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

Episode Transcript

(00:00):
Hello and welcome to Talkin'Crap, a podcast by Iowa State

(00:09):
University Extension andOutreach. This institution is an
equal opportunity provider forthe full non-discrimination
statement or accommodationinquiries, go to
www.extension.iastate.edu/legal.
In this podcast, we discussinsights into the science
technology and best practicessurrounding manure management.

(00:30):
Our objectives are to buildawareness about the challenges
farmers and the broaderagricultural industry face
around manure and to demonstratesolutions and areas of
in the ag and biosystemsengineering department at Iowa
innovation.
State University, and todaywe're talking about manure foam,
something that's caused barns inthe Midwest to explode.

(00:53):
Researchers like me to do a fairamount of investigation or a
deep dig into what's happening,and also just provide safety and
environmental concerns for pigsand people. So what I really
want to talk about today is,what is foam? What do we know
about why it's happening? Whatwe think we've learned where
we're going and what you shoulddo about it when you see it? A

(01:15):
few things to remember, foamappears to show up seemingly
randomly, but there is somestructure about why it's
happening. It's a major safetyhazard. So we have had barns
explode or fires occur when thatespecially when that foam is
disturbed, when then there issome sort of spark or a treating
event to let it on fire. Eventhen we don't have that

(01:39):
explosion or a spark occur, it'sstill a safety concern because
there is a lot of gas trapped inthose bubbles. And should we do
something to break a bunch ofthose bubbles rapidly? We get
quick gas release, and that'smostly methane and hydrogen
sulfide. And while I focusmostly on that explosion risk,
with the hydrogen sulfide inthere, there's some air quality
risks for pigs and people, andthen it's just a management

(02:02):
hassle, right? If the third orhalf of your pit is taken up by
foam, rather than space that wecan use to store manure, there's
more pressure on when we need toapply having to get that barn
out of the pit. What am I goingto do to make it to my next
application window real quick?
What we're going to try and talkabout today is just the science
behind foam, the risks andmanagement options you can take.
If you do have any questions, Iencourage you to either hit me

(02:25):
on Twitter, send an email [e-mail], or just reach
out and talk to me about thefoaming concern.
A little bit of background. Whatis manure foam? Well, starting
back in somewhere around 2010,2012 we started to see this
gelatinous goop on top of somemanure storages. This goop would

(02:47):
catch bubbles of gas, and wecalled 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 moreof a froth like you get when you
blow bubbles in milk, tosomething that looks more like
the consistency of Cool Whip,only a dark brown and smells

(03:09):
like manure. So there is somevariation in that, and we'll
talk a little bit about why andwhat it means and how to think
about it. But we started to seeit roughly in that time period,
and people started askingquestions 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 thishappen? Or, man, I have a whole
barn and that half is foamingand this half isn't. Come on.

(03:33):
It's all the same. Why is it sodifferent between the two? And
what can you scientists tell meabout it, or what should I be
doing about it? So we got fundedfrom Iowa Pork Producers. They
funded both Iowa StateUniversity, the University of
Minnesota and the University ofIllinois, to start doing some
work on what are the causesbehind foam, and hopefully,

(03:53):
eventually, what are some thingswe can do to mitigate some of
the challenges that come alongwith foam. And like anyone would
do, the first thing we did is wesaid we're going to sample this
problem away. And what I mean bythat is we got something like
100 barns. We went to them on amonthly basis, and we got a
whole bunch of manure samples,essentially enough manure
samples to the point where, whenI'd get back to Ames and look at

(04:15):
my cooler, I'd make a jokeabout, well, there won't be any
foam in that barn. We've movedit all into the cooler here so
that we could study it. Andcertainly that's not true, but
there were quite a few samples.
Every time we went to a farm, wetry and get anywhere from two to
four samples between how deepthat manure is to really
understand is there a spatialdifference with depth? Sometimes

(04:39):
trying to sample two barns at asite, especially if we had one
barn that was foaming and onebarn that wasn't. But really
trying to get a good assortmentof both foaming and non-foaming
barns at any month. So we didthat for about a year. Got a lot
of data, and one of the thingsthat was really helpful for me
is just observing those barnsurfaces throughout that year on
how they change from not foamingto foaming, or they'd get a

(05:01):
crust.
And I know we all can look atour manure, but I don't know
that we all do look at it everymonth and really pay details to
what's that surface is lookinglike. And that was one of the
things we recorded every time wewere there, depth of manure,
depth of foam, thickness ofcrust. And just looking at them,
you'd sort of get this trend,because we paid attention to the
same barn every month comingback, opening the same pump out,

(05:22):
looking at it was what washappening. And one of the things
that we saw would often happenis right before it foamed, it
would get a crust. Butunderneath that crust, if you
broke through it to get yourmanure sample, there'd be this
light, small, foamed bubblematerial. And that was really an
indicator that the barn wasprobably going to be foaming in
a month or two when you cameback, if there wasn't an

(05:44):
intervention made. So it soundssimple, it sounds dumb, but it
was actually relativelyinteresting to me, and it made
us start asking questions like,Well, is it getting a little
crust on it because that'sacting like a cork on a
champagne bottle, holding someof the bubbles in and then it's
just interacting with stuff atthe surface to make this foam,
or is the crust necessary? Andit's not always necessary. We

