With several governments around the world pursuing limits on nitrogen fertiliser use in agriculture, how would farmers adapt if the Australian government took a similar approach?
In broadacre cropping, fertiliser production and use accounted for 58 per cent of the Australian wheat crop’s greenhouse gas footprint in the past five years, according to the Department of Agriculture.
Of that, 31 per cent occurred on-farm, a large part of which came from the use of nitrogen fertiliser.
The greenhouse gas nitrous oxide comes from the denitrification of nitrates in soils, and the pollutant ammonia comes the volatilisation of nitrogen fertilisers.
Nitrous oxide is almost 300 times more potent than carbon dioxide.
James Murray is senior research manager with the Birchip Cropping Group.
He said there were products available to slow the volatilisation process, which occurs when nitrogen is applied to a crop and there is insufficient rainfall following application to break it down.
“There are a couple of products on the market — one is a urease inhibitor, which reduces that volatilisation risk by slowing that release when you apply if you don’t get follow-up rainfall relatively quickly,” he said.
“The other one is a polymer coating, which slows the release of nitrogen quite significantly.
“But the challenge with them is they’re not necessarily cost-effective to utilise, with the urease inhibitor retailing for about $50 a tonne on top of your urea cost, so it opens up a question about how cost effective that is in the farming system.”
Mr Murray said whether or not farmers used a urease inhibitor, there was significant value in getting nitrogen application right and minimising volatilisation.
“We talk a bit about the four Rs — so the right rate, the right product, the right source and the right timing, which at the end of the day will have significant benefits for production, and if we’re reducing our greenhouse gas footprint at the same time, that’s a bonus,” he said.
