Circularity and Systems Thinking in Manure Management

Our first podcast examines the science, technology, and best management practices surrounding manure management. Dan Andersen, Rachel Kennedy, and Melissa McEnany discuss circularity and systems thinking in livestock and manure management.  Find show materials here.

Transcript

Dan Andersen  00:06

Hello and welcome to our inaugural episode of Talkin' Crap, a podcast by Iowa State Extension and Outreach, where we discuss insights into the science, technology, and best practices surrounding manure management. Our objectives are to build awareness about the challenges farmers and the broader agricultural industry face around manure and demonstrate solutions in areas of innovation. This week, we'll be helping you get to know us and talk about circularity and systems thinking as applied to livestock manure management. So buckle up, and let's get to talkin' crap. I'm Dan Anderson, Associate Professor and extension specialist in the Agricultural Engineering Department at Iowa State University. You may know me better by my Twitter handle, Dr. Manure and if you don't check me out there. Joining me this month or two of my close close colleagues here at Iowa State University, the Poop Princess Rachel Kennedy and the Duchess of Dung, Melissa McEnany.

Rachel Kennedy  00:59

Hi, I'm Rachel Kennedy. I am the princess. I'm the program coordinator for the manure applicator certification program, and the CEO and Managing Editor of the Poop-a-Palooza paparazzi, I also have duty other duties as assigned. It's a great being part of the team. 

Melissa McEnany  01:18

Hi, I'm Melissa McEnany. And I'm also known as the Duchess of Dung. I'm an Extension Program Specialist and I fancy myself a jack of all trades and master of none. My primary focus is the online manure applicator certification program. And I also work with some youth outreach activities.

Dan Andersen  01:37

Great. As always, we're thankful to have you all join us. And I'm especially thankful to have my team here and supporting us as we make it through this first episode. So as I decided to start this podcast, I tried to think about what I wanted it to be. What is there to say about manure? Turns out a lot. I love to talk crap. While manure may seem an unconventional topic for a podcast, it plays a significant role in farming, soil health, and even energy production. Given these challenges, discussing this ancient fertilizer in precision ag seemed more crucial than ever. So as I looked at what we were trying to accomplish, I really had three different thoughts rolling around in my head about where we'd go with this podcast. The first was agriculture and sustainability. Manure is crucial in agriculture and sustainable farming practices. It's a natural fertilizer that provides essential nutrients for crops, improve soil health, and reduces the need for synthetic fertilizers. So one of our primary objectives will be discussing the importance of manure and sustainable agriculture. We'll explore different methods and techniques of handling and managing manure and highlight practices that impact crop yields, water quality, and sustainability.  Our second focus is really environmental impact and that's an area we get to talk a fair amount about. Manure management has significant implications for the environment. Poorly managed manure can lead to water quality challenges, air pollutions, and critical issues like algal blooms in the Gulf of Mexico, contamination of water sources and fish kills here in Iowa, and even greenhouse gas emissions that lead to greater climate variability. Discussing these environmental impacts sharing strategies to for responsible manure handling will help raise awareness among farmers, practitioners and technical service providers to promote better practices. As importantly, it's a chance for those in the public to hear and engage in a conversation about what is happening on the farm, and learn where technology is taking us and why.  And finally, our third point circular economy and manure management. Circular economy has become a really big buzzword and it's an area where I think manure takes center stage. Manure can be a valuable resource or a waste product. Livestock manure can be used for various purposes, fertilizing crops, generating biogas through anaerobic type digestion, producing compost, or even developing and serving as fertilizers and other innovative ways. Given the pervasive use of the term circular economy and all its application for the bio processing and bio product and industry, it seems like a great time to help share some of the lessons we've learned from livestock and manure to help these industries be better. Alright, with that, let's get going. Manure fact.

Melissa McEnany  04:21

In Iowa livestock manures can provide 25 to 30% of the nitrogen, phosphorus, and potassium we need to support agricultural production.

