Nitrates & placement: Factors for reducing nitrogen loss to water
Hello and welcome back to Advancing Nitrogen Smart, the special podcast series from University of Minnesota Extension. I'm Jack Wilcox in Extension Communications.
Jack Wilcox:Today I'm here with Brad Carlson, Extension Educator in Mankato, and Daniel Kaiser, Nutrient Management Specialist with Extension out of St. Paul.
Jack Wilcox:Environmental issues and nitrates continue to be top of mind here in Minnesota. Today, we'll discuss nitrate management and placement as factors to be aware of. Dan, start us off with some of the basics when it comes to reducing nitrogen loss to water.
Daniel Kaiser:So, you know, when it comes to reducing nit I mean, nitrogen loss to waters, I mean, really, there's one main thing to remember, you know, particularly as it relates to our fertilizers. The fact that if you look at the form of nitrogen, that really dictates the overall loss potential because the bulk of what we lose is in the nitrate form. So fertilizers themselves, the bulk of what we apply is in the ammonium form. Ammonia, n h three is a gas. N h four is ammonium, which is the ion that's held in the soil.
Daniel Kaiser:And with our soils, they do have the capacity to hold ammonium where if most of our fertilizer is in that form, the risk for loss is relatively low. So or it's well, it's almost nonexistent really for most of our high clay soils. The exception would be some of our sandier soils, which don't have the ability, which we could leach it. But, for the most part, that's I think one of the main questions we get particularly late fall later fall applications from growers. We get rainfall in in December is is one of the bigger questions is did I lose anything?
Daniel Kaiser:And really, the thing to remember here is that ammonium is stable and is held. So it's it's nitrate, again, is the bigger problem.
Brad Carlson:Yeah. And I I think it's just some basic soil science. If you look at clay particles, they actually you can think of them as like a sheet, like one solid sheet that got shattered into billions of tiny little pieces. And so everywhere where one of those edges are, created negative charges. That's just the way the chemical bonds were.
Brad Carlson:And so the the fact that the that ammonium is positively charged, it it will stick to, absorb magnetically, basically, electrically, to soil particles. You know, when we get over to nitrate, which is negatively charged, it's really not so much of a fact that it it doesn't really repel, but it's not held anymore, and so then it's just free in the soil.
Daniel Kaiser:And really what's important here is when we're talking about is leaching. I mean, at some later time, we'll likely talk about the potential for runoff losses. I mean, really, for nitrogen fertilizers, that really isn't as much of an issue unless you have a situation where you've got fertilizer applied to some sort of surface that the water that's dissolving the fertilizer can't penetrate. So that's really the main issue with it that with it is we're mainly talking about leaching. And with fertilizers, I mean, again, the source is ammonium, anhydrous, urea.
Daniel Kaiser:I mean, urea itself is neutral. If you look at the molecule, it's actually a, organic molecule that has to be converted first into ammonia, then ammonium, then further then we get nitrification occurring that moves that over to nitrate. Other sources, MAP, DAP, AMS, ammonium phosphate, diammonium phosphate, ammonium sulfate, sulfate. Those are all ammonium sources or n h four, not n h three. You know, some other older products, ammonium nitrate used to be around, not as much anymore, although there's some derivatives that are like ammonium nitrate sulfate or calcium ammonium nitrate.
Daniel Kaiser:There's some different versions of it that they've tried to use to stabilize it. It just isn't anything that's in the market. The other source, I mean, UAN, it's 28 or 32%. That's urea ammonium nitrate. So there is some nitrate in in UAN.
Daniel Kaiser:That's why on the terms of timing, fall application just isn't a good option because you can't stabilize nitrate with that. So, you know, we wanna be careful with that. And then a manure, lot of manure, it's it's split between two. It's split between, inorganic or it's might be inorganic nitrogen mostly in the ammonia form. You don't find nitrate in manure, really.
Daniel Kaiser:I mean, there might be a small amount, but it's very minuscule compared to the ammonia. And, also, manure really total nitrogen, organic nitrogen are really two main sources with that.
