Why can fertilizer runoff from sugarcane fields harm nearby waterways?

Fertilizer runoff from sugarcane fields harms nearby waterways primarily by contributing to cultural eutrophication, a process that degrades aquatic ecosystems.12

When fertilizers containing nitrogen and phosphorus wash into rivers or lakes, these nutrients act as a catalyst for the rapid growth of algae and other microscopic organisms. This excessive growth, known as water blooms, creates several environmental hazards:31

• Oxygen Depletion: As these blooms die and decompose, the process consumes vast amounts of dissolved oxygen, leading to hypoxia—a state of low oxygen that can cause massive fish kills and the death of other aquatic life.31
• Light Blockage: Dense concentrations of algae on the water's surface prevent sunlight from penetrating deeper, which inhibits the growth of necessary underwater vegetation.1
• Ecosystem Degradation: The resulting murky, nutrient-rich conditions often support fewer species, disrupting the local food chain and damaging the overall health of the ecosystem.1

Because sugarcane requires significant fertilization throughout its growth cycle, managing runoff is essential to preventing these harmful impacts on surrounding water resources.2