Including virtual fencing technology in the weed control toolbox of mixed farming systems has been found to reduce yield losses and herbicide costs

Targeted grazing using near-commercial virtual fencing devices has been found to deliver substantial weed control benefits in crop, pasture and summer fallow settings.

A GRDC investment that tested this weed control technology in 2019–22 – ‘Virtual fencing for better crop integrated weed management’ – has now been analysed for its economic impact to growers.

Adopting project findings was found to be worth $23.50 per hectare to mixed-farm operators, with an additional benefit of $13.34/ha for dual-purpose crop/mixed farm growers.

The challenge

Weed infestations are among the most critical threats to crop productivity. Efforts to innovate weed control strategies recognise that livestock is an important element in the integrated weed management (IWM) toolkit. Grazing is known to reduce or suppress weeds, and in some cases livestock will selectively graze specific weed flowers and seeds.

Weed control using cattle and sheep primarily takes the form of grazing dual-purpose crops, grazing in the summer fallow, grazing in the pasture phase, and potentially grazing for in-crop weed control. Large numbers of livestock already perform these services, including about 65 per cent of the Australian sheep flock.

The emergence of virtual fencing technology has created opportunities to target the grazing to specific zones within paddocks. There are several benefits to this, such as marrying the insights gained from weed mapping technology with a sustainable way to treat zones where the weed burden or seedbank is high.

Controlled spatial grazing also offers the flexibility required to avoid grazing areas of a paddock prone to erosion without losing the opportunity to graze the more stable areas.

However, virtual fencing technology interfaces with animal welfare issues. Its rollout cannot be taken for granted without investment in research that explores the barriers to adoption, efficacy and likely returns to growers.

The response

From 2019 to 2022, GRDC invested in a project that trialled targeted grazing using near-commercial virtual fencing technology. (The technology is permitted for research purposes.) The trial was led by CSIRO in collaboration with Gallagher Australia, an electric fencing company.

Virtual fencing technology is capable of confining livestock within a designated area by using an auditory warning signal when the animals approach the virtual boundary. This is reinforced by an electrical stimulus that trains the animals to react to the warning signal.

Through associative learning, animals learn to avoid the virtual fence by responding to the audio warning alone.

The project was co-led by experts in integrated agricultural systems (Dr Rick Llewellyn) and animal behaviour (Dr Caroline Lee). It used GPS–enabled, solar-powered neckband devices (eShepherd^®) to train cattle. The device emits a mild electrical pulse to animals that ignore the audio cue and continue to move towards the virtual fence.

This experimental set up required a satellite base station, cloud-based data storage and an app. That technology is being commercialised by a Melbourne-based agricultural technology company, Agersens, using patents developed at CSIRO. The team has also started adapting this technology for sheep using an eartag device instead of a neckband.

Five trials were conducted on mixed farms across South Australia as part of the three-year project. The primary aim was to increase grazing pressure on weed populations, particularly ryegrass, to reduce weed seed production within problematic paddock zones.

The impact

Virtual fencing was found to offer promising weed control opportunities with consequent contributions to improved farm productivity and yields. For example, virtual fencing more than halved the amount of ryegrass seed heads compared with paddock-grazed controls, without affecting the live weight of cattle.

In analysing the likely economic cost-benefits to growers, conservative assumptions were made given future uncertainties related to the commercialisation process. Included is the requirement for changes to regulatory restrictions on the use of electronic shock on sheep in those jurisdictions that prohibit the technology beyond research.

The main benefits were attributed to a 10 per cent reduction in the use of herbicides with a 10 per cent reduction in weed-related yield losses. An additional five per cent reduction in yield loss was also observed with dual-purpose crops.

This translates to an extra $23.50/ha for mixed-farm systems and an additional $13.34/ha for dual-purpose crop mixed farms.

In all, $1.53 million was invested in this research, with GRDC contributing $0.71 million. Under conservative assumptions, the present value of benefits was estimated at $14.99 million, with $7.02 million attributable to GRDC.

This amounts to a benefit-cost ratio of 9.87. The economic analysis was performed by ACIL Allen in July 2024

More information: view GRDC’s ‘Delivering impact’ case studies.