On the Chicago Mercantile Exchange, corn futures for December delivery fell 1.4% on Friday to settle the week at USD4.5888 a bushel. The December contract settled 1.3% lower on Thursday at USD4.6620 a bushel.
For the week, the December corn contract lost 2%, the second consecutive weekly decline.
The USDA said Thursday the U.S. corn crop will total 13.84 billion bushels in the 2013 marketing season, up 0.6% from its August forecast and the largest crop on record.
Meanwhile, soybeans for November delivery declined 0.95% on Friday to settle the week at USD13.8188 a bushel by close of trade. The November contract jumped 2.8% on Thursday to settle at USD13.9600 a bushel, the strongest level since September 3.
Prices of the oilseed declined Friday as investors cashed out of the market to lock in gains from Thursday’s 2.8% rally.
Despite Friday’s losses, the November soy contract rose 0.9% on the week, the sixth consecutive weekly advance, as lingering warm and dry weather fuelled concerns over crop conditions.
The USDA lowered its forecast for the U.S. soybean crop on Thursday to 3.149 billion bushels, down 3% from its estimate in August.
Soybean stockpiles will total 150 million bushels the end of the current crop year on August 31, 2014, below analysts' expectations for 161 million bushels.
Elsewhere on the Chicago Board of Trade, wheat for December delivery tumbled 1.8% on Friday to settle the week at USD6.4050 a bushel. CBOT December wheat prices rose 0.8% on Thursday to settle at USD6.5300 a bushel.
The December wheat contract ended the week with a 1.1% decline, the second consecutive weekly loss.
The USDA raised its estimate for global wheat production to a record 708.89 million metric tons, up 0.5 percent from last month.
In the week ahead, corn and soybean traders will continue to pay close attention to weather forecasts for grain-growing regions in the U.S. Midwest, while wheat traders will monitor temperatures in the Great Plains-region.
Corn is the biggest U.S. crop, followed by soybeans, government figures show. Wheat was fourth, behind hay.