Brad Carlson:And and both between the excrement from the animal, then also the bedding is a big part of that, you know, particularly when we get into to cattle. How they're bedded is gonna be a big factor in that. And so, you know, especially, you got dairy cattle if if they're bedded with with straw, which doesn't happen so much anymore, but sawdust, of course, is a carbon source, and those are gonna be factors. But then also, if you got beef cattle frequently bettered with corn stalks and stuff like that, it's really going to affect what percentage of that is in the organic form.
Daniel Kaiser:And, you know, again, looking at there are some sources of nitrogen fertilizer that are in the nitrate form. So again, UAN has a 25% of the total n you're applying is in the nitrate form. I mean, the main thing to remember there is you can't stabilize that. So that really begs a little bit when you start talking about decisions on timing that, you know, if it's in the nitrate form, it's it's potentially there for loss. So UAN works well, particularly for applications post planting because of that nitrate.
Daniel Kaiser:It's mobile. It'll get down to the roots relatively quickly. But if it's out there for too long before there's a plant to take it up, it becomes more of an issue. So it's just one of the things, you know, with most of our fertilizers we apply, you know, again, most of them will be in forums that initially shouldn't be leached. It's just gonna take processes like nitrification that come into play, which will convert the ammonium over to nitrate where then we start seeing some of the issues.
Brad Carlson:Yeah. I you know, we we talk a lot at Nitrogen Smart that that the loss process of nitrogen are kinda contingent on a couple of things that, first of all, most of our loss is happening at the point where nitrogen becomes nitrate, and so predicting the percentage of nitrogen that is in the nitrate form is important. And then after that, they're they're water based, either leaching because of water percolating through the surface or denitrification up in the air. But both of those processes happen when the nitrogen is in nitrate, and so the extent to which it's been converted is is very important in that equation.
Daniel Kaiser:And with nitrification, one of the things that we do know that there is some effect that temperature has on it. I mean, that's why when we start talking about later fall applications, 50 degrees comes into play. Because if you look at the accumulation of nitrate, it slows, substantially once we hit about 50. And once you get above 50, then it'll start to ramp up. You know, it tends to be somewhat of a linear increase for the increase or direct increase in nitrification for an, you know, increase in in temperature.
Daniel Kaiser:But also other factors like pH can impact, nitrification. That's mainly because of the effects that that, soil pH can have on the nitrifying bacteria. And in particular, you know, it does have an impact on how they recover. If you put a band of anhydrous ammonia in the soil where we get the sterilization in the zone, that lower pH soils will have a slower recovery. So you'll get a longer period where you should see a delay in in nitrification occurring.
Daniel Kaiser:I mean, there's been some data on this, out of Illinois that I've seen where, you know, you look at nitrate accumulation per week. They looked at a higher application rate of 360 pounds of of nitrogen. Where at, you know, 45 degrees, they were seeing roughly about 20 pounds of N accumulating per week for a neutral to basic soils or high p neutral to high pH soil. When you get to 80 degrees, about a 180 pounds of of nitrate accumulating after a week of nitrification. So you can kinda see, you know, we look at Minnesota soils.
Daniel Kaiser:We get into late May, early June, soil temps start to increase that, it doesn't take a whole long time for for soils if they're more in that that neutral kind of that pH around six to seven, seeing those, nitrate accumulate in those soils. You know, they've had some examples. It was interesting comparing a lower pH soil at around five, and they saw about only about a third of the the accumulation of nitrate versus that the neutral soil. So, I mean, take a while for it to get there.
Brad Carlson:Yeah. It does take a while, but it's also important to realize that there is a time component to that and that so so for instance, and this this isn't really a lot of what we're gonna cover today, but when we did our work looking at climate stuff, you know, what what I kinda found on average looking at the temperature averages is is depending on exactly what your timing was for application. But, like, with the fall application, we get on average about six weeks, and, you know, it could be as short as three or four. But, typically, there is six weeks between the time the temperature gets down to 50 and then when it freezes. And then again, when it thaws out in the spring, you know, you've got another chunk of time in there.
Brad Carlson:The the soil temperature's cold. The rates of conversion are slow, but you're talking about twelve, fourteen, sixteen weeks, and so that that can add up.
