Over the past 50 years fertiliser use has contributed to the rise in atmospheric nitrous oxide levels

University of California, Berkeley, chemists in the US have shown that increased fertiliser use over the past 50 years has contributed to the rise in atmospheric N2O levels. Nitrous oxide is a major greenhouse gas, but although scientists assumed the increased levels of the gas were caused by nitrogen-based fertilisers stimulating soil-based microbes to convert the nitrogen to N2O, evidence to back up this claim was sparse.

The study, published in Nature Geoscience (DOI: 10.1038/ngeo1421) used isotopic ratios to identify the fingerprint of fertiliser in air samples taken from Antarctica and Tasmania. The researchers admit that, while fertiliser use can’t be ended, they hope that their findings will contribute to changes in agricultural practice that will cut levels of N2O from farming.