Fall manure best practices
University of Minnesota Nutrient Management Podcast Episode: “Fall manure best practices”
September 2023
Written transcripts are generated using a combination of speech recognition software and human transcribers, and may contain errors. Please check the corresponding audio before referencing content in print.
(Music)
Jack Wilcox:
Welcome back to the University of Minnesota Extension's Nutrient Management Podcast. I'm your host, Jack Wilcox, Communications Generalist here at the U of M Extension. In this episode, we're talking all about manure best practices and some common questions. We have three panelists here with us today. Can you each give us a quick introduction?
Melissa Wilson:
Hi, I'm Melissa Wilson I'm here at the University of Minnesota and I'm an Associate Professor and Extension Specialist, all about manure management.
Kevin Erb:
And I'm Kevin Erb, University of Wisconsin-Madison, Division of Extension based up in Green Bay. And I work with the for hire manure applicators, not only in Wisconsin, but also several of the surrounding states.
Daniel Andersen:
And I'm Dan Andersen. I'm an Associate Professor and Extension Specialist in the Ag Engineering Department at Iowa State University. I get to lead the Iowa Manure Applicator Certification training program and get to talk about all things manure.
Jack Wilcox:
Okay. Just to start out, what are best management practices for the fall manure application season?
Melissa Wilson:
Well, as we're coming into this fall, it's been pretty dry so far. Let's cross our fingers that it stays dry and we don't have to deal with really wet conditions. But one of the things as it's been staying warm that we really want to consider is getting manure applied when soil temperatures are cool in the fall. So I know we have a lot of silage coming off a lot of earlier harvested crops, and I know it's tempting to want to get manure applied, but one of our best management practices, especially for our liquid slurries that have a lot of ammonia in them is to wait until soil temperatures are cool in order to preserve the nitrogen. When it's still warm like this, there can be a lot of nitrification happening where that ammonia gets turned into nitrate and then it unfortunately is more likely to be lost throughout the winter. So one of our big best management practices is waiting until later in the fall to get it applied.
Now, if you have something like a liquid slurry, especially swine manure, we have seen some evidence that nitrification inhibitors can help. And the thing about these though is that they can only help so much. If you're still applying early, like now in September, they're probably not going to last long enough for you. If you're waiting until early October, mid-October and the soil temperatures are still warm, they might give you a few extra weeks to get you down into when the soil temperatures are cooler. One of the other things I like to stress too is we're a pretty big state, so when these soil temperatures reach about 50 degrees Fahrenheit at that four to six inch step, that's kind of what we're looking for. When we're talking about cool soils, anything below that is considered cool.
That's going to change across the state as to when we get there, of course. Up in northern Minnesota, we get there a little sooner. Down in southern Minnesota, it takes a little bit longer to reach those temperatures, especially I think now it's going to be in the 80s for a couple days here this month, so soil temperatures are still going to be pretty warm, unfortunately. Yeah, I think there's lots of other things too. I know Dan, you all have some research looking at cover crops. We've done some work too and we found that in Minnesota sometimes getting the cover crop growing is half the problem. What are you seeing down in Iowa?
Daniel Andersen:
Absolutely. I think you're absolutely right on timing is everything and manure and cover crops are a best friend, especially if you have to be a little bit early. I think cover crops offer some flexibility and opportunity. Even when manure is early, we have great evidence that if you have that cover crop up and growing, it will keep that nitrate out of the tile line from moving through the soil, holding in the soil profile, so hopefully our crops can use it later. But like you said, cover crops and timing gets to be a little difficult. We really like to try and get them on early if possible, flying them on roughly now to try and get some germination, sometimes that isn't possible. Up in northern Iowa, I have done some work where we drill cover crop on after, maybe not quite as ideal, but we've still had good luck with how It's performed as a best management practice in protecting water quality. So that is an option, especially in a year like this where we might be harvesting a little bit sooner, but they do work really well. They go hand in hand.
I know some people are worried about if I inject into a growing cover crop, is it going to hurt the cover crop? Especially with some of the lower disturbance knives and injectors we have today. Most of the time by next spring you can't even tell where you're going and the cover crops really recovered, which is great, I think. The other thing I always talk about in the fall is incorporation injection is extremely important even with solid manures, even when it's been dry, getting that manure into the soil so that the phosphorus isn't right on top is important, right? It might get a rainstorm here this fall hopefully at some point, and I know a lot of that water's going to soak into the ground, but sometimes we get a hard soil crust on top and if we get a rainstorm that can really wash off some of those nutrients unless we've incorporated it into the soil.
