Case Studies

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Case Study

Andrew Kenny, Badgingarra WA

Andrew and Gina Kenny farm at Badgingarra, in WA’s west midlands using an integrated program of crop rotation, mouldboard ploughing, grazing and chaff lining to keep their weed numbers very low. Andrew’s parents, Mike and Sara, arrived in the Badgingarra district to farm in 1959 and started clearing the land for cropping, at about the same time cropping land was also being developed around Esperance. Badgingarra farmer, Andrew Kenny has used TT, and more recently RR, canola to take advantage of different chemistry and weed control tactics. “There is a fault line that runs through the property with distinct soil types on either side,” says Andrew. “On one side of the line is our best cropping soil – clay through to pea gravel; on the other side is white sand with very limited water holding capacity, which we use mainly for grazing.”   Grazing to maximise productivity About 60 per cent of the 4150 ha property is used for continuous cropping and the rest for grazing sheep. The Kennys grow some hay for their own use and the sheep also graze the crops – mainly barley, and sometimes wheat and canola – from mid-June to mid-August. For over ten years the Kennys have run 5500 ewes in two flocks – a 4000-ewe self-replacing merino flock and 1500 Prime SAMM ewes mated to Poll Dorset terminal sires. Producing both wool and meat, the sheep are an important component in the business. SAMM are a dual-purpose sheep that was later further developed to produce a heavy slaughter lamb at a young age, as well as good quality wool. “We grow mainly Bass and Planet barley, which we will graze two or three times with 2500 hoggets before allowing it to finish for grain,” he says. “These varieties both tiller well and respond quickly after grazing to the first node stage.” Sheep utilise 40 per cent of the farm where the sandy soils do not retain sufficient moisture for cropping. The Kennys retain lupin seed, make hay, graze crops, chaff lines and stubbles and use the sheep to provide a double knock effect. Low weed numbers allows dry sowing Once the season breaks, the Badgingarra area can generally rely on good rainfall through the growing season. In 2018 there was a late break, resulting in Andrew taking a risk and sowing 75 per cent of their crop dry. That year he saw the benefits of earlier sowing and is confident that their weed numbers are now low enough to make dry sowing a safe practice. “On the heavier soils we grow canola, wheat and barley. Sandier soils that are lower in the landscape have better nutrient levels than those at the top of the landscape, and are suitable for cropping lupin, wheat and barley.” Barley has been a consistently strong performer in recent years so the area has increased. Lupins provide a good break from cereals and provide a high protein feed that is easy to store on farm and kept primarily as a drought reserve. The Kennys introduced canola to their cropping program in the 1990s and have used TT canola, swathing and spraying under the swather with glyphosate as key tools in their weed control program. They also crop top Barlock lupins to stop seed set. Andrew rotates herbicide modes of action through the crop cycle, particularly with the pre-emergent chemistry – using propyzamide in lupin, trifluralin in canola, Sakura in wheat and trifluralin + metribuzin in barley. He also targets weeds ahead of seeding with a double knock of glyphosate then paraquat, or uses Spray.Seed®(paraquat/diquat) on its own. In weedy paddocks Andrew avoids growing two barley crops in a row, choosing instead to switch to canola or lupins to utilise other herbicide MOA, but in paddocks with very low weed numbers he will occasionally grow barley on barley to boost profitability. With few in-crop options for ryegrass control, Andrew relies on having clean paddocks at seeding and robust pre-emergents. To ensure the crops get off to a good start, Andrew buys in hybrid canola seed and uses a mobile contract seed cleaner to clean farm-retained cereal and lupin seed. He has increased crop competition using a paired row boot on a 30 cm spaced tyne bar to give an effective row spacing of 7.5 cm. “The tynes are custom built and we use them for sowing all our crops,” he says. “They probably work best in the cereals, but we don’t have any problems in the other crops either. The aim is to do everything we can to increase crop germination, which gives us more crop and less weeds for the same amount of effort.”   Burying glyphosate resistance Andrew says annual ryegrass and wild radish continue to be their most challenging weeds and he has recently added RR Truflex canola hybrid to the rotation to give more options to use glyphosate. “I am very conscious of the risk of accelerating glyphosate resistance and so we also use mouldboard ploughing to bury glyphosate resistant weed seeds and improve the wettability of the sandy soils,” he says. “Mouldboard ploughing has fixed non-wetting issues wherever we have used it and this improves crop germination, but on the very sandy soil fixing the non-wetting is not enough to sustain cropping, so these poorer soils remain under pasture.” The benefits of mouldboard ploughing for weed control varies according to soil type. Andrew has seen it most effective on their sandy soils but found it difficult to achieve full inversion on the gravel country.   Chaff lining suits sheep Ten years ago Andrew began narrow windrow burning for harvest weed seed control, mainly in cereals and only in weedy paddocks. They had good results in weedy paddocks but after eight years Andrew was looking for an alternative that would have less impact on nutrients and require less labour. “We graze the stubbles over summer and the sheep would make tracks through the narrow windrows, which increased the number of places the windrows needed to be lit,” he says. “In 2017 we decided to give chaff lining a go.” Although the farm is not set up for controlled traffic, Andrew does run the harvester on the same lines each year, allowing him to place the weed seed in the same place each season. With the chaff lining chute as a semi-permanent modification to the harvester, Andrew is now able to implement HWSC in all crops and all paddocks. With the chaff lining chute as a semi-permanent modification to the harvester, Andrew is now able to implement HWSC in all crops and all paddocks – he can just forget that it’s there! “The chute, baffle and spreader chopper were fabricated and fitted for around $6000,” he says. In addition to concentrating the weed seed, chaff lining also concentrates any crop seed losses out the back of the harvester. This means the sheep can make use of any lost grain and Andrew expects the productivity gains from chaff lining would be similar to that measured for chaff dumps. “In 2018 we had a high level of weed germination in the chaff lines but we did not treat them differently to the rest of the paddock,” says Andrew. “The chaff chute left clumps in the paddock and I thought this might lead to seeding blockages, but in reality, the tyne seeder easily worked through the fine chaff material.” Andrew expects there would be some rotting of the chaff and weed seeds in years with wetter summers, but this has not yet been put to the test. What is evident though is the impact of higher soil moisture retention under the chaff lines. Sheep graze the stubbles and do a good job of stopping seed set on any green ryegrass that escaped capture at harvest. The sheep also reduce the overall stubble load and trample the chaff lines, making sowing easier.   Other resources Podcast – Mouldboarding + Chafflining + Grazing
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Case Study

Mat Freeman, Walkaway WA

Mat Freeman farms an aggregation of cropping properties at Mullewa and Walkaway in the Geraldton Port Zone of WA. Across the aggregation he has been systematically mouldboard ploughing since 2011 to tackle the non-wetting sands, and deep ripping has been practiced for around 30 years to alleviate compaction. While fixing the constraints associated with non-wetting sands is the primary reason for mouldboard ploughing, there is also a weed control benefit. Mat Freeman, Walkaway WA has used mouldboard ploughing to fix non-wetting sands and bury weed seeds. “Having effectively buried the weed seed bank with the mouldboard ploughing, the plan is to leave the subsoil undisturbed for as long as possible,” he says. “Hard-seeded weeds such as wild radish can remain viable in the soil for several years and can germinate if they are brought back up to near the soil surface.” Inverting the profile buries weed seed and brings some clay up from depth. Annual ryegrass and wild radish are the main weed species on the farm and Mat is making the most of the re-set value of mouldboard ploughing to keep weed numbers low going forward. Effective amelioration operation To achieve full inversion of the soil profile, the soil needs to be moist. The amelioration program also involves the removal of obstacles, applying limesand and then ploughing to a depth of about 35 cm. This is usually done after a lupin crop where there is the least amount of crop residue on the soil surface. The following year Mat spreads more limesand to treat the acidic subsoil that is brought to the surface. “Starting with a pH of around 5 on the surface and 4 in the subsoil, we are aiming for a pH around 5.5 on the surface and 5 at depth,” he says. “To achieve this requires about 4 t/ha limesand applied over the two years to treat both the topsoil and subsoil.” “Mouldboard ploughing needs to be done well, in wet soil and with not too much crop residue on surface,” he says. “We are close to completing the ploughing program across the whole farm and expect a long-term productivity benefit from the liming and mouldboard ploughing operation as a result of improved pH.” After using contractors for the first few years Mat now has his own mouldboard plough, and has committed to a program of ploughing 500 ha each year ever since 2011, along with regular deep ripping. When he first started deep ripping, Mat used a ripper that worked to a depth of about 35 cm but he now has a ripper that works to a depth of around 70 cm. To avoid bringing the weed seed back near the surface he uses straight, rather than C-shaped, shanks to shatter the compaction at depth without bringing weeds or clay to the surface. Harvest weed seed control decisions “The weed program here is about attacking them from all angles,” says Mat. “We do what we can to avoid letting weeds set seed. We have been running a Seed Terminator impact mill for a couple of harvests, having previously used narrow windrow burning for harvest weed seed control.” Mat has replaced narrow windrow burning with an impact mill for harvest weed seed control. Although narrow windrow burning worked well, Mat found there was a big risk of burning everything after a big cereal crop followed by lupins or canola, and it was hard to get the right weather conditions for burning. He was also concerned about the cost and long-term impact of lost nutrients. The farm is full CTF for harvest so Mat considered chaff lining as a possibility using RTK to ensure the chaff lines went on top of each other to then be burnt. With the soils being generally low in moisture Mat thought it was unlikely that the chaff would rot and was concerned that he might ‘have the chaff lines forever’. He also considered a chaff deck but decided it was not the best option for the farm and chose instead to invest in impact mill technology. Crop-topping in lupins has been part of Mat’s weed control program for a long time and he sees value in continuing with this tactic even though he now has the impact mill on the header. Rotation weed control tools “There is often 20 per cent of the farm sown to lupins and crop-topping is a good way to control any lodged or fallen grass weeds,” he says. “The outside laps in each paddock often have more weeds because it is harder to plough and the weed seeds are not always buried as well as they are in the main paddock area. Crop-topping is an effective way to help minimise weed seed set in these areas, in addition to the destruction of the weed seeds that go through the impact mill.” Crop topping in lupins is particularly useful for stopping seed set in lodged ryegrass that might not be picked up by the harvester. In canola Mat has previously used swathing and spraying under the cutter bar but is finding that direct heading works just as well. Crop rotation varies slightly on different farm units but generally follows a wheat, lupin, wheat, canola sequence. Some of the very light and fragile sands have not previously been suitable for canola but Mat has been able to introduce canola on these soils following liming and mouldboard ploughing. Pre-emergent herbicides are used for all crops – except straight after ploughing where the low organic matter levels can lead to more severe crop damage. After mouldboard ploughing and liming Mat follows a crop rotation of wheat, lupins, wheat, canola. He is planning to reduce the row spacing from 12 inch to 10 inch with his next planter to increase crop competition. Mat uses a tyned seeder with 12 inch row spacing but plans to change to a 10 inch row spacing with the next seeder to go the next step in crop competition for weed control. Cereals are sown on the CTF lines but Mat prefers to sow canola and lupins at 30 degrees to achieve better establishment in these sandy soils. This angle gives him the option to change direction back and forth each year and is not as rough as sowing on a 45 degree angle. Factors other than crop competition tend to influence variety choice but Mat looks to maximise crop competition through improved establishment, better soil fertility, better access to moisture and is looking to narrow the row spacing in the future.   Deep ripping for yield In addition to the mouldboard ploughing to ameliorate non-wetting, Mat also uses deep ripping to improve crop production. Deep ripping is done every second year after lupin and canola crops and has made marginal soils profitable, which has led to a significant increase in overall farm profitability. Deep ripping trials in 2015 confirmed that there were significant benefits in addressing soil compaction and improving water penetration into the profile, particularly in wheat where ripping to a depth of 600 mm generated a yield benefit of almost 1 t/ha.   * Grain price wheat = $270/t and cost shallow ripping = $45/ha and deeper ripping = $75/ha. At Walkaway deeper ripping and topsoil slotting (inclusion plates) was the highest yielding treatment. Visual observations showed more plant roots deeper in the slots than un-ripped and NDVI measurements indicated a higher biomass in the deeper ripping treatments during the season. Source: Deeper deep ripping and water use efficiency, GRDC RCSN Geraldton GER9, by Craig Topham, Agrarian Management and Bindi Isbister, Precision Agriculture “Deep ripping has really boosted yield and we find the crops persist better between rain events and finish better at the end of the season. The crop develops a deeper root system that can access more water at depth and the result is better yield and grain quality,” he says. Although the mouldboard ploughing effect persists for several years, the sandy soils quickly settle and develop a hardpan at depth, even without machinery traffic. Mat aims to rip every second year if there is sufficient soil moisture in autumn, preceding sowing, taking care not to bring weed seeds to the surface. The CTF system is based on 12.2 m centres for the sprayer, planter and harvester and was installed in each paddock after the initial mouldboard ploughing to preserve the benefit of this operation. Using this soil amelioration program, Mat is now bringing land into crop production that was previously only used for grazing.
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Case Study

