Nitrogen BMPs and nitrate water quality issues in southeast Minnesota: What should growers be thinking about?
Hello, and welcome back to University of Minnesota Extension's nutrient management podcast. I'm Jack Wilcox in communications with Extension.
Jack Wilcox:Today, we're talking in-depth about Southeast Minnesota nitrogen BMPs and nitrate water quality issues. We have five educators, specialists, practitioners here with us today. Can you each introduce yourselves?
Mary Nesberg:Yeah. I'm Mary Nessberg, and I'm an extension educator here in Olmsted County for agriculture and horticulture.
Daniel Kaiser:I'm Daniel Kaiser. I'm a nutrient management specialist with the University of Minnesota. I'm located at the Saint Paul campus.
Brad Carlson:Brad Carlson, extension educator. Work out of the regional office in Mankato, but statewide issues related to water quality and fertilizer nitrogen management.
Kevin Kuehner:My name is Kevin Kuehner, and I'm a hydrologist with the Minnesota Department of Agriculture based here in the Southeast in Preston.
Jeff Vetsch:Hi. I'm Jeff Vetsch. I'm a research supervisor with the University of Minnesota Southern Research and Outreach Center based in Waseca, Minnesota.
Jack Wilcox:Brad, let's start with you. What's the current situation with nitrates and water quality in Southeast Minnesota, and are conditions improving over time?
Brad Carlson:Well, there's actually kind of a dual track with that. In an overarching sense, we've been dealing with the goal, it's been quasi national, of a reduction of the amount of nitrogen flowing down the Mississippi River 45%. That's to address hypoxia in The Gulf. That's been ongoing for a long time. So as such, Southeast Minnesota has been part of the state's plan for quite a long time.
Brad Carlson:But of course, we know because of the soils and the conditions in Southeast Minnesota, groundwater and surface water are closely linked. You know, there's been issues with groundwater in Southeast Minnesota going back quite a long time. However, there's really not a really good data set if you went back say pre 1980 that kind of documents how bad the problem was or how extensive the problem was. It really wasn't until some of the local counties started pooling their water testing data in the early 1980s that we actually had a kind of a bigger picture of it. But regardless of that, there's been a lot more focus lately.
Brad Carlson:There's been some concerned groups and citizens and so forth who've kind of expressed concerns about the high nitrates in water wells, private wells. If you look at the presence of those, where they are in the Southeast, they kind of follow the the ridge where a lot of the bluffs are. When you get closer to the Mississippi River, a lot of that land isn't even cropped, and so we don't see a lot of problems over there. And then when you get kind of higher up on the plateau, we don't see quite so many problems either. But there are sporadic wells that have high nitrates throughout the Southeast.
Brad Carlson:And, of course, the federal drinking water standard at 10 parts per million is, you know, is to be taken seriously. You know. So from that standpoint, if somebody's got high nitrates, you know, they should be looking at at some kind of a a plan to get better water, whether they drill a new well or install reverse osmosis or go to drinking bottled water or whatever that might be. And, you know, the the extent to that really kind of varies across the Southeast. I don't have the exact numbers, and I don't know that we ever really will know exactly how many wells suffer from high nitrates, but it's a significant enough number that that we're purposely addressing the issue and Kevin can talk a little bit more about, know, some of the is it getting better because that really has a lot to do with, you know, when when that water that that you're pulling out of that well, when it was up on the surface and and interacting with with nitrogen up on the surface.
Kevin Kuehner:Yeah. I guess to to add to Brad, I think you kinda set that up pretty well. You know, to to get at this question of the nitrate issue in Southeast, we have to kinda think about the geology, right, and how that water moves through these different layers of rock that we have here in this area. And, this area is is, unique in terms of this part of the state. We have a landscape called karst, and karst is, you know, kind of the key features that we have in karst are disappearing streams, sinkholes, caves, and springs.
Kevin Kuehner:And the reason why we have that is because of this, kind of very slow but steady process that occurs over thousands to millions of years, which is a chemical reaction with the limestone that we have here in the Southeast that slowly dissolves away some of that rock over time that creates the features that we have. So to understand nitrate, we have to understand how groundwater moves through those different layers of rock, And, you know, we I think the this area, of course, gets a lot of attention that we know that that water can move very quickly from the land surface to subsurface groundwater. But at the same time, it can move very quickly, but also what's kind of overlooked a little bit, and this is what this is important to understand this, in terms of understanding of how this water moves in our in our nitrates getting better or getting getting worse, is that, in embedded between these different layers of rock, we have what are called, confining layers or or what geologists call aquitards. And these are areas that basically inhibit the downward movement of water and slow that water up considerably. And in many cases, that water will actually travel instead of, you know, down, it will actually move it sideways.
