2023 update: Tecfarm WeedHOG. The Seed Mill with a difference!

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The Tecfarm WeedHOG. Unique ‘Quad Rotor’ design
WeedHOG at work

  Update: February 2023.

 Tecfarm WeedHOG Seed Mills have successfully operated over five seasons. Early years involved shorter “proof of concept” and engineering trials with the last three being full harvests. Concurrently, professionally documented static bed tests were conducted over hundreds of hours

During this current period of finding a licensee/buyer for the design, further valuable experience and confidence has been gained.

 From feedback to date minimal issues were encountered with units in field in the 2022 harvest season. Some observations include: Correct setup of baffles is important to allow good flow of all crop types. This is especially so for green stemmed canola. Rotor bar wear is still surprisingly low. Most owners have rotated impact bars once. Some owners will replace bars this season after three harvests. No problems were seen with factory designed belt drives.

As well as local Australian growers, there is wider interest due to WeedHOG’s observed ability in handling moist crop conditions.

A manufacturing licence or patent purchase is available to a business with demonstrated capacity and expertise in the field of harvest weed control. Please contact Tecfarm for details


The WeedHOG story:

The Tecfarm design teams’ goal was to provide a simple and reliable Harvest Weed Seed Control Mill that is affordable for as many farms as possible. The innovative design stands alone in the field of seed milling, quite different from cage mill based designs, with a unique mode of action via exchange of seeds across a gap between two conjoined circular housings, into the path of opposing high speed impact bars. The WeedHOGs’ engineering is quite simple, but uses complex interactions of air and material. Much research has been devoted to gaining an understanding of the physics involved.

Development: After limited field trials during the 2018 harvest with a unit mounted on a Case 9120 and many hours of bench tests, 2019 harvest trials were conducted in the Western Australian Central Wheatbelt over an extended period, with a pre-production unit operating on a Case 7230 in several crop types. This unit has since been purchased by the farmer who trialled the machine and has operated with no operational or engineering problems. Harvest test results show a big reduction in Annual Ryegrass germination (the main winter crop weed in Southern Australia) using large grow out plots, trays and petri dishes as well as field counts.

2019 was a year of intense work on small variations of the principle involved. The prototype trialled during 2018 harvest was studied at length, refined and given higher capacity. This was achieved by doubling the effective area within the mill, the “Quad Rotor” design and adding additional impact points on each rotor to give greater efficiency.

A consistent direct kill out of the mill was obtained, with mounting evidence through research here and overseas as far back as 1958, indicating that complete destruction is not necessary to render seeds unviable after several months exposure in a field environment.  Observations by Tecfarm personnel verified this phenomenon quite early in testing. It has very big implications for how much energy is required for long term weed control using a mill. As well as Wimmera rye grass, larger weed and volunteer crop seeds have practically a total kill. The low power requirement of the WeedHOG means most harvesters are capable of sufficient power and likely not to require aftermarket ‘remapping/chipping’ of engines to obtain a power boost. 

Tecfarm is also aiming to provide a mill that is suited to the smaller harvesters as soon as practicable. The low power requirement for this design makes it an achievable goal.

It has been observed during R & D that as well as completely destroying a large percentage, the mill damages a high proportion of the remaining seeds. Chaff material tends to be left somewhat intact with a low amount of very fine material. This may be a reason for the units’ observed low power requirement. The Quad Rotor Mill indicated power use at around 40HP (30Kw). Energy is not wasted in making a high proportion of dusty, fine particles.

A major reason for the persistence of annual ryegrass in cropland is its tendency for high levels of dormant seed preventing full germination in any one generation. After passing through this mill the small number of seeds escaping a total kill are observed to have almost all suffered damage and if not subject to infield degradation, appear to have their natural high level of dormancy broken, a trait that is useful to allow spraying out early in the cropping season. Attack by soil borne fungi, microbial activity etc. is also something that seems to happen to damaged seed that has had its’ protective coat compromised. This environmental aspect of the effect of seed mills on seed viability has been seen here at Tecfarm and also observed by US researchers. See: https://aces.illinois.edu/news/harrington-seed-destructor-kills-nearly-100-us-agronomic-weed-seeds-lab-study  It means that quite possibly the need for total destruction of seed is not necessary for good control. This has very practical implications for mill design going forward. Attack by soil fauna and pathogens after even minimal damage to seed coats is very beneficial in giving ‘free’ control.

Features of the WeedHOG:

  • Low capital cost
  • Minimal power requirement
  • Good efficacy on common weed species and volunteer crop seeds
  • Open rotor and housing design reduces green material build up and plugging
  • Unique self-centering rotors eliminate expensive specialised balancing
  • Easy maintenance and low cost rotor bar replacement
  • Impact bars are rotatable to maximise service life
  • Bar sets can be added or removed to suit field/crop conditions and power availability
  • Simple changeover to windrow mode
  • Integral Bolt Traps 

  The future: With engineering and efficacy tests carried out over four Australian harvests and having carried the project as far as practicable with limited resources, Tecfarm is presently seeking a larger company interested in bringing the WeedHOG to full potential.

  Tom Lewis: 0428 611 309. tom@tecfarm.com.au


High capacity Quad Rotor design is unique and simple, with equal discharge from each port
Careful in field testing to establish baseline efficacy figures
Innovative patented design balances milling and material flow with low power requirement
Open day with international researchers

The Tecfarm weed mill is protected under one or more of the following patents:

Provisional patent application 2015903508. International patent application PCT/AU2016/050802. National patent applications USA PCT/AU2016/050802 // Australia No.2016314137. European Union No.P20150710