Farmer Greg Willison and his son grew hemp for the first time last year near Coos Bay, Ore., and made money despite the many risks of raising a new crop. “People need to keep in mind this is something you want to approach on small acreage, maybe 5 to 10,” said Willison, who is retired and lives in New Plymouth, Idaho.Current and prospective growers of industrial hemp face many challenges in raising and marketing the controversial and high-priced new crop, which the 2018 Farm Bill authorized with the condition that states develop plans for managing it.Even producers and researchers in states such as Oregon that studied the crop under pilot programs allowed under the previous Farm Bill say there are plenty of lessons yet to be learned.