P.PSH.1029 - LPP Increasing livestock production by integrating tropical pastures into farming systems
Tropical pastures have potential benefits in temperate regions of SE Australia under current and projected climate changes. Tropical pastures can persist and increase profitability, especially in regions where lucerne is currently grown.
| Project start date: | 15 April 2019 |
| Project end date: | 15 August 2022 |
| Publication date: | 24 June 2024 |
| Project status: | Completed |
| Livestock species: | Grass-fed Cattle, Sheep, Goat, Lamb |
| Relevant regions: | Southern Australia, Eastern Australia |
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Summary
The projected climate change for southern Australia is predicted to shorten the growing season of temperate species with likely increases to the summer-autumn feed gap. Tropical perennial grasses are summer growing, drought tolerant, and offer the potential to contribute to summer and autumn forage in both current and future climate scenarios. This multidisciplinary project used a combination of modelling, field studies and social research to (i) investigate the potential of tropical pastures in Southeast (SE) Australia, and (ii) improve tropical pasture productivity and sustainability in northern NSW by better understanding the dynamics of tropical grass-legumes mixes and strategies for more effective pasture utilisation.
The project demonstrated tropical perennial pastures have potential benefits in SE Australia both under current and projected climates. Species evaluation confirmed that they can persist in environments previously considered marginal. Modelling indicated tropical pastures can increase profitability of current temperate-based grazing systems in most locations tested, although the result was variable, especially where lucerne is productively grown. Some keys to successful establishment were quantified and producer enablers and constraints to trialling these pastures were identified. The opportunity and management of temperate annual, lucerne, desmanthus and leucaena as companion legumes in tropical grass pastures were refined. Tropical pastures were also successfully ensiled.
Objectives
1. Define the area suitable for tropical grass species and the fit in the farming system under current and future climate scenarios.
2. Determine the requirements for successful establishment.
3. Develop regionally relevant agronomy packages (e.g., weed control and maintaining high feed quality).
4. Enhance companion legumes and refine their management.
5. Determine the whole-farm and system benefits from introducing these species.
Key findings
• Potential distribution of tropical perennial grasses accounting for climate, soil type and land use is larger than that currently sown and will generally increase with projected climate scenarios in SE Australia.
• Modelling indicated tropical perennial grass pastures could provide feed during the late summer-early autumn period when the traditional temperate-based pastures are inactive. Incorporating tropical pastures increased profitability in most locations but this was less likely to occur in areas with milder conditions where lucerne (Medicago sativa) was productive. Profitability declined and gross margin variability increased in recent years, suggesting that while incorporating a tropical pasture can improve profitability, further adaptations will be required if climate trends continue.
• Under conditions with increasing temperatures and more variable rainfall, the role of tropical pastures is likely to increase.
• Tropical grasses that performed well at sites in central and southern NSW after 3–4 years were digit grass (Digitaria eriantha) cv. Premier and Makarikari grass (Panicum coloratum var. makarikariense; Bambatsi panic) cv. Bambatsi. Other grasses that performed well at some sites were Rhodes grass (Chloris gayana), kikuyu (Cenchrus clandestinus syn. Pennisetum clandestinum) and panic grass (Megathyrsus maximus var. maximus).
• Recommended minimum temperatures for sowing tropical species have been determined. Minimum spring temperatures for sowing range from 17oC (Rhodes grass) to 22oC (paspalum; Paspalum dilatatum).
• In central west NSW, seedling emergence was highest in spring and autumn. Plant survival (9–14 months after sowing) was highest for grasses sown in spring with high stored soil moisture levels. The effect of high soil moisture was still evident 18 months after spring sowing.
• Enablers and constraints to trialing tropical perennial grasses have been identified. This information is important for development of an effective extension.
Benefits to industry
Research has shown that tropical pastures have potential in SE Australia (and specifically NSW), providing a practical solution for producers to maintain green feed during summer-autumn in current and projected climates. Maintaining a productive persistent companion legume can reduce input costs also increase pasture growth and quality, and therefore livestock production. The reported antimethanogenic properties of desmanthus and leucaena is an additional benefit for red meat producers.
MLA action
Feedbase team has been dialogue with the research team to further develop extension materials and support a network of demonstration sites for producers wanting to trial tropical pastures, and to integrate selected elements of further research. Budget constraints mean this is on-hold for now.
Future research
1. Increasing livestock production by integrating tropical pastures into farming systems II. There is increasing interest in tropical pastures in central and southern NSW. A phase II of our current project would be a collaborative RD&E program.
2. Sequestering carbon and reducing methane emissions with tropical legumes at southern latitudes. Quantify species/characteristics which offer multiple benefits for production systems; long-term C sequestration, maintain or improve animal performance; reduce methane emissions under variable climatic conditions. conduct component research to address gaps in our knowledge (e.g., nitrogen fixation potential of tropical grass-legume mixes), and extension to support producers trialing and adopting tropical pasture mixes in their grazing systems. This project links with other projects in the MLA CN30 program.
More information
| Project manager: | Cameron Allan |
| Contact email: | reports@mla.com.au |
| Primary researcher: | Dept of Primary Industries NSW |
