Foaming at the Pit: Causes, Consequences, and What We've Learned

Manure foam – what is it, why does it happen, and why should you care? In this episode, Dan Andersen breaks down the bubbling mystery of manure foam, the science, the risks, and the research. He also explores best practices to stay safe and informed based on years of research and forming instances across the Midwest, explores what is happening under your slotted floor, and what you can do about it.   

Show Notes

Transcript

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Hello and welcome to Talkin' Crap, a podcast by Iowa State University Extension and Outreach. This institution is an equal opportunity provider for the full non-discrimination statement or accommodation inquiries, go to www.extension.iastate.edu/legal. In this podcast, 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 to demonstrate solutions and areas of in the ag and biosystems engineering department at Iowa innovation. State University, and today we're talking about manure foam, something that's caused barns in the Midwest to explode. Researchers like me to do a fair amount of investigation or a deep dig into what's happening, and also just provide safety and environmental concerns for pigs and people. So what I really want to talk about today is, what is foam? What do we know about why it's happening? What we think we've learned where we're going and what you should do about it when you see it? A few things to remember, foam appears to show up seemingly randomly, but there is some structure about why it's happening. It's a major safety hazard. So we have had barns explode or fires occur when that especially when that foam is disturbed, when then there is some sort of spark or a treating event to let it on fire. Even then we don't have that explosion or a spark occur, it's still a safety concern because there is a lot of gas trapped in those bubbles. And should we do something to break a bunch of those bubbles rapidly? We get quick gas release, and that's mostly methane and hydrogen sulfide. And while I focus mostly on that explosion risk, with the hydrogen sulfide in there, there's some air quality risks for pigs and people, and then it's just a management hassle, right? If the third or half of your pit is taken up by foam, rather than space that we can use to store manure, there's more pressure on when we need to apply having to get that barn out of the pit. What am I going to do to make it to my next application window real quick? What we're going to try and talk about today is just the science behind foam, the risks and management options you can take. If you do have any questions, I encourage you to either hit me on Twitter, send an email to dsa@iastate.edu, or just reach out and talk to me about the foaming concern. A little bit of background. What is manure foam? Well, starting back in somewhere around 2010, 2012 we started to see this gelatinous goop on top of some manure storages. This goop would catch bubbles of gas, and we called it foam. And I think we called it foam because, well, foam is bubbly. And in some ways it's, it looks like that, right? It's a bubbly, gelatinous mess, and I've seen it anywhere from big bubbles that might be more of a froth like you get when you blow bubbles in milk, to something that looks more like the consistency of Cool Whip, only a dark brown and smells like manure. So there is some variation in that, and we'll talk a little bit about why and what it means and how to think about it. But we started to see it roughly in that time period, and people started asking questions about, why is it on my barn and not on your barn? Or, I've never had foam before. What did we change to make this happen? Or, man, I have a whole barn and that half is foaming and this half isn't. Come on. It's all the same. Why is it so different between the two? And what can you scientists tell me about it, or what should I be doing about it? So we got funded from Iowa Pork Producers. They funded both Iowa State University, the University of Minnesota and the University of Illinois, to start doing some work on what are the causes behind foam, and hopefully, eventually, what are some things we can do to mitigate some of the challenges that come along with foam. And like anyone would do, the first thing we did is we said we're going to sample this problem away. And what I mean by that is we got something like 100 barns. We went to them on a monthly basis, and we got a whole bunch of manure samples, essentially enough manure samples to the point where, when I'd get back to Ames and look at my cooler, I'd make a joke about, well, there won't be any foam in that barn. We've moved it all into the cooler here so that we could study it. And certainly that's not true, but there were quite a few samples. Every time we went to a farm, we try and get anywhere from two to four samples between how deep that manure is to really understand is there a spatial difference with depth? Sometimes trying to sample two barns at a site, especially if we had one barn that was foaming and one barn that wasn't. But really trying to get a good assortment of both foaming and non-foaming barns at any month. So we did that for about a year. Got a lot of data, and one of the things that was really helpful for me is just observing those barn surfaces throughout that year on how they change from not foaming to foaming, or they'd get a crust. And I know we all can look at our manure, but I don't know that we all do look at it every month and really pay details to what's that surface is looking like. And that was one of the things we recorded every time we were there, depth of manure, depth of foam, thickness of crust. And just looking at them, you'd sort of get this trend, because we paid attention to the same barn every month coming back, opening the same pump out, looking at it was what was happening. And one of the things that we saw would often happen is right before it foamed, it would get a crust. But underneath that crust, if you broke through it to get your manure sample, there'd be this light, small, foamed bubble material. And that was really an indicator that the barn was probably going to be foaming in a month or two