Kevin Kuehner:And, that sort of expresses itself in our springs, for instance, that eventually feed our our streams here in the Southeast. So you can imagine if you have a well, let's say a well that's, constructed and you have a 150 feet deep, and you're above one of these confining layers, your well water is gonna be much different than a well that could be right next to that same well that is deeper, let's say, hundred, five hundred feet deep that is below one of these confining layers. And, what we typically find is if your well is properly constructed, wells that are below these confining layers, have either no detectable nitrate or very, very low nitrate. If now if you're above one of these unconfined, sort of aquitards or confining layers, the nitrate levels typically, what we see, and this is thousands of data that we've we've analyzed over the years, is that the nitrates are typically the median concentration, would be about four milligrams per liter. So half would be above that level, and half would be potentially lower than that.
Kevin Kuehner:But it's not uncommon also in those shallow, surficial aquifers to see nitrate values above 10 milligrams per liter. And we can see, and again, it depends on the data sets, but we can see between 10 to 20% of those samples that may exceed the drinking water standard. So to really get at this question of nitrate, you gotta understand, yeah, the geology and how groundwater moves. Kind of the three really big factors that affect nitrate would be land use surrounding that well. So what percentage of that land area is, let's say, forest land versus grassland versus row cropping?
Kevin Kuehner:Another kind of key factor is, again, like I said, mentioned the geology and how that water moves, different rock layers that it goes through, how much soil is above that rock. And then, the third one would be, well construction. That's another be another key component. And like I mentioned, so well construction, really how that kinda plays in is if your well was constructed before 1975, that can be much different than a well that's constructed after 1975. And the reason for that is because Minnesota has a well code, and they require when you drill a well, anything, starting in after 1975, it's required that it has to meet certain requirements, similar to electrical or plumbing code.
Kevin Kuehner:And really the the heart of that is to make sure you have adequate casing and you actually have grout also in those wells. And that prevents some of that younger water that could be picking up contaminants from getting into your well water. So wells are purposely constructed, you know, to avoid some of that recent contamination. So that's a a really big determinant of what you might see in terms of nitrate in in your in your drinking water, those kind of those three main areas.
Brad Carlson:And and, you know, I think the perception has been for a long time that the travel from the surface into water in Southeast Minnesota is almost instantaneous. Like, what's up there today is coming out of the hill tomorrow, and that may be the case in in the case of, like, sinkholes and and a few special locations. I know there was some research done in the forties involving some some waste discharge and it being picked up in wells within three days and so forth. But Kevin, a lot of your work is showing that that's not that's not typical of most places, you know, and so that's really important if we talk about our conditions improving over time, we do have to kind of a feel for just when that water was on the top and now when when it's coming out of the well.
Kevin Kuehner:Yeah. So this has been a long asked question. Right? Is is the water quality getting better? Is it getting worse?
Kevin Kuehner:Especially here in the Southeast. And frankly, across the entire state, you know, as as with our clean water fund dollars, or is that making a difference? And to answer that question, especially with regard to, you know, is it having an impact on the groundwater? That's a very complex question and and how to deal with it. We know at a plot scale, at a research plot scale, it can be difficult to answer some of those questions sometimes because of variability and all those things that are happening.
Kevin Kuehner:But, what we did is is, because it's so complex, know, we we recognize that it's you gotta have multiple, like, a team effort to answer that question. People that understand soils, also understand agronomy, but also people that understand the geology and how that water moves in the system. Probably back about ten years ago, I remember getting a question from a farmer asking that same question, like, hey, is it getting better? Is it getting worse? And is is are the practices that I'm doing today, is that showing up, you know, in the water?
Kevin Kuehner:And, you know, it's one of those questions that you kinda think about, and you're like, god, that's a tough one to answer. You we just don't have the the science right now to answer that. But really, it wasn't until the last five years that we kinda came together. It was a variety of different scientists and researchers came together to get at this, tackle this question. Is number one, what are the nitrates doing today?
Kevin Kuehner:What are the trends? And then number two is how do we interpret those trends? Right? So what we did is we did a really thorough analysis of all the available data that we could get, looking at both well data, stream data, and spring data. We analyzed the trends of that data.
Kevin Kuehner:So out of like, I think it was like 24,000 different sites that we had, it ended up being about 1,200 sites that we had enough data that we could run this statistical analysis on that. And what we found was that if we look at well data, and this is data going back, basically about the last twenty to twenty five years, so around around 2,000 through current, roughly, we find that, about, 30% of those wells have no detectable nitrate. Another 50% have no trend, so there's no it's not going up, it's not going down, it's just kind of holding steady. We have about 4% of those wells that are decreasing, and we have about 13% that are increasing. And again, that's a data set of about 1,200 or so roughly, roughly wells.
Kevin Kuehner:When we look at spring data, spring, these are groundwater that's emanating, that's where groundwater becomes surface water right before your eyes. When we look at spring data, and stream data, we find much different story. We find that over 50% of our springs and stream data are showing an increasing trend. And that's not only consistent in Southeast Minnesota. We also looked at a data set in Northeast Iowa.