Andrew & Jocie Bate, Gindie Qld

The idea of small, lightweight machines replacing heavy tractors was prompted by Andrew’s determination to alleviate soil compaction on the 50 to 150 cm deep black cracking clays at Bendee. Ninety per cent of the area is sown to winter crops, which are grown primarily on soil moisture stored over the previous summer. Andrew and Jocie Bate, farmers first and foremost. A desire to alleviate compaction on their farm at Gindi, Central Queensland is the driving force behind their agtech venture into robotics. “Central Queensland winters are generally dry and we rely on moisture stored during summer storms and retained through zero tillage and stubble cover,” says Andrew. “Wheat provides the best stubble and chickpea is our most profitable crop so we just rotate between these two crops. About one year in five we will have the opportunity to plant a summer crop and we’ll double crop a small area to mungbeans or possibly forage sorghum or dryland cotton.” The Bates also run a cattle enterprise separate from their cropping, except for limited grazing of forage sorghum one in three years in just one paddock. They usually avoid having the cattle on the cropping paddocks due to the compaction and the proliferation of hard to control weeds that can occur. Moisture seeking improves crop reliability Deep, or moisture-seeking, planting has been a valuable tactic for the Bates, particularly in chickpea crops. In years where there is no summer crop in the ground they are able to plant as early as April, without waiting for planting rain. “We plant chickpea seed up to 25 cm deep into moist soil,” says Andrew. “Wheat is more difficult to establish this way but varieties like Mitch that have a strong coleoptile can be planted up to 13 cm deep into moisture. It is still hot here in April and the temperature can reduce coleoptile length, so planter setup is critical to get even emergence from depth. If we can achieve a good even stand, the crops have access to good moisture to sustain vigorous early growth.” Mitch is not a prime hard wheat variety so Andrew only grows it when soil moisture is limiting, knowing that it will push out of the ground even in tough conditions. Wheat stubble is essential for their farming system, so Andrew does everything necessary to ensure a good wheat crop is established. The deep sowing technique has proven almost bullet-proof over the last 20 years with wheat being reliably established in eight years out of ten, and they have had 100 per cent success with chickpeas. In most years Andrew grows their crops on stored moisture plus one inch of early rainfall and hopes for one follow-up rainfall event in-crop. In-crop weed control “We put a lot of emphasis on having clean fallows and achieving strong emergence of the crop,” says Andrew. “This is critical to maintaining our low weed numbers in our winter crops. All our crops are sown on 50 cm row spacing, except sorghum, which is sown in meter rows. In the recent dry summers, we have opted to grow forage sorghum rather than grain sorghum as a risk management strategy due to limited stored moisture in the profile.” Metsulfuron-methyl (e.g. Ally, Group B) and Tordon 242 (Group I) herbicides are providing reliable in-crop control of broadleaf weeds in wheat crops and has a useful level of soil residual activity that reduces the incidence of weeds germinating late in the season. Andrew says the dry conditions in Central Queensland winters results in minimal in-crop weeds, so there is little pressure to adopt harvest weed seed control tactics – their focus is on controlling summer fallow weeds. Wheat provides the essential stubble cover to maximise soil moisture conservation over summer to underpin the following, and most profitable, chickpea crop. In the chickpea and mungbean crops Andrew uses Group A chemistry, mainly haloxyfop (e.g. Verdict), to manage grass weeds. While he avoids residuals as much as possible to maintain flexibility in the rotation, he uses simazine (Group C) across all of his chickpea and isoxaflutole (Group H, e.g. Balance) on about a quarter of the chickpea area to provide long-term residual control of many problem grass and broadleaf weeds, including glyphosate tolerant feathertop Rhodes grass, sowthistle, and fleabane in crop and during the following summer fallow. “We use minimal in-crop herbicide and rotate between chemical groups though the crop rotation,” says Andrew. “But really we rely mainly on our fallow management to have clean paddocks to plant into.” Within the next few years all the weed control and planting at Bendee will be done by the robots. Andrew and Jocie will soon dispense with their self-propelled spray unit and just use their robots supplemented with blanket aircraft applications on less than 10 per cent of the farm area. The weediest paddocks on Bendee still only require herbicide to be applied to 20 per cent or less of the area. The robots can also do broadacre spraying but this will be more practical once the docking and refilling capability is implemented. “We generally have dry harvest conditions so most of the soil compaction is done by the sprayer in wet conditions,” says Andrew. “Right from the start this has been a driving force behind the development of the SwarmBot concept.” There are currently two SwarmBot-5 robots with WEEDit attachments working on Bendee. The two robots cover 24 ha/hr and can work 24 hours a day if conditions permit. With weather stations now onboard, the robots will drop into sleep mode when the weather conditions are outside acceptable parameters and then wake up and resume work when the conditions are good. Robots and the optical WEEDit sprayer have combined to reinvent the fallow weed management system at Bendee Farming. With more passes, there are more opportunities to spray weeds when they are small and easy to kill, and rotate chemical groups more often. Summer weeds are of greatest concern at ‘Bendee’, with sowthistle, fleabane, wild sunflower and feathertop Rhodes grass being the main targets for fallow weed management. These key species are a bigger problem in years with wet summers, where the weeds can get away during the fallow period and then haunt you in the following crop. Andrew is working on setting up the robots to wick-wipe weeds such as milk thistle growing above the canopy in chickpea and stop seed set. Robots and the optical WEEDit sprayer have combined to reinvent the fallow weed management system at Bendee Farming. While Andrew acknowledges that calendar spraying is generally a bad idea with regular spray rigs, it is a really valuable tactic when you have robots at your disposal. “We are doing more frequent passes with the robots applying knockdown herbicides and it works well because we are always spraying fresh, small weeds and minimising seed set, therefore reducing the risk of herbicide resistance,” he says. “We are also better able to control weeds that are considered hard to kill with glyphosate, such as wild sunflower, feathertop Rhodes, sowthistle and fleabane, which are all much more susceptible to glyphosate when they are very small.” “With robots, it’s not about how many acres you can spray in one day – it’s more about how many passes you can do in one season. More passes, gives you more opportunities to kill weeds when they are small and easy to kill and rotate chemical groups more often.” The benefit of the robot and optical sprayer combination is that both operate equally well at night as in the day, and so can be out spraying whenever the conditions are within the optimal range of temperature, wind speed and humidity. Andrew can also use a wider range of knockdown options such as glyphosate (Group M), paraquat (Group L), glufosinate-ammonium (Group N), and proprietary mixes such as amitrole (Group Q) plus paraquat when spot spraying to reduce costs. “Running the robots weekly to hit weeds hard opens up untapped potential in existing herbicides because they are being spot sprayed on small weeds only,” he says. “This avoids the need for residuals in fallow and there’s even the option to add spot cultivation if required.” “With robots you can spot spray a paddock that an agronomist would say was not worth spraying. Having a low weed seed bank means there is less pressure to go spraying straight after rain because there will be fewer weeds germinating.” With 4000 ha of summer fallow to keep clean Andrew is also re-evaluating their double-knock strategies using the robots. He is finding that the proprietary mix Alliance (Group Q + L) is a good double knock for glyphosate and he often puts two compatible modes of action in the same tank mix. “The WEEDit makes double-knocking much more practical, and using the robots means the workforce and family have less exposure to chemical,” says Andrew. “We can afford to double-knock more often.” Where weedy patches have established Andrew employs patch management strategies to prevent seed set. Intensive herbicide treatments or use of the robotic cultivator are now options at Bendee, particularly if the weed escapes are large plants. “Ideally we are working toward the development of microwave technology for the robots rather than targeted tillage,” says Andrew. “Microwave weeding is only practical on a robotic platform and when applied using weed detection there is a big reduction in the energy required. For us, the key advantage is the zero soil disturbance – a lot of weeds thrive in a disturbed or cultivated environment even if the disturbed area is small.” Andrew and Jocie see microwave technology as a good non-herbicide option that is compatible with robots and no-till farming systems. This prototype is proof of concept. Along fencelines and paddock edges Andrew has reduced his use of 2,4-D in the last few years due to the impact 2,4-D has on glyphosate efficacy on key species such as sowthistle and feathertop Rhodes grass. Instead he is now doing more passes with broadleaf herbicides on borders and hand-spraying feathertop Rhodes grass. “Buffel grass provides good competition for weeds along fences,” he says. “It is very important to just use broadleaf selectives and preserve the buffel, otherwise you end up with all sorts of weeds.” Robotic planting The Bates have built a planter that the SwarmBot can tow and in time they expect to have the robots completing the whole planting operation. Previously the SP sprayer was used to apply the blanket spray in front of the tractor with the planter but now the two robots can follow each other, one applying the blanket spray and one towing the planter, with both operating at 10 km/hr. The controlled traffic system at Bendee is based on a 12 m header front, spraying band of 12 m and the 6 m robot planter will make extra wheel tracks but apply far less weight to the paddock than the conventional planter that has wheels every 4 m, with each wheel applying more weight than a whole robot. SwarmBot planter set up for planting cotton. Other resources: SwarmFarm: Target small weeds year round Robotics opens up more non-herbicide options
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Case Study

