Aug 30 (Reuters) -Spot basis bids for soybeans and corn shipped by barge to the U.S. Gulf Coast turned higher on Friday, amid signs of buyer demand and as exporters watch for rain forecasts in the central U.S., traders said.

* FOB export premiums continued to firm for deferred months, particularly for soybeans, traders said.

* Exporters sold 132,000 metric tons of U.S. soybeans to China and 100,000 metric tons of soymeal to Colombia, the U.S. Department of Agriculture said in a daily reporting system.

* While export demand has picked up recently for U.S. oilseeds, Chinese buyers have also been scouting supplies from South America, two trade sources said.

* Barge traffic and towing this past week was restricted in parts of the lower Mississippi River, with river water levels falling and some closures being reported between mile markers 775 through 785, three sources told Reuters.

* Barge freight costs have continued to stay elevated on concerns of lower water levels during the harvest season, traders said. BG/US

* CIF Gulf bids for soybean barges loaded in August were up 7 cents at 72 cents over CBOT November soybean SX24 futures. September soybean barge bids were up 2 cents at 72 cents over November futures.

* FOB soybean export premiums for early September loading at the Gulf were steady at around 107 cents over November futures. Last-half September shipments were up 3 cents to about 104 cents over futures.

* CIF Gulf corn barges loaded in December traded at 81 cents over CBOT December corn CZ24 futures.

* CIF Gulf corn barges loaded in August had no bids or offers, though September corn barges were bid up 4 cents at 77 cents over December futures.

* FOB Gulf September corn export premiums were steady at about 95 cents over CBOT September corn CU24 futures, while October export premiums were steady at about 108 cents over December futures.

Reporting by P.J. Huffstutter; editing by Jonathan Oatis

For displays of CIF basis, click on the codes in brackets: U.S. CIF Gulf soybeans GRYM U.S. CIF Gulf corn GRYN U.S. CIF Gulf SRW wheat GRYO U.S. CIF Gulf HRW wheat GRYP
For displays of FOB basis, please click on the following codes in brackets: U.S. FOB Gulf corn GRZC U.S. FOB Gulf soybeans GRZD U.S. FOB Gulf SRW wheat GRZE U.S. FOB Gulf HRW wheat GRZF LINKS Corn prices page: cpurl://apps.cp./cms/?pageid=corn-cash-market
Wheat prices page: cpurl://apps.cp./cms/?pageid=wheat-cash-market
U.S. barge freight BG/US
U.S. export sales estimates USDA/EST
U.S. grain export summary GRA/U
Brazil soybean export prices SYBS
Brazil corn export prices SYBX
Argentina grain prices GRA/ARG
Russia grain prices GRA/RU