Nitrous oxide:
a powerful greenhouse gas
300 times more powerful than carbon dioxide, but rarely addressed
Agriculture releases the majority of nitrous oxide emissions
In the U.S., more than 6 percent of total greenhouse gas emissions come from nitrous oxide. While this may seem small, nitrous oxide is a very powerful greenhouse gas – it lingers in the atmosphere for over 100 years and is almost 300 times more powerful than carbon dioxide. It is also the biggest threat to the ozone layer.
Agriculture produces over three-fourths of total U.S. nitrous oxide emissions. The greenhouse gas is emitted primarily from farmland soils, because of the extensive use of fertilizer on crops. Smaller amounts of nitrous oxide emissions come from livestock manure. The industrial production of fertilizers also produces nitrous oxide emissions.
When fertilizers are used on crops, nitrogen the plants don’t use can be converted into nitrous oxide by microbes in the soil.
Many factors influence levels of nitrous oxide emissions, from soil moisture to how often a farmer tills the soil. The timing, type, placement and amount of fertilizer applied to farm fields can also have a big impact on emissions.
Fertilizing corn plays an outsize role in these emissions. As these maps show, nitrous oxide emissions overwhelmingly come from the Corn Belt.
Figure 1
After a century of increasing fertilizer inputs, croplands now release more nitrous oxide emissions than ever.
Average annual direct soil N2O emissions (g N m-2 year -1) across the contiguous United States in the 1900’s, 1960’s, 1990’s and 2010’s. Source: data from Lu et al. (2022).
Figure 2
Nearly 12 million tons of nitrogen fertilizer are applied to farmland every year.
Source: Our World in Data using data from Food and Agriculture Organization of the United Nations (2023).
Farmers can use conservation practices to reduce nitrous oxide emissions.
Many practices, including changing the type, amount, and timing of fertilizer applications, can reduce agriculture’s nitrous oxide emissions.
