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This is a GRDC podcast.

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Fiona Fagan: Hello, I'm Fiona Fagan. Precision weed management is where optical sensors and remote and sensor weed mapping systems are used to target weeds and therefore cut herbicide costs. The technology is becoming more widely available, which is why GRDC is investing in a series of case studies, to explore the benefits and costs related to these technologies. One of those case studies is Warakirri Cropping, one of Australia's largest grain growers owned by the Rest Super Fund. Warakirri has 11 cropping farms across New South Wales, Queensland, Victoria and Western Australia and has made a substantial investment in precision weed management technologies. I paid a visit to Warakirri's Baingarra property in the north Wimmera region of Victoria to watch a device called the WEED-IT in action. Baingarra's Junior Assistant Farm Manager, Patrick Anderson, showed me how it works.

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Patrick Anderson: It's an 11,000 litre sprayer on 36m. It's towed by a John 39DR articulated tractor. So there's cameras mounted to the boom. They emit a red light, which is then measured in near infrared to measure if there's a plant or not there, and spray the weed with one nozzle or two, depending how big. You can only detect green plants on the soil. Can't do green-on-green.

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Fiona Fagan: So economically a big investment. But what sort of time and money has it saved you here?

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Patrick Anderson: We can get into paddocks quicker, whereas in a traditional sense we would have to wait for more weeds to germinate to make it more economical. So these sprayers run all summer, we don't stop them. Generally, they spray between 10 and 30 per cent of a paddock as they go around the farm continuously. We've got the benefit of using this all year round because it's a dual-purpose sprayer. We can use it as a broad acre sprayer during the cropping season, and then run it all summer with the cameras on.

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Fiona Fagan: Can it work in any condition?

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Patrick Anderson: We have trouble with spraying after rain. The cameras seem to detect water as well as plant material. Some learning curves we've had is sensitivities. You can change the sensitivity so you can detect really big weeds or really small weeds.

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Fiona Fagan: Baingarra's Farm Manager, Jono Robinson, says using precision weed technology cuts back on chemicals and increases savings. So can you go into the specifics of the economics? How has it changed the amount of chemicals that you use?

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Jono Robinson: So a blanket spray for us will be say 1.5L of Roundup, 100mm of Garlon, 150-200mm of Vista. To spray that blanket over the whole farm, it can cost you $20, $30, $40 a hectare sometimes where you can get that down to, if you're only spraying 20 per cent, you can actually increase the rate to get a better kill and still save a lot of money doing that as well.

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Fiona Fagan: So how accurate is it?

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Jono Robinson: They're incredibly accurate. They'll pick up weeds that are only sometimes one centimetre small through to large ones. There's different settings in the machine you get four different settings. Sensitivity settings.

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Fiona Fagan: What other features of the technology do you like? For example, safety?

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Jono Robinson: From a safety point of view, you're not handling as much chemical because you're not spraying it out as much. One load can sometimes do 300 or 400 hectares, so staff aren't having to always constantly come back and fill up and constantly handling chemicals and mixing more brews.

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Fiona Fagan: Is it worth a capital, say, for a smaller landholder? Is it worth the capital?

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Jono Robinson: I think it is, with the savings alone. There's a lot of variety out there, they don't all need to have the same as what we've got. But you can get smaller versions that it would be cheaper to afford and still have that same saving, and you can use them in crop as well. You can have them retrofitted other sort of machines as well, so you're not having to buy a whole boom. You can fit them to any type of boom just about these days.

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Fiona Fagan: John Stevenson is Warakirri Cropping's Southern Regional Manager. He told me about Warakirri Cropping's investment in precision weed management in broader terms.

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John Stevenson: I look after four farms, two in the Riverina and two in the Wimmera Mallee in Victoria. We're part of a bigger business that has 11 farms around Australia and we specialise in dryland grain production, basically all on stored moisture or in-season rain. So weed management's really important for us.

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Fiona Fagan: As far as precision weed management goes. What other technologies do you use around the country?

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John Stevenson: The optical spray technology would be our main precision tool at the moment. I guess we are looking into drone mapping and using targeted weed seeking from our self-propelled boom sprays. We also use NDVI considerably, both in crop and in fallow, and that can help us find patches of high intensity weed growth when we might not necessarily get around all the paddocks. We have some very big farms up to 24,000 hectares, so it's hard to keep an eye on everything. So certainly images from space help us a lot.

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Fiona Fagan: And how about the Swarmbot?

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John Stevenson: Yeah, we've got one Swarmbot running with a WEED-IT machine on it up at Goondiwindi, and I'm pretty sure there's a second one on order that's basically doing the same job as we're doing, but autonomously. So we're leaving it to run under the correct weather parameters whenever it senses them being right. So it's fantastic.

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Fiona Fagan: So I was going to ask that. So yeah. What is the difference between a WEED-IT and a Swarmbot?

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John Stevenson: A person at the wheel I think is the biggest difference. And the ability to be going when the conditions are right and stop when they're not. So it's very hard to turn humans on and off at various times of the day and night. The swarmbot is brilliant because it's monitoring continuously the weather conditions. As long as we've got fuel and brew in the tank, It'll start itself up and go spraying and keep chipping away at a job.

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Fiona Fagan: That's incredible.

