GRAINS-Wheat eases but set for weekly rise on U.S. drought

* Wheat headed for fourth straight weekly gain on dry weather

* Corn up for ninth week in 10; soybeans firm

* Investors eye USDA quarterly stocks, plantings report on Monday

(Updates prices, adds analyst comments, changes byline, adds dateline) CHICAGO, March 28 (Reuters) - U.S. wheat futures fell 2.2 percent on Friday as investors awaited key U.S. planting and stocks data but stayed on course for a small weekly rise as the market worried about dry weather in the U.S. Plains. Corn and soybeans inched higher in subdued trading in the run-up to Monday's spring planting and quarterly stocks estimates from the U.S. Department of Agriculture, a data release that often generates sharp price movements. Wheat futures were headed for their biggest daily drop in 10 days, but rallies early this week had prices on track for their fourth straight weekly gain. Investors made bullish bets on concerns that drought will hurt wheat crops in major producing states like Kansas, Oklahoma and Texas, adding to recent support from tensions between major grain exporters Russia and Ukraine. But forecasts for some rain in parts of the U.S. grain belt and the prospect of large global harvests in 2014 have acted as a brake on wheat prices ahead of Monday's USDA numbers. "There are more-than-adequate supplies of old-crop coarse grains, and we see the likelihood of another large global 2014 wheat and corn harvest," David Sheppard, managing director of UK merchant Gleadell, said in a note. "However, as we have seen over the past few weeks, we should never underestimate the power of politics and the impact of perceived or real weather events." Wheat for delivery in May on the Chicago Board of Trade was down 16-1/2 cents at $6.94 a bushel at 11:20 a.m. CDT (1620 GMT). Traders were also unwinding wheat and corn spreads, said analyst Terry Linn of the Linn Group brokerage in Chicago. "Some technical signals suggest we may have a top in the spread," Linn said. "Absolutely, that spread is a factor. "The wheat market hasn't broken down; we are just consolidating in a range. We probably won't break down in front of the (USDA) number, but we have a shot across the bow." CBOT May corn was up 1 cent at $4.93 a bushel after hitting a nearly three-week high of $4.96-1/4 on strong U.S. exports. Corn is up 3 percent this week, its ninth increase in 10 weeks. U.S. corn sales last week stood at 1.4 million tonnes, well above analysts' expectations that ranged from 525,000 to 725,000 tonnes, a USDA report showed. Soybeans were up 3 cents at $14.39-1/2 per bushel and on track for a weekly gain of 2 percent. U.S. soybean export sales last week reached only 11,900 tonnes, near the marketing-year low hit in mid-February and suggesting tight U.S. stocks may be curbing demand after brisk demand so far this season. Analysts expect Monday's USDA report to show U.S. soybean stocks by March 1 were 989 million bushels, which would be the smallest since 2004. U.S. corn stockpiles are seen at 7.099 billion bushels, the biggest since 2010, and wheat stocks at a five-year low of 1.042 billion bushels.

Prices at 11:20 a.m. CDT (1620 GMT)

LAST NET PCT YTD CHG CHG CHG CBOT corn 493.00 1.00 0.2% 16.8% CBOT soy 1439.50 3.00 0.2% 9.7% CBOT meal 470.10 -0.40 -0.1% 7.4% CBOT soyoil 40.56 0.13 0.3% 4.5% CBOT wheat 694.00 -16.50 -2.3% 14.7% CBOT rice 1548.50 1.50 0.1% -0.2% EU wheat 210.25 -1.25 -0.6% 0.6% US crude 101.67 0.39 0.4% 3.3% Dow Jones 16,390 126 0.8% -1.1% Gold 1290.60 -.04 0.0% 7.1% Euro/dollar 1.3750 0.0011 0.1% 0.7% Dollar Index 80.2140 0.1030 0.1% 0.2% Baltic Freight 1373 -39 -2.8% -39.7%

(Additional reporting by Julie Ingwersen in Chicago, Gus Trompiz in Paris and Manolo Serapio Jr in Singapore; Editing by Clarence Fernandez, Lisa Von Ahn and Keiron Henderson)