We need to talk about nitrogen

Exactly one hundred years ago, workers and engineers at the small town of Oppau near Ludwigshafen, Germany, were busy constructing a new factory that would start a more drastic change to global biogeochemistry than any other human intervention before or since. Towards the end of 9 , the chemicals company BASF had commissioned Carl Bosch to build the first industrial scale ammonia plant based on the procedure that Fritz Haber had developed in the lab at the beginning of the century, and which Bosch had managed to turn into a working technology in spite of severe doubts surrounding the feasibility of the high-pressure, high-temperature synthesis. The plant was designed to produce 30 tonnes of ammonia per day, and it duly started production in the spring of 9 4. Fifteen years earlier, the British Association’s president William Crookes had startled the world with his prophecy of global starvation due to the limits of agricultural production. Thanks to the nitrogen fertiliser produced with the Haber–Bosch process, the world could avoid this predicted apocalypse — though the process also served the production of explosives used in a different kind of apocalypse. Today, human activities produce more reactive nitrogen than natural processes, and around half the nitrogen found in the proteins and nucleic acids of the seven billion people alive today comes out of a Haber–Bosch plant. But will this massive human meddling with the nitrogen cycle, which even dwarfs the effects of industrialisation on the carbon cycle, including climate change, have any side effects that we may come to regret in the future? And do we even know what we’re doing to our planet by doubling its nitrogen throughput?