Beefwood Farms, Moree NSW

The combination allowed for more efficient and targeted use of herbicides through double knocking and more timely and frequent applications to treat weeds at their most susceptible growth phase.   Beefwood Farms manager, Glenn Coughran. With low weed density across the 11,000 ha operation Glenn is able to avoid the use of pre-emergent herbicides, which have limited crop rotation choices in the past, particularly in years where summer rainfall has been low. Glenn is keen to see ‘green-on-green’ optical weed detection become a reality and is working closely with AgriFac to have this technology integrated into their spraying equipment. Located between Goondiwindi and Moree on the western side of Newell Highway, Beefwood Farms is an aggregation of six neighbouring properties, all operated from the central workshop area. Gerrit and Pam Kurstjens, originally from Grubbenvorst, the Netherlands, purchased the aggregation in 2006 and began the transition from livestock to a controlled traffic continuous cropping operation using the latest technologies to achieve greater efficiencies. Beefwood Farms owner, Gerrit Kurstjens (left) with his daughter Marieke and MCA Ag agronomist Stuart Thorn. “Our cropping program has to respond to the weather, and to a lesser extent prices, but normally the sequence is wheat then barley then chickpea or left out for winter and into sorghum in summer,” says Glenn. “We are keen to try dryland cotton but unless we have conditions that result in a full profile of soil moisture it just isn’t a feasible option.” “Each year we fallow about 20 to 25 per cent of the farm in winter in preparation for planting the summer crop,” he says. “If the sorghum is off soon enough these paddocks are usually double cropped back to chickpea the next winter. This tactic gives us two consecutive winters to work on any winter grass weeds, particularly wild oats, using different chemistry.” But with a string of very dry years recently the opportunities to grow summer crops has been limited. They generally avoid using residual chemistry in summer due to concerns over the possibility of insufficient late summer rainfall to breakdown the chemical prior to planting the winter crop. “We have been caught using imazapic in a summer fallow and then we didn’t get the necessary 150 to 200 mm of rainfall needed to break down the residual,” he says. “This meant we had to grow Clearfield barley, which was a good option in the circumstances, but you are restricted to just a few varieties and we don’t want to be limited in our crop choices too often.” The CTF system is based on 3 m machinery wheeltrack centres, 12 m headers, 24 m planters, 48 m self-propelled boom sprayers and 24 m WEEDit optical sprayer. Beefwood operates two NDF disc planters for the winter cropping program – a double bar machine planting on 33 cm row spacing and a newer single bar machine where the closest spacing they could achieve is 37.7 cm. The sorghum crops are sown on 1.5 m row spacing. “We can’t sow the cereals any closer to increase crop competition but we have seen a response to increased seeding rates,” says Glenn. “Also, the whole farm is planted east-west to maximise shading in the inter-row. This helps a little in the sorghum too where increased seeding rates would not create any competition outside the row.” In drier years Glenn will often increase the area sown to barley as it has a greater competitive ability and tends to perform better under marginal soil moisture conditions than wheat. Beefwood Farms’ consulting agronomist is Stuart Thorn, a director of MCA Ag, Goondiwindi. Stuart oversees the herbicide program for the operation, including recommendations for herbicide mixes and rotation of herbicide modes of action. “Bringing in new country into our cropping program usually involves tackling large weed populations such as a recent acquisition where barnyard grass was a big problem and we used residuals to help regain control,” says Glenn. “Residuals have also helped with feathertop Rhodes grass, and then we backed away once the problem was under control, which usually only takes a few years.” In the fallow Glenn uses a double knock of glyphosate applied as a blanket spray and then followed up with paraquat to treat any survivors using the optical sprayer. They also use glyphosate at robust rates through the spot sprayer and no longer mix glyphosate and 2,4-D. To stop weed seed set in-crop Glenn will often implement a late spray of a Group Z grass selective herbicide, flamprop-m-methyl, to patch out weedy areas of wild oats in wheat. Chickpeas are always desiccated to prepare the crop for harvest and this can have some weed control benefit going into the fallow. Picloram applied in cereals to control broadleaf weeds such as sowthistle also provides a residual effect to reduce fleabane germination in July/August. “Maintaining stubble and ground cover is our number one priority so there is no cultivation for weed control or any other purpose,” says Glenn. “Our best chance to grow competitive crops is to have stored soil moisture.” At this stage Glenn has not implemented any harvest weed seed control measures at Beefwood but he is keeping an eye on developments. Due to the loss of stubble involved, they will not adopt narrow windrow burning but other tactics that maintain and spread stubble cover would be considered if the need arose. Automation for spot spraying works well – but is now on hold Having already seen the chemical savings and the weed control benefits of using optical spraying technologies for over 10 years, Gerrit and Glenn were looking for ways to extend the value of the technology to achieve even greater efficiency with chemical use, particularly in fallows. “Gerrit has contacts with the Dutch company, Precision Makers, who had developed software for autonomous lawn mowers, and in about six months they had made the necessary modifications and installed the software on a Fendt 936 Vario tractor that we had on the farm,” says Glenn. “We found the autonomous tractor paired with the optical sprayer was a perfect fit, allowing us to spray 24 hours a day if conditions are right and to spray on the weekends without adding to our labour costs.” After a few years they purchased a John Deere 8345 tractor, also fitted with Precision Maker equipment. Over the last 10 years the optical spray operations have applied herbicide to an average 2 to 8 per cent of the field area, using robust rates, but this is still far more economical than blanket sprays. The now-decommissioned automated tractor towing a WEEDit optical sprayer. “We know it works very well when weed density is low. Now we can use the autonomous tractor to spray more frequently than you would with a driver, we have started pushing the boundaries and using the optical sprayer in paddocks with weed density of 30 per cent, knowing that we can keep coming back,” says Glenn. “Even at a higher herbicide rate this is cheaper than a blanket spray operation. The more often we go back the less large weeds there are and we are spraying smaller weeds that are easier to kill.” In a recent spray job on 3500 ha of fallow the optical sprayer activated spray nozzles on just 0.7 per cent of the area, at a cost of 24c per ha for chemical, without a driver. “Using the autonomous tractor is not about reducing our labour force,” says Glenn. “The person who used to drive the tractor is still looking after the spray job. The other job that is perfect for the autonomous tractor is tram track renovation.” Every three years, usually following chickpeas when there is less crop residue, the tractor operates a TPOS flat track renovator along the 2 to 6 km long CTF wheeltracks – saving someone from a very boring job. Having proven the value of automation to the farming system at Beefwood Farms, they have been forced to put their work in this area on hold after John Deere bought out the automated machinery component of Precision Makers in 2019 and have decided to concentrate on automated mowers for the turf industry. They are currently not servicing the automation software that Beefwood Farms had installed in two tractors. “Unfortunately, until we find a suitable alternative, we have had to go back to fully conventional operations for spraying,” says Glenn. “It is hard to accept when we have seen the benefits of automation for these routine operations.” A few years ago, Beefwood Farms bought a 48 m AgriFac self-propelled sprayer to increase their spraying capacity for blanket sprays and fallow spot spraying. The AgriFac sprayer is twice as wide at the WEEDit boom and can travel at twice the speed of the autonomous tractor, so even though there is a driver they are covering three to four times the area. Green-on-green spraying Beefwood Farms is also on the cutting edge of the latest innovation in weed detection and herbicide application, working with AgriFac and Bilberry in the testing of green-on-green spraying. Since purchasing the AgriFac SP sprayer they have been keenly observing the advances in the artificial intelligence, or machine learning, and assisting with the field testing. Beefwood Farms is working closely with Agrifac and Bilberry to bring green-on-green weed detection and spraying to reality. To work in-crop the software on the sprayer needs to interpret the images from the camera, distinguish a weed from surrounding crop plants and then identify the species and size of weed. Within moments the sprayer needs to respond and deliver the correct herbicide at the right rate to the identified weed. “The expectation is that the sprayer will be able to treat a ‘site’ of 30 cm square with exactly the right product at the right rate,” says Glenn. “This is really exciting technology and once it is fully developed we see no reason why it couldn’t be used autonomously.”
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Case Study

