In this episode, Dan Andersen discusses manure spills, including common causes of spills, how spills are contained, and use of technology to help prevent equipment failure. Dan also looks at the causes and timing of fish kills in Iowa, as well as the downward trend of livestock and manure-related fish kills. Find show materials here.
Dan Andersen 00:06
Hello, and welcome to our second edition of talking crap, a podcast by Iowa State Extension and Outreach, where we discuss insights into the science, technology and best practices surrounding manure management. Our objectives are to build awareness about the challenges farmers and the broader agricultural industry face around manure, and demonstrate solutions in areas of innovation. I'm Dan Andersen, associate professor and extension specialist at Iowa State University in the Ag and Biosystems Engineering department, where I get to focus on manure. So yes, that means I get to think about crap a lot. If you want to talk more about any of the ideas presented in today's episode, feel free to reach out via phone or email, or you can send me a note on Twitter, or whatever calling Twitter these days, to @drmanure. In today's episode, we will be talking about manure spills and fish kills and other minerals. How often do they happen, why did they cause fish kills, and what people and companies are trying to do to make that situation better. So buckle up, check out the handout for this week's episode, and let's have a discussion about benign manure spills.
Dan Andersen 01:11
Before we get started, let's start with a manure fact. Manure is complete fertilizer and that it contains all the goodies, nitrogen, phosphorus, potassium, sulfur, and many more micronutrients that the crop needs. But it isn't always a balanced fertilizer that matches all the nutrients to crop demand. Historically, manures tended to have too much phosphorus relative to nitrogen, and in some cases, it still does.
Dan Andersen 01:35
However, different feeding strategies can limit phosphorus levels of manure, which along with practices like rotating which fields receive manure, or implementing solid separation and phosphorus separation methods can help balance the manure to the crop nutrient needs. I think this is something we've seen a fair amount of especially in the swine industry, where we see relatively high levels of DDGs, in many rations these days. That's increased nitrogen content in the manure. Given how we've changed feeding and fosters availability of DDGs, it's tended to bring down phosphorus in the feces at least to some level. And along with high levels of phytase, we might see a manure there that is much more balanced. Unfortunately, we haven't been able to replicate that success on some of our other manure species. But I do think new approaches are helping to get that closer to reality in many more situations. If you're interested in learning more about phosphorus circularity and some of the practices that help support phosphorus along with manure and water quality, stay tuned for a future episode, where we'll dive into phosphorus management with manures.
Dan Andersen 02:48
However, today's topic is going to be about fish kills and manure spills. I saw a recent article and had a chance to answer some questions since they sent me a 'What do you know about this and what can you tell us [about this]?' as an interviewer about manure related fish kills in Iowa. And since when you give an interview like that, I wrote up like a four page answer to the questionnaires and they use one or two snippets of what I said, I thought it'd be a great chance for me to take some of that and provide a larger perspective on my thoughts so that you don't see that itty bitty little one side note of this is what Dan Andersen from Iowa State had to say.
Dan Andersen 03:30
Just like last time, there's a graphic with some of the information available from the Iowa DNR spills and fish kills database to help provide some perspective on the conversation and give you a visual in case you're a visual person who wants to see what I'm talking about. One of the pieces I have of information I have available on that graphic is all fish kill events that have been reported by year from 1981 through 2022. This is by no means perfect, right. It is the reported fish kills that were tracked by the DNR. So if there was a fish kill that wasn't tracked, wasn't reported, it won't show up. But it is the best data that we have. And I think it should be treated like that a piece of data, an indicator of what is happening rather than a perfect number. As I look at that information, a few things stand out to me. There's a fair amount of variability year to year, not surprising the weather plays a role for both fish kills and fish kills related to livestock. And more importantly, both fish kills in general and fish kills related to that livestock industry are down significantly since around 2012 I have a couple other graphics to help understand fish kills and I wanted to point them out now.
