Seed destructor a model of R&D teamwork
GroundCover™ Issue: 124 | Author: Rebecca Jennings
A 20-year labour of love by a WA grower; an innovation further refined by a SA university, with funding from Australian growers through the GRDC; and an SA company throwing all its efforts into manufacturing the technology in Australia. This is the story to date as the Integrated Harrington Seed Destructor – an extraordinary new tool for tackling herbicide resistance – heads to market
Most growers will know the story of Ray Harrington, the innovative Western Australian grower who took matters into his own hands to find a solution to herbicide resistance. Over two decades, his Harrington Seed Destructor (HSD) evolved to become a tow-behind weed-seed-smashing harvest tool. With funding from the GRDC and the Australian Herbicide Resistance Initiative (AHRI), the HSD was eventually commercialised by South Australian-based engineering firm de Bruin Engineering.
However, there is another less well-known side to the story – the six years of complementary research conducted at the University of South Australia’s (UniSA) Agricultural Machinery Research and Design Centre (AMRDC).
The centre is well known for tillage research, but in 2010 the GRDC tasked it with engineering a solution for the ‘pointy end’ of the season, in the form of an integrated (into a header) weed-seed destructor.
When the first iHSD was manufactured in de Bruin’s Mount Gambier plant in May this year, it was the culmination of an R&D journey that crossed state lines, presented plenty of engineering challenges, and delivered a research solution to one of the biggest problems facing growers: herbicide-resistant weeds.
The GRDC project was an AMRDC team effort headed by UniSA Professor John Fielke, led by research engineer Dr Chris Saunders and the research focus of Dr Nick Berry, who began on the project as a PhD student. Senior research engineer Andrew Burge contributed to the electronics, while technical assistant Dean Thiele was integral to building prototypes.
Weed researcher Dr Michael Walsh also played an integral role through his research on the seed-destruction rates of many types of mills, while the late Dr Graeme Quick provided his expertise as a harvester consultant.
They set out to understand the fundamentals of weed-seed devitalisation and to engineer, from the ground up, a system that could bolt on to a harvester and be driven from the machine’s own engine, for a one-pass harvest-weed-seed ‘terminator’.
They developed technology to deliver ‘mechanical impact trauma’ to the seed – that is, to smash seeds in a mill as chaff exits the harvester.
The efficiency of the seed destruction depends on how much impact is applied, so Dr Berry’s PhD research drilled into the basics of material impact to examine the optimal means of ‘devitalising’ weed seeds (taking into account the cushioning effect of the chaff). He ran germination trials and complex computer models to test the suitability of different options.
After two years, a concept was born and put to the test at Richard Konzag’s Mallala, SA, farm in 2012. This prototype was integrated into UniSA’s research header – a Case IH 9120. Three forward speeds and three cutting heights were used to assess material flow rates and test mill capacity. While successful, it was only manufactured as a ‘proof-of-concept’ model – more work was needed.
Following this short testing period it was back to the computer model and workshop to refine and improve the technology. As the team trialled more than 100 computer-simulated designs, researchers tweaked the internal mill design to achieve more seed destruction with less power.
A second prototype was rolled out for the 2013 harvest, while the first, upgraded, prototype headed west, where Ray Harrington used it for a full season of testing.
After further design refinements and testing to reduce power requirements and lessen the load on the harvester engine, four more prototypes were put through their paces by growers in SA and WA during 2014. Meanwhile, Ray took on the second prototype and UniSA trialled the research unit under different harvest environments in SA, Victoria and NSW.
While the original HSD incorporated a cage mill, as used in the mining sector, Dr Saunders says the UniSA research team developed bespoke rotor-stator milling technology.
“The integrated system consisted of two hydraulically driven mills that are mounted to the rear of the harvester just below the sieves, a dedicated hydraulic drive system, reservoir and oil cooler, with a full-featured in-cab control, display and monitoring system,” he says. “We refined the design to save on power while maintaining efficacy. Based on testing by AHRI, the mills can devitalise 93 to 98 per cent of the weed seeds that enter them.”
