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Episode 26 | Maximizing Corn Yield Profits & Minimizing N Losses by Illinois Extension
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.
Episode 26 | Maximizing Corn Yield Profits & Minimizing N Losses
00:00:06:05 - 00:00:31:11
Todd Gleason
This is the Illinois Nutrient Loss Reduction Podcast, episode 26 Maximizing Corn Yield, Profits and Minimizing and Losses. I'm Illinois Extension's Todd Gleason. You know, land grant universities throughout the Corn Belt have been working for decades to adopt a nitrogen strategy that optimizes yield and maximizes profits. This has culminated with the online Nitrogen rate calculator that can be used in several Midwest states.
00:00:31:14 - 00:00:53:15
Todd Gleason
The data that drives the calculator is derived from the most recent nitrogen rate studies in each individual state. And by default, this calculation limits nitrogen applications to maximize profits for corn, not the yield. It also, by design, works to limit the nitrogen losses, says Illinois Extension agronomist Emerson Nafziger.
00:00:53:22 - 00:01:02:19
Emerson Nafziger
Well, one of the real quandaries is we know that the corn crop needs nitrogen, and we also know that nitrogen moves out of tile lines and into water.
00:01:02:19 - 00:01:31:12
Emerson Nafziger
And so this is the was our our goal is to give the crop just enough. And our hope is that it doesn't leak any of it out into the water. That hope is one that's almost impossible to realize. If you're going to grow corn and you put enough nitrogen on to get its yields to water. The corn has the capability to yield.
00:01:31:14 - 00:01:56:00
Emerson Nafziger
Then it's inevitable that some of that nitrogen in our climate, because we get more rainfall than the crop needs. And so some of the rainfall, some of the water is going to move through the soil and out through the tile lines. And that's why we have tile lines. So when water moves and there's nitrate in the soil, then some of that nitrate will move with the water into the tile lines.
00:01:56:03 - 00:02:16:01
Emerson Nafziger
If there's a way to get that to zero, we're not quite sure what that would be because, it's a system that has some leakiness in it, and that's pretty much an inherent property. You know, we like the soil to keep it all and then the crop to take it all up, but that's not really the way it works.
00:02:16:04 - 00:02:39:01
Emerson Nafziger
Another issue we have in Illinois, it's not a bad one. It's one that makes us so productive, but that is that our soils have quite a bit of organic matter in them, and that organic matter has nitrogen as part of it. In fact, about 5% of the organic matter, the weight of organic matter is nitrogen. And that's something that, you know, not too many people think about.
00:02:39:01 - 00:03:02:04
Emerson Nafziger
But the the wonderful things that organic matter, does for soil productivity and with all the soil health talk and so on. You know, organic matter is really the, the primary thing if you have high organic matter, you have a healthy soil is pretty much the way it it appears. But that organic matter is a source of nitrogen.
00:03:02:08 - 00:03:26:18
Emerson Nafziger
Now the microbes break it down. The good thing is that it isn't going on during the winter and so on, but it goes on any time the soil temperatures get up above 50. This conversion of some of that organic nitrogen to a form that's available to the crop, starts up, and the warmer the soil gets with good moisture, the more rapid that process is.
00:03:26:20 - 00:03:53:09
Emerson Nafziger
So we have the soil organic matter producing some nitrogen that's available to the corn crop during the season. The big problem is that we're never quite sure at the beginning of the season how much that's going to be. And it it's not a big trick for our higher organic matter prairie soils to provide, say, 150 pounds of nitrogen to the corn crop, for the season.
00:03:53:11 - 00:04:19:03
Emerson Nafziger
How do we measure that? Well, one good way to measure it is to do nitrogen trials and have a zero nitrogen. So in a zero fertilizer, nitrogen, everything that the crop takes up came from that organic matter. And if we get, in round numbers, if we get 150 bushel yields without nitrogen fertilizer, which in corn following soybean is not that unusual.
00:04:19:06 - 00:04:48:06
Emerson Nafziger
That means that it took up 150 pounds of nitrogen from the organic matter. If we could have a way to know what that was going to be, and obviously in different soil types, it's different. Organic matter soils produces less. And so there's more dependance on fertilizer or nitrogen and, you know, soils with a light texture that the nitrogen can move away more easily.
00:04:48:09 - 00:05:13:13
Emerson Nafziger
But the way we've approached this is just to, do enough nitrogen trials so we can get a good idea, on average, how much fertilizer nitrogen we need to provide to the crop to give it, the yields to not maximize yield. We really want to pull that back until the last nitrogen we put on is just paying for itself.
00:05:13:15 - 00:05:50:25
Emerson Nafziger
And so we've done that and run the nitrogen rate calculator. And it says for central Illinois, corn following soybean, about 180 pounds of nitrogen at current prices is the amount that it takes to maximize, profit per acre from nitrogen over hundreds of trials. So that's that's one approach to it. But that amount of nitrogen, if the crop needs is going to produce 220 bushel yields, it needs to take up about 220 pounds of nitrogen.
00:05:50:25 - 00:06:16:05
Emerson Nafziger
And if the soil provides, say, half of that 110, then the other half, a 110, has to come from fertilizer. Well, 110 pounds of nitrogen fertilizer is simply not enough. But I think we need to get ourselves over the idea that, you know, the more nitrogen we put on this crop, the more it's going to yield, because it simply doesn't work that way.
