Robot farmers are coming to a field near you

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.