The Livestock Branch of the Department of Primary Industry and Regional Development is working to better understand and develop practical techniques and methods for mitigating the greenhouse gas emissions from the livestock industry in Western Australia (WA). The strategy has two specific aims:
- To lower net emissions from DPIRD’s Katanning Research Station and achieve carbon neutrality on-farm by 2030, and
- To provide and support the application of tested carbon-neutral options for Western Australian broadacre livestock farmers.
As part of the West Australian Government’s commitment to emissions reduction and the sustainable mitigation of climate change, DPIRD identified the Katanning Research Station as:
- a significant greenhouse gas (GHG) emitter; and
- an opportunity to better understand the emissions arising from agriculture, and particularly livestock production.
The Katanning Research Station
The KRS is located 5km east of Katanning on the Nyabing Road in the Great Southern Region of Western Australia. KRS is DPIRD’s primary facility for sheep research. The farm is approximately 2100ha with 1700ha of arable land (suitable for cropping and grazing) and 400ha of non-arable land that is mainly natural vegetation, with saline affected gullies, flats and some areas of tree planting.
Methodology
The KRS research team conducted a carbon footprint assessment of the KRS farm and of its products (grain, wool, sheep liveweight), taking the farm gate as the boundary. The team determined the total emissions from the farm and the product mass and emission intensities of sheep meat, wool and grain. This included upstream emissions, such as emissions from the manufacture of agrichemicals, transport and production of purchased livestock.
We conducted the assessment in accordance with international life cycle assessment (LCA) guidelines, including ISO standard 14067, and with reference to the Livestock Environmental Assessment and Performance small ruminant LCA guidelines. Moreover, we determined livestock and manure emissions using methods consistent with the most recent National Greenhouse Gas Inventory Report (Commonwealth of Australia, 2018).
The impact assessment included Global Warming Potential Values from the Intergovernmental Panel on Climate Change Fifth Assessment Report (AR5), as applied by the Australian NIR. These were 28 for methane and 265 for nitrous oxide. Inventory modelling was conducted using SimaPro 9.0.
Land use at KRS will be modified to meet the modelled scenario of zero net carbon emissions by 2030. The changes will be monitored to validate predictions, and KRS will become a demonstration farm for impact of mitigation methodologies in real-time and practice.
Total emissions
Total emissions for KRS were 2406 and 2553 tonnes of carbon dioxide equivalents (t CO2-e) for 2018 and 2019 respectively, excluding soil and vegetation carbon change. This provided a baseline for KRS of 2480 t CO2-e. Most emissions arose from the sheep flock with lower contributions from cropping.
Product intensity
The carbon footprint (including all on-farm and pre-farm sources) for liveweight gain was 9.5 kg CO2 e.kg LWG 1 in 2018 and 9.9 kg CO2 e.kg LWG in 2019. These values are higher than other published results and are partly explained by lower growth rates for lambs due to experimental constraints.
| Emission intensity by sheep product (kgCO2-e/kg product) | ||
|---|---|---|
| Product | 2018 | 2019 |
| Liveweight gain | 9.5 | 9.9 |
| Greasy wool | 30.2 | 31.6 |
The carbon footprint for wool was higher than previous research from comparable WA systems and these differences were related to overall system productivity, with lower wool yields per breeding ewe in the KRS system. This was partly explained by the fact the sheep flock was modelled by combining the Dorper and Merino flock.
Emission intensities for crops grown at KRS was 0.28 kg CO2 e.kg for oaten hay and 0.78 kg CO2 e.kg for canola were significantly above the emissions intensity referenced by AusLCI for farms in Western Australia. This result was primarily due to the higher ratio of inputs and lower crop yield at KRS in the years assessed.
Opportunities for reducing emissions
The research team at DPIRD identified a range of options for reducing emissions and estimated the impact across the farm operations. These included:
- Reducing total sheep numbers by mating all replacement ewes to Merino sires or by buying in replacement maiden ewes or adult ewes to run a sustainable stocking rate.
- Trialling methane-mitigating feedstuffs including legumes, 3NOP, and Red Asparagopsis.
- Breeding low methane sheep.
- Improving pasture legume content prior to crop to reduce Nitrogen fertiliser and improving weed control.
- Reducing the proportion of crop or changing crop types.
- Prevent soil erosion by wind/water and improving soil characteristics by claying and liming.
- Incorporating carbon into the soil via green and brown manuring and addition of Biochar.
