Nitrogen conservation and water quality, Part 1: Tech, edge-of-field, & proactive management solutions
Welcome back to Advancing Nitrogen Smart, the special podcast series from University of Minnesota Extension. I'm Jack Wilcox at the communications desk here with Extension. Now you probably noticed the new music. We're starting 2025 with a fresh coat of paint. So don't worry. You're in the right place.
Jack Wilcox:Today in episode 15, we're gonna take a big picture look at nitrogen conservation. We spend a lot of time talking about water quality issues. What are some solutions?
Jack Wilcox:The subject is important, and there's a lot to talk about. So we're going to divide this episode into 2 parts. The first today and the second part 2 weeks from now. Brad Carlson, Extension educator, joins us as always. You'll recognize him. Today, we have Jeff Vetsch joining us. Jeff is a researcher at the Southern Research and Outreach Center in Waseca, Minnesota, and he's a regular on the Nutrient Management podcast.
Jack Wilcox:Brad, let's jump right in where conservation relates to water quality. What can be reasonably achieved?
Brad Carlson:Yeah, Jack. Well, we we spend an awful lot of time talking about, kinda what the what the issues are water quality wise and what's causing them and so forth. You know, we're at a point now where we're starting to to really focus a lot on, what the solutions are. The state's been busy dealing with its nutrient reduction strategy that came out a number of years ago, but it's currently being rewritten. And and, really, that's focusing on what kind of practices are potentially going to make some improvements in water quality.
Brad Carlson:And and I think it's worth noting, all these practices and these changes will, I don't wanna say necessarily equally impact, but but they they both impact surface and groundwater. So in places where we have surface water issues, in places where we have groundwater issues, you know, really the solutions are kind of the same. We tend to have different landscapes in those places, but but a lot of the you know, nitrogen's still nitrogen, you know, and the our crops are still kinda what they are. So a lot of this stuff will pull double duty. You know, I I think the one area that that we we need to really understand is kind of a baseline or foundation of understanding what this whole issue of nitrogen loss in the environment is that a lot of this stuff is coming from natural sources.
Brad Carlson:So there's long term research, done at Waseca and and, the the particular dataset that we use during our Nitrogen Smart presentations has Giles Randall and Jeff Vetsch quoted, from from a journal article from 2011, and we got Jeff here with us today, that looks at some some 4 year totals. And I think the point we we like to emphasize with this is is that when we apply 0 nitrogen or when we grow soybeans for which we apply 0 nitrogen, we're still losing nitrogen through the tile lines. And and if you kinda take some long term averages, it comes out to be about £10 an acre. And so, you know, really, that's the result of our our annual cropping systems. We have crops that that we plant in the spring, and they die in the fall.
Brad Carlson:But we're looking at what's happening year round. And so there's there's big parts of the year where there's no roots or anything else to impede the nitrogen from getting out. And and if you look at that data, even in cases where we're we're applying the, best management practice rates for nitrogen, that loss, it goes up to roughly about 15 pounds an acre, on average. And so, you know, the part of the the whole the whole quandary of this all is if you did a 30% reduction and with meaning like literally not applying nitrogen anymore, it's a 30% reduction. And we're looking at trying to achieve a 45% reduction to meet these surface water quality goals.
Brad Carlson:And so it really kinda tells us that that nitrogen fertilizer management alone isn't going to be the solution to this.
Jeff Vetsch:Yeah. And part of that's related to being a natural system and and nitrogen being in the system from mineralization from organic matter. And the other factor is in our row crop production is that the majority of our drainage comes in the spring after snow melt and after early season rainfall, and there's no crop activity or uptake of n at that time. And that's the period of time when a lot of that loss occurs. So even, the only way you could circumvent that would be a perennial system.
Brad Carlson:Yeah. And and so, I mean, there's been I think there's been a lot, you know, bannered about, not not certainly not in the the farm press because I think that that segment understands. But when you look at some of the the stuff that's been out in the general media, really is demonizing nitrogen fertilizer as the big part of this problem, realistically, that's not that's ultimately, that's not really where the problem lies. And, you know, I'm not I don't wanna sit here and and say, oh, we've got all these problems with corn and soybeans. However, I mean, it is really an artifact of the fact that we're growing annual crops.
