Sept 20 (Reuters) -Basis bids for soybeans shipped by barge to the U.S. Gulf Coast were mixed on Friday, while export premiums were steady to firm as tight loading capacity and renewed demand from China supported the market, traders said.

* Chinese importers booked several cargoes of U.S. soybeans this week, according to U.S. Department of Agriculture (USDA) data and private traders. The USDA confirmed 121,000 metric tons in sales on Friday morning, but traders said several more cargoes had traded, mostly for shipment from the Pacific Northwest.

* Nearby Gulf export premiums remain elevated due to recent weather disruptions to loading that have delayed scheduled loadings on the books further into October and November, traders said.

* Grain barge movement on the Mississippi River remained slow due to low water and restrictions on barge drafts and tow sizes.

* CIF September soy barges were bid steady at 70 cents over Chicago Board of Trade November soybean SX24 futures, while October barge bids slipped 2 cents to 72 cents over futures.

* December soybean barges traded at 75 cents over CBOT January SF25 futures, up 3 cents from bids early in the day.

* FOB soy export premiums for the first half of November, the earliest available loading slot, were up 1 cent at around 132 cents over futures, while last-half November offers were up a penny at 123 cents over futures.

* CIF corn barges loaded in September were bid 3 cents lower at 68 cents over CBOT December CZ24 futures. October barge bids fell 4 cents to 74 cents over futures.

* FOB Gulf export premiums for corn were 115 cents over futures for first-half November shipment and 112 cents over for last-half, both unchanged.

Reporting by Karl Plume in Chicago; Editing by Aurora Ellis

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