GRAINS-Soybeans rise on U.S. harvest rain and Brazil planting risks

* Rains seen slowing U.S. harvest,

* Dryness in Brazil among risks to S. America planting

* Corn also firms slightly, wheat stays weak

* Good U.S. yields cap corn, soy

(Updates with European trading, changes byline/dateline) PARIS/SINGAPORE, Oct 5 (Reuters) - Chicago soybean futures rose for a second session on Thursday as rains were expected to slow the U.S. harvest while dry conditions in Brazil also kept attention on weather risks to soybean planting in South America. Corn also edged higher as rain delays to harvesting were also forecast in parts of the U.S. Midwest, though expectations for good yields were curbing corn and soy markets. Wheat dipped slightly, giving up earlier marginal gains to add to Wednesday's 1.3 percent decline. The cereal remained under pressure from beneficial rains for dry U.S. wheat belts and stiff export competition from Russian wheat. The Chicago Board of Trade's (CBOT) most-active soybean contract was up 0.4 percent at $9.62-1/4 a bushel by 1134 GMT, extending similar gains the previous day. Corn rose 0.4 percent to $3.49-3/4 a bushel, while wheat edged 0.2 percent down to $4.41-1/4 a bushel. "The U.S. soybean harvest is being delayed as rains seem to be an issue," said Phin Ziebell, agribusiness economist at National Australia Bank. "There are some problems with Brazilian planting, but that is a little bit speculative at this stage." Brazilian oilseeds industry group Abiove estimated the nation's soybean output at 108.5 million tonnes in the 2017/18 season, down from a record 113.8 million tonnes in the previous crop cycle. The potential for a La Nina weather pattern in the coming months, which can cause dry conditions in Argentina, has added to uncertainty over the South American growing season. However, strong expected yields for U.S. soybean and corn crops could keep a lid on prices as the harvest progresses. "U.S. corn and soybean yields continue to rise as benign end-of-season conditions boost late grain and pod fill," Thomson Reuters Agriculture Research analysts said in a note. Soybean prices have also been underpinned by brisk demand from China in recent weeks, shipments could be slowed by a Chinese national holiday this week and reports that suppliers a struggling to find high-quality U.S. beans after hurricane damage. Grain markets will get a fresh indication of export demand from weekly U.S. export sales data at 1230 GMT. Wheat prices remained capped by export competition created by a record Russian harvest this year, underscored by Egypt's latest purchase of Russian wheat on Tuesday. Commodity funds were net sellers of CBOT corn, wheat and soymeal futures contracts on Wednesday and net buyers of soybeans and soyoil, traders said.

Prices at 1134 GMT

Last Change Pct End Ytd Pct Move 2016 Move CBOT wheat 441.25 -0.75 -0.17 408.00 8.15 CBOT corn 349.75 1.50 0.43 352.00 -0.64 CBOT soy 962.25 4.00 0.42 1004.00 -4.16 Paris wheat Dec 166.00 0.00 0.00 175.00 -5.14 Paris maize Nov 155.00 0.00 0.00 170.00 -8.82 Paris rape Nov 368.50 0.50 0.14 383.25 -3.85 WTI crude oil 50.11 0.13 0.26 53.72 -6.72 Euro/dlr 1.17 0.00 -0.11

Most active contracts - Wheat, corn and soy US cents/bushel, Paris futures in euros per tonne

(Reporting by Naveen Thukral in Singapore and Gus Trompiz Paris; Editing by Christian Schmollinger and David Goodman)