Kevin Kuehner:Very similar geology, similar soils, and land use, and we find a very similar story with that data. So it's telling us that this is sort of kind of a region wide sort of thing that's going on. So ultimately, it's one thing to do all these trends, but then it's like, well, how do we interpret what's what's causing this, right? So one of the things that we've kind of long sought after and we thought about is that we think that some of this can be explained by the age of the water, kinda getting back to Brad's point. And the age of the water, what we what we, I guess, define as hydrologists is we call it residence time.
Kevin Kuehner:And residence time can be really kind of easily kind of explained as being the amount of time it takes for rainwater or snow melt to infiltrate the land surface, make its way through the soil, through the bedrock layers, and eventually come out to whatever you're monitoring, whether it be a well, a spring, or a stream. And so we're trying to we have to figure we're trying to figure out a way to quantify that amount of of that relative age of that water. So we worked together on that. We used a variety of different methods to do that. One of them was using chemical tracers, using products that have no longer been used today.
Kevin Kuehner:One of them being Alaclor, the trade name Lasso. That was a commonly used herbicide product in the seventies and eighties. Usage immediately sort of really quickly declined in in the late nineties and early two thousands. We used that as a tracer to estimate the age of the water. We used other methods along with our other partners to do that.
Kevin Kuehner:What we found in the terms of the results is we found that the age of the water ranged in many of these springs that we kinda really, really focusing on. The age of that water ranged from between about ten years up to about forty years. So we're talking, you know, decade old type time scales in terms of the age of that water. Now one thing I wanna mention is that when we take that sample of water, you know, really that water represents a mixture of ages. Right?
Kevin Kuehner:Some of it could be younger. Some of it could be older. Like Brad said, some of that water's gonna move gonna move quickly. Some of it is gonna move much more slowly. That water that's stored within all the pore spaces of the rock, for instance.
Kevin Kuehner:Now when we look at well data, we tend to find that water is a bit older. Right? Because that makes sense because we intentionally design and construct wells to avoid some of that recent water. Right? So we can find that well water could be, you know, well water could be upwards of 50 to 80 years old, you know, in in many cases.
Kevin Kuehner:There's also another component, and this is this really old water. As I mentioned before with the with the well trends, is that we found about a third of the wells have no detectable nitrate. So what's causing that? When we look at that subset of data for those wells, we find that that well water is thousands of years old. And it ends up being an average age of about 7,000 years old, is what the age of that water is.
Kevin Kuehner:So when you when you kinda pull all that data together and all that information together, that sort of helps you provide insight of how do we start to interpret this. And what we found was that there's a linkage between the age of the water and the trends that we see. And what we tend to find is we see this kind of direct relationship between the age of the water being if you have older water, we tend to find a higher probability that you may see an increasing trend. Where if you have younger water, let's say let's let's say let's say less than 20 years old, the the more likely scenario is that the age of that water would be, you know, less than 20, but we tend to find no trend or in in in some instances, a decreasing trend. So our interpretations there is that that could be a result of improvements.
Kevin Kuehner:Right? Improvements that we as landowners and farmers are doing to help reduce that. The problem is it's hard for us to discern that. Right? Right?
Kevin Kuehner:And accurately kinda tease that out. And actually, what we think is probably the more dominant factor there is probably the variability and the noise that we're getting from the weather and the precipitation data. And especially the last twenty years, we've been very wet, and so that really wet conditions can cause a dilution effect and actually kind of dilute some of that that nitrate that we see in those shallow, surficial aquifers. But the deeper aquifers, again, we tend to find, in many of the systems, it's decadal sort of ages, and so it's much older, and we tend to find, not always, but especially for springs and streams, we find more of an increasing trend, and for, you know, certain percentage of those wells, we'll also see some increase in as well in those sites, again, kind of related to the age of the water.
Jack Wilcox:What should growers in the region be thinking about in terms of nitrogen best management practices?
Daniel Kaiser:Well, one of the things that we look at with some of our BMPs is really more of a timing component because that's, I think, the main thing with the karst is just the speed at which the water can move through that soil and carry nitrate with it, being that the soils themselves are highly or more permeable. They're not like a sand in that some circumstances, but still the silt loams that dominate these areas. The silts tend to have be very permeable that there is a lot more risk. So that's why if you look at our best management practices, they're really geared towards spring application at a minimum just to try to limit some of the issues. Fall applications in these areas, I mean, the challenge is, you know, being silts, these soils have a lower cation exchange capacity, which speaks to the ability of the soils to hold positively charged ions, ammonium being one of them, which isn't typically our fertilizer source for fall applications, so we really can't hold that.
Daniel Kaiser:And then these areas are warmer too. I mean, if you look at the gradient in Minnesota going from the Southeast to the Northwest, there's a temperature gradient and also a precipitation gradient. So there's much greater risk when it comes to leaching or or lost potential movement of water through the profile in these particular areas. So spring really has been the key when it comes to a lot of these things for applications. I mean, certainly, I think we could talk a little at some point here on split applications.
