1. United States
2. Wash.
3. Letter

Nutrient pollution from fertilizers, particularly nitrogen-based fertilizers used in crop agriculture, is a major contributor to the growth of harmful algal blooms in waterways. Approximately half of the nitrogen and phosphorus applied as fertilizers ends up in the surrounding environment through runoff and volatilization. While best management practices have helped reduce some fertilizer runoff over time, excess nutrients still find their way into freshwater and marine ecosystems, fueling the proliferation of toxic algal blooms. Focusing efforts on further curbing fertilizer runoff from agricultural fields is essential to controlling nutrient loading and mitigating this environmental threat.