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Lupins and Lime Limit Grain Greenhouse Gas

20 August 2012

AUSTRALIA - Adding lime to soil or planting lupins can significantly decrease greenhouse gas emissions from grain production. That’s one of the findings from an Australian Government funded research project investigating new approaches that can decrease carbon dioxide (CO2) and nitrous oxide (N2O) emissions from cropping systems.

Julie Gaglia from the Department of Agriculture, Fisheries and Forestry said the Nitrous Oxide Research Program (NORP) was part of the Australian Government’s Climate Change Research Program – a significant research effort to provide practical solutions for agriculture to adapt and respond to a changing climate.

“The results of NORP provide land managers with information they can use to build more resilience in their enterprises,” Ms Gaglia said.

Associate Professor Louise Barton from the University of Western Australia’s Institute of Agriculture said nitrous oxide gas is emitted naturally from the microbial processes in the soil.

“Additionally, nitrogen fertilisers, manure and burning crop stubble can all increase mineral nitrogen in the soil, which in turn can increase the rate of nitrous oxide emitted,” Associate Professor Barton said.

“Given that nitrous oxide is around 300 times more potent than carbon dioxide, we need to identify practical and affordable strategies that farmers can use to decrease the impact of nitrogen fertiliser use on greenhouse gas emissions.”

Grain production is considered to be a net producer of greenhouse gases via fertiliser, herbicide and farm machinery use and production. Applying urea fertiliser can contribute up to 80 per cent of the total on–farm emissions.

“When urea is applied to the soil it releases carbon dioxide, plus the urea contains nitrogen that can stimulate those soil biological processes that result in nitrous oxide emissions.

“If we can use nitrogen fertilisers that do not release carbon dioxide when it is applied, or decrease growers’ reliance on urea by incorporating plants in the cropping rotation that fix atmospheric nitrogen, we may be able to decrease greenhouse gas emissions from grain production,” Associate Professor Barton said.

“Our work at Wongan Hills in Western Australia during the two–year study indicates that liming can decrease nitrous oxide emissions by 30 per cent, but only if the soil received nitrogen fertiliser during winter cropping.

“Further research is required to verify if liming decreases nitrous oxide emissions from other soil types across Australia.”

Research indicates that incorporating grain–legumes, such as lupins, into cereal rotations can also lower nitrous oxide emissions.

“Grain legumes are known to increase residual soil nitrogen, thereby decreasing the amount of nitrogen fertiliser you need to apply the following year,” Associate Professor Barton said.

“Growing lupins prior to wheat often benefits the subsequent wheat yields.

“Fertiliser is expensive, so if we can decrease greenhouse gas emissions and save money without adversely impacting on productivity, it’s a win–win for everyone.”

TheCropSite News Desk

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