Nitrogen fertilizer restrictions in Minnesota begin September 1

The Minnesota Department of Agriculture (MDA) is reminding farmers and landowners that beginning September 1, 2020, the application of nitrogen fertilizer in the fall and on frozen soil will be restricted in areas vulnerable to groundwater contamination.

This will also apply to Drinking Water Supply Management Areas (DWSMA) with elevated nitrate levels. Vulnerable groundwater areas include coarse-textured soils, karst geology, and shallow bedrock.

Approximately 12% to 13% of Minnesota's cropland is vulnerable to groundwater contamination. A map showing the vulnerable groundwater areas as well as a list of exceptions to the restrictions are outlined on the Groundwater Protection Rule website.

Part One

Part 1 of the Groundwater Protection rule restricts the application of nitrogen fertilizer in the fall and on frozen soils if you farm in 1) an area with vulnerable groundwater or 2) those protection areas around a public well, known as a DWSMA, with high nitrate.

An entire quarter-section is included if 50% or more of a quarter-section is considered vulnerable.

Part Two

Part 2 of the rule responds to DWSMAs which already have elevated nitrate. The goal is to take action to reduce nitrate in groundwater before a public well exceeds the health standard for nitrate. The rule is structured using a sliding scale of voluntary and regulatory actions based on the concentration of nitrate in the well and the use of the BMPs.

The MDA will form a local advisory team with farmers, agronomists, and other community members. This team will be involved in reviewing, considering, and advising the MDA on appropriate practices or requirements to reduce nitrate in the DWSMA.

There are four mitigation levels used to determine voluntary and regulatory actions, two voluntary levels, and two regulatory levels. All areas will begin at a voluntary level and move to regulation only if BMPs are not adopted or if nitrate contamination in the groundwater increases.

The MDA will hold a webinar on August 12, 2020, from 10:00 to 11:00 a.m. to answer questions. The video and webinar details are available online.

The nitrogen fertilizer restrictions are part of the Groundwater Protection Rule, which minimizes potential fertilizer sources of nitrate pollution to the state's groundwater and works with local farmers to prevent public water supply wells from exceeding the drinking water standard for nitrate contamination.