when you came back, if there wasn't an intervention made. So it sounds simple, it sounds dumb, but it was actually relatively interesting to me, and it made us start asking questions like, Well, is it getting a little crust on it because that's acting like a cork on a champagne bottle, holding some of the bubbles in and then it's just interacting with stuff at the surface to make this foam, or is the crust necessary? And it's not always necessary. We saw barns that never crossed foam, but it did often have a trend where we'd go through this almost foaming, this soft, moist, sort of bouncy crust, and then we'd get to foam. Now some barns would get that crust, and next time, when you come back, it'd be a little harder and a little thicker, and when you broke it, there wouldn't be any sign of that gelatinous group goop right below the crust, and those didn't turn into foam. So what's the difference? Why was some happening and some not? And we'll try and talk a little bit more about that. Alright, I wanted to start out by saying a couple things here, but we're going to talk about manure foam, and I really want to talk about different types of foam. First I wanted to talk about trying to blow bubbles in water, milk, whipped cream, and then what meringue is, and trying to talk through a little bit about what those differences are. So when you take water, and I have a four year old daughter just learning how to swim, and one of the things they were teaching her was blow bubbles in the water, right? It's a training exercise to get used to putting your face in in the water. And kids find it fun, right? Bubbles are glorious and fun to play with, so she took to it and puts her face in the water and blows some bubbles. And when you watch it, it forms bubbles, and you can see them momentarily, but they break really quickly, right? And that's sort of the no fun of blowing bubbles in water and and it happens because the surface tension of water is relatively high, right? So there's essentially, it's so high that it puts enough pressure back on the air in there that it pops the bubble, and there's no structure to help hold the bubbles together, and you get basically an instantaneous collapse of the bubble. So you can blow them, but they don't stick around. So water's like a party that ends before it starts or ran out of your favorite beverage of choice way too quickly. And there's a few things we can take away from that. The first to me is surface tension is really important, and the other is that no stabilizers, no foam, so it takes a few things to make foaming happen. Another thing that we might think about is milk. And as a child, I loved blowing bubbles in milk. It was a fun pastime, and one of the first things I noticed is while I could never get enough bubbles in water to make it overflow the glass, if you're playing around with your milk, you certainly can, and you better not do that, because your mom will tell you all about it. So what makes milk foam when water wasn't well, there's a few things in it. There's proteins, and they might provide some state, like stabilization to the foam. But there's also at least a little fat and milk, and that fat is a surfactant. So that surfactant stuff essentially helps lower the surface tension. So if you think about surface tension, it's like stretching a rubber band. The further I stretch it, the more it's going to pull back. But if I add surfactant in there, the rubber band doesn't pull as hard, and that helps bubbles stick around a little bit longer. Now that foam isn't really stable either, you might enjoy some froth on your coffee, and that's probably what we should call it, as froth instead of foam. It you can make the bubbles. They're there. They hang around a little bit, but if I come back tomorrow, they're all going to be gone. And that probably isn't what I'd call a good stable foam, but more of a froth that's there for a little while. The third one I wanted to talk about is Cool Whip. And Cool Whip is sort of an engineered foam, right? It's, some people would say perfect, because we cheated and engineered it. But essentially, we're adding emulsifiers and gums. You whip some air into a fat and water base and throw a little sugar in there to make it taste good, and it will hold its form, maybe not indefinitely, but for quite a while. And especially if you buy the store bought Cool Whip, it's a long, long time. And if you make it from whipping your cream yourself, maybe not quite as while, and you can sort of see the difference between that is, what emulsifiers were we adding, right? So the store bought whipped cream has these gums, these real product emulsifiers in them to help them hold that consistency, whereas, if you whip it yourself, you're getting air entrained in it, but it still doesn't have that stability and eventually will more it pops right. Essentially, the break down. And then there's everyone's favorite version of a foam, maybe not everyone's, but it's a pretty tasty one meringue on your lemon meringue pie. And that's the one that, to me, at least from the science and chemistry that we sort of uncovered in manure foam is where we get to. So generally, there's a lot of water in manure. So you might say, Well, I think pig manure should be like water. It makes bubbles and they break instantly and oftentimes. That's true, but there's other stuff in manure, right? There's fats, oils, some proteins, maybe a few carbohydrates, or at least a fair amount of fibers, and as soon as we have those fats and oils in it, we've maybe moved more towards that milk regime, those bubbles happen because we've lowered the surface tension from the foam or from from the having the fats and oils in it. Now, in no case are we probably like Cool Whip because we haven't added emulsifiers and things like that to make the foam work. We need something that's more natural, and that's why I tend to think a little bit more of that meringue. But when you think about what more stable as a fluffy substance that's on top of that delicious lemon. The other thing that we do is we add sugar, and that increases viscosity and helps stabilize it further. So when you think about, let's say, in this case, rather pressure inside is big enough