Kwinana East HWSC growers, WA

Having said that, growers in low rainfall areas have successfully implemented HWSC, even in cereal crops yielding 0.5 to 1.5 t/ha. In 2018, GRDC invested in the collection of ten case studies with growers from the Kwinana East port zone around Merredin, WA to discover what modifications and tactics they were using to successfully collect and destroy weed seeds at harvest in this low to mid rainfall zone. The HWSC methods these growers use are narrow windrow burning, chaff lining, chaff decks, chaff carts and impact mills. Former Planfarm agronomist, Dani Whyte, visited the growers who are all running very efficient, low cost operations to generate profits in this environment and seeing the benefits of HWSC in their farming systems. Dani Whye, former Planfarm agronomist, visited ten growers from the Kwinana East port zone around Merridin, WA to discover what modifications and tactics they were using to successfully collect and destroy weed seeds at harvest in this low to mid rainfall zone. “It is difficult to grow highly competitive crops in this region where the average rainfall range is 200 to 350 mm and the scale of operation often does not allow for high seeding rates and narrow row spacing,” she said. “This means that weeds such as ryegrass tend to have a prostrate growth habit and are generally not ‘held up’ by the crop at harvest. This results in a greater proportion of the weed seed being found closer to the ground where they can escape under the cutter bar, compared to what is typically seen in higher biomass crops.” Since having the weed seeds enter the header is the critical first step to successful harvest weed seed control the growers have focussed on reducing harvest height to 10 cm or less above ground level. Because the crop biomass is low this does not impact on harvest costs but it is all the more important to ensure the paddocks are free of rocks and other obstacles. “Along with low harvest height, many of these growers have also made minor modifications to the comb to maximise both grain and weed seed capture,” says Dani. “Sharp knives and lift kits have been shown to help gather the crop and weed seed heads onto the cutter bar in low biomass crops.” Glen Riethmuller from DPIRD, has recommended attaching coreflute to the finger tyne reel to enhance the harvesting of low yielding crops, and this may also benefit weed seed capture. The coreflute sits approximately 25 mm longer than the reel fingers and has a sweeping action to pull grain and weed heads into the header front and prevent them falling backwards off the knife. Farming a total area of around 7500 ha at Southern Cross, WA, brothers Clint and Wayne Della Bosca and their wives Jess and Dianne chose to add a chaff deck to their harvester for the 2016 harvest as part of their move into controlled traffic farming. Knowing where the weeds are has given them confidence to sow earlier and to use different herbicide options. It adds flexibility to the system. Having noticed that some weed seed heads were not entering the header front, even though he was harvesting as low as possible, Clint has fitted corflute to the reel and a narrow knife guard and extendable fingers to the header front to capture more weed seed and grain at harvest. Quick tips for harvest weed seed control in low biomass crops The most common tactics these ten grain growers used to maximise weed seed capture in low yielding or low biomass crops were to increase crop competition, make some simple modifications to the header front, cut the crop low, harvest weedy paddocks first and use their chosen form of HWSC in every paddock, every year. WeedSmart western region agronomist, Peter Newman says growers are using these tactics and seeing benefits in their weed control, but there is limited research done to validate many of these practices. “We do have strong evidence for some things though such as the impact of increasing crop competition any way you can, and cutting crops low to maximise weed seed capture,” he says. “The header front modifications are observed to work well and are generally relatively cheap for growers to trial on their machines and evaluate the benefits themselves.” 1. Crop competition Establish competitive crops by sowing early, increasing seeding rates and east-west sowing where possible. Choose competitive varieties, particularly for weedy paddocks. Reduce row spacing to ‘hold weeds up’ in the crop canopy – a move from 12” to 10” row spacing or adopting paired row sowing can increase yield, reduce weed seed set and aid harvest of both the crop and the weed seed. 2. Header front modifications Extended fingers and a narrow knife guard/ lift kit fitted to header front. Sharp knife. Narrow knife guard with plastic extension fingers to capture and hold heads on the front so they don’t fall forwards. Coreflute attached to the finger tyne reel to pull grain and weed heads into the header front and prevent them falling backwards off the knife. 3. Harvest time Choose a HWSC tactic that suits your farm. They all work well to reduce weed burden but there are differences in cost, additional work, nutrient concentration and stubble management. Number 1 tactic – harvest 10 to 15 cm off the ground. Paddocks must be clear of stumps and rocks. Harvest weedy paddocks first before weeds shed their seed or lodge. Clean down the harvester before shifting paddocks. Chaff decks (pictured), chaff carts, impact mills, chaff lining and narrow windrow burning are all being successfully implemented in the Kwinana East zone. Case study growers Cusack family, Narembeen (narrow windrow burning) Shadbolt family, Mukinbudin (narrow windrow burning) McGinnis family, Merredin (chaff line) Todd family, Dowerin (impact mill) Crane family, Kondinin (impact mill) Metcalf family, Dowerin (chaff cart) Dolton family, Bruce Rock (chaff cart) Turner family, Pingelly and East Corrigin (chaff cart) Kirby family, Beacon and Nyabing (chaff deck) Della Boscar family, Southern Cross (chaff deck) Download whole booklet Other resources Podcast – Farmers share their HWSC experiences with Planfarm agronomist, Dani Whyte AHRI Insight – Behind every successful HWSC approach is crop competition Podcast – Harvest tips, crop topping + trifluralin resistance Narrow row spacing: Is it worth going back? 
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Case Study

Stephen and Michelle Hatty, Matong NSW

The family now crops a total 2100 ha of land within an 11 km radius, on a very flat landscape with soils ranging from red loam to heavy red clay and self-mulching black clay. They adopted reduced tillage practices in the 1990s and now run a 12 m controlled traffic farming (CTF) system.   The Hatty family uses a double break crop sequence strategy of a pulse then canola, followed by wheat then barley to put firm downward pressure on the weed seed bank. The very wet season in 2016 resulted in unavoidable soil compaction and weed escapes, which prompted Stephen and Michelle to upgrade from a tyne seeder on 333 mm rows to an NDF disc seeder on 250 mm rows. The seeder has worked well from the first season onwards with dry sown crops establishing uniformly since 2017. “We had been considering the change for a while as disc seeders work well in heavy clay soils, conserve more moisture and result in much less soil disturbance,” says Stephen. “We had been finding that even though the soil structure is quite good, the tyne seeder tended to bring clods to the surface when the soil is dry at the start of the canola seeding program in April.” “It also gave us the opportunity to further increase crop competition with the narrower rows,” he says. “We also get better seedbed utilisation and can lift our planting rates to maximise yield.” Changing to a disc seeder gave the Hattys the opportunity to further increase crop competition with the narrower rows and lift their planting rates to maximise yield and optimise seedbed utilisation. The Hattys use a double break crop sequence strategy of a pulse then canola, followed by wheat then barley to put firm downward pressure on the weed seed bank. Stephen says the pulse phase of faba beans, lentils or field peas helps improve subsoil moisture and soil nitrogen for the following canola crop. Pulses offer different chemistry options for grass weeds and even brown manuring if weed pressure is high. “For example, trifluralin is normally out for cereals but can be used after a pulse crop like faba beans that doesn’t leave much cover on the paddock,” he says. “We also use water rates of 80 to 100 L/ha to maximise the effectiveness of pre-emergent herbicides in high stubble situations.” The Hattys are keen to host trials on their property where they are able to see first-hand the outcome of different agronomic options or crop performance. In 2017, they hosted NSW DPI trials looking at the competitive ability of Planet and La Trobe barley, with Planet being more prostrate in growth habit and La Trobe being very upright. In 2017, they hosted NSW DPI trials looking at the competitive ability of Planet and La Trobe barley, with Planet being more prostrate in growth habit and La Trobe being very upright. “We sow all our crops early in their optimal sowing windows and try to take advantage of more competitive varieties to suppress weed growth,” says Stephen. “In dry conditions barley is a great option to reduce weeds, produce significantly higher grain yield and return more straw than wheat ahead of sowing a pulse crop.” In 2015 the Hattys added harvest weed seed control to the program. They chose to fit an Emar chaff deck system to their Case 8230 header and have been confining weed seed to the 3 m tramlines ever since. Since adding an Emar chaff deck system to their Case 8230 header in 2015 the Hattys have slowed down the chaff deck conveyors and added a chopper to improve straw spreading. “We have slowed down the chaff deck conveyors and added a chopper to improve straw spreading,” says Stephen. “We had already been harvesting fairly low to suit the tyne seeder so there was no real change to the way we harvest. As time goes on we expect that less and less weed seed will be deposited each harvest resulting in fewer and fewer weeds growing on the tramlines.”
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Case Study

Day family, Lockhart NSW

Mark and Steven Day run Woodlea Ag Enterprises in conjunction with their father Max, with the backing and support of their wives and families in the decision making process. The continuous cropping operation at Lockhart, NSW is based on a zero till, 12 m controlled traffic system on 3 m wheeltracks and using an NDF disc seeder. Returning to the farm in the 2000s after completing their tertiary studies, Mark and Steven have developed a farming system that uses new technologies and capitalises on well-worn rotational farming concepts.   Mark Day, and his brother Steven, run a highly efficient cropping rotation on their family farm at Lockhart, NSW. In 2009 the Days noticed that weed pressure was building and they were concerned that the weed seed bank would soon be unmanageable in their canola-wheat-wheat rotation. “We took the advice of our agronomist and decided to introduce a legume brown manure phase,” said Mark. “Our first choice was field pea because they are the most competitive legume option and provide a good level of ground cover and biomass. In recent years we have also grown vetch, lupins and faba beans to avoid disease build-up in field peas.” Over the last 10 years the Days have settled into a stable double break rotation, which has been a key strategy to keep weed numbers low in their cropping operation, and they have also introduced chaff decks for the last three harvests for weed seed management. Key developments Pre-2009 – CTF, continuous cropping canola, wheat, wheat and variable rate technology (for lime and gypsum prescriptions and P replacement) 2009 – legume brown manure introduced in response to increasing weed pressure 2012 – NDF seeder and full stubble retention 2016 – chaff deck for HWSC across whole farm Grid sampling for pH and replacement phosphorus has led to variable rate lime, gypsum and P applications. Crop rotation “We start with the brown manure legume followed by TT canola, then a double cereal phase of wheat and barley,” he said. “This sequence allows for optimal use of herbicides within the stubble retention system and we can rotate a range of herbicides.” Double break – brown manure legume then TT canola. Double cereal – wheat then barley. “Herbicide rotation and double knocking to protect glyphosate is keeping a wide range of herbicides effective and we take advantage of the differences in stubble load to use each product in the most effective way,” he said. “For example, we apply Sakura when planting wheat following canola crop and the stubble load is not excessive, allowing the Sakura to work well.” The legume brown manure followed by canola gives Mark and Steven the opportunity to use a range of herbicide tactics, including rotating propyzamide, atrazine and clethodim, to drive down grass and broadleaf weed numbers. They also occasionally apply grass selective herbicide over the top before brown manuring if required. The manure crop also helps retain soil moisture and maintain a baseline of nitrogen in their system. Adding stubble retention also contributes to soil moisture and nutrient conservation, but the crop sequence is key to making the NDF disc seeding system work well. “Our rotation is set up so canola is established in a low residue situation after the brown manure, wheat is established into canola stubble and the brown manure pulses are sown into high crop residue situation after the cereals using a deeper disc setting,” said Mark. When it comes to managing weeds through the rotation, the legume is brown manured using a traditional glyphosate paraquat double knock following a roller to achieve better spray coverage of weeds low in the canopy. The double knock is also applied prior to seeding. Tillage is used on about five per cent of the cropped area each year in response to specific situations such as providing a triple knock of the brown manure crop, for restoration of wheeltracks and headlands and to incorporate lime or address nutrient stratification. Strategic cultivation also enables the effective use of trifluralin in the disc seeding system. Cultivation provides the third knock at the end of the legume crop whenever there is a dual purpose for the tillage (e.g. wheeltrack renovation or stubble management). In-crop strategies include increasing seeding rates in weedy or high pressure areas using variable rate technology, spraying under the cutter bar when windrowing canola and crop-topping feed barley at the end of the rotation. Harvest weed seed control – Chaff decks Even though the system was humming along well, the extreme wet conditions in 2016 led to significant weed escapes, prompting the Days to look into harvest weed seed control. Having seen the benefits of the chaff deck system, Mark and Steven bought one for their own harvester and worked with their contractor, Warwick and Di Holding, to have one fitted to the harvester that operates on their property. Chaff decks have proven their worth for harvest weed seed control. “At first we had to convince ourselves that the weeds really were coming off the sieves and we were amazed just how much is collected and deposited on the wheeltracks when the harvester is set up correctly,” said Mark. “The whole farm is now treated with the chaff deck for harvest weed seed control, every year. The weeds are confined to a manageable and defined area. Other benefits include the reduction in dust over summer and we can easily assess harvest losses.” There have also been a few downsides to the chaff deck system that need to be worked around, such as stubble lumps on wheeltracks and the potential for nutrient redistribution to the wheeltracks over time. “We have seen poor establishment in some situations and certainly black oats can evade all harvest weed seed control tactics as the seed has already shed by harvest time,” he said. “Windrowing barley may be a worthwhile method to address this problem.” The Days expect to move to an impact mill for HWSC in time.
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Case Study

