By Twilight Greenaway for Civil Eats.Broadcast version by Mark Moran for Iowa News Service reporting for the Solutions Journalism Network-Public News Service Collaboration Last August, Zack Smith welcomed a group of farmers, agricultural researchers, and investors to his mid-sized farm just south of the Iowa-Minnesota border for a field day. It was warm out, shorts weather, and around 35 people sat on straw bales listening as the young, fifth-generation farmer—who has gained a devoted audience through Twitter and YouTube and welcomes curious visitors to his farm every year&mdash...