that the rubber couldn't hold itself. And in some ways, that's what's happening naturally. There's this structure probably filled with proteins, maybe some fats and oils around this bubble, and if we get too thin, so either the bubble gets too big, or water, in this case, drains away from that material, the bubble wall will get thinner and thinner and thinner, and eventually it goes pop right and opens up and lets material out. So if you can do things to make it drain more slowly, those bubbles will be more stable and stick along around longer. So in meringue, we're adding sugar to that egg protein mixture, and that causes a couple things to happen. It causes more water to stay in the bubble structure longer, because we've increased the viscosity, we've made it thicker so it drains more slowly. So that's sort of a food chemistry of what's happening and how you can make different types of foams and why they behave differently. And I wanted to do that because I think they give us a conceptual framework to how to think about manure foam. So when you're making that source. We need some tension, surface tension reduction, have a conceptual framework, but we said, well, these are the three things that foam really needs. How can we think about it in terms of the science of foams that we know. In this case, manure ended up, foaming manures end up having basically the same three elements, right? So gas supply, in this case, it's generally methane from microbial fermentation. They need some surface tension reduction. And it turns out there are oils in manure, right? So while pigs or people, or all animals do a relatively good job of consuming oil. Some oil is passed through and ends up into the pit, and microbes will break down those things into sort of short, medium and long chain fatty acids. Those fatty works tasty muscle. But it's in this case, though, there's the protein rich particle that interacts with some microbial produced poly-liposaccharide, and it makes these small, really viscous particles, or, as I like to call it, the goo, that surrounds the foam holds it together, and really provides a lot of that stability. So just like a meringue, microbes in manure produce goo that trap the bubbles, hold the bubbles together, except instead of making a delicious dessert, it's setting the stage for danger. All right, so we did a fair amount of work on foam, and I'd like to tell you it was all really well thought out, intelligent work. And some of it, at least was, but some of it was, at times, throwing spaghetti at a wall and seeing what would stick. So the first thing we did, we said, we're gonna go get all these manure samples, and, well, we have to measure them for something. And what should we measure them for? And we said, well, maybe knowing something about the types and number of microbes in the manure would be useful. And then we said, well, we know surface tension, viscosity all play a role, so we should measure those things too. And then we said, well, we know stuff about manure. We'll just measure standard manure chemical properties and see what those can tell us. And finally I said, Well, I'd like to measure how quick is it making methane? Are we sure that these pits just aren't making more bubbles? And that's why they have foam, because as a kid, if I wanted more bubbles in my chocolate milk, I just blew a little harder and and all of a sudden they appear, right? So, we got all these manure samples, we'd bring them back to the lab, we'd set them on a lab bench and incubate them at room temperature for about three days measure how much methane they made. And one thing that jumped out at me after one month of doing this and then two months of doing this, is manures that had foam making methane significantly faster than manures that don't have foam. You might say, Well, that was intuitive. Anyone could have known that. Maybe, maybe you could have guessed that. Maybe we should have guessed that, but it was nice to have data behind it, and what we found is, on average, foaming manures were making methane three times faster than those that weren't foaming. Now, every barn that made methane more quickly didn't meringue, we need egg whites or the protein, we need a sugar, necessarily have foam, but it was a pretty good indicator of which ones were foaming or which one weren't. And at first we said, All right, that tells us something, really, it's making me this methane more quickly, and that's part of the equation, right? But more than that, I came up with this idea. Well, maybe it's drying stuff to the surface. In the wastewater treatment world, there's this process called dissolved air flotation. Essentially, it's just like recovering stuff from a shipwreck, right? You take your raft out there, deflate it, lower it down, and then we put all these, essentially balloons into whatever sunk below into the ocean. We blow them up with some sort of gas that's lighter than water. And next thing you know, we've got enough buoyancy to float. In dissolved air flotation, you're doing essentially the same thing. You're putting air into this liquid material, trying to get it to stick to whatever you want, to remove, oftentimes, small solid particles, and it causes those particles to float to the surface. So what I'm trying to say is, yes, higher methane production rates lead to more bubbles because, well, there's just more gas. But the second thing they're doing is sort of acting like that dissolved air flotation system, in this case, a dissolved methane flotation system. And those methane bubbles are sticking to small particles in there, acting like flotation devices and dragging those particles to the surface. And that was sort of a new and interesting finding. And what that implied to me is, well, there's two reasons that methane is important. It's not just that it's high. It's that it has to separate this goo that would generally break down into the manure, up and onto the surface. And when you looked at the types of things that were going on, and a great chemist, Steve Trabue, who works at ARS here in Ames, started doing some chemical analysis of that goo, right? We tried to do it for both non-foaming manure, foaming manure, and then the foam itself. And