Reducing nitrate in surficial sand aquifer, Mower County

Steve Lawler, Tim cotter, Jim Kellogg, Alan Slowinski

Commodity crop production in Minnesota is under scrutiny to reduce impacts of nitrogen fertilizer on groundwater. There is an extensive body of research documenting fertilizer as a source of nitrate in groundwater ( . The revised Minnesota Nitrogen Fertilizer Management Plan, finalized by the Minnesota Department of Agriculture in March of 2015, recommends specific best management practices in South Central Minnesota to reduce nitrate leaching from nitrogen fertilizer. The incorporation of cover crops in commodity crop production has also potential to reduce nitrate leaching in soil water (Staver, 1998). Cover crop technology is evolving towards multi-species mixes of annual and winter hardy plants inter-seeded into established commodity crops to extend growth during the growing season. However, the potential of inter-seeded covers to scavenge excess nitrates in a corn/soybean rotation in Minnesota is not well known.
Sustainable Answer Acre is a proposed study area provided by Northern Country Coop (NCC) of Lansing, Minnesota. In collaboration with Riverland College (RC) – Austin, University of Minnesota (UMN) and Mower SWCD, Northern Country Coop and local farmer/producers will establish multi-year replicated trials at Sustainable Answer Acre consisting of nitrogen BMPs (University of Minnesota Extension publication “Best Management Practices for Nitrogen Use in South-Central Minnesota”) in unison with cover crop technology.
The goal of this study is to quantify the effects and interaction of nitrogen application timing methods and cover crop management on NO3-N leaching potential. Located on sandy glacial outwash with groundwater at 10-ft below the surface, Sustainable Answer Acre and adjacent lands have been identified as potential groundwater vulnerable areas in the “Minnesota Nutrient Fertilizer Management Plan” (issued March 2015 by MDA). This site is well suited for evaluation of non-point source pollution from nitrogen fertilizer in groundwater.