The Harrington Seed Destructor (HSD) is on the verge of taking the step that most grain growers would like to see. The majority of Australian grain growers who have seen the HSD are very positive about the concept of destroying weed seeds as they exit the harvester. It seems crazy that we would spread the weed seeds back over the field (so we have something to spray next year!). However, many growers have commented that they are reluctant to tow such a machine behind their harvester.
Agricultural engineers from the University of South Australia in collaboration with AHRI, are taking the Harrington Seed Destructor to the next level. They have built the first prototype of a mill that is mounted within the rear of the harvester to destroy weed seeds as they exit in the chaff fraction. This technology is still in the prototype stage, and the first indications are very exciting.
This new version of the HSD is known as the Integrated Weed Destructor (IWD). It is a modification of the original HSD invented by Ray Harrington, grain grower from Darkan, Western Australia. The HSD has proven efficacy, consistently destroying greater than 95% of the seeds of a range of weed species that enter the mill (see paper below).
The IWD mill is a slightly different design to that which features in the HSD. As such, the IWD will be put through its paces this year by Dr. Michael Walsh (AHRI) to determine the kill rate of a range of weed species. Initial testing and modelling suggests that the IWD mill should be as effective as the HSD mill at destroying weed seeds.
The video below shows two IWD mills mounted to a class nine harvester (hydraulically driven) operating at approximately class eight capacity (up to 40 t wheat harvested /hour). Chaff from the main sieve is directed into the mills via a simple chute. It requires approximately 80 to 100hp to drive the mills, which is why the harvester operates below maximum capacity.
This is clearly an exciting development for the future of weed seed crushing, however keep in mind that the HSD is a proven performer and is currently commercially available. De Bruin engineering (see link below), the manufacturers of the HSD, will continue to build a small number of tow-behind HSD’s to meet current market demand whilst testing and development of the IWD occurs over the next few years.
It is widely acknowledged by many in the agricultural industry that weed seed destruction at harvest is necessary as a key non-herbicide weed control tool to manage herbicide resistant weeds. GRDC, AHRI, University of South Australia and De Bruin engineering are all committed to delivering this world leading technology to Australian grain growers. There are clearly opportunities to develop this technology in other countries in the future.
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