Minnesota adds thousands of acres to areas where nitrogen fertilizer use is restricted

ST. PAUL — A change in the way Minnesota creates the maps for its groundwater protection rule has added 850,000 acres of land to areas where fall fertilizer applications are restricted.

The Minnesota Department of Agriculture updates the maps for the groundwater protection areas each January.

The maps are created by layering different maps of vulnerable areas where fertilizer use is restricted because of course-textured soil, or what's below the soil: shallow bedrock or karst geology .

"There had been inaccuracies in the way the layers were superimposed," said Dan Stoddard, assistant director of the Pesticide and Fertilizer Management Division with the Ag Department.

This year, the maps were generated by the Minnesota Geospatial Information Office , known as MnGeo.

The result was more than 850,000 acres in Minnesota where fall fertilizer applications will be restricted as of Sept. 1.

Here is how the numbers break down:

• Restricted acres in 2021: 8,650,741.
• Cropland acres added in 2022: 248,433.
• Non-cropland acres added in 2022: 603,654.
• Cropland acres removed in 2022: 4,659.
• Non-cropland acres removed in 2022: 20,506.
• Net change in 2022: 852,087 acres added.
• Total acres covered in 2022: 9,502,828.

Stoddard said most of the acres that were added were on the fringes of previously designated acres.
The groundwater protection rule has been in place since 2019.

Each year, some acres are added or removed because of nitrate levels in wells that provide drinking water to communities.

Minnesota Department of Agriculture

The map is updated by Jan. 15 of each year to give farmers plenty of time to plan for the fall, Stoddard said. An interactive map can be found on the Ag Department's website .
Stoddard added that while landowners are not notified individually, an awareness campaign will ramp up during the summer so landowners know about the restrictions.

Much of northwest Minnesota is exempted because of its climate while much of northeast Minnesota and some of the Twin Cities metro area is exempted because there is very little cropland there.

Nitrogen application also is restricted on frozen soil.

Stoddard said the restrictions align with the best management practices recommended by the University of Minnesota .

"The rule is new, but the advice is not," Stoddard said.