essentially, what he found is that this poly-liposaccharide wasn't really present anywhere except in the foam. And there's two reasons that could happen. One is, well, there's some micro about the surface just making this special goo that really matters to us. And while that might sound like a great theory, and it could be true, we didn't really find any data that supports that. Instead, it probably is something that's made in the manure, gets broken down by some other microbial system relatively quickly and eaten up and consumed unless it makes it to the surface where there isn't as many microbes to be working on it, and it gets to stick around and starts to accumulate. And it's that stuff, that goo, as it gets to the surface, that's really trapping the gasses and starting to concentrate them at at dangerous levels. Okay, so a couple other things. I promised a little discussion on on surface tension, because we said that's important. And if you've ever tried to blow bubbles with your kid and make homemade bubble solution, you've probably taken water add a little bit of essentially, detergent or dish soap, right, to lower that surface tension down, and all of a sudden you went from not making bubbles because the surface of tension was too high to making bubbles. But the truth of that matter is you can keep adding surfactants and lower the surface tension a little further and a little further and a little further. And if you do that, you sort of turn that rubber band or that elastic into something with no elasticity left, sort of your worn out pair of underwear, right. They just don't come back to their original form. And what we actually see in manure systems is that foaming manure tends to have a higher surface tension than non-foaming manure. And at first, I was like, that doesn't work with the theory of what we thought at all. We thought we needed to lower the surface tension. But what we really, I think, in the end, decided, is that the surface tension is generally low enough in manure that if bubbles form, they pop relatively quickly because there's no elasticity left to hold that bubble together. And what we saw is that the surface tension in that manure was just really proportional to how many volatile fatty acids were still left in that manure. So short chain volatile fatty acids are something that microbes eat, generally, relatively quickly and turn into methane. So in that foaming manure, one of the things we see is it's making methane more quickly, and it is keeping the volatile fatty acid concentration lower. So there's not as many of them, the surface tension comes up, and all of a sudden we're in that ideal bubble forming range, rather than too easy to break bubbles. So it wasn't what we expected, it wasn't what we were looking for when we just started measuring surface tension, but it was a useful thing to measure, because it helped us understand where we were in relation to forming bubbles in the system. Now I don't want to talk about that one too long, because I don't think it's one of the two main things that were changing, I think that gas production, or the gas source, was really important, and then the other one that's really key is that still foam stabilization method, mechanism. And here we got a little lucky. We were starting to get a little frustrated not understanding what was happening, but we invented this thing called the foam stability test. And by invented, I mean we ripped it off from sort of the beer industry, where you pour a beer a certain way and see how much head it makes and how long that head lasts. And here we said we could do that with manure. We'll just blow some air through it, and then start measuring how much foam it made and how long that foam lasts, and try and relate it to things. And we did that, and we saw that foaming manures were vastly different than non foaming manures. And agreed. We knew that was going to be the case, or at least had strong feelings that that should be the case. But one of the things that let us do was say, All right, we're just going to throw some stuff in there and hope for the best. One of those eight things that I throw in probably will make foam not happen, and then we'll be in great shape. And I think our lucky breakthrough actually went the opposite way. We showed up and we got these materials, and we had a had one called tannins, right? So if you're a woodworker and think about oak, that's a wood with high tannin, and that's sort of where tannin comes from. It's used to tan hides, but tannins naturally are in a bunch of different things. So we had this tannin, and people had shown that by adding tannins to manure, you can lower the rate that the microbes are making methane, mostly because they don't like tannins. And we said, All right, we're going to do that. We're going to throw it in this manure sample, and then we'll blow some air through it, and we'll let this other one that we had tannin through sit two weeks, and then blow some air through it, we'll measure how much methane it made in between, and start saying, like, if we reduce the methane, does that help it not foam later? Well, we threw the tannins in, and we go to do this foam test, and I had a manure that was foaming and a manure that wasn't foaming, and we did the manure that was foaming and yep, it's still foamed. And I was like, okay, that shouldn't have done anything at time zero anyway. And we did it again with the manure that wouldn't foam after we threw the tannins in. And we're like, what the heck it made this foam that it didn't before, and that foam was really stable, really stable in that it would have a half life of about three days. So it took three days after we made it for half that foam to break down. I was like, What the heck is going on here? I ran down a floor to talk to Steve, and we started talking it through, and we're all like, this is really strange. This is really weird. What happened? And then Steve said, well, tannins are known to interact with proteins, so maybe it's just those proteins that are binding with it to make the foam stable. And we're like, All right, yeah. And then we started to do some reading, and it said that oftentimes protein foams look great. And I was like, yes, foam