The Negative Effects of Nitrogen-Rich Fertilizer to the Environment

Written by Bobbie Whitehead; Updated December 09, 2018

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Though nitrogen serves to aid plants in their growth, weeds and nonnative plants tend to grow more readily with additional nitrogen supplies. Other plants that have lower nitrogen needs end up dying, causing a decline in native species, according to the Ecological Society of America. In California, for example, the National Science and Technology Council reports that too much nitrogen encourages the growth of nonnative grasses and kills off lichens on trees. In the coastal areas of the western United States, soils have higher levels of nitrogen, which feed nonnative grasses. The shift in plant species increases the chances of wildfires because these new grasses are flammable, the ESA explains.

Soil Imbalance

In the soil, too much nitrogen also creates an imbalance of nutrients that causes a depletion of other important minerals such as calcium, phosphorus and magnesium. While fertilizer overuse causes this change, nitrogen-polluted air, caused by nitrates from automobiles and industrial plants, also results in this acidification of the soil when acid rain falls. When the nitrogen abundance reduces important minerals, toxic elements such as aluminum can proliferate and harm plants as well as fish in rivers.

Algae Growth

When nitrogen levels in rivers and streams increase, they aid in algae overgrowth. As algae dies and decomposes, organic matter in the water increases. This process uses up oxygen, causing levels to drop. Without the oxygen, fish, crabs and other aquatic life die. In the San Francisco Bay Delta, for example, blue-green algae blooms occur in numbers during the warmer months, especially when the conditions such as increased nitrogen occur, according to the California Department of Health. Researchers at the Woods Hole Oceanographic Institution say these algae blooms, which can appear in different colors, produce toxins that can be harmful.

Water Contamination

A soluble substance, nitrogen soaks deeply into the soil after a rainstorm or after irrigation, reaching ground water and nearby wells. When babies under a year old and elderly people ingest water with high nitrogen levels, they can develop symptoms such as gastrointestinal swelling and irritation, diarrhea, and protein digestion problems, according to the University of Nebraska-Lincoln Extension. These symptoms result from the condition methemoglobinemia, also called "blue baby syndrome," which occurs when nitrates mix with iron in red blood cells, leaving the blood unable to transport oxygen to the body's cells. Because nitrogen is odorless and colorless, only testing can determine whether contamination has occurred.