Kevin Erb:
And really Dan, one of the benefits that we've got coming into this year is it's been a little bit drier and you may say, "Well, what do you mean? That my corn doesn't look as healthy," but when our soils are too moist, when tend to have significant issues with compaction. And so particularly when you think about that 8,000, 9,000 gallon manure tanker and a tractor that's large enough to safely pull that, sometimes you're talking a 130, 140,000 pounds of weight going out on the field. And so really avoiding the wetter times of the fall if we can for application not only for environmental reasons, but really soil compaction and soil health.
And so I know a number of producers, particularly on the western side of Wisconsin, have really looked at some of these drier years and said, "Those are the years to get those nutrients out in some of those fields that I really worry about compaction in a typical or wetter year." And obviously if I can follow that with the cover crop to reduce the chances of nutrient loss into the groundwater, drain tile or surface water that's a real benefit that we need to be thinking about.
Melissa Wilson:
Yeah, that's a great point. The other thing I wanted to bring up too about best management practices is even thinking about calibration, if you haven't gotten out into the field yet, making sure you know exactly how much you're spreading is going to be really important. I know Dan, especially you've done some work looking at liquid manure distributors and how they work. What are some of the things that you've learned for best management practices? I know making sure your tube lengths from the distributor aren't all wonky, that sort of thing.
Daniel Andersen:
Yeah, and I think there's a couple of things that are a little easy to do. Oftentimes on the distributor we have air intakes and some use little nozzles on each line and some use just a large big air check valve. Manure is a little dirty. Oftentimes they do get plugged with salads. If those are getting plugged up with salads, you'll get a siphon and manure might suck more to one line than another line. So making sure those get cleaned out, check and make sure that they open and close appropriately, I think is a big first step.
Like you said, we worry just a little bit about are there dips in lines and is there water pooling in some of those lines, especially as we get large toolbars, some of the line routing gets a little more challenging rather than being more vertical, it gets pretty horizontal and if you have water pooling in the lines that offer some back pressure, so we don't get as much manure in those lines. And this really becomes more of an issue at lower application rates. If you're out there trying to push high gallons, oftentimes there's enough pressure to make that distributor work, but if you're really trying to dial it back, starting to get in that neighborhood of two 3,000 gallons an acre, that's when we see more of the challenges and all these little things have to get taken care of.
Kevin Erb:
From a crop perspective, I mean, am I really going to see that big of a difference next spring if one hose is only putting through half of the other one, Dan? What have you seen?
Daniel Andersen:
Yeah, I think when I go around Iowa, some years are more pronounced than others. In this last year it was really dry in the spring and we saw a lot of streaking just because we didn't have much movement of any of that nitrogen that we put in the soil even with manure and even with our commercial fertilizer. So some years it can look really pronounced. In other years it won't look nearly as dramatic, but we definitely tend to see at least some impacts. It's really easy to see if you have a plugged line essentially, right? You'll often see a big long line of yellow corn for extended periods of time. But with drones and some precision tools. We are seeing more and more evidence that there are some of this non-uniformity and some skips and misses in some of our manure fields and something that we have to be more aware of.
Kevin Erb:
And Melissa, you mentioned earlier about ammonia and the importance of trying to delay that application until things get cooler in the fall. What percent ammonia do we actually save if we inject that manure or get it incorporated right away? And does that vary between say, swine manure and what you're seeing with dairy or beef?
Melissa Wilson:
Yeah, absolutely. Some of the differences between a hog manure and a dairy manure is that hog manure tends to have a lot higher concentration of nitrogen in the ammonia form. So that one is especially critical to get incorporated into the soil. The soil really attracts ammonia, so getting it underneath the soil or mixed in with the soil really holds onto that ammonia. Versus if it's just sitting on the surface, it can just essentially evaporate chemically speaking, and it's called volatilization, but it eventually turns into a gas and is lost. And once it's in the atmosphere, you're not getting it back unfortunately.
