What is a consequence of relying heavily on chemical fertilizers in cotton farming?

Relying heavily on chemical fertilizers in cotton farming often leads to increased runoff, which can result in pollution. This occurs because excess fertilizers can wash away during rainstorms or irrigation, carrying nutrients such as nitrogen and phosphorus into nearby water bodies. This influx can cause eutrophication—an over-enrichment of water bodies leading to the excessive growth of algae, which depletes oxygen levels and harms aquatic life. Furthermore, such runoff can contaminate drinking water supplies, posing risks to human health and the environment.

In contrast, the other options do not align with the consequences of heavy reliance on chemical fertilizers. Improved soil microbiota would typically be associated with organic or sustainable practices rather than chemical inputs. Lower production costs are often not realized when high inputs of chemicals are balanced against potential environmental cleanup costs and soil degradation. Reduced pest populations may occur due to certain pesticides, but an over-reliance on chemical fertilizers can inadvertently lead to pest imbalances by favoring specific pest types that thrive in highly fertilized environments.