Drought resilient pasture systems

WHY THIS PROJECT IS NEEDED

Central and southern NSW were once dominated by deep-rooted, perennial-based grassy woodlands. Since European settlement, landscapes have transformed to highly annualised systems, which has had a major impact on farm production and ecosystem health, function, and resilience, especially during times of drought.

This project aims to use the latest research on species and management to increase the use of perennial pasture species within farming landscapes and increase resilience in dry seasons.

Drought resilient pastures contain a high proportion of productive perennial grasses, especially when accompanied by well adapted legumes inoculated with effective rhizobia. The establishment or enhancement of these pastures provides permanent habitat for above and below-ground biodiversity and protects soil from erosion and structural loss, while also buffering against high temperatures and rapid desiccation.

Drought resilient pastures also maintain higher organic matter and soil fertility levels, which can better support ecosystem function, particularly during times of drought. They can also suppress weeds, cycle nutrients, provide higher and more stable source of nutrition to stock and wildlife.

Drought resilient pastures can also aid recovery following drought, thereby increasing the profitability and stability of farm systems. The deeper roots of perennial pastures also increase carbon sequestration and water utilisation, reducing salinity, acidity and nutrient loss, while their ability to extract water from deeper in the profile can extend the growing season, increasing resilience in dry seasons.

Recent research also highlights their potential to reduce livestock methane emissions. As such, well adapted, more drought resilient pastures have the potential to contribute to Australia’s goals for both net zero carbon emissions by 2050 and an Agricultural Industry achieving $100bn in farm gate output by 2030.

Project focus

The project specifically aims to help farmers build knowledge, skills and confidence to improve their pasture base, either by using practices to enhance favourable species already present, or by establishing new pastures. This will help address feed base management and farmer concerns around its impact on drought resilience.

A number of demonstration sites have been established across the mid to high rainfall zones of central and southern NSW to showcase modern pasture species combinations and management practices known to build greater resilience into landscapes.

In the Riverine Plains, demonstration sites have been established at Barooga and Savernake to identify the best pasture practices for local conditions.

• The site at Barooga aims to demonstrate the benefits of rotationally grazing lucerne for improving pasture persistence, pasture quality and animal production.
• The Savernake site aims to demonstrate the impact of lucerne seeding rate and variety on pasture persistence and quality.

Measurements are being collected from both sites to quantify soil nutrition, establishment rates, species frequency and composition, biomass production and pasture quality. Lamb growth rates will be measured at the Barooga site to demonstrate the impact of rotational vs set stock grazing practices on animal production.

Outputs from the demonstration sites will be modelled using decision support tools to explore environmental, production and economic impacts of practice changes on farm.

Field days and workshops, case studies, videos, publications and on-farm consultations will help communicate key learnings and outcomes from the project.

Project outcomes

Drought resilient pasture sites at Savernake and Barooga

During 2023, two lucerne demonstration sites were established at Savernake and Barooga as part of the Changing landscapes with drought resilient pastures project.

Savernake

The Savernake site is hosted by Chantelle and Christine Gorman and aims to demonstrate the impact of lucerne seeding rate and variety on pasture performance and persistence.

The paddock was sown in late May 2023 with a winter active lucerne (cv SARDI 7s2) at 5 kg/ ha, a mid-maturing Brachycalycinum clover (cv Mintaro) at 3 kg/ha, and an early-mid-maturing Yanninicum clover (cv Monti) at 3 kg/ha as the farmer control. Two comparison treatments were sown in the middle of the paddock; a ‘SARDI 7s2 Heavy’ treatment comprising 9 kg/ha SARDI 7s2, 3kg/ha Mintaro and 3 kg/ha Monti, and a ‘SARDI Combo’ treatment comprising a 5 kg/ha combination of SARDI 7s2 and SARDI Grazer (a winter active, grazing tolerant lucerne) with 3kg/ ha Mintaro and 3 kg/ha Monti.

The crops established well and by September total pasture biomass was greater in the SARDI 7s2 Heavy treatment (1800 kg DM/ha) than in the farmer control (1600 kg DM/ha). Lucerne composition was greater the heavier sown treatment, likely contributing to the overall greater biomass. Sub-clover biomass was slightly greater in the farmer control (1000 kg DM/ha) compared to SARDI 7s2 Heavy (900 kg DM/ha), probably due to the lower lucerne competition in this treatment.

The pasture was first grazed in mid-late January 2024 by 1200 ewes, with visual differences between lucerne in the treatments (the lucerne in the farmer control was shorter and a lighter colour than the SARDI 7s2 Heavy and SARDI Combo treatments). The site received its first irrigation (20mm) on 5 February 2024.

Barooga

The Barooga site is hosted by John and Sarah Bruce and aims to demonstrate the benefits of rotational grazing lucerne and how a rest period can improve pasture persistence, quality and animal production. The site consists of two 10 ha dryland paddocks sown to 9 kg/ha L70 lucerne and 6 kg/ha Zulumax arrowleaf clover in late May 2023. Two irrigated 20 ha paddocks (centre pivot) sown to lucerne in 2019 were also included as part of the demonstration.

The two dryland paddocks established well and by early October were ready for grazing, with a biomass of around 2000 kg DM/ha, compared to 3000-4000 kg DM/ha in the established lucerne stands. The pasture grew well over the grazing period, exceeding consumption, so that pasture biomass increased during grazing.
During early October 2023, 525 wether lambs were weighed and drafted into two mobs, with one mob rotating between the two dryland paddocks and one of the centre pivot paddocks, while the other mob was set-stocked on the other centre pivot paddock. In late October the lambs were weighed, with results in Table 1.

Table 1 Barooga grazing demonstration site wether lamb weights

Treatment 1: Rotationally grazed on dryland lucerne/clover & irrigated established lucerne stand. Treatment 2: Set stocked on established irrigated lucerne stand.

Acknowledgements

Thanks to the Gorman and Bruce families. Further results will be published in Research for the Riverine Plains, 2024.

Webinar

As part of this project, a webinar covering pasture persistence and performance was held with Sophie Hanna from Riverine Plains, John Bruce from Barooga, Richard Hayes from NSW DPI and Susan Robertson from Charles Sturt University.

A recording of the webinar is available to view below.

This project is supported by the Southern NSW Drought and Innovation Hub, through funding from the Australian Government's Future Drought Fund.

Full project title: Creating landscape-scale change through drought resilient pasture systems.