Nitrification and denitrification . The essential components of the nitrogen cycle are these two microbiological processes. Nitrates in soil are taken up by plants, which convert them into useful organic compounds, such as proteins. Animals in turn get most of their nitrogen-containing nutrients by eating plants or other animals that have eaten plants. Denitrification takes place when bacteria and fungi decompose protein and other nitrogen-containing compounds from plant and animal waste back into nitrogen gases, which are released to the atmosphere to begin the cycle again.
Humans intervene in the nitrogen cycles in various ways.
Land use disturbances, agricultural activity, fossil fuel burning and nitrogen fertilizer application all influence the rate of release of nitrogen-containing gases. Policy based on the idea that the problem of global climate change is linked to other critically important problems of environment and development. The combined risks are serious enough, and the eventual benefits of action great enough, to require urgent and bold initiatives, even if they impose a substantial immediate cost. The benefits will include experimentation, foresight, and cost-effective prevention. All of these are playing increasing roles in climate change-related deliberations.