Laboratory Certificaton By the Minnesota Department of Agriculture for Soil Testing and Manure Testing.

The Minnesota Department of Agriculture certifies laboratories for both soil testing and manure testing. Soil testing certification is based on a laboratory’s performance in either the North American Proficiency Testing (NAPT) or the Agricultural Laboratory Proficiency (ALP) soil proficiency programs. The department certifies laboratories for manure testing based on their performance in the department’s Manure Analysis Proficiency (MAP) Program.

For soil testing certification, laboratories must score at least 80 percent for three of the five following tests:

1. Inorganic nitrogen.
2. Phosphorus by Bray, Olsen, or Mehlich.
3. Potassium by Ammonium Acetate or by Mehlich.
4. A buffer pH (SMP, Sikora, Adams, or Woodruff).
5. Soil Organic Matter (Loss on Ignition or Walkley-Black).

Approximately 80 percent of laboratories participating in the MAP Program meet our requirements as a certified manure testing laboratory. For manure testing certification, laboratories must have acceptable results for both total phosphorus and for total nitrogen using either nitrogen by combustion or total Kjeldahl nitrogen.

We evaluate tests other than the required tests for soil or manure individually. For each certified laboratory, our web sites list the tests with acceptable results and users should look at our web site to ensure the laboratory they select is certified to run the desired tests.

Certification is voluntary; however, several states require some livestock producers to use a certified manure testing laboratory. In addition, the use of a certified manure testing laboratory is part of the national Natural Resources Conservation Service (NRCS) 590 standard for nutrient management planning. The NRCS state offices in most states follow the national 590 standard and require the use of a certified manure testing laboratory for farmers to receive reimbursements for nutrient management planning.