Delivering best practices for using manure on farms

Melissa Wilson is many things: a soil scientist and water quality specialist, a UMN professor, an educator and a mentor. But her real expertise is in manure. 

“I cannot say that growing up, I thought I would be a manure specialist,” Wilson says. “But I’m known as the Manure Prof at the University of Minnesota, and I have the number 1 research program in number 2.”

Valuing manure as a resource matters tremendously to both farmer profitability and the environment, Wilson says. 

“A lot of people just want to get rid of manure. They still consider it a waste,” says Wilson. “But it's a natural fertilizer source. It should be used before we apply fertilizers, because we want to recycle as much as possible,” she says. 

As a manure nutrient management specialist for University of Minnesota Extension, Wilson teaches farmers how to apply manure onto their fields. She consults with manure producers and ag professionals on best practices for storing and transporting manure. She presents research locally, nationally, and internationally, and introduces the concept of manure usage to curious audiences. 

It’s complicated: Unlike manufactured fertilizers, manure is highly nuanced. Differences in livestock animals, their digestive systems and the feed they eat result in differing nutrient levels across types of manure. 

But Wilson, working in collaboration with Extension Engineer Erin Cortus, is taking some of the guesswork out of using manure as a resource on farms. Together, she and Cortus led the creation of ManureDB, a database that collects and aggregates U.S. manure analysis data results to update manure book values over time, allowing farmers across the nation to fine-tune their manure-management planning.

Rising input costs, including the recent worldwide spike in synthetic fertilizer prices, might make manure a more appealing option among corn and soybean farmers who are looking to diversify or hedge against the geopolitical volatility of the fertilizer market.

“Anytime fertilizer prices are high, manure becomes more and more attractive, so to speak,” Wilson says. “Manure has a lot of value that fertilizer doesn't. It has the micronutrients and the organic matter.” 

Intrigued by science

Wilson grew up in a small town in Lancaster County, Pennsylvania, and had a childhood that might sound typical. She loved (and still loves) animals, the outdoors and helping others. 

Unlike most of her colleagues within Extension and the broader agricultural industry, Wilson wasn’t raised on a farm. As it turns out, collecting water samples in a local stream is what nudged her towards a career in agriculture.

During a high school environmental studies assignment, the 17-year-old Wilson collected water samples from a local stream. She then compared them against additional samples taken further downstream. Because some very small insects (macroinvertebrates) survive in water with a certain level of cleanliness, finding the insects more often indicates the water in those sections is cleaner.

“I was hooked,” Wilson remembers. “Finding the insects actually means something about the water they choose. Comparing little parts of my county — that spoke to me.”

Taking the guesswork out of manure

Being as close to certain as possible about the nutrient values of manure is vital for farmers and producers. “Having access to this information — such as ‘this kind of manure in this circumstance gets you this level of nitrogen or phosphorus’ — is important for planning purposes and nutrient management,” says Wilson. 

To take some of the guesswork out of the process, producers all across the country have their samples tested at local and regional laboratories. Those nutrient levels are sent back to the farmers, who can then plan their nutrient management strategy. These data sets helped create benchmarks of what growers could generally expect.

But the contextual or background data that anchored those results might have had unintentional limitations. “If you look at the swine manure numbers, the book values for the entire country were based on 100 samples in Iowa, for example,” said Wilson.

The making of ManureDB

The need for current, more widespread data was evident, so Wilson and her colleagues got started. Funded by a grant from the National Institute of Food and Agriculture (NIFA), Wilson partnered with the Minnesota Supercomputing Institute at the University of Minnesota to begin constructing the database. 

Wilson brought in lab managers from Pennsylvania, Ohio, North Carolina, Georgia, the Nevada / Texas panhandle, and asked what they thought. “And then it just kind of became national from that conversation because there was support for it,” Wilson remembers.

Today, agricultural professionals nationwide use ManureDB to access up-to-date information on over 490,000 samples from 49 states, 14 laboratories, over 65 animal types, and 18 organic amendments. The data can be filtered in a variety of ways — by year, by animal type, by manure storage type, and by state and region. 

Daniel Anderson, a manure management and water quality specialist from Iowa State University, says that manure used to be undervalued because of those prior inconsistencies in the data set. “But as we have more data, people build trust in what's really there,” Anderson says.

With more confidence in manure nutrient values, farmers can do more detailed manure management planning. “We see a lot more people who haven't historically used manure are interested in purchasing it,” Anderson says. “So it really helps you feel confident in what you get back.”