Breakthrough could help slash agricultural emissions

The breakthrough involves a fresh approach to chemically converting reactive nitrogen common in soil before it turns into a harmful greenhouse gas. Photo / File

A discovery by Kiwi and US scientists could lead to new ways for New Zealand's agricultural sector to slash greenhouse gas emissions.

The breakthrough involves a fresh approach to chemically converting reactive nitrogen common in soil before it turns into a harmful greenhouse gas.

The New Zealand scientists - Landcare Research's Rebecca Phillips, Andrew McMillan, Gwen Grelet, Bevan Weir and Palmada Thilak - discovered that reactive nitrogen (N) could be chemically converted to unreactive di-nitrogen gas (N2) without forming the harmful greenhouse gas nitrous oxide (N2O).

This was important because agriculture contributed more N2O than any other sector worldwide - primarily through nitrogen fertilisation.

This greenhouse gas was 300 times more effective at trapping heat in the atmosphere than carbon dioxide and 10 times more effective than methane.

N2O also moves into the stratosphere and destroys ozone.

The team were the first to report organic N can react with inorganic N to create hybrid N2 under standard conditions of temperature and pressure.

Until now, it was thought this was only possible biologically.

N2 makes up 78 per cent of our atmosphere and is considered a permanent sink for nitrogen.

The discovery could lead to new opportunities for mitigating excess reactive N in the environment and Phillips believed the research set the stage for many practical applications.

Organic forms of soil N, such as exudates from plants and fungi, could function in the conversion of excess inorganic N that would otherwise be leached into water or emitted as N2O into a form that isn't harmful to the environment.

However, more research is needed to test exactly which forms of organic nitrogen were most effective.

The team is now developing proposals for further funding that will allow them to investigate on-farm applications for transforming excess N from soil and water into unreactive atmospheric N2 gas without producing N2O.

This may allow scientists to develop options to manage the fate of agricultural N while avoiding greenhouse gas emissions.

The research features in the latest edition of the scientific journal Nature Scientific Reports.