Brad Carlson:And so there's there's you know, we're we're looking at needing to do, with those annual crops in rotation, you know, we're going to have to find some solutions beyond, beyond nitrogen management to to address this. If you look at the the kind of the the broad categories of the the practices that have been suggested in the past, There's really, like, 3 big chunks. You know? One is the fertilizer management part, and the next is dealing with landscape and cropping systems, things like cover crops or or changing our crop rotations, potentially looking at incorporating perennials into our cropping systems. And then the last one, that we're we're I guess, we're currently calling edge of field practices.
Brad Carlson:For a long time, we've called it conservation drainage, but we've kinda added some more stuff into it. You know, these are kind of the engineering practices that involve intercepting the water, and doing some treatment on them.
Jeff Vetsch:Yeah. And the the ideal thing is you when you look at these things, there's some that fit really well in certain circumstances, some that maybe aren't gonna fit, in some fields or some areas of the of the, geography of the state and of the Midwest. And then there's some that maybe can when stacked together, could be even more beneficial.
Brad Carlson:And we're we're gonna probably have to combine practices because like we said, you know, we could eliminate nitrogen fertilizer and only get a 30% reduction, not a 45. And so, you know, something else is going to have to happen with that. I think it's kinda worth noting. You know? We're not going to spend a lot of time here talking about, about cover crops and and, edu field practices.
Brad Carlson:We will cover that in detail on some different podcasts. But but, you know, part of the problem with some of that stuff is, it's still a work in progress. You know? That that, some of the the engineering practices are expensive, and the some of the the cover crop and crop rotation stuff, we don't really have the the, the recipe, if you will, on on how to do that and and make it function. If you look at the report that came out in 2013, the, the nitrogen in Minnesota surface waters that the Pollution Control Agency put out, there was a model, an economic model that Bill Lazarus, one of our ag economists, helped develop.
Brad Carlson:And it it looked at the costs of some of these practices and and I think the the thing that and and this is kind of a oh, duh, but it's it's really worth noting that nitrogen fertilizer management is head and shoulders the cheapest thing we can do to address this. Because just simply by its nature, being more efficient with nitrogen as an input, meaning only applying what you need to apply and therefore probably purchasing less of it and then, you know, potentially increasing yields because, you know, maybe you changed your timing or you were using a practice that wasn't desirable. That stuff puts money in your pocket. You know? It it increases yields.
Brad Carlson:It reduces expenses. All the other practices that we employ, cost money. It costs a lot of money to install these edu field engineering practices. Costs a lot of money to it's gonna cost a lot of money, you know, if we're gonna start putting cover crops in all over the place. And, you know, and, of course, some of the issues with that, as I already mentioned that we don't have a lot of the practices worked out, is also going to be varying performant.
Brad Carlson:You know, in particular, like, the the the cost of establishing a cover crop or planting a cover crop in a year that we've got late, an early fall and it gets really cold and then it doesn't ever grow, now you've got an expense that that almost literally didn't even produce any results. And then that that starts looking really expensive.
Jeff Vetsch:And some of these are have big numbers. You know, they don't reduce a lot of nitrogen and they have a bigger, you know, upfront ticket cost. Like you said, the edge of the field practice is that not only do they have a bigger cost, but it's all upfront. And then you gain from it years later, and that upfront cost, if it's not cost shared or some part of a program, that can be a challenge. You have to realize that all these practices and all these things are not suitable on every acre.
Jeff Vetsch:And there's a certain area where it's a great fit, other areas where it's not such a great fit. And that's why stacking things and figuring out where they work and where they don't work is gonna be necessary if we get even close to these goals.
Brad Carlson:Well, that's right, Jeff. And as as, you know, you think about the places in the state where we've got groundwater issues, you know, our sandy soils and then get into the southeast where we've got, lost soils and and shallow, shallow, bedrock and and so forth, and there's not a lot of tile drainage. So, like, a lot of these edgy field practices are designed to intercept tile water and treat it. Well, if you don't have tile water, then there's you can't even use those things and Exactly. You know?
Brad Carlson:So so that's that's also important to remember. You know, the other thing, though, that I like to I like to stress about this is is farmers are fairly keenly aware of what they pay for their nitrogen fertilizer. So if you start thinking about, you know, if you're paying 50¢ a pound or something like that to purchase fertilizer, and now you start looking at these practices that are costing a dollar and a half, $2, $6, a pound to get it back out of the water, it really kinda emphasizes the need to not be applying unnecessary fertilizer. I mean, it goes beyond the fact that being efficient with your fertilizer inputs is profitable for your farming, you know, it kinda then goes past the, you know, my year end tax statement and say, in the long run, if I'm gonna have to also pay to get this back out of the water and it didn't need to be there in the 1st place, it gets really expensive. Yeah.
