Grain markets are roiling from the political crisis in Ukraine, but it appears unlikely there will be major global supply shocks, according to a Reuters report. Wheat already has been harvested and shipped, and global stockpiles of corn can substitute for Ukraine maize.

"The Black Sea region can easily expand or contract at the drop of a dime when it comes to production and exportable supply," said Terry Reilly, senior commodities analyst with Futures International.

The Ukrainian wheat crop of 2013-14 is past the stage of being affected by the crisis because it is already harvested and the export portion shipped. Ukraine is the world's sixth-largest wheat exporter, and ships much of its wheat to Egypt and other countries around the Middle East and North Africa.

Record corn stocks in the U.S. means there is plenty of corn to ship to meet demand if Ukraine shipments are cut off, traders and analysts said.


"If there is any major disruption in corn exports, the market will be comfortable to quickly adapt and turn to U.S. supplies or even South America. There is a lot of wheat that could potentially come on line as well, especially from Canada, India, maybe Australia, and of course the U.S.," Reilly said.

Major grain companies say they are monitoring developments in the Black Sea region, and that shipments have not been slowed so far. However, shippers in the region have begun building risk premiums into freight costs in and out of the region.

As the Ukrainian and Russian currencies continue to fall, farmers see little incentive to unload their grain. And, if economic sanctions further weaken the Russian ruble, grain available for export from the region could tighten further, according to Kevin Van Trump, chief executive of Farm Direction, a consultancy based in Raymore, Missouri.

"The producers might get more tight-fisted with the bushels they're producing and hunker down," Van Trump said. "They're just not going to sell to the exporter."