Carbon dioxide deserves most of the blame for trapping heat in the Earth's atmosphere, but it has accomplices. The third most common greenhouse gas in the atmosphere is nitrous oxide, which is about 300 times more effective at trapping heat than carbon dioxide.
The majority of the world's nitrous oxide emissions come from agriculture in the U.S. But researchers at the University of Missouri – Columbia have found a way to limit the greenhouse gas without making farmer's lives more difficult. In fact the technique can also help farmers save money and improve their yields.
"The main goal for our team has been to identify agricultural practices that maintain or increase production while reducing the environmental impact," said Peter Motavalli of the University of Missouri.
In the past, most farmers tilled whole fields, but that caused tremendous problems with erosion. The Dust Bowl was largely caused by over-tilling the easily eroded soils of the Great Plains. To avoid the fate of the Joad family in John Steinbeck's The Grapes of Wrath, American farmers changed their practices to better conserve the soil.
Now, many farmers do not till their fields, but this increases fertilizer run-off. Also, when soil bacteria finds a tasty combination of nitrogen fertilizer and oxygen on the surface, they eat it up and release nitrous oxide.
The university researchers experimented with the technique of tilling strips of the field about a foot wide and eight to nine inches deep. This allows farmers to use less gas in their tractors while still leaving crop residues, like corn stalks, on the field's surface to prevent erosion.
When farmers till strips and apply fertilizer into the soil of the furrows, the nitrogen fertilizers don't run off and pollute waterways. It also improves yield since more fertilizer gets to the plants.
Here's where the climate benefits come in. By placing the nitrogen fertilizer into the furrows, less of the chemical is converted into nitrous oxide by air-breathing soil microbes.
The researchers conducted their study in northeast Missouri from 2008 to 2010. One field was "strip tilled" with nitrogen fertilizer placed in a band in the soil, while another field was left untilled with a surface application of nitrogen fertilizer.
PHOTO 1: A farm in northwest Missouri; Wikimedia Commons.