Brad Carlson:I I'm there was, you know, there's been some evolution in some of this stuff, as far as what it actually costs. Like I said, some of it's a work in progress. I think the cover crop one has really been kind of, difficult to nail down because if you look at just automatically planting cover crops everywhere, I think we recognize that they'll fail in most places, and then it's just a big sunk expense that produces no results. And cover crops don't have to be really expensive if we are strategic about putting them in places where they're likely to succeed, and so that that cost, can be quite variable. And and it's it's very similar to some of these some of these other practices too as far as, being strategic, with with where they go.
Jeff Vetsch:As you mentioned, there's areas where they don't succeed, and there's areas where they you're used as common practice. So those things have to be put into perspective as you develop a plan that's gonna work for an individual field or an individual farm or a or geographic region.
Brad Carlson:Yeah. And the other thing we have to recognize is, and we're sitting here talking about nitrogen, is that some of these practices have other benefits. You know, the one that looks that looks really bad, on on on Bill's analysis was was riparian buffers or buffer strips. But we know that buffer strips aren't really being put in place to prevent nitrogen from getting in the water. I mean, the really the the main benefit you're getting from there is you're taking some cropland out of row crop production, which, of course, you know, then you're putting a a deep rooted perennial in so the loss in that buffer strip itself goes to almost 0.
Brad Carlson:And maybe there's some shallow groundwater that's intercepted. But for the most part, you know, that practice is intended to stop soil erosion and intercept phosphorus. And, you know, similarly with cover crops, you know, we're looking at some of these other soil health improvements that have other benefits also. And so, you know, we do need to be a little careful about not getting all caught up on the cost of these strictly for nitrogen if they do have multiple benefits. The thing, though, that I I really do like to stress to farmers is and this kinda comes off of Bill's analysis in that the PCA document, is he went through and kind of estimated, at least based on what we think is going on as far as changes in nitrogen nitrogen management that could be happening, reducing rates, switching timing, using inhibitors in places where they're appropriate, you know, whatever those those practices might be.
Brad Carlson:And his estimate was that statewide, farmers are leaving $77,000,000 a year on the table, you know, in in terms of either reduced expenses or increased profits. And that's important to recognize. However, when he went into place when and went into the other practices and started estimating what they cost, you know, and and maybe I should mention that his estimate, at least from some some of this stuff and Dave Mueller worked with him on some of these, these reductions, was that we almost got to a 15% reduction if we did everything everywhere we could nitrogen management wise. But then if we turn around and we start putting in these edu field practices, these drainage, related things, he was estimating a $74,000,000 cost, statewide for that. And that again, that's an annual cost.
Brad Carlson:So basically, you're taking all your savings from nitrogen management and you're turning it back out and paying it back out in the expense of putting in these edu fuel prices. That didn't quite get us to 20%. So then when we start looking at some of the vegetation changes, which includes things like like literally taking sensitive land out of production, which that takes your profit from whatever your profit is and turns it to 0 because you're not growing crops there anymore and so forth, That stuff got exceedingly expensive. I mean, the the number Bill came up with was $1,400,000,000 a year. I mean, that's that's just a crazy number and and it but it's and it was per year.
Brad Carlson:I mean, that that wasn't a one time expense. You know, I guess, really, the the the take home message is not so much to dwell on those numbers, but really to to look at the nitrogen management side of this and say as an industry, like, this is so far and away the easiest thing we can do to address this problem. Everything else gets exceptionally expensive after that point.
Jeff Vetsch:Yeah. And what I would add is that, you know, the cost savings and the of the nitrogen management practices, you know, can get us 13, 14 percent reduction. And and that's not only, you know, something that can be done fairly easily, but it can be done on a large number of acres. Where you look at the tile drainage BMPs, as we mentioned before, and you've got a lot fewer acres across the corn belt that you're going to be able to implement those types of practices on. So even though the percent reduction is smaller, it's because you have a lot fewer acres that you can use them in.
Jeff Vetsch:The other thing that I would add though, when we look at fertilizer management optimization, the biggest challenge with that is the weather, you know, and that does throw a curveball and it didn't for a lot of growers this spring in particular in south central Minnesota and Northern Iowa. So it does take extra management even though we perceive it as kind of a no brainer. You can make more money and you're gonna get this benefit not only agronomically, but also environmentally. It takes very detailed management to to deal with these things as you have weather that makes it challenging and increases nitrogen losses. Or if you're coming off a couple drought years and you think you got carryover in out there.
