UNL's Schmidt: Manure's Unlikely Friend

Nebraska Professor Devotes Career to Changing Perspectives on Value of Manure

Todd Neeley
By  Todd Neeley , DTN Staff Reporter
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Amy Schmidt, associate professor at the University of Nebraska-Lincoln in the departments of biological systems Engineering and animal science, has spent many hours in the field collecting manure samples from lagoons and just about anywhere it can be found. (Photo courtesy of Amy Schmidt)

LINCOLN, Neb. (DTN) -- In her youth, Amy Schmidt dreamed of making things fly.

She attended Space Camp, built model airplanes and believed she was destined to be an aerospace engineer.

"I was quite a nerd," she said.

Now a professor in the departments of biological systems engineering and animal science at the University of Nebraska-Lincoln, Schmidt is best known in Nebraska agriculture circles as the "manure lady" -- a title she passionately embraces.

"Well, there aren't a lot of people that work with manure as a general area of research and outreach," Schmidt said.

"And when I started, there might have been one or two other females in the country that I knew of that did that type of work. It (the nickname) really kind of came to be when I was here at UNL because farmers would talk to somebody and say, 'well, who's that manure lady that I see on you know, on Pure Nebraska' (public television show)?"


Her family sowed the seeds.

Schmidt fondly remembers many rides aboard tractors and running around in pig barns on her grandpa's farm in southeast Iowa.

Her interest in and outright defense of manure skyrocketed, however, starting with a graduate-level waste-management course she enrolled in at Iowa State University.

During Schmidt's first year at ISU in 1993, jobs in aerospace engineering were few at a time when the national defense budget wasn't as stout.

She knew she had to rethink the future.

Schmidt's high school interests included the environment and in particular at the time when the greenhouse effect was gaining attention worldwide. In high school she competed in science fairs, once completing a project on how crops respond to elevated carbon concentrations.

As a freshman engineering student at ISU, students in ag engineering encouraged her to consider their area of study.

Schmidt visited with ag engineering professor Duane Mangold about the program and decided it was the right path.

It didn't take her long to realize how important waste management is to agriculture.

In graduate school Schmidt worked on a feasibility study as an assistant to a professor, on near-infrared analysis of manure to determine nutrient concentrations during field application.


"So, it was just purely collecting a bunch of samples that we could run to calibrate that equipment and see if we could make it work for predicting nutrients," Schmidt recalled.

Schmidt collected samples from slurry pits and other locations all across Iowa in her first summer of graduate school. She analyzed manure samples on NIR spectroscopy equipment and compared outputs from the system to wet chemical analyses of manure samples.

The goal was to see whether the equipment could be calibrated to accurately predict nutrient content of manure in a new way.

After the project, she went to work as an environmental engineer at Premium Standard Farms in northern Missouri from 1999 to 2001. There she took part in research and developed odor-control practices and nutrient-recovery methods. She oversaw construction of manure storage and compliance with regulatory reporting requirements.

A position opened up at the University of Missouri in extension that didn't require an advanced degree, which Schmidt said was rare for a faculty position.

It was there she developed a love of extension work and helping farmers solve problems.

She and her husband Ty moved to Mississippi in 2007 where he worked as an assistant professor at Mississippi State University while Amy earned her Ph. D.

In 2012, they went to work at UNL and have been there ever since.


Schmidt said during the past several years a lot of her research has focused on soil health and how manure affects soil properties that reduce erosion, runoff and nitrate leaching.

Today, she said she finds herself having more conversations with farmers about cropland resilience.

"In agricultural systems, manure kinda gets a bad rap as being, inorganic fertilizers OK for the environment, but manure is bad for the environment," Amy said.

In addition, Schmidt said she supports livestock and poultry producers who look for options to manage mortalities on their farms.

In 2020, supply chain backups forced many farmers to cull livestock because processors faced reduced capacity. Schmidt worked with producers on how to dispose of animals, milk and other ag products and currently has a graduate student working on the project.

"So, they want to be able to tell farmers if it happens, here's the best system to use on your farm and disposal is to prevent environmental contamination but also disease transmission," she said, where one of her students is helping to find solutions.

Two undergraduate students came to Schmidt's laboratory a couple of years ago with an idea to study whether it's possible to harvest nutrients from duckweed growing in feedlot runoff holding ponds.

