PRIMROSE, Wis. (AP) — The farmland along Sun Valley Parkway east of Paoli is still fertile soil for corn, soybeans, alfalfa and other traditional crops.

But a 120-acre farm established in the 1800s along a rail line that is now the Badger State Trail is trying to make a year-round business out of lettuce, herbs and micro greens, thanks to a greenhouse, tanks of tilapia and the entrepreneurial drive of its owners and small staff.

Clean Fresh Foods is the creation of Mike and Dagny Knight, who are skipping the dirt. Instead, their aquaponics farm uses tanks and troughs of well water in an attemp...