Nitrous oxide, climate change and agriculture

Nitrous oxide is an important greenhouse gas with a global warming potential of 298 times that of carbon dioxide. It is also responsible for the destruction of stratospheric ozone. Concentrations of nitrous oxide have shown continuous growth in the atmosphere over the past century, and nitrogen (N) fertilizers and manures applied to agricultural soils are the main anthropogenic source. Precise measurements of emissions from soils are difficult to undertake, as a consequence of high levels of spatial and temporal variability. For this reason, national reports on emissions are based largely on an assumption that a fixed fraction of N is released from N use in agriculture. Attempts to reduce nitrous oxide emissions, resulting from the use of N fertilizer, conflict with the need to maintain or increase food production and to support a growing world population. There is a large regional variation in the growth of emissions, with Asia contributing to the largest growth rates. More efficient management of N fertilizer and improved soil management (particularly in Asia) offer the opportunity to reduce emissions whilst maintaining food production.