Except for a brief retreat in early October, corn, soybean and wheat prices were in a steady uptrend from June 30 through Nov. 9. December 2010 corn futures increased about 70%, whereas January 2011 soybean futures and July 2011 wheat futures increased about 50%. But the uptrend in crop prices has stalled, says University of Illinois Agricultural Economist Darrel Good.

"The fundamental reasons for the large price increases have been well chronicled. The factors include smaller-than-expected corn acreage in the U.S., declining U.S. corn yield prospects, a rapid rate of corn use for ethanol, a torrid pace of U.S. soybean exports, rising world vegetable oil demand, a significant decline in wheat production in Russia and Kazakhstan and a very poor start for the U.S. winter wheat crop," he says.

La Niña weather conditions also raised some concern about southern hemisphere crops. In addition, overall demand prospects for U.S. commodities were supported by the declining value of the U.S. dollar and rising energy prices, he says.

"Corn prices experienced the sharpest rally due to the magnitude of the decline in U.S. production prospects and expectations of a sharp drawdown in inventories of U.S. corn by the end of the 2010-2011 marketing year. The USDA currently projects those stocks at a 15-year low of 827 million bushels," Good says.

Soybean prices have been supported by the rapid pace of exports and export sales. The USDA now expects 2010-2011 marketing year U.S. soybean exports to reach 1.57 billion bushels, 4.6 percent above the record exports of a year ago, he said.

"Through the first 10 weeks of the marketing year, export inspections exceeded those of a year earlier by 25%. Shipments to China were up 49%, and China accounts for 68% of all U.S. exports to date. Unshipped export sales as of Nov. 4 were 12% larger than sales of a year ago. China accounted for 58% of those outstanding sales," he says.