Pasture seed industry collaborates to improve harvesting techniques


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Innovative design modifications to a Horwood Bagshaw clover seed harvester is the first step to bringing subterranean clover and annual medic harvesting methods rapidly into the 21st Century.

The AgriFutures Australia-funded research brings together a diverse team from the University of Western Australia (UWA) with expertise in agricultural engineering, pasture agronomy and plant breeding, to develop a social, environmental and economical harvesting approach for Australian subterranean clover and annual medic growers. Ultimately, the UWA researchers aim to improve on 60-year-old harvesters that are labour intensive and travel at just a few kilometres per hour.

Twelve months into the project the team have completed phase one, a series of on-farm consultations, workshops and surveys in WA, SA and NSW to capture the collective knowledge of this unique industry.  The team have now embarked on phase two, benchmarking harvester performance on seed growers’ crops in WA and SA.

AgriFutures Australia Manager, Research, Annelies McGaw said enhancing performance and paving the way for the industry’s first efficiency gains in decades was top of mind for AgriFutures Australia’s Pasture Seeds Program .

“Current harvest practices for sub clover consist of four stages, including removal of excess dry plant residue, several machinery passes to bring burrs to the surface; one to three passes of vacuum harvesting; and post-harvest treatment to reduce wind erosion,” said Ms McGaw.

“This benchmarking is vital for gaining data on harvesting efficiency and soil loss using current technology, so researchers can compare performance of new designs – potentially incorporating technologies from other industries such as peanuts and potatoes.”

The project, led by UWA’s Dr Phil Nichols and Professor William Erskine, with Engineering support from Dr Andrew Guzzomi and pasture agronomy support from Dr Megan Ryan and Dr Kevin Foster, adopts a two-pronged approach:

  • Engineering – to assess modifications to current machinery and propose new designs
  • Agronomic and soil management – to reduce soil erosion prior to, during and following seed harvesting.

Dr Nichols said the main focus was on subterranean clover, as it has the largest seed industry, but many principles will also apply to annual medics.

“Inspection of peanut harvesting in Kingaroy, Queensland suggests similar machinery could be developed for sub clover seed harvesting, but would require changes to pre-harvest agronomy,” he said.

In addition to the consultation and workshops PhD research student, Wesley Moss, has conducted a grower survey and is taking a close look at design options.

Mr Moss said studies underway were designed to better understand the burr attachment characteristics of sub clover plants and their changes with plant senescence.

“A terminal velocity machine has also been built to examine the aerodynamic properties of burrs and seeds to inform the design of more efficient harvesting machinery,” said Mr Moss.

Fourth generation sub clover grower Andrew Shepherd and his family have been growing sub clover for more than 100 years.

According to Mr Shepherd in the early days sub clover was harvested by raking up all the material and feeding it through a stationary threshing machine by pitch fork. The Shepherds were still using a similar principle to this up until the early 80’s, when they switched to using the Horwood Bagshaw clover seed harvesters.

“We’re still using the conventional Horwood Bagshaw harvesters. Each winter we essentially need to rebuild the machines with custom fabricated parts,” said Mr Shepherd.

“Sub clover is an important pasture in farming systems and we’ve seen a resurgence in the last five years. We need an efficient, reliable and viable solution to sustain the future of the industry. I have been working with the UWA research to help document the history of the industry, as well as the on-farm benchmarking to see how successful and economical the existing machines are and potential of harvest field gains,” said Mr Shepherd. “Essentially we want to understand if these machines are reaching their potential? Is their scope to modify the machines now?”

To receive updates on this project please register for the Pasture Seeds Program Industry Update at



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