(06:05):
saw barns that never crossedfoam, but it did often have a
trend where we'd go through thisalmost foaming, this soft,
moist, sort of bouncy crust, andthen we'd get to foam. Now some
barns would get that crust, andnext time, when you come back,
it'd be a little harder and alittle thicker, and when you
broke it, there wouldn't be anysign of that gelatinous group
goop right below the crust, andthose didn't turn into foam. So

(06:26):
what's the difference? Why wassome happening and some not? And
we'll try and talk a little bitmore about that.
Alright, I wanted to start outby saying a couple things here,
but we're going to talk aboutmanure foam, and I really want
to talk about different types offoam. First I wanted to talk
about trying to blow bubbles inwater, milk, whipped cream, and

(06:47):
then what meringue is, andtrying to talk through a little
bit about what those differencesare. So when you take water, and
I have a four year old daughterjust learning how to swim, and
one of the things they wereteaching her was blow bubbles in
the water, right? It's atraining exercise to get used to
putting your face in in thewater. And kids find it fun,
right? Bubbles are glorious andfun to play with, so she took to

(07:09):
it and puts her face in thewater and blows some bubbles.
And when you watch it, it formsbubbles, and you can see them
momentarily, but they breakreally quickly, right? And
that's sort of the no fun ofblowing bubbles in water and and
it happens because the surfacetension of water is relatively
high, right? So there'sessentially, it's so high that
it puts enough pressure back onthe air in there that it pops

(07:30):
the bubble, and there's nostructure to help hold the
bubbles together, and you getbasically an instantaneous
collapse of the bubble. So youcan blow them, but they don't
stick around. So water's like aparty that ends before it starts
or ran out of your favoritebeverage of choice way too
quickly. And there's a fewthings we can take away from
that. The first to me is surfacetension is really important, and

(07:52):
the other is that nostabilizers, no foam, so it
takes a few things to makefoaming happen. Another thing
that we might think about ismilk. And as a child, I loved
blowing bubbles in milk. It wasa fun pastime, and one of the
first things I noticed is whileI could never get enough bubbles
in water to make it overflow theglass, if you're playing around

(08:13):
with your milk, you certainlycan, and you better not do that,
because your mom will tell youall about it. So what makes milk
foam when water wasn't well,there's a few things in it.
There's proteins, and they mightprovide some state, like
stabilization to the foam. Butthere's also at least a little
fat and milk, and that fat is asurfactant. So that surfactant

(08:34):
stuff essentially helps lowerthe 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 inthere, the rubber band doesn't
pull as hard, and that helpsbubbles stick around a little
bit longer. Now that foam isn'treally stable either, you might

(08:55):
enjoy some froth on your coffee,and that's probably what we
should call it, as froth insteadof foam. It you can make the
bubbles. They're there. Theyhang around a little bit, but if
I come back tomorrow, they'reall going to be gone. And that
probably isn't what I'd call agood stable foam, but more of a
froth that's there for a littlewhile. The third one I wanted to
talk about is Cool Whip. AndCool Whip is sort of an

(09:16):
engineered foam, right? It's,some people would say perfect,
because we cheated andengineered it. But essentially,
we're adding emulsifiers andgums. You whip some air into a
fat and water base and throw alittle sugar in there to make it
taste good, and it will hold itsform, maybe not indefinitely,
but for quite a while. Andespecially if you buy the store

(09:36):
bought Cool Whip, it's a long,long time. And if you make it
from whipping your creamyourself, maybe not quite as
while, and you can sort of seethe 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 thatconsistency, whereas, if you
whip it yourself, you're gettingair entrained in it, but it
still doesn't have thatstability and eventually will

(09:59):
moreit pops right. Essentially, the
break down.
And then there's everyone'sfavorite version of a foam,
maybe not everyone's, but it's apretty tasty one meringue on
your lemon meringue pie. Andthat's the one that, to me, at
least from the science andchemistry that we sort of
uncovered in manure foam iswhere we get to. So generally,
there's a lot of water inmanure. So you might say, Well,

(10:20):
I think pig manure should belike water. It makes bubbles and
they break instantly andoftentimes. That's true, but
there's other stuff in manure,right? There's fats, oils, some
proteins, maybe a fewcarbohydrates, or at least a
fair amount of fibers, and assoon as we have those fats and
oils in it, we've maybe movedmore towards that milk regime,

(10:42):
those bubbles happen becausewe've lowered the surface
tension from the foam or fromfrom the having the fats and
oils in it. Now, in no case arewe probably like Cool Whip
because we haven't addedemulsifiers and things like that
to make the foam work. We needsomething that's more natural,
and that's why I tend to think alittle bit more of that
meringue. But when you thinkabout what

(11:14):
more stable as a fluffysubstance that's on top of that
delicious lemon. The other thingthat we do is we add sugar, and
that increases viscosity andhelps stabilize it further. So
when you think about, let's say,in this case, rather

(11:47):
pressure inside is big enoughthat the rubber couldn't hold
itself. And in some ways, that'swhat's happening naturally.
There's this structure probablyfilled with proteins, maybe some
fats and oils around thisbubble, and if we get too thin,
so either the bubble gets toobig, or water, in this case,

