What negative effect can result from excessive pesticide application?

Excessive pesticide application can lead to the pollution of nearby waterways. When pesticides are applied in larger quantities than necessary, they can runoff during rain or irrigation. This runoff can carry harmful chemicals into lakes, rivers, and streams, leading to contamination of aquatic ecosystems. Such pollution can harm wildlife, disrupt aquatic life cycles, and even affect human health through drinking water supplies. Managing pesticide use carefully helps to mitigate such risks and protect the surrounding environment.

In contrast, the other outcomes listed do not result from excessive pesticide usage. For instance, improved plant respiration and enhanced biodiversity are characteristics that would ideally benefit from balanced use of pesticides, not excessive application. Additionally, soil nutrient depletion is more directly associated with factors such as poor soil management practices rather than solely with pesticide use. Therefore, the significant concern regarding runoff and its impact on local waterways underlines the importance of responsible pesticide application.