Dan Andersen 04:45
About half of the fish kill events reported in that timeframe. So the last 40ish years were anthropogenic, meaning they were caused by people or something that we're doing. About a quarter of them were deemed natural fish kill events, that be low oxygen sags that we think would naturally occur. And then about another quarter of them were caused by an unknown reason, or reason that couldn't be tracked or found. So one of the things that really stands out then when you see that is, when you look at the actual number of fish kills that occurred, the number one cause of fish kills in the state of Iowa, at least according that database and reporting is manure. So let's start with how does manure in a stream kill fish. When manure enters a water body, it starts to undergo decomposition by the bacteria. During this process, organic matter in the manure consumes dissolved oxygen in the water. And that's that's really what the fish are breathing, right. So just like us, if you can't get air, you can't breathe, you suffocate, and die. Fish are having the same levels or same issue, right. So if the oxygen level in the water drops, the fish and other aquatic organisms first become stressed, and then if it's low enough, they suffocate suffocate from the oxygen depletion.
Dan Andersen 06:00
In addition to just that organic matter in the manure, there's other things like ammonia. Elevated ammonia levels can stress fish and other aquatic organisms, making them more susceptible to the negative effects of low oxygen levels. Specific impacts of manure spill on fish and aquatic life depend on various factors, the volume and concentration of the manure that was spilled, the characteristics of the water body, how much water is flowing, and the response timing containing and addressing the spill. Those are all definitely complicating factors, things that are really important, and things that are hard to talk about in much detail. As manure contains higher levels of organic matter and ammonia spills where manure enters a water body have a more rapid impact on aquatic life than spilling many other things. These fish kills often occur rapidly, making it easier to trace and assign the cause of the fish kill to a specific event like that manure spill events that cause a rapid fish killer just easier to trace down the evidence is still fresh, we can see signs of what happened and assign a cause, then events that are more slow acting or driven by maybe rainfall, where it's nonpoint, source pollution or the weather in general.
Dan Andersen 07:12
Another graphic that I wanted to share was the timing of fish kills. fish kills, at least according to the Iowa data are much more common in July, August and September. Clearly those months are riskier, but why? Some people, and this occurred when I was a kid, used to say dilution is the solution to pollution. It isn't, right. If it's flowing down the river, it's still there, right? The same amount went down the river, but concentration levels are what kills, concentration kills, right. So dilution can help reduce some of that concentration. And maybe we don't get that local or immediate impact. But we still see some of the signs that pollution did occur. So more dilution water can reduce the negative impacts, lessening the opportunity for a fish kill. This doesn't mean that the pollution level is reduced, though only one particular negative aspect that we are measuring, seeing and counting with the fish kill indicators. In general, drier summers make streams more vulnerable to fish kills, as there's just less dilution water from a stream, it isn't flowing as fast, there's just less water. Just as importantly, warming warmer water holds less dissolved oxygen. This means that spills where oxygen can consuming material is spilled, makes oxygen levels dangerously low more quickly, especially since microbial reaction rates tend to speed up with increased temperature, meaning they'll break down that organic matter faster, and that it is a more rapid decline in oxygen levels giving less chance for oxygen to diffuse back into that water. Most livestock manures in Iowa are land applied to fields in the fall. Iowa has around 14 to 16 billion gallons of liquid manure from livestock facilities that must be applied annually as a crop fertilizer. Due to logistical constraints, much of our manure is fall applied. We have shorter weather or shorter time periods in the spring before we need to get planting once the soil thaws. Often times soils are wetter and more prone to compaction, so fall tends to be a period where maybe we have more opportunity or more days to get that work done. This also means that we're trying to get that manure out there in a time period when streams are more vulnerable. We all have already seen that those warmer weather conditions can increase microbial activity naturally cause lower oxygen levels and make any spill that enters their breakdown more quickly and drop that oxygen level more rapidly. If we compare that to maybe something like synthetic fertilizers, where some is applied in the fall, but more is applied in the spring generally than what we see with manure in the spring flow rates are higher maybe it's an indication that there's less risk and less opportunity for a fish kill to occur.