Mark Branson, Stockport SA

Since 2017, precision agriculture enthusiast Mark Branson has been hunting herbicide resistant weeds using a DJI Phantom drone. Flying at a height of 75 to 90 m across a 46 ha paddock, the drone takes 500 images that are later ‘stitched together’ to give one image of the field. “It is as simple as ‘where you can see the rows, there’s no weeds’ and ‘where you can’t see defined rows, that’s a weedy patch’,” says Mark. “When you add an NRG filter you can clearly see the extra biomass that results from weed growth.” Mark (right) and Sam Branson use their drone to identify and map weedy areas in crop on their mixed farming operation at Stockport, SA. (Photo: Vanessa Binks) Once patches are mapped and ground-truthed to check the species present, Mark then decides on the most appropriate course of action. In the last three years he has cut five patches of about 10 ha each for hay using a cutter bar mounted on the SP sprayer. The main resistant weeds on the farm are annual ryegrass, wild oats and wild radish. Although it is easy to see the wild radish present in wheat crops the grasses are hard to see from the ground, and it is difficult to accurately map weedy patches. The idea of using a drone to scout for weeds was sparked in 2015 when Mark’s son Sam bought a drone with a GoPro camera attached to gather video footage. Mark could see the possible application in precision agriculture and in 2016 he bought DGI Phantom 4 to look down into crops. One of the first ‘jobs’ the drone did was to identify an area of poor urea application in a crop. “The real advantage in identifying the mistake in-crop was that we had the opportunity to take remedial action and fix the problem with an application of liquid nitrogen in the affected area,” says Mark. “Without the drone that mistake would have gone un-noticed and we would have suffered a yield loss in that portion of the paddock.” When it comes to hunting for resistant weeds, Mark first traces the boundary of the paddock in the drone software package and then, with a set flying height and number of images to collect, the drone takes off and takes the required set on images. The advantages of the drone imagery over satellite images include being able to collect and use images collected on cloudy days and having full control over the timing of the data collection. The drone is also better suited to the job than the tractor-mounted biomass sensors that can only collect data from a 40 m swathe at a time. For the drone image capture to be successful it is necessary to have stable light conditions. “It is fine to fly on both clear and cloudy days, provided the conditions don’t change for the duration of the 20 min flight time,” says Mark. “It is best to fly between 9.30 am and 4 pm to reduce the impact of shadows and I generally prefer cloudy days.” One of the few advantages of the tractor-mounted biomass sensors over the drone is the ability to collect data at night. Mark spent a few thousand dollars on his drone but as prices continue to drop, he says a suitable drone can be bought for $1500 or less. He uses a third-party provider, Drone Deploy, to process the images collected into the one seamless image for an annual cost of US990. “The Drone Deploy subscription is expensive but the quality of the image stitching is excellent and the turn-around is fast,” he says. “It only takes 3 or 4 hours for a set of images to be stitched and returned.” Using an NRG filter it is possible to clearly see the extra biomass that results from weed growth in-crop. Mark has three batteries for the drone, each having a flight time of 20 minutes, which means he can easily fly any of his paddocks in a day. He advises any new pilots to be conscious of no-fly zones and to comply with licencing requirements. “The drone has certainly proved its worth as a good tool for scouting and for identifying and mapping suspicious areas that need investigation and diagnosis,” he says. “I am also working to find an index that will reliably show frost damage.” Mark and his son Sam crop 1200 ha of wheat, barley, peas, beans, canola, lentils, oats. In November 2015 the catastrophic Pinery fire severely impacted the Branson’s property, destroying crops, machinery and livestock, and they were very fortunate that the fire leapt over their home, leaving it unscathed. Prior to the fire the Bransons ran a self-replacing merino flock of 1000 ewes, three-quarters of which were lost in the fire. They have now built back up to 850 ewes. Mark was a founding committee member of the Society of Precision Agriculture Australia (SPAA) in 2002 and completed a Nuffield Scholarship in 2005, looking into the economic and environmental impacts of precision agriculture and conservation farming in New Zealand, USA, Canada, UK and France. “I started marrying up wheeltrack widths in 2002, and then bought a tractor with an RTK steer kit in 2004,” says Mark. “The Nuffield Scholarship confirmed a lot of existing knowledge and understanding, and gave me new direction and confidence to apply precision agriculture to our farm operation. Since then we have used variable rate technology particularly for nutrient management – gypsum, lime, N and P – and seeding rate.” The Stockport area has suffered two very dry seasons, receiving just 3 per cent of their average growing season rainfall 2018, a less than 1 percentile year. Conditions were very similar in 2019. Big 6 in action on Branson Farms The Bransons run a winter cropping rotation and sheep are an important part of weed control program, with the pasture phase being key to driving down annual ryegrass numbers. They have implemented a wide range of tactics from the WeedSmart Big 6. 1. Rotate crops and pastures The Bransons run a winter cropping rotation and sheep are an important part of weed control program, with the pasture phase being key to driving down annual ryegrass numbers. The crop sequence Mark uses is pasture, canola, wheat, wheat, barley, grain legume, hard or durum wheat (high protein), wheat, [or canola if weeds are building], wheat, wheat, barley, grain legume and back to pasture. The pasture phase is a minimum of two years and preferably three years to ensure all the ryegrass has germinated before returning to cropping. Within the cropping phase Mark includes a cereal with resistance to cereal cyst nematode (CCN) and no longer uses imi chemistry or imi-tolerant crops due to resistance in ryegrass. TT canola is still a useful strategy for ryegrass control. The pasture or ley phase is based on cereals mixed with either medic (on alkaline soils) or sub-clover (on acidic soils). Mark’s father used the same system, based on soil colour, but now Mark has the two mixes in the seeder box ready for VR application according to the PA maps from pH surveys. Mark also uses the sheep to graze crop stubble at high density for a short time after harvest. The sheep benefit from the stubble and graze any weeds present. Although their hooves compact the surface of the soil the layer is easily broken up at seeding. 2. Mix and rotate herbicides Mark is very aware of herbicide resistance and the need to rotate between mode of action groups. He does not routinely conduct herbicide resistance testing but he is careful to observe any changes in herbicide efficacy. For example, he witnessed one wild oats plant escape Topik (Group A herbicide) and how rapidly this escalated to a patch of herbicide resistant weeds. He looks for ways to use a range of herbicide options across the cropping phase to control wild radish. Likewise, there are several pre-emergent herbicides used such as simazine in beans, triazine in canola and Sakura in cereals, keeping in mind that the triazine and Sakura need to be applied in seasons where there the likelihood of them being washed off the stubble and into the soil is high. 3. Crop competition Mark chooses competitive wheats, such as Saintly, and follow them with Scope barley, which is a vigourous variety that provides good early competition. Although he prioritises competitive attributes over extra yield he says that all the varieties are quite good for yield. The Bransons have been direct drilling since 2002 and currently use a tyned precision seeder that places the seed one inch apart in a parallelogram configuration. The tynes have individual depth control and presswheels. Mark currently sows crops in 10 inch rows but he would prefer 6 to 9 inch row spacing, which is not practical with his current tyne seeder. He will probably move to a disc seeder to reduce soil disturbance when he is ready to upgrade. The seeder allows inter-row sowing, which Mark says is the key to stubble management. Currently the rows are 10 inches apart but Mark would prefer 6 to 9 inch row spacing, which is not practical with his current seeder. He will probably move to a disc seeder to reduce soil disturbance when he is ready to upgrade. Mark uses VRT seeding and nitrogen application for canopy management to ensure enough moisture is available at the end of the season for the crops to finish strongly. 4. Stop seed set Mark uses both mechanical and herbicide tactics to stop escape weeds setting seed. In the pasture phase, Mark slashes and grazes to prevent seed set and pasture tops with paraquat. He uses crop topping in pulses and in triazine tolerant canola he sprays glyphosate under the cutter bar, then harvests the windrows and drops crop residue into a narrow windrow for burning. This tactic in canola is an excellent way to really drive down ryegrass numbers in a single year. Mark implements this in the first year out of pasture and also within the cropping phase to extend the length of the cropping phase out to 10 to 12 years. Prior to getting weed numbers down, the cropping phase was only 6 years. He finds that hay is a good way to deal with weedy patches. So far, he has successfully used hay making to deal with two patches of herbicide resistant weeds identified using the drone. He says wild oats soon becomes a long-term project if it gets out of hand so he’d much rather accept a short-term sacrifice. 5. Double knock If there is an early break to the season Mark usually implements the double knock pre-seeding. After harvest, the sheep can also provide the first knock on weeds, which are then sprayed out by 5-leaf stage. He doesn’t usually do a second spray for summer weeds but finds that the sheep do a good job of cleaning up any weeds that survive any herbicide treatment. 6. Harvest Weed Seed Control Mark has seen the benefits of narrow windrow burning in canola and plans to have an impact mill within the next five years. He hopes that having an impact mill on the harvester for all crops will take the pressure off some of the other practices currently used.
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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)
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Case Study