Daniel Kaiser:You know, there's many growers that have looked at more directed applications in season in some of these areas. But, one of the other questions that we've had one of the other questions that we've had in these areas has really been looking at the rates themselves, and that's one of the things historically with a lot of our research and a lot of if you look at go into some of our fertilizer guidelines for many crops, the Southeast, the silt loams, even though they tend to be lower organic matter, the mineralization potential in these soils or the release of nitrogen from the organic matter being broken down in the soil tends to be higher. And, well, I think that a lot of that speaks to the fact these soils, you know, tend to hold ample amount of water and well aerated, two things that that many of the microbes need, that historically that we've been suggesting less nitrogen in these areas. Currently, our guidelines aren't split, but I'm thinking here moving forward that we've got enough data really to start looking at that, that maybe these areas, compared to, say, Central Minnesota, the Southwestern Minnesota where we have higher clay soils with more potential for denitrification that they need a little less.
Daniel Kaiser:And, you know, when I've looked at this, I've been working with the nitrogen guidelines since around 2015 here in Minnesota. And when I looked at the data, we really couldn't see a lot of separation, but we're starting to see with the the trials more directed into these areas, some consistency where, know, you maybe takes a little less nitrogen in these areas, not as much as you might think. What I'd recommend a lot of growers at this point look at is if you look at our maximum return to nitrogen or the MRTN system is looking at maybe towards the lower end of the ranges with some of the recommendations because that's where it tends to kind of fall out. So there might be some things there with it. You know, the big thing really for these areas, I think timing kinda is the more critical thing because it you can't hold the the ammonium or if it converts quickly, they're just much greater risk.
Daniel Kaiser:And when you start talking about shallow topsoils, I mean, you do it can be pretty quick. You know, know Jeff, Brad, you look at some of these soils here. I mean, the depth, the bedrock in some of these is pretty shallow, so there's a lot of risk.
Brad Carlson:Yeah. I know in even like in in Eastern Rice County, and I'm I'm familiar with some fields where we had less than two feet. You couldn't, know, you're trying to take a two foot soil sample and you're hitting rock, and it was limestone. So, you know, it's it's that that that that occurs sporadically throughout the Southeast. Dan, can you say a little bit about the about phosphorus fertilizers and and MAP and DAP?
Daniel Kaiser:So that's a great question, Brad. When it comes to fall application with it's it's the same issue with sources because I said, if you look at anhydrous ammonia, you look at MAP or daperture, monoammonium phosphate or n h four. There's a little difference in anhydrous that can affect the soil biology, and that's why we tend to recommend fall application because it can slow down the conversion. But the ammonium itself isn't leachable, but it can be converted relatively quickly. So one of the questions that we've had in the research side for I I think this has been looked at somewhat.
Daniel Kaiser:I mean, Jeff, I think, was involved, and Giles Randall was was still was not retired at that point, working at some studies for fall application on, you know, just the general question of what availability we get from that. Because all of our phosphate fertilizers that are out there, that are easily available, I know we see triple super phosphate, which is o 46 o. At some points, it's it's in the market here and there, but, in general, it's always ammoniated phosphates. And that's the trick on that is that we don't really know what kind of availability we get, or at least what kind of conversion we get in the fall from those applications. And I think a general rule of thumb is the earlier you go, I mean, the more risk you have essentially for that to convert to nitrate than ammonium.
Daniel Kaiser:And, you know, if we the soil stay warmer later in the season, if they don't get below 50, you're gonna see a a sheer just a a large amount of that being converted. And it's just there's no good rule...
Brad Carlson:Converted and lost.
Daniel Kaiser:Converted and lost, and there's really no good rule of thumb at this point. So that's kind of the problem we have is I I'd almost rather see some of these areas that are more at risk carry something like a triple, because I think you you look at it, but most of the growers aren't really factoring a lot of that fall applied in in in those in those sources. So it's a question of why it needs to actually be there because it's just at a higher risk for loss. So, I mean, that's one of the things, you know, I would maybe look at just to prevent some of that if you're trying to take really, right now, with with fertilizer prices high at the point when we're recording this, just trying to take advantage of many of those nutrients as you can, and so that the only really way to do that is to focus more on the spring application.
Jack Wilcox:Jeff, what about split applying? Is that worth the is that worth the cost? What what about water quality benefits with split applying?
Jeff Vetsch:Yeah. I think the data that we have over the last ten or eleven years here in Southeast Minnesota, we've looked at split application pretty closely on on farm sites with full end recommendations, so we also get an idea of what the optimum in rate is. And in the older data from 2015 to 2021, we had a yield advantage for split application about 20% of the time on the silt loam loss soils in Southeast. Generally, it was not a large yield advantage. It usually ranged from four to 10 bushels, and of course, it does involve some extra time, effort, and labor on the farmer's part.
