Chaff Lining

The chaff lining technique is clearly the cheapest in terms of capital cost.

Chaff lining involves making a simple chute to divert the chaff fraction (containing weed seeds) into a narrow row in the centre of the harvester instead of onto tramlines.

The chaff is then left to mulch while the residue can be chopped and spread to maintain ground cover. Although suited to controlled traffic systems, chaff lining can work in non-CTF systems if the harvester operates along the same runs for consecutive years.

Ask an Expert

What can I do at harvest to reduce my future weed burden?

As crops mature and harvesters begin reaping, consider the potential fate of seeds ripening on weeds that escaped in-crop control measures.
Peter Newman, WeedSmart’s western extension agronomist, says harvest time is an important opportunity to assess weed burden across the farm and be proactive about driving down the weed seed bank.
“Harvest can either be a super-spreader or a weed suppressing event,” he says. “Small patches of weeds can quickly expand when seed is blown out the back of the harvester. On the other hand, the harvester can be a powerful weed management tool if any one of the harvest weed seed control options are implemented.”
WeedSmart’s western extension agronomist, Peter Newman says efforts made to reduce the spread of weed seed at harvest will soon pay off for growers.
Australian growers have led the world in inventing and adopting harvest weed seed control tools such as impact mills, chaff carts, chaff decks and chaff lining, all of which can reliably destroy over 90 per cent of the weed seed that enters the front of the harvester.    
“In addition to harvest weed seed control there are several other actions in the WeedSmart Big 6 that growers can implement just prior to, during and immediately after harvest that will make a measurable difference to the weed burden in future growing seasons,” says Peter. “The WeedSmart Big 6 tactics are scientifically-proven to reduce the risk of herbicide resistance through diverse herbicide use and cultural control to prevent weed seed set.”
What can I do before harvest to manage late emerged weeds?
In brief: Scout for and map weedy patches. Consider sacrificing small areas of high density weeds. Swathing can be a very effective way to stop seed set of late emerged or resistant weeds. Collect weed seeds for herbicide susceptibility testing.
The details: Growers across Australia use a variety of methods to map weeds – from the simple to the sublime. ‘Dropping a pin’ using the tractor’s GPS mapping system as you travel through a weedy section when spraying or harvesting is easy and provides useful information about the distribution of weeds in the paddock. Many growers have their own drones and use them the collect images or video footage of the crop that can be viewed or analysed to identify high density weed patches.
Collect seed for herbicide susceptibility testing – knowing what still works is vital information for planning next season’s herbicide program. There are three herbicide testing facilities in Australia that are equipped to test weed seed samples – Plant Science Consulting, CSU Herbicide Resistance Testing and UWA Herbicide Resistance Testing.
Collecting weed seed before or at harvest is the most common method used. The collected seed must be mature, from green to when the seed changes colour. Before harvest, collect 30 to 40 ryegrass seedheads or several handfuls of wild oats seed. After harvest, it is common to find seedheads still in the paddock or samples of contaminated grain can be sent for analysis.
Keep samples from different locations separate and details noted on the bag. Only use paper bags (double layer) to collect and send seed samples. Ensure bags are sealed so that the samples don’t mix during transit.
Which harvest weed seed control tool is best for my situation?
In brief: There are six harvest weed seed control tools used in Australia – impact mills, chaff decks, chaff lining, chaff carts, bale direct and narrow windrow burning. Choose the one that best suits your system and budget.
The details: Impact mills are best suited to continuous cropping situations. Residues are retained and evenly spread. Chaff decks have lower capital cost and are well-suited to controlled traffic situations. Chaff carts are popular with grain producers who also run livestock. Bale direct is also expensive but has a good fit in locations where there is access to straw markets. Chaff lining is currently the best ‘entry level’ system and can be used in CTF or non-CTF systems, with best results where the harvester runs on the same track each year. Chaff lining has essentially superseded narrow windrow burning, overcoming the time required and risks involved in burning and reducing the loss of nutrients from the system.
If you haven’t used harvest weed seed control tools before, it doesn’t take long to build and fit a chaff lining chute ready for use this harvest season.
What should I be ready to do straight after harvest?
In brief: Spraying weeds immediately after harvest is fairly common practice. Weeds present may be close to maturity or fresh germinations of summer-active weed species.
The details: Some growers get in early with knockdown herbicide applied under the cutter bar when swathing barley or canola. Consider using the double knock strategy, heavy grazing pressure and possibly a soil residual herbicide that is compatible with your planned crop rotation. Pay particular attention to any weedy patches identified before or during harvest. Stopping seed set at every opportunity is the crux of an effective weed management program.
Give some thought to what might be the underlying cause of weedy patches – fixing problems such as pH and soil nutrition imbalances, waterlogging and spray practices that routinely deliver low doses of herbicide.


