Australasian Science: Australia's authority on science since 1938

Lasers Slash Herbicide Use

By Stephen Luntz

Weed identification technology could slash herbicide use in farming, saving money and the environment while reducing concerns about potential health effects.

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Edith Cowan University’s (ECU) Photonic Weed Detection System scans a field with three lasers, two in the visible light range and one in the infrared. Weeds will reflect back different proportions of the light from each laser than the planted crop, allowing the system to automatically distinguish friend from foe, hitting only the weeds with a stream of targeted herbicide. By preventing the need to spray weed removers across the whole field, the process can cut herbicide use by 75%.

ECU Electron Research Institute Director Prof Kamal Alameh says the system “cannot distinguish everything from everything” so it must be tuned to distinguish the most common weeds from the crop to be protected. Consequently, rarer weeds may escape being sprayed, but by their nature these are a small problem.

“For sugar crops 95% of the weeds are one species,” he says. When protecting cotton, which is threatened by multiple weeds, the system is simply programmed to spray anything with a different light signature from cotton itself.

“We could distinguish more species if we added more lasers, but that would increase the cost and slow the system down as more processing would be required,” Alameh says.

Australian farmers spend almost a billion dollars per year on herbicide, and the amount is rising. Photonic Detection Systems, ECU’s corporate partner, will lease the...

The full text of this article can be purchased from Informit.