Jeff Vetsch:And when you think of some of the smaller fields when you get into Houston and Winona County, they can be challenging to side dress supply. You end up driving down a lot of crop side dressing in some of those small fields. Our more recent data, over the last four years, we've had the advantage of using a regression analysis because we have full N rate curves for both pre plant and split applied N, and in that data, three out of the 16 sites, or about 20% again, had a significant yield response, but when we look at it from a regression standpoint, it goes to about eight out of 16 sites that either had a yield advantage or required less N when split applied. And I think that's where, if that can be consistent, that seems like it's worth pursuing some of those advantages for split application on fields. Interestingly, when we think about when the N rates are calculated, there really aren't big differences in the residual soil nitrate, so that's kind of our water quality parameter.
Jeff Vetsch:As long as we're clear near the optimum, we don't really see differences in that amount of carryover N. Now, we get higher N rates above the optimum in years when maybe we didn't need as much, then there tends to be a little bit more carryover residual soil nitrate with split application compared to pre plant, but it's not a large difference. The other thing that I would mention that I think is important is in the dataset that I've collected over the last five years, split application is generally reduced the year to year or field to field variability in the economic optimum rate at these sites. And I think that is probably as important as anything because if you can minimize the risk of these adverse weather years by doing split application and narrow that window of what that optimum rate is, that can be a pretty important tool, not only in agronomic side, but also on the environmental side. Especially with fertilizer prices as high as they are.
Jeff Vetsch:Right, Brad?
Brad Carlson:Yeah. So, you know, understanding how to be dealing with some of the challenging economic stuff with respect to fertilizer management, it's important to recognize that we've kind of been doing that with our nitrogen recommendations for a long time. We use the MRTN method. The M stands for maximum. Sometimes people use the word marginal.
Brad Carlson:It's not marginal. It's maximum. And and the way this works is if you grow some corn and you apply zero nitrogen, you're going to get some kind of a yield, and that yield is corresponding to the amount of nitrogen that's supplied by the soils on-site. And if you add some nitrogen, the yield is gonna increase. You add more nitrogen, the yield is gonna increase, but at some point you're gonna maximize yield.
Brad Carlson:You can't just keep fertilizing and let your corn yield go out of sight. It doesn't happen. So we call that the plateau goes up and then it levels off. Obviously, every pound of nitrogen you buy, that's just a linear cost. Each pound has whatever 60¢ right now.
Brad Carlson:It just goes up in a straight line. So if you combine that cost straight line with the curve, the plateau of response to that nitrogen, you turn that into the profitability. And so what you see is as long as it's returning yield, it's gonna keep going up. But once it's no longer turning returning yield, the extra cost takes over and that curve starts going back down again. So it reaches a crescendo point, and that's where the MRTN is.
Brad Carlson:And so if you look at the rate recommendations for us, it's always a window. So it's twenty, thirty pounds between a lower number and a higher number. That window is actually plus or minus a dollar. I mean, that's that's really not very sensitive. If you think about that, that's less than a half a bushel of corn, and it's almost impossible to even be that accurate with measuring out in the field.
Brad Carlson:And a lot of people stress out about that extra twenty, thirty pounds in there, but in reality, it's just returning dollar for dollar with corn, and it's not that big of a yield increase. You know, when we're talking about a half a bushel being a dollar, It's not even a half a bushel, of course. And and so that flexes based on the price of corn and the price fertilizer. Everybody knows the price of corn right now is lousy. What I've heard this week, I guess depending on when you want to take a price, you know, at the the ethanol plant close to me was $4.12, but delivery in the spring was $4.20.
Brad Carlson:So if you wanna look at determining what your price ratio is of the price of corn to the price of nitrogen fertilizer, you know, I guess we'll pick pick which one you want. You know, probably at the time you're buying the nitrogen and putting on or paying for the nitrous is maybe the price you wanna take. But anyway, with $4.20 corn and the current price of nitrogen is about 60¢ a pound and and remarkably close similar between urea and anhydrous right now. There's only 2¢ a pound different between them at about 60¢. So you're dealing with a price ratio of point one five.
Brad Carlson:And so because that price ratio is not advantageous, it's actually lowered the profitability of applying nitrogen. So we would see our corn on corn or corn on soybean recommendations actually, which normally would be at the point one price ratio, which is where typically we see nitrogen price. That's maybe 150 or 155 depending on kind of what you want to look at. But currently at the point one five price ratio it drops it down to 135 you know so you know you're looking at 15 pounds an acre you know so you know multiply that times 60¢ and then across your acres and you can have a fairly significant dollar savings on that. I think it's important to recognize too that the MRTN methodology is encompassing most of the sites.
Brad Carlson:We use a mathematical process called the quadratic plateau, and so it's actually encompassing the majority of our research. It's not a fifty fifty. It's not a situation where half of it needed more, you know, then it's just a coin flip. Is that the right rate or not? It's the majority of the situations that are encompassed by that.
