What is a common consequence of using too much fertilizer in an agricultural setting?

Using too much fertilizer in an agricultural setting often results in increased nutrient runoff. This occurs when excess fertilizers, particularly nitrogen and phosphorus, do not get absorbed by the plants and instead wash away during rain events or irrigation. This runoff can lead to serious environmental issues, such as water pollution, which can cause algal blooms in nearby water bodies, leading to degradation of aquatic ecosystems.

In contrast, the other options represent outcomes that would not typically result from excessive fertilizer application. For instance, while it might be expected that improved plant health would follow the use of fertilizers, over-fertilization can actually harm plants by causing nutrient imbalances or toxicities. Enhanced pest resistance may be diminished, as overly vigorous plant growth can sometimes attract more pests or lead to weaker plants that are less resistant to attacks. Finally, rather than reducing weed growth, excess nutrients can encourage weed proliferation alongside the target crops. Thus, the primary consequence of over-fertilizing agriculture is indeed increased nutrient runoff.