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.