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The Illinois Nutrient Loss Reduction podcast explores efforts to reduce nutrients in Illinois waterways from agricultural runoff to municipal wastewater with host Todd Gleason and producers Rachel Curry, Nicole Haverback and Luke Zwilling with University of Illinois Extension.
Read the blog at extension.illinois.edu/nlr/blog.
NLRS-Episode 79.
ifr260130-026
**NLRS Episode 79 | Why You Should Use the N-Rate Calculator**
John Jones, Soil Scientist - University of Illinois
Gary Schnitkey, Agricultural Economist - University of Illinois
Laura Gentry, Water Quality Specialist - Illinois Corn Growers Association
Todd Gleason: This is the Illinois Nutrient Loss Reduction Podcast episode 79: Why you should use the N rate calculator? A presentation from the annual Farm Assets Conference. I'm University of Illinois Extension's Todd Gleason. Well, during the December Illinois Extension conference, we were joined by a panel of experts: John Jones, a soil fertility specialist from the University of Illinois; Gary Schnitkey, an agricultural economist also from the U of I; and Laura Gentry of the Illinois Corn Growers Association. In an era of fluctuating input costs, these three believe corn production is about maximizing profits rather than yields. Today, you'll listen to them break down how the N rate calculator and the Precision Conservation Management program are helping farmers protect both the local watershed and their bottom line by finding that sweet spot for nitrogen applications. We'll begin with soil scientist John Jones.
John Jones: I'll show a quick snapshot of the Corn Nitrogen Rate Calculator website on the left, some data from some sites for some of the trials that we're running this year, but this is really more of a reference slide of the snapshots from the Corn Nitrogen Rate Calculator website, and this is really the landing point for the database that feeds into the guidelines that we communicate out of University of Illinois Extension. You'll see the URL up there. You can select your region in Illinois, your previous crop, and then enter the price considerations for corn and for fertilizer. You can do it on a per ton or per pound of nitrogen basis. And then that will kick out an output that you see in the bottom left, there's also some graphs and figures and summaries, but essentially, if you haven't seen that before, this is the default output that will occur. We've got some exciting projects to look at how we can refine that to a more granular scale, but not necessarily have the data to communicate that yet. But one exciting thing is that we've really ramped up the data production side of the amount of response to nitrogen data going into this effort. They're a little hard to see on this screen, they're supposed to be U of I orange, but you can see the dots across the state. Annually, in the past few years we've usually ran under the advisement of Dr. Nafziger and Dan Schafer with IFCA, around 30 to 40 trials a year, and we really kind of ramped that up this year and this summer, I think we ended up having about 91 response trials around the state. And I think that's a pretty realistic number to continue on. These are a combination of on farm and small plot trials, about 85% of them are on farm strip trials. So we're pulling data off of commercial scale investigations on nitrogen rates, some on nitrogen timing, and the idea going forward is we'll have some pretty comprehensive reports for those individual farmers involved in the trials, but then summarizing some regional data as well. So if you don't see a dot around where you're farming, come talk to me and we'd love to work with you on some on farm research. This is again a table that I think can maybe be referenced more in discussion, but this is just output from the calculator. And it's in the context of specific anhydrous ammonia prices. We look at the .5 up to .52 range that might be considerable when we start thinking about spring end prices. But this is a different way that that data is summarized. So looking at moving from regions in the North, Central, and Southern Illinois, previous crop, and then the pricing scenarios. One thing that you'll see is there's only one single value here that's communicated. So I'll go back and show the output of the calculator, on the bottom left of the screen here you'll see a range. And that profitable range is communicated as a $1 per acre range in maximum return to nitrogen or the economic return to that last pound of N that was applied. So I'm not showing the ranges here in this table, but generally they're about 12, plus or minus 12 to 14 pounds of N on each side of these values. If you've used the calculator in the past and you've maybe looked at it recently, one thing that we did, so the numbers should change because we update them annually, and this year we also started dropping data that was over 10 years old. That was another change. Previously it included data back to 2006, and we just thought some of the yield levels and some of the more cropping system components in there, some odd years didn't really represent our scenarios that we're dealing with now. So