For most of the last century, U.S. corn accounted for between 50 and 75 percent of world corn exports, but over the last decade the United States has lost its dominance in world corn markets.

The U.S. ethanol program provided underlying support for corn prices after 2005 and, together with rising global feed demand and policies in some foreign countries, encouraged expansion in foreign corn production, with Brazil and Ukraine notably successful.

In 2012/13 (October/September), with several years of below trend U.S. yields compounded by severe drought, foreign corn has become increasingly competitive in world markets.

U.S. corn export market share is forecast to fall to less than 20 percent in 2012/13.

With record U.S. corn production projected for 2013/14, U.S. export share is expected to increase and the United States is expected to return as the largest exporter.

But the U.S. market share is forecast to remain well below 50 percent, while Brazil, Ukraine, and Argentina are each forecast to account for 15 to 20 percent of world corn trade.

The chart is adapted from the Feed Grains Chart Gallery.