Features Applications Research
The more you know

Which nutrients can be found in manure these days, and in what proportions? And how can this information be used to aid farmers in applying the right kinds and amounts of manure as fertilizer?

Answers to these and other manure-related questions can be found online at

ManureDB (http://manuredb.umn.edu). Short for ‘Manure Database’, ManureDB collects nutrient data garnered from standardized manure laboratory analyses and then creates updated ‘book values’.

The website then organizes this data by year, manure source, and nutrient composition by percentage (total solids, nitrogen, phosphorus, potassium, sulfur, and ammonium-N), so that users can make informed fertilizer decisions.

Melissa Wilson is one of the driving forces behind ManureDB. She is an associate professor at the University of Minnesota who works in extension and research, with a focus on manure management.

Nancy Bohl Bormann is a PhD candidate at the University of Minnesota whose main project during graduate school was working on ManureDB.

Manure Manager magazine spoke with them both about the genesis, structure, and usefulness of ManureDB. Here is what they told us.

Manure Manager: What is the story behind ManureDB?

Melissa Wilson: When I first got to Minnesota, one of the things that I really started thinking about is how we don’t really have good book values of what manure nutrients look like that are recent. All of the book values that we have are from the early 1990s-2000s, and things have significantly changed since then — whether it’s diets, we’re raising bigger animals, all of those sorts of things. And all of those will influence the nutrients that are in manure. 

Nancy Bohl Bormann: My thesis advisors Dr. Melissa Wilson and Dr. Erin Cortus at the University of Minnesota proposed this project and received grant funding for a U.S. manure test database in 2020. As manure management experts they get questions about what are expected nutrient values for different manure types, and they have noticed some differences in current manure samples and published book values. Many of the published book values or approximate nutrient concentrations were gathered over twenty years ago, usually from just a few states.

Animal feeding, housing, genetics, manure storage and handling, and nutrition continue to evolve, influencing the nutrient concentrations in manure. So ManureDB was created to aggregate manure analyses from across the country into a dynamic database in partnership with the Minnesota Supercomputing Institute. The accompanying ManureDB website was publicly launched in summer of 2023, with the data download feature released in January 2024. 

MM: What values are covered in the ManureDB charts, and why?

Wilson:A lot of times when people call me and ask for typical nutrient content of manure, they’re often looking for nitrogen, phosphorus, potassium, and sometimes other nutrients. I get questions about sulfur. Sometimes we get questions about how much carbon might be in manure, some of the micronutrients, some of the secondary nutrients like calcium and magnesium as well. So we included all of that information in the database. 

There’s also characteristics, like solids content, and some of the other information that we included would be animal species. If we know where the samples came from, what kind of storage system they came from, that information might be included. So it’s basically anything that would be included when a submitter takes a manure sample and sends it to a lab, whatever information they include for that manure sample will potentially come to us. The only thing we don’t get is any personally identifying information. So at most we will know the state that the manure came from, maybe the first three digits of the zip code, if that’s shared with us, but not the full zip code. We don’t have addresses, we don’t have customer names or anything like that.

Bohl Bormann: Currently on the homepage you can review some summary statistics for beef, dairy, swine, poultry, sheep, and horse for the analytes of total solids, total nitrogen (N), phosphorus as P2O5, potassium as K2O, sulfur, and ammonium-N. All of these are shown with units as percent and on a wet (as-received) basis. We encourage use of the median values, as outliers have less influence on them compared to means (averages). 

MM: How is the data compiled?

Bohl Bormann:First, a data use agreement is signed between the laboratory/data partner and the University of Minnesota as data privacy is an utmost concern. The data arrives in spreadsheets from the laboratories, and we ensure it fits our standardized data template. It then passes through two validation steps prior to uploading to the database where the data is stored in common units for all analytes.

MM: How is the data being used, and who is using it?

Wilson: There is actually a wide range of the manure user community, people that would use this information. And we see it kind of helping farmers who might be planning new manure storages because they want to know how much nutrients they might have in that storage in a given year. So that helps them plan. 

We have agricultural consultants who might be writing manure management plans, and if they don’t have a good idea of what the nutrient content is of the manure that they’re planning for, they can look up these book values. And it’s also really good for farmers and ag consultants to compare their manure samples to regional values, to see if there is something off. Are they running in the normal ranges? Is there something they need to tweak? 

So, we see the agricultural community using it that way, but we’ve actually had a lot of interest as well for researchers who are doing modeling or other exercises, looking at nutrient content of manure, they can actually get real numbers instead of using these old numbers from the 2000s. And that helps improve the models or whatever they’re trying to do for their research.

Bohl Bormann: Since manure is so variable in nutrient concentrations, having an actual manure test for your farm is always the best for calculating application rates. However, when creating nutrient management plans for new farms with no manure history, comparing regional nutrient values for an animal type, wanting to benchmark your farm’s manure, or use in agricultural research, this could be a helpful resource.  

MM: What overall value does this data provide to your users?

Bohl Bormann: This is the largest project of its kind that we are aware of, and it is planned to continue collecting manure sample data on an annual basis to keep the database growing and current. Caution must be used with the data however, as not all samples have great detailed metadata, such as manure storage type or animal life stage. Some parts of the country have greater lab participation, and therefore have more samples to influence the database. We plan to archive the data annually in USDA’s Ag Data Commons.

MM: Beyond helping with application rates, what else is this information useful for? Could it inform decisions such as storage, or even decisions made at an animal level; such as diet?

Bohl Bormann:The project accepts whatever analyses a laboratory runs on samples, so besides macronutrients, we record micronutrients and metals, along with other ratios and measurements. A researcher was interested in the carbon content of manure, and while that is not a routine measurement, we did have some samples with carbon measured. Other less often measured analytes such as chloride are available for review. A laboratory had some detailed information on poultry litter treatments and bedding types that could be of interest for comparisons. Having increased metadata included with sample results will add more utility for other uses.

MM: What response have you been getting to ManureDB, and what impact is it having in the industry? 

Bohl Bormann: We have received interest and excitement for the project from parties working in all sorts of aspects of manure management and our website analytics show people from 20 different countries have visited the website. Again, this is a very new resource that is continuing to evolve, and we are still working to add collaborators and more data while improving the website.  

Wilson: We’ve actually had a lot of positive responses even from areas of the industry that we hadn’t even considered. For instance, the American Biogas Council is really interested in knowing what kind of gas production they could get out of manure. So they’ve been really interested in trying to help us find data to put into the database so that they can use it for modelling those sorts of things. So it was kind of an interesting factor that we hadn’t really even considered. 

But even with our farmers, I can pull data from the database that’s recent and relevant from Minnesota, the upper Midwest — wherever it may be — and show them what the trends are looking like over time, and what the trends are currently. They’ve been really interested to see this data because they might know their barn or the barns that they work with, but they’ve been really intrigued to see how that compares to what we see kind of in the regional averages. So overall, it’s been pretty positive.

MM: What are your future plans for ManureDB? 

Wilson: Our plans are to get continued funding so that we can have updates annually. Right now, all the data that we’ve pulled from different labs around the country, they’ve given us data as far back as they can. So we have some data back into the 2000s up through current. Sometimes labs are more recent where they can only give us five years, 10 years, and so forth. So just kind of filling out the database more, getting more lab partners from different areas of the country will definitely be helpful. Right now, we have manure samples from almost every state except for Alaska. Having that regionality will be really important moving forward, because right now all the book values that we have in the country are national and they typically are not necessarily representative of all the different regions. •