University of Minnesota research shows grassland-to-cropland conversion is contributing to groundwater contamination


Nick Fetty | August 14, 2014
A southern Minnesota farm just before harvest. (keeva999/Flickr)
A southern Minnesota farm just before harvest. (keeva999/Flickr)

Southeast Minnesota farmers converting their grassland into cropland could be contributing to increased nitrate levels in groundwater, according to researchers at the University of Minnesota.

The research estimates that it will cost between $700,000 and $12 million over the next 20 years to address increased nitrate levels in private wells throughout southeastern Minnesota. Researchers Bonnie Keeler and Stephen Polasky used biophysical models and economic valuation to draw their conclusions.

Between 2007 and 2012, more than one-quarter of grassland in southeastern Minnesota were converted into cropland. This led to higher amounts of fertilizer being used which then led to higher nitrate levels in waterways. This creates both health and financial risks for 70 percent of Minnesotans who rely on groundwater as well as for the 1 million residents who get their water from public wells.

The southeastern portion of Minnesota is especially vulnerable to groundwater contamination because of its karst geology which contains cracks and fissures in underground rock formations that can easily be penetrated and jeopardize the quality of the water. Researchers from the University of Minnesota and the University of Minnesota Extension found tillage to be the most effective method to protect water quality in southeastern Minnesota.

Both the Upper Iowa River and Cedar River Watersheds begin in southeastern Minnesota and travel down through portions of eastern Iowa before draining into the Mississippi River.

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