know, versus just shooting from the hip and putting on less, it it is actually a tool that can help reassure you it's okay.
Daniel Kaiser:And I'm not saying it's bad. It's just to me, I think that's the the main issue with it. If you start looking at from a growers perspective, you know, because we get that a lot of times even with the MR 10, they look at that number and like, oh, you know, that just doesn't seem like enough for I've got two fifty bushel yield and that just, you know, 50 pounds of corn following soybeans just isn't gonna be enough for my field because factor that, I mean, we're still have an industry that really ingrained these factors in that equate the pounds of N per bushel produced and the issue with that is is we know that there isn't always a clear linkage between those two things especially with the older numbers. I mean, still, I can't believe some people still use 1.2 because if you look at those numbers, I mean, you're gonna be putting a lot of nitrogen on and if that's there, there's, you know, and not utilized, that's a lot of nitrate that's, you know, potentially gonna be lost to the tile lines after that corn crop comes out the field. So I think that's the big thing is, you know, getting growers to use these things and see because you've got I think one good example with the study you worked on with an on farm trial where it was continuous corn and they had 250 bushel plus yield and it was telling them, you know, what for corn and corn about 150?
Brad Carlson:In fact, one of those strips yielded two seventy seven where they only put a 50 on.
Daniel Kaiser:So we know those circumstances are out there. It's the big thing about these things like models is the fact though that maybe they can help us make the decision upfront because that's really the big problem is once we get the fertilizer applied, it's too late. I mean, we can't adjust it back. There's no way to take it back out. It's not like P and K where if it's not utilized, it might be back the next year.
Daniel Kaiser:I mean, once it's nitrate, there's a pretty significant risk it's gone. So in the past, I mean, really the only way we've been able to do that, we had the supplemental and worksheet that was developed before my time. That's more of just a qualitative assessment of whether or not there's enough loss to potentially consider applying supplemental in. You know, most people anymore since we have the ability for variable rate, they really want some rate recommendations based on the data but like something like the supplemental and worksheet just really says about 30 to 50 pounds, you know, 30 pounds corn soybean or, you know, 40 to 50 for corn following corn. Should you be in a situation if you when you sum up everything that's in that worksheet that we consider enough loss for supplemental and application.
Daniel Kaiser:So that's kind of the big thing with it, any of these things. It's that step further in terms of what to apply really becomes kind of the issue because I think all these things models or, you know, some of these things like the supplemental and worksheet do some really good job at least of giving us an idea whether there's a high probability for loss. It's that next step of then how much do you apply is really the bigger question.
Brad Carlson:Well, and I think there's also this distinction of, you know, what is your overall rate you're trying to apply versus, for instance, the supplemental and worksheet is also a tool for rescue treatments. And so some of this stuff is used after we thought we did our best job and now we had conditions where we know we lost a lot of nitrogen, and now we're trying to figure out, do I need to come back and add a little bit more? You know, and so so, yeah, I mean, the the the thing that I think a lot of people don't like about the supplemental end worksheet is when you get done, it doesn't really tell you what specifically to do. It gives you an idea if you're likely to have a problem with the overall amount of nitrogen in the crop. But it does get back to some of that timing and what can you actually reasonably achieve with a rescue treatment.
Brad Carlson:Because this past year in 2024, we had those incredible rains in June and there was a lot of fields that really looked nitrogen efficient. I know that there's a research project kinda ad hoc. Jeff Vetch did some rescue treatment trials at Waseca at the research station there and some corn that looked really bad in June. And I think he supplemented 40 pounds of nitrogen, he got a 15 bushel yield increase, which, of course, paid for the rescue treatment. However, the corn still ended up overall where there was no rescue treatment applied, still ended up yielding two ten bushels an acre.
Brad Carlson:And so it does point out there's a lot of farmers who were saying, oh, we lost all of our nitrogen. We gotta put it all back on. Well, that wouldn't have made a big difference. I mean, clearly, even though the corn looked terribly nitrogen deficient out there, the fact that it was able to yield 210 bushels an acre means, a, you didn't lose it all, and b, we've also got to account for the fact that we mineralized a whole lot of nitrogen out of our soils. And so provided the weather straightens out, you're gonna get that, and I guess the point I like to make is if the weather didn't straighten out, you can't fertilize your way out of bad weather.
Brad Carlson:And from that standpoint, it really wouldn't have made a lot of difference to just simply have applied a large amount of nitrogen. So that worksheet, I do think, is a useful tool for people who are kind of scratching their heads saying, Where am I at with things?
Jack Wilcox:Daniel Kaiser, Extension Nutrient Management Specialist, and Brad Carlson, Extension Educator, thank you very much as always.
Daniel Kaiser:Thank you.
Brad Carlson:Thanks.
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 checkoff investment through Minnesota Corn.
