Nitrogen fertilizer management & surface water: Context, successes and challenges
Hello. You're listening to Advancing Nitrogen Smart, the podcast series from University of Minnesota Extension. Here we unpack and examine the latest data driven research based information all about nitrogen so that you can make the best decisions for your operation.
Jack Wilcox:I'm Jack Wilcox at the communications desk here with Extension. Sitting here with me are Daniel Kaiser, nutrient management specialist with Extension, and Brad Carlson, Extension educator and water quality specialist.
Jack Wilcox:In our last podcast, we focused on the relationship between nitrogen management and groundwater and drinking water. Today, we're gonna switch gears and talk about nitrogen management and surface water.
Brad Carlson:Well, Jack, the surface water issues really kinda start with the federal Clean Water Act in the early 1970s. Now, if you went back to that time, there was a lot of what we call point source issues. There was direct discharge from factories, wastewater treatment plants, and other places where clearly there was some pretty significant contamination issues going on. You think about some of the historic things that happened in this country, things like Love Canal or the Cuyahoga River and Cleveland catching on fire and some of that kind of stuff. And there really was a clear public appetite to try and get a handle on those issues and deal with them.
Brad Carlson:And a lot of those issues were identified, cleaned up, and dealt with through the nineteen eighties, I mean, through the nineteen seventies. And so by the nineteen eighties, the the federal government, kinda reopened the the Clean Water Act and then expanded it to nonpoint source pollution. That's just the small little bits of, contamination coming in from all over the landscape. And so while it's easy to deal with a factory or and its owner as far as what they're putting into the water and how they're gonna clean it up, When we start talking nonpoint source pollution, we're talking tens of millions of acres. We're talking about, you know, hundreds of thousands of landowners, you know, and varied all the way across the country.
Brad Carlson:It's not so simple as to just put a regulation in place to deal with this many acres and this many people. And so while the Clean Water Act does include nonpoint source pollution, there's not a lot of teeth in it. It's really calling for education and voluntary action. And and so the the one thing that the the other thing I should say that that happened as a result of the Clean Water Act is it delegated the authority to deal with a lot of the enforcement for the Clean Water Act to the states. You know, it's kind of the federal model as far as dealing with a lot of this because a lot of these issues, do happen, you know, locally, and and it's a whole lot more efficient for the states to deal with it than, than for the federal government to try and do it.
Brad Carlson:So in Minnesota, if you went back to the early nineteen seventies, at that time, our Department of Natural Resources was primarily focused on walleyes and white tailed deer, and so there really wasn't the feeling that they were the best agency to be dealing with this. And so in Minnesota, we actually created the Minnesota Pollution Control Agency to enforce some of these federal pollution, laws, the, the Clean Water Act, Clean Air Act, and some of that kind of stuff. And I know a lot of people question sometimes, you know, how did we end up with all these extra agencies in Minnesota? It's really kinda historic. Again, if you went back at that time, you know, the agencies we had were doing other things than this, and so it was kinda felt that that there should be an, some entity to deal with these federal mandates that were kinda more specific to what was, being being, talked about at the time.
Brad Carlson:Bringing this all forward, you know, and and a lot of that happened in the eighties, and there wasn't really a ton of direction at the time. In Minnesota, I guess what's interesting is is we've got a a clean water rule that that passed through the legislature, chapter seventy, eighty, and it defines different contaminants in water. And so you can look up many individual contaminant, and you can see what's considered to be the the level at which it becomes in violation, and something needs to be done about it. You know, one of the intriguing things about that is if you look at that whole list, nitrate isn't even on there. And so, you know, that that kinda calls the question, like, well, what's going on here?
Brad Carlson:You know, we're spending all this time. It seems like we almost only focus on nitrates and water these days, and it's not even in the, the clean water standards. Well, if you went back to that era, I think one of the the key things is, our primary contaminant for surface water in Minnesota has been and probably continues to be phosphorus. It's the limiting nutrient in our our surface water as far as growing plants or algae, and so there's already enough nitrate or nitrogen in the water. If you add more, it doesn't do much.
Brad Carlson:But for every bit of phosphorus you add to the water, it grows more algae, it grows more weeds, and creates more water quality problems. And so really a lot of the focus historically in Minnesota, on our surface waters was phosphorus related. Well, flash forward to the nineteen nineties, and suddenly this issue of hypoxia in the Gulf Of Mexico ended up kinda rearing its head. And and so what I'll explain what hypoxia is. It's it's a natural phenomenon.
