Could AI robots with lasers make herbicides -- and farm workers -- obsolete?

The smell of burnt vegetation wafted through a lettuce field here one recent summer morning as nearly 200 farmers, academics and engineers gathered to witness the future of automated agriculture. Thirteen hulking machines with names like "Weed Spider" and "Mantis" crawled through rows of romaine. One used artificial intelligence cameras to scan the crops and spray them with herbicides. Yet another deployed robotic arms to cultivate and pick through the foliage. "It's a hurdle for people to get over, but the reality is, the numbers don't lie," said Tim Mahoney, a field representative for Carbon Robotics, a Seattle-based company that created one of the machines on display -- a 9,500-pound apparatus known as the LaserWeeder.