Manure tank

A nitrification inhibitor injection tank mounted on a manure applicator. (Image credit: Melissa Wilson, University of Minnesota Extension, Minnesota Crop News)

Whether you farm in Arkansas, California, Iowa, North Dakota, Minnesota, many other states or Canada, the Minnesota Department of Agriculture (MDA) could play a role in your cropping manure application program.

For the past 25 years, the MDA has offered North America’s only Manure Analysis Proficiency Program for laboratories that test manure. The primary goal of the program is to ensure that farmers receive accurate manure test results.

Public and private labs enroll in this program annually. Labs receive unknown samples of manure in May and again in July. The manure is analyzed and results are returned to the MDA to check accuracy.

Then, the participating labs receive graphical and tabular reports for each lab showing how their results compare with the results submitted by the other participating labs.

Labs pay $400 annually to participate in the Manure Analysis Proficiency Program. In addition to proficiency, some labs elect to go one step further and become certified for manure testing through the Manure Testing Lab Certification program. The MDA certifies labs with acceptable accuracy in total nitrogen and total phosphorus, for an additional $100.

Farmers are invited to visit the websites of participating labs at and call the individual labs for more information. By contacting the labs, farmers can learn what tests are conducted and the best method for collecting and shipping samples. Some labs offer sample containers, and it’s important that farmers ship the samples as soon as they are collected.

It’s challenging to accurately test manure.

“The samples come into the lab in different forms and it’s not all the same,” said Larry Gunderson, MDA unit supervisor. “There are different species of animals, different consistencies.”

The program was started in 1996, according to Gunderson. As farmers began to recognize the value of properly-applied manure, a need developed for reliable results. With differences in procedures, lab technicians and equipment, labs needed standardization to get repeatable results.

Gunderson added that the MDA had partners that make the program a success.

Staff at Central Lakes College in Staples, Minn., collect, mix and ship manure samples to the labs.

Dr. Bob Miller, from Colorado State University, received a Ph.D. in Soil Fertility and Chemistry from Montana State University. He’s also the Ag Laboratory Proficiency Program director in Windsor, Colo., and partnered with the MDA to answer important technical questions.

“He runs other lab proficiency programs and he’s really an expert that we’ve turned to with questions,” Gunderson said. “He’s helped us with this program for some time.”

In addition, Dr. Melissa Wilson at the University of Minnesota is leading a team of experts to revise the manure testing manual used by labs.

About 60-70 labs participate in the proficiency program every year, Gunderson added, with five to ten Minnesota, South Dakota and North Dakota programs certified.

In Minnesota, the use of an MTLC program is required by the NRCS for Environmental Quality Incentives Program (EQIP)-funded nutrient management plans, and by the Minnesota Pollution Control Agency as an option for manure management plans and permits.

“Our goal through this is to really ensure the farmers are receiving accurate manure testing results,” Gunderson said. “It is important for farmers to test manure to determine what is in the manure for nutrient values.

“They’re able to adjust the amount of nutrients applied based on the results that came from the certified lab. Testing manure helps farmers to be more precise and make changes if needed in their cropping operations.”

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