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Comment by fchollet | Hacker News Reader

I suspect this would result in rather superficial weed destruction, since the roots underground would be unharmed and would cause the weed to regrow a few days later. Unrooting the weeds definitely sounds more reliable to me.

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> Unrooting the weeds definitely sounds more reliable to me.

The robot in the article just pushed the weed underground a few inches. I imagine that some weeds would just pop back after a week, and that the robot would just punch them down again.

So you now you have to run your fleet of robot weeders over the field twice? That seems like a waste of time and $ when you could achieve the desired result in a single pass. every extra pass is also more soil compaction.

You would already need to run the weeder every few days to catch future weeds. Much of it would be about disrupting the weeds while crops get established.

Pushing the weeds below the surface is probably less disruptive to the surrounding crops than tearing out the roots. And since you have to run the machine constantly anyway to prevent new weeds from establishing themselves, just poking them down repeatedly will eventually starve them of sunlight and kill them, or at least prevent them from ever growing large enough to cause a problem.

If you run the robot every week, burning off the stem & leaves, the plant will eventually starve.

Around here, we have an invasive species called scotch broom. If you cut off the plant at ground level, it will grow back. But if you cut it off after it flowers, it'll die. Mowing it flat regularly will also kill it.

On the other hand, with a laser you could process huge areas at extreme speeds. Think 100 zaps a second.

> Think 100 zaps a second.

At very low power, not enough power to kill a plant that has lots of water in it.

Why do you assume low power? :)

While you're at it, attach it into a drone. Useful for animal herding and crowd control as well.

> Why do you assume low power? :)

Because outside of a lab, lasers with enough power to zap and destroy 100 plants per second don't actually exist?

(Not that I've done the math, but you really do need a lot of power.)

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