Brad Carlson:And we've kind of found that actually the the sites that require higher than recommended rates tend to be kind of predictable. And so I know, Jeff, you've done some work where you've actually been able to kind of isolate that.
Jeff Vetsch:Yeah. We have one site in Eastern Mauer County with our long term study, Kevin, we've been there for seven or eight years now, I believe, on that site, and it's a loess cap soil on top of some old glacial till, and it's a poorly drained soil, and even though it's not truly in Southeast Minnesota, it's just within a few miles of Fillmore County, and that site in particular acts more like South Central Minnesota, and it like like what we would get a real response to nitrogen at in Waseca, and it takes a little bit more in. And I think it's been consistent enough that I would feel comfortable making a recommendation there to be on the high end of the recommended or acceptable range, and maybe even a little bit more than that in some years. And, unfortunately, that site also has had a couple years when it needed a lot of N, and when it was a very difficult, high loss end situation. The good news is that site has also generally responded quite well to split applications.
Jeff Vetsch:So maybe once you get that knowledge at those locations and you use those tools in your BMP tool bag, that can be an advantage and help minimize not only the growers' risk and the agronomic risk, but also the water quality risk.
Daniel Kaiser:And I think that's a key point, what you just brought up, Jeff, because when we start talking about best management practices or BMPs, you start talking about things like the four r's, which is rate, source, timing, and placement that we most of the time, we focus on rate with a lot of this stuff, and we try to manage ourselves out of some of these issues with rate when maybe we should be looking at one of these other r's, because that's really, I think, the key in especially in some of these these challenging regions of the state is just that, is that, you know, we need to be looking at all of the tools and to see if there's any better options. And then Brad brought something up too that was interesting is when we start talking about these BMP regions in the state of Minnesota is that we do have them separated down to the county lines, but that doesn't mean that the soils stay at those county lines. So and then I know Eastern Rice County, you've got some limestone outcrops in those areas that some of those soils should be treated like the Southeast.
Daniel Kaiser:The another good example of that is the far southwest part of Minnesota where there are some soils there that really should probably be more like the the Southeast. So, I mean, it it's challenging, I mean, when it comes to this, and that's why, you know, for us researchers, I mean, we'd like to give everybody just the the straight answer of this is what you should do, but there's a lot of variability out there. You know, farm situations, what they're dealing with with sources on their soils, that it becomes somewhat challenging, that we just have to give you a good starting point, and then start looking at the tools and what you know about how nitrogen behaves in the environment to figure out then what to do beyond that.
Jack Wilcox:And while we're talking about the MRTN, I wanna point people to cornnratecalc.org. If you are interested in finding your maximum return to nitrogen, there's a a calculator you can plug in rates.
Brad Carlson:You could plug in the rate and the corn price. I think it's better if you just select the option to say multiple multiple what is it called? Multiple prices, I think it says. Right. Well, multiple prices, and then it just gives you the different ratios.
Brad Carlson:Because, I mean, ultimately, it's very difficult to determine exactly what your corn price is because farmers are contracting corn, and they're somewhat spot delivered. Some of it's contracted. Some of it's not marketed at all. It's sitting in the grain bin. So it's hard to know exactly what your corn price is.
Brad Carlson:You know, so, you know, it's easier just to kinda take a ballpark anyway. So just I I like to do the multiple rates and then look at the multiple ratios.
Daniel Kaiser:And most of the time, it should be around a point one price ratio. That's what historically the everything's been at. But with the way prices are at kinda when we're recording this, it's been a situation where we're at closer, like, you said-
Brad Carlson:Point 1.15 it is now, and I think that's almost historically high. I don't we've we've rarely gone higher than that.
Daniel Kaiser:And, you know, just one thing before we move on. Do wanna bring up Brad, you know, talked about marginal you know, that's not marginal return to nitrogen, but we do look at essentially the marginal return, which essentially is the return per unit and applied. And we're not with the MRTN approach focused on maximum yield potential of it mean because nitrogen's only one point in that. So we're just looking at return to nitrogen, not to everything else. So if you're looking at your overall return across your field and your overall yield level, you've gotta realize that you're not gonna manage your way to get 300 bushel yield in all areas of the field if you've got some areas that just won't support that.
Daniel Kaiser:So really, all we're focused on is just making sure that the nitrogen you're applying with these, with the recommendations can be at least covered with the value of the crop where you're you're at least netting even or or coming out even with with the last rate applied.
Brad Carlson:Yeah. The point being that that when once you achieve that top spot on that, the yield plateau with the with the with the with rates is that there's some other factor than at that point that's controlling your top yield. You know, it's not nitrogen anymore. So adding more nitrogen is not going to affect that.
Jack Wilcox:Let's steer back a little bit toward water quality. What are some of the other ways that farmers in Southeast Minnesota can help improve water quality, understanding it's a long game? Kevin?
