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Agriculture remains a target in the world’s push to reduce greenhouse gas emissions, but local studies show the industry here has ready-to-hand options that should not compromise production or profitability.
In research looking at ways to reduce cropping’s contribution to greenhouse gas emissions, common management practices such as no-till and stubble retention have emerged as ready-made tools. However, the extent to which these practices and other management changes help to reduce carbon dioxide and nitrous oxide emissions will vary across climate zones and soils.
Early results from a GRDC-supported joint CSIRO and University of Western Australia research project show that emissions reductions from practice changes are achievable, but growers will need to know which options are relevant in their region and the possible effects on profitability (Table 1).
|Case study farm||Scenarios that reduce greenhouse gas emissions and ...|
|Decrease profitability||Maintain/increase profitability|
|Dalwallinu and Kellerberrin (Western Australia)||
|Southern Mallee (Victoria)||
The modelling study was part of the Carbon Farming Futures Filling the Research Gap project. It was conducted to predict the trade-offs between yield, farm profitability and greenhouse gas reductions under different management and conditions for representative case-study farms.
The research findings show a range of management practices can potentially reduce greenhouse gas emissions in the GRDC’s western, southern and northern regions.
In the western region, representative case-study farms were defined for the Dalwallinu and Kellerberrin areas. The modelling suggests that greenhouse gas reductions could come mainly from practices that help to increase carbon in the soil, namely:
- retaining stubble;
- using improved legume pastures instead of volunteer weedy pastures in winter fallows;
- opportunistic summer cropping with a short-term green manure legume; and
- regular applications of feedlot manure (if available).
The maximum predicted emissions reduction in these areas, compared to not retaining any stubble, is about 0.8 tonnes of carbon dioxide equivalents (CO2-e) per hectare per year over a 100-year period. For a 1000ha farm, this emissions reduction would offset the emissions produced from burning about 270,000 litres of diesel every year.
The costs of implementing practices to achieve emissions reductions vary. For example, improved pastures in crop rotations could increase farm operating profits by an average of $30/ha/year when averaged across all soil types and typical rotations. By comparison, summer cropping could reduce profits by $30 to $40/ha/year compared to baseline (current) practices (chemical fallows over summer). This is driven by higher costs associated with planting and managing the summer crop and lower yields for the subsequent winter crops.
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