the data should look different in the winter of 2023 moving into the winter of 2024, and now will be updated eventually with the 25 data. Something we did drop was the continuous corn consideration for the southern part of the state. If you are growing continuous corn in the southern part of the state, from the data that we at least have, and we don't have a lot of trial data, and that's why I dropped that option in the calculator, was because the data was over 9 to 10 years old and I just didn't think it was rigorous enough to provide a recommendation from. So we recommend, and there's some language up there about following the corn after soybean N rate, if you are growing continuous corn. But you can also advise that or adjust that depending on previous crop production in your given field. This is just another way of showing those ranges. So if you again go from corn following soybean on the top, corn after corn on the bottom, North, Central, and South. So again, it's just a different way of communicating those ranges. You'll see those N numbers, that's the number of trials that is represented in the output of the data. And I think that's probably one of the strengths of this process of identifying optimum nitrogen rates and communicating them, is that it's a very data driven process. So this is, I'll say probably one of the higher amounts of N rate trials that any state in the country has ran to create a database that we can have some trust and replicability of. These are just some other on farm research trials that we've got in our research group going into 2026. If you're interested feel free to reach out on those. I'll say one thing on P and K if that's all right, but when looking at our, so one of the large efforts that we're doing is also working on updating phosphorus and potassium recommendations. There's a large network of trials going around the state. And what we usually do with this as well is look at the yield response to phosphorus and potassium fertilizers, but also look at the ROI to those fertilizers. And sometimes categorize that in different crop price scenarios. And the thing that we're looking for is that this breakeven point matches what we're seeing and where we're plateauing in yield. Or where we stop seeing a yield increase with phosphorus or potassium fertilizers. I think this gives us a little more confidence in the recommendations and guidelines when we're comparing yield responses to an ROI consideration. So I'll stop there and we'll just have these slides for options, but you can cut those off if you need to.
Todd Gleason: And I want to take you back to some of the slides to begin with. First, if you want to find the N rate calculator, search Google N rate calculator. It will show up, um there is you can do corn n rate calc.org, but search Google for N rate calculator. I do have a couple of questions. Oftentimes for our part of the world it will come up around 185 thereabouts, 185 pounds of N that need to be applied. What variables can a farmer input? So can they input the price of N?
John Jones: Yeah, so there's four main variables that go into this. Your region of the state, your previous crop, the price of corn, and then the price of nitrogen fertilizer. So those are the input variables that are living as the calculator sits right now.
Todd Gleason: So you can say I expect to raise 200 bushel corn or 225, and I think it'll be worth $4.20 cash and it will...
John Jones: There's no yield number that's an input. So it's just the price of the corn.
Todd Gleason: Oh there's no yield number!
John Jones: Because we found a not a strong relationship between the yield at optimum N rate and the optimum nitrogen rate that's applied.
Todd Gleason: Ah gotcha.
John Jones: Due to the colors of soil you see on the map. Um so you just input the price of corn grain.
Todd Gleason: And then it gives you... it optimizes the nitrogen rate for...
John Jones: It shows the nitrogen rate that pays for the last bushel, or excuse me, it shows the nitrogen rate that produces the last bushel that pays for the nitrogen. So the last pound of N applied is paid for by the last bushel produced.
Todd Gleason: So it shows me 185 pounds of N, is that what I set the anhydrous rig to?
John Jones: That is not what you set the anhydrous rate to, but that would be what you'd you'd that's a product base, but these are the pounds of N per acre.
Todd Gleason: Right, so you're counting how much, you're counting N and what else? Nitrogen applied, plus what else?
John Jones: Nitrogen applied. So you can also because you can choose your fertilizer source, it will give you a pound of product output as well. So if you see the pound of nitrogen applied, for this scenario, the optimum N rate was 183 and the pounds of anhydrous would be 223.
Attendee: Does that include nitrogen from MAP and DAP?
John Jones: This includes all of the N that's applied. So when we look at the data set...
Todd Gleason: When you see the 223, you have to subtract your MAP and DAP and those things. Right, that's what I was trying to get to. I'm sorry, I was getting there the long way around I suppose. But this is not the number, this is not the number you apply.