Tim Rethus, Horsham Vic

Tim Rethus and his brother Luke farm with their father Geoff and workers Glenn and Dale in the central and southern Wimmera, where they are contending with Wimmera annual ryegrass, brome, wild oats, vetch, bifora, sow thistle and prickly lettuce. “Our approach to weed control centres on keeping weed germination levels low and using diverse farming practices,” says Tim. “Dad was an early adoptor of minimum tillage back in the early 1980s and we have progressively moved to farming systems that involve less and less disturbance. One of the major benefits is that we are leaving the weed seeds on the soil surface where they are exposed to the weather and don’t have the soil contact they need, and this really reduces weed seed germination.” Wimmera grower Tim Rethus and his family are taking an integrated approach to the weed management with a strong focus on weed-free crops. A key element to the Rethus’ success is their determination to achieve near-zero disturbance at planting. When they adopted a 40-foot CTF system in 2008 their min-till single disc seeder did a good job and reduced soil throw but ten years on, the removal of machinery traffic from the cropping zone had led to the single discs often stalling in the softer soil and the depth control was no longer adequate. This led the Rethus’ to invest in a zero-till precision planter to provide more precision at planting, including inter-row sowing for lentils, and to make best use of the newest chemistry available. The planter the family has built with minimal soil disturbance in mind, to reduce weed germination at sowing. “This precision seeder was a good unit but it was complex and didn’t suit all our crops,” says Tim. “So, we decided to combine the precision row units with twin-disc openers on a new 80-foot NDF frame but use an air-seeder to deliver the seed.” To further reduce soil throw, residue managers are not used. Instead ‘PTT Sabre-tooth’ discs are used to cut through the residue and reduce pinning. The two discs are slightly different in size, so they rotate at slightly different speeds, providing a cutting action to keep residue out of the seeding furrow. “Adding side-shifting rams to the toolbar means we can also inter-row sow our lentils and we have a seeder that meets all our requirements, especially in terms of maintaining low weed seed germination at seeding while still sowing at 15-inch row spacing.” The seeder also has moisture sensors along it that are linked to the depth control of each individual row to try and put all of the seed in the same level of moisture, ensuring an even strike. Zero disturbance planting in CTF beds is working a treat to minimise weed seed germination. The Rethus family practice a diverse crop rotation of wheat, barley, durum, canola, lentils, beans and oats, and use shielded spraying, hay production, brown manuring, spray topping and diverse herbicide strategies to minimise weed seed set. Tim says the reality of herbicide resistance means non-chemical tools are very important to maintain low weed numbers and this is one of the driving forces behind their efforts to fully integrate hay production into their CTF system. “Within the rotation we usually have about 35 to 45 per cent legumes for their soil health benefits and the additional herbicide options available,” he says. “We practice chemical double-knock and mix and rotate our chemistry, realising that herbicide resistance is inevitable but we can delay onset and do all we can to maintain low weed numbers.” The Rethus’ herbicide program starts with a pre-sowing double-knock where the pre-emergent is mixed with the paraquat if the season permits. They aim to apply the pre-emergent as close to crop emergence as possible so very little of the active life of the herbicide is wasted, this is particularly important when dry sowing so they delay application of the pre-emergent until breaking rains fall. They mix and rotate pre-emergents where possible and are careful when planting two cereal crops in a row to not use Sakura both times, favouring Boxer Gold for barley crops. Legumes offer a number of Group C options to rotate between and in oaten hay they have found Dual Gold and diuron is a good mix provided care is taken to use the correct rate for different soil types. The mobile chemical storage and mixing truck the family uses to ensure their herbicides are mixed and applied safely and effectively. In-crop they use multiple modes of action where possible, with legumes presenting serious limitations for in-crop broadleaf weed control due to the limited products available. At the end of the season cover crops are terminated using multiple modes of action and a double-knock and lentils, canola, and sometimes barley, are crop-topped. The Rethus’ routinely test weeds for susceptibility to the herbicides used across the cropping program to ensure they are using effective products and mixes. They use either a quick test in season or seed test at harvest if there are unusual weed escapes. To avoid producing herbicide resistant weeds along the farm’s roadsides and tracks the Rethus’ choose to mow, rather than spray, the vegetation growing there. For the last 15 years hay production has been an important mechanical control method to stop weed seed set – particularly for annual ryegrass. The Rethus’ will do up to three years of hay production in a row to drive down the ryegrass seed bank before returning to the grain cropping rotation. “We run a controlled traffic operation and that makes hay production challenging,” says Tim. “Over the years we have developed systems and machinery that make it possible to keep to the wheeltracks throughout the hay-making process.” “We use a front-mounted and side-mounted mower/conditioner to make three small windrows per CTF pass. The three windrows across the 40 ft CTF run are then raked together ahead of the baler. This provides a solid, constant feed into the baler travelling along the CTF wheeltracks, from crops that produce a biomass of typically 7 to 8 t/ha.” “The final trick is to move the bales from the centre of the wheeltracks to the side so they can be picked up by the stacker. Our uncle built a hydraulic lifter that is mounted on the front of the tractor and simply lifts each bale and places it to the side where it is picked up by the stacker running behind the tractor. We stack all the bales at one end of the paddock making it easy for the telehandler operator and truck drivers,” he says. “We can bale, stack and store 600 bales a day this way without running off the CTF wheeltracks.” The camera guided shielded sprayer is used to target vetch in lentils to avoid grain contamination. In-crop, the Rethus’ use a camera-guided shielded sprayer for inter-row spraying in lentils. The Crop Stalker recognises the crop rows and follows between them, not relying on the crop to guide the shields. Crop rotation is also used to manage persistent hard-seeded weeds, such as seven years without lentils for vetch control and four years without barley for wild oats control. Tim has found that even when they leave out their most profitable crop, lentils, for an extended period the paddock can remain very profitable. “Another strategy we use for stopping seed set is to include multiple termination dates in the rotation, so the crop-topping, brown manuring and hay cutting all happen at different times,” says Tim. “Adding another layer of diversity reduces the selection for early maturity in weeds.” Vetch has long been the brown manure used to build soil health but the Rethus’ are now using a multi-species cover crop for even better soil outcomes and reducing the build-up of vetch seed, which is a persistent weed in their system. When it comes to crop competition the Rethus’ CTF system is set up for 38 cm (15 inch) row spacing, so they look for other ways to increase the crop’s competitive advantage. Starting with clean seed, their highest priority is minimal soil disturbance at sowing and maintaining standing stubble throughout the rotation. With the seeder only disturbing a very narrow band of soil there is little stimulation of weed seeds to germinate between the rows. “We also sow early to take advantage of warm soils for maximum early growth and choose competitive varieties such as RGT Planet barley, Jumbo II lentils and hybrid canola,” says Tim. “It is very important that the crops we grow reach canopy closure by the time the pre-emergents have run out, and investing in good crop nutrition to support high biomass production in good years pays off.” Choosing competitive crops and varieties is a very deliberate weed control strategy used. Tim and Luke are avid adoptors of new precision agriculture tools to map weeds, in-crop green-on-green spot spraying with best chemical rates to target persistent weeds like vetch, bifora, wild oats and brome and spot spraying summer weeds to reduce chemical use. The Rethus’ robust integrated weed management system incorporates all of the WeedSmart Big 6 tactics except harvest weed seed control. With their focus on multiple in-crop strategies to minimise weed germination and seed set they find that their crops are almost weed-free at harvest.
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Case Study

Brad Jackson, Gurley NSW

Weeds are not yield-reducing on the Jackson family farms at Gurley, in northern NSW, and that’s how they want to keep it. Brad Jackson farms ‘Bellaree’, ‘Jymoomah’ and ‘Inverness’ with his parents Peter and Janice, and brothers Phil and Matt. The 1700 ha family operation is based on a robust winter cropping program featuring wheat, barley, chickpea, canola and linseed to help keep weed numbers low and manage risk. Brad Jackson, Gurley NSW Each year there is wheat on about 30–40 per cent of the farmed area and several break crops. If weed numbers start building up in a paddock they use a canola–chickpea double break to help drive down the weed seed bank. “We see annual ryegrass coming – it’s in the district and on our farm,” says Brad. “We know how bad it can get and how quickly herbicide resistant populations develop. We want to stay on the front foot.” Having focussed on winter cropping in recent years the Jacksons, like most in NSW’s north, have been battling low rainfall for several seasons in a row. 2015 was the start of the long dry stretch and the challenges in 2016 were softened slightly with better results from some crops than expected, but it was also a year the family worked hard to manage expectations and take mental health seriously. 2017 and 2018 have been record dry years in the district where the Jacksons have been lucky to harvest their crops. “We are heading into the 2019 winter with a completely dry soil profile, which is unheard of in living memory for this district. We have decided to ‘plant anyway’ and hope for the best,” says Brad. “In the end we usually end up with crops to harvest even though the yields have not been great. This year we desperately need ground cover so even if we don’t harvest grain we really need to invest in planting.” In a string of very dry years, the Jacksons have planted their winter program and ‘hoped for the best’. The Boss precision planter with coulters on a parallelogram configuration allows better trash flow and they have more control over the planting depth. Last season they were rewarded with a chickpea crop establishing well from a planting depth of 20 cm. “The rotation that has worked well here is wheat, followed by canola, then barley, then linseed. Linseed can dry out the profile but is important in the rotation to control root-lesion nematodes,” he says. “We don’t grow any summer crops so we use multiple tactics in our winter crops to keep weed numbers low.” The Jacksons also grow grazing oats for seed production under contract so keeping the farms as weed-free as possible is very important. Having used a conventional tined precision planter for the last 15–20 years, the Jacksons are now using a Boss precision planter with coulters on a parallelogram configuration. They are finding the trash flow is better with the coulter and they have more control over the planting depth. Last season they were rewarded with a chickpea crop establishing well from a planting depth of 20 cm. Brad and Peter attended the 2017 WeedSmart Week in Wagga Wagga where they were convinced of the need to reintroduce the use of pre-emergent herbicides and take every opportunity to mix and rotate herbicide modes of action. The Jacksons also use strategic tillage, optical sprayer technology and harvest weed seed control to reduce the risk of herbicide resistance in weeds. In the last few years they have introduced desiccation in chickpeas and crop-topping in canola to control late winter grasses and early summer grasses. Re-introducing pre-emergent herbicides In 2018 the Jacksons applied pre-emergent herbicides across 70 per cent of the farm, for the first time in 20 or 30 years. Their aim was to implement another tactic to control ryegrass, phalaris and black oats using pre-emergent applications of treflan and Avadex in linseed crops and treflan and Boxer Gold in wheat and chickpea. In the linseed and chickpeas they apply Verdict and Select in-crop. Linseed provides multiple benefits to the Jackson’s rotation. Unlike many other growers in their area the Jacksons have chosen to grow only winter crops and so need to use several tactics to ensure sustainable weed control. The seasonal conditions did not favour high efficacy in pre-emergent chemistry but the Jacksons found that they achieved better crop establishment with the coulter than would have been possible with their old planter, providing good support for the applied herbicides. Optical sprayer The Jackson’s WEEDit optical sprayer has revolutionised their herbicide program, allowing them to spray low weed density paddocks more frequently and target small, fresh seedlings. They also use it to provide a second knock following a broadacre spray on paddocks with high weed numbers. They are finding this to be a great way to reduce their reliance on glyphosate and ensure this useful chemistry is still effective in the future. “Optical sprayer units are fairly common in this district,” says Brad. “We purchased ours in 2016 mainly to manage herbicide resistance. We couldn’t really justify the investment based on herbicide savings alone.” The WEEDit optical sprayer has widened the herbicide options available to the Jacksons in summer. “The desiccation or crop-topping operation is the start of our summer weed control program. After rain we use the broadacre sprayer to apply glyphosate plus a Group A fallow pre-emergent and then double knock with paraquat using the WEEDit,” he says. “It is important to start early to target barnyard grass and we are able to spray more often and target small weeds every 3 to 4 weeks if necessary with the WEEDit. The main summer weeds here are feathertop Rhodes grass, barnyard grass, and button grass.” The Jacksons expect to see a reduction in herbicide costs over time through the use of the WEEDit but at the moment they are using it to apply more expensive herbicides that would be uneconomical to apply with a broadacre sprayer to control barnyard grass. Strategic tillage The Jacksons started no-till in 1990, retaining stubble for improved soil moisture infiltration and retention, and to reduce erosion on their black self-mulching clays. Although they are committed to no-till farming there is a place for strategic use of shallow cultivation with a Kelly chain. In March 2018 they used a Kelly chain on half the farm area to kill small weeds and close the cracks that were allowing the soil to dry out at depth. “We used the Kelly chain after harvesting chickpea and then planted imi-tolerant canola 10 cm deep. The canola went on to yield 1.2–2.2 t/ha, which was a great result given the season,” says Brad. Harvest weed seed control The Jacksons started harvest weed seed control in response to the unwelcome arrival of annual ryegrass. Most years they implement narrow windrow burning on about 10 per cent of their farmed area. “We try to burn as early as possible to get hot fires – usually in February if the season allows and it’s possible to get a permit,” says Brad. “Going early also means our Big N application program can go ahead uninterrupted from December to February without running over the windrows.” The Jacksons use a 700 mm narrow windrow chute and select paddocks based on weed pressure and crop type. They delay harvest until crop straw is fully dry and plan ahead for an extra header if necessary to cover the area. This allows for the harvester operator to go slower and cut the crop low to make sure the maximum number of weed seed heads enter the front of the header. “If the windrow is too big there is potential for it to be blown over. To avoid that, we turn the chopper fins backwards on our New Holland harvester to make the windrow with the chopper when necessary,” he says. “This condenses the windrow substantially, keeping it knee high rather than waist high.” Narrow windrow burning is implemented each year on about 10 per cent of the Jackson’s cropping area. They use a 700 mm narrow windrow chute and select paddocks based on weed pressure and crop type. Care is needed when doing this as the header can become blocked up, and air from the fan can blow some weed seed out to the side and away from the windrow. Brad says the key is to get the weed seeds in the front of the header and then to ensure they are concentrated into a zone where they can be managed strategically. In terms of crop choice, the Jacksons find narrow windrow burning is a good option for wheat and barley provided the stubble load is not too high. It also works well for chickpea, faba bean and linseed because of the low harvest height and lower stubble loads of these crops, however it can be hard to achieve an even flow of material into the narrow windrow. The Jacksons generally do not use narrow windrow burning in canola crops and so opt for crop-topping as their main tactic to control weeds present at harvest. While narrow windrow burning has been an effective in containing the risk of herbicide resistant weeds, the Jacksons are keenly assessing other options such as a weed impact mill, chaff lining or tramlining to avoid the need for burning and to retain more stubble in situ.
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Case Study

