By: Brandon Long

They may be on the cutting edge of technology, but robots rolling out across Australian farms are now incorporating tactics from the past to kill weeds.

Hand-weeding and mechanical cultivation fell out of favor following the invention of herbicides in the 1940s.

But robots, imported to Australia from manufacturers in countries such as Denmark and the United States, are reviving these weed control methods to slash chemical use.

Guided by GPS and cameras, the machines use knives and wires to take out pest plants by "hand" instead of spraying.

The inventions are helping farmers such as fourth-generation Queensland vegetable grower Troy Qualischefski reduce input costs, and improve crop and farm health.

The director, owner and manager of Qualipac, which grows and packages produce at several Queensland locations including Gatton and Inglewood, bought a FarmDroid FD20 from Denmark in July and a Stout Smart Cultivator from the U.S. in October.

Qualischefski, who has begun trialling the robots, said he wanted to reduce herbicide use in the stage before the crop emerged.

"One of our goals at the moment is to try to figure out how to reduce our pre-emergent chemical; to try to stop the weeds coming up.

"If we can slowly phase that out and then just mechanically weed, I believe we'll have a stronger plant, and we will have a more even harvest."

The Danish machine is a solar-powered driverless robot that weeds and seeds using GPS, while the American set-up attaches to a tractor, weeding using cameras and artificial intelligence (AI).

Powered by two batteries that are charged by four solar panels, FarmDroid claims the bot can run 24 hours a day in sunny conditions and can cover about 900 meters an hour, or 6 hectares a day.

While these are built to work in horticulture crops, there are similar robots operating in grain and cotton-growing regions.

Herbicides Change Agriculture

Hand weeding and later turning over the soil or "tilling" has largely been replaced in many countries following the invention of herbicides, as no-till farming not only reduces fuel use and labor, it also retains soil moisture, preventing erosion and increasing crop yields.

Over the years, farmers have made a concerted effort to apply chemicals more efficiently, going from blanket spraying a paddock, to attaching camera spot sprayers to their machines and more recently, rolling out autonomous robots with spot sprayers.

The proportion of Australian cropping land under no-till is about 80%, and while no-till still has a valid place in modern agriculture, farmers are looking for other options as chemical costs begin to eat into farm budgets, weeds develop resistance, and societal expectations change.

Weeds cost Australian farmers almost $5 billion a year in management and losses, and the use of agricultural chemicals such as herbicides, insecticides, miticides, fungicides, and antibiotics has doubled since 1992, reaching 50,000 tons per year in 2017–18.

Robot Weeders Are Big Business

Mechanical weeding tech is being backed by big business, with owner of major machinery companies CASE and New Holland, CNH, buying a minority stake in Stout last year.

Stout director of sales operations Sal Espinoza said the company's machine was trained to work in a variety of crops, from lettuce, broccoli and cauliflower, to kale, celery and parsley.

Espinoza said the machine's software did not choose which plant to kill based simply on its color.

"It's legitimate AI where it's actually understanding what that commodity is, so even if you were to put a plate of salad under the camera system, it's actually going to know that that is, in fact, lettuce," Espinoza said.

Qualipac's two robots, along with several others, were on display at the Gatton AgTech Showcase held at the Gatton Smart Farm last week.

The farm is a partnership between the Queensland government and federal government-funded research and development not-for-profit, Hort Innovation.

Speaking at the event, Queensland Department of Agriculture and Fisheries (DAF) director-general Chris Sarra said it was "wonderful" to see the industry leading the nation and adopting such cutting-edge technologies.

"New technology is critical to expanding our markets and supply chains and meeting challenges in labour management, product quality, climate variability and supply chain wastage," Sarra said.

Hort Innovation chief executive Brett Fifield said the not-for-profit's investments looked at reducing the industry's reliance on water, pesticide and fertiliser, "not [only] maintaining the natural ecosystem, but actually improving it".

Lockyer Valley Growers president Michael Sippel said to remain viable in the farming industry over the next five to 10 years, it was more critical than ever to seek innovative approaches.

"At the very least, this innovation helps us break free from the cycle of insanity and offer us new tools to work with," Sippel said.

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