Dan Andersen 09:55
In addition to that, the forms and physical properties of synthetic and mined mineral fertilizers are drastically different from that of manure. Farmers use many fertilizer sources. For example, solid fertilizers might include MAP, DAP, urea, or gases, fertilizer, like anhydrous, ammonia, and less, they're spilled directly into a stream of weather event, rainfall, right has to take them from where they were put to the stream. This isn't true for liquid manures, or for liquid fertilizers for that matter. They are already in a liquid form, and they can move independently should a spill occur, right once it's out on the soil surface, it will move always downhill, but it will move. The other thing I wanted to comment on it was while we try and put on the same amount of fertilizer in terms of pounds of nitrogen, or pounds of phosphorus, the actual volumetric application rate to get there is drastically different. Manures tend to be much more dilute. And at first glance, this may make them seem not as risky, right, it takes a much smaller amount of fertilizer entering a stream to add the same amount of nitrogen or phosphorus as it would take from manure. But it also means that we put less volume on per acre. And as a result, there's a smaller chance for that fertilizer to move, unless there is that rainfall or weather event. Because the small amount won't flow over the ground as easily towards the stream, it has a much better opportunity to soak in before it gets there than maybe we'd have with a high volume of liquid manure. It also just means that when we're using those commercial fertilizers, we could handle less volume, right smaller tanks, smaller trucks, smaller everything moving it around. Or, just as importantly, fewer trips right to handle that same amount of fertilizer equivalent. So even if a break does occur, or a leak occurs, there's just not as much material that ends up moving or it has that chance to soak in. And that also means that if the spill does occur, we get to build a smaller berm or we don't have to worry about stopping as much stuff and that just makes our response a little bit easier.
Dan Andersen 12:06
I did want to switch topics away from that immediate spill for just a moment and talk about nutrient movement from fields. Nutrient movement, by which I mean mostly nitrogen and phosphorus from both manure and synthetic fertilizers is important. Excessive nutrients from manure, including nitrogen, or fertilizers like nitrogen from anhydrous ammonia, can both fuel algae growth, which can further contribute to oxygen depletion during their lifecycle right. Eutrophication occurs when nutrient levels mostly that nitrogen or phosphorus become high in water body. These nutrients provide food for the algae to grow, as well as other aquatic plants. As a result, algae blooms can form, cover the water surface blocking out sunlight from reaching submerged plants and organisms, and as they do that some things will die. Eventually that algae bloom will also die and decompose. Bacteria and other micro organisms consume the decaying matter and with it consume oxygen from the water to help break down that material. The decomposition of the algae depletes the available oxygen in the water, which can lead to a condition known as apoxia or low oxygen levels. Fish and other aquatic organisms rely on that oxygen to survive. So if we have areas where that oxygen isn't present, it can be a dead zone. And when we talk about the Gulf of Mexico and its dead zone, that's generally what we're referring to. However, this style of event is slower to occur, and that isn't it isn't within hours or even days of a specific event, like fertilizer application, it's often driven by the weather. And it tends to be more systematic, right? It results from our cropping system and land use and weather rather than yes, no with an event. Because of that it is much harder to trace that condition back to something when you're reporting, right. So in the Iowa DNR spill database, this might get classified as a more natural event. They mentioned for instance, dissolved oxygen sags as a an event or an environmental event, as it is difficult to tie back to a specific person, farm or management strategy practice. Because while the fish kill happen, and it can be seen, there just wasn't one triggering event, it was it was more general than that. These are indirect events is what I'd say and the word for that we often use is nonpoint source pollution and just in general nonpoint source pollution is much harder to trace than something that we think of as a point source, which is that immediate spill or a spill of liquid manure that makes it directly to a stream.
