A large-scale analysis of global nitrous oxide emissions was published in the journal Earth System Science Data in June.

Pep Canadell, director of the Global Carbon Project and one of the study’s authors, said nitrous oxide is the third most important greenhouse gas after carbon dioxide and methane.

“The amount of greenhouse gases has increased dramatically over the last 200 years,” Canadell said, “and hence the warming and extreme weather events we are experiencing today.”

Numerous human activities have led to the accumulation of these gases in the atmosphere, Canadell said.

Savannah Adkins, a doctoral student in the biology department at Utah State University who studies the mechanisms of nitrogen and carbon cycling, said nitrous oxide can be produced by internal combustion engines, but the main sources of emissions in Cache Valley are agriculture.

Nitrous oxide is produced by microbes in the soil when there is an excess of nitrogen that is not used by plants.

“Nitrogen is an element that all living organisms need to function,” said Adkins. “Before the so-called Green Revolution, when modern fertilizers were created, there were few ways for organisms to obtain usable nitrogen.”

Although the invention of nitrogen fertilizers helped increase crop yields, it also led to the saturation of the soil with excess nitrogen.

Canadell said 70 percent of man-made nitrous oxide emissions come from agriculture.

“So not only do you need more fertilizer to eat more vegetables, you also need more fertilizer to grow more crops and feed more animals, because we want more meat and those animals need more fertilizer,” Canadell said.

Another source of these emissions is the accumulation of cow manure. Adkins said manure is very rich in nitrogen.

“When nitrogen accumulates in small areas, there are microbes in that fertilizer that eat the nitrogen and, because there is an excess of nitrogen, convert it into nitrous oxide,” Adkins said.

Canadell said the link between nitrous oxide and agriculture is one reason why this greenhouse gas has been so little studied.

“When we come together for these international negotiations to address climate change, many countries do not want to address this issue because this is about food security – you don’t want to do anything that makes your own system more vulnerable,” Canadell said.

Some countries have even subsidised the use of nitrogen under the pretext of increasing food production, Canadell said.

“And we’ve seen that this has led to major hotspots around the world where the amount of nitrogen that’s getting onto the fields is clearly way too high,” Canadell said. “These are things that can actually be fixed with the right measures.”

Canadell said actions can also be taken at the individual farm level. To achieve best practices, farmers should try to implement the “three Rs.”

“And by that I mean … the right amount of fertilizer in the soil, at the right time (that is, when the plants really need it) and at the right depth,” Canadell said.

Resources are available for Utah farmers who want to learn more about their soils and appropriate fertilizers.

“Through the USU Extension program, you can have your soil tests done and get help calculating your nitrogen needs, so you can avoid over-fertilizing with nitrogen fertilizer,” Adkins said.

To reduce nitrogen oxide emissions from livestock, Adkins said a manure management plan is important, especially for animals kept in confined spaces. Dairy farms produce a high concentration of manure in a small space because cows must be kept close by for daily milking.

“Compared to cattle on pasture, these cattle are migratory,” Adkins said, “and because they’re moving, their manure is more widely distributed, so it’s not as much of a problem.”

On undeveloped land where no fertilizers are used, the nitrogen from manure can actually support native plants.

“Cattle often get a bad rap, especially in the Intermountain West, but they don’t have to be bad,” Adkins said. “Cattle can be raised in a way that benefits ecosystems.”

There is currently no practical method to remove nitrous oxide from the atmosphere, Canadell said.

“That’s why the only solution is to reduce these emissions – they don’t have to go to zero, but they have to be reduced,” Canadell said. “Currently they continue to rise.”

To learn more about soil nutrient management and testing through USU Extension, visit https://extension.usu.edu/yardandgarden/soils.