and barns look great, but it doesn't quite answer the question, right? What is binding these proteins in manure in reality, to make them stick together? And do all manures have these proteins? So Steve did some great work on the the proteins in the foam, and unfortunately, found their kind of corn protein. And that's pretty much ubiquitous, right? We're always going to have corn protein. We feed a fair amount of corn, and we're like, Well, that one's tougher to get rid of, but that's where he really started looking for that poly-liposaccharide. And I'd like to say he was looking specifically for it, but we were looking for what the goo might be, and just trying to get a chemical breakdown of it. But what he found was that this poly-liposaccharide probably is interacting with the proteins a lot like what we get from meringue, to make that matrix and form some stability. And that all started because we got a little lucky, right? We were just throwing stuff in, and happened to see a positive result. So I think that tells us a lot of where the the material was. The other thing I will mention is one thing that I think we got a little lucky on too, was I decided to measure particle size of foaming manure, non foaming manure in the foam. And one thing that was weird was that foam was filled with 2 to 25 micron sized particles, which is essentially a silt sized particle or a fine silt, so really small particles, and you could sort of look on the foam and know that it was filled with that style size of particles. It's super solids rich. So that made sense to us. But one thing that we kind of got a little lucky on was we saw that the non foaming manure had more particles in that 2 to 25 micron range than the foaming manure did, and that's really where we came up with that dissolved air flotation system, where it was attaching to fine particles and bringing that microbial goo to the surface. So all that to say, I think we got a pretty good understanding of the mechanism of why are we getting foam? What's happening? Well, it's more methane. It floats this microbial goo to the surface. It interacts with the churn and makes this protein. And next thing you know, you have sort of a meringue, a bubble filled meringue on the surface of your manure pit. Now there's additional questions that aren't answered from that right, like, why does this pit foam? And that one doesn't when it's the same pig, same management, same feed system. So the last sort of leg on that was we did some feeding trials, and we measured microbial community on lots of manure. When we did feeding trials, we could tell a few things. One in our individual feeding trials, when we started with a clean manure tank, we never got foam, but we did see that some diets, especially higher fiber diets, tended to have more methane production potential than their non-foaming counterparts. Now, in our studies, when we started with clean manure tanks, we never turn that methane potential into actual methane production. It would make some methane, but they really didn't develop the microbial community to be vastly different, but it still was sort of like starting a campfire. The wood's there, we've added kindling. All we need now is the match. So that was one of the things that I think was key from the feeding trials, just understanding sort of, how do different diets influence that carbon potential. But we also saw that different feed ingredients were capable of changing the microbial community. Unfortunately, we only saw that half of the microbial community was influenced by the feed ingredients that we're using in any given study, and the other half was, who knows what, all the other stuff that we didn't have control over, maybe how much water an individual pig was drinking, the temperature the manure was at, maybe just what was ever in the microbe of the pig's gut before we started. And then you can only modify it so much, but there was still a lot of variability. And I think that sort of answers the question of why one barn might foam and one doesn't because it is microbial community related. And from all our microbial sampling, we got distinct differences in the microbial community of foaming manures compared to non-foaming manures. So we can say we're different, and you could say, Well, you got a super bug in that foaming manure. No our data didn't really indicate that. The types of bacteria were present in both manures, foaming and non-foaming, but the percentages of different types changed greatly, right? So the community structure was different. So good news, no superbug. Bad news, it's different for some reason. And well, it's probably partially related to feed, but it's partially related to all those other things. And one of the things we saw it was partially related to is what type of microbial community you already had. So if you had something that was well established, it tended to be harder to change it to a new type of microbial community. So if you have a non-foaming manure, there's probably some resistance to staying a non-foaming manure. Your manure, microbial community, doesn't want to change unless we do something to really cause change. And what I mean by that is, when you cause a disturbance, like agitating your manure, pumping it out, maybe there's a chance to recultivate that manure, but it might settle back to where it was, right? It has a tendency to settle back towards where it was, unless there's a management change. Same with foaming foaming manures, right? If it was a foaming manure, it probably wants to stay a foaming manure, unless something happens to change that community structure. And from a treatment standpoint, that's both good and bad, right? If you have a non foaming manure, you're like, all right, I'm living the good life, I'll probably stay non foaming, but there might be time periods where I should worry a little more. Essentially, right after pump out. If I'm a foaming manure, it says, well, it might be hard to change it, because my community structure is already there. The community is working relatively well together, so unless there's some event to really knock them off course, it might be hard to change, which is one of the reasons why we say, if you have