00:06:16:06 - 00:06:20:27
Todd Gleason
How exactly are the nitrogen rate applications for the state of Illinois developed?
00:06:20:29 - 00:06:40:05
Emerson Nafziger
Well, we've over the last 20 years, we've run a lot of nitrogen rate trials. And these are kind of, cumulated into the nitrogen rate calculator. And you can go and find that online. It's pretty easy to find. Our database is is a pretty good one in Illinois.
00:06:40:05 - 00:07:01:13
Emerson Nafziger
We have for northern and central and southern Illinois and both for corn following soybean and for corn following corn. And if you go to that website, you will find that, those options. So you choose the crop, you choose the crop for the area year round, whether it was corn the previous year or soybean the previous year, and corn the previous year.
00:07:01:13 - 00:07:38:19
Emerson Nafziger
As you might expect, generally requires more nitrogen than than if it were soybeans the previous year. That's not the old 40 pound credit to soybeans we used to give. It's actually smaller than that. But there is a difference. So you do that. You put in current prices for what you want to use for corn and what nitrogen is costing you, and it will provide you sort of a best guess estimate of how much, based on all the trials that have been done, it will give you an estimate of how much nitrogen, fertilizer should be used.
00:07:38:22 - 00:08:04:13
Emerson Nafziger
We call that number the m r t n, which is maximum return to nitrogen. And that's that's just what we came up with to say this is the nitrogen rate that will will maximize your economic return to the to the amount of nitrogen you use. One last question. Are new technologies, things like crop sensing, site specific application of nitrogen helpful in meeting the NLRS goals?
00:08:04:20 - 00:08:40:07
Emerson Nafziger
Certainly we have a lot of, hope that some of this new technology, aerial photographs, satellite sensing, crop sensing of various sorts, will make nitrogen use more efficient. One of the problems is, though, that if you wait until the crop is showing some amount of deficiency, our research suggests that it may be a little too late to actually recover all of the yield.
00:08:40:10 - 00:09:15:26
Emerson Nafziger
It seems that today's hybrids need nitrogen early in the season. And if they're deficient after they come up, that you may lose some yield that you can't get back by then putting more nitrogen on. So that's a fundamental issue that's still being investigated that really actively. Certainly it's the case that, you know, lots of people were looking at all kinds of imaging and saying, well, we're certainly we can go to the parts of the field that are paler yellow and put more nitrogen there, and we can be more efficient in the nitrogen that we use.
00:09:15:29 - 00:09:34:16
Emerson Nafziger
In practice, that's proven to be a lot more difficult than we thought it would be. I haven't given up on it. I don't think anyone has yet. But, some of the early efforts at sensing the on the go with sensors, you put them on the nitrogen applicator and where it was a little darker green, you'd put less nitrogen.
00:09:34:16 - 00:09:59:12
Emerson Nafziger
Those aren't in real wide use anymore. And, I think it's because in our soils, again, because of that supply of nitrogen that comes from the soil organic matter. We've sometimes we can get corn to waste high without nitrogen fertilizer at all. It's pretty dark green. And what's the crop? You know, going to. You know, it doesn't mean the crop doesn't need nitrogen.
00:09:59:12 - 00:10:26:26
Emerson Nafziger
It just means that up to that point in time, the soil has supplied enough. That takes a warm and relatively dry, season to get to that. But we certainly have seen some of that. And if that's the case, then waiting to sense, you know, you might be waiting quite a while and and suddenly, you know, that crop runs out of that soil supply of nitrogen when the uptake demands are really high.
00:10:26:29 - 00:10:49:27
Emerson Nafziger
Well, when the crop is waist high to head high, that's about the maximum uptake rate. And, it may be really hard to respond in time when we put fertilizer out there. We're not putting it into the plant. We're putting it into the soil and hoping that it can get to the plant. So there are some time aspects of that that's just going to make it difficult.
00:10:49:29 - 00:11:15:22
Emerson Nafziger
And I think we'll get some modest improvements in that with new technology. But, I think we're also going to have to accept at some point that we have to put the nitrogen on in time for it to do the crop the maximum amount of good, and rate is the thing that we probably need to pay the most attention to, when we get it on is is a little bit more flexible.
00:11:15:24 - 00:11:23:10
Emerson Nafziger
But, certainly this crop needs some nitrogen early in order to make the kind of plant that it takes to produce the high yield.
00:11:23:16 - 00:11:38:01
Todd Gleason
Emerson Nafzigers an extension agronomist at the University of Illinois, joined us on this episode 26 of the Illinois Nutrient Loss Reduction podcast. You can find the nitrogen rate calculator online. Just search for nitrogen rate calculator.
00:11:38:03 - 00:11:59:17
Todd Gleason
Today's program was produced in conjunction with Illinois Extension Watershed Outreach Associates Jennifer Woodyard and Haley Haverback Gruber. As described in the State of Illinois Nutrient Loss Reduction Strategy, Woodyard works in phosphorus priority watersheds and Haverback Gruber's work is with nitrogen priority watersheds. I'm Illinois Extension's Todd Gleason.