John Jones: That's the number just total end, because there's only an N source indicator there. So this kind of brings up another ongoing effort that we've got right now to build a state-specific calculator that has more options. And we're working with some other collaborators at U of I to do that so that we can maybe get a little more granular than just North, Central, and Southern Illinois. Splitting things like prairie and timber soils and different soil associations. One thing about the data that's included here and interpreted is it does count all nitrogen that's applied in the fall as MAP and DAP and your specific N source. And the decision to do that is really comes from research results where we've compared the available N in fall and spring applied DAP and we did not see a difference between those two or spring applied UAN. So the fall N could be counted on in your total N budget.
Todd Gleason: Okay I know you'll get this question so I'm gonna ask it. I'll ask you a question first. Who remembers the nitrogen formula for the state of Illinois? Anybody? I'm sure you used, some of you used it.
Attendee: 1.2
Todd Gleason: There it is, yeah. I won't say it out loud, but that's the one I'm talking about. Minus 40 pounds for... and we always get asked... is there an end credit for soybeans here, and it doesn't appear to show up, why?
John Jones: The answer is that the change in available N, soil available N from a previous crop of soybeans and corn is already represented in how the data is interpreted. Because you pick your previous crop, we have N rate curves or response curves to nitrogen for both scenarios. So when you pick your previous crop, we're already seeing how that corn would have responded following corn or soybeans. So the change in soil N availability after corn and after soybean is already represented in the dataset. We don't really call it this the credit the way that that the 40 or 50 pounds would have been considered before. Interestingly enough to the 1.2 number, I wish we'd just stop talking about that because most...
Todd Gleason: That's why I didn't want to say it out loud!
John Jones: Most farmers if you look at your N budget are nowhere close to that. And that's considering the output of this or not, when we look at on farm research, we're bouncing between 0.85 and 0.95 more likely than not. And so I think we need to stop mentioning that number in decimal and go off to some results of relevant data.
Todd Gleason: The first time I heard the 0.9 number was in the mid 1990s, mid to late 1990s. At some point, but we were well above that using still the old 1.2 formula at that point. Let's turn our attention to a long-running research project now called PCM, Precision Conservation Management, that the Illinois Corn Growers started to put together. I'm going to let Laura give the history on this one with Gary Schnitkey at the University of Illinois. But Laura why don't you start with kind of the history and background about precision conservation management. This on the flip side is about nutrients coming off of your properties and trying to control them in some form and what might be the best opportunities to do that in a whole bunch of different ways. Laura?
Laura Gentry: Thanks, thanks Todd. So everybody, cast your memories back, back to the fall of 2014. And think about what that fall was like, if you remember, and it was already referenced up here once today, the Des Moines Water Works lawsuit. Does everybody remember that? So that was happening in the fall of 2014. And then there was also, who remembers the huge algal bloom on Lake Erie that fall? That late summer and fall, does anybody remember that? When nobody could drink the water, nobody could cook with the water. You couldn't even give your dogs and cats the water. They were warning you about even bathing because it was a harmful algal bloom. That was happening at the same time. The city of Toledo, Ohio at that time was under a do not drink the water ban for a couple of weeks. There was just a lot going on in the fall of 2014, and back here in Illinois, we also had the Illinois Nutrient Loss Reduction Strategy was about to be released. It actually came out in July of 2015. But we had all the stakeholders were engaged in developing that Nutrient Loss Reduction Strategy. And here at Illinois Corn Growers, we knew that that was going to be a really relevant document that when it came out, everyone was going to be talking about it in the Midwest and maybe around the country, because it wasn't just Illinois, there were a total of 12 states that had to develop the Nutrient Loss Reduction Strategies, they called them nutrient reduction strategies, Illinois is the only one that referred to ours as a nutrient loss reduction strategy, emphasizing that it's not that we want to reduce nitrogen, it's that we want to reduce the loss of the nitrogen and the phosphorus. So 12 states were doing this, so it was a big deal all up and down the Mississippi River at that time. And it was just clear that there were going to be long term ramifications from that document. And in response to that, Illinois Corn, and a lot of other agricultural groups in Illinois as well, were thinking about how we were going to address water quality issues. And Illinois Corn started a program in 2015 called Precision Conservation Management, PCM. And we launched it in 2016 with the help of a Regional Conservation Partnership Program grant from NRCS. We got 5.35 million dollars to start