GRAINS-U.S. corn drops on profit-taking; soy, wheat unchanged

* Corn falls half a pct on profit taking after recent gains

* Wheat, soy little changed ahead of USDA stocks report

* Wheat falls for 6 quarters in row, soy down 25 pct in Q3 (Adds details, quotes)

SINGAPORE, Sept 30 - U.S. corn futures slipped half a percent on Wednesday as traders booked profits after recent gains and a threat from cold weather damaging this year's late maturing U.S. crop receded.

Wheat, which is on track for six straight quarters of losses, was little changed ahead of a U.S. Department of Agriculture report on grain stocks and wheat harvest data, while soybeans were nearly flat in thin trade.

"It's a little bit of profit-taking in corn after some strength in the past few days," said Brett Cooper, a trader with MF Global Australia.

"The temperatures were not cold enough to cause any serious damage, I think that story is past. It is also squaring up ahead of the USDA report."

Corn rose five percent last week, registering its best performance in eight weeks, as weather forecasts called a crop-killing freeze.

U.S. farmers are in the early stages of harvesting this year's big corn crop and soybean crop that is likely to set a record. The harvest pace is well behind average because of the late development of both crops this year.

Talk of a frost, which can harm crops that are not mature, continues to surface and move the market. For a factbox on the impact of frost on U.S. crop, please see

Soy -- which has lost a quarter of its value in the third quarter compared with gains of nearly 30 percent at the end of June -- is under pressure from the record crop and investors are expecting Chinese demand to boost prices.

U.S. soybean prices have held strong through much of this year because of strong buying by China after South America's soy crop suffered big losses from an unprecedented drought.

South American farmers are gearing up to plant the 2010 crop and the soybean acreage could be large.

Chicago Board of Trade December corn futures fell 0.4 percent to $3.39-½ a bushel by 0356 GMT, while November soybeans gained ¾ cent to $9.17-¾ a bushel.

The market noted China's purchases of several thousand tonnes of Thai corn in recent weeks, even though traders said the country was unlikely to become a major importer soon, because of weakening domestic prices.

Wheat has lost more than 12 percent in the third quarter on rising global supplies for a second straight year and the market expects the U.S. government will forecast a larger 2009 U.S. wheat crop in its September report due at 1230 GMT.

A global wheat supply glut was highlighted by Australia, the world's fourth largest exporter, where September rains have ensured the wheat crop will meet forecasts of about 22 million tonnes, the biggest in four years.

CBOT wheat for December delivery fell ¾ cent to $4.46-¾ a bushel.

PRICES AT 0356 GMT Contract Last Change Pct chg Day ago pct MA 30 RSI CBOT wheat 446.75 -0.75 -0.17% -1.97% 456.95 43 CBOT corn 339.50 -1.50 -0.44% +0.22% 322.26 57 CBOT soy 917.75 0.75 +0.08% -0.19% 985.69 36 CBOT rice $13.39 $0.08 +0.60% +1.36% $13.39 51 WTI crude $67.05 $0.34 +0.51% +0.31%

$70.24 43 Currencies

Euro/dlr $1.462 -$0.011 +0.00% +0.00% USD/AUD 0.879 0.009 +0.00% +0.00% Front month contracts Wheat, corn and soy US cents/bushel. Rice: USD per hundredweight