Which greenhouse gas is released from agricultural fertilizers?

The greenhouse gas released from agricultural fertilizers is nitrous oxide. When farmers apply nitrogen fertilizers to soil, microorganisms transform nitrogen compounds through processes such as nitrification and denitrification. Nitrous oxide (N₂O) can escape into the atmosphere, especially when soils contain excess nitrogen, water, or limited oxygen.

Agriculture is the largest human-related source of nitrous oxide. Synthetic fertilizers, manure, and nitrogen deposited on fields all contribute. Nitrous oxide is a powerful heat-trapping gas and also participates in chemical reactions that affect the stratospheric ozone layer. Its atmospheric lifetime is roughly a century, so emissions can influence climate long after they occur.

Ammonia is a nitrogen compound associated with fertilizer use, but it is not the principal greenhouse-gas answer here. Fertilized soils can also emit carbon dioxide and, under flooded conditions such as rice cultivation, methane. Those gases do not change the canonical answer: nitrogen fertilizer application is strongly associated with nitrous oxide emissions. More precise fertilizer use, improved timing, and better soil management can reduce these losses.