In the United States, agriculture accounts for almost 70 percent of all nitrous oxide emissions linked with human activity. Nitrous oxide is one of the major gases contributing to human-induced climate change; it has a lifetime in the atmosphere of more than 100 years. In addition, a molecule of nitrous oxide has more than 300 times the heat-trapping effect in the atmosphere as a molecule of carbon dioxide.
In soils, the production of nitrous oxide through microbial activity is a natural process. By applying large amounts of fertilizer, however, humans have greatly increased the amount of nitrous oxide in soils. This is particularly true when nitrogen fertilizer is added in larger amounts than the crop needs, and when it is applied at times or in ways that make it difficult for the crop to get the full benefit.
"Improving the efficiency of nitrogen use for field crop agriculture holds great promise for helping mitigate climate change," Robertson says.
The nitrous oxide greenhouse gas reduction methodology, which is a way for farmers to participate in existing and emerging carbon markets, recently was approved by the American Carbon Registry and is in its final stages of validation by the Verified Carbon Standard--two carbon market standards that operate worldwide.
When farmers reduce their nitrogen fertilizer use, they can use the methodology as a means of generating carbon credits. These credits can be traded in carbon markets for financial payments.
The scientific underpinning for the methodology rests on decades of research Robertson and colleagues have conducted at the KBS LTER site.
"By closely following nitrous oxide, crop yields and other ecosystem responses to fertilizers," Robertson says, "we discovered that nitrous oxide emissions increase exponentially and cons
|Contact: Cheryl Dybas|
National Science Foundation