that program. And that was a ton of money back then. That seemed like a lot. And it was a, well it still is. Yeah, if it's just yours, it's a lot. But we are now on the 10th year of PCM. And the whole idea behind the effort of the Precision Conservation Management program is that we work one on one with farmers, so every farmer who enrolls in the program has a, we call them a specialist, a precision conservation specialist that works directly with them. It has a very strong data component, and these guys, I look at them because they both know very well all the different pieces that go into it. And we sit down with farmers two to three times a year and collect data, and we put it into our secure data platform, our farmer portal. And it includes information about your management decisions. So every farmer puts in information about every pass that they make across their field, and the details of that in terms of what their equipment that they used were, what was the pass for, was it a tillage pass, a spray pass, planting, harvesting, and we assign the equipment to that, and the inputs, were you applying, were you spraying an herbicide, a fungicide, were you applying a fertilizer, how much of the fertilizer, what type of fertilizer. And so it's got quite a lot of data points in there. But our specialists are there to ease the pain points of getting that data into the program. So it's a very data intensive program. And every year in February and March, our specialists come out to the farmers in the program and deliver a custom-made report to them, a RAP report, a Resource Analysis and Assessment Plan. And that RAP report spells out all the different, the data that we took, summarized by field for that year and all previous years, and it shows it to them in terms of their tillage decisions, their nitrogen management decisions for corn, and their cover cropping decisions. And then it allows them to be able to compare their own economic decisions, their own economic outcomes and agronomic outcomes, with those of farmers who are near them, like in the same region, of course not by name or by field, but at an aggregated and anonymized level, the farmers can say, 'oh, this is my one pass tillage system with a vertical till for my soybeans, and I want to compare it to how farmers were doing who grew soybeans with no-till, or with two tillage passes.' So it's a benchmarking type of system. And what Dr. Schnitkey helps us to do is to take and assign costs for every single one of those passes that they make, we assign costs using data that he gives to us. And so the farmer can actually compare their their own net bottom line with those of farmers who are using other practices. And so that's the big idea behind the biggest part of the Precision Conservation Management program, helping farmers to make decisions, financial decisions about conservation.
Todd Gleason: Gary how did you get involved?
Gary Schnitkey: Todd don't sound so impressed. I was, I just wanted to get to Gary. I was just gonna skip the rest of the way over you. So, that that year I did a sabbatical with Illinois Corn and that was one of the things that I worked on was helped developed the procedures for collecting the economic information associated with PCM. He went on vacation with Illinois Corn for a whole year. So you can look at it that way. Most people would pick a different place to go. Just so we all know that. Usually it's a sabbatical overseas somewhere. But Bloomington is a good place to go by the way. Yeah I was happy with that.
Todd Gleason: In the 10 years of data Gary, what are the most striking things you have learned?
Gary Schnitkey: So well we'll start with nitrogen. You know that MRTN? PCM would show that that is correct. That that 170 to 180 pound range is is the profit maximizing range. We do see higher yields occasionally above that. And that's not every year but on average it's above that. But the additional bushels do not cover the cost of that. And that's particularly important now, because you're going to have $4.20 corn and $850 anhydrous ammonia. That's what I looked at, that's the last value from the Illinois Production Cost Report. So you're looking at a relatively low corn price, high price input. So if you look at those those charts, John was using 4.50. I that would be optimistic by my by my ag economist look at things. The other thing that's really interesting, and by the way there's a lot of farms that apply well above that level. And we're talking well above that level, so we're not talking slightly above, well above. If you're higher than MRTN, you're doing this is the prediction that I would look get from that data. If you're above MRTN, you're doing more tillage, more passes, applying nitrogen, you're applying more fungicides and you're applying more herbicides. So, and that so by the way, and that's most people. So when you're above in one profit maximizing level, you're likely above in all of them. So here's what I would tell you is maximize profits, not yields. And I would and you know there's only prob- probably about only one person that comes out to your farm that suggests lowering inputs. And that person won't, but the person is the FBFM field staff who says cost matter, right? The rest of the people we can spend $10 and we'll get an ROI of 150%. I mean that that's pretty much the sales, and you add up all those sales pitches and we have inputs that are well above the profit maximizing levels. So maximize profits, not yields.
