A state Groundwater Protection Rule restricting the application of nitrogen fertilizers in the fall and on frozen soil goes into effect on Sept. 1.

According to a news release from the Minnesota Department of Agriculture (MDA), the rule applies to areas vulnerable to groundwater contamination, including Drinking Water Supply Management Areas with elevated nitrate levels and areas with coarse textured soils, karst geology and shallow bedrock.

Approximately 12-13 percent of Minnesota’s cropland is considered vulnerable.

A map showing the areas affected by the fall restriction shows a high concentration of vulnerable areas in Hubbard County and adjacent parts of Clearwater, Becker, Wadena and Cass counties.

Links to a pre-recorded video about the fall restrictions and a webinar presented on Aug. 12 are available here.

The rule was proposed in 2018 and approved in 2019 following a statewide series of hearings. For more information about the Groundwater Protection Rule, click here.

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Is manure included?

Annette Olson with the Hubbard County Soil and Water Conservation District shared advice she received from Larry Gunderson with MDA Pesticide and Fertilizer Management about whether the rule applies to fall manure usage. Gunderson wrote that the fall restrictions do not include manure unless it is considered a fertilizer.

“Manure is considered fertilizer if it is manipulated and sold for its nutrient content,” he wrote. “Manipulation of manures is generally done to change the physical characteristics (by drying, grinding, pelleting, etc.) so that it can be marketed and sold. Manipulated manures are considered fertilizers and are regulated by the MDA.”

For a Minnesota Pollution Control Agency guide to manure application, click here.