a foaming manure and have had a foaming manure before, that's probably a good time to consider treating your pit right after you pump it out, because it's most prone to being changeable at that point. There was a couple other questions, like, why us? Why now? when we started seeing these problems in the Midwest, and there's a couple things. One, we probably started feeding more high fiber diets. Essentially, DDGs got popular. They got cheap, and that meant more micro food. Another thing that we tended to see at that time is that embedded fats in the manure are less well digested than fats are added back. So those DDGs had some oils embedded in them, and while pigs do a pretty good job of breaking up that oil and digesting it, more of it was passed through because it was embedded. These days, we tend to see people doing a better job of separating oils and then where appropriate, adding them back to the diet, and that improves digestibility. The other thing that was happening at that time, especially in the Midwest, was we were really improving water conservation in barns. So we saw a lot of people switching to wet dry feeders, less manure per pig, same amount of manure excreted per pig in terms of solids, just less water ending up in the pit. And there's sort of this ideal range for making methane from manure. It's probably somewhere between like 6 and 10, 12% total solids content. And by getting those water conservation measures in place, we started to thicken our manure, and we were thin, and we're starting to move higher and higher on that ideal, closer to ideal methane range, right? So we started to get to the bottom side of that. And then I think with time, we've gotten maybe a little bit thicker, a little bit more nutrient rich, and we've started to get hung out on the other side of that, where now we're a little too high in some of those things to be ideal for methane production, and that's probably reduced our propensity for foam, in many cases, not that we can't foam. The microbes are very adaptable, so even around that higher side, there's still some opportunities for foam. But I think that was one of the reasons at that time we saw it more prevalently in the Midwest, and maybe we saw sort of that amount of foaming come down for a little while. It has a lot to do with sort of being in that ideal range and cultivating that microbial activity. I know I've started to see and get a few more phone calls from foam, maybe further away from Iowa. So I'd like to think we're a leader in the industry, and we were a leader in pursuing that, and maybe some of the areas are starting to catch up on some of their water conservation methods, and starting to see some of that manure get more carbon rich and start to get to maybe that area where it has more chance for foam. And that's both good and bad, right? It's bad that it has a chance to foam, but generally, when we think about manure management and using our manure, that more nutrient rich manure tends to be easier to apply, lower rate, more economical, and competes better with the fertilizer. So it makes a lot of sense that people would move that direction. Okay, I wanted to talk a little bit about why foam is dangerous. So foam contains about 70% methane. That's 700,000 ppms of methane. Methane is explosive, or within its explosive range, between 5 and 15% so the foam itself is way above that range. But when you break those bubbles, start diluting that methane in the air in the barn, all of a sudden you are in that that explosive range. So things that cause sudden collapse of the foam release a lot of methane at once. Agitation, maybe washing your barn, because the water falling through breaks those bubbles. That's when we really get to those dangerous gas release and have potential for explosion. So anytime you're doing that, really take attention to ignition sources, heaters, static electricity, electrical arcs, welding, smoking, things of that nature, right? Anything that gets into that foam will start to break the bubble. It'll start to burn them. If we've released a lot of that gas all at once, that's when we get the explosion. I know a few people have told me I've dropped welding slag in the pit. A be really careful about that. If you have foam, be extremely, extremely careful. Even if you don't have foam, you can sort of get a fire down there at the pit, and they'll say, Well, I saw it burn across the barn. And I always think it when I hear these stories. I'm glad I wasn't there. I would have panicked. But that foam itself, when you started on the fire in the pit, it does tend to be too high to get an explosion. It sort of burns across that foam. And it does get hot, it does get worrisome or dangerous, but since the bubbles are contained, it sort of breaks them in a controlled pattern as it moves across. And I think that has helped, in some cases, avoid that big bang or big explosion, if we've done something like started to pre-soak our barn, to wash it while we had foam, and then we get that same spark, oftentimes from a pilot light, that's when we've tended to see more of those, those types of explosions. So there are a couple things you can do. One, try and avoid those risky activities, right? If we are breaking foam, make sure we've done what we can to minimize a spark occurring. If you do need to weld in your barn, put down a slag mat to catch the slag. Don't let it fall in the pit. If you have foam and it's a problem and you're going to do something to sort of break it, we definitely need to be ventilating. If all the pigs are out of the barn, we still need to be running minimum ventilation. I know, especially in the winter, we want to keep the barn warm. It's tempting to really turn those fans down when we don't have pigs in the barn. We do tend to see foam for more often and and you could say, Well, is it a change? Because we suddenly stopped feeding the pit new manure, and maybe, but it's probably just that we no longer have manure, feces in urine falling through, breaking some of those bubbles, so the foam builds up faster than it was being broken by stuff falling through. And then if we do get something happening, like a spark, well, there's been more methane that's there to in the