Todd Gleason: There's a lot of room for improvement. Did the ag economist in you put a number on how what that dollar bill amount is per acre?
Gary Schnitkey: So, you know, when I it's significant and again, we see this all and it's not just PCM, it's FBFM as well. Farm Management, you're in a commodity based business right, corn and soybeans primarily, commodity based business. The way an commodity based business producer differentiates themselves from the other people is lower cost. It's the only way. So if you want to maximize profits, you have to have lower cost. And, you know, if if you begin adding it all up, you can get $40, $50 per acre pretty quickly. So.
Todd Gleason: So it's about efficiency then, PCM is, to some extent. And about, well and, Laura, about avoiding regulation in the future I think, is one of the, had must have been one of the reasons that the program began to begin.
Laura Gentry: It was entirely the effort around it and knowing what was happening with the Illinois Nutrient Loss Reduction Strategy being released, all the other black eyes for agriculture that were happening back in that period of fall 2014 and 2015, there it was all around concern of regulation and and it was more than this idea that many people have about you know, keep the government out of my business, it was about maintaining the flexibility that we had and you know, we'd already lost a great deal in terms of other regulatory requirements, but this was about maintaining the freedom that we have to be able to respond to climate issues, to markets, to other economic factors that we need to have some flexibility around without the constraints and being hamstrung by onerous record keeping and regulations around our fertilizer applications.
Todd Gleason: And I think, but I'm not sure that this is the right timing, one of the things that came up at the very end of the policy section was the Des Moines Water Works and that was an issue. Uh it was a scary issue at about that time, am I right?
Laura Gentry: Oh it was, yes, every everybody in, every farmer in the Midwest was aware of the Des Moines Water Works lawsuit and was keeping their eye on it at that time. Every ag magazine that came out had an article about what was happening with it.
Todd Gleason: John I suspect you learned a lot about that over time. Uh and you and your agronomist friends probably talk about the movement of nitrogen and other things through the water systems. How well and how easily does it move? And what happens when you over apply?
John Jones: We've got a leaky system by nature. When we look at the amount of water, nitrogen is going to follow water in most cases. Both up and down as as we lead to water induced volatilization losses of nitrogen into gaseous forms or if we lose nitrogen leaching through tile lines, or if we lose nitrogen leaching through non-tiled fields that tracks right along a fragipan if anyone's in Southern Illinois and has fragipans or root limiting layers that are about 24, 18 to 24 inches deep, water can track horizontally on top of those as well. And this is just an inherent part of the system, it's leaky. And one of the interesting things that some myself and some colleagues have found when looking at what nitrogen is found in the tiles is it's not necessarily fertilizer nitrogen. The majority of that nitrogen is from organic N in the system that's been mineralized and then lost. We have a lot of organic matter in Illinois soils. We've introduced oxygen in many different ways and it burns up organic matter, that's also how our plants get get nutrients, is that organic matter has to burn up. I think there's there's three things maybe related to what we've talked about so far that I would want to hit on. One is that interestingly enough in the, if we're talking about yield levels at at different rates of nitrogen that are applied, the difference between the N rate that maximizes yield in a lot of our trials, and they're they're very relatively high yielding trials, when most when the mean average is 268 to 272 across a wide range of soils in the state, um it's about one, one to two bushels is the difference between maximizing yield and then maximizing profit. And that's not always the case, some sites the the bushels or the yield drops a little bit more when you get down to the economic optimum nitrogen rate, but it doesn't vary that much. And in fact that's one way that we check our data set to see is this maybe an odd site year or odd trial is we look at the difference between the N rate or the yield that or the yield when it's maximized versus the yield that led to an economic optimal N rate. Two more things is that interestingly when we look at nitrogen losses and what nitrogen rates exacerbate that, we really don't see a big difference between I'll say 30 pounds of N applied, so if you only put starter N on, versus the optimum N rate around 175 to 180. It's after that, and the 30 pounds after that rate that we start to see an exponential increase in nitrogen loss. Interestingly, we see that the same way in phosphorus. The soil test level that optimizes yield with P, that between zero P applied is generally no no difference in P loss in surface runoff or through tile lines. And that was part of the work that I did in graduate school in Iowa. Speaking of the Nutrient Loss Reduction Strategy there, a lot of the research that fertility specialists around the Midwest have done is present in a lot of the Nutrient Loss Reduction Strategy targets and application or practice efficiencies. But with phosphorus it's the same thing. Not until you increase soil test phosphorus 20 to 30 parts per million past the agronomic optimum, that's when you start to see exponential losses of P both sub-surface and with runoff. So I think those are something to to think about and maybe it's not always talked about a lot is that agronomic efficiencies also usually parallel with environmental efficiencies in reducing losses.