Brad Carlson:Yeah. It really kinda comes back to the the whole, the whole, premise of nitrogen smart, and that is to understand how nitrogen is behaving and then also understand the dynamics of your production system, your field, your soils, the weather, and then make the best management decisions as you go along. It's very it's a very difficult thing for a lot of farmers, particularly if you get to a certain size because you you really want to or need to streamline your operations to be efficient. However, you know, from a pragmatic standpoint, I mean, we would the ideal would be to be adapting your management on an annual basis to to kinda match what's what's given you. And even that doesn't work, Jeff, because, you know, we look at last a year ago, and the the fall of of, 2023 was dry.
Brad Carlson:And we were saying, well, if there's ever a good year to put on fall nitrogen, this is it because we got this big water deficit. The odds of losing this nitrogen aren't really high, and then it got unbelievably wet in the early summer of 2024, and lo and behold, we did lose most of that nitrogen. So even then, you know, we don't have the crystal ball to to figure this out.
Jeff Vetsch:What is ironic, though, is when we look at the the green part, the vegetative changes, is they're kinda weatherproof. That cropping system change usually is works no matter what the weather is. Right. And that is that is a key factor to think of even though economically from a land use, you know, return on investment. It's a dramatic change, but it does work dependent no matter what the weather.
Brad Carlson:It does. And and, you know, this is this is a long term solution if we're starting to look at that. I mean, there's been some people who have bandied about the idea of like, well, we need to just retire sensitive land or so forth. I mean, I did the math and this is actually part of one of our different advanced nitrogen smart presentations. But if we were going to if we were going to achieve water quality goals strictly on the basis of either land retirement, like putting into CRP, or having a perennial crop on that land, I mean, we would have to devote literally 1 third of our cropland in Minnesota. I mean, that that's just not that's just not a a solution either.
Brad Carlson:And so it's just it's going to have to be something comprehensive. Let's change gears a little, Jeff, and I wanna talk particularly about some stuff that that you've had your fingers in over the over the years and and that's, kind of going then over to the side of of the nitrogen management stuff and and some of the technologies and the tools that have been out there to try and help advise us or be very precise or or even site specific variable rate and so forth within a field. Really, there's there's 3 major kinda categories the way I see it of of this kind of technology. We've got the sensor stuff that's looking at the crop. There's models that are intended to predict what's happening out there in your field and the environment, and then we've got the some testing technology.
Jeff Vetsch:Yeah. I think that the sensors have been around for quite a while. I mean, probably going on over 20 years now or more. The in season testing, I I you know, I think that's where we're gonna see some changes because I think you're gonna see sensors move more into in season testing and having sensors maybe that test in the soil or sensors that test using different techniques than we've had in the past.
Brad Carlson:Yeah. You know, some of this, this is really high technology because, you know, there's really you know, if if you really get down into the nitty gritty of it, you know, there's there's really only a few things that can be measured, you know, like electricity can be measured. And so if you're looking at passing some electrical pulse and seeing some change in that, light can be measured and so you're passing a light beam through something, you're measuring differences in the light beam. You know, a lot of this gets back to what can we actually measure or sense as we're literally going through the field, and, then how do we interpret that? And and one of the the big issues historically has been interference with the signal you're looking for. And I know, like, for instance, you know, one of the one of the big problems, and this is, again, this is getting way into the weeds, but one of the big problems with sensing nitrate in water, has, in on real time basis, has always been the fact that when when when it's when you pass light through it and you're you're looking at at absorption of different, chemicals based on what they absorb in the light spectrum, nitrate is the same as bromide and so which is just totally unrelated, you know, but but the problem is then if you wanna get a nitrate number, you've gotta also calculate bromide, which is not important to anybody, but you need that number so you can subtract it off the top to get nitrate and and some of this stuff gets really complicated in that way.
Jeff Vetsch:Yeah. And the the active and passive sensors, I mean, they work best when the crop starts telling a good story. The challenge is is in that timing of how fast you can turn around and make that application is the limiting factor, and that's that's where it gets, that's where it gets difficult.
