What is the consequence of over-application of fertilizers?

Over-application of fertilizers primarily leads to increased nutrient runoff, which is a significant environmental concern. When fertilizers are applied in excess of what crops can absorb, the surplus can wash away during rain events or irrigation, leading to runoff. This runoff can carry nutrients, particularly nitrogen and phosphorus, into nearby water bodies, causing problems such as eutrophication. Eutrophication leads to algal blooms, which can deplete oxygen in the water and harm aquatic life.

Moreover, while increased nutrient runoff is a direct consequence of over-fertilization, there are also other potential issues that can arise, such as soil acidification or decreased crop yield, but these are often indirect effects or take longer to manifest compared to the immediate impact of nutrients entering waterways. Improved soil structure is generally associated with good agronomic practices rather than excess fertilizer application. Thus, the most immediate and evident consequence of over-application is the increased nutrient runoff that disrupts ecosystems and water quality.