Brad Carlson:It's probably been going on forever, and it happens where every major river in the world discharges into the ocean. And and so if you think about it, the fresh water in a river is is much more conducive to life than the saltwater is in the ocean. And also, the those these freshwater systems are picking up nutrients and and so forth that they're fostering a lot of life. And so wherever they dump into the ocean, it creates this mixing zone where there's an abundance of life compared to the ocean in general. And if you also could imagine, it's pretty clear, most people will realize that rivers flow high in the spring and they flow low at late summer.
Brad Carlson:That that's kind of how our precipitation patterns are. So there's a large amount of fresh water and nutrients going into the ocean in the springtime, and then that kind of tapers off in the fall. So these areas where we see this large discharge foster a big growth of life, algae, zooplankton, and whatever else comes in with it in the spring, and it can't sustain itself because the fall goes down towards the end of summer. And so when when the flow starts to taper off, a lot of these things die. And then when they decompose, they end up robbing the water of oxygen.
Brad Carlson:And so that is what is considered or called hypoxic, having no oxygen, and then stuff starts to die. So as I said, that's a natural phenomenon, been going on forever, goes on all over the world. So what's the big deal? Well, a lot of major fish kills and problems in the Gulf Of Mexico in the nineteen nineties were kind of examined, it was decided that the hypoxic zone that's coming out of the Mississippi River was significantly larger than it historically had been, and it was adversely impacting a lot of major industries, particularly the shrimping industry, and there was a lot of pressure put on the EPA to deal with this problem. So they convened a committee of scientists to examine it.
Brad Carlson:You know, my understanding is that they simply couldn't reach a complete consensus. There was a lot of disagreement related to many aspects of this, but the prevailing opinion was that the hypoxic zone in the Gulf Of Mexico needed to be reduced by about or needed to have a reduction in the amount of nitrate coming into the ocean by about 50%, you know, 45%, I should say. It turns out that while phosphorus is our limiting nutrient in freshwater, there's plenty of phosphorus associated with the salts in the ocean, and really the major limiting nutrient there is nitrogen. And so it is nitrate that's causing a lot of this problem, and not phosphorus. I mean, there certainly are phosphorus elements to it also, but specifically the Gulf Hypoxia Action Plan, which was finally adopted in 02/2008, calls for a 45% reduction in the amount of nitrogen running down the Mississippi River in order to try and shrink the hypoxic zone to what's considered normal.
Brad Carlson:Important to remember, I'll hear some people talk about, well, our goal is to eliminate the hypoxic zone. We can't get rid of it. It's a freshwater river discharging into the ocean. It's always going to be there. The issue is more of how big is it supposed to be and what are we supposed to do, you know, in order to kinda get it under control.
Brad Carlson:So the way the EPA decided to address this was to delegate to the states. Now remember when we talked about the Clean Water Act, we said that nonpoint source issues were voluntary and addressed through awareness and education. And so the EPA really didn't have any mechanism to try and and and force action on dealing with hypoxia. So what they did is they delegated each of the states in the Mississippi watershed to develop what they call a nutrient reduction strategy. So the idea being that if each of these states reduce their total contribution by 45%, the end result would be a 45% reduction in what was going down the Mississippi River.
Brad Carlson:And so every one of the states, I think the, Missouri River was exempted, but take Minnesota, Iowa, Wisconsin, Illinois, Indiana, Ohio. We all have a nutrient reduction strategy, and each of them is trying to set a blueprint or a plan in place to reduce the contributions of nitrogen into the Mississippi River by 45%. In Minnesota, we chose to have a benchmark system. And so the initial target that was put in place was to have a 20% reduction by 2025, which I think everybody recognizes is this year. And then at that point, there would be a reevaluation of the status and and a kind of a a update of the plan moving forward.
