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RULE IMPACT: Using the Minnesota Department of Agriculture’s math, less than 15% of cropland in the state would be affected by the proposed Groundwater Rule, meaning fall nitrogen applications would continue to be an option on more than 85% of all acres.

5 things to know about the proposed groundwater rule

Ag Water Stewardship: The proposed rule only applies to commercial fertilizers, not manure.

The Minnesota Department of Agriculture’s proposed Nitrogen Fertilizer Rule created quite a bit of controversy when it was rolled out in 2017.

Release of the rule prompted much feedback from farmers and others. Over the winter months, the MDA reworked the rule, and in April, it was released in close-to-final form as the Groundwater Protection Rule. Several, but not all, of the concerns raised by farmers were addressed in the MDA revisions. Here are five areas to be aware of:

How can I provide input?
This is an official rule-making effort. The Minnesota Administrative Procedures Act outlines the steps the MDA must go through, including a requirement to hold public hearings. Five public hearings are scheduled July 16-26 at various locations. Administrative Law Judge Jessica Palmer-Denig will preside over these hearings, and receive oral and written testimony on the proposed rule.

Comments can also be submitted through the Office of Administrative Hearings website through July 31. Look for OAH docket number 71-9024-35205.

What will the rule prohibit?
The rule would prohibit applications of commercial nitrogen fertilizer in the fall (after Aug. 31) and on frozen soils in vulnerable groundwater areas and drinking water supply management areas (DWSMAs) with nitrate nitrogen levels at or above 5.4 mg/L. About a dozen counties in northwest Minnesota are excluded from the restriction due to climate factors. There are also exclusions for fall-planted crops and other situations requiring fall applications.

Using the MDA’s math, less than 15% of cropland would be affected, meaning that fall nitrogen applications would continue to be an option on more than 85% of all acres. The MDA reports that 30% to 40% of all N fertilizer applications currently occur in the fall.

You can find the map showing the restricted areas, along with other information, at Additional requirements could follow for DWSMAs that continue to have elevated nitrate levels.

Will the rule apply to all forms of nitrogen?
No, the rule will only apply to commercial fertilizers, of which anhydrous ammonia and urea are the most commonly used in the fall. Phosphorus fertilizers containing nitrogen, like MAP and DAP, can continue to be fall-applied, though rates may be limited. The rule also does not apply to manure, which is already regulated by the Minnesota Pollution Control Agency.

Will regulation be based on private well testing?
No, not directly. One of the major revisions to the rule is the removal of the Township Testing Program (TTP). However, the MDA has said that it will continue to implement the TTP, including private well testing, development and promotion of nitrogen fertilizer best management practices (BMPs), establishing monitoring networks where feasible, and helping to form local advisory teas to involve local farmers and their advisers in water quality issues in their area.

Will the proposed rule result in reduced nitrates in groundwater?
Yes and no, according to the MDA. One of the supporting documents released with the rule is a technical paper called a Statement of Need and Reasonableness (SONAR). In it, the MDA provides examples including that of the city of Perham, Minn., where “through combined efforts of the city and agricultural community over 20 years, average annual nitrate-nitrogen concentrations in community wells have declined.”

The MDA’s Nitrogen Fertilizer Management Plan also provides examples of BMP success in several other communities. However, MDA also provides numerous points suggesting that BMPs are not effective, supported primarily by statewide statistics and concluding that farmers are overapplying nitrogen fertilizers.

I encourage readers to review both the proposed rule and the SONAR and sort this one out for themselves. You can find the complete SONAR and other documents relating to the rule at

Formo is executive director of the Minnesota Agricultural Water Resource Center.


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