Daniel Kaiser:Yeah. And that's mean, it's just some experience here in Minnesota. I mean, we do a a number of studies that we sample in season after fertilizer application. And, you know, just kinda recently, we've been doing some work sampling, and we'll take samples in May before we put fertilizer down and sample in June about a month later or so after the fertilizer is applied. And, you know, the sites, you know, about half of them, we can still detect some ammonium in the soil from that that, preplant urea application.
Daniel Kaiser:And about another half, essentially, it's it's all over to the nitrate form by the June. So that's one of the things about it. There I mean, again, it's depending on temperature and, the general from what I see, you know, we look at within a couple weeks, it's, you know, looking at the rates we're applying. We could pretty much expect the bulk of the nitrate, you know, particularly we start getting to warmer soil conditions to be convert or ammonia to be converted to nitrate from a spring application.
Brad Carlson:So one of the concepts that's talked about frequently is nitrogen use efficiency, which is is how much of the applied nitrogen is ending up in the plant. But also, there's a kind of the the inverse of that, which is how much of it's actually being lost also, Dan. I know you you kinda looked at that with with from an environmental perspective with with fertilizer applications.
Daniel Kaiser:Yeah. And there's we expect some losses. I mean, you're gonna get some, particularly with denitrification, because if you look at soils, I mean, while we have some soils that are well drained, there'll be pockets in that soil that can be saturated for a longer period of time, maybe that have smaller pores where you see a small amount of denitrification. We know that you just talked about nitrogen use efficiency that, you know, roughly, you know, anywhere from 40 to I mean, some people say up to 70% of the end that we apply is taken up by the plant. Normally, here in Minnesota, the numbers I have are, you know, 40 to 50% that we're taking up.
Daniel Kaiser:And that doesn't mean that that additional 50% is flushed out to the tile lines, because we know that, you know, if only 40 to 50% of of what we the corn needs is being or that we're applying is being taken up by the crop, there's still a substantial amount more of nitrogen that has to be taken up by the crop from other sources, which is generally mineralization through organic matter, residual nitrate, maybe some other sources, atmospheric deposition, fairly small in the grand scheme of things. But, you know, some of that that additional nitrogen that's not being utilized in our fertilizers is likely also going into replacing some of that nitrogen that's being mineralized with organic matter. So we're seeing it being utilized in the decomposition of residue. It gets incorporated into microbes. And then future years, when we get mineralization, some of what we apply this year may be coming out in through some of the mineral the future mineralization.
Daniel Kaiser:So it's not that it's necessarily lost. That's one of the things the misnomers about nitrogen use efficiency is that, you know, some of that nitrogen is just being basically recycled back into some of these processes that annually supply our crops. So...
Brad Carlson:Well, and a lot's been a lot's been made about the fact you get a a corn crop that's yielding 250, 270 bushels an acre. You know? The guy will say, woah. All that residue there is, but it's also reaching an equilibrium breakdown because, you know, if it wasn't, it'd be three feet deep out in the fields right now. So we know that that stuff is breaking down.
Brad Carlson:It's getting back into the organic fraction. The more there is, the, you know, the the more is that is gonna happen because like I said, it's not accumulating over a long period of time. I mean, we're not getting this duff layer in fields like you get out in the in the forest or something like that. And and and, you know, I think I think it's also kind of thinking out loud here, but I think it also sorts of sort of begs the question too as we start looking at shorter stature corn that maybe doesn't have quite as much vegetation on it. You know, it'll be interesting to see how that dynamic plays out a little bit too.
Daniel Kaiser:Well, then if you're planting it more densely I mean, so if I it's if say the uptake's 10% less, but I I plant 10% more, the total biomass is about the same, then it really doesn't matter in terms of overall uptake. But, I mean, the main thing we're dealing with when it comes to loss is that loss is a percentage of the total that we apply. I mean, so, I mean, if you look at loss from spring to fall, we can't think that, you know, we're just gonna lose 10 pounds. You know, we've we're probably gonna lose month something more like 10 you know, just throwing a number out there, 20% or something. So it's a percentage of the total.