144: Regional Update – Andrew Ruhle, Farmer, Darling Downs and Western Downs

WeedSmart Week
Just a reminder that tickets are now able to be purchased for Esperance WeedSmart Week. It’s the first time in 5 years the event will be back in WA. It’s happening from the 17th to the 19th of August 2021. WeedSmart Week is designed to engage growers and advisors on WeedSmart’s Big 6 messages. You can get your tickets here.


Surprising chaff lining results and the future of mill technology

In this week’s episode, Jessica Strauss and Peter Newman catch up in person to talk about the highlights of the GRDC Crop Updates which have been taking place across the country.
Peter talks about what he presented at updates, including research done by Dr Michael Walsh from the University of Sydney on the efficacy of chaff lining. We also talk about research on weed seed mills and new machinery on the horizon. Pete also talks about his presentation on strip and disc systems and how they might fit into farming systems in WA.
We also discuss the Weed Chipper, developed by Dr Andrew Guzzomi and Dr Carlo Peressini from UWA and researchers from the University of Sydney. The Weed Chipper now has a commercial partner in Precision Agronomics Australia.
This project had received funding from the Grains Research and Development Corporation and was created in response to the growing concerns about herbicide resistance and the associated difficulties with fallow weed control.
Director of McFadyen Ag Consulting and Northern Panel Chair Andrew McFadyen about the effects of the Summer rain the Northern region has received.
Director of McFadyen Ag Consulting and Northern Panel Chair Andrew McFadyen
*In the podcast we chat about presentations which were stand-outs. We didn’t give the full name for ‘Keith’ – his full name is Keith Norman and he is a UK Farm Management Specialist.
We also talked about the model on HWSC Pete developed so you can calculate the cost of different HWSC options on your farm. You can download the model here.