foam and in the barn to get us to some of those explosive levels. So what are some things we can do? What should we be thinking about in terms of foam mitigation? Well, there are some prevention strategies, and I know one that we don't have necessarily a lot of control over, it's often dictated to us, either from the integrator or from prices of feed ingredients, is thinking about that feed combination, how you're feeding your pigs. We know that feeding higher fiber ingredients, things that are less digestible to pig, puts more fuel into the pit. It puts more carbon into the pit. So you can think about, is there a way I can formulate rations to sort of adjust that to reduce my risk, and the answer might be yes or no, right? It might be one that you could do something. It might be something where it doesn't feel like it's achievable in what you have control over. And I certainly understand that. The other thing to think about is solids management. Microbes, especially anaerobic microbes are really slow growing only about five to 15% of the energy they eat actually gets turned into microbial biomass. The rest is turned into carbon. And what that means is, if I get rid of them all, it takes a long, long time for them to grow back. And oftentimes these guys are hanging out where the carbon is. So if you have a sludgy layer in the bottom of your pit, well there's more microbes in that layer generally, right? So if those solids are like sludge lagoon, where all the volatile solids have been eaten, I wouldn't say that's true, but when we think about a deep pit situation where we do a decent job of getting it worked up every year, and those styles say somewhat fresh, that probably is true. And that means one of the things that you can do, even if it won't solve the problem it has the potential to help, is trying to make sure we do agitate thoroughly, get as many of those solids, especially those settled materials, out of the pit every time we're agitating, because it gets rid of the inherent microbial community that was there, and it causes an opportunity for change. It also gets rid of carbon that was their food source, right? So if I take away all your food, you're not going to stay happy. You're probably going to try and move along. And while these microbes can't get out of the pit, they won't be as happy. And and some other microbes that are more adapted to survival and thriving at low, lower carbon contents of the manure probably will take over instead of the ones that we tend to see when we get to those higher ones. So I can't tell you that getting rid of those solids will solve all your problem, but it is certainly a way to help. It's something that we see in anaerobic digestion right there. We're often trying to hold on to solids or recycle solids to keep the microbes in the digester so that we can increase methane. And here we're really trying to do the opposite. effective. people try using some water have an There are some other approaches to treatment, and rather than being maybe more system approaches, they're more tailored to specific treatments. So there are things that we can add. We talked a little bit about surface tension and said, well, surface tension of foaming manure is higher than non-foaming manure, so if we can lower the surface tension a little bit more, will not formthose bubbles will break more quickly, and oil lowers the surface tension. I won't have that foaming capacity, the foam stability I had before bubbles pop really quickly. So that sounds good, but if you wait two weeks, three weeks, four weeks, that crop oil starts to get broken down by those microbes. And one of the things that we said earlier is that as we break down oils, especially, we think we're making this poly-liposaccharide, and that all of a sudden makes the foaming situation worse, that's really high in ammonia and hydroxide, and it sort of has this soapy, rubbery feel, and it's a surfactant. It helps Another one, and the one that's probably become most popular is thinking about ionophores. So ionophores are targeted to reduce, essentially, methane production in animal guts, and the way they work is essentially trying to make it so that you don't make acetic acid, you hold it into some slightly bigger chains of carbon that can be absorbed through the intestine more effectively, and really stopping that last step of turning into methane. And we think about that in animal body, well, there's somewhere else for that carbon to go. Right? The carbon chain gets absorbed into the intestine. The animal uses that material to form new cells or whatnot. In a manure pit, it doesn't work quite the same way. We might be able to throw that ionophore into the manure stop that methane process, or at least reduce the rate of that methane process for a while, but the carbon still there. It doesn't disappear. So it can be lower that surface tension again, and it can be effective, effective for a while at keeping the methane production rate down, but it probably more so in the long run is more effective because it changed the microbial community. Some other microbes who wouldn't have naturally been there and been part of that degradation pathway, get to be more dominant in that pathway. They would have been in the manure to start with. But rather than being 3 to 5% of the population, all of a sudden they're the dominant 20, 30% of the population. That's really doing that step. So we're just changing the type of microbes barn, maybe that's an option. If you're looking for that can do that. And I know some that people have used are narasin, which is Skycis, that's a pig additive. Some people have used romance and all of them you're trying to put in at roughly five pounds per 100,000 gallons of active ingredient. I think if you've had a foaming history in the past, doing that right after agitation or pump out makes a lot of sense, because you're trying to change the microbial community. If you find yourself in a situation where there's a fair amount of foam in your barn, I like to think of that as six to eight inches. It's a good time to treat if you have that foam, you need to make sure that you're getting the product down into the manure to be effective. It's a powder, so if you just