Resources

Articles

View all
Article
Ask an Expert

How can I be certain that herbicide residues in the soil have fully degraded at planting?

In the course of a chemical fallow there are often several applications of herbicide and some residues may still be present on or near the soil surface when it is time to plant the next crop. In particularly dry years, residues may even carryover from the crop prior to the fallow. NSW Department of Primary Industries soil scientist, Dr Mick Rose, says there has been concern in recent years about the effect these residues may have on soil microbial activity and on the establishment and growth of crops following the fallow, even after the plant back period. Dr Mick Rose, DPI NSW soils researcher, is developing tests and predictive models to support growers in their decisions about crop choice after using residual herbicides. (Photo: GRDC). “Glyphosate has been the most commonly used knockdown herbicide in northern fallows for several decades and more recently growers have been looking to use more diverse programs that include chemicals with residual activity on weeds,” he says. “The increased use of imazapic and diuron have been of most concern to growers when choosing the next crop, particularly after a low rainfall fallow period.” With investment from GRDC, Mick has been working on a project led by Dr Michael Widderick from the Department of Agriculture and Fisheries, Queensland to develop a soil test for imazapic and diuron residues that will indicate damaging residue levels and help growers to decide which crops would be safe to plant in a paddock. “We are determining the threshold levels of residues of these two herbicides at which crop damage is likely for six crops, both winter and summer growing, in a range of soil types,” he says. In earlier work he also looked at the level of glyphosate residue in soils around the country at planting time and the impact these residues have on soil biological processes. “We found that residues of glyphosate were commonly detected in the soil at planting but there was no indication that the herbicide was adversely affecting soil biological activity,” says Mick. “This suggests that the label recommendations are suitable and the proper application of glyphosate in Australia is not posing a threat to soil health.” “For growers to be able to keep using glyphosate they need to implement the WeedSmart Big 6 strategy, including using diverse chemistry in fallows,” he says. “Residual herbicides are a useful tool for growers but there are some gaps in our knowledge about how these herbicides break down in different soils and under different seasonal conditions.” Why not just follow the plant back recommendations on the label? In brief: The label provides the minimum plant back period provided certain environmental conditions are met. There is a possibility of crop injury even though plant back periods are observed. The details: Many factors affect the bioavailability of a herbicide in the soil. For example, even though a clay soil and a sandy soil might have similar residue levels, more herbicide will be available for uptake in the sandy soil. More rain will increase the rate of breakdown, but it is not known exactly how much rain will ensure the specific soil is ‘safe’ to plant into. Another important factor is that many things can contribute to a germination failure. In some situations, residual herbicide may be suspected as the culprit, but can be difficult to either rule it in or out with certainty when diagnosing the reason for a problem at planting. If herbicide residues in the plant tissue can be shown to be phytotoxic, then another, less susceptible crop could be sown into the paddock. Dr Annie Ruttledge, DAF Qld weeds researcher, inspecting chickpea plants growing in soils containing different levels of imazapic and diuron herbicide residue. What effects can herbicide residues have on emerging crops? In brief: The herbicide itself can inhibit germination and growth, or it can exacerbate other factors, such as root disease. The details: At different levels of bioavailability, herbicide residues will have different effects on crop plants. If the herbicide is readily available to the plant, then susceptible crops will take it up from the soil and it can have phytotoxic effects ranging from suppressed vigour to yellowing and potentially plant death. Testing the plant tissue of a struggling crop can show if the leaves contain sufficient herbicide to have caused the observed symptoms. Some herbicide residues in soil can also ‘prune’ plant roots, particularly the fine roots that help access moisture and nutrients. Obviously, if the young plants are struggling to access resources then they will be less vigorous and possibly die. Damaged roots are also more susceptible to water stress, disease and poor nodulation in legumes, making it difficult to determine the initial cause of the problem in the field. If herbicide residues are shown to be the problem then a more tolerant crop can be sown, speeding up the breakdown of the residue and there will be more rainfall events before the next cropping season comes around. Seedling emergence and establishment is being measured for six crops (winter and summer) in the presence of different levels of herbicide. What pre-planting soil tests are being developed to give growers confidence to plant? In brief: The current project is establishing phytotoxicity thresholds for six summer and winter crops in a range of soil types, for two herbicides – imazapic and diuron. The details: By mid-2021 the aim is to have established the thresholds so that soil could be tested pre-plant to determine what crops would be safe to plant. This will give growers confidence to use these herbicides in a diverse strategy to manage weeds like feathertop Rhodes grass in the fallow, while avoiding germination or establishment failures in the following crop. Spray records play an important role in the management of these herbicides and mistakes can easily be made if the spray history for the past several years is not taken into account. In time, growers and their agronomists will gain a better understanding of how these herbicide residues behave in the soils on a particular property and will be able to make herbicide application and crop rotation decisions with more confidence. In another project with the Soil CRC, Mick is developing a predictive model for herbicide breakdown for a wider range of herbicides used in southern and western cropping systems. Until these tests and models become available, the use of an in-field or pot bioassay with a susceptible crop can be helpful in determining potential plant back issues.   Related resources Herbicide residues in soil – the scale and significance (GRDC Update paper) Herbicide residues in soil (GRDC Podcast)
Article
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
Article
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.
Article
News

