CHICAGO, Jan 30 (Reuters) - Spot basis bids for soybeans were flat or fell in the U.S. Midwest on Thursday, as futures retreated from six-month highs hit the previous day. Corn bids were mixed at elevators.

* The soy basis fell 4 cents at an elevator in Ohio and 2 cents at an Illinois river terminal.

* Corn basis bids rose 1 cent at an elevator in Ohio and fell down 4 cents at another in Nebraska.

* U.S. corn and soybean futures fell after rising to multi-month highs the previous day on an improving forecast in Argentina, a major producer of both crops.

* Most-active CBOT corn futures Cv1 were down 5-3/4 cents at $4.91-1/4 a bushel by 10:09 a.m. CST (1609 GMT), while most-active soy futures Sv1 were down 16-1/4 cents to $10.44-1/4 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 Renee Hickman; editing by Barbara Lewis)

((renee.hickman@thomsonreuters.com))