Study sows the seed for best practice with discs

Author: Tristan Price | Date: 31 May 2013

Key Points

  • South Australian study aims to shed light on disc seeder performance and shape industry practices
  • No pre-emergent herbicide in Australia has on-label recommendations for disc seeders
  • Researchers believe furrow and press wheels could hold the key to developing best practice with disc seeders

A South Australian grains industry research project has sought to shed some light on the benefits and pitfalls of using disc-seeders alongside pre-emergent herbicides and help shape their future use in Australia.

The study, conducted by the University of Adelaide and University of South Australia with support from the Grains Research and Development Corporation (GRDC), aims to refine the industry’s understanding of the use of disc seeders in conjunction with pre-emergent herbicides and inform future on-label advice.

University of Adelaide researcher Sam Kleemann said although growers increasingly recognised the advantages of disc seeders, many pre-emergent herbicides’ on-label advice forbids use alongside disc seeders, and chemical companies often won’t support the use of disc seeders because of a lack of information around the machinery’s impact on crop safety.

“At this point in time, many growers have to use disc seeders at their own risk, and it’s just a function of the fact that they have no other option but do so,” Mr Kleemann said.

“In the last 10 years we’ve seen a lot of advancements in technology associated with disc seeders and this is creating renewed interest, to the point where we’re seeing in South Australia and Victoria around five to 10 per cent uptake, and in parts of NSW even higher again.

“Unfortunately, our predicament with the major weeds we’re chasing is that we’re placing a huge impetus on pre-emergent herbicides. Given the lack of information we have on their behaviour in disc systems, we can’t make any recommendations. Part of this work is trying to develop a greater understanding of how pre-emergent herbicides can more safely be used in conjunction with a disc system.”

Different disc seeder models deliver greatly varying results in crop safety and establishment, and the trial examined five different disc seeders alongside a knife-point and press wheel seeder and in combination with leading pre-emergent herbicides over a five-year period.

While both single disc and knife point seeders placed seeds at around the same depth, the single discs led to higher instances of crop damage, with damage levels varying across the different herbicides used. The study found single disc systems could leave herbicide-exposed soil in the furrow, where knife-points tend to throw treated soil away due to increased soil disturbance.

However, single disc seeders planting at greater depth, and therefore with more soil disturbance, could reduce the risk of crop damage, while planting at shallower levels could increase it. Operating disc seeders at higher speeds could decrease seeding uniformity, resulting in exposure of seeds to herbicide.

Triple discs appeared to have a success rate of wheat establishment comparable with most knife-point systems, and showed much better crop safety than single discs.

“What we’ve found is what’s happening at the front of the machine seems to be far more important to providing crop safety than what’s happening at the rear of the machine,” Mr Kleemann said.

“We’re looking at the function of the closing furrow wheel and the pressing devices and seeing whether they’re dragging herbicide back into the soil furrow.

“All the pre-emergent herbicides we used are non-selective, so they can all cause crop damage whether they’re in a disc or a knife-point system. However, some of the herbicides appear to show better safety with the discs.

“There is potential that perhaps some of these herbicides may be able to get on-label given that we may be able to provide the data and recommendations to do so.”

While the research team cannot make any recommendations to growers at present, their study’s results could help develop standard industry practices for pre-emergent herbicides in future.

To see a video interview with Sam Kleemann, visit


Caption: University of Adelaide researcher Sam Kleemann says a study on using disc seeders with pre-emergent herbicides could shape new industry practices.

For Interviews

Sam Kleemann, Research Officer, University of Adelaide
08 8313 7908


Tristan Price, Porter Novelli
03 9289 9555

GRDC Project Code UA00105, UA0013

Region South