Growers’ experiences in using the newer harvest weed seed control (HWSC) techniques of chaff lining and chaff tramlining, as well as strategies for harvesting low biomass crops, are shared in two new Grains Research and Development Corporation (GRDC) publications.
GRDC grower relations manager – west, Jo Wheeler, said the two grower case study booklets were produced after these issues were raised as priorities by Western Australian GRDC Regional Cropping Solutions Network (RCSN) groups.
“Specifically, the Kwinana East RCSN has been interested in investigating HWSC techniques in Western Australia’s dry, eastern grainbelt conditions, where there are often smaller crop residues,” Ms Wheeler said.
“The Esperance RCSN wanted to assess the HWSC methods of chaff lining and chaff tramlining, which are attracting increasing interest from growers.”
Chaff lining involves making a narrow windrow of chaff only in the middle of the harvester, with weed seeds being concentrated in that zone and straw spread as usual.
In many cases, the chaff line is not burned, but is left on the soil surface for weed seeds to rot. Any plants that do emerge have to compete with each other in a narrow row, leaving the remainder of the subsequent crop area relatively clean.
The harvester needs to follow the same tracks each year to make sure the chaff line is dropped on the old one, but this can be done even without using a full Controlled Traffic Farming (CTF) system.
Chaff tramlining is where the chaff is concentrated onto permanent tramlines and is best suited to CTF systems. One of the tools used to achieve chaff tramlining is a ‘chaff deck’ – two small conveyor belts that take the chaff from the sieves and place it onto the tramlines.
Consultant Peter Newman was part of a Planfarm team that produced the GRDC publications ‘Investigating the harvest weed seed control tools chaff lining and chaff tramlining (chaff deck) in the Esperance area’ and ‘Investigating harvest weed seed control tools in low biomass crops in the Kwinana East Zone’.
Mr Newman, who is also the western region extension agronomist for the Australian Herbicide Resistance Initiative (AHRI), said Australian grain growers were world leaders in HWSC and arguably also in managing herbicide resistant weeds.
“There are now six different HWSC tools, and all were ultimately invented by Australian growers, with chaff lining and chaff tramlining being no exception,” he said.
“Research into the efficacy of these tools is catching up to their development and use by growers, and hence the Esperance RCSN group requested that case studies be compiled to increase grower knowledge about them.
“Chaff lining and chaff tramlining are part of an increasing trend where Australian growers are adopting HWSC tools that do not require burning of crop residues.”
Mr Newman said the case study publication ‘Investigating harvest weed seed control tools in low biomass crops in the Kwinana East Zone’ focused on the first aspect of HWSC – getting weed seeds into the front of the harvester.
“Crops in the eastern part of the Kwinana port zone, and other lower rainfall areas, are often sown on wide rows (more than 30 centimetres), and at moderate seeding rates. These factors, combined with dry conditions, are not conducive to growing the higher biomass crops that can more easily be targeted with HWSC,” he said.
“The most common tactics used by the case study growers to maximise weed seed capture in low biomass crops include increasing crop competition – to ‘hold weeds up’ in the crop canopy and reduce weeds in-crop; having a well set up harvester front; cutting crops low and harvesting weedy paddocks first.”