Dan Andersen  04:30

That's right. While Iowa leads the nation in pork and egg production with strong dairy, beef and turkey industries, our large crop production, primarily corn and soybeans requires large amounts of fertilizer to sustain production. While it can be easy for many to think of manure as a waste, after all, that's how human waste is managed. It can be a resource for many years, farmers in Iowa and the Midwest have focused on becoming more circular and using their manure nutrients to support crop production. While the 25 did 30% number is valid for statewide, generally, the low nutrient density, at least compared to commercial fertilizers limits how far we can move manure away from the livestock farm. So while statewide information provides a broad perspective, if manure will be viewed as a waste or resource, we have to find a place to dispose or use of those nutrients that we can take advantage of to provide a low cost fertilizer, and that often happens at a more local level. When you look more closely at different Iowa counties, 15 of our counties get less than 10% of their nutrients for crop production from livestock manures, so extremely manure poor. In contrast, only a couple of counties, about three, get more than 70% of their nitrogen from livestock manure. So I will a great state for life sack production, but also a great state for utilizing that manure to support our crop production.

Rachel Kennedy  05:58

If you're interested in learning more and seeing how specific counties are doing, take a look at Iowa State University Extension and Outreach publication AE 3608, Too much manure, can Iowa use all of its manure for fertilizer? While it's not a perfect answer, it does give us a good starting point.

Dan Andersen  06:21

Yeah, and that publication is based on census of ag data. And I know I for one, I'm really excited to see the 2022 Census of Ag data come out with new livestock numbers and crop production numbers to see how different counties have changed. So with that, I think we're ready to move into today's main topic, circularity and systems thinking in livestock manure management.

Melissa McEnany  06:44

Yeah, circularity refers to closing the loop in resource flows where waste from one process becomes a valuable input for another process. In livestock manure management circularity involves treating manure as a valuable resource rather than a waste product. instead of considering the newer solely as a disposal problem, circularity emphasizes its potential to be transformed into valuable products and services. I know this sounds a bit silly to many of the livestock farmers in the Midwest, because of course, that's what we're trying to do, but Dr. Manure will go through a couple of examples.

Dan Andersen  07:21

So in terms of nutrient recycling, livestock manure is rich in nutrients such as nitrogen and phosphorus. Instead of allowing these nutrients to pollute water bodies through runoff or leaching. The concept of circularity involves capturing and recycling them. Nutrient recovery technologies can extract valuable nutrients from manure, which can then be used as crop fertilizers, or even feed additives in livestock diets. Using manure reduces reliance on synthetic fertilizers and minimizes nutrient loss from our agricultural systems. A great example of this that we've seen occurring in livestock in Iowa is moving some of our beef finishing cattle under roof instead of open lots where the manure is subjected to rain and other weather events where it's more prone to movement and eventually nutrient loss. It's stored in a covered area that helps keep it more concentrated and available to be used as a fertilizer product.  A second area that we're starting to see some interest in is energy generation. Livestock manure can be used as a feedstock for anaerobic digestion, producing biogas, which is mainly methane, and also a digestate. Biogas can be used for electricity and heat generation or even as a transportation fuel, reducing our reliance on fossil fuels. The digestate, a byproduct the anaerobic digestion process, helps improve nitrogen availability in the manure, and in doing so it makes it a better fertilizer product. The economics behind anaerobic digestion systems can sometimes be challenging. As a result, we haven't seen as many implementations in this area as where they can just cover a lagoon and capture the generated biogas. However, we are starting to see more of these systems come to Iowa. And finally, use of manure as bedding and for compost. The bedding materials used in livestock housing, such as straw wood shavings can be integrated into a circular system. After being soiled with manure, the bedding can be composted, and returned to the land as an organic matter where it adds to the soil carbon pool, replenishes soil fertility helps improve soil structure, and probably replaces some synthetic fertilizers. It can also help control pathogens and reduce odors associated with livestock manure. In other cases, especially with dairies, we started to see some dairies utilizing solids separation from the manure and then recovering that solid material and using it as a bedding product for their cows, which can work really well if managed correctly. So all these things are ways that we can work with circularity and prove our circularity or have already made great strides and becoming a more circular industry.

Rachel Kennedy  10:01

Then you throw in the systems thinking, aspect. Systems thinking involves considering the interactions and interdependencies among various systems components, including livestock production, manure handling, nutrient management, and environmental impacts. By adopting a systems thinking approach, we can better understand the complex relationships within the system and identify potential leverage points for intervention.

