With low commodity prices persisting and agricultural input costs remaining stubbornly high, financial stress is starting to germinate in farm country, according to agricultural banker surveys conducted recently by the Federal Reserve banks in Chicago and Kansas City.

Demand for operating loans and loan renewals from farmers has risen sharply, and loan repayment rates are down, according to bankers in the two surveys that covered large swaths of the Midwest and the Plains states.

In addition, more ag bankers are requiring that borrowers supply larger amounts of collateral to secure operating...