Daniel Kaiser:So the more we apply, the more total pounds technically put at risk for loss. So that's one of the issues with it, when it comes to planning, you know, when we start talking about nitrogen fertilizer application rates. Why? One, I don't really like using last I mean, if we've had a year where a field needed more nitrogen just then automatically applying that the next year because if there's adverse conditions that were impacting that, it doesn't mean that that's gonna occur the next year. And if we're losing a large potential of that nitrogen, then the more we apply, the more total pounds potentially that could be leaving the field.
Daniel Kaiser:So that's really the the issue with it. You know, we look at Minnesota. It's one of the challenges is coming up with the nitrogen fertilizer guidelines is that, we have a lot of diversity in our soils, climatic conditions that can affect nitrogen requirement. So, you know, there's no one size fits all approach that may work across all farms. What I have to do though with the nitrogen fertilizer guidelines is try to at least give us a reasonable starting point where we're not just grossly over applying because if the plant can't take up the nitrogen that's out there, it's gonna be left.
Daniel Kaiser:So starting with too high of a rate really becomes really a major issue when it comes down to loss because then, you know, looking at if there's if we get the condition that certain conditions exist, and I know, Brad, you've seen this before in some fields where there's been situations where it's almost like all of the nitrogen that was applied has has disappeared. There's been years like that that we've seen that. So, you know, looking at the farther out we put that ahead of the crops going in, that's I think the real thing that needs to be discussed right now is we should be looking at do looking at more split style approaches where we put less nitrogen at risk upfront and do and, concentrate more nitrogen in season. I mean, it could it's just a good a good kinda discussion point, really with that's unpredictable some of our our rainfall patterns have been the last few years.
Brad Carlson:Well and and, you know, and, again, the other side of that coin is is we've we've we've got mountains of data that show that when we overapply that if we and I'm using that term loosely, but, I mean, basically, study, you go back, you look at what the MRTN was in that field, you'll find residual soil nitrate that's almost pound for pound what the extra applied nitrogen was. And so, you know, then the question starts becoming, are we able to be prescriptive enough to find that ahead of time and not always in reverse? Sort of sort of off mic here. We've had a lot of conversations this morning about AI, and and, you know, we looked at the potential that maybe crop models might be able to predict some of that, and and indeed, we were kinda finding that maybe they were both between a factor of driving off of Sowell's maps and then yield maps together, kind of identifying what was going on. But I think, you know, AI may also short circuit that process.
Brad Carlson:In the long run, we might be able to we might be able to identify sites in the field that are more prone to nitrogen loss as well as those where we're maybe not getting as much of a supply from the soil organic matter.
Daniel Kaiser:Yeah. That's one of the issues with corn too, and one of the main problems is the fact that since it's not negatively impacted by over application, it really no simple way to tell us whether we've over applied. I mean, there's certain tools out there that we can use. I mean, they kinda give us a report card at the end of the season, but at the end of the season. So it'd be nice to be able to make some of these decisions upfront.
Daniel Kaiser:So, I mean, moving forward, I mean, if that does become an issue with having more weather variability and especially precipitation that, you know, it's kinda what I said before is that decision to apply less upfront, and then when we start knowing what the season's gonna look like more and have better prediction of the the forecast as we go through, maybe we can do a better job of trying to manage for some of these extreme environmental conditions and have less risk. It's really nitrogen management. A lot of the decisions really boil down the risk management. Logistics have been coming into play, and that's really mainly on the retailers and what they can supply. That's, I mean, really more of my concern right now versus rate because we know that there's more instances where we see problems with, if you look at the four r's interactions between source and timing just because of some of the things we talked about before in the conversion of the the fertilizer we apply into the plant available forms.
Daniel Kaiser:So that's kind of the the main issue with it right now is it's it's not simple because there's a lot of interacting factors that need to come into play, and, you know, logistically right now is my main concern.
Daniel Kaiser:I think the easiest thing to control would be having different sources available to growers, but we see less and less of that, particularly with anhydrous ammonia in areas where anhydrous ammonia would be better particularly for fall application.
