Synthetic fertilisers major contributors to climate change

OSLO: The most widely-used synthetic fertiliser, it and its chemical cousins ammonium sulfate, sodium nitrate, and potassium nitrate are significant contributors to climate change.

Its production is energy-intensive, requiring the burning of fossil fuels. After farmers apply these synthetic fertilisers to crops, chains of chemical reactions generate nitrous oxide, or N2O, a greenhouse gas.

The International Fertiliser Association pegs the amount of anthropogenic GHG emissions for which the industry is responsible at 2.5%, but all greenhouse gasses are not created equal. N2O has a far greater global warming potential than either methane or carbon dioxide—265 times more by weight as CO2.

Even worse, “nitrous oxide emissions are higher than previously thought, and going up faster than previously thought,” said Rona Thompson, senior scientist at the Norwegian Institute for Air Research.

Green groups have been pushing for years to get farmers to reduce their fertiliser use, and many are starting to listen. “Emissions in the US and Europe have stabilized and started to go down, and farmers maintained or slightly increased yield while using no more nitrogen fertiliser,” Thompson said. Market factors have also influenced the reduction.