It uses three high-resolution cameras to peer down at the ground below. Lit by synchronized strobe lights, an onboard computer creates a digital image of each seedling as it glides by, comparing them with all the greenery it might reasonably find in a field of rich Salinas valley farmland two hours south of San Francisco. "It puts a dot on the stem and maps around it," says Todd Rinkenberger of FarmWise, the robot's maker. "Now it knows what's plant. Everything else is a weed."

Farming robots may hold a promise of a cleaner and safer agricultural future. Potential downsides may arise from the loss of much-needed jobs to the safety of those working alongside the robots. Therefore, a process of responsible development is required. In the project called Robot Highways, multiple uses for autonomous robots made by Saga Robotics are currently demonstrated on a fruit farm in southeast England. Robots are now treating plant diseases in fields and glasshouses and will be mapping terrain, picking, packing, and providing logistical support to workers over the course of the project.

Farming robots that can move autonomously in an open field or greenhouse promise a cleaner, safer agricultural future. But there are also potential downsides, from the loss of much-needed jobs to the safety of those working alongside the robots. To ensure that the use of autonomous robots on farms creates more benefits than losses, a process of responsible development is required. Society as a whole needs to be involved in setting the trajectories for future farming. We are part of a project called Robot Highways, which is currently demonstrating multiple uses for autonomous robots made by Saga Robotics on a fruit farm in south-east England.

Last week a startup based at Plymouth University unveiled the world's first raspberry-picking robot. The machine can pick about 25,000 berries a day, which is 10,000 more than a human during an eight-hour shift. Raspberries are particularly challenging for machines to harvest because the robots have to identify ripe fruit and handle the soft berries without damaging them. The firm intends to lease the robots to farmers at a rate that would undercut the cost of employing human fruit pickers. Last month farming startup Iron Ox began selling salad partly farmed by robots at a store in California.

It was a hot February morning at Wish Farms, a large strawberry-growing operation outside Plant City, Florida. Gary Wishnatzki, the proprietor, met me at one of the farm offices. In the high season, Wish Farms picks, chills, and ships some twenty million berries--all handpicked by a seasonal workforce of six hundred and fifty farm laborers. Wishnatzki is a genial sixty-three-year-old third-generation berry man, who wears a white goatee and speaks softly, with a Southern drawl. His grandfather Harris Wishnatzki was a penniless Russian immigrant who started out peddling fruits and vegetables from a pushcart in New York's Washington Street Market in 1904.

In a quiet corner of rural Hampshire, a robot called Rachel is pootling around an overgrown field. With bright orange casing and a smartphone clipped to her back end, she looks like a cross between an expensive toy and the kind of rover used on space missions. Up close, she has four USB ports, a disc-like GPS receiver, and the nuts and bolts of a system called Lidar, which enables her to orient herself using laser beams. She cost around £2,000 to make. Every three seconds, Rachel takes a closeup photograph of the plants and soil around her, which will build into a forensic map of the field and the wider farm beyond. After 20 minutes or so of this, she is momentarily disturbed by two of the farm's dogs, unsure what to make of her.

The US is facing an agricultural worker shortage, along with aging farm owners, at the same time it juggles demand in food from a global population boom. If we're being blunt, those elements added together would mean farmers and production are straight screwed. Luckily, some engineers and researchers are creating robots that are already beginning to ease the load. Blue River Technology in Sunnyvale, California is testing "See and Spray"-- machine learning and AI software inside a robotic tractor attachment that aims to change the chemical game. The program can recognize the difference between crops and weeds, then sprays herbicide only on the unwanted plant.

The global market for agricultural robots will explode to 73.9 billion by 2024, up from 3.0 billion 2015, according to Tractica, a market intelligence firm. It forecast driverless tractors would generate the most revenue -- 30.7 billion by 2024 -- with agricultural drones clocking up the most unit shipments. Drones with specialized cameras are increasingly used for monitoring crops and livestock. A newer use is crop spraying -- which can be dangerous for laborers due to the chemicals used -- although this is expensive and currently only used by large farms. "As technology continues to evolve, farmers and ranchers will reassess in order to make the most practical decisions for their bottom line," the president of the U.S. National Farmers Union, Roger Johnson, told CNBC on Wednesday. Follow CNBC International on Twitter and Facebook.