Kevin Kuehner:Yeah. I think, you know, when we look at all the tools that we have available in the Southeast, it's, it's somewhat limited, you know, in some ways because if you compare that to, like, let's say, our glacial till area to the West, we have a lot of edge of field project practices that you could do, like saturated buffers, bioreactors, you know, restored wetlands, things like that that can reduce nitrate. But in the Southeast, we don't have that ability. We have really good drainage, so we don't have that, sort of aspect. But I think the foundation is all what we've talked about, right, the the four r's.
Kevin Kuehner:But I think we recognize that even just with those tools, we're not gonna probably address some of our water quality goals with just those tools. We're gonna have to be thinking about other sort of aspects to this. And one area of interest, of course, is how do we keep our kind of third crops, small grains like oats and alfalfa acres and perennial crops, how do we keep that going in the Southeast? When we look at historically, you know, back in the sixties and seventies, you know, we had a lot more, continuous living covers out on the landscape. We've lost a lot of that over the last, you know, forty or so years.
Kevin Kuehner:So how do we keep keep what we have and also build more, right? And because we recognize to to get these reductions that we need, both for surface water and groundwater, we're gonna need roots that are growing all year round as much as we can, to get those reductions. We we know in our data, the data we collect, if we switch from corn and have alfalfa in rotation, we can see those nitrate reduct nitrates reduce by over 70%. If we have cover crops in the rotation and are able to use cover crops, like winter cereal rye or whatever, cover crop you're using, that all depends on the biomass. You know, how much biomass we're producing, but typically, kind of the the goal is to get at least about a thousand pounds of biomass before you terminate, and our the data would suggest that you would see about a 20 to maybe even 30% reduction in the nitrate by just using cover crops.
Kevin Kuehner:So if you can layer a lot of these practices together, it's not gonna be just one sort of, one approach. But if we can layer these together, we can maybe get closer to that 40% reduction that is currently, you know, right now the goal of the next twenty years for the statewide nutrient reduction strategy is to get a a 40% reduction by, you know, twenty twenty forty or so. So it's gonna take everything all hands on deck, you know, sort of thing to to get that goal. So
Jack Wilcox:What about, like, decision support tools, or is it were there lessons learned from the Root River Field to Stream Partnership, that kind of thing?
Kevin Kuehner:Yeah. So one thing, you mentioned the Root River Field to Stream Partnership. That was started about twenty years ago. It was a sort of an effort to get at these questions that we're calling asking today. Right?
Kevin Kuehner:Like, how much are we losing? When are we losing it? How effective are our new practices, existing practices, and what are those long term trends. One of the things we've been doing with China, with the data that we've been collecting is how do we make this more relevant to the farmers, and one question we get a lot of times from our farmers is if they're using cover crops for instance is, well, when should I terminate that cover crop? You know?
Kevin Kuehner:And we don't wanna terminate it too early. We also don't wanna terminate it too late. Right? Because we don't have it wanna have a negative impact on that next crop. So working with, a variety of researchers, including the University of Minnesota and Extension, we've we sampled a bunch of fields last year of cover crops, trying to create this relationship between the cover crop biomass and imagery taken with your phone.
Kevin Kuehner:And this is based off of research from other researchers that were done in Michigan and and kinda building off of that. But it's looking like that looks like a very possible thing that we can create. And so the idea is probably, hopefully, a year from now, we'll have a tool where you can basically, it's a website or an application on your phone where you can just take a picture of an area of your field that has a cover crop. It would then report back to you. You'd still have to measure the height of the cover crop with a ruler, but just that picture and that ruler measurement would tell you how much biomass is out there.
Kevin Kuehner:And and once you know the biomass, now you can start to estimate how much NPK uptake is taken by that cover crop. What's the percent nitrate reduction estimate, you know, from that cover crop? And also, we like to integrate a forecasting tool where based on the weather forecast, we could say, let's say, the next three to ten days, how much biomass would we would we would, have, over that time. So it could help the producer and the farmer decide, should I terminate it this week, or should I wait a week or two before I do that? So
Jack Wilcox:That sounds like a fabulous tool. We'll watch for that. Let's turn to Mary, who's been sitting patiently this entire time. Can you talk to us about grain gathering, and here in Olmsted County, what kind of financial help is available for people.
Mary Nesberg:Yeah, so here in Olmsted County, the Olmsted County SWCD has put together the Groundwater Protection Program, and that's their cost share program that helps farmers institute a number of practices that help establish that continuous living cover on the landscape. And what's nice about this program is that it's really adaptable, so farmers can choose if they wanna be planting cover crops, and they can get cost share payments of just like a base rate payment of $55 an acre, but it's also outcomes based. So they can add $20 onto that payment if they let the cover crop grow to 24 inches. Again, trying to achieve those larger biomass goals. If they're able to plant green, planting their cash crop into that living cover crop, they can add an additional $10, and so there's kind of these stacked payments that producers can start to earn.
