As someone mentioned above, that's where robots come in.

grogenaut · on April 13, 2017

On gantrys? on wheels between the wheat rows? driving over the wheat on that even ground? combine sized? How much placement / spacing do they need?

pbhjpbhj · on April 13, 2017

A drone does a fly past mapping the field, then cockroach-sized robots crawl the field locating and cutting weed roots with mechanical jaws. A spike-footed walker then vacuums up the loose weeds and feeds turn to a digester that makes the fuel to run the robots ... simples!

It's all good until they get a taste for blood.