Minnesota phosphorus loss: How soil quality is only part of the story and why modeling it can be improved by considering subsurface phosphorus flows

This study explores 20 years of nutrient management data to identify how changing trends in cropping and fertilizer applications have affected phosphorus (P) loss risk across the state of Minnesota. Nutrient loading and farm management records from 1999 to 2019 were compiled across 18 different Minnesota counties representing five different state regions, including but not limited to data from Discovery Farms Minnesota, Minnesota Department of Agriculture, Minnesota Agricultural Water Resource Center, and the University of Minnesota. The consolidated data cover two critical watersheds in nutrient management, one flowing north to Canada's Lake Winnipeg, the other flowing south through the Mississippi River ultimately to the Gulf of Mexico. Best management practices are needed for P loss within these watershed basins due to rising concerns about recurrent harmful algal blooms in both watersheds. This study combines historical nutrient loading data and farm management data to see how soil quality impacts P loss.

In partial fulfillment of the requirements for the M.S. degree in the Graduate Program in Land and Atmospheric Science