But our slurries and our liquids are typically a higher ammonia concentration. So I think hog manure is usually roughly 80 to 90% ammonia we've been seeing, versus our dairy and beef are typically a little lower, more like 50/50 of ammonia versus... Or sorry, ammonia versus organic nitrogen. Our solids don't nearly have as much ammonia, but it's still really important to get it incorporated because just because they don't have as much ammonia, doesn't mean that the organic stuff can't convert to ammonia later in the season. One of the ones that does have higher ammonia that's a solid though is our turkey litters or our poultry litters. Sometimes you move those piles around and you get a good whiff of ammonia, it feels like it burns off your nose hairs. But that's again, it's important to make sure to get that incorporated.
Jack Wilcox:
So next question, if you are a crop farmer and you're thinking about getting manure this fall, what information do you need from the producer or the manure applicator? What are some things to look out for?
Kevin Erb:
I think that it really goes into two categories. It's what do you need before you agree to actually take manure from another farm? And then what information do you need once that manure is actually there? And so it's going to vary based on the size of your farm and other factors. But I think one of the questions that needs to be asked upfront is that if I take this manure from a large farm or from a certain operation, am I going to fall under their nutrient management plan or mine? Am I going to need to turn copies of my records over to that other producer? How does that actually work? And so really upfront kind of figuring out some of the logistics of the paperwork side of things, who's responsible for the soil test, for the nutrient management plan, who stands the cost of updating that plan or creating one if you don't have one already?
And then really trying to figure out, okay, what rate is appropriate here? And that's going to be based obviously on your nutrient management plan, on your soil test, but also on the nutrient content of manure. And I know Melissa, some of your work has really shown some real variation from one year to the next, one farm to the next based on the feed ration, based on how much precipitation is actually getting into that storage. And so knowing whether you're going to base that rate on an average of the last three years of that particular farm's manure samples or just the last one, really kind of nailing down a number of those details upfront. And I think that one of the things that I always like to say too is that you need to have a sit down meeting with the agronomist, with the manure applicator and kind of figure out where the field boundaries are, where that neighbor is that you don't want to tick off and make mad.
And so sometimes maybe if it's, you normally stay back 50 or 60 feet from that property line with a manure application or whatever distance you normally decide to and maybe you've got a very high ammonia manure, maybe it's a poultry manure, Melissa, you talked about bringing in, maybe staying back a little bit farther. Figuring out who's responsible for incorporation, when that's going to be done and then really figuring out the cost of it. And this particularly in years where fertilizer values tend to fluctuate sometimes becomes a challenge. And so before that first load of manure comes onto your property, know not only the nutrient value but who's going to be responsible for the incorporation, how the cost or the sales price is being determined and really how are you going to get the paperwork that you need after that application is complete.
Melissa Wilson:
Yeah, I would reiterate what Kevin is saying too. The other thing in Minnesota that the manure applicators will need to know in your field are where are sensitive features? So if you're down in southeastern Minnesota and you have karst that you're dealing with, sinkholes, they'll need to know where those are. They'll need to know where intake tile lines are, all of those sorts of things too because they will have to stay a certain set distance back from that as well.
Kevin Erb:
When it comes to those setbacks, Melissa, what do you typically find the manure applicators and farmers are doing in Minnesota? Are they going out there with spray paint, marking that off, putting plastic cones out there, giving an electronic map that fits into a GPS type system? What are most of the farmers and manure applicators in Minnesota doing?
Melissa Wilson:
I think we've seen a little bit of everything. Sometimes some of the smaller farms might go out and then just have big flags kind of showing where they should be applying and not applying. We've also seen people that give the maps so that the applicator can see where and where they're not supposed to be going. And sometimes it really is up to the applicator. The farmer just says put it on this field. And the applicator needs to know roughly what are the boundaries supposed to be. For instance, it's like a football field length away from a stream. If you're broadcasting and not necessarily going to incorporate as long as you incorporate, you can be a little bit closer than that, but sometimes it is up to the commercial applicator to know where those are too. But they might not know where they are if you don't tell them.
Kevin Erb:
Yeah. And really making sure that it's clear what those markers actually mean. And I know one of the challenges I've seen occasionally here is that roughly one in 10, one in 12 males have difficulty sometimes discerning colors and if you're putting a red flag in a green field, it may not be visible to that operator. And same thing if I've got a map that's got certain color hatch marks on it that may not be visible. So making sure that the person can actually interpret the maps that you're giving them, that they can see the flags or the markings that are out there really can prevent a lot of very simple problems. The last thing we want to do is have somebody get in trouble because they spread too close to a well, too close to a sinkhole because they didn't see the flag or didn't understand the map.