(12:09):
drains away from that material,the bubble wall will get thinner
and thinner and thinner, andeventually it goes pop right and
opens up and lets material out.
So if you can do things to makeit drain more slowly, those
bubbles will be more stable andstick along around longer. So in
meringue, we're adding sugar tothat egg protein mixture, and

(12:29):
that causes a couple things tohappen. It causes more water to
stay in the bubble structurelonger, because we've increased
the viscosity, we've made itthicker so it drains more
slowly. So that's sort of a foodchemistry of what's happening
and how you can make differenttypes of foams and why they
behave differently. And I wantedto do that because I think they

(12:52):
give us a conceptual frameworkto how to think about manure
foam. So when you're making thatsource. We need some tension,

(13:17):
surface tension reduction,have a conceptual framework, but
we said, well, these are thethree things that foam really
needs. How can we think about itin terms of the science of foams
that we know. In this case,manure ended up, foaming manures

(13:39):
end up having basically the samethree elements, right? So gas
supply, in this case, it'sgenerally methane from microbial
fermentation. They need somesurface tension reduction. And
it turns out there are oils inmanure, right? So while pigs or
people, or all animals do arelatively good job of consuming
oil. Some oil is passed throughand ends up into the pit, and

(14:02):
microbes will break down thosethings into sort of short,
medium and long chain fattyacids. Those fatty works

(14:29):
tasty muscle. But it's in thiscase, though, there's the
protein rich particle thatinteracts with some microbial
produced poly-liposaccharide,and it makes these small, really
viscous particles, or, as I liketo call it, the goo, that
surrounds the foam holds ittogether, and really provides a
lot of that stability. So justlike a meringue, microbes in

(14:50):
manure produce goo that trap thebubbles, hold the bubbles
together, except instead ofmaking a delicious dessert, it's
setting the stage for danger.
All right, so we did a fairamount of work on foam, and I'd
like to tell you it was allreally well thought out,
intelligent work. And some ofit, at least was, but some of it
was, at times, throwingspaghetti at a wall and seeing

(15:11):
what would stick. So the firstthing we did, we said, we're
gonna go get all these manuresamples, and, well, we have to
measure them for something. Andwhat should we measure them for?
And we said, well, maybe knowingsomething about the types and
number of microbes in the manurewould be useful. And then we
said, well, we know surfacetension, viscosity all play a
role, so we should measure thosethings too. And then we said,

(15:32):
well, we know stuff aboutmanure. We'll just measure
standard manure chemicalproperties and see what those
can tell us. And finally I said,Well, I'd like to measure how
quick is it making methane? Arewe sure that these pits just
aren't making more bubbles? Andthat's why they have foam,
because as a kid, if I wantedmore bubbles in my chocolate
milk, I just blew a littleharder and and all of a sudden
they appear, right? So, we gotall these manure samples, we'd

(15:58):
bring them back to the lab, we'dset them on a lab bench and
incubate them at roomtemperature for about three days
measure how much methane theymade. And one thing that jumped
out at me after one month ofdoing this and then two months
of doing this, is manures thathad foam making methane
significantly faster thanmanures that don't have foam.
You might say, Well, that wasintuitive. Anyone could have

(16:18):
known that. Maybe, maybe youcould have guessed that. Maybe
we should have guessed that, butit was nice to have data behind
it, and what we found is, onaverage, foaming manures were
making methane three timesfaster than those that weren't
foaming. Now, every barn thatmade methane more quickly didn't
meringue, we need egg whites orthe protein, we need a sugar,
necessarily have foam, but itwas a pretty good indicator of
which ones were foaming or whichone weren't. And at first we

(16:40):
said, All right, that tells ussomething, really, it's making
me this methane more quickly,and that's part of the equation,
right? But more than that, Icame up with this idea. Well,
maybe it's drying stuff to thesurface. In the wastewater
treatment world, there's thisprocess called dissolved air
flotation. Essentially, it'sjust like recovering stuff from

(17:01):
a shipwreck, right? You takeyour raft out there, deflate it,
lower it down, and then we putall these, essentially balloons
into whatever sunk below intothe ocean. We blow them up with
some sort of gas that's lighterthan water. And next thing you
know, we've got enough buoyancyto float. In dissolved air
flotation, you're doingessentially the same thing.
You're putting air into thisliquid material, trying to get

(17:24):
it to stick to whatever youwant, to remove, oftentimes,
small solid particles, and itcauses those particles to float
to the surface. So what I'mtrying to say is, yes, higher
methane production rates lead tomore bubbles because, well,
there's just more gas. But thesecond thing they're doing is
sort of acting like thatdissolved air flotation system,
in this case, a dissolvedmethane flotation system. And

(17:46):
those methane bubbles aresticking to small particles in
there, acting like flotationdevices and dragging those
particles to the surface. Andthat was sort of a new and
interesting finding. And whatthat implied to me is, well,
there's two reasons that methaneis important. It's not just that
it's high. It's that it has toseparate this goo that would

(18:08):
generally break down into themanure, up and onto the surface.
And when you looked at the typesof things that were going on,
and a great chemist, SteveTrabue, who works at ARS here in
Ames, started doing somechemical analysis of that goo,
right? We tried to do it forboth non-foaming manure, foaming
manure, and then the foamitself. And essentially, what he

