The depreciation of the U.S. dollar since 2002 has helped increase the real (adjusted for inflation) value of U.S. agricultural exports to record levels. A relatively low dollar means that U.S. exports are less expensive in foreign currency terms and helps make U.S. agricultural exports competitive in foreign markets. The recent depreciation of the euro implies some competition for agricultural export markets from European exporters, but the overall expectation is that the dollar is likely to stay competitive relative to most other currencies in the world. This chart is from September 2010.
source: usda