P.PSH.1030 - LPP Extending the boundaries of legume adaptation through better soil management
White clover is the most promising perennial legume across the 'high rainfall' permanent pasture zone. Increased persistence of white clover in pasture during drought is associated with increased seed production and seedling recruitment.
| Project start date: | 01 January 2018 |
| Project end date: | 07 November 2023 |
| Publication date: | 22 April 2024 |
| Project status: | Completed |
| Livestock species: | Grain-fed Cattle, Grass-fed Cattle, Sheep, Goat, Lamb |
| Relevant regions: | National |
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Summary
White clover remains the most promising perennial legume species across the ‘high rainfall’ permanent pasture region of south-eastern Australia, where soils are too acidic, shallow and low in fertility to support species such as lucerne. However, white clover lacks the persistence to withstand periodic drought inevitable across most environments. In contrast to lucerne or even strawberry clover, white clover exhibits few mechanisms to conserve water under periods of drought meaning that no management strategy, other than irrigation, will improve its longevity. Rather, white clover persistence in the face of drought is through seed production and seedling recruitment, a trait that has hitherto received little research attention. Further work is recommended to improve reliability of seedling recruitment in white clover, using subterranean clover as a model ideotype, an approach which could extend white clover adaptation well beyond its current niche. Improved soil fertility is a critical component of improved performance under drought to increase its seed production.
Objectives
1. A financial risk analysis detailing the benefits and risks to farm businesses of increasing inputs to soil.
2. Provide producers and advisers with management guidelines to improve the productivity and persistence of pasture legumes in the HRZ which address total feedbase production and feed gap issues.
3. Collation of objective data that defines the potential productivity of key legume species and the mechanisms that increase legume persistence.
4. Objective data defining the impact of changed soil nutrition on herbage mineral concentration, and likely impacts on livestock productivity and health based on comparison with established thresholds.
5. Objective data defining the impact of elevated levels of soil nutrition on symbiotic nitrogen fixation by legumes.
6. Quantified thresholds for soil nutrients that improve legume persistence under moisture stress.
7. Support for post-graduate student projects, in conjunction with a collaborating university, to undertake related research and develop capacity in the field of legume adaptation and nutrition.
Key findings
White clover remains the most promising perennial legume species across the ‘high rainfall’ permanent pasture region of south-eastern Australia, where soils are too acidic, shallow and low in fertility to support species such as lucerne. However, white clover lacks the persistence to withstand periodic drought inevitable across most environments. In contrast to lucerne or even strawberry clover, white clover exhibits few mechanisms to conserve water under periods of drought meaning that no management strategy, other than irrigation, will improve its longevity. Rather, white clover persistence in the face of drought is through seed production and seedling recruitment, a trait that has hitherto received little research attention. Further work is recommended to improve reliability of seedling recruitment in white clover, using subterranean clover as a model ideotype, an approach, which promises to extend white clover adaptation well beyond its current niche. Improved soil fertility is a critical component of improved white clover performance under drought, to increase its productivity and seed production.
Benefits to industry
The project reinforces the benefits of managing soil pH and P-fertility and demonstrates improved legume persistence, increasing the resilience of permanent pastures and, as a consequence, the profitability of livestock production enterprises. The importance of white clover across this region is emphasised, and the use of cultivars such as cv. Haifa that exhibit compatibility with background rhizobia is encouraged. The best way for farmers to increase N inputs to their pasture through biological N-fixation is to increase legume biomass, which is reliably achieved with better soil fertility. By applying these basic principles, farmers will improve the resilience of their pastures under drought and increase the productivity and profitability of their livestock enterprise. An unanticipated benefit to industry was the rediscovery of sainfoin rhizobial inoculum, which was found to be no longer available in Australia. As of 2022 and as a direct result of efforts from this Project in collaboration with the Australian Inoculants Research Group and the South Australian Research and Development Organisation (SARDI), rhizobial strain CC1099 is once again commercially available in Australia.
MLA action
The outputs of the Final report and the key recommendations have been noted by MLA. At this point MLA is unable to progress further research on white clover persistence. There is however, new investment in legumes adapted to low pH soils which overlaps with the findings of this report.
Future research
Seedling recruitment was identified as the key drought-adaptation mechanism employed by white clover. Seedling recruitment is a key drought-avoidance mechanism employed by a range of annual legume species that have proven adaptation to very dry environments and we see advantages in developing a species such as white clover which exhibits a facultative perennial habit, enabling it to use summer rainfall when conditions are favourable. Further research is also warranted to better understand the impact to livestock productivity and meat quality of more nutrient dense forages associated with the increased use of fertilisers.
More information
| Project manager: | Felice Driver |
| Contact email: | reports@mla.com.au |
| Primary researcher: | Dept of Primary Industries NSW |
