The production and use of nitrogen fertilizers accounts for 5 percent of global greenhouse gas emissions, which can be massively reduced with a few available interventions, a new study said on Thursday.
Nitrogen fertilizers — produced and used across the world —are crucial for global food security.
But their harmful emissions contributing to global warming exceed the aviation sector, and are on par with the iron and steel, cement and plastics industries.
Most existing research has focused on emissions associated with the production of fertilizers, but Thursday’s study showed that the majority — two thirds — come from the use of the fertilizers in croplands.
“There is the perception that the petrochemical industry has been causing the emissions producing the fertilizers, but actually that doesn’t seem to be the case. That was very surprising for us,” co-author Andre Cabrera Serrenho from Cambridge University told AFP.
The findings are important because they show “where we should prioritize action to reduce emissions,” he added.
Carbon emissions could be reduced by up to 80 percent by 2050 while still producing enough food to feed a growing global population, said the study published in the journal Nature Food.
“The interventions we propose in our study do not imply loss in crop productivity, and they consider the future growing demand for food to feed a growing global population,” Serrenho confirmed.
“We are currently really inefficient in the way we use fertilizers,” he said. “We put much more fertilizers in croplands than the amount of nitrogen that actually crops need to grow.”
The main emissions in the use phase come from the degradation of fertilizer by bacteria that exist in the soil and produce nitrous oxide, one of the most powerful greenhouse gases.
Carbon dioxide and methane are also emitted in the use phase, but simply using less fertilizer could help to slash those harmful emissions.
But convincing farmers to use fertilizers more efficiently — for example, applying them daily in smaller quantities instead of spraying in large doses them once a season — will require policy shifts.
“If we could have more economic incentives to farmers to change practices to reduce emissions, that seems to be the most obvious place to start,” Serrenho said.