Exports and the strength of the U.S. dollar will exert significant influence over the direction of crop and livestock prices this year, economists said last week at the American Farm Bureau Federation annual convention in Phoenix.

A slowdown in China’s economic growth will temper demand for U.S. corn and soybeans, said Pat Westhoff, an economist at the University of Missouri’s Food and Agricultural Policy Research In­­stitute. Ethanol prod­uction, the other major growth market for corn during the past two decades, has also plateaued.

"It’s hard to find a replacement of another China or another ethanol," said Westhoff.

U.S. commodities are also getting more expensive for many...