Todd Gleason: Thank you, that is a really insightful uh thought. I I had not come across that one. In PCM, you talked about efficiency some, the number Gary of passes, tillage passes. Um, first, I don't know whether and Laura you may have an idea, I don't know whether this is related to keeping nutrients on the property, probably is, um, but it certainly is related to efficiency and maximizing efficiency. Gary, can you talk about the number of passes and tillage passes that is?
Gary Schnitkey: So PCM regularly summarizes data in and and we do it in no-till, one pass, two pass, and two plus pass systems. And you'll see that if you go to the business case for conservation, you'll see that on on the website. The one pass systems versus the no-till systems will often have roughly the same profitability uh sometimes a little bit higher sometimes a little bit lower, there does appear to be a a yield a bit of a yield advantage for one one pass sort of system. When you go to two two and two plus pass systems, we don't see an increase in yields, and all you're doing is, if you're not getting an increase in yields and we don't see a reduction in uh in herbicide or pesticide costs. In fact pesticides don't vary much depending on on on on the on the tillage system. Um you know if if you're not getting a yield advantage, all you're doing is adding cost. I mean well and we're putting in uh every tillage pass will be roughly 15 dollars an acre so you see a sort of that reduction in uh in in returns.
Todd Gleason: And from the water quality side, how much difference does it make or from we've had issues with windborne dust storms as well in recent years.
Laura Gentry: Well from the water quality side and I was going to add this on based on on John's comment about uh it's that it's the extra you know 25 30 pounds that farmers are putting on of nitrogen that that insurance nitrogen that they're putting on to be sure they're not leaving any any yield on the table. It's that amount that they're losing that's coming out of tile lines and that is going to if we don't curtail this loss of nitrogen leaving through our through our tile lines it is very likely to to result in in lawsuits or additional regulations down the line and and I don't say this to scare anyone I don't say it cause it what anyone wants to see happen I just it is the most likely scenario for the next line of regulation in the Midwest um is going to be around water quality issues. And this is what I think is so interesting um Lowell Gentry, my husband, I guess say, but his work in Central Illinois finds that the average nitrate nitrogen losses from tile lines is 27 pounds of nitrogen per acre. And you just heard John say that it's it's usually and and I'm comparing myself, the MRTN values with what the average uh PCM farmer is applying, it's anywhere from well there was a low number in 2021 farmers the average nitrogen above the MRTN it was only 8 pounds the average farmer only applied 8 pounds above the MRTN that year, but in all other years that value is ranging from 25 to up to 48 and that's the average, pounds above the MRTN. And the MRTN works, it literally is, it's an it's an economic model and it does exactly what it's supposed to do, it it does predict the most profitable nitrate nitrogen rate. And in the PCM program the only years where we have seen that it didn't work were in those years when the soil, when the soil conditions were just perfect or the weather conditions were just great and the soil released more nitrate than it than it was predicted to. And in those years the MRTN overestimated the amount of nitrogen needed. It has never once Todd, never once in the work that I've looked at, under predicted the maximum nitrogen rate. So farmers can feel like it's a good conservative estimate and very few farmers seem to believe that and Emerson says it all the time, it's a conservative estimate, but John do I mean do you feel comfortable with what I said there?
John Jones: No, but when you say conservative, you mean we're going to get most of the yield.
Laura Gentry: Yes, I mean it's under, it's um it's it's predicting a nitrogen rate that you will not be under applying nitrogen at the MRTN. That's what I'm trying to say and if you want to correct or add to that.