Melissa Wilson:
The other thing that Kevin had said that there was kind of the two things, right? There's the what do you need to do upfront and then what do you need afterwards. In Minnesota, depending on the size of the farm that you're getting the manure from, there are some requirements to keep records and to get records from the farm as well, as Kevin mentioned. A manure test is obviously really important. But again, it depends on what size of farm you're working with.
Typically their plan does not apply to your farm, but you still have to keep records about where it was applied and you still cannot apply more first year available nitrogen in the manure than is needed by the crop. So there are certain rules that everyone does have to follow. But making sure after it's applied you get some sort of map from the applicator, you get that manure test if you don't already have a copy of it and those sorts of things. It's always good to check out or check in with your local county feedlot officer or Minnesota pollution control feedlot staff to just verify that you have all the things that you need.
Kevin Erb:
That brings up an interesting point, Melissa, because I mean, obviously you don't know what's going to happen. Somebody six months from now could say, "Oh, you spread on that field and my well turned bed." How long should livestock producers and the people taking their manure actually keep those records?
Melissa Wilson:
That's a good point. I believe it's anywhere from three to six years depending on the size of the operation. So our recommendation is to keep them at least six years just to make sure all of your bases are covered.
Jack Wilcox:
So what's on the horizon for manure application?
Daniel Andersen:
Well, in some ways I think it will be more of the same. We keep seeing a lot of people need bigger equipment and we've talked about a best management practice being waiting until the soil's 50 degrees in cooling and I think that's an important one and as we look towards the future, something that while right now is a recommendation, it probably is going to be a stronger recommendation as we go forward. And that means we need to get more gallons, more tons applied in shorter windows and bigger equipment, more expedient application has been a big part of that. We continue to see higher flows of manure through drag lines. We see more people investing in over the road tanks to haul manure out to the field, to the actual applicators to keep those running and take better utilization of assets. And I think that's a trend we'll keep seeing. In parts of the US we're starting to see more investment in infrastructure to help with manure application. That could be buried PVC pipe below the ground especially to help with some of those big, big dairies.
Just generally things that will help us be quicker about getting the job done, hopefully take less setup time. The other thing we're going to continue to see is more precision get adopted. we're in a world where flow rates, good flow control is almost on every manure applicator. I think in the world of solid manure, we've seen a lot better use of weigh scales right on the spreader, GPS mapping of as applied tons or gallons. The next iteration of that is going to be hopefully some version of realtime measurement of manure nutrients as we go. I know a couple companies, John Deere, Kase already have systems on the market. I've had the opportunity to work with at least a couple of them. In some cases they work pretty well. In some places we might still need a little bit more calibration, but I think that technology's coming along and hopefully it means the next iteration is going to be rather than as applied maps of gallons or tons, we can get a better estimate of nitrogen or phosphorus as applied and make more intelligent cropping decisions based on what we think we have there.
I think the other thing we're going to continue to see is more specialized equipment. I know down here in Iowa, we're seeing a greater divergence between dairy and manure swine finishing application rates where swine finishing rates are getting pretty low, a thousand, 2,000, 3,000 gallons an acre. And oftentimes their dairy manure application rates might be 15 to 20,000 gallons an acre. When you think about getting good injection and actually achieving injection, the amount of capacity you need in the soil is vastly different between those two things and I think that might lead to more specialized application equipment.
And then the last one I wanted to mention here was we see more and more farms investing in some sort of manure treatment system, whether that be solid separation at a dairy farm. So they're working with solid and liquid manure and I think we're going to continue to see that. And in some cases it offers opportunity on the liquid side, there's less solids, less opportunity for plugging. Hopefully that will mean a little bit easier time to get uniformity with some of the distributors. But it also means we have to think about what's the availability of some of the nutrients in that solid fraction and that's a chance for both research and a chance to maybe export some of the nutrients, phosphorus especially a little bit further from the farm than we are used to with some of our liquid manures.
