How did this happen?
While the term "carbon footprint" is infamously well-earned, it overshadows its partner in crime—nitrogen. Carbon footprint is a measure of greenhouse gas emissions caused using fossil fuels, but there is no similar measure for understanding the impact that nitrogen has on the environment when used in food production.
WHAT HAPPENS?
Overuse of nitrogen in farming causes eutrophication - how nutrients in a body of water cause the dense growth of plant life, leading to the death of animal life due to a lack of oxygen. This overuse results in toxic algal blooms, fish suffocating, tainted drinking water supplies, and aquatic ecosystems crashing - all direct consequences of using nitrogen in agricultural production. Carbon alone is environmental public enemy number one, but nitrogen deserves its own ignominious title as its release into the environment wreaks havoc, causing terrible consequences to our waters.
THE HISTORY: HOW WE GOT INTO THIS
At the end of the second agricultural revolution, nitrogen-based fertilizers took off, increasing crop yields in an explosive manner. While this surge in food production has been effective in feeding a global population, it has also had significant unfavorable effects that we now understand. Such extreme amounts of nitrogen are used in farming that they exceed the soil’s ability to absorb and hold this fertilizer. The excess nitrogen runs off into rivers, streams, and eventually, lakes and oceans.
WHERE IT ENDS UP & THE EFFECTS
The nitrogen and other nutrients contained in the agricultural runoff fuel massive algal blooms. When these blooms become prevalent in bodies of water, they turn the water opaque and limit light penetration while they grow. The algal blooms block sunlight from reaching plants that grow at the bottom of lakes and oceans, effectively killing them off. As oxygen-producing plants die off, the amount of oxygen in the water depletes. When these algal blooms eventually die and sink to the bottom, bacteria consume the dead algae, and in the process consume much of the remaining dissolved oxygen in the water.
The rapid depletion of oxygen levels caused when plants die and oxygen-consuming bacteria feeds on them—a process called hypoxia—produces “dead zones.” Plants, however, are not the only victims in these dead zones. Fish and other marine life require the oxygen dissolved in water to survive. While fish may be able to abandon the dead zone by swimming away, other plants and animals end up dying, leaving the area barren.
IT'S A GLOBAL PROBLEM WITH MASSIVE IMPLICATIONS
Dead zones resulting from human activity exist all over the world. In the United States, these dead zones can be commonly found in lakes such as the Great Lakes and in coastal ocean environments such as the Gulf of Mexico and the Chesapeake Bay. In fact, the Mississippi River watershed at the mouth of the Gulf of Mexico has been estimated to contain the second largest dead zone in the world.
WHAT CAN WE DO?
One way to tackle the “dead zone” crisis is to prevent fertilizer runoff. As Jenny Howard of National Geographic puts it “The best way to accomplish this … is to encourage retaining nutrients at their original source—on land. This is done through better farm management practices, like using less fertilizer and using crop covers to help anchor soil in place.” In other words, there is a need to capture public enemy number two—nitrogen—in much the same way we need to capture carbon for the sake of our environment.