Students have led projects to identify carbon and nitrogen dynamics in soil with manure or wood chips applied and developed a machine-learning algorithm to analyze images for evaluating soil biological activity.

Exploring antimicrobial-resistant bacteria and genes that could enter the environment through animal manure continues to be important as well.

"We consider what methods of planned application should we use so that we know we're not having run off of pollutants that are resistant to antibiotics," Schmidt said.

"My hope is that I eventually circle it back to if we have healthy soils and we have resilient landscapes where we don't have erosion and runoff, then we're also seeing a reduction in this potential for resistant bacteria and genes to be transmitted beyond the farm."


Schmidt said she's intrigued by hesitancy among farmers to fully embrace manure in cropping systems.

"We do a lot in trying to understand the reasons crop farmers don't want to use manure and then trying to mitigate those barriers so that it becomes more common for them to use manure in their systems," she said.

"So, when used correctly, manure is going to improve environmental quality overall. We're trying to kind of change that dynamic to where they think about, 'oh, if I build my soil up, and it's healthier, I can use fewer inputs, nutrients and pesticides and get the same results.'"

Some farmers have been softening on the notion that they have to get rid of manure rather than reap its benefits, Schmidt said. Farmers are figuring out ways of taking advantage of the nutrients.

In recent times of high fertilizer prices, farmers have started to consider manure as an alternative to inorganic fertilizer.

In Nebraska, Schmidt said she sees private consultants work more with large animal-feeding operations to help broker manure as a product. "So, like you have this many tons of beef manure with this nutrient content, and they go out and they find crop farmers who say 'yeah, I would buy x amount of that for my field.'"

In 2022, Schmidt said a consultant told her it was the first time they'd had all the manure they handled committed to buyers for the following crop season.

"We're seeing manure bought and sold as a commodity," she said. "Obviously, the market is really developing to where we can move those nutrients from a place where they're highly concentrated out to other locations."


Some farmers question whether analyses done on manure are accurate when it comes to nitrogen content. Others are concerned manure could contain herbicide-resistant palmer amaranth seeds, or they lack the equipment to land apply manure, Schmidt noted.

Many producers are concerned applying manure on land could cause soil compaction.

"We've got research that shows manure actually improves soil bulk density, which is kind of the counter of being more compact," Schmidt said.

Although environmental groups often claim animal-feeding operations of all sizes should be regulated to control nutrients runoff and manure mismanagement, Schmidt said she believes most farmers want to do the right thing.

"I feel like people think smaller farmers are going to manage manure better because they don't have as much and don't have as many animals," she said. "And I think, for the most part, our smaller farmers do just fine because they probably own enough land to manage that manure.

"But what people may not realize is that the larger farms, the CAFOs, concentrated animal feeding operations, they have a lot of regulatory oversight that our smaller farmers don't, based on their size. So, they have a lot more restrictions on when, where and how they apply manure to cropland."


A lot of what Schmidt and her extension team do is work with smaller livestock farmers and crop farmers to better understand manure's value and to avoid applying more than a crop needs.

Producers often need to better understand the different manure application methods and how the methods affect the environment, and how manure can make cropping systems more resilient.

One of Schmidt's studies recently found greater variability in nutrient application rates from cropland-applied beef manure, when travel speed of a spreader is not well-controlled, than with variability in nutrient concentration by load.

Simply writing down spreader settings and the tractor gear used while spreading is an easy way to maintain consistent nutrients application, she said.


How farmers make decisions about manure continues to be an area of research for Schmidt. She worked with extension partners in Iowa and Minnesota to conduct a national survey to better understand attitudes.

"And one of the most interesting parts of that data to me was overwhelmingly crop farmers, livestock farmers, advisors, all said 'we totally recognize that manure is good for biological health of soil,'" she said.

"We know it's good for agronomic productivity. We know it improves soil physical properties. But we don't necessarily think it's good for the environment. And so, my takeaway is that we have not done a good job of showing how much soil quality impacts water quality."

The process of learning and teaching never ends.

"I always joke with people, like in extension your first goal is to change a person's knowledge of something, then it's to change their perception," Schmidt said.

"And eventually you hope that you convince them to implement that practice and see results from it. I sometimes joke, like, I'm probably going to work my whole career just getting people to recognize and appreciate the value of manure."

Todd Neeley can be reached at todd.neeley@dtn.com

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Todd Neeley

Todd Neeley
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