Case Study

Esperance growers using chaff decks and chaff lining

Ten growers from the Esperance region of Western Australia who have adopted either chaff lining or chaff tramlining to help manage weeds have provided insights into their experience with these harvest weed seed control tactics.
Each grower spoke to Planfarm Agronomist, Nick McKenna, who documented their experience as part of a GRDC investment into the practical adoption of HWSC in the area in 2018.
Adrian Perks – Esperence grower using an EMAR chaff deck system for harvest weed seed control.
Nick says the growers all felt that they needed to use HWSC tactics to stay ahead of the weed pressure on their farms. One grower indicated that he would need to return to a mixed farming operation if he did not take action to reduce the weed numbers in his farming system.
“Several growers in and around Esperance had used narrow windrow burning and chaff carts in the past but had found it was often difficult to get a clean and safe burn on the residue, either because summer rain had made them too damp, or because the risk of fire escaping meant it required too much attention to burn safely,” he says. “Changing to chaff lining or chaff tramlining was an easy decision for these growers because there is no further effort required after harvest to get a kill on the weeds.”
Experience with chaff decks
The chaff lining system involves dropping a narrow line of chaff, including weed seed, behind the harvester. A chaff deck directs the weed seed-laden chaff into the permanent wheeltracks in a controlled traffic system. In both systems the chaff is left undisturbed.
Two of the ten growers interviewed were using the chaff lining system and eight had installed chaff decks on their harvesters. Each grower was satisfied with the results they were getting with the system chosen and there were few differences between the two systems.
“The two growers with chaff lining chutes had both built their chaff chutes themselves at minimal cost,” says Nick. “One person had moulded plastic chutes with a hot air gun and some tek screws and the other was made of metal sheeting. Both were attached to the harvester with pins and R-clips, making them easy to drop off to access the rear of the harvester. The total cost for materials and labour was about $1000.”
Chaff decks are a more expensive option – usually around $15,000 to $20,000 when fitted to new harvests. The commercially available chaff decks have two conveyor belts running at an angle to the harvester to deposit the chaff onto the wheeltracks. Installation on the harvester involves moving the chopper a fair way back to make room for the chaff deck. None of the growers Nick spoke to had experienced any operational problems with their chaff deck systems.
“One grower had made his own chaff decks specifically for John Deere S670, S680, S690 harvesters,” says Nick. “His system had two conveyors running across the back of the harvester, and did not involve as much modification work at the back of the harvester. It looked to be a simpler system, and cost about $13,000.”
Chaff decks deliver the weed-laden chaff onto the harvester wheeltracks.
The growers Nick spoke to all considered annual ryegrass to be their main weed. When using chaff decks the growers had observed greater germination of weed seeds on the high traffic wheeltracks, compared to the low traffic wheeltracks.
“Growers using chaff chutes said that very little grass germinates in the chaff lines,” says Nick. “I think this was partly because there is very little seed soil contact in the fluffy chaff left in chaff lines, and the chaff lines seem to do a good job of shedding water.”
“Clearly it is not essential to have a full controlled traffic system in place, but it is best if the harvester runs on the same tracks each year,” he says. “Some might consider that having no disturbance and very little germination is better than having weeds germinating on a portion of the wheeltracks; but either way they are concentrated and not spread across the whole paddock.”
When it came to seeding, none of the growers had run into difficulties when seeding through chaff lines. Some growers were running disc units either side of the chaff to minimise disturbance of the chaff and maximise the crop competition, so that the crop would suppress any weeds that did germinate.
“One advantage of the chaff deck is that the quantity of chaff is split between the two wheeltracks rather than all going into the one chaff line,” says Nick. “The growers all said that using a chaff deck or chaff lining allowed them to sow early with confidence, knowing they wouldn’t have an excessive number of weeds germinating in-crop.”
Those using a chaff deck observed that the ‘carpet of chaff’ on the wheeltracks significantly reduced the amount of dust generated during spray operations, giving them better coverage behind the boom, especially in hot conditions. In the day or two after rain the chaff can cause wheel slip during seeding on some soil types.
The experiences of these ten growers are documented in ‘Investigating the harvest weed seed control tools chaff lining and chaff tramlining (chaff deck) in the Esperance area – Grower case studies from the Esperance Port Zone’. The project was an initiative of the Esperance Port Zone Regional Cropping Solutions Network and the report was prepared by Nick McKenna and Peter Newman, Planfarm.
Nick McKenna, Planfarm agronomist visited 10 growers around Esperance, WA who have adopted chaff decks or chaff lining for HWSC.
The growers featured in this report are:

Mick Shutz – EMAR chaff deck
Adrian Perks – EMAR chaff deck
Col de Gussa – chaff tramlining using chutes
Carl Rasich and Henry Barlow – EMAR chaff deck
Steve Marshall – EMAR chaff deck
Elliot Marshman – EMAR chaff deck
Con Murphy – EMAR chaff deck
Mark and Hayley Wandel – chaff deck (continuous conveyor at 90 degrees to the direction of travel)
Patty Barber – chaff line (metal chute)
Mic Fels – chaff line (plastic chute)


Stepping into chaff lining

Peter Newman, AHRI / Weedsmart Western region agronomist, is a firm advocate of harvest weed seed control (HWSC). In this practical publication Peter provides all the details you need to get started with this important tactic in the war against herbicide resistant weeds.
Chaff lining chute.
Use this guide to ensure you are:
1. Getting the weed seeds into the front of the harvester
2. Getting weed seeds out of the rotor
3. Keeping weed seeds in the chaff stream
4. Deliver weed seeds into the HWSC tool – chaff line chutes
Comparison of chaff lining and chaff tramlining
Download ‘Tools and Tips – Setting up for chaff lining’
WeedSmart Big 6 – including Harvest weed seed control