Brad Carlson:And so that's kinda where we're at today is is the evaluation has happened, and now we're in the process of of rewriting our plan kinda moving into the future. If you look at the state overall as far as where the nitrogen is coming from, you know, in general, the the biggest concentrations or or the biggest loads are kind of across the southern one third of the state that really shouldn't come as any surprise as we've referenced in the past. You know, it's kind of an artifact of our annual cropping systems that, you know, particularly we've found and and, again, that's a topic we've covered in other podcasts, so we're not gonna go into great detail here. But when we're properly managing nitrogen fertilizer, as much as two thirds of the nitrogen that are is coming through our drainage systems and ending up in the river is probably attributable to natural sources in the soil, and in a lot of cases, is accumulating post growing season. And so it's really not surprising then that a lot of the nitrogen flux is kind of in the same parts of the state where we see the, most of our row crop agriculture.
Dan Kaiser:You know, the general fact that it's all water based, and that's, I think, one of the challenges, as we see increases in annual precipitation in some of these areas is trying to meet some of these because we could still have a minimal amount of nitrate coming through in terms of concentration, what's in the water coming out the tile line. But in effect, when we start talking about load, load is more of if you start looking at the basis of load, it's on the total precipitation. So I think that's gonna be one of the challenges. You know, as Brad mentioned, phosphorus is also in some of this nutrient reduction strategy. And we we start looking at phosphorus, you know, reducing phosphorus from overland flow with things like buffer strips in places where we can capture it, I think it'd be a little bit easier to deal with phosphorus than it is with nitrate that is soluble and can move down through the the soil itself.
Dan Kaiser:So that's gonna be the I mean, the challenge, I think, moving forward with some of this, particularly when it comes to nutrient reduction is, you know, how do we manage this particularly when you can't control the weather? And I know that's one of the topics of, some of our advanced Nitrogen Smart, looking at, and so I'll just kinda put a plug in for that, looking at, what options we have to try to reduce some of the nitrate that's coming out of the tile lines. But that's really, I think the challenge moving forward is is the fact dealing with the load as a whole is, you know, we might be able to deal with the concentration as much as possible, but it's challenged, especially get to that 45%, if we're getting more rainfall.
Brad Carlson:In Minnesota, what we've done is is as the federal government has delegated the states to produce a nutrient reduction strategy for the entire state, we have developed watershed plans in Minnesota that go even down further to a local level. And so, we have these on what we call HUC eight watersheds. HUC stands for hydrologic unit code, and the eight means an eight digit number. That's not important really to anybody. Although some people ask, well, what does that mean, or where did that come from?
Brad Carlson:It has to do with the size of river or the size of watershed. And so a Huck 8 watershed is, roughly speaking, is about the same size as a county. There's there's, I think there's 80 about 80 of these in Minnesota, and we got 87 counties. And so they're roughly about that size. And each of these watersheds has developed its own plan, which is is led locally in most cases by either a watershed district or a soil and water conservation district.
Brad Carlson:In some cases, they were kind of headed up by the the county water planners. A lot of the how environmental things are handled at the county have been evolving. And so a lot of those positions have been kind of absorbed or rolled into some other, roles too from various individuals. But regardless, these plans are kind of on a ten year revolving basis. They they, you know, the state is because we couldn't really deal with, the whole state at once, kinda went through a phased process, where different watersheds were developing their plans.
Brad Carlson:They were reviewed. They were approved and so forth. And and so these these watershed plans have action strategies. It's important to know that the watershed plans also include other things in them. So if we go back to the Federal Clean Water Act, there's there's issues with other things like sediment in the water.
Brad Carlson:There could even be issues with water temperature, and so forth. And and so all that gets rolled into the plans. The the process through which that a lot of that is dealt with is the acronym or the abbreviation is TMDL, which stands for total maximum daily load. A lot of people say, you know, how do you come up with that? There's really no daily load from agriculture.
Brad Carlson:Like, for instance, today, there's, if the ground's frozen, there's nothing going into the water. That that terminology actually originates with the beginning of the Clean Water Act. If you look at, for instance, a wastewater treatment plant is going to discharge into the water. You can't just simply hold all of our waste up on the landscape forever. We'd have giant reservoirs of sewage, and we certainly don't want that.
Brad Carlson:The issue becomes how much do you have to treat that before it can be discharged into the water. And so the terminology is total maximum daily load. How far does it have to go before it can be released in the water? And so that's that's kinda where that terminology comes from. From an agriculture standpoint, as I said, we don't have a daily load, but regardless, the the terminology TMDL coming from the Federal Clean Water Act is kinda stuck.