Dan Andersen  10:31

That's right. And it may not seem like the most practical definition at first, but it really can help provide some insight into the challenges we face in our manure management. System thinking can help in for example, integrated manure management. Livestock manure management systems should be viewed holistically considering the entire lifecycle from manure production to end use. So systems thinking encourages integrating that manure management practices with other agricultural activities, most of the time crop production, since it offers the opportunity to optimize resource utilization, and minimize negative impacts by finding a valuable use for the manure. I think that's one of the huge advantages we've really had in the Midwest, we grow a lot of crops, we need fertilizer, and manure can play a big part in that. So when we talk about circularity systems thinking, it comes a little more natural to many of us here in the Midwest.  What this systems thinking means to me is that we need to care and worry about separating crop and livestock systems, both spatially and operationally. A fundamental tenet of nutrient management, and as a result, manure management, is that a strong link between livestock production and crop production is required to encourage nutrient circularity and view manure as a resource, because it gives us a place to use it, value it, and take advantage of what it offers. Sometimes, this conversation gets framed as non intensive agriculture, extensive agriculture versus an intensive agricultural approach. And I don't think that framing is always fair. Extensive agriculture relied on system where lots of land was available, and where nearly all the items generated on that land, food, fiber, shelter, fuel stayed on the farm. When you in that system, there's an inherent circularity because everything stays close to home, making recycling nutrients more straightforward and natural and necessary b ecause we don't have other inputs. The lack of availability of fertilizer options, for instance, made manure a crucial resource for the farm, it was the only way they could replenish and rebuild their soils. So livestock provided a way to collect nutrients, often by grazing, concentrate them in the manure, and then use him as a fertilizer on our higher value crops.  The invention of the haber bosch process, which is really our nitrogen fertilizer generation process allowed us to do something different. For the first time in human history, we had nitrogen available to be an input to our cropping systems that didn't come from livestock. We weren't entirely reliant on manure and could move to a system where higher productivity allowed fewer farms, fewer farmers, but also a system where those agricultural products were shipped from the farm to a city at much greater rates. And in doing so many of those nutrients were removed from wherever they were harvested to a place quite far away. But the availability of those nutrient fertilizers allowed a simple way to replace what we had taken out and sold. And this concept has led to the idea of sustainable intensification. sustainable intensification in livestock refers to a set of practices and approaches aimed at increasing agricultural productivity and efficiency, while minimizing negative environmental impacts. The idea is to still be productive to help feed the world and ensure long term viability of the livestock industry. It involves adopting strategies that optimize resource use, reduce waste, enhance animal welfare, and encourage profitability and production. It's a merging of many of the concepts of intensive and extensive approaches that we've had, and trying to push forward to make it even more circular. I think it's critical for us in the ag industry to help take those first steps to ensure that we can keep farming, keep being productive, and help reduce some of those environmental impacts that we've had.  Another aspect of systems thinking is feedback loops. Systems thinking helps identify feedback loops that are present, for example, nutrient imbalances in manure application. Too much phosphorus relative to nitrogen can lead to water pollution, right, we end up putting more phosphorus than we need on it has a greater chance for movement. Understanding these feedback loops allows for implementation of strategies that break the negative cycles and promote positive outcomes. One of my personal favorite examples of this is how our manure land application decisions impact our ability to manage manure storage, and how sometimes a full manure storage forces our hand up land application, and maybe makes us apply at a time when otherwise, we don't want to.  And I think that takes us to the last thing we wanted to cover today. How do we think about manure management as a system? What does the system need to accomplish? What stages of manure management are there? And how do the different stages work together. So when I think about a manure system, there are really five parts or stages that need to happen. So to help deal with this part of the discussion, we do have a poster picture available and encourage you to look at it. The five stages really are: stage one, housing of animals and containing the manure, stage two, manure collection and water recycle if needed, stage three, storing the manure and treating it, stage four, getting it from wherever we have it stored to where we're going to use it in stage five, manure application or utilization. So we'll go through each of those stages in just a little bit more detail.  So stage one housing animals and containing manure. I know it seems like a really simple one. But when you look at the alchemy, you're trying to turn manure into gold of manure management. A valuable resource that we want containing the manure is extremely important. If we don't have it, it's really hard to take advantage of. The other thing that's a big part of that is ensuring that clean water is diverted around the facility to avoid contact with the manure and nutrients. Trying to keep that manure as concentrated as possible, lets us handle less of it gives us less to store so smaller sports storage, and allows us to apply less per acre, all things that help improve the economics of moving and land applying manure. But it can be more than that. This stage is about how manure interacts with animals. How do our systems work at keeping animals disease free and biosecure, what air quality challenges might be present because of the choices we make? And even how does the feeding program or the ingredient choices impact our manure quality. We've seen a lot of work and continues to see a lot of work in those areas. We're not going to dive in deeper today. But that'll probably be some topics that we can hit on again in the future.  