More lambs, less weeds in sheep containment systems

Livestock containment areas allow the Eagles to rest their pastures and fodder crops, efficiently use a variety of feeds and restrict the spread of weed seeds. On top of this they have also seen benefits in growth rates and lambing percentages. Sam says the six or seven hectares they have available for containment was not expensive to build and has made it much easier to manage their livestock and cropping enterprises. “I’d definitely recommend building containment areas for sheep,” he says. “It is such a simple concept that has so many benefits. They really help to manage ground cover on your pastures and cropping paddocks, and in dry times they make feeding out much less stressful. In the last drought we had up to 6500 sheep in containment, including lambs, and I could feed them all in less than three hours, and didn’t have to feed every day.” Sam and Emily use the containment areas for several purposes throughout the year. Although they generally keep their pasture and cropping paddocks separate, the sheep play an important role in weed management across the whole farm. “The containment areas allow us to bring in feed from outside if necessary and feed out screenings from our own grain, being confident that any weed seeds that come with that feed won’t be spread around the farm,” says Sam. “It is easy to manage any weeds that germinate in such a defined and small area of the farm. “When we buy in sheep we shear them as soon as they arrive to remove any risk of them introducing weeds like Bathurst burr,” he says. “We use the containment areas to avoid overgrazing pastures so the sheep eat the weeds like barley grass as well as the more palatable species. They also provide an effective double knock effect for weeds that have herbicide resistance.” The Eagles cut weedy paddocks for hay or silage and feed it out in the containment areas where they can control any weeds that germinate. Sam says above-ground pit silage has been very cost effective at around $10 a cubic meter to cut the silage and store it under a tarp before feeding out in the containment paddocks. “Silage is a very good weed control tactic,” he says. “You cut it early, so you are stopping weed seed set, and after three days of good weather you can spray out the paddock for a spray fallow.” The Eagles prefer to either graze a crop fully or grow it for grain, having found that the ‘grain and graze’ tactic for dual purpose crops had an unacceptable yield penalty and opened up the canopy to allow weeds to grow through and compete in the grain phase. They have found Moby barley plus clover to be the best cover crop to graze and then spray out. Oats and pasture are both cut either for hay or silage to conserve fodder and remove weed seeds. “In the cropping paddocks sheep will eat most of the weeds that evolve herbicide resistance, like wild radish, annual ryegrass, fleabane and whip thistle. They also generate cash flow from cover crops and from grain crops that don’t go through to harvest due to drought, flood, weeds or frost,” says Sam. “Over summer the sheep reduce our herbicide costs and reduce the stubble load, which makes sowing easier. Once the feed supply runs out, we put the sheep into containment until they start to lamb. This allows the pastures and crops to get ahead and gives us good feed to put the ewes into for lambing.” “The sheep can make inter-row sowing more difficult in our CTF system so we have to be careful to cut the stubble 300 mm or less above ground level so the stalks don’t lodge across the inter-row as the sheep graze the stubbles,” he says.  Having used narrow windrow burning as their harvest weed seed control tactic for six years, Sam and Emily used a contract harvester with an impact mill for their harvester for the 2018 season. They were pleased with the job the mill did and are looking to purchase one of their own once the technology matures a little more. They use crop-topping in pulses and windrowing in canola to stop weed seed set and also spray herbicide under the cutter bar in canola. “We test weeds for herbicide resistance so we know what still works and plan out a diverse herbicide program with multiple chemical groups used in a broad crop rotation,” says Sam. Other than the grazing and weed management benefits, Sam and Emily have also found numerous productivity benefits for their 2500-strong merino flock. Using the containment yards for joining has seen increased conception rates and after preg-testing their ewes, Sam and Emily make separate mobs for the twins and singles so they can better manage the ewe’s nutrition while in containment. Once the lambs are weaned and are brought into containment their growth and feed utilisation rates are higher than when paddock grazed, meaning the returns on feed inputs are higher and the Eagles are able to either turn off hoggets earlier or at a higher weight. Building and using containment areas Size and design – they can be any size, provided an allowance is made for 2 to 5 m2 per sheep (2000 to 5000 sheep per ha). At the right stocking density the containment yards compact well and do not generate dust or strong odour. Place the food and water sources as far away from each other as possible in each containment yard – this helps keep the water troughs clean. Water – sheep require 6 litres of water each per day and more in very hot weather. Flow is more important than pressure, so use thicker pipe (e.g. 30 to 50 mm) to supply the troughs. Feeders – feed can be placed in self-feeders, feed troughs or on the ground. Shade – think about shade when designing the containment areas and look for ways to provide as much shade as possible. Protect any established trees. Feedstuffs – utilise a variety of feeds such as screenings, canola, hay, purchased grain and silage. Match the nutrient value of the feed with the class of animal you are feeding and supply any necessary mineral supplements. Get advice if you don’t have a good knowledge of animal nutrition. Stock health – give sheep 6-in-1 vaccines and drench before putting a mob into containment. Key benefits Less feed wastage means feed costs are reduced and productivity is higher with more lambs produced (higher conception rate) and faster weight gain compared to paddock grazing. The containment paddocks can have a variety of uses including being a fire break, lamb feedlot, shearing holding yard and joining paddock. Move sheep out once lambing commences. Holding sheep in the containment paddocks allows the pastures and fodder crops to create a green wedge of feed before being grazed. They also provide a suitable place to hold sheep once the pastures and fodder crops have run out in summer, maintaining groundcover levels across the farm. Good for your mental health in drought conditions as you don’t have to drive around dry paddocks every day, feeding doesn’t take as long each day, ground cover is preserved across the farm and the sheep can be kept in good condition. More information Eagle family case study Sheep confinement area fact sheet  

