Nitrogen deposition reduces the amount of carbon dioxide emitted from temperate forest soils, according to a review published online this week in Nature Geoscience.

Fossil fuel and fertilizer use has increased the amount of nitrogen in the atmosphere over the past century, leading to increased levels of nitrogen in soils.

Ivan Janssens and colleagues carried out an analysis of nitrogen addition experiments and field studies to determine the impact of nitrogen deposition on soil carbon turnover in temperate forest soils. They find that nitrogen deposition slows the breakdown of soil organic matter, and increases soil carbon storage. As a result, carbon dioxide emissions from soil are substantially reduced.

The researchers warn that the future increase in nitrogen deposition expected in the tropics could have unforeseen consequences for carbon cycling in tropical forest soils.