Dan Andersen 14:40
Okay, with that I think that's enough on fish kills, at least for now. And I want to take a step back and focus on manure spills. Again, I have a graphic tracking that reported spills as a function of time and we see a similar trend. There's a steep decline in reported manure spills starting around 2012 and then another significant drop maybe around 2017. Manure spills can occur at several points in a manure management system. There are five components in any manure system, manure collection, transport to the storage, transport for land application, land application, and then that storage itself. If you tuned in for the previous episode, you've probably heard about that in our systems sort of thinking and how do we put these systems together? I think overall, most manure spills are related to the transport to the land application area and the land application itself. Farmers do a good job maybe not a perfect job but a good job of managing manure storage levels. And in Iowa, many storages are under roof in a barn making them less prone to overflow with different weather conditions. Moreover, in a year, like '23, where much of the state has been really dry, we just don't have as much risk of a storage overflow occurring. In other years where we get above average rainfall or significantly above average rainfall in short periods of time, especially if the storage was already near full, these overflow events can occur. While manure systems are designed to accommodate some rainfall in them, the weather doesn't always live by the design standards we set. So there is an operator sort of managing how do I prepare for those events occurring that has to go on, and certainly that sort of preparation is different in a state like Iowa, as compared to maybe a state like North Carolina where you might have to prepare for hurricane in the chance of those larger precipitation events occurring factor into how much storage we design, as well as what do we have to do to be ready to prepare should that event occur? For the most part, we use two different systems to move manure from the storage to the land application area. One is what I'm going to call a truck sort of tanker system, where individual loads of manure are driven from the farm or manure storage to the land application field. The other is an umbilical or host system where there's a pump at a farm, maybe some booster pumps along the way, and we move liquid manure through essentially a hose from that manure storage all the way to the application field. And I'm going to talk about these two, a little separately because I think they have an impact on what we think might happen or what might cause a spill.
Dan Andersen 17:19
So a truck tank system has, I think two primary causes of spills. One is equipment failure, a seal on the tank doesn't work or get stuck in an open or slightly open position and manure spills out. The second is a traffic accident involving the manure transport vehicle. Maybe it's hit by another vehicle or the operator loses control of the vehicle. For instance, if they get on the shoulder of the road, and the road is soft, the shoulder soft and they get pulled into the ditch and the heavy tank makes it impossible to correct that before they're in the ditch. Regular inspection and maintenances are performed on manure application equipment to try and prevent or minimize bad seals and keep everything working properly. However, manure is difficult to work with because it is filled with solids. We have challenging weather conditions in the fall. Oftentimes, since we want to get manure on when soils are generally 50 and cooling, we're working around some freezing conditions, manure sticks to everything we get ice build up that might plug, sometimes we're working around mud and that mud can make some of these things stick in that work as well, and it also leads to parts breaking. From my perspective, equipment is continuing to improve. And just as importantly, our ability to understand manage, and know those potential points of failure has improved, so we're doing a better job of changing them out. And that has helped some of those manure spill levels. Unfortunately, spills do happen. And the other comments I really wanted to make here is most of these spills have limited size, right? We know how big the tank is. So if we end up with the tank in the ditch, we know how much manure we spilled it's gives us a nice chance to know what we're dealing with what we're working with as we formulate how we're going to respond. With the umbilical system we use hoses hooked together with couplers to move that manure from storage to field. The infrastructure is generally temporary is that helps reduce cost and it makes it much more flexible to go from field to field or to different fields that we might not land apply to every year. So we unroll the hose at the start of the job and then roll it back up to the end. Just like with a garden hose being coiled and uncoiled and then moved across the ground to water your garden, it adds wear to the hose. If too much wear occurs, eventually the hose will get a hole in it. They do sell menders for the style of hose so if you can get if you get a hole you can patch that back together, but there's a life right so eventually those hoses were out.
