CHICAGO, Jan 31 (Reuters) - Spot basis bids for corn were down and soy bids were mixed in the U.S. Midwest on Friday amid slow farmer selling, while Chicago Board of Trade soy and corn futures came under pressure from traders booking profits ahead of the month's end.

* The corn basis fell at a Nebraska elevator and an Illinois river terminal.

* The soy basis fell at an Ohio elevator and an Indiana processor. The basis rose at an Illinois river terminal.

* Market players are also positioning ahead of the weekend, when U.S. President Donald Trump says he will impose tariffs on imports from Canada and Mexico, traders said.

* Farmer selling has petered off following a rally the previous week, and dealers said buyers have secured enough grain and oilseeds to cover their short-term needs.

* Hot, dry weather that has damaged crops in Argentina's corn and soy belts will likely keep a floor on prices in the coming week, traders said.

* Most-active CBOT corn futures Cv1 were down 5 cents to $4.85-1/4 a bushel by 10:20 a.m. CST (1620 GMT), while most-active soy futures Sv1 were up 3-1/4 cents to $10.47-3/4 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 Heather Schlitz)

((Heather.Schlitz@thomsonreuters.com;))