MPCA finalizes changes to feedlot general permits
In January, the Minnesota Pollution Control Agency (MPCA) finalized changes to the National Pollutant Discharge Elimination System (NPDES) and State Disposal System (SDS) feedlot general permits. The finalization came after a public comment period over the summer and subsequent revision by the agency.
Like the draft permits, the finalized permits require farms that accept transferred manure from permitted facilities to follow the same land application and reporting requirements as permittees. That includes adhering to the MPCA’s list of nitrogen best management practices (BMPs)—practices that vary depending on the time of year and whether a farm is located in a vulnerable groundwater area. Notably, in vulnerable groundwater areas, the only allowable nitrogen BMP from Oct. 1-14 is application to a growing perennial or row crop or planting a cover crop prior to or within 14 days of application.
Farms that accept transferred manure from permitted facilities also must provide the permit-holder with manure application records that include crop information, total nutrients applied, and soil test results. They must also adhere to the same visual inspection requirements mandated for permitted facilities.
In comments this summer, MCGA’s agriculture partners urged the agency to reconsider allowing only cover crops as a nitrogen BMP from Oct. 1-14 in vulnerable groundwater areas. They noted research showing that later-planted cover crops have much less potential to reduce nitrate leeching in Minnesota due to the state’s shorter growing season. In a four-year, replicated study at the University of Minnesota Southern Research and Outreach Center, for example, weather permitted adequate cover crop growth to allow for a significant reduction in nitrates in only one year. Other research has shown that the lack of precipitation for more than a week after cover crop seeding often results in their poor establishment.
MCGA’s ag partners also noted how narrowing the window of available days for manure applications could also lead to negative management outcomes due to poor early crop growth due to soil compaction and the inability to avoid runoff-inducing rainfall events, which could all lead to a loss of yield and potentially increase nitrate leaching. For example, an unintended consequence of spring application is soil compaction which could create nutrient runoff rather than allowing nutrients to soak into the soil. Additionally, limiting fall applications would require livestock farmers to increase manure storage capacity to buffer against weather delays that disrupt application plans, which would require significant investment that might not be feasible for all producers.
MCGA’s ag partners also noted how the MPCA does not have the authority through the permit process to extend its reach to recipients of transferred manure. They said the permit does not cover a purchaser of manure and that the new rule places an undue burden on permitholders to collect information that’s beyond their purview.
About MN’s feedlot permitting program
State law requires all feedlots with more than 1,000 animal units to obtain an SDS permit, while federal law requires 1,000-plus-animal-unit feedlots that discharge into waters of the U.S. to obtain an NDPES permit. In Minnesota, the NPDES permit can serve as a stand-in for the SDS permit. That’s the route taken by about 80% of the state’s 1,000 permitted facilities. (In total, there are about 17,000 feedlots in Minnesota.)
The new state SDS general permit will become effective on June 1, 2025, and the new federal NPDES general permit on Feb. 1, 2026. As part of the new permits, the MPCA will also require applications to use a new online Nutrient Management Tool to develop manure management plans (MMP) and submit MMPs electronically to them as part of the application process.
Learn more about the new permit requirements at here.
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Additional information
Nitrogen BMP requirements under Minnesota’s new NPDES/SDS permits
Vulnerable groundwater areas
June 1-Oct. 14
Must meet one of the following conditions:
- A cover, perennial, or row crop is growing
- Or a cover crop will be planted within 14 days of application
Oct. 15-31 (beginning 2027)
Must meet one of the following conditions:
- A cover, perennial, or row crop is growing; or a cover crop will be planted within 14 days of application
- The soil temperature has reached 50 degrees for two straight days, and a perennial is growing two out of five years
- The soil temperature has reached 50 degrees for two straight days, and a nitrapyrin-based nitrification inhibitor is used with application (liquid manure)
- The soil temperature has reached 50 degrees for two straight days, and split application of no more than 1/2 of the nitrogen needs (solid manure)
Nov. 1-30 (beginning 2027)
Must meet one of the following conditions for liquid manure application:
- A cover, perennial, or row crop is growing; or a cover crop will be planted within 14 days of application
- A perennial is growing two out of five years
- A nitrapyrin-based nitrification inhibitor is used with application
Outside of vulnerable groundwater areas
June 1-Sept. 30
Must meet one of the following conditions:
- A cover, perennial, or row crop is growing
- Or a cover crop will be planted within 14 days of application
Oct. 1-14
- A cover, perennial, or row crop is growing; or a cover crop will be planted within 14 days of application
- The soil temperature has reached 50 degrees for two straight days
- A nitrapyrin-based nitrification inhibitor is used with application
- Split application of no more than 1/2 of the nitrogen needs
Oct. 15-Nov. 30
Best management practices outside of vulnerable groundwater areas are encouraged but are not required.
Winter application restrictions
The requirements are the same both in and out of vulnerable groundwater areas.
From Dec. 1-March 31, liquid manure application is prohibited on frozen or snow-covered fields. From Dec. 1 Feb. 29, solid manure can only be applied to frozen or snow-covered fields if a specific set of conditions are met. Those conditions can be found online. Solid manure application is prohibited on frozen or snow-covered fields in March.
If winter conditions do not exist at the time of application during the months of December through March, land application is allowed provided the manure is injected or incorporated within 24 hours.