Trevor Syme, Bolgart WA

A few years ago they began an extensive liming and clay delving and spading program across 50 per cent of the 3500 ha cropping area to improve the water holding capacity of the natural non-wetting sands. With 75 per cent of the affected area now treated Trevor is looking forward to having this expensive but very beneficial operation behind him. Treating the non-wetting soils has assisted with weed control through 40 per cent higher yielding crops, more even crop germination and better efficacy with the pre-emergent herbicides. “Treating the non-wetting soils has assisted with weed control through 40 per cent higher yielding crops, more even crop germination and better efficacy with the pre-emergent herbicides,” says Trevor. “It has also enabled us to grow canola in paddocks that were previously not an option and crops seem to finish better and are less prone to frosting.” They have also achieved good results building soil organic matter with brown manured cereal rye crops. Trevor has trialled summer crop brown manuring too but the results over three seasons were unreliable and he has decided to look for other options to reduce evaporation over summer and reduce the need for summer weed control. The Symes’ farming system is 100 per cent controlled traffic and stubble retention with a long winter crop rotation of lupins, wheat, canola, wheat, barley, with brown manured cereal rye grown on the soils not suited to canola. Information on the summer fallow spray program The summer fallow spray program involves 2,4-D ester, triclopyr and glyphosate to control melons, caltrop, fleabane, sowthistle and volunteer cereals. For the last 5–6 years Trevor has applied a double knock of glyphosate followed with paraquat in preparation for sowing. “We try hard to get the timing right and target the right size weeds with the double knock,” he says. “We also avoid mixing a pre-emergent in with the paraquat because the aim is to get the paraquat on weed leaves using a high water rate and fine droplet size, whereas the aim with the pre-emergent is to achieve even coverage of the soil. Doing the pre-emergent spray separately costs us more but I believe it is worth using the right boom set up for the two jobs.” “Rotating crops and herbicide modes of action, and using the double knock tactic, are critical to our weed management program,” he says. “RR canola, Clearfield barley and lupins all have a fit in the crop rotation and allow us to rotate herbicides effectively. The imi-tolerant barley has enabled quite effective control of brome grass and we croptop the canola with glyphosate.In the lupins we are using a pre-emergent propyzamide application followed with clethodim in-crop and finish with a croptopping spray of paraquat.” Trevor is finding that weed control in the lupin phase is more critical than it used to be, but the value of lupins in boosting yields in the following wheat crop motivates him to look after the lupin crops, plant into clean paddocks and do everything he can to keep weed numbers low. The Symes have had good success with high biomass canola on sandy soils where multiple germinations of wild radish are the norm. They usually plan their crop and herbicide program with their agronomist at the end of September and then revise it in February or March. Trevor is going away from the current move toward narrow row spacing and disc seeders. “We are changing back from a disc seeder at 305 mm spacing to tines on 381 mm with a split boot to sow cereals in paired rows and canola and lupin in single rows,” he says. “We are working on the idea that less rows equals less disturbance equals less weeds in a controlled traffic system. The slightly wider row spacing also makes it easier to handle the stubble load accumulated over several years and allows us to inter-row sow.” He has found that high tillering wheat varieties, such as Magenta, offer an alternative way to increase crop competition through additional shading of the inter-row. In the 2015 harvest the Symes added a chaff deck to their weed control progam, directing all the chaff, and weed seeds, into the harvester wheel tracks. Trevor harvests weedy paddocks first to maximise the value of harvest weed seed control and has found the chaff deck easy to use and results in relatively few weeds surviving in the tramlines. The biggest benefit of the chaff deck is that weed seeds are collected across the whole farm every year, and concentrated in the inhospitable tramlines. “The biggest benefit is that we can collect weed seed across the whole farm every year where previously we have only really been able to do narrow windrow burning in the canola phase. Now at harvest the whole job is done, with no need to return to burn.” “It is great to know where the weeds are and they are dumped on a hard, inhospitable surface,” he says. “Any escapes are easily collected at the next harvest. We also have a back-up plan to use a shielded sprayer to weeds in the tramlines, but we really want to avoid using this option.” “In fields with high weed numbers in the tramlines we have tried simply driving a tractor, without any implement, along every tramline to achieve a crimp-rolling effect. This seems to have been a cost-effective way to stop seed set in weedy tramlines.” In fields with high weed numbers in the tramlines Trevor has tried simply driving a tractor, without any implement, along every tramline to achieve a crimp-rolling effect (right). Annual ryegrass, wild radish and brome grass are the main weed challenges on the Symes’ property. Trevor has done some herbicide resistance testing but generally takes the approach that all weeds present are likely to have some level of resistance. “The key is to keep weed numbers low so we take care to spray when weeds are small and avoid frost windows and high temperatures when the sprays are less effective,” he says. “We also use quite high water rates – 80 L/ha for most post-emergent herbicides and 120 L/ha for pre-emergent herbicides and paraquat – and have two sprayers so we can cover as much ground as possible when the conditions are right.” “Fencelines and fire breaks are a weak point in our farming system as a source of glyphosate resistant weeds,” he says. “We have removed as many fences as possible, now that we don’t run any livestock, and are actively looking for an alternative herbicide that is not used in crop to manage weeds on the firebreaks.” Trevor takes considerable care when choosing seed production paddocks, ensuring weed numbers are low to start with and then treating the paddock as a nursery. He harvests the seed crops early and cleans the seed prior to planting.
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Case Study

Lance Wise, Bowenville, Qld

Lance and Fallon Wise and Lance’s parents, Murray and Janette crop 1600 ha and run cattle on 45 ha of non-arable rocky ridges. The locality and soft black plains enable the Wises to grow a range of crops including sorghum, mungbean, chickpea, barley and wheat, along with the occasional crop of faba bean, millet and canola. In an effort to reduce their reliance on glyphosate and overcome some of the disadvantages of long-term no-till farming, the Wises have reintroduced light cultivation and are moving toward more targeted application of glyphosate and other herbicide products using an optical sprayer. “Our usual rotation is a legume followed by a cereal, such as mungbean, to sorghum and chickpea to wheat or barley,” says Lance. “We use either a short fallow or double crop to change from a winter to summer crop program and aim for at least one crop every 12 months from each paddock.” Having been no-till farming for 25 years the Wises have seen the weeds transition to those species that proliferate in the absence of cultivation; weeds like fleabane, urochloa, feather top Rhodes grass, cow vine and bladder ketmia. In an effort to reduce their reliance on glyphosate and overcome some of the disadvantages of long-term no-till farming, the Wises have reintroduced light cultivation and are moving toward more targeted application of glyphosate and other herbicide products using an optical sprayer. Nine years ago they had success using the Kelly disc chain to manage urochloa on their less well-structured red earth soils. More recently they have used this implement to target herbicide tolerant feathertop Rhodes grass and fleabane on their main black clay soils. “We are using a chemical / tillage double knock to good effect on feathertop Rhodes grass in the fallow,” says Lance. “We apply glyphosate and then follow up five days later with the Kelly chain, which does a terrific job of pulling out sick, dead and small plants at an operation speed of 11 to 12.5 km/hr.” “The same system works well on fleabane too, pulling up plants with foot-long roots from soft soil, although a higher rate of glyphosate is required. It doesn’t work well for weeds like prairie grass that have deep, fibrous root systems.” The Wises have found the chemical / tillage double knock to work well on feathertop Rhodes grass and fleabane. Used in reverse order, Lance has found the light cultivation is an effective way to stimulate germination after a poor sorghum crop to sprout volunteers and then spray out the crop. Along with the benefits of partial stubble incorporation on soil microbial activity and ease of sowing, Lance says the two short chains in the middle fill in the 3 m wheel track to even out the paddock, avoiding the need to do extra wheeltrack renovation operations. About the Kelly chain “We also use the Kelly chain to incorporate pre-emergent herbicide after sowing to a maximum depth of 2 cm. This does not disturb seed, which is all sown at least 4 cm deep with a presswheel, and the soil is moved sideways without destroying the cracks in the soil or drying out the profile,” he says. “Weed seed is not buried deeply so it doesn’t come back to haunt you years later.” Lance avoids using the Kelly chain more than once in a season on the red soils, which can get very dusty and are prone to hardsetting on the surface. At the end of harvest Lance and Murray assess the stubble load and weed pressure in each paddock. They usually spray glyphosate after a rain event and either double knock with the Kelly chain or spray paraquat through their Weedseeker optical sprayer. After using the Kelly chain, Lance follows 30–45 days later with the Weedseeker rig to clean up any survivors. “The Weedseeker is a new fallow option for us and means that we can treat weeds that we might otherwise ignore, apply higher rates, and use more expensive products to control small areas or patches of weeds,” says Lance. “The 36.6 m boom carries 96 sensors so there are not many weeds that go undetected in the fallow.” At the end of last year, the Wises started sub-soil ripping to a depth of 35 to 40 cm on 75 cm spacing to increase water capture and break up the sub-soil compaction to improve crop growth. Six weeks ahead of planting they apply the final glyphosate spray and then add fertiliser, which they incorporate with the Kelly chain, with the added benefit of removing any weeds present. Liquid fertiliser applied at seeding promotes early seedling vigour and growth, which gives the crops a competitive advantage over weeds. They plant using a Tobin planter that achieves a good even strike in stubble, starting on the red soils as soon after rain as possible, then moving onto the black soils. Pre-emergent herbicide is applied after sowing legume crops and incorporated using the Kelly chain. Herbicide is applied in crop as well as for desiccation purposes in sorghum, mungbeans and chickpea. Being a spray contractor, Lance has also invested in an air boom on his sprayer that enables him to have much greater control of droplet size to match the environmental conditions, while also covering a larger area in a day. He says the elliptical cone delivers spray in both a forward and rear motion to achieve better coverage, even at lower water volumes. The controls in the cab allow the operator to adjust the spray quality from fine to extra course without changing nozzles on the boom and there is no need to have all the different nozzles to suit different conditions and products. The Wises operate a 12 m controlled traffic system and plant all their crops on 375 mm row spacings. Lance has increased the planting rate in sorghum from plants 40 cm apart in the row to 25–30 cm apart to quickly to shade the interspace and suppress weed growth.
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Case Study

