A new $8 million national study is set to quantify greenhouse gas (GHG) emissions from crop residues, to help the Australian grains industry accurately report its carbon (C) footprint, with potential benefits for future market access and price.
An initiative of GRDC, the national project will be led by Professor David Rowlings from the Queensland University of Technology (QUT) and will involve two years of field work to quantify emissions from crop residue decomposition across a range of crop types, climates and soils at five sites in Australia.
The trial sites will be located at Gatton (Queensland), Tamworth and Wagga Wagga (New South Wales), Horsham (Victoria) and Wongan Hills (Western Australia). These trial sites will be co-ordinated and monitored by the project's research partners:
- Agriculture Victoria,
- the Western Australian Department of Primary Industries and Regional Development (DPIRD),
- the NSW Department of Primary Industries and Regional Development (NSW DPIRD),
- the University of Queensland (UQ).
The landmark study is expected to have significant benefits for grain growers and marketers, as the GHG emissions attached to grains can impact the price and marketability of exports, as well as the sustainability credentials of farm businesses.
Professor Rowlings said crop residues emit GHG as they decompose in the paddock, with nitrous oxide (N2O) making up most of these emissions.
"Australia includes these emissions in its sector level accounting to the Intergovernmental Panel on Climate Change (IPCC)," he said.
"While the global default emission decomposition factor is one per cent of total residues, international research has shown that 0.5 per cent may be more accurate for dry climates.
"As this research has been accepted by the IPCC, the CSIRO - with GRDC support - is currently updating Australia's GHG baseline methodology to use the lower emissions factor from 2024.
"However, with approximately 23 million hectares of land under cropping, Australian growers could still benefit by being able to use accurate, locally derived emissions data for IPCC reporting."
At each trial site, N2O will be measured for the 12 months following harvest to obtain accurate data on the emissions from the decaying crop residues. Crops being studied include wheat, faba beans and canola in NSW and Victoria; maize, sorghum, wheat and faba beans in Queensland; and wheat and canola in WA.
"We have achieved a good spread of representative climate conditions, soil types and crops. Over the two years and five locations, we will gather 32 site-years' worth of data," Professor Rowlings said.
GRDC Sustainable Cropping Systems manager, north, Cristina Martinez said the *new national study was critical in that it aimed to generate representative emissions factors for Australian crop residues alongside region-based data that individual farms could adopt for emissions accounting and reporting.
This research builds on earlier work done by GRDC in partnership with CSIRO for the Australian Grains Baseline and Mitigation Assessment. This 2022 report showed crop residue accounted for 20.4 per cent of all Scope 1 (on-farm) GHG emissions in Australian cropping, compared to fertiliser (15 per cent), lime application or farm operations (11 per cent each). This initial study also concluded that the use of internationally derived emissions factors may be overestimating reportable GHG emissions from the Australian grains sector.
The new national study has a total investment of $8 million, including $4.6 million from GRDC.
This investment is part of the broader GRDC Sustainability Initiative, which recognises that the grains industry cannot have ongoing profitability without healthy soil, water and air; strong rural communities and the trust of grain markets, the finance sector and governments. GRDC is proactively positioning its investment in RD&E to further support growers in achieving sustainability outcomes.