Ask an Expert

Does chaff in a chaff line suppress weeds?

with Annie Ruttledge, Weeds researcher, DAF, Queensland
In the wake of rapid adoption of chaff lining, the newest harvest weed seed control tool developed by Australian farmers, a substantial research effort has been made to validate the efficacy of this practice.
Chaff lining involves depositing weed seed-laden chaff in a narrow line behind the header. Some growers using this practice have suggested that as the chaff in the chaff line rots away, much of the weed seed also decays in the process. Researchers working across the northern grains region have now gained a deeper understanding of what happens to weed seed in a chaff line.
Dr Annie Ruttledge, DAF Qld weeds researcher has been investigating weed emergence from chaff lines.
Department of Agriculture and Fisheries, Queensland weeds researcher Dr Annie Ruttledge and several collaborating scientists have been looking into different aspects of weed seed decay and weed suppression in the chaff line.
“Non-herbicide tools like chaff lining are very important to help manage the onset and spread of herbicide resistance in weeds,” says Dr Ruttledge. “The idea with harvest weed seed control tactics is to collect any weed seed present at harvest height, usually above 15 cm. With chaff lining, these weed seeds are deposited in a narrow line of chaff behind the harvester.”
“Burial in the chaff line can suppress emergence in some weed species, but it does not guarantee that no weeds will emerge from chaff lines,” she says. “Harvest weed seed control tools like chaff lining and chaff tramlining concentrate the weed seed into confined zones where emergence can be monitored and action taken as required, without treating the whole paddock.”
Chaff lining (and chaff tramlining) deposit weed-laden chaff in a narrow line behind the harvester or directed onto the tramlines.
Does the chaff line suppress weed emergence?
Short answer: Yes, if the weed seed is buried deeply enough in the chaff. Many weeds in no-till and reduced-till farming systems prefer to germinate on the surface where there is plenty of light.
Longer answer: Our trials investigated the effect of chaff on germination rates of annual ryegrass and common sowthistle. The sowthistle seed was more readily prevented from emerging than annual ryegrass seed, probably due to the different requirements of the species for light. Maximum suppression of annual ryegrass emergence was achieved with a chaff load of 42 t/ha, which can be feasibly produced in a 3.5 t/ha cereal crop. In contrast a chaff load of just 12 t/ha of wheat chaff was sufficient to suppress emergence of common sowthistle seed.
Work done by our collaborator Dr John Broster, CSU found that chaff from cereal crops generally provided better suppression of annual ryegrass compared to canola and pulse chaff. For all chaff types the higher the rate per hectare the better the suppression.
One of the experiments involved determining the level of chaff required to effectively suppress emergence of annual ryegrass and common sowthistle.
What’s the difference in suppression in chaff lines compared to chaff tramlines?
Short answer: Chaff tramlining effectively halves the amount of chaff in each line, potentially reducing the suppressive potential of the chaff.
Longer answer: Placing a single line of chaff behind the harvester (or directing all the chaff from a chaff deck into one tramline) maximises the amount of chaff and therefore the level of weed suppression. Different crop types, sowing rates and crop yield all influence the quantity of chaff produced.
In addition to looking at suppression of emergence, we looked at weed seed decay under field conditions. In these trials there was no evidence that weed seeds rotted more rapidly in a chaff line than on the soil surface. However, we expect that environmental conditions play a large part in weed seed decay so the results could vary according to season, with more rotting likely in a wet year than in a dry year. The depth and persistence of chaff cover and the type of weed species are other factors that would influence seed persistence in chaff lines or chaff tramlines.
Harvest weed seed control tactics aim to collect weed seed at harvest and concentrate it in a small zone where weeds can be targeted at a fraction of the cost of whole-paddock treatments.
What are the options for treating the weeds in the chaff line or tramlines?
Short answer: Farmers are leading the way with practical solutions to manage weeds along chaff lines and chaff tramlines.
Longer answer: Some growers use an optical sprayer or a boom with nozzles only operating on the chaff line or tramlines to apply a mix of herbicides that may be too expensive to apply to the entire paddock. Weed seed that is collect at harvest and placed in the chaff line, may have survived in-crop herbicide applications and may be herbicide resistant. Susceptibility testing can help identify herbicides that can provide effective control.
Non-herbicide options are to wait for germination and chip or trample the weeds. In a mixed farming operation, sheep can graze the chaff lines rendering most of the weed seed unviable, and the sheep will benefit from an additional feed source.
Growers who have been using chaff lining and chaff tramlining for several years report that the high concentration of weed seed leads to a high level of competition between the weeds and this is compounded with competition from the following crop. Over time, seed set reduces and any weed seed produced will be collected and returned to the chaff line the following year. When chaff is deposited on the wheeltracks, weeds that emerge face dry, compacted conditions and are often subject to frequent passes with heavy machinery.
This chaff tramline was sprayed out using a shielded sprayer.
Does it matter if I use a draper or a stripper front?
Short answer: No, not in terms of amount of weed seed harvested, provided you set up and operate with weed seed collection in mind.
Longer answer: Our collaborators Dr John Broster, Dr Michael Walsh and Annie Rayner conducted trials with stripper and draper fronts at two trial sites. The results at one site showed that it is possible to achieve the same level of weed seed collection with the two harvester front options. At the other trial site, the stripper front was not as effective as a result of wider row spacing, higher operating height and faster operating speed compared to the draper front at the same site. The key to success with chaff-only harvest weed seed tools is getting the weed seed in the front and effectively separating the weed seed and chaff from the straw component. The WeedSmart website provides practical information about setting up different harvesters and operating them for effective harvest weed seed control.
Bear in mind that a stripper front will generate a lot less chaff than a cutter type front, and so this is likely to influence weed suppression and the rate of weed seed decay.