Krui Pastoral Co, Condamine, Qld

East-west sowing between shade lines Half an hour west of Condamine on the western Darling Downs, Jake and Felicity Hamilton work with Jake’s father to farm 4500 ha of brigalow scrub, which was originally cleared for cattle grazing in the decades since 1975. Although the cattle are all gone now, the Hamiltons have maintained the shade lines of native vegetation left when the property was cleared and which occupy about 10 per cent of the farm’s area. Jake says the thick stand of buffel grass in the shade lines prevents other weeds from establishing and the buffel doesn’t move into crop areas. Most of the fencelines are also timbered, with the low soil moisture keeping a lid on weeds. Jake and Scott Hamilton, are well aware of the impact of herbicide resistance on their farm near Condamine, Qld. “When the farm was cleared, the shadelines were left running east west to maximise the shading effect for the livestock and now we are cropping east west in fairly large, square paddocks,”says Jake. “We are now taking advantage of the shading effect on the inter-row to suppress weed germination and growth.” Crop rows run east-west, parallel with tree lines left when the property was cleared, to provide shade for stock. Growing wheat / chickpea / wheat, with few opportunities for summer cropping in recent years, Jake has been working hard to keep on top of herbicide resistance in summer growing species including barnyard grass, liverseed grass, button grass and feathertop Rhodes grass. Not being able to grow summer crops on a regular basis, Jake has implemented a robust fallow management program to keep these weeds under control. “We try to double knock the glyphosate applications with paraquat, especially if the weed burden is high, there are large weeds present or weeds are not dying like they should,” he says. “And we always use full label rates to avoid herbicide resistance.” Jake regularly employs casual labourers to go around the farm on the ‘Gator with the spot spray rig to deal with any individual weed survivors, or if there are weedy patches they use the 6 m boom on the ‘gator’. Spot and patch spraying is time-consuming but very worthwhile. “Spot spraying summer grasses is quite time consuming but incredibly effective and cost efficient,”he says. “We also employ an agronomist to visit the farm once a fortnight to assist with monitoring and planning the weed control program.” “We know we are losing Group M [glyphosate] and can see resistance to Group A [grass selective] chemistry on button grass, which will leave us with very few herbicide options. We rotate crops as best we can so we can use different methods of weed control to try and break the resistance.” Button grass is proving to be quite a challenge to control with herbicide. Following two reasonable winter seasons, the 2016–17 summer was too hot for summer cropping, with no rain falling between September and February. Jake took this opportunity to do more laser levelling to remove the melon holes that are characteristic of brigalow scrub soils. Levelling brings about an immediate increase in yield and more even crops. “We purchased a second hand Caterpillar D11R and fitted it with TopCon GPS,”says Jake. “With the dozer we are able to cut 10 cm below grade on our first pass, which creates a good blend of topsoil with any exposed subsoil to avoid ‘scalping’the paddock.” Every four years the Hamiltons also incorporate 10 t/ha of manure to a depth of 15 cm and plan to utilise variable rate technology to apply manure to ameliorate some areas of soil fertility decline. “After using a chisel plough for several years to incorporate the manure, we are moving toward a program of deep ripping and deep application of phosphorus fertiliser to a depth of 40 to 50 cm, on 50 cm spacings,”says Jake. Since 2001 the farming system has been controlled traffic with 12 m bays, to suit 36 m sprayer, 24 m planter and 12 m header. Their new planter is configured for 375 mm (15″) spacings for wheat and barley, 750 mm (30″) for chickpeas, faba beans and mungbeans and 1500 mm (60″) sorghum and cotton. Jake also uses high seeding rates to maximise crop competition, along with their efforts to improve overall soil fertility and boost crop competitiveness. Although there are some risks associated with the short crop rotation Jake says residuals are doing a good job controlling weeds in-crop, with no late germinations evident. “We use residuals plus picloram and aminopyralid for fleabane control in wheat,” he says. “In chickpea we apply simazine and Balance and follow with an in-crop application of a Group A herbicide.” “If there are weeds present in-crop they usually don’t seed before harvest,” he says. “Black oats is a potential problem though if there is a spray miss.” They also apply pre-emergence herbicides Balance + Flame + diuron in some paddocks to keep them clean over summer while leaving their summer cropping options open in other paddocks.” The Hamiltons store planting seed on farm and grade all their seed through a mobile grader on the Easter long weekend, aiming to achieve a good clean sample –99 per cent purity. Jake spreads their frost risk by planting 50 per cent of the wheat area to Gregory in early May then sowing the chickpea area the following week. The remaining wheat area is sown later to Suntop or Crusader. After suffering severe frost damage in late August 2017 the Hamiltons changed their planting schedule to reduce their frost risk. Jake says late frosts can be a problem in the Condamine area and can badly affect chickpea crops if the temperature drops to zero or below during flowering or podding. “We aim to have all our wheat planted between 7 and 21 May and then plant chickpeas after that,”he says. “Our new planting equipment has superior breakout force, compared to our old machine, which allows us to plant chickpeas to a depth of 200 mm (8″). Planting at this depth delays seedling emergence until after the first week of June, pushing the flowering window back a fortnight, closer to the warmer weather of spring.” “Chickpea makes a huge difference to our farming system with better wheat yields, less fertiliser and softer soil.”
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Case Study

Bruce family, Alford SA

Keeping pressure on brome grass with HWSC Brothers Gary, Paul and Bronte Bruce farm at Alford on the Yorke Peninsula, SA have used harvest weed seed capture as an important tool in their weed management program to bring down grass weed numbers in their continuous cropping business. For the last 15 to 20 years the Bruce family has followed a 3-year rotation of wheat – barley – legume, having exchanged field peas for lentils in the legume phase in recent years. They found that producing export hay on grassy paddocks was a very effective way to manage grass weed seedbank, to the point where they had only one paddock of hay in 2016 and no hay in 2017. Gary Bruce, together with the family’s agronomist Chris Davey, YP-AG sets out a plan for the season, including our weed management program, with different strategies used depending on whether there is a wet or a dry start. “Hay production is hard work and now that we don’t have much of a grass weed problem we are taking hay out of the rotation for a while,” says Gary. “The hard work was certainly worth it in terms of regaining control over herbicide resistant weeds on the farm. Now we’d like to keep more crop residue on the paddocks to improve the hardsetting nature of the soil here.” Having used a chaff cart for many years, the Bruce’s were well aware of the benefits of capturing weed seed in the chaff stream but Gary was very interested to hear HWSC advocate and WA grower, Ray Harrington, speak at a field day about chaff lining. In 2017 harvest they used chaff line chutes on two headers for the first time. As usual they learnt a lot in their first harvest and have plans to make even better use of the system this season. Gary is very aware of the fact that there is very limited research on the long-term impact of chaff lining on weed management. “Our farm is partially set up for controlled traffic with 12 m and 36 m gear so the chaff line ends up on a spray track every third run,” he says. “We found starting the harvester on a spray track at the edge makes the best use of the wheeltracks. If we go to a full CTF system we will probably change to using a chaff deck system but the chaff lining chute is certainly a cheap and effective way to confine weeds to a small area of the paddock while also retaining the stubble.” Gary’s farm is partially set up for controlled traffic with 12 m and 36 m gear so the chaff line ends up on a spray track every third run. So far they have found using the chaff lining chute is a cheap and effective way to confine weeds to a small area of the paddock while also retaining the stubble. HWSC and late germination Brome grass is the most problematic weed on the Bruce’s farm with limited options for control in the cereal phase. There are limited chemical control options to kill early germinating brome grass before seeding and so Gary relies on HWSC to take care of late germinating cohorts. They recognise that hay making has played an important part in keeping this weed in check and acknowledge this could be more difficult if they get out of hay production altogether. All crops are sown to achieve greatest crop competition possible using 25 cm row spacing and cultivars that are well suited to the different soil types. Two-thirds of the farm is inter-row sown while paddocks with hardsetting topsoil generally follow the same furrow as the previous year. As the soil improves through increased residue retention Gary hopes most of the farm will eventually be sown in the inter-row. Generally they find, Scepter wheat yields better than Mace, Compass barley produces the most straw, PBA Bolt lentils give salt and boron tolerance where it’s needed and PBA Hurricane lentils offer Group B herbicide tolerance. “Early in April we usually speak with our agronomist, Chris Davey, about a plan for the season, including our weed management program,” says Gary. “For example, wet and dry starts need different strategies such as ensuring there is sufficient moisture to activate metribuzin and propyzamide before sowing lentils. We have also experienced more summer rainfall recently and often need to do two sprays for summer weed control.” Other resources: Implementing the WeedSmart Big 6 on the Yorke Peninsula

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