Mary Nesberg:They also have a haying and grazing payment, and so if you're converting row crop acres into haying and grazing land, there's a payment for that. And then a popular program for them is growing alternative crops, and many of them, like Kevin mentioned, are growing oats, small grains. And so that one is a base payment of $75 an acre, and then if that's paired with legume cover crop, which they often are under seeding together, they get 25 more dollars an acre. Wow. And those legume cover crops that they're taking, and they're planting medium red clover along with the oats, A lot of them are taking a pretty big nitrogen credit for next year's corn, anywhere from 70 pounds to 100 pounds an acre.
Mary Nesberg:So that's what they're doing right now. I'd love to see more research in that area to kind of back up that big credit that they're taking, but it's what they're doing right now. So that program, like I said, the Groundwater Protection Program is expanded right now to neighboring counties with RCPP funding. So that was great to see the success of that amplified. Olmsted County is also helping to administer the TAP in program, which is the private well testing program.
Mary Nesberg:So anyone with a private well can sign up for a pre private well testing kit, and send in their well sample to get tested for five different contaminants, nitrates is one of them, and they'll get a free analysis, and then if their sample comes back high enough at that 10 parts per million or higher, they can qualify for a free reverse osmosis system. And to date, the program's a couple years old, maybe two or three years old, and they've installed two forty nine systems in our area, in the eight county area, so it's being utilized well. Both of these will be Both of those programs will be highlighted at my event, which is the Grain Gathering, on February 18 here in Rochester, and I'll be bringing people together to talk about oats. And so, we'll be talking about the soil health benefits of adding oats in between soybeans and corn. There'll be a farmer panel of some experienced producers who've been growing them for quite a few years in between that rotation, and then we'll also be talking about the agronomic recommendations and the economics of adding that third crop in, and how it's kind of like an opportunity crop and create some economic gains, and then some market opportunities as they exist, especially with the new mill, the oat mill being developed in Elberley.
Jack Wilcox:Excellent, fantastic. And we'll link to that conference or that event in the show notes here. Awesome. Is there, before we move on, is there a key website that someone can go to if they want to find out more about your financial incentives? Does your what would you recommend there?
Mary Nesberg:It's the Olmsted County's yeah, it's their website. It's SWCD's website.
Jack Wilcox:We'll find it, and we'll link it too, also. Excellent. Just to quickly open it up to the table, we're kinda running out of time. Is there anything else that we should be thinking about related to N BMPs and nitrate water quality issues in Southeast Minnesota?
Brad Carlson:Well, I just I just wanna point out that, you know, we had a fairly successful meeting as for Southeast the Southeast last year. That was kind of an outgrowth of Nitrogen Smart, the Nitrogen Smart program. We're going to plan on having a couple more of those this year, probably in late February, early March, something of that sort. At this point, we're we're don't have those nailed down to the exact date and location. We're thinking probably Zumbrota and maybe someplace else further to the south, But that's a chance for people locally to come and find out, you know, exactly what the situation is longer than a forty minute podcast, you know, most of the day.
Brad Carlson:And then in addition to that, our nitrogen smart curriculums are all available as online courses at our website, z.umn.edu/nitrogensmart.
Jeff Vetsch:Jack, I got a whole list of things I'd like to throw out there before we close. Great. The first one being, you know, incorporate a cover crop after early season or early harvested crops, things like sweet corn, peas. We got some edible beans in the area, silage corn, a lot of that. Try to incorporate a cover crop after those crops in the fall, and that'll help minimize the nitrate potential loss from those areas.
Jeff Vetsch:Similarly, if you are applying manure in the fall and you have to apply in early October or late September, incorporate a cover crop with that can be very helpful. If not, try to delay those manure applications later in the year. Follow setbacks near streams and sinkholes with either nitrogen fertilizer applications or manure. Inject or incorporate nitrogen fertilizer wherever possible. And finally, think about source.
Jeff Vetsch:You know, there may be some of these fields that have a higher end loss potential, maybe anhydrous ammonia would be a better targeted source in the spring on those fields compared to like UAN or urea.
Mary Nesberg:The other really well put together report that came out over the summer was with the nitrate, the Southeast Minnesota Nitrate Working Group, which was a group of, I think, 18 stakeholders that came together to make a pretty comprehensive list of recommendations for the area of how to address nitrates. And a lot of those are best management practices or ideas for what could happen with education, outreach, research. And so that report has a lot of awesome nuggets, many of which we've talked about today for people who are interested in, like, what that the big overarching goal could be and how they all relate to each other.
Jack Wilcox:Fantastic. I think that about wraps it up for today. Thank you everybody for being here. Mary Nesberg, Dan Kaiser, Brad Carlson, Kevin Kuehner, and Jeff Vetsch.
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:We'd like to thank the Agricultural Fertilizer Research and Education Council, or AFREC, for supporting the podcast.
