Perspectives on the Nitrogen Cycle
A new analysis of pre-industrial biological N fixation suggests that these background rates may have been as low as ~50 Tg of N per year - 2.5-4 times less than the most widely used estimates. If the new estimate is accurate, the current magnitude of human alteration of the terrestrial N cycle has been understated. At the same time, anthropogenic fixation of N is accelerating in rapidly developing economies – most notably China, which now uses 50% more N fertilizer than the US and the EU combined. Several Chinese research groups are working to develop ways to reduce the N-intensity of intensive agricultural production in China and other rapidly developing economies. Finding ways to increase yields on a static land base while reducing levels of environmental damage that are already devastating represents a compelling scientific challenge and would be a substantial contribution to human well-being.