Kevin Erb:
And there are definitely some exciting technologies I think on the horizon. And I mean, one of the things that I saw in Canada more than a decade ago and I'm beginning to see it more and more across the Midwest is automated systems to change tire pressure. And so when we're in the field, we want a low tire pressure for compaction, for tire wear and tear when we're on the road going to and from the farm, we want that higher pressure for tire wear and tear but also road safety as well. And so these automated systems that change tire pressure, I think, are up and coming. We're going to see more of those. The other thing that you mentioned was the idea of taking manure longer distances and we're seeing companies now that are manufacturing dumpsters and transfer systems where we're going with the semi down the road, transferring at the side of the road and then running a dragline or tanker in the fields.
A real benefit of that is we're not tracking mud onto the road and it's actually a safety thing, but we really need to be thinking about can we work with the town board? Can we work with the county highway department? What can we do to make sure that's done safely? And sometimes it's things like signage, flaggers. Other times we have a number of towns and even counties here in Wisconsin that will close roads for manure applications so that we're able to have that equipment actually not parked on the edge or destroying the edge of the road but parked a foot or two foot off of the edge of the pavement and that makes a real difference. And so that communication with the local elected officials to minimize issues, talk about the things You're doing to minimize tracking mud on the road, to follow the regulations really goes a long way towards preventing problems.
Daniel Andersen:
Absolutely. And I think one more place we've seen at least some companies investing in as we talked about timing and timing can mean lots of things. In the fall we say wait until 50, but it also can mean trying to move more of that manure either to spring or even better in season. And I think that's an area where there's a lot of people saying, "Well, we figured out how to put cover crops on with haggis, with drops." And there's companies that are starting to do that with manure. I know Melissa's done some work on injecting manure into early stage corn. And I have a project where we're using a machine that's got a bar that's 12 feet off the ground. So we're trying to put manure with drops into standing growing corn and I think that's an area where we'll continue to see a lot of investment and hopefully a lot of innovation in new methods to get that manure out there.
Melissa Wilson:
I wanted to mention too, some of the new technologies that we're seeing coming over from Europe are automated in that they're automatically applying manure throughout the growing season. There's these they're basically drop systems where they go out and drop slash irrigation systems where they go out, apply the manure and come back. They're applying really low rates but they're applying it several times throughout the growing season. So that can actually help really conserve your nutrients because they're not sitting in storage for a year then either. So that's been really interesting and like I said, I'm seeing it more over in Europe, but things are starting to make their way over to the US too. So that's something we may see more in the future.
Kevin Erb:
And from a corn production perspective, that's really beneficial because we think about corn from the time I plant that corn until it's just below knee high, it's going to take up somewhere between two to six pounds of nitrogen per acre. Once they hit that growth spurt right about knee high up until they hit those reproductive stages, corn can be taking up one to three to four pounds of nitrogen per day. And what's really interesting is as you look at the newer varieties over the last decade, that nitrogen uptake curve is actually shifting. And so being able to get that manure nitrogen, that fertilizer nitrogen out there at the time of greatest uptake, but also at a time of less environmental risk because we don't have as many intense rainstorms usually during the summer, it really does long-term make a difference both in terms of the yield but also in terms of nitrogen entering the drain tile and heading down the Mississippi.
Melissa Wilson:
Yeah, that's absolutely true. Most of the research has shown that most of the nitrogen, if it's lost from the system, it's lost in the spring before our crops really get growing. So maybe thinking more of this in season application is maybe the way to go.
Kevin Erb:
And I think we really need to be thinking about the technology and how it fits with farm size. When we talk about those fully automated systems, Melissa, and those make sense for the really large farms, but for the smaller operations, if you've got a custom applicator, if they have one of the onboard nutrient sensors that are out there, they can provide that data to use so that you can give that to your agronomist.
But I know a number of smaller farms are kind of looking at some of the GPS mapping technology and pretty much for less than $1,500 you can outfit two different tablets or phones with an app and have your actual setback map on there. And it's not recording where you are, but it's showing where you are in the field in relation to that setback. And what I particularly like about those systems that work on a phone or even a tablet is that these devices have built into them GPS that can put you within 10 to 15 feet of your actual location. So you can be out in the boondocks, not have cellular service and still be able to use that built-in GPS technology.
