Investing.com - U.S. grain futures ended Friday's session sharply lower, with soybean prices sinking to a four-week low amid speculation this year's harvest will be larger-than-expected.
On the Chicago Mercantile Exchange, soybeans for November delivery tumbled 1.8% on Friday to settle the week at USD13.1520 a bushel by close of trade.
Prices of the oilseed fell by as much as 2.1% earlier in the day to hit a session low of USD13.1160 a bushel, the weakest level since August 21. The November contract shed 0.6% on Thursday to settle at USD13.3940 a bushel.
On the week, prices of the oilseed lost 4.8%, its first weekly decline in seven weeks and the biggest drop since May 2012.
Soybean prices rallied throughout most of August as warm and dry weather in the U.S. Midwest fuelled concerns over crop conditions.
However, heavy recent rainfall and favorable weather conditions in major soy-growing states in the U.S. stocked speculation that yield potential may be larger than analysts had expected.
On Friday, industry research group Informa Economics raised its estimate of U.S. soybean production in the current marketing season to 3.224 billion bushels, above the U.S. Department of Agriculture's most-recent forecast for 3.149 billion.
Informa also projected that U.S. soybean plantings for 2014 would reach 83.6 million acres, 8% above the 2009 record of 77.5 million acres.
Meanwhile, corn futures for December delivery plunged 1.85% on Friday to settle the week at USD4.5100 a bushel.
Corn prices fell by as much as 1.95% earlier in the session to hit a daily low of USD4.5040 a bushel, the weakest level since August 13. The December contract settled 0.7% higher on Thursday at USD4.5940 a bushel.
For the week, the December corn contract lost 1.4%, the third consecutive weekly decline.
Corn prices have been on a downward trend in recent weeks as market players continued to monitor improving crop conditions in the U.S. Midwest.
Informa Economics on Friday raised its estimate for the 2013 corn crop to 13.889 billion bushels, above the USDA's forecast of 13.843 billion, which would be the largest crop on record.
Elsewhere on the Chicago Board of Trade, wheat for December delivery slumped 1.65% on Friday to settle the week at USD6.4620 a bushel.
CBOT December wheat prices rallied 1.6% on Thursday to settle at USD6.570 a bushel, the strongest since September 3.
The December wheat contract ended the week with a 0.9% gain, the first weekly advance in three weeks.
News of favorable planting weather in the U.S. Great Plains region weighed on wheat prices.
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.
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