Brad Carlson:Right. And and so, you know, going I guess, going back to our environmental standpoint here, when we start talking about, you know, what our big concern is with this, which is loss to the water, you know, we've been focusing on the conversion to nitrate. I think it's important to recognize that another portion of that is, you know, that we're really concerned about the total flux. And so that's a factor of both concentration and the total amount of flow.
Brad Carlson:It's not really a topic for today. However, we do need to recognize that that one of the the sets of edge of field practices that's applicable to this is reducing the amount of flow. And so, you know, in Minnesota, our watershed plans that we got are starting to address water storage on the landscape. Some of that may involve controlled drainage, which is just simply reducing the amount of water flowing through drainage systems. Some of that will play a factor.
Brad Carlson:I think it's also worth recognizing, though, that if we're retaining water in the soil profile, we may also be saturating, and we may be denitrifying it too. So that could add a little wrinkle here, but but at least our data is kinda showing that we don't see a lot of difference in the the nitrate concentration when we use that technology. We're primarily just just messing with the flow.
Daniel Kaiser:And really to go back to this, I mean, you look at nitrate concentrations when it comes down to it. I mean, we could be well below 10 part per million in many cases coming out of the tile line, but the more water coming through, the more total pounds that are being lost. And that's kind of the issue. Think, Brad, what you're getting at there is is the what's what we're the limiting factor and why it concerns me some of the loss targets that we have, how well we can achieve them because we know that there's gonna be a certain amount of end loss just because of the annual cropping system. We just know that happens.
Daniel Kaiser:And we can do everything we want we we can to limit the the concentration coming out of the tile line as as low as possible. But the problem is mother nature gives you a ten, fifteen extra inches of rain in a year. You get more tile flow, and then the the total the total load coming through increases. So that's kind of the problem right now that we're dealing with, with it is these some of these management scenarios, we just kinda upfront have to give growers the the idea what are the best practices. That's why we have the BMPs in place, but then we're just relying on mother nature then to, see what get throw gets thrown at us in a particular year.
Brad Carlson:And and I think it's worth again noting as we talk about where what we're trying to achieve that Minnesota's nutrient reduction strategy that has broken the state down into its HUC eight watersheds, the watersheds that are roughly one or two counties in size, has really two different maps. One is the total load that they want to reduce the nitrogen going through those rivers by, but the other one is looking at the percentage of reduction that that while you see a large you know, the the the majority of the watersheds that have the highest total amount of nitrogen reductions necessary are in the southern third of the state. However, the ones that have the highest percentages are on the western side of the state. And so that's also adding a dynamic in this that that, you know, some some of this is also relative to to the amount of flow. It it gets into a lot of nuance as far as from a management standpoint, how we're going to actually affect that, but I think it is worth at least people understanding that that's kinda what's going on.
Daniel Kaiser:Well, that's one of the things looking at just from a management standpoint, and that's kinda why we stress is what the information that we provide, and isn't that it's gonna be work for everybody across every acre in the state. So that's why you've really takes to kind of look at evaluating your particular situation, your soil specifically, are the main thing. That's one of the the biggest things on our b nitrogen best management practices is they're meant to be soil specific, not necessarily county specific. Even though if you look at the publications, we've got nice color coded areas that represent mean, the Southeast is a good one to kinda target because there's soils that overlap the those borderlines than areas that would be in the South Central BNP region. So you just have to kinda know what the soils are at and know what the issues are to make sure that you're really putting, the nitrogen at the lowest risk for loss.
Daniel Kaiser:And, you know, it's always to realize the fact that all the time everybody focuses on rate, rate, rate, and rate, and there's other things that come into play, I think, me, that can cause more issues than just with rate.
Brad Carlson:Right. And so we're kind of working off of your curriculum, the curriculum we developed on reducing nitrate lost water. And and in this particular one, Dan, you were the one that put this piece together, which was looking at the four r's. And, you know, we keep stressing the fact that that rate is only one of the four r's, and it's bound by other aspects first. And so, you know, for this this we'll be covering, and we already have covered some of those other four r's in different podcasts. So for the sake of our podcast here today, the one area I wanna focus on here for the rest of the time is talking about placement.
