CHICAGO, Feb 19 (Reuters) - Spot basis bids for soybeans delivered to river elevators and processing facilities around the U.S. Midwest were steady to firm on Wednesday, while bids at interior elevators were mostly unchanged, dealers said.

* Spot corn basis bids were flat at interior and river elevators, steady to firm at ethanol plants and mixed at other processors.

* A large corn processor in Decatur, Illinois, raised its spot basis bid by 3 cents on Wednesday, while the spot bid at a Cedar Rapids, Iowa, corn plant fell 2 cents.

* Spot corn bids at ethanol plants were steady to up 5 cents a bushel.

* Farmer sales of corn accelerated this week as Chicago Board of Trade futures values rose above $5 a bushel for the first time in 16 months. Demand for corn remained strong.

* Soybean basis values rose at some processing plants as the U.S. crushing pace remained brisk despite thinning margins and a modest drop in crushing efficiency due to frigid weather. The National Oilseed Processors Association said the January crush was the second highest on record following a recent expansion of U.S. processing capacity.

* CBOT March corn futures were down 4-3/4 cents at $4.97-1/4 a bushel near midday on Wednesday. CBOT March soybeans SH25 were down 5 cents at $10.33-1/2 a bushel.

Basis values are quoted against CBOT futures in cts/bu:

NOTE: 0 = Option price, UNC = Unchanged, UNQ = Unquoted

NC = Not comparable, DP = Delayed price, N/A = Not available,

F = January, H = March, K = May, N = JulyQ = August, U = September, X = November, Z = December

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LINKS: 0#USCSHGRN-PM

For U.S. forward basis spreadsheets, please click:

CORN/BASIS, SOYA/BASIS, WHEAT/BASIS, MILO/BASIS

- CBOT corn report COR/

- CBOT soybean report SOY/C

- CBOT wheat report WHE/C

- U.S. grain barge freight values BG/US

- U.S. Midwest cash grain PM GRA/PM

- U.S. CIF/FOB Gulf Grain GRA/F

(Reporting by Karl Plume; Editing by Kirsten Donovan)

((karl.plume@thomsonreuters.com; +1 313 484 5285))