Farmland in the Upper Midwest, USA, planted to corn has increased significantly in the past decade due to a rush toward ethanol production for fuel. Much of this increase came from fields that were previously protected under the Conservation Reserve Program (CRP), a Federal land retirement incentive. This Geographic Information Systems (GIS) study quantifies these land changes in Minnesota, a northern state in the U.S. Corn Belt, prior to the past decade using 1997 and 2008 CRP GIS data layers for individual fields. Currently available CRP enrollment data by county masks significant changes occurring on a field-level scale, data which is no longer publicly available. Results suggest that marginal lands better suited for riparian wildlife habitat and surface water protection were plowed under in favor of industrial corn production. This was especially notable with fields in close proximity to refineries or those in drinking water supply management or groundwater contamination susceptibility areas. Federal ethanol mandates, farm bill policies, and high corn prices contribute to the pressure to farm these sensitive lands. Currently, CRP enrollments are capped at 9.7 million hectares, reduced from a long-standing 13-million-hectare cap by the 2014 farm bill. Discussions are now underway in the U.S. Congress to craft the 2018 farm bill and farming and conservation interests are strongly urging the Federal government to restore the 13-million-hectare enrollment cap. Ecosystem functions and benefits are optimized when conservation efforts are maintained over long periods and not interrupted by short-term political or economic trends.