Groundwater Protection Rule restricts fall nitrogen fertilizer use in Vermillion River Watershed

A reminder that starting September 1, 2022, the application of nitrogen fertilizer in the fall and on frozen soil is restricted in areas vulnerable to groundwater contamination under the Minnesota Department of Agriculture Groundwater Protection Rule.

The Fall Nitrogen Fertilizer Application Restrictions map is viewable on the MDA website. Farmers are encouraged to check the new map to determine if their fields are subject to these restrictions. The majority of the land in the Vermillion River Watershed is vulnerable to groundwater contamination and most farmers and commercial applicators must restrict nitrogen fertilizer use.

Areas with coarse-textured soils or areas above fractured bedrock or karst geology are the most vulnerable to nitrate loss and groundwater contamination. Nitrate contamination can be a significant localized issue due to sandy-textured soils, shallow distance to groundwater, and heavy irrigation use. Crop failure and water stress under dry conditions can also leach nitrogen into the ground.

An updated map of public water supply wells with elevated nitrate levels can be found here on the MDA’s website.