Daniel Kaiser:Yeah. And with placement, I mean, looking at it, we know it is gonna have really very little effect on nitrate loss, mainly because nitrate is water soluble. So whether it's on the soil surface or whether it's below the surface, I mean, really, there isn't a whole lot of difference there. I mean, we know that I think you look at a silt clay loam soils that with an inch of drainage, I mean, nitrate will move about six inches. So, you know, obviously, if you have it deeper in the profile when it's applied and there's less time that it would take potentially get to tile line, although I don't really think that really occurs all that much in most years.
Daniel Kaiser:I mean, there's situations where you get enough drainage where it might move it in some of those, but but really placement is ammonia volatility. I mean, it's a loss pathway. It's not necessarily an environmental issue, but in terms of-
Brad Carlson:Well, my it might be from a climate standpoint, but that's not really our focus right now.
Daniel Kaiser:No. Ammonia. I mean, there's ammonia in the atmosphere. So, I mean, it it's not as big of, I think, an issue at this point. You know, really, the bigger issue would be runoff.
Daniel Kaiser:And that's kinda where placement comes into play because tillage, I mean, looking at a BMP, I mean, we know that can be a BMP for phosphorus when it comes to runoff because getting the the material incorporated with the soil greatly reduces the amount of potential loss. And with nitrogen, it's the same thing, particularly if you've got a sloping ground or you're applying frozen ground is the worst. I mean, that's one of the ones I would avoid at all possible, particularly nitrogen fertilizer because it's so water soluble. So it didn't take a whole lot of water running off the field to dissolve and carry, urea itself. I mean, urea will move, and it moves out.
Daniel Kaiser:And if it can get into water bodies, then it can eventually convert to ammonia and then potentially denitrate. So there's some risk there with it, or essentially, it's gonna sit there as total nitrogen. So, I mean, looking at the data, if you look at fertilizers, I mean, initial rain events, immediately after application are the worst risk for loss. Generally, if you can leave it long enough on the surface where it can dissolve, maybe get a few smaller rainfall events where the water can move down into the profile, then that some of that, that when we see that that urea hydrolysis, which is the initial conversion of urea to ammonia than ammonium, once that starts to occur, then this then it should be held as long as we don't see the runoff causing erosion, and that's the other thing. So if you look at just just a couple examples here, some work looking at poultry litter, I mean, it's it's pretty apparent.
Daniel Kaiser:You look at incorporation versus not incorporation, what exactly can be done with a significant reduction. That's what I did in the past in Iowa State. We looked at phosphorus, but also another researcher looking at, nitrogen, and it was pretty clear if you can get the material incorporated, it could significantly reduce the potential for loss. So that's the worst case scenario is frozen ground. I mean, Brad, we get people will talk about this.
Daniel Kaiser:I mean, you get towards the late in the season. I mean, if it's been wet, it ground starts to freeze. So, you know, ideally, people like to get out there and not cause compaction with some of these floaters. So you start talking about applications on top of frozen ground, and they're just a lot of risk.
Brad Carlson:Yeah. That I mean, that's that's a risk for MAP and DAP, but then you get you will will also get particularly, you get a fall that was not conducive to getting fall in on like you normally would if it froze early, if it was too wet. We've actually had a couple times here in the last few years where it was too dry and that people break breaking shanks on applicators, and they quit putting it on. Regardless, I mean, there gets to be the perception of we've got all this more nitrogen to get on this spring than normal. We gotta figure out a way to do it, and then you'll start getting the calls like, well, it's frozen in the morning.
Brad Carlson:We can traffic on in the morning. Then later in the day, it thaws out and it gets muddy. You know, let's go out there and put that urea on while it's frozen yet this morning here in March or something like that.
Daniel Kaiser:In in that case, I mean, as long as you don't get a runoff event, as long as the this so I mean, it's probably not as big of an issue. I mean, it's really the if the the ground is completely frozen or if I hear some of these people talk about putting it on top of snow, it just makes me really concerned at that point because that ground is frozen. Even if it's in the fall, you're likely gonna see just straight up urea leaving the field once the snow starts to melt in the spring if it can't go downwards into the soil profile. And, you know, people talk about fertilizer containing salts. I mean, we use salt to dissolve ice on roads.
