Lawmakers from Iowa and other farm states will face stiff challenges from tight federal budgets, environmental activist groups and the growing clout of urban lawmakers as they try to craft a new safety net program to replace the 2014 farm bill, according to Jonathan Coppess of the University of Illinois at Urbana-Cham­p­­aign.

"Just like the last one, it’s going to be a massive political challenge to get a new farm bill done and done on time," Coppess said last week at...