During prototype development the researchers also refined the design for ease of manufacture, assembly and installation onto the harvester, reducing both its complexity and weight. After the second successful year of grower-operated units, the integrated prototype was ready for commercialisation.
Reflecting on the past six years, Dr Saunders is enthusiastic about how engineering research was able to design, develop and prove successful a header-integrated option for non-chemical control of weed seeds at harvest time.
“AMRDC has developed engineering solutions for growers over the past 20 years – we’ve done a lot of work in tillage – but with this project we have developed the fundamental design for a harvest-time seed destructor that can devitalise weed seeds in a one-pass process.”
When asked if total weed seed devitalisation could ever be an option, he points out the realities of farming and engineering: “While 100 per cent devitalisation is technically possible, achieving this would place a huge load on the harvester engine – the power required to achieve that last few per cent efficacy requires an exponential increase in power.”
This is where Jud Wheatley, managing director of de Bruin Engineering (the firm selected by the GRDC and UniSA to manufacture the integrated design), took over the prototype – and the Integrated Harrington Seed Destructure (iHSD) story.
“Turning a research prototype into a manufacturing reality has required some tweaking,” Mr Wheatley says.
“For example, we made efficiency gains by taking proven industrial electrical componentry used in the tow-behind HSD and dropping it into the integrated model. A new compact, dust-resistant hydraulic cooling system was added, and the size of the mills’ motors were increased so they operate smoothly under heavy load and have additional torque capacity when required.”
The units weigh 450 kilograms and measure 1500 millimetres by 800mm. They integrate into the back of the header, behind the sieves, and have a normal running load of about 100 horsepower.
Research has not ended with the commercial unit either. The iHSD control system logs integrated information from the iHSD and the header’s CAN bus system, which will provide performance data that will improve its efficiency and efficacy over time.
Mr Wheatley says the largest manufacturing challenge has been adapting the iHSD for every make and model of header. For the first season de Bruin Engineering developed units to fit four Case IH models (8120, 8230, 9120, 9230) and three New Holland models (9090, CR9.90, CR10.90). However, an ongoing development effort will see the product fitted to additional header makes and models each year, to increase the availability of iHSD over time.
The first manufacturing allocation was quickly filled by WA growers, but de Bruin is taking orders through Australian distributor McIntosh and Son for next season’s expanded production. With a production of about 40 units for 2017, iHSDs will be manufactured on a monthly basis from January 2017. “The units will be allocated on a first-come, first-served basis, with priority given to those who have registered their interest via the iHSD website,” he says.
Of course, the mill is not only damaging the weed seeds. The throughput of cereal seeds might see growers with livestock in their farming system steer away from annual use of the iHSD. However, for continuous-cropping systems the technology can reduce the summer ‘green bridge’ without the need for chaff carts or burning. As with other harvest-weed-seed management strategies, not all weed seeds are captured at harvest so an integrated weed management approach will still be required.
“The iHSD is an important tool in an arsenal in the fight against herbicide resistance. When a seed enters the iHSD there’s around five per cent chance it will come out viable because there is no effective resistance to destruction,” Mr Wheatley says.
“This technology enables a single-pass harvest without the need for chaff carts, windrowing or burning, so it’s a great option for continuous cropping as it prevents the vast majority of weed seeds from entering the seedbank, and it immediately returns organic residue back to the soil that would otherwise have been lost to burning. Although the iHSD won’t eliminate the need for chemical control and organic replacements, it will enable growers to be more selective in the chemicals they apply, which ultimately leads to lower production costs.
“We really believe in this product – it’s a game-changer for agriculture in Australia,” says Mr Wheatley about de Bruin Engineering’s focus on the iHSD.
“It’s an Australian invention, funded by Australian growers and government, developed by an Australian university, 100 per cent manufactured in Australia by an Australian company.”
With herbicide resistance in weeds a growing global problem, the iHSD also has the potential to be a great Australian success story. There has already been strong interest from outside Australia, with about half of the enquiries through the iHSD website coming from overseas.
08 8721 3888,
Growers can register their iHSD interest
‘Integrated Weed Control & HSD’ – vide
(Ground Cover TV with the Uni SA prototypes)
See also ‘Northern harvest weed-seed trials’