Nitrogen-Based Fertilizer Impacts the Climate: How Much is Too Much for Agriculture?

Improving farming is important for food security. Yet as agriculture intensifies, more fertilizer is being used to produce more crops. Now, scientists have taken a look at nitrogen-based fertilizers and have found out exactly how much is too much for the climate.

Nitrogen fertilizer can contribute to greenhouse gas emissions from agricultural fields. This, in turn, can impact the climate and cause temperatures to warm. These fertilizers spur gas emissions by stimulating microbes in the soil to produce more nitrous oxide, which is the third most important greenhouse gas behind carbon dioxide and methane. In addition, it also destroys stratospheric ozone.

In all, agriculture accounts for about 80 percent of human-caused nitrous oxide emissions worldwide. These emissions have increased significantly in recent years, mostly due to nitrogen fertilizer use. That's why scientists wanted to find out exactly how much these emissions were rising.

"Our specific motivation is to learn where to best target agricultural efforts to slow global warming," said Phil Robertson, one of the researchers, in a news release. "Agriculture accounts for eight to 14 percent of all greenhouse gas production globally. We're showing how farmers can help to reduce this number by applying nitrogen fertilizer more precisely."

In fact, the researchers examined data from around the world to show that emissions of nitrous oxide rise faster than previously expected when fertilizer rates exceed crop needs. In addition, they showed that the production of nitrous oxide can be greatly reduced if the amount of fertilizer the crops need is exactly what is applied.

The findings reveal that understanding exactly how much fertilizer to add to a field can greatly impact how much greenhouse gas emissions are released into the atmosphere. By adjusting fertilization, farmers can help lower the impact of these gas emissions and help our environment and our climate.