(18:31):
found is that thispoly-liposaccharide wasn't
really present anywhere exceptin the foam. And there's two
reasons that could happen. Oneis, well, there's some micro
about the surface just makingthis special goo that really
matters to us. And while thatmight sound like a great theory,
and it could be true, we didn'treally find any data that

(18:51):
supports that. Instead, itprobably is something that's
made in the manure, gets brokendown by some other microbial
system relatively quickly andeaten up and consumed unless it
makes it to the surface wherethere isn't as many microbes to
be working on it, and it gets tostick around and starts to
accumulate. And it's that stuff,that goo, as it gets to the

(19:11):
surface, that's really trappingthe gasses and starting to
concentrate them at at dangerouslevels.
Okay, so a couple other things.
I promised a little discussionon on surface tension, because
we said that's important. And ifyou've ever tried to blow
bubbles with your kid and makehomemade bubble solution, you've
probably taken water add alittle bit of essentially,
detergent or dish soap, right,to lower that surface tension

(19:33):
down, and all of a sudden youwent from not making bubbles
because the surface of tensionwas too high to making bubbles.
But the truth of that matter isyou can keep adding surfactants
and lower the surface tension alittle further and a little
further and a little further.
And if you do that, you sort ofturn that rubber band or that
elastic into something with noelasticity left, sort of your

(19:56):
worn out pair of underwear,right. They just don't come back
to their original form. And whatwe actually see in manure
systems is that foaming manuretends to have a higher surface
tension than non-foaming manure.
And at first, I was like, thatdoesn't work with the theory of
what we thought at all. Wethought we needed to lower the
surface tension. But what wereally, I think, in the end,

(20:19):
decided, is that the surfacetension is generally low enough
in manure that if bubbles form,they pop relatively quickly
because there's no elasticityleft to hold that bubble
together. And what we saw isthat the surface tension in that
manure was just reallyproportional to how many
volatile fatty acids were stillleft in that manure. So short
chain volatile fatty acids aresomething that microbes eat,

(20:41):
generally, relatively quicklyand turn into methane. So in
that foaming manure, one of thethings we see is it's making
methane more quickly, and it iskeeping the volatile fatty acid
concentration lower. So there'snot as many of them, the surface
tension comes up, and all of asudden we're in that ideal
bubble forming range, ratherthan too easy to break bubbles.

(21:03):
So it wasn't what we expected,it wasn't what we were looking
for when we just startedmeasuring surface tension, but
it was a useful thing tomeasure, because it helped us
understand where we were inrelation to forming bubbles in
the system. Now I don't want totalk about that one too long,
because I don't think it's oneof the two main things that were
changing, I think that gasproduction, or the gas source,

(21:24):
was really important, and thenthe other one that's really key
is that still foam stabilizationmethod, mechanism. And here we
got a little lucky. We werestarting to get a little
frustrated not understandingwhat was happening, but we
invented this thing called thefoam stability test. And by
invented, I mean we ripped itoff from sort of the beer
industry, where you pour a beera certain way and see how much

(21:45):
head it makes and how long thathead lasts. And here we said we
could do that with manure. We'lljust blow some air through it,
and then start measuring howmuch foam it made and how long
that foam lasts, and try andrelate it to things. And we did
that, and we saw that foamingmanures were vastly different
than non foaming manures. Andagreed. We knew that was going
to be the case, or at least hadstrong feelings that that should
be the case. But one of thethings that let us do was say,

(22:08):
All right, we're just going tothrow some stuff in there and
hope for the best. One of thoseeight things that I throw in
probably will make foam nothappen, and then we'll be in
great shape. And I think ourlucky breakthrough actually went
the opposite way. We showed upand 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 awood with high tannin, and

(22:30):
that's sort of where tannincomes from. It's used to tan
hides, but tannins naturally arein a bunch of different things.
So we had this tannin, andpeople had shown that by adding
tannins to manure, you can lowerthe rate that the microbes are
making methane, mostly becausethey don't like tannins. And we
said, All right, we're going todo that. We're going to throw it
in this manure sample, and thenwe'll blow some air through it,

(22:52):
and we'll let this other onethat we had tannin through sit
two weeks, and then blow someair through it, we'll measure
how much methane it made inbetween, and start saying, like,
if we reduce the methane, doesthat 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 wasfoaming and a manure that wasn't
foaming, and we did the manurethat was foaming and yep, it's

(23:15):
still foamed. And I was like,okay, that shouldn't have done
anything at time zero anyway.
And we did it again with themanure that wouldn't foam after
we threw the tannins in. Andwe're like, what the heck it
made this foam that it didn'tbefore, and that foam was really
stable, really stable in that itwould have a half life of about

(23:35):
three days. So it took threedays after we made it for half
that foam to break down. I waslike, What the heck is going on
here? I ran down a floor to talkto Steve, and we started talking
it through, and we're all like,this is really strange. This is
really weird. What happened? Andthen Steve said, well, tannins
are known to interact withproteins, so maybe it's just
those proteins that are bindingwith it to make the foam stable.

