CHICAGO, April 4 (Reuters) - Spot basis bids for corn were steady to firmer in the U.S. Midwest on Friday, reflecting grain demand from processors and elevators amid a slow pace of corn sales by farmers, dealers said.

* The corn basis firmed by 2 cents a bushel at a Union City, Indiana, ethanol plant.

* Soybean basis bids held steady even as Chicago Board of Trade soybean futures SK25 fell about 3% and slipped below $10 a bushel.

* CBOT futures tumbled after top soy importer China said it would impose additional tariffs of 34% on all American goods in retaliation against duties announced by President Donald Trump. GRA/

* Rains continued to stall early corn planting in the eastern Midwest. The National Weather Service posted flood watches and warnings on Friday from Arkansas and western Tennessee through the Ohio River Valley.

* As of 12:28 p.m. CDT (1728 GMT), CBOT May soybeans SK25 were down 33 cents at $9.78-1/2 per bushel. May corn CK25 was up 3 cents at $4.60-1/2 a bushel while May soft red winter wheat WK25 was down 7-1/4 cents at $5.28-3/4 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 Julie Ingwersen; editing by Diane Craft)

((Julie.ingwersen@thomsonreuters.com; 1-313-484-5283; Reuters Messaging: julie.ingwersen.thomsonreuters.com@reuters.net))