Stage two is manure collection and water recycling. There are many different methods of manure collection, gravity scraping flushing belts. But this is the part where we intervene and actually have to do something right, it's contained, it's sitting there, we need to get it to our whatever's next and that means we have to do something. Just like when we flush a toilet in our house, this is our chance to influence the animal production area for air quality. And what happens next in our manure management system. Many of the options are well established, for example, using gravity at a deep pit barn. After all, Isaac Newton shows up for work every day. But this is still a place of innovation. Some current examples that are just starting to be put into practice are still being developed are things like belts at many of our poultry houses, instead of a high rise facility to help with manure drying and getting the manure the poultry litter out of the barn, or even scraper systems that try and perform solid urine segregation, right at the point of excretion. Right? So you might think gravity has done this for years, we're good. It's still an area where people are finding new ways to innovate.  Stage three is storage and treatment. Many, many storage options exist lagoons, pits, tanks, holding ponds. If you're working with solid, solid manure, maybe stacking sheds and stockpiles, each is a little different, but the fundamental distinction is whether we are dealing with solid, liquid, or slurry manure, right? If we have solid manure, you get one set of options. If you're a liquid, you need something else because it's harder to contain a liquid. It's also an exciting place for me, because it's where system thinking really comes into the play the type of storage picked and its size set a tone for what are we going to need to do for land application? How long can we wait? What cropping systems can we work with? Throwing the term treatment into this component can make things a little bit more complicated. And while we often don't have much need for treatment on many of our Iowa farms, because we want to store it, keep it concentrated and then give it to the field times can change and certain farms might see an advantage in trying to add some more treatment or activity that might make their manure more useful. For example, adding a solid separation or sand recovery system for bedding recovery on a dairy or looking for anaerobic digestion because we want to make energy or natural gas for transportations fuel. It could be also treatments that help reduce some of the nutrient loss, especially nitrogen while it's being stored in the manure to make it a more valuable fertilizer product.  Stage four is manure transport. And that's really where the rubber meets the road. Quite figure literally right. That's the part where we have to move it around. It's all about getting it from our storage to where we need to use or dispose of the manure. Most often this is loading it into tankers trucking hauling it or using it and umbilical system to pump manure. This is one of the most exciting areas because when manure is out and about accidents, leaks, spills, all can happen. It's a big driver of when manure isn't a resource, or when it's a waste. If we can get it to whatever place we need it cost effectively looks like a resource to us. If it costs us more to get into that field, then what other fertilizer options would we start thinking, Man, this is a waste. How do I how do I deal with this stuff? I think technology has done a lot to help push us to cost and time effective practices, which means opportunities to understand, develop, and innovate. And I think one of the things when I look at the manure industry and agriculture, it's always amazing how many companies companies that are out there helping push the limits, trying to find ways to help get manure from A to B easier, more cost effectively, and make sure that we really can value it as that fertilizer resource.  And finally, stage five is manure utilization. This almost always means land application. But it could be other things, for example, selling manures compost or potentially either burning it as a fuel source. While some of those cases are more rare, they have and do occasionally happen. In general, this is where we see a lot of overlap with that agronomic system that we're using. So one of the key reasons we talk about how to integrate crop and livestock systems, so that manure can be a resource is because this stage five helps influence every other stage along the way.

Melissa McEnany  21:36

It's worth noting that the stages and processes involved in the newer management can vary depending on the type and scale of the operation, local regulations, environmental considerations, and available technologies. For example, most swine facilities in Iowa use deep pit barns for manure collection and storage. Historically, the swine industry in North Carolina has tended towards shallow pit or gutter barns and lagoons for storage. The regional differences speak to how weather and cropping systems can affect our manure choices.

Dan Andersen  22:12

Well, that seemed like a lot for the first episode, but hopefully it gives you a taste for our perspective and the approach we'll be taking for our Talkin' Crap podcast. Speaking of taste, I have a manure joke for you. A farmer friend told me that manure is excellent for strawberries. I said you may be right, but I still prefer whipped cream. With that, thank you for joining us for our first podcast. 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, Iowa Manure Management Action Group which you can find at www.extension.iastate.edu/immag. If you found what you heard useful today, or it made you think we hope you'll subscribe to the show on your podcast app of choice. We hope you'll tune in next time as we take a look at the carbon footprints of swine production and what it will mean for manure management moving forward with that, signing off from a job that sometimes smells but never stinks. Keep talkin' crap.