Melissa Wilson:
Yeah, it's definitely amazing to see what's coming down the line. I think manure was kind of ignored for a long time because people thought of it as just a waste, but as we're starting to see more and more value coming out of it, especially with fluctuating fertilizer prices, people are really getting and companies are really getting innovative with bringing new stuff to the market.
Jack Wilcox:
As we're thinking about manure application this fall, let's think about safety too. Can we talk about that for a little bit?
Daniel Andersen:
Yeah, and I think one thing that Kevin mentioned was mud, hopefully this year given the weather, maybe mud isn't at the top of our mind right now, but mud hopefully is something that we should always be thinking about. But when it comes to operator safety, I think there's a couple of things that really come to mind. The first given where I am in Iowa is always hydrogen sulfide. We have seen a lot more DDGs go in many of our rations. DDGs often high in sulfur and that means we end up with more sulfur in the manure. And that sulfur when we start agitating can come out rather quickly and sometimes result in dangerous conditions for either the animal or the operator. So I really like some of the personal hydrogen sulfide detectors. They beep when you hit certain thresholds like 25 ppm, just a little warning to move a step or two so that you can get fresher air. And I find them really handy for just safety at the site and knowing what's going on.
Beyond that, road safety is always important. Depending on where you are, roads have vastly different use rates. Certainly some of our equipment's really big. Oftentimes in Iowa we deal with soft shoulders on roads, especially in the fall or very narrow shoulders and it's hard to move over very far. So trying to think about routes and what's the best way to get from farm to field, I think, are important. The other thing we've seen a lot more of is people getting rear-ended when they're taking a tanker down the road. And I know there's not a whole lot you can do about that, but making sure you know where those hills or blind spots are, where you might be most prone to getting hit as someone's, maybe glancing down at their cell phone unfortunately, or just not paying as much attention or don't recognize how slow you're moving.
Kevin Erb:
And I think that's really a good point, Dan, because we're entering that time of the year where at sunrise and sunset, if you're going down an east west road, you're going to be driving right into that sun. And I know here in Wisconsin within the last year in a three week period, we had three different fatalities where people crashed into the back of farm equipment because they were blinded by the sun. And so just being aware of that, positioning your equipment, maybe even you may have to pause for 20 minutes while the sun goes down in some cases. If you're doing trans loading on the side of the road or something. But just be aware that that sunrise sunset is actually a very dangerous time, particularly with teenage drivers that are less experienced.
Melissa Wilson:
Absolutely. I think making sure that you have all of the legal road requirements, the slow moving symbols, the correct lights and all of that it's really important too. Or at least making sure before you really get going this fall that all of those are working, so that you're being safe is important.
Kevin Erb:
Yep. Really walking around that equipment not only at the beginning of the day, but also get off your tractor seat, your cab of the truck, get a little exercise, walk around, knock any dust or mud off of those lights, make sure the reflectors are able to be seen, it really does make a difference in terms of visibility if those reflectors, that reflective tape is clean and clear versus 15 years old and faded.
Melissa Wilson:
The other good thing to review this fall, if you haven't already, and I know some people are already getting pretty busy taking silage off the field and whatnot, but thinking about having a safety plan in place or an emergency plan that can be placed in your tractors or wherever it may be so that if there is an incident you can just quickly grab that, you don't even have to think about it, who you need to call. You need to think about what location you're going to be, that sort of thing.
Even if you have teams going, having regular check-ins with them to make sure that everyone's being safe and all of that is really important too. I know Dan talked a little bit about the hydrogen sulfide issues, that's a serious concern and that's one of those ones where if someone has gone into a barn or a place and they pass out, do not follow them because you're likely to pass out too. But knowing that and having a plan in place for what to do in those situations before it happens is really important so that you know what to do when the time comes.
Jack Wilcox:
All right, are there any last words from the group?
Melissa Wilson:
No, I just want to thank Kevin and Dan for joining us, our manure experts from surrounding states. So I appreciate it and I think our big summaries are just follow best management practices. Think about when and where you're going to apply manure and if you can use inhibitors or cover crops or other things to capture those nutrients, you're going to get the best bang for your buck the following year.
Daniel Andersen:
Thanks for the opportunity and happy and safe hauling to everyone.
Jack Wilcox:
All right, that about does it for this episode of the Nutrient Management Podcast. We'd like to thank the Agricultural Fertilizer Research and Education Council or AFREC for supporting the podcast. Thanks for listening.
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