World’s predominant nitrogen fertilizer induces extreme eutrophication of surface waters in central North America

Nature Water, Published online: 15 April 2026; doi:10.1038/s44221-026-00636-7 Urea, the most widely used nitrogen fertilizer, has unknown impacts on freshwater ecosystems. This study demonstrates that urea additions in Canadian prairie agricultural reservoirs triple phytoplankton abundance without increasing cyanobacterial toxins, revealing considerable nitrogen loss to the atmosphere and highlighting potential global water quality degradation in phosphorus-rich agricultural regions.