What is a major consequence of excessive nitrogen use in agriculture?

Eutrophication is recognized as a major consequence of excessive nitrogen use in agriculture due to the way nitrogen compounds behave when they enter aquatic ecosystems. When nitrogen from fertilizers and manure runoff into waterways, it leads to an over-enrichment of nutrients in the water, promoting excessive growth of algae, known as algal blooms. These blooms can deplete oxygen in the water when the algae die and decompose, leading to "dead zones" where aquatic life cannot survive. This process adversely affects water quality and impacts ecosystems, posing significant challenges for fish populations and other aquatic organisms.

Other effects, such as soil acidification, lower soil fertility, and pest resistance, can occur due to nitrogen imbalances. However, eutrophication specifically highlights the direct link between nitrogen application and environmental harm, making it a critical consequence of nitrogen misuse in agricultural practices.