"Agriculture accounts for eight to 14 percent of all greenhouse gas production globally. We are showing how farmers can help to reduce this number by applying nitrogen fertiliser more precisely," said Phil Robertson of Michigan State University.

Nitrogen-based fertilisers spur greenhouse gas emissions by stimulating microbes in the soil to produce more nitrous oxide.

Nitrous oxide is the third most harmful greenhouse gas, behind only carbon dioxide and methane and also destroys stratospheric ozone.

The production of nitrous oxide can be greatly reduced if the amount of fertiliser crops need is exactly the amount that is applied to farmers’ fields.

“Simply put, when plant nitrogen needs are matched with the nitrogen that is supplied, fertiliser has substantially less effect on greenhouse gas emission,” Robertson noted.

The research also showed that more nitrogen fertiliser could be added to underfertilised crops in sub-Saharan Africa.

“Because nitrous oxide emissions would not be accelerated by fertilisers until crop nitrogen needs are met, more nitrogen fertiliser can be added to underfertilised crops with little impact on emissions,” Iurii Shcherbak, a researcher at Michigan State University, added.

Adding less nitrogen to overfertilised crops elsewhere, however, would deliver major reductions to greenhouse gas emissions in those regions.

The study appeared in the journal Proceedings of the National Academy of Sciences.