Brad Carlson:And so the the watershed plans incorporate all these different TMDLs for various contaminants into them in the in the area. I mean, overall, Minnesota's got well over 15,000 lakes and how how many thousands of miles of streams and so forth. You couldn't write an individual TMDL plan for each one of these water bodies and and, you know, not only not write them, but after that, you probably wouldn't have enough staff to go back and do anything about them. And so by having a finite number of these watershed level plans, we can actually spend more time focusing on them and working on them. The important thing I think about these plans, and we've mentioned already the effect that we've had in Minnesota of our clean water heritage funds, is that we've delegated or designated, I should say, a a fairly significant amount of money to work on conservation projects in these watersheds.
Brad Carlson:You know, historically, a lot of our our water conservation stuff, soil conservation stuff was handled through the federal farm bill. But I think a lot of people recognize that there's been some issues with that. You know, in the past, they've had some caveats relative to multiple concerns or priority practices or, you know and, you know, in some cases, you've got individuals who don't participate in the farm program and so forth. And so, they have not been, far reaching. Our Minnesota money that's delegated to do conservation in our watersheds has very few, of those caveats put on them.
Brad Carlson:And so we're able to focus that money on dealing with a lot of the, water quality issues that are present locally. And so, you know, for the last decade or so that we've been doing these, we've really taken care of a large backlog of of, projects that have been kind of sitting out there not able to get funded. I think what's encouraging or interesting is is as we move forward, because a lot of that backlog has been cleared up now, is we look forward to being able to start targeting some of that money into specific areas and practices that we hope will is gonna have a lot more, impact on reducing nitrate loads in our water.
Dan Kaiser:That's one of the things too. It's kinda nice when you start looking at some of these things being targeted on a local or, you know, smaller levels, the fact that you get a little bit of, I wouldn't say policing, but a little bit of pressure from growers within the same area to, you know, kinda come together and come up with things that work for those areas. And then, you know, ultimately, hopefully, put some pressure on if there is, you know, people out there that are doing things that, you know, they shouldn't be doing that, you know, maybe you can kinda come together with your neighbors and figure out, things that are are best for you. Because that's one of the things I think that's that's challenging with state of Minnesota being as diverse as some of our soils and some of the issues we have across the state is that there isn't a one size fits all strategy across the state. And that's really why, you know, we look at our best management practices being keyed towards specific areas to try to address some of that variation because, you know, it's one of the things, I guess, is in my end, if you have any regulation does come down, I mean, it's it's really one of the things that, you know, we try to push for on the research side is the fact that, you know, not all strategies will work in all areas and that things need to be more local when it comes to management.
Dan Kaiser:So I think there's some positives there, particularly on some of these plan implementations being on a smaller level because I think it allows for some of that, variability be brought into some of what what's being recommended in some of these areas.
Brad Carlson:Yeah. I think that and probably the last thing I'll say about the watershed plans is because they're local. You know, if you're interested in in doing some kind of conservation project or if you wanna be involved in in writing these or determining what's in them or how it's addressed, talk to your county SWCD, and they'll they'll kinda clue you in on what the process is and what the opportunities are to get involved. And because, again, it's it's it's being directed locally. You know, kind of the last, there's, I guess, two two more, points, I guess, we wanna make in the podcast, and I've already alluded to this already, and that is that the nutrient reduction strategy is being rewritten this year.
Brad Carlson:And we've already kind of done the the pre evaluation of where have we gone. We had a target of trying to get a 20% reduction by this year. Did we reach it? No. We didn't. Unfortunately, if you look at the data, what we'll you'll discover is is there does appear to have been some significant improvement made on loss of nitrate. However, the increase in rainfall over the last decade is kind of, you know, pun intended, has kinda washed it away. So the total load is a calculation between the concentration and the amount of water running through the system. So even though our concentrations have gone down because there's so much more water going through the system, we're actually seeing still quite a significant load going down the river. And so, you know, that that's also an issue we're going to have to look at addressing.
Brad Carlson:You know, if if, it could possibly be that we may need to look at storing some water on the landscape and just simply keeping it out of our our the river or out of our systems, and and cutting off some of that load. You know, that's part of what's being addressed. There's parts of the states where that'll work, and there's places where it won't. But, that's going to be some of the what that, nutrient reduction strategy looks like when it gets rewritten and released. And people can look for public comment on that starting in in probably mid to late twenty twenty five.