Ask an Expert

Can sheep turn weed seeds and chaff into cash?

with Ed Riggall, AgPro Management consultant, WA
Chaff carts have been doing a great job in the battle against herbicide resistant weeds and are finding a valuable niche, particularly in mixed farming enterprises in western and southern cropping regions.
AgPro Management consultant, Ed Riggall has been validating the anecdotal evidence of the value of chaff heaps as a stock feed for the past three years and has proven that there is money to be made from using chaff heaps (and probably chaff lines) as a summer feed source for sheep.
AgPro Management consultant, Ed Riggall has been validating the anecdotal evidence of the value of chaff heaps as a stock feed for the past three years and has proven that there is money to be made from using chaff heaps (and probably chaff lines) as a summer feed source for sheep.
“Using paired paddocks on farms in different regions we measured the changes in sheep weight over a period of 6 weeks and compared the performance of sheep grazing paddocks with chaff piles with that of sheep from the same flock grazing paddocks where the chaff had been spread,” he says. “Data was collected in canola, wheat, oats and barley fields in eight locations in Western Australia over three years.”
Ed analysed the feed value of the chaff heaps from different crops and while the results varied considerably, canola has proven to be a consistent performer. This is due mainly to the higher protein level compared to cereals, which enables the chaff piles to be better digested. The cereal chaff heaps were all similar in feed value with around 4% crude protein and ME over 7 MJ/kgDM, indicating that provision of additional protein, such as lupin grain, would be required for the sheep to make full use of cereal chaff piles.   
“The results showed that sheep on chaff piles gained an average of 2 kg in the first three weeks, 500 g more than sheep grazing stubbles (no chaff heaps),” he says. “At the end of six weeks grazing the sheep with access to chaff piles had gained about 100 g while sheep without access to the chaff piles had lost almost 2 kg compared to their starting weight.”