John Jones: No, I'd agree with that. And one of the ways that we show that in some of the data sets is you'll you'll see a a percent yield achieved and it's usually at 99%. Um when we think about these studies. And one of the the you know I'll say criticisms maybe of this approach is that yield isn't considered, we talked about that earlier. Um but there's the the lack of relationship between yield and optimum nitrogen rate made up really caused by the amount of of nitrogen from our soils is the difference there. Now there's certain cases in the southern part of the state where you have relatively lower nitrogen mineralization rates or conversion to plant available, there's a little more of a trend between yield level and optimum nitrogen rate. Um one of the things that that I think is important though to to to break apart there though is that the yield level isn't necessarily kicking off any any need for more nitrogen. The question of does the does that corn plant need more nitrogen when it produces more kernels is yes. But what we're finding is that the soil keeps up in many cases with that additional requirement of nitrogen. A corn now interestingly enough as well, what we're finding is reductions in nitrogen concentration in the grain as we've increased yields over time. So there's there's some evidence that our hybrids have become more efficient at using available nitrogen that's present as well. And so all of this is happening at the same time. One thing that's really interesting in the data set is we look at the yields at zero nitrogen or zero to 30 pounds of N which may have been the lowest nitrogen treatment, those are increasing steadily over time. What's the difference? Breeding, really. I mean a lot of good things happen when you breed for higher yields. Things like nitrogen use efficiency, leaf angle orientation, everything like that. Um when you breed for higher yields, other components of that plant usually are optimizing themselves to to create those more kernels per per plant.
Todd Gleason: I've got a question. One trip comparison if I fall strip till nitrogen is that one trip?
John Jones: The question is strip till would be one one trip across the field and we would separate out the, but yes it's one strip unless you're freshening it and then you get two passes but uh one one trip.
Todd Gleason: Other questions?
Attendee: Okay it's it's all well and good to do this but are there anything coming down the pike to help us out, like we've been tissue testing, we're looking for something to to measure mineralization during the season so we can we've been told spoon feed nitrogen through the season. Is there anything out there that we can say in April, May, June and see how the mineralization is coming because this year we raised 280 to 290 bushel corn on that same thing and for no reason, it was dry at the wrong times and all that kind of stuff. So is there a way to figure this out?
John Jones: Yeah, so one of the things that we implemented this year, I feel in production agronomy research you're either coming from the top up or the bottom down. I'm a soil scientist by training, soil chemist by and so I always call soil fertility is soil chemistry with dollar amounts. And and I think what what we've implemented this year in a lot of those trials and we haven't got the data all analyzed yet from the yields is that we're measuring soil nitrogen at different times to create a database to predict that. So the the you know the soil testing for nitrogen kind of boomed and busted. Uh there were certain states that ran pre-plant nitrate tests, pre-side dress nitrate tests. Um there was a presence of kind of um an organic mineralization proxy of the Illinois Soil Nitrate test that existed for a while. But they've all boomed and busted and and the challenge has been if you're just measuring nitrate that it's a very quick snapshot of what's available there. And it's more of a site characterization than you can say you need to apply 150 pounds from a 18 part per million PSNT pre-nitrate sample. Um so there's work on that. I would say we don't have the tools yet to say this is the end mineralized. There's some efforts in modeling and and that's really where we have to combine a lot of the work our group does and we try to measure everything. We we're uh in the lab and in the field quite a bit collecting a lot of data. We're working with modeling teams like uh Dr. Kaiyu Guan's group at University of Illinois, to say can now can we start to predict that. My hope is that you take an and this is again kind of pie in the sky moment but I I don't think it's worth uh I don't I don't think it's bad to shoot for these things. Is that you start out with the optimum nitrogen rate that's maximized profit in the last 10 years data set. And as you move to incur different environmental changes in a given year, that adjusts to consider what you're talking about. Did we have, were we coming out of a dry fall where there happened to be residual nitrate. Usually residual nitrate in let's say fall of 2012 got flushed out pretty quickly in 2013. And that was why there was a big um I think it was the N Watch program that that Dr. Brown uh worked on and um and Dan Schafer and Emerson did as well looking at what was hanging out there. And my hope is that then as those processes are occurring that's leading to more or less soil nitrate availability we can adjust that optimum end rate. Are we there yet? No. just simple answer. Um but we're trying to come up with proxies and circuits to look at that. Just just so you know, every time a spoon feeding nitrogen means more passes across the field. Every one of what's that? Unless you're irrigating, which maybe. Every time you go past the field, there's a cost. Just just just uh remember that.