Brad Carlson:That'll be out there in draft form for people to take a look at. There's one last issue, I guess, I wanna talk about here, and that's nitrate concentration in surface water. This has not been a really big issue, but it's something, I guess, to be aware of. And we talked a lot on the last podcast about nitrate concentration in drinking water and groundwater. You know, there's all these questions frequently about, well, doesn't that cause a problem in surface water too?
Brad Carlson:Well, that's really been kind of a I don't wanna say a black box, but it's really not been clear or cut and dried what impact, high levels of nitrates have in surface water. Probably the one area that has been identified by the pollution control agency is cold water streams that that there is some impact on on, particularly invertebrates and then, therefore, trout populations in cold water streams. So the state has identified what they consider to be cold water streams, and then they've looked at nitrate concentrations. And there are 27 streams currently listed as impaired for nitrates. And those, of course, have a, an action plan on how they intend to deal with them.
Brad Carlson:So, you know, as we've said throughout a lot of this conversation, as we mentioned in our last podcast, when it comes to, dealing with these issues, whether we're talking groundwater, whether we're talking surface water, or we're talking about surface water concentration, really, all the practices that we recommend and and the potential mitigation strategies are all kind of the same. There's there's not separate practices for groundwater or surface water. It's all kind of the same stuff. And so from that standpoint, from our standpoint, we tend to lump all this together because in the end, the action plan is gonna look the same regardless of what the local issues that we're dealing with.
Dan Kaiser:And that's one of the things too, I think, kinda to close with, you know, on my end is, you know, we when we start talking about a lot of this stuff that, you know, nitrogen management is the foundation, you know, of a lot of when we start talking about reductions, whether it's surface water or reductions in nitrate to groundwater. That's one of the challenges because with nitrogen, since it is a leaky system, particularly nitrate is, you know, once it's out there on the landscape, there really isn't a whole lot we can do to try to prevent loss other than having a crop that is out there that can take it up. So, yeah, it's one of the things why we stress a lot of the best management practices when it comes to nitrogen management is that, we wanna make sure that at least when we're making these decisions and putting the nitrogen out there that, you know, we're protecting it as as best as possible. Because, you know, again, you know, unless there's a crop out there, we know there's times of the year when there isn't a whole lot of water usage by plants in the landscape that that nitrate can be lost.
Dan Kaiser:So that's why the focus really is on the best management practices at least to try to give us a good starting point for management to give us an idea in what should hopefully reduce the risk for loss as much as possible.
Brad Carlson:Yeah. I I attended a lecture a few years ago, and the speaker was an ag economist, I think, from Purdue, and he described nitrates in water as a wicked issue. Wicked not meaning evil, but wicked meaning just so very difficult to produce results, positive results. And and, you know, that that's kinda what we're faced with. This this isn't this just isn't a simple thing that we can, you know, do this and the problem's taken care of, know, particularly when we've talked in the past about, you know, maybe as much as two thirds of the nitrogen and nitrate in our water is coming from natural sources, meaning whatever we do for fertilizer management isn't going to meet the nutrient reduction standard of 45%.
Brad Carlson:You know? And so you know? But that being said, the management of nitrogen the proper management of nitrogen fertilizer is the cheapest and easiest thing we can do. So we have to do that because the rest of that stuff is gonna end up costing us some money. So, you know, I I guess that's kind of the the final party message for farmers is, I think it's important to realize what these issues are, why they're out there, you know, why you're being asked to do some different things.
Brad Carlson:You know? And and this is going to continue to evolve. We haven't really talked a lot about what's been going on in the last year in Southeastern Minnesota, and that's going to continue to evolve also and, might be a subject for a different podcast.
Jack Wilcox:Brad Carlson, Extension educator and water quality expert, and Dan Kaiser, Extension nutrient management specialist. Thanks very much.
Dan Kaiser:Thank you.
Jack Wilcox:Do you have a question about something on your farm? Just send us an email here at nutmgmt@umn.edu. Thanks a lot for listening and we look forward to seeing you next time.
Jack Wilcox:Advancing Nitrogen Smart is proud to be supported by the farm families of Minnesota and their corn checkoff investment through Minnesota Corn.