(23:58):
And we're like, All right, yeah.
And then we started to do somereading, and it said that
oftentimes protein foams lookgreat. And I was like, yes, foam
and barns look great, but itdoesn't quite answer the
question, right? What is bindingthese proteins in manure in
reality, to make them sticktogether? And do all manures
have these proteins? So Stevedid some great work on the the
proteins in the foam, andunfortunately, found their kind

(24:20):
of corn protein. And that'spretty much ubiquitous, right?
We're always going to have cornprotein. 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 reallystarted looking for that
poly-liposaccharide. And I'dlike to say he was looking
specifically for it, but we werelooking for what the goo might
be, and just trying to get achemical breakdown of it. But
what he found was that thispoly-liposaccharide probably is

(24:42):
interacting with the proteins alot like what we get from
meringue, to make that matrixand form some stability. And
that all started because we gota little lucky, right? We were
just throwing stuff in, andhappened to see a positive
result.
So I think that tells us a lotof where the the material was.
The other thing I will mentionis one thing that I think we got

(25:05):
a little lucky on too, was Idecided to measure particle size
of foaming manure, non foamingmanure in the foam. And one
thing that was weird was thatfoam was filled with 2 to 25
micron sized particles, which isessentially a silt sized
particle or a fine silt, soreally small particles, and you
could sort of look on the foamand know that it was filled with

(25:27):
that style size of particles.
It's super solids rich. So thatmade sense to us. But one thing
that we kind of got a littlelucky on was we saw that the non
foaming manure had moreparticles in that 2 to 25 micron
range than the foaming manuredid, and that's really where we
came up with that dissolved airflotation system, where it was
attaching to fine particles andbringing that microbial goo to

(25:48):
the surface.
So all that to say, I think wegot a pretty good understanding
of the mechanism of why are wegetting foam? What's happening?
Well, it's more methane. Itfloats this microbial goo to the
surface. It interacts with thechurn and makes this protein.
And next thing you know, youhave sort of a meringue, a
bubble filled meringue on thesurface of your manure pit. Now

(26:09):
there's additional questionsthat aren't answered from that
right, like, why does this pitfoam? And that one doesn't when
it's the same pig, samemanagement, same feed system.
So the last sort of leg on thatwas we did some feeding trials,
and we measured microbialcommunity on lots of manure.
When we did feeding trials, wecould tell a few things. One in

(26:30):
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 theirnon-foaming counterparts. Now,
in our studies, when we startedwith clean manure tanks, we
never turn that methanepotential into actual methane

(26:51):
production. It would make somemethane, but they really didn't
develop the microbial communityto be vastly different, but it
still was sort of like startinga campfire. The wood's there,
we've added kindling. All weneed now is the match. So that
was one of the things that Ithink was key from the feeding
trials, just understanding sortof, how do different diets
influence that carbon potential.
But we also saw that differentfeed ingredients were capable of

(27:15):
changing the microbialcommunity. Unfortunately, we
only saw that half of themicrobial community was
influenced by the feedingredients that we're using in
any given study, and the otherhalf was, who knows what, all
the other stuff that we didn'thave control over, maybe how
much water an individual pig wasdrinking, the temperature the
manure was at, maybe just whatwas ever in the microbe of the

(27:36):
pig's gut before we started. Andthen you can only modify it so
much, but there was still a lotof variability. And I think that
sort of answers the question ofwhy one barn might foam and one
doesn't because it is microbialcommunity related. And from all
our microbial sampling, we gotdistinct differences in the
microbial community of foamingmanures compared to non-foaming

(27:57):
manures. So we can say we'redifferent, and you could say,
Well, you got a super bug inthat foaming manure. No our data
didn't really indicate that. Thetypes of bacteria were present
in both manures, foaming andnon-foaming, but the percentages
of different types changedgreatly, right? So the community
structure was different. So goodnews, no superbug. Bad news,

(28:19):
it's different for some reason.
And well, it's probablypartially related to feed, but
it's partially related to allthose other things. And one of
the things we saw it waspartially related to is what
type of microbial community youalready had. So if you had
something that was wellestablished, it tended to be
harder to change it to a newtype of microbial community. So

(28:41):
if you have a non-foamingmanure, there's probably some
resistance to staying anon-foaming manure. Your manure,
microbial community, doesn'twant to change unless we do
something to really causechange. And what I mean by that
is, when you cause adisturbance, like agitating your
manure, pumping it out, maybethere's a chance to recultivate
that manure, but it might settleback to where it was, right? It

(29:01):
has a tendency to settle backtowards where it was, unless
there's a management change.
Same with foaming foamingmanures, right? If it was a
foaming manure, it probablywants to stay a foaming manure,
unless something happens tochange that community structure.
And from a treatment standpoint,that's both good and bad, right?
If you have a non foamingmanure, you're like, all right,
I'm living the good life, I'llprobably stay non foaming, but
there might be time periodswhere I should worry a little

(29:24):
more. Essentially, right afterpump out. If I'm a foaming
manure, it says, well, it mightbe hard to change it, because my
community structure is alreadythere. The community is working
relatively well together, sounless there's some event to
really knock them off course, itmight be hard to change, which
is one of the reasons why wesay, if you have a foaming
manure and have had a foamingmanure before, that's probably a

