Earth's growing nitrogen threat

Dennis Lindsay still recalls the day four decades ago when his father, an Iowa farmer, began using nitrogen fertilizer on the family’s 160 acres. With nitrogen, the family’s corn crop suddenly grew much higher and stronger, and produced full ears and big harvests. When fed to their cows and pigs, that high-quality corn produced far more milk and meat. As a result, the family bought more livestock – and the farm grew. “I remember Dad bringing the neighbors over to see how much greener and better the quality of the stalk was,” Mr. Lindsay says. “It was a really big deal then.” Yet it’s also becoming clear that too much of a good thing can have a downside for the environment. The world is awash in man-made “reactive” nitrogen (the chemically active form), researchers say. While greening farms worldwide, much nitrogen washes into lakes, rivers, and the sea, causing rampant algae growth. More nitrogen billows from power-plant smokestacks, blowing in the wind until it settles as acid rain. Still other nitrogen gases remain in the atmosphere consuming the ozone layer. Nitrous oxide is nearly 300 times as potent as carbon dioxide – considered the leading cause of climate change – and the third most threatening greenhouse gas overall. Last year, reactive nitrogen was identified as one of nine key global pollution threats and second worst in terms of having already exceeded a maximum “planetary boundary,” according to a study reported in the journal Nature...read more