In Merino flocks this small positive net gain per head for sheep grazing chaff heaps is worth a serious amount of money, spread across the whole mob, in the form of improved condition score, increased lambing percentages and reduced summer feed costs. When you add in the value of chaff management as a weed seed control measure to combat herbicide resistant weeds, the return quickly pays for the investment in a new chaff cart.
Meat & Livestock Australia (MLA) is currently funding a 3- year demonstration site with the Gillamii group based in Cranbrook, WA to further evaluate the value of grazing chaff heaps.
Do all sheep readily graze the chaff heaps?
Short answer: No, flocks can take some time to accept the chaff heaps as a feed source.
Longer answer: Livestock usually take time to adjust to a new feed and will tend to preferentially graze familiar feeds, even though they might be scarce or of lower feed value. It helps to include some older or more experienced individuals in the flock to show the others that it is good feed. In cereal paddocks, there is a biological limit to the amount of high ME feed animals can consume if there is insufficient protein available. Providing some supplementary grain will address this problem. 
Flocks can take some time to accept the chaff heaps as a feed source. Including some more experienced animals in the flock can help.
What did the economic analysis show?
Short answer: Internal rate of return of 21% on the purchase of a $80 thousand chaff cart.
Longer answer: The analysis was done on a model farm of 2000 ha where 50 per cent of the area was cropped and the rest was pasture. Over summer, 9 DSE (7500 sheep) grazed chaff heaps on the 1000 ha cropped area. The average weight advantage of sheep with access to chaff heaps over those that did not was 3.1 kg/hd (where half the area was canola and the rest cereal). Using a feed conversion rate of 3:1, the sheep with access to chaff piles consumed $250 worth of feed for ‘free’. If the farmer invested $80 thousand in the chaff cart, spent $20 thousand in repairs and maintenance and sold it for $20 thousand in 20 years the internal rate of return on the initial investment is a huge 21%.
Adding a chaff cart to a mixed farm is a great example of a practice that is good for both the sheep and the cropping enterprises. 
Grazing sheep on chaff heaps can help to quickly repay the money invested in the purchase of a new chaff cart.
Do sheep spread weed seeds from the chaff piles across the paddocks?
Short answer: No, very few weed seeds remain viable after passing through a sheep’s gut.
Longer answer: Farmers who routinely use sheep to graze chaff piles say that there is no noticeable spreading of weeds across the paddocks. DAFWA research has validated this observation to prove that weed seed is not spread and that only 3 per cent of weed seeds remain viable after passing through a sheep’s digestive system.
Do sheep spread nutrients from the chaff piles across the paddocks?
Short answer: Probably yes. The question is how evenly? This will depend mostly on stocking rate and other variables.
Longer answer: While there is little to no documented research about nutrient redistribution in chaff pile paddocks, there is for other grazing systems so it stands to reason that some nutrients would be spread back across the paddock. A new area of research is to consider the economic benefits of sheep grazing chaff lines, which may also have a great benefit when it comes to nutrient redistribution.
More resources

Ed Riggall – Chaff as sheep feed webinar
Case study: Ben Webb, Kojonup WA


Wagga WeedSmart Week; chaff lining + carts + cotton update

In this choc-a-block podcast, hosts Jessica Strauss and Peter Newman investigate chaff lining and chaff carts, get an overview of WeedSmart Week and a seasonal overview of cotton.

Mick McClellend farms in the Mallee in Victoria and has been using chaff lining in his farming system for the last three years. He gives an overview of the successes he has had using it.
Tom Lewis from Tecfarm manufactures chaff carts. He chats about the benefits of using one for weed control. Chaff carts can be used in mixed and broadacre farming systems.
WeedSmart Week is not far away, with the forum kicking off on August 21, and the farm visits following on August 22 and 23. Greg Condon talks about who will be presenting and what farmers and advisors can expect from the day. For more information about WeedSmart Week in Wagga and to register, click here.
The Cotton Research and Development Corporation (CRDC) has recently jumped on board as a sponsor of WeedSmart. We welcome them aboard and get a seasonal update and find out what they’re doing weed management-wise from CottonInfo’s Regional Extension Officer Annabel Twine and Tech Specialist Eric Koetz.

Subscribe to the WeedSmart Newsletter