(29:46):
good time to consider treatingyour pit right after you pump it
out, because it's most prone tobeing changeable at that point.
There was a couple otherquestions, like, why us? Why
now? when we started seeingthese problems in the Midwest,
and there's a couple things.
One, we probably started feedingmore high fiber diets.
Essentially, DDGs got popular.
They got cheap, and that meantmore micro food. Another thing

(30:11):
that we tended to see at thattime is that embedded fats in
the manure are less welldigested than fats are added
back. So those DDGs had someoils embedded in them, and while
pigs do a pretty good job ofbreaking up that oil and
digesting it, more of it waspassed through because it was
embedded. These days, we tend tosee people doing a better job of
separating oils and then whereappropriate, adding them back to

(30:32):
the diet, and that improvesdigestibility. The other thing
that was happening at that time,especially in the Midwest, was
we were really improving waterconservation in barns. So we saw
a lot of people switching to wetdry feeders, less manure per
pig, same amount of manureexcreted per pig in terms of
solids, just less water endingup in the pit. And there's sort

(30:56):
of this ideal range for makingmethane from manure. It's
probably somewhere between like6 and 10, 12% total solids
content. And by getting thosewater conservation measures in
place, we started to thicken ourmanure, and we were thin, and
we're starting to move higherand higher on that ideal, closer

(31:16):
to ideal methane range, right?
So we started to get to thebottom side of that. And then I
think with time, we've gottenmaybe 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 tobe ideal for methane production,
and that's probably reduced ourpropensity for foam, in many
cases, not that we can't foam.

(31:38):
The microbes are very adaptable,so even around that higher side,
there's still some opportunitiesfor foam. But I think that was
one of the reasons at that timewe saw it more prevalently in
the Midwest, and maybe we sawsort of that amount of foaming
come down for a little while. Ithas a lot to do with sort of
being in that ideal range andcultivating that microbial
activity. I know I've started tosee and get a few more phone

(31:59):
calls from foam, maybe furtheraway from Iowa. So I'd like to
think we're a leader in theindustry, and we were a leader
in pursuing that, and maybe someof the areas are starting to
catch up on some of their waterconservation methods, and
starting to see some of thatmanure get more carbon rich and
start to get to maybe that areawhere it has more chance for

(32:19):
foam. And that's both good andbad, 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 thefertilizer. So it makes a lot of
sense that people would movethat direction.
Okay, I wanted to talk a littlebit about why foam is dangerous.

(32:40):
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 foamitself is way above that range.
But when you break thosebubbles, start diluting that
methane in the air in the barn,all of a sudden you are in that

(33:01):
that explosive range. So thingsthat cause sudden collapse of
the foam release a lot ofmethane at once. Agitation,
maybe washing your barn, becausethe water falling through breaks
those bubbles. That's when wereally get to those dangerous
gas release and have potentialfor explosion. So anytime you're
doing that, really takeattention to ignition sources,

(33:21):
heaters, static electricity,electrical arcs, welding,
smoking, things of that nature,right? Anything that gets into
that foam will start to breakthe bubble. It'll start to burn
them. If we've released a lot ofthat gas all at once, that's
when we get the explosion. Iknow a few people have told me
I've dropped welding slag in thepit. A be really careful about
that. If you have foam, beextremely, extremely careful.

(33:42):
Even if you don't have foam, youcan sort of get a fire down
there at the pit, and they'llsay, Well, I saw it burn across
the barn. And I always think itwhen I hear these stories. I'm
glad I wasn't there. I wouldhave panicked. But that foam
itself, when you started on thefire in the pit, it does tend to
be too high to get an explosion.
It sort of burns across thatfoam. And it does get hot, it
does get worrisome or dangerous,but since the bubbles are

(34:05):
contained, it sort of breaksthem in a controlled pattern as
it moves across. And I thinkthat has helped, in some cases,
avoid that big bang or bigexplosion, if we've done
something like started topre-soak our barn, to wash it
while we had foam, and then weget that same spark, oftentimes
from a pilot light, that's whenwe've tended to see more of
those, those types ofexplosions. So there are a
couple things you can do. One,try and avoid those risky

(34:28):
activities, right? If we arebreaking foam, make sure we've
done what we can to minimize aspark occurring. If you do need
to weld in your barn, put down aslag mat to catch the slag.
Don't let it fall in the pit. Ifyou have foam and it's a problem
and you're going to do somethingto sort of break it, we
definitely need to beventilating. If all the pigs are
out of the barn, we still needto be running minimum

(34:49):
ventilation. I know, especiallyin the winter, we want to keep
the barn warm. It's tempting toreally turn those fans down when
we don't have pigs in the barn.
We do tend to see foam for moreoften and and you could say,
Well, is it a change? Because wesuddenly stopped feeding the pit
new manure, and maybe, but it'sprobably just that we no longer
have manure, feces in urinefalling through, breaking some

(35:11):
of those bubbles, so the foambuilds up faster than it was
being broken by stuff fallingthrough. And then if we do get
something happening, like aspark, well, there's been more
methane that's there to in thefoam and in the barn to get us
to some of those explosivelevels.
So what are some things we cando? What should we be thinking
about in terms of foammitigation? Well, there are some

