NITROUS oxide is well known in hospitals and dental practices as an anaesthetic laughing gas but on farms, it is a serious problem.
A by-product of the breakdown of nitrogenous fertilisers, nitrous oxide also happens to be one of the most damaging greenhouse gases affecting global climate change.
It is 300 times more potent in warming the earth than carbon dioxide, on a molecular basis.
According to Queensland University of Technology professor Peter Grace, nitrous oxide accounts for 20 per cent of Australian agriculture's greenhouse gas emissions and about 5 per cent of national emissions.
Prof Grace said the main source of nitrous oxide emissions from farms was volatilisation of nitrogenous fertilisers, such as di-ammonium phosphate, ammonium nitrate and urea, into the air.
The Grains Research and Development Corporation is co-ordinating eight research projects across Australia looking at ways to reduce nitrous oxide.
Three of those projects are being carried out in Victoria, including one run by the Department of Primary Industries that looks at gas emissions from wheat and pulse rotations in high-rainfall regions.
Project leader John Graham, of the DPI's Hamilton office, said previous research had shown high nitrous oxide emissions after significant rain, when wheat had followed a perennial ryegrass-legume pasture - a common situation in the Western District.
"When the soil wets up, you get high nitrous-oxide levels," Mr Graham said.
"The soil goes into an anaerobic state and the soil bacteria get stressed because of the lack of oxygen. The bacteria process the nitrogen from artificial fertilisers into nitrous oxide."
Mr Graham said research had indicated the fixed nitrogen from pulse crops produced less nitrous oxide. Cultivation and use of nitrification inhibitors also appeared to reduce nitrous oxide levels.
"We are examining how tilling the soil impacts nitrous-oxide emissions and whether applying nitrification inhibitors can also reduce the emissions for high-rainfall cropping systems," he said.
"Initial results indicate that direct drilling decreases emissions, and inhibitors also decrease emissions, particularly on the conventionally sown plots that were cultivated before sowing."
Mr Graham said it was unclear how cultivating the soil resulted in lower gas emissions, but it was possibly because it aerated the soil, creating more active microbes which broke down nutrients.
He said the denitrification inhibitor being trialled in the Western District experiments was dicyandiamide, or DCD.
He said New Zealand research had shown use of DCD had resulted in more nitrogen fertiliser being converted into the ammonium form of nutrients, making it more available to plants.
"In New Zealand, they got an increase in plant growth," he said. "We are hoping for the same response here, with more crop growth and grain."
Mr Graham said the research at Hamilton used 12 automated chambers in crops, to capture and measure greenhouse gases.