Brad Carlson:Yeah. I know you've worked a lot with the active sensors. I think the one most people are familiar with is GreenSeeker, but there's been a lot of these products that have been out there for for quite a long time. They, you know, they seem good because technically, you could mount one of these things on the front of an applicator and you could be reading the crop condition on the front and applying fertilizer right out the back as you're driving across the field. And so they they are relatively timely, and they, they can be relatively inexpensive.
Brad Carlson:You buy that thing right up front. I mean, assuming you've already got a a fertilizer spreader and it's got the ability to adjust its rate on the fly, you know, you're not talking about a great expense of a of a unit there. But, you know, the problem we've had a long time with sensors is when we see a change in the crop canopy, for instance, with your own eyes and when it turns yellow, did you already lose yield? You know? And so is it too late?
Brad Carlson:And and and then in addition to that, you know, how do we calibrate? You can see that it's yellow, but what does that actually mean with respect to how much nitrogen you need to apply?
Jeff Vetsch:Yeah. You know, developing the algorithm or the the, you know, the the recommendation is the challenging part and it and it can be affected by, genetics. Crop genetics can change it to soil. You know, separating the color of the soil or the background color with the crop color is a challenge. And, actually, they've developed some really interesting software that does that, but these are all things that hurdles that they have to to get over.
Jeff Vetsch:And, you know, on your last con is the application may be too late. That's the challenging part part. And take a spring like this spring, and if you were gonna delay a lot of your end management this spring until, mid to late side dress, say, v 8 to v 12, we had extraordinarily saturated fields at that time that were almost impassable with conventional ground equipment. How would we have ever gotten significant amount of nitrogen fertilizer on those fields? And then the risk that you take on by delaying that application and relying on that, you know, entire or a very high percentage of your n is applied at sidedress versus upfront.
Jeff Vetsch:That's that's taking on a lot of risk as a grower, especially on poorly drained soils.
Brad Carlson:Yeah. And, you know, you mentioned crop genetics and, you know, that's that's another thing I think is worth talking about that, you know, for one thing, some of these, products have been used successfully in other crops. They've been used in small grains, winter wheat, I think, particularly, in southern areas. And so, you know, there's been the want, like, well, if it can work there, why can't it work elsewhere? But there's also been things relative to long season corn hybrids like we don't grow up north.
Brad Carlson:You know, 115 to 120 day and longer corn hybrids have a longer window to avoid sensitivity to loss. I mean, when we're dealing with a 95 day hybrid in Minnesota, you know, the the time period that passes by where all of a sudden you've lost yield is very short. And and and so, you know, that that's been really problematic for us.
Jeff Vetsch:But I think the places where they can work in in Minnesota Ag or the upper Midwest is certainly on we've got a lot of irrigated acres. I mean, they they have a fit there because you're you have the ability to put fertilizer on and water it in and make sure it becomes active right away. They can work in that environment and then as a rescue treatment. And, obviously, this spring was a year when we had a ton of fields that needed a rescue treatment. And we've seen that the genetics are changing a little bit and more of the n is taken up in new corn genetics after flowering than it used to be.
Jeff Vetsch:So there's probably still reasons to go out there and do some of these later midseason before just before tasseling rescues than we would have probably recommended in the past, especially if we think we can get some moisture to help get them incorporated into the plant.
Brad Carlson:And, you know, it's worth it's worth noting, Jeff, that that that's a viable use of this technology. However, it's not nitrogen management. It's it's being reactive to a to an environmental problem. You know? We we aren't we we we hope to never go into the season saying, well, what are we gonna do for a rescue treatment this year?
Brad Carlson:Because if you're dealing with a rescue treatment on an annual basis, you probably got some long term problems with with your with your farm. You know, the other thing about it is, you know, we've talked and we already had talked about this a little bit when we talked about the loss of nitrogen even when we apply 0 fertilizer and the fact that that's coming from, how much nitrogen's come being mineralized in the organic matter of our soils is, you know, we do have the ability in Minnesota to supply a lot of nitrogen from the middle of the growing season on, particularly provided it's not all saturated if we get decently warm days and sunshine and so forth. And so in some cases, you can pick up these these yellow colors, and it truly is a nitrogen deficiency. However, you don't get a response to the fertilizer applied because that's the time of year the soil kicks in and starts supplying it anyway, and so it didn't really matter.
Jack Wilcox:Extension educator Brad Carlson, and researcher Jeff Vetsch. Thank you for talking with us at the Southern Research and Outreach Center in Waseca. We'll pick up the discussion again in 2 weeks.
Jack Wilcox:Do you have a question about something on your farm? So 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.