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John Stevenson: Yeah, it's amazing technology and we'd love to go further down the autonomous path, but I think that's all work in progress as far as the tech goes. The Swarmbots, well-supported up in the northern region and certainly doing a good job for us. And we're looking at other ways to use that type of technology for some of the more mundane jobs we do around the place. The optical sprayers, while they're very good, they can be very tedious to drive. It's really high tech piece of gear, but a tank can last for a very long time. It's at a very steady speed compared to conventional spraying and almost causes boredom fatigue with operators, so it's fantastic to have something that'll do it itself.

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Fiona Fagan: So as far as Warwick cropping goes, what is your overall strategy with regards to precision weed management?

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John Stevenson: Our overall strategy really is to use it as much as we can, and that's a challenge. We would love to see these machines being used up to 50 per cent jobs, but unfortunately they lose a bit of efficiency when we get to that. So when we've got higher weed pressures, we tend to revert back to the broadacre booms just to get over the whole farm as quickly as we can. So often we'll have two or three self-propelled booms or trailing booms in addition to our optical spray technology, and sometimes the team just needs to get in and get the job done. I think our strategy is to use it as much as we can within limitations, so we probably need more of them to give us the capacity to push them harder. But they use 100 litre water rates. So once you start getting up to sort of 50 per cent coverage, you'll start going through tanks pretty quickly. And obviously we just have that lower working speed so it can really reduce your efficiency.

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Fiona Fagan: So what difference has precision weed management made to operations at Warakirri Cropping?

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John Stevenson: It sort of has integrated very well with what we were already doing. It's just a different way of doing the job but a better way of doing it. And often the camera sprayer will be used to come in and do a double knock through summer. So if we've got any tougher weeds and we've got a lot of broadleaf or grass-based volunteers will come in and hit that hard with the boom spray, but not with high rates. And then we'll back it up within the fortnight.

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Fiona Fagan: What about cost saving. Financially, what sort of cost savings are taking place?

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John Stevenson: Cost savings can be huge. So you come back even with a high rate of paraquat as a double knock. If we're doing maybe five per cent on maybe a two and a half or three litre per hectare brew, we're back to within a dollar to $2 a hectare for chemical based compared to $20 a hectare. So it's pretty huge the savings that we can make. It's also a lot less chemical handling for our teams, which is great and a lot less exposure because you don't have to fill up as often. So you know you can get through the best part of a day with the big tanks we've got now.

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Fiona Fagan: So how long have you used precision weed management technology and what are the benefits?

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John Stevenson: Warakirri Cropping's used precision weed technology in the form of optical sprayers since 2013. We were a bit unsure about how long the technology was going to last, but pleased to say the 2013 optical sprayer is still functioning today. 11 years later, it's very robust industrial technology that just keeps working. It seems to be very simple. So happy to say that it's been a good investment and is working well, and we'll continue to use optical spray technology. We have also got into some Bilberry type systems, which is more of a vision base. And so we're sort of working with that business at the moment to collect data and just to see where that's going to take us. And the hope is that one day we'll get to the point where we can do green-on-green spraying so we can actually target weeds in-crop.

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Fiona Fagan: So what are some of the challenges with precision weed management?

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John Stevenson: There's a few challenges that we've been finding. Interestingly, barley straw can give us a bit of grief. Something that reflects from barley straw that's not properly ripe will trigger a misfire. So it thinks there's a weed there and there's not. If there's any dew or any moisture on the stubble when we're spraying, that'll also trigger a misfire. So we've just got to be a bit picky about when we use it. And also shading, so if the sensors can't see the weed, they won't fire. So it's really wise when you're doing multiple passes to alternate the direction of travel between each pass. So if you're going north on your first pass, come the same run south on the next pass to try and avoid that shadowing issue or shading issue when weeds are hidden behind residue.

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Fiona Fagan: And what's your message to other growers about precision weed management? Would you recommend it?

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John Stevenson: I'd highly recommend it. And even if it's contract-based, if you've got contract availability, you will find savings. It may seem like an expensive cost to get a contractor in to do the work, but the savings that you will make on chemical will far outweigh the cost of the contractor. Weeds to me, mean problems and financial as well as visual. And that's not hard to see when you see difficult weeds, weeds people tend to let go like sow thistle, heliotrope, fleabane. They have a massive impact on your stored soil moisture and obviously your crop yields beyond that.

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Fiona Fagan: Jessica Sleigh is Warakirri Cropping's Sustainability Officer.

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Jess Sleigh: Precision weed management for us is more sustainable because we're reducing the inputs and therefore having flow on effects to the environment and inevitably reducing the weeds long term.

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Fiona Fagan: So precision agriculture in general, how far has it come and what are some technologies we might see in the future?

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Jess Sleigh: So precision ag for us as a business is hugely important. We've got our own team allocated to precision ag. So they bring together all the data, analyse our data across the portfolio and then we can make informed management decisions based on the data. So we're making informed decisions based on that data. But with that being said there's still a long way to go with that element. Technology and innovation is evolving every day, all the time in the agricultural industry, so we hope to be at the forefront of those changes in technology. So it's maintaining and being adaptive to those changes in technology. But there are some really exciting things in the pipeline.

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Fiona Fagan: That was Warakirri Cropping's Sustainability Officer, Jessica Sleigh. Earlier, I spoke to Warakirri Cropping's Southern Regional Manager John Stevenson, Baingarra Farm Manager Jono Robinson and Baingarra Junior Assistant Farm Manager Patrick Anderson. What a fascinating insight into precision weed management technologies and some predictions about what we might see coming onto the market in the near future. I'm Fiona Fagan. This has been a GRDC podcast. Thanks for listening.

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A note for listeners. This case study does not cover all products in the market. Different products may have different costs and benefits.