Minnesota farmers face new nitrogen fertilizer restrictions

PIERZ, Minn. (AP) — Farmers in parts of Minnesota face new regulations starting Tuesday on how they apply nitrogen fertilizer.

The Groundwater Protection Rule, developed by the Minnesota Department of Agriculture, took effect in June to tackle nitrate contamination in the state’s groundwater. But the restrictions on when farmers in specific areas can apply fertilizer began Tuesday.

The restrictions prohibit farmers from applying nitrogen fertilizer in the fall or on frozen ground, in parts of Minnesota where the groundwater is vulnerable to contamination. The regulation applies to nearly 12% of the state’s cropland, mainly in the central and southeastern parts of the state.

Nitrogen applied in the fall on coarse soil or karst bedrock is more likely to run off or seep into the groundwater before it can be used by crops planted in the spring, Minnesota Public Radio News reported.

Nitrate contamination comes from various sources, including septic systems and urban drainage. In Minnesota, however, the largest source is the fertilizer and animal manure typically applied on farmland.