Comments on Proposed Nitrogen Fertilizer Restrictions

The Minnesota Department of Agriculture (MDA) has released its draft Nitrogen Fertilizer Rule and is accepting comments through August 11. The purpose of this rule is to minimize potential for nitrate pollution in groundwater and to protect drinking water.

The rule is written in two parts. Part one is a preventative measure that the MDA proposes to apply to all areas of the state that it has defined as “vulnerable” based on geology. In general, these areas would include areas of predominantly coarse textured soils, areas with Karst or fractured bedrock, and areas where there is little topsoil and bedrock is near the soil surface.

Part one of the rule will prohibit application on vulnerable soils from September 1 through spring thaw. It will also prohibit application on all soils in a section where more than 50 percent of the soils are considered vulnerable.

An exemption is provided for a small amount of nitrogen applied with Monoammonium Phosphate (MAP) or Diammonium Phosphate (DAP), or for winter cereal grains. The part one rule does not apply to manure applications.

The areas affected include those in which fall applications of nitrogen fertilizer have not been advised for more than 20 years due to the economic risk associated with nitrogen loss. However, farmers should check the MDA’s soil vulnerability maps to see how closely it aligns with their experience. If you have areas that are identified as vulnerable that you do not believe should be covered by the restriction, you are encouraged to submit comments on vulnerability criteria.

Part two of the rule provides for mitigation in areas where groundwater nitrate levels are elevated due to nitrogen fertilizer use. Identification of these areas takes two paths. The first path covers private wells and uses data from the MDA’s Township Testing Program. If more than 10 percent of wells in a township do not meet drinking water standards, an assessment of the adoption of nitrogen Best Management Practices (BMPs) will be made.

If more than 80 percent of the cropland is being farmed using BMPs, further regulation is unlikely according to the MDA. If BMPs are not being adopted in these areas, part two of the rule will be applied.

It is important to note that wells that have possible non-fertilizer nitrate sources are excluded from this analysis.

The second path applies to public wells and uses data from the Minnesota Department of Health (MDH). If a public well is near or approaching the drinking water standard, the BMP assessment process will be initiated.

Part two or the rule includes level 3 and level 4 and essentially includes those areas nitrate levels are elevated and BMPs have not been adopted on 80 percent of cropland in the area. At that point, the MDA proposes to initiate further requirements which may include rate restrictions, record keeping and reporting of fertilizer applications, crediting of all nitrogen sources (including manure), development of nutrient management and other plans, and required use of nitrogen stabilizers or similar products.

Important- an area cannot move to levels 3 or 4 until at least three crop years have passed, to allow for assessment of BMP adoption.

It is also important to keep in mind that the rule does NOT apply to non-vulnerable soils, with the exception of those sections in which more than 50 percent of the soils are considered vulnerable.

For more information, go to the MDA Nitrogen rule website at