Zapping weeds with lasers to protect environment

By Charles Carter, 12/9/22

Earlier this year US startup Carbon Robotics launched a bigger version of their autonomous LaserWeeder machine which is instead pulled along by a tractor. As with their previous machine, their latest innovation uses computer vision to detect the exact location of weeds and fires lasers to reduce them to ashes.

Using lasers to eradicate weeds replaces the use of harmful herbicides, tilling and/or back-breaking labour, boosting sustainability and crop yields, and lowering costs.

How does it work?

A series of hi-resolution cameras on the underside of the machine stream real-time imagery to an onboard computer which runs Artificial Intelligence-led computer vision analytics. The exact locations of the crops and weeds are identified, including the vulnerable meristem – the region of the weed that is actively growing and dividing.

Carbon dioxide lasers with 150W power rating are then fired at the meristem with millimeter accuracy and a 50 millisecond gap between bursts.

The approach is effective in specialty row crops such as lettuce, kale and broccoli.

The tractor-towed LaserWeeder is 20-foot wide and features 30 industrial CO2 lasers, which is 3X as many as the self-driving LaserWeeder from 2021.

Tangent box (Carbon – > Tollund Man): The Tollund Man is a naturally mummified corpse of a man who lived during the 5th century BC and was found in a bog in Denmark. The age of the corpse was determined using carbon dating. (Hmm…OK, but why? Tangential thinking is essential for creativity and innovation, and Superinnovators promote it!)

What are the potential benefits?

Usually, weeds are removed either by spraying herbicides, tilling or pulling them out by hand. Herbicides are chemicals that are toxic to weeds but if they run off fields and contaminate wider areas they can have a detrimental impact on plants and animals in the ecosystem.

Tilling consists of disturbing the soil by dragging metal blades through it. One outcome of this is it buries weed seeds that would otherwise have germinated on the surface, reducing weed density.

But the downsides are that it disrupts soil structure, accelerating surface water runoff and soil erosion.

By replacing all three removal methods, laser weeding provides a more sustainable, organic and efficient approach.

According to Carbon Robotics, farmers using their LaserWeeders are seeing 80% savings in weed management costs, with a break-even period of 2-3 years.

What are the costs?

In an interview with Modern Farmer publication in late 2021, Carbon Robotics CEO Paul Mikesell said the cost of the smaller autonomous LaserWeeder is comparable to a mid-size tractor which can range between $25k and $50k.