Grains: How to reduce emissions

Background

NSW DPI, in collaboration with CSIRO and Lifecycles Pty Ltd, was funded by the Grains Research and Development Corporation (GRDC) to benchmark the environmental impacts of producing key grain crops throughout Australia, and to assess the potential for management changes to wheat production to provide climate change mitigation.

Project outputs provide information for growers, agronomists and policy makers to understand the impacts of production, the source of impacts and how management change may minimise the emissions of greenhouse gases from the systems.

The project assessed the impacts of producing the two key cereal/oilseed crops and key legume crop for each GRDC agro-ecological zone (AEZ) and modelled specific mitigation strategies, outlined below.

Table 1: Primary cereal/oilseed crops and primary legumes for each agro-ecological zone (AEZ)

AEZ	Cereal/oilseed 1	Cereal/oilseed 2	Legume
NSW Central Regional Summary	Wheat	Barley	Field peas
NSW NE Qld SE Regional Summary	Wheat	Sorghum	Chickpeas
NSW NW Qld SW Regional Summary	Wheat	Barley	Chickpeas
NSW Vic Slopes Regional Summary	Wheat	Canola	Lupins
Qld Central Regional Summary	Wheat	Sorghum	Chickpeas
SA Mid North Lower Eyre Peninsula Regional Summary	Wheat	Canola	Lentils
SA Vic Bordertown Wimmera Regional Summary	Wheat	Barley	Lentils
SA Vic Mallee Regional Summary	Wheat	Barley	Lupins
Tasmania Regional Summary	Wheat	Barley	N/A
Vic High Rainfall Regional Summary	Wheat	Canola	Faba beans
WA Central Regional Summary	Wheat	Canola	Lupins
WA Eastern Regional Summary	Wheat	N/A	Lupins
WA Mallee Sandplain Regional Summary	Wheat	Canola	Field peas
WA Northern Regional Summary	Wheat	Canola	Lupins

Mitigation Strategies

Potential climate mitigation strategies modelled for the National Grains Life Cycle Assessment project include;

Strategy	Explanation
Sustainable intensification	This mitigation strategy assessed the climate impacts of increasing N fertiliser inputs so wheat yields reached the water-limited yield potential (WLYP). The WLYP was taken from the Yield Gap Australia project (www.yieldgapaustralia.com.au), the model assumed additional N was applied as urea and assumed the partial factor productivity of applied N was 55 kg wheat per kg N applied
Increasing lime inputs	This strategy assumed that the frequency of lime applications doubled to that of average regional practice. It was only modelled for regions that were dominated by acid soils.
Implementing variable rate technology (VRT) for fertiliser	This strategy assumed that the implementation of VRT reduced fertiliser inputs for a wheat crop by 20% compared to the baseline system.
Adding legumes in rotation	Legumes are regularly incorporated into cropping rotations so this strategy tested the assumption that replacing a wheat crop with a legume crop any benefiting from the additional N fixed by the legume offset the impacts of using synthetic fertiliser in wheat system

More specific information is available in the results from each agro-ecological zone (AEZ) accessed by clicking the links in the table above.

Data sources

Many data sources were used to assess the impacts of crop production. Face-to-face interviews were held with regional experts such as agronomists, consultants and researchers in each AEZ. They provided data such as crop yields, rate and timing of farm chemical applications, rate and frequency of soil amendments, and fertiliser inputs. Other data sources used were statistics from the Australian Bureau of Statistics and publically available research databases. Data from all sources were compared and data selected to assess the impacts of crop production for “common practice” throughout the zone.