Soil carbon study to test nitrogen gas risk

A study led by The University of Western Australia (UWA) is investigating whether increasing soil carbon in grain production to offset greenhouse gas emissions may also increase nitrous oxide emissions, which are nearly 300 times more damaging than carbon dioxide.

The project is based in WA’s grain belt and funded by the Commonwealth Government’s Filling the Research Gap project, which forms part of its Carbon Farming Futures program, in partnership with the Grains Research & Development Corporation (GRDC), the Department of Agriculture and Food WA (DAFWA) and the Liebe Grower Group.

UWA researchers will examine whether there is a risk that increasing soil carbon will also increase soil nitrous oxide emissions and burden farmers with additional nitrogen fertiliser requirements for cropping soils.

“Increasing carbon in soil is promoted as a means of offsetting greenhouse emissions from grain production; however, we need to check that this benefit is not negated by increased soil nitrous oxide emissions or additional nitrogen fertiliser requirements,” said Associate Professor Louise Barton, from UWA’s Soil Biology Group and the UWA Institute of Agriculture.

“Nitrous oxide is a particularly potent greenhouse gas as it is almost 300 times more damaging than carbon dioxide, so it is crucial that we ensure emissions of this gas from agricultural soils are minimised. Furthermore, nitrogen released from the soil into the atmosphere represents a loss of N fertiliser available to crops.”

The three-year study has been established at Buntine - about 250 km from Perth - where the Liebe Grower Group has successfully increased soil carbon as part of a previous research project which commenced in 2003. Nitrous oxide emissions will be measured at the Liebe Group’s Long Term Soil Biology Trial using an automated chamber system. At the same time, crop responses to nitrogen fertiliser will be measured in experimental plots of contrasting soil carbon and be compared further with data from other sites in the Western Australian grain belt.

“The trial site at Buntine provides a unique opportunity to study the effect of increasing soil carbon on other greenhouse gas emissions and we are very pleased to have the opportunity to work with the Liebe Group,” Associate Professor Barton said.

Results from the study will be used to inform growers and policy on the effects of increasing soil carbon on the carbon footprint of grain production in Western Australia.