throw it in and it gets hung up on the foam on top, it's not going to help us out. So if you take that mix, it into a bucket of water, spread it out through the pump outs, we've tended to have more luck in terms of treatment. And then the final thing that I have seen people consider or try is really treating that protein. And I know I said it's a corn protein. It's ubiquitous. There's plenty of it in manure, but there are things that attack proteins. So proteases are an enzyme that do it. You could buy protease enzymes add them to the manure that's perfectly acceptable. Some people have tried to use probably help break down some of those proteins, depending on how many proteins are in your manure, right? So you can sort of look at what does the manure sample look like in terms of total I did want to just mention that ventilation, especially anytime you're doing a treatment that breaks foam quickly is extremely important. So if you are going to throw in a surfactant, or if you're going to try and water in that ionophores by running sprinklers because you're between turns, or if you're going to agitate a barn, ventilate, ventilate, ventilate. The other thing I wanted to just say is there's no single fix to the foaming situation. There are different approaches that you can try. I think they they have various successes. And the truth is, we don't know long term, how well some of these are going to work. So if I add ionophores to the manure, I've had great luck with it. But is there a point where we've changed the microbial community enough that even when we're adding the ionophore that it will still make methane, still float some of this goo to the surface? And the answer is, we don't know. All right, so I wanted to sum up a little bit and tell you where we're at. So why does foam appear in some barns and not others? Well, we can relate it to at least a few things. The microbial community that is formed in that manure is extremely important. We know that the diet we're feeding the animal, the animal itself, is important in influencing that, but it only explains something like 50% of the microbial but really, those methods are about lowering surface tension, community that develops. The rest is things that we don't nitrogen and organic nitrogen, and say, you know, is it really know yet. And that means that even when I have two pits right achievable to try and push more of that organic nitrogen into next to each other, same barn, same feed, same pig genetics, trying to break the bubbles. they might not same form the same microbial community in the the ammonium form? It may or may not be effective. manure. And I wish that's a question I could give you a more satisfying answer to, but that's where the science is. There's a lot of things that we don't understand about the microbes in manure. I think that's an area that's that's right for more science, and we'll continue to probably get better at as microbial methods have improved. But when we think about why it is, we can sort of say, well, they're the same. They're managed the same and and maybe that's increased their risk relative to barns that aren't feeding as much fiber, but it doesn't guarantee that the foam, because the microbial community makes a lot of difference. And I think that gets at why does it So a few last few points for you, foam is a serious issue. It's rooted in the biology of the manure pit, and we know come and go? Some years we we don't have it, and then some that. So there's things we can do right making sure that we're trying to keep the carbon low in the pit. And that could be years it comes back. Well, it's, it's related to that microbial adjusting feed ingredients. It might be getting into systems community structure and and there's a lot we don't that do some solids removal. It might be as simple as, what's the best we can do to make sure that we're agitating well and understand there. We probably can say things like, as the get as many solids out as possible every year. We should methane production in the manure gets more active, fires up, we be monitoring the foam levels in our barns. Look for early warning signs. So look for that crust. And if you have that have more risk to it. And should the we tip over a threshold or a crust, if it breaks and you start to see bubbles, that's probably a sign that we might move towards a foaming barn if tipping point, maybe we get foam. But that's really what's we don't make an intervention. And then the last one is really respecting the risks. I think we've seen foam for a while. I happening there. We're sitting on the cusp of we might be one think, from my perspective, we've probably done a better job thinking about safety when we have foam, but there are still microbial community we want might be the other one, and issues where people get hurt. We have a barn fire, an explosion, one's going to lead us to foam and one won't. So if we really so we need to be mindful just that it's something that we've seen in past years. We still need to be respectful of the wanted to try and get microbial based treatment structures. risk that it has before us. So with that, do you have a show handout for today. I encourage you to take a look at it. It It'll take a lot more effort to sort of figure out where those sort of walks you through some of what the science behind the foam is and then gives you some best tips for some of those tips and balances are. But if we want to understand the basic treatments, practices and ventilation during manure risk profile and what's really the mechanisms behind the foam, agitation. So with that, thank you for joining us again today. If you have questions about foam, feel free to contact me, I think think we've done that. and I'm happy to try and address them. Thank you for joining this installment of Talkin' Cap. Be sure to take a look at the show notes on our website, for links and materials mentioned in the episode, for more information, or to get in touch, go to our website, www.extension.iastate.edu/immag. If you found what you heard today useful or it made you think, we hope you subscribe to the show on your podcast app of choice, signing off from a job that sometimes smells but never stinks. Keep on talking crap.