What is an effect of over-fertilizing crops?

Over-fertilizing crops can lead to increased nutrient runoff, which significantly impacts water quality. When excessive fertilizers are applied, particularly nitrogen and phosphorus, they can wash off the fields during rain events and enter nearby water bodies. This runoff contributes to nutrient pollution, which can stimulate algal blooms in lakes and rivers. The resulting algal growth can deplete oxygen levels in the water, leading to dead zones where aquatic life cannot survive, and can also produce toxins that are harmful to fish, wildlife, and even humans.

In contrast, while decreased soil erosion and reduced water retention can occur in specific contexts, they do not directly result from over-fertilization and are less relevant to the immediate environmental impact. Improved crop yields may occur to some extent upon initial application of fertilizers, but over-fertilization often leads to diminishing returns, plant stress, and greater susceptibility to disease, thus undermining overall agricultural sustainability. Focusing on nutrient management that aligns with crop needs is essential to prevent these negative consequences.