- Changing grazing and pasture species such as alternate legumes, saltbush and browse shrubs and rotational grazing.
The options considered for carbon sequestration utilising vegetation were:
- saltbush systems and fodder shrubs
- windbreaks, shelterbelts and shelter-paddocks and alley farming
- remnant vegetation rehabilitation
- permanent eucalypts and Sandalwood plantations.
Pathways to carbon neutrality
A series of six scenarios were developed for consideration to reach carbon neutrality on KRS. These scenarios were based on different management plans for the sheep flock, combined with different management options for cropping. The residual was a combination of tree planting on non and arable land, saltbush and forage shrubs and the inclusion of methane mitigants such as Asparagopsis. For each scenario, estimated sequestration from soil carbon and tree planting was determined.
| Emissions/ sequestration (t CO2 e/ha/yr) | Livestock emissions | Permanent annual pastures & shrubs | Methane mitigants1 | Green Manuring | New trees non-arable* | Salt land veg | Expected change in soil C % on arable*** | New trees taken from arable** | Residual emissions |
|---|---|---|---|---|---|---|---|---|---|
| Current | 2480 | 0 | 0 | 0 | 0 |
| 0 |
| 2,480 |
| Scenario 1 | 1441 | 72 | 798 | 160 | 36 | 117 | 411 | 912 | - 150 |
| Scenario 2 | 1675 | 72 | 798 | 0 | 36 | 117 | 92 | 1306 | 404 |
| Scenario 3 | 2038 | 72 | 1131 | 0 | 36 | 117 | 141 | 1669 | 384 |
| Scenario 4 | 2178 | 72 | 1131 | 0 | 36 | 117 | 0 | 1809 | 666 |
| Scenario 5 | 1944 | 72 | 1131 | 0 | 36 | 117 | 366 | 1575 | 66 |
| Best bet | 1923 | 94 | 1131 | 0 | 36 | 117 | 389 | 290 | - 1 |
* assume 1.2t CO2 e/ha/yr | ** assume 2.4t CO2 e/ha/yr
****00.73t CO2 e/ha/yr for 5 yrs | ***Soil C (0, 0.05 and 0.1%/yr) 1 90% of flock treated in 2030
The last of these options was the ‘best bet’ option which combined the most likely and practical changes to sheep and cropping management, together with adoption of all of the best mitigations that could be applied to reduce impacts and maximise soil carbon.
Conclusions and recommendations
The KRS is a dedicated research station and doesn’t have the same profitability drivers of a large scale commercial mixed enterprise farm. It also has constraints such as higher labour requirements to supervise trial animals and set aside pasture paddocks for lambing plots. For this reason, the options being tested and considered may be different to those suitable for a commercial property.
All strategies and tactics to achieve a goal must be tempered with the needs of other goals and tactics that are required for an efficient and productive farm. The carbon neutrality goals of KRS will be considered in this light. The positive is that most of these strategies aren’t mutually exclusive and are often complementary, such as revegetation, salinity management, efficient feeding practice and better crop rotations and weed control.
If methane inhibitors are not available in the 2030 timeframe, carbon sequestration through tree plantations becomes more important at KRS to achieve our goals. This indicates that after stock reductions, best practice adoption of legumes and pasture renovations, there would still be a requirement to off-set approximately 1400 tCO2e per year - equating to 580 hectares of permanent tree plantations on productive land.
Significant decreases in GHG can be achieved if there is an opportunity to plant significant areas to carbon sequestration activities such as trees, however, this is not an option for many and has implications for the sustainability of the state sheep flock and export markets.
We have also assumed increases of either 0.05% or 1.0 % in soil carbon per year under new plantings and fodder shrubs, however, these rates have not been achieved in lighter soils and in low rainfall agricultural areas of WA at broadacre scale. If these rates aren’t achieved on KRS it will increase the need for other methods of sequestration. The likelihood of achieving both soil and tree sequestration is made increasingly difficult in a drying climate and with highly variable rainfall to support vegetative growth.
Next steps
The KRS Management Advisory Committee will consider the management changes described in this report to be implemented in tandem with other changes required for other outcomes. An implementation plan with a financial analysis will be developed which will dovetail with the salinity management plan, revegetation plan and water plan.
The opportunity to utilise the Genetic Resource Flock and the Feed Efficiency Facility at KRS for further research and development of methane mitigating feedstuffs is an exciting opportunity for the state and for industry.
Access the full report by click on the document in the side bar (4.5Mb).