Todd Gleason: So I wanted to ask uh both John and you can jump in Laura on this too but I think it'll be data that that Gary has worked with. Is there very much of a difference in when the nitrogen is applied, so whether you're fall apply, spring apply, side dress, how how many times you make a pass and I think I want I want John, I've heard Gary's several times so John what what what do you know about this and what does your training tell you?
John Jones: Sure, um we've got a few papers in review on this and and we talked about this this summer at a nitrogen use efficiency conference. Um so one of the things that's interesting when we compare optimum nitrogen timings to when, we'll say that corn plant is taking up seven pounds of N per acre per day. Is that the fertilizer timing research doesn't necessarily align saying you have to have your N you put your N on exactly when the corn plant is taking that up. And that's because of what happens to fertilizer when we immediately apply it. It could a little bit make it taken up by the crop immediately, but a lot gets mixed into the cycling of microbial biomasses or dead microbes in the in the soil. Your fertilizer gets immobilized pretty quickly. So the timing research is a lot more muddy. Now where there's some more clear trends, uh so the paper we've got in review right now is a comparison of all spring or all fall anhydrous ammonia, what's the difference between optimum nitrogen rates and yield. We don't see any difference in yield between our optimum nitrogen rate being applied all in the fall with anhydrous and all the spring. Now there's some big big risks to take with doing that. And I don't think many people are putting all their all their end on in the fall anyway. But the the comparison is kind of a stark contrast. And there's about an 18 to 24 pound N optimum N difference or lower optimum N with the spring end. When we start to compare timings after planting things get a little more muddy. Um in the southern part of the state where you can lose a lot of end by volatilization, let's see if you just surface apply UAN, and dry conditions like this year, then it pays for getting it knifed in at side dress versus a later Y-drop where you're just setting it on the surface. Everything is always going to be environmentally dependent on what that corn crop sees in a given year. But that's probably the biggest challenge. And I think one of the things that's shown up in a lot of nitrogen timing research and we've got a new project this year looking at that that'll be on long term across the state, is that getting at least half your N up front usually pays off when we have those low nitrogen availability years. Now the challenge I think and what I'd like to see is our ability to adapt as between planting and V6 environmental conditions come about, then you can adjust maybe what your side dress rate is going to be. Because in earnest what what the major decision is is what your side dress end rate adjustment is going to be. Sometimes whatever your base rate end is, is what it is for your for your whole farm maybe, unless you can start to vary that. So that's something we're looking a little more into is how do we really dial into not just a total end rate recommendation but specifically that side dress end rate recommendation.
Gary Schnitkey: So in PCM we divided up by uh fall, mostly fall, mostly pre plant spring, mostly uh post plant and then there's three way applications. Fall does not turn out to be the most profitable, does not. And the primary one of the primary reasons is the nitrogen inhibitor that goes on with it. And that's typically a 14 to 15 dollar cost. So even though you're putting anhydrous ammonia on, you're adding that 14 to 15 dollar cost. Um you go pre and post plant, we don't see much difference in in our in our data whether most is pre plant, most is post plant. I would note that if you want to put uh nitrogen on the least expensive way, put it on as anhydrous ammonia. Um and that has its own sort of issues. The three way did not also did not have the highest uh profits. And one of the things that's going on there is you got three three three three passes through the field. And the other thing for whatever reason the three passes through the field follow the same thing that they do a lot of other things, so they also had higher nitrogen rates. So I the the so if we could find some three pass systems with MRTN rates we might see something different than than what we then then what we've seen. Those do have differences as far as losses which uh uh Laura might might want to say something about but they're they're the obvious ones. You know the one one thing I would say is don't forget that every time you go across the field you're adding cost. So you know uh spoon feeding three three passes, you know every pass is a cost.
Todd Gleason: Gary Schnitkey is an agricultural economist from the University of Illinois and was joined on stage by John Jones, a soil scientist at the U of I and Laura Gentry water quality specialist from the Illinois Corn Growers Association, during the annual farm assets conference. Our presentation today from the Illinois Nutrient Loss Reduction podcast was produced in conjunction with Rachel Curry, Nicole Haverback, and Luke Zwilling. I'm University of Illinois Extension's Todd Gleason.