(35:35):
prevention strategies, and Iknow one that we don't have
necessarily a lot of controlover, it's often dictated to us,
either from the integrator orfrom prices of feed ingredients,
is thinking about that feedcombination, how you're feeding
your pigs. We know that feedinghigher fiber ingredients, things
that are less digestible to pig,puts more fuel into the pit. It

(35:55):
puts more carbon into the pit.
So you can think about, is therea way I can formulate rations to
sort of adjust that to reduce myrisk, and the answer might be
yes or no, right? It might beone that you could do something.
It might be something where itdoesn't feel like it's
achievable in what you havecontrol over. And I certainly
understand that.
The other thing to think aboutis solids management. Microbes,

(36:19):
especially anaerobic microbesare really slow growing only
about five to 15% of the energythey eat actually gets turned
into microbial biomass. The restis turned into carbon. And what
that means is, if I get rid ofthem all, it takes a long, long
time for them to grow back. Andoftentimes these guys are

(36:40):
hanging out where the carbon is.
So if you have a sludgy layer inthe bottom of your pit, well
there's more microbes in thatlayer generally, right? So if
those solids are like sludgelagoon, where all the volatile
solids have been eaten, Iwouldn't say that's true, but
when we think about a deep pitsituation where we do a decent
job of getting it worked upevery year, and those styles say
somewhat fresh, that probably istrue. And that means one of the

(37:03):
things that you can do, even ifit won't solve the problem it
has the potential to help, istrying to make sure we do
agitate thoroughly, get as manyof those solids, especially
those settled materials, out ofthe pit every time we're
agitating, because it gets ridof the inherent microbial
community that was there, and itcauses an opportunity for
change. It also gets rid ofcarbon that was their food
source, right? So if I take awayall your food, you're not going

(37:25):
to stay happy. You're probablygoing to try and move along. And
while these microbes can't getout of the pit, they won't be as
happy. And and some othermicrobes that are more adapted
to survival and thriving at low,lower carbon contents of the
manure probably will take overinstead of the ones that we tend
to see when we get to thosehigher ones. So I can't tell you

(37:48):
that getting rid of those solidswill solve all your problem, but
it is certainly a way to help.
It's something that we see inanaerobic digestion right there.
We're often trying to hold on tosolids or recycle solids to keep
the microbes in the digester sothat we can increase methane.
And here we're really trying todo the opposite.
effective.
people try using some water havean

(38:09):
There are some other approachesto treatment, and rather than
being maybe more systemapproaches, they're more
tailored to specific treatments.
So there are things that we canadd. We talked a little bit
about surface tension and said,well, surface tension of foaming
manure is higher thannon-foaming manure, so if we can
lower the surface tension alittle bit more, will not
formthose bubbles will breakmore quickly, and

(38:32):
oil lowers the surface tension.
I won't have that foamingcapacity, the foam stability I
had before bubbles pop reallyquickly. So that sounds good,

(38:56):
but if you wait two weeks, threeweeks, four weeks, that crop oil
starts to get broken down bythose microbes. And one of the
things that we said earlier isthat as we break down oils,
especially, we think we'remaking this poly-liposaccharide,
and that all of a sudden makesthe foaming situation worse,

(39:53):
that's really high in ammoniaand hydroxide, and it sort of
has this soapy, rubbery feel,and it's a surfactant. It helps
Another one, and the one that'sprobably become most popular is
thinking about ionophores. Soionophores are targeted to

(40:13):
reduce, essentially, methaneproduction in animal guts, and
the way they work is essentiallytrying to make it so that you
don't make acetic acid, you holdit into some slightly bigger
chains of carbon that can beabsorbed through the intestine
more effectively, and reallystopping that last step of
turning into methane. And wethink about that in animal body,

(40:34):
well, there's somewhere else forthat carbon to go. Right? The
carbon chain gets absorbed intothe intestine. The animal uses
that material to form new cellsor whatnot. In a manure pit, it
doesn't work quite the same way.
We might be able to throw thationophore into the manure stop
that methane process, or atleast reduce the rate of that
methane process for a while, butthe carbon still there. It

(40:55):
doesn't disappear. So it can belower that surface tension
again, and it can be effective,effective for a while at keeping
the methane production ratedown, but it probably more so in
the long run is more effectivebecause it changed the microbial
community. Some other microbeswho wouldn't have naturally been
there and been part of thatdegradation pathway, get to be
more dominant in that pathway.

(41:16):
They would have been in themanure to start with. But rather
than being 3 to 5% of thepopulation, all of a sudden
they're the dominant 20, 30% ofthe population. That's really
doing that step. So we're justchanging the type of microbes
barn, maybe that's an option. Ifyou're looking for
that can do that. And I knowsome that people have used are
narasin, which is Skycis, that'sa pig additive. Some people have

(41:37):
used romance and all of themyou're trying to put in at
roughly five pounds per 100,000gallons of active ingredient. I
think if you've had a foaminghistory in the past, doing that
right after agitation or pumpout makes a lot of sense,
because you're trying to changethe microbial community. If you
find yourself in a situationwhere there's a fair amount of

(41:57):
foam in your barn, I like tothink of that as six to eight
inches. It's a good time totreat if you have that foam, you
need to make sure that you'regetting the product down into
the manure to be effective. It'sa powder, so if you just throw
it in and it gets hung up on thefoam on top, it's not going to
help us out. So if you take thatmix, it into a bucket of water,