Dan Andersen 19:52
Manure applicators try and grade their hose and try to use new pieces at the most critical locations. So for going near a stream that's probably a great place for a hose that is new or well-repaired hose, but occasionally hose breaks still do occur. When it does, the applicator shuts down, repairs the leaks, and then starts reapplying manure. Again, this is a place where I think technology has been a blessing. Many systems today have a flow meter at the lead pump, or that first pump near the livestock farm, and oftentimes another near the tractor. If those numbers don't match, we have control systems that can help with shutdown, right, so if the number of reading is different by more than a set amount, we get automatic shutdown. In every system, we aren't using that, but almost all systems today have at least one flow meter and then some pressure sensors along the way, especially at booster pumps. The pressure sensor can tell if there's a leak, by effectively looking for a sudden loss in pressure, or a large enough change in pressure that it would be unexpected based on how we're operating. So you get a sign of that something is wrong right there in the cab of your tractor and you can get the spill stopped very quickly. Most of the booster pumps have valves to close and shut down to active stops to keep all the manure from that's in the hose from leaking out and limit it to just wherever the line is that that actually has the leak. And I think this is extremely important. As I look at the evolution of these umbilical systems. In the 2000s, when these systems were really first gaining popularity, oftentimes there was one crew member placed on a four wheeler and his job was just to drive back and forth and inspect the line looking for a leak. And then to radio in, hey, we need to shut down right we have a leak happening. The newer systems, the response time is much more quickly that when you were a little bit reliant on the person being in the right place at the right time. And just some of these newer monitoring systems make that much more rapid of a detection. And we need that right. The newer technology with auto shut fff in real time is being sent to the tractor caught have monitoring is more responsive. And if you think back to those early 2000s systems, we might have been flowing somewhere in the neighborhood of 500 to 2000 gallons a minute. systems today are probably in that 1000 to 5000 gallons of minute sort of flow rate. So a spill today, a lot more manure could come out more quickly. So getting that response time down was extremely important, maybe not too limiting spills, but to limiting the impact that those spills have, and especially on them causing fish kills.
Dan Andersen 22:29
So again, I think this is a great sign our equipment manufacturers are understanding some of the challenges building that into their systems to have fail safes to help make management a little bit easier and a little bit more manageable. And then a third part of the spill process that I wanted to talk about was reporting spills. I will requirements are that any release be reported as soon as possible, but no later than six hours after the onset or discovery of that release. And again, I have a graphic to help understand failure to reports. Overall, the number of failures to report has tended down with time. Great, thank you for all of you doing a good job. The manure failure to report has always been quite low, and I think that's really important for us to keep doing. Spills do happen. Failure to report is a personal responsibility, right? That is something that you got to make a decision about. Sometimes spills will happen. There's not much we can do about that, but reporting is all on us. I'd say reporting any spill is important. I'd encourage everyone to over report, including if I had a spill in the field and we're pretty confident it won't impact water quality. Report it to the in our tell them what happens. If it doesn't impact water quality, the DNR might not include it in the spill database, it might not be a spill that was something that they would consider reportable. But knowing what is going on is important for helping us all, the whole manure industry, do better. And then just one last comment before we wrap up for today. Manure is an important part of fertilizing crops in Iowa and making livestock systems more sustainable. There certainly is still work to do. But I think it is important to recognize that improvements have occurred. There are fewer manure spills each year, farms are treating manure like a resource and want to use it appropriately, but moving high volumes of materials sometimes results in accidents. The number of fish kills from manure spills has also seen a decrease. We are innovating. I think there's a lot of new technology that has helped make manure equipment safer and especially safer from a water quality perspective. Things like auto shutoff getting better tanks, better trucks, things with better monitoring on them to know what's happening go a long way, but we all need to keep innovating. There are opportunities here to keep improving. And I think the last 10 years have shown us that we were making strides. Hopefully we can continue to make those strides as we move forward.
Dan Andersen 25:04
With that, I want to thank you all for joining us for the latest episode of Talkin' Crap. Take a look at the show notes on our websites for links and materials mentioned in this episode. For more information or to get in touch, go to our website, Iowa Manure Management Action Group, which you can find at www.extension.iastate.edu/IMMAG/. If you found what you heard useful today, or it made you think, we hope you'll consider subscribing to our show on the podcast app of your choice. And that's it for today. So, signing off from a job that sometimes smells, but never stinks, keep talking crap.