Daniel Kaiser:It does it's there's not enough in your field to thaw that ground to counteract some of the issues. So it's one of the things that you really stress is if that soil is frozen, it doesn't look like it's gonna thaw, I would not be putting fertilizer, any fertilizer source on that because it's all water soluble, and it will likely leave in the spring where your wherever your water is gonna go, it's it's gonna go with the water.
Brad Carlson:Well, not to mention the fact that that when it does thaw, you know, if if we're talking about freeze thawing happening in a in a single day here, you know, that that obviously, if it's too muddy to drive on later in the day after it thaws out, that you're also dealing close to the point of saturation. And so you'll dissolve those ureapril, then they'll just be spread thin over the surface. And now you're you're subject to urease and potentially having a blow away with the wind too. I mean, if if if it's a case where there's actually capacity for it to get into the soil, well, then it's probably not an issue of just waiting to apply when it's not frozen either.
Daniel Kaiser:No. And that's one of the things that I don't understand from a grower standpoint. I mean, I know there's some pressure. It can be some pressure in terms of getting the nitrogen on and be some concern that you're not gonna get it on in the spring, but the issue with the situation like application to frozen ground, that's just essentially assuring that they're gonna have to come back for another pass to make up for what's lost. So in in effect there, I mean, I think then the decision is, if you're in a situation like corn following soybean, I mean, it's not unrealistic in that situation to think that you could go in and put all your nitrogen on as a side dress application and not have to worry about it in the spring.
Daniel Kaiser:I mean, especially if you're going in with any sort of pre emerge herbicide, put a little UAN with in with that, to give you a little bit of added time to get the nitrogen out there and and then just look at what you have for options for in season application because there's a lot of flexibility out there, and that's, I think, the problem with you kinda get really hemmed in on just the things that to be done a certain way. I mean, the main thing is looking at what options you have and then just trying to see what's best because, you know, putting the nitrogen or any of your fertilizer at risk where it's gonna run off the field where you're gonna just gonna have to come in again anyway, it doesn't make any sense, both environmentally and to the pocketbook because then you're spending more money that you didn't need to spend.
Brad Carlson:Yeah. And I we talk about this in some of our other discussions related to the four r's, but we really like to see urea worked into about really the loss percentages goes to almost nothing if it gets to three inches deep. You know? So from that standpoint, if you're looking at applying it in the spring, tillage is important. And if you're not able to till, if it's if it's not the field's not conducive to doing tillage quite yet, you know, maybe you're a little bit early.
Daniel Kaiser:And the recommendation right now really is the depth of three inches within four days. If you if it can be or you get rainfall at least a quarter to a half inch within four days of application, then typically, you don't need to look at something like a urease inhibitor, and there's a lot of good products out there. That's where what I don't understand with at least with the on the urea side is we have options. I mean, a surface application with the urease inhibitor, while it's an additional cost for that inhibitor, it's still better than, like, having to buy more fertilizer and come back with that second pass later on if just to if you're trying to offset, it doesn't make a lot of sense.
Brad Carlson:Yeah. So I guess just kinda wrap things up here. We've been talking about placement. It's probably the the least important of the four r's when it comes to reducing loss. It does play somewhat of a factor, but we certainly don't want to go without discussing it, and so that's what we've been doing this morning.
Brad Carlson:And and, really, I think it it gets more into, you know, kinda like we've said with all the four r's is you need to look at your conditions, and the whole concept of the four r's is that none of these, you know, the rate, the timing, the placement, the source, none of these things are in a vacuum. And so if you're making that total package decision that's appropriate, for the circumstance, you know, then, you know, every all the rest of us gonna just kind of fall in place based on what what the conditions are like.
Jack Wilcox:Brad Carlson, Extension Educator from Mankato, and Daniel Kaiser, Extension nutrient management specialist from Saint Paul. Thanks very much for the information.
Brad Carlson: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.