Podcasts

View all
Audio
Podcast

Regional Update – Ben Webb, Kojonup, WA

WA farmer Ben Webb joins us on the Regional Update to give us an update on how his year is panning out. He gives some insights into how he’s gone using chaff carts and talks about a few other novel approaches he uses on his farm. If you’d like to find out more about Ben’s farming system, you can check out the case study on him we did here.
Audio
Podcast

Voraxor crash course and why you might consider a double paraquat knockdown

On this week’s podcast we take a look at a different approach to double knocks. WA-based Farmanco agronomist, Mark Lawrence (pictured) shares with us the benefits of double paraquat and other strategies his clients in the medium to high rainfall zone in WA’s south west region are using. We also find out more about BASF’s new Group G herbicide, Voraxor. BASF Technical Development Manager Ian Francis joins us to tell us more about their new Group G pre-emergent broadleaf weed herbicide and how it can fit into farming systems. BASF Technical Development Manager Ian Francis ____________________________________________________________ Podcast presenters: Jessica Strauss & Peter Newman Podcast producer: Jessica Strauss
Audio
Podcast

Regional Update – Matt Bissett, Swan Hill, Vic

On this episode of the Regional Update, we catch up with Agrivision Agronomy Consultant Matt Bissett. He’s based in Swan Hill in the Victorian Mallee. He gives us a regional update on the Central and Southern Mallee and Northern Wimmera.

Case Studies

View all
Article
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
Article
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.
Article
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
Article
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.”

Videos

View all
Video
Webinar

How to make the right decision on using Group Gs in the Northern cropping system

Group Gs have a place in northern cropping systems both in summer and winter crop scenarios. We ask Andrew Somervaille to explain Group G use in both systems and the most optimum use of different Group G products given the range of seasonal conditions in the northern cropping region.
Video
Webinar

How do I make the right decision on using Group Gs?

Choosing and applying the right pre-emergent herbicide can be difficult, particularly if herbicide resistance is becoming a challenge in a no-till system. Join Dr Chris Preston, University of Adelaide (UA) professor weed management and WeedSmart’s Chris Davey as they explain the new Group G chemistry and de-mystifies which Group G works best for winter cropping systems.
Video
Video

Double breaks – a double shot at annual ryegrass

Perhaps you’re a ‘short black’ wheat-canola type, strong on inputs? Or a ‘long black’ type who likes to dilute their rotations a bit more? Or are you a ‘double shot’, throwing in a few break crops in a row for maximum effect? When it comes to managing annual ryegrass populations, Tony Swan and the research team from CSIRO Plant Industry and FarmLink, have shown that ‘double shots’ are the key. Growing two break crops in sequence (broadleaf crop, hay crop or long fallow) was more effective in reducing resistant ryegrass numbers to manageable levels than a single break crop or continuous wheat over a three-year rotation. And it can still be profitable.

Fact Sheets

View all
Fact Sheet

Farm Business Management Factsheet

Key points Effective decision-making is at the core of successful farm business management. Making informed, logical and timely business decisions is crucial to achieving business objectivess. Understand the different elements that influence how decisions are made and the possible outcomes. Consider who is responsible for the final decisions in the different areas of your farm business. Ensure the decision is finalised and implemented in a timely manner. Want to link to this fact sheet/publication? Full article can be found here
Fact Sheet

Wild radish management and strategies to address herbicide resistance

Wild radish (Raphanus raphanistrum) is one of the most widespread and competitive broadleaf weeds of Australian cereal-growing regions. Increasing resistance to multiple herbicide modes of action is forcing growers to adopt diverse and integrated weed-control strategies to deal with this weed.
Fact Sheet

Common weeds of grain cropping

GRDC's 'The Common Weeds of Grain Cropping – The Ute Guide' aims to help growers, advisers, researchers and students to identify the most common weeds of grain cropping systems in Australia.
Fact Sheet

Northern IWM factsheet – common sowthistle

Common sowthistle (Sonchus oleraceus L.), also known as milk thistle, is a dicotyledonous annual weed. The plants are erect and fleshy and possess hollow, smooth stems that exude a milky latex when damaged. The weed can grow up to 1.5 m in height. Plants of common sowthistle can be either present as a rosette or upright in their growth form. Its leaves may vary in colour and the amount of serration on their margins (Figure 1). Common sowthistle seeds possess a pappus, which helps in seed dispersal through the wind.

Subscribe to the WeedSmart Newsletter