(42:18):
spread it out through the pumpouts, we've tended to have more
luck in terms of treatment.
And then the final thing that Ihave seen people consider or try
is really treating that protein.
And I know I said it's a cornprotein. It's ubiquitous.
There's plenty of it in manure,but there are things that attack
proteins. So proteases are anenzyme that do it. You could buy
protease enzymes add them to themanure that's perfectly

(42:40):
acceptable. Some people havetried to use probably
help break down some of thoseproteins, depending on how many

(43:01):
proteins are in your manure,right? So you can sort of look
at what does the manure samplelook like in terms of total
I did want to just mention thatventilation, especially anytime
you're doing a treatment thatbreaks foam quickly is extremely

(43:22):
important. So if you are goingto throw in a surfactant, or if
you're going to try and water inthat ionophores by running
sprinklers because you'rebetween turns, or if you're
going to agitate a barn,ventilate, ventilate, ventilate.
The other thing I wanted to justsay is there's no single fix to
the foaming situation. There aredifferent approaches that you
can try. I think they they havevarious successes. And the truth

(43:43):
is, we don't know long term, howwell some of these are going to
work. So if I add ionophores tothe manure, I've had great luck
with it. But is there a pointwhere we've changed the
microbial community enough thateven when we're adding the
ionophore that it will stillmake methane, still float some
of this goo to the surface? Andthe answer is, we don't know.
All right, so I wanted to sum upa little bit and tell you where

(44:07):
we're at. So why does foamappear in some barns and not
others? Well, we can relate itto at least a few things. The
microbial community that isformed in that manure is
extremely important. We knowthat the diet we're feeding the

(44:27):
animal, the animal itself, isimportant in influencing that,
but it only explains somethinglike 50% of the microbial
but really, those methods areabout lowering surface tension,
community that develops. Therest is things that we don't
nitrogen and organic nitrogen,and say, you know, is it really
know yet. And that means thateven when I have two pits right
achievable to try and push moreof that organic nitrogen into

(44:48):
next to each other, same barn,same feed, same pig genetics,
trying to break the bubbles.
they might not same form thesame microbial community in the
the ammonium form? It may or maynot be effective.
manure. And I wish that's aquestion I could give you a more
satisfying answer to, but that'swhere the science is. There's a

(45:10):
lot of things that we don'tunderstand about the microbes in
manure. I think that's an areathat's that's right for more
science, and we'll continue toprobably get better at as
microbial methods have improved.
But when we think about why itis, we can sort of say, well,

(45:31):
they're the same. They'remanaged the same and and maybe
that's increased their riskrelative to barns that aren't
feeding as much fiber, but itdoesn't guarantee that the foam,
because the microbial communitymakes a lot of difference. And I

(45:52):
think that gets at why does itSo a few last few points for
you, foam is a serious issue.
It's rooted in the biology ofthe manure pit, and we know
come and go? Some years we wedon't have it, and then some
that. So there's things we cando right making sure that we're
trying to keep the carbon low inthe pit. And that could be
years it comes back. Well, it's,it's related to that microbial
adjusting feed ingredients. Itmight be getting into systems
community structure and andthere's a lot we don't
that do some solids removal. Itmight be as simple as, what's
the best we can do to make surethat we're agitating well and

(46:13):
understand there. We probablycan say things like, as the
get as many solids out aspossible every year. We should
methane production in the manuregets more active, fires up, we
be monitoring the foam levels inour barns. Look for early
warning signs. So look for thatcrust. And if you have that
have more risk to it. And shouldthe we tip over a threshold or a
crust, if it breaks and youstart to see bubbles, that's
probably a sign that we mightmove towards a foaming barn if
tipping point, maybe we getfoam. But that's really what's
we don't make an intervention.
And then the last one is reallyrespecting the risks. I think

(46:33):
we've seen foam for a while. Ihappening there. We're sitting
on the cusp of we might be onethink, from my perspective,
we've probably done a better jobthinking about safety when we
have foam, but there are stillmicrobial community we want
might be the other one, andissues 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 reallyso we need to be mindful just
that it's something that we'veseen in past years. We still
need to be respectful of thewanted to try and get microbial
based treatment structures.
risk that it has before us. Sowith that, do you have a show

(46:54):
handout for today. I encourageyou to take a look at it. It
It'll take a lot more effort tosort of figure out where those
sort of walks you through someof what the science behind the
foam is and then gives you somebest tips for some of those
tips and balances are. But if wewant to understand the basic
treatments, practices andventilation during manure
risk profile and what's reallythe mechanisms behind the foam,
agitation. So with that, thankyou for joining us again today.
If you have questions aboutfoam, feel free to contact me,
I think think we've done that.
and I'm happy to try and addressthem.

(47:17):
Thank you for joining thisinstallment of Talkin' Cap. Be
sure to take a look at the shownotes on our website, for links
and materials mentioned in theepisode, for more information,
or to get in touch, go to ourwebsite,
www.extension.iastate.edu/immag.
If you found what you heardtoday useful or it made you
think, we hope you subscribe tothe show on your podcast app of

(47:38):
choice, signing off from a jobthat sometimes smells but never
stinks. Keep on talking crap.