GRAINS-Corn slumps to one-week low as U.S. supplies hit market

* U.S. harvest advances, set to flood market

* Wheat firms on Black Sea dry weather concerns

* Soybeans edge higher

SYDNEY, Oct 4 (Reuters) - U.S. corn fell to a one-week low on Wednesday as North America's harvest began to fill the market with supply. U.S. wheat edged higher to extend two-day gains to 1 percent as dry weather across the Black Sea stoked fears of lower production, while soybeans moved higher. The most active corn futures on the Chicago Board of Trade were down 0.2 percent to $3.48-3/4 a bushel by 0209 GMT, near the session low of $3.48-1/2 a bushel - the weakest since Sept. 27. Corn closed down 0.6 percent in the previous session. "Despite earlier concerns, the season has shaped up pretty well and the harvest is advancing at a steady rate," said Phin Ziebell, agribusiness economist at National Australia Bank. The U.S. Department of Agriculture on Monday said the corn harvest was 17 percent complete, and it rated 63 percent of the crop as good-to-excellent, an improvement from 61 percent a week earlier. Commodity brokerage INTL FCStone late on Monday raised its forecast of the U.S. corn yield to 169.2 bushels per acre, from 166.9 a month earlier. The most active soybean futures were up 0.1 percent to $9.56-1/4 a bushel, having closed down 0.2 percent on Tuesday. INTL FCStone now forecasts a U.S. soybean yield to 49.9 bpa, up from 49.8 previously. The most active wheat futures were up 0.1 percent to $4.48-1/2 a bushel, having closed up 0.9 percent on Tuesday. Analysts said wheat was drawing support from concerns that Black Sea grain production could fall as forecasts predict dry weather to persisting across Russia, Ukraine and Kazakhstan. Meanwhile Egypt's state grain buyer, the General Authority for Supply Commodities, bought 180,000 tonnes of Russian wheat in an international wheat tender.

Grains prices at 0209 GMT

Contract Last Change Pct chg Two-day chg MA 30 RSI CBOT wheat 448.50 0.50 +0.11% +0.84% 442.94 54 CBOT corn 348.75 -0.75 -0.21% -0.78% 353.19 43 CBOT soy 956.75 1.50 +0.16% -0.05% 959.23 42 CBOT rice 12.02 $0.00 +0.00% +0.17% $12.56 33 WTI crude 50.05 -$0.37 -0.73% -1.05% $49.28 41


Euro/dlr $1.177 $0.003 +0.27% +0.38% USD/AUD 0.7868 0.003 +0.43% +0.55%

Most active contracts Wheat, corn and soy US cents/bushel. Rice: USD per hundredweight RSI 14, exponential

(Reporting by Colin Packham; Editing by Kenneth Maxwell)