The Derwent Catchment Project – Forage Shrub Trial
| Project start date: | 30 July 2019 |
| Project end date: | 15 June 2023 |
| Project status: | In progress |
| Livestock species: | Grass-fed Cattle, Sheep, Lamb |
| Relevant regions: | Tasmania |
| Site location: | Tasmania |
Summary
The Derwent Catchment has a semi-arid climate and suffers from episodic droughts which are likely to increase with a changing climate. The predominant land use in the region is dryland grazing which is reliant on pastures and runs. The pastures are under increasing pressure and are unreliable in times of drought. Cleared North-facing slopes have been recognised as a particularly fragile component of dryland enterprises in the Derwent Catchment, as they are difficult to incorporate into grazing system without significant environmental impacts.
Research has identified that forage shrubs are an
ideal management option to improve grazing productivity of North-facing slopes in the Derwent Catchment. This Producer Demonstration Site will apply learnings from the mainland states and design, implement and evaluate the productivity benefits of forage shrubs in Tasmanian grazing systems and determine the profitability of their establishment.
Objectives
By the 1st of March 2023 the project will:
1. Have demonstrated and assessed the potential of perennial forage shrubs – over a minimum of two grazing seasons - to contribute to useful fodder to address the Winter feed gap on marginal land (North-facing slopes) in Tasmania by:
a. Increasing or maintaining liveweight of lambs (pre and post grazing weight), and
b. Increasing stocking rate (DSE) without associated environmental impact on ground cover
c. Increasing inner row pasture ground cover (kg/DM/ha)
d. Increasing available forage (biomass measured in kg/DM/ha) nutritional value comparison to pasture will be included
2. Have conducted a costed proof of concept for the establishment of forage shrubs on North-facing slopes comparing planting seedlings to direct seeding methods across 3 demonstration sites.
3. Have facilitated a peer learning group of core producers who drive demonstration site design, establishment and monitoring. This peer learning approach will be used to produce a proof of concept to increase uptake by the 11 core producers to incorporate the use of perennial forage shrubs on marginal areas of their grazing systems. This will be measured by evaluation of pre and post knowledge, capacity, skills and confidence of producers.
4. Have conduct workshops and field days and produce a range of supporting resources to showcase the demonstration site results to encourage adoption of key practices by 44 observer producers. Survey of 44 producers will be undertaken to assess changes to the likelihood of adoption.
Progress
The Derwent Catchment Project is undertaking a perennial forage shrub trial on marginal, erosion prone north-facing slopes in the Central Highlands of Tasmania. The trial planted tubestock and direct drilled Mediterranean saltbush (Atriplex halimus) at three 5 ha sites with a 5-ha control at each site. The purpose of the trial is to determine if establishment is possible, what is the cost-benefit of any production and environmental outcomes. The trial has successfully established saltbush at one of the three sites. The project has identified the suitability parameters required for shrub establishment and persistence on north facing slopes; sites are best suited to very sandy soils away from any native bush or remnant vegetation. Site maintenance including fence checks and weed control have been undertaken. We look forward to comparing the cost/benefit of the remaining site with 2 other similar saltbush sites that have been established parallel to this project under the Derwent Pasture Network funded by NRM South through the Australian Government’s National Landcare Program. The Derwent Catchment Project has continued to communicate about the saltbush trials through social media, newsletters and presentations to producer groups and the State Government’s Agricultural department.
