CHICAGO, Jan 30 (Reuters) - U.S. corn and soybean futures rallied on Tuesday, closing higher on a round of bargain buying after both commodities fell to multiyear lows, although supportive news about supply and demand was lacking, analysts noted.

Wheat followed the firm trend, bouncing after a slide to one-week lows.

Chicago Board of Trade (CBOT) March corn settled up 7-1/2 cents at $4.47-3/4 per bushel, rebounding after a dip to $4.36-1/2, the lowest on a continuous chart of the most-active contract since December 2020.

CBOT March soybeans ended up 24-1/2 cents at $12.18-3/4 a bushel, bouncing after falling to $11.87-3/4, the lowest on a continuous chart since November 2021. CBOT March wheat finished up 12 cents at $6.05-1/2 a bushel.

For the month, benchmark corn futures have fallen 5% and soybeans are down 6.1%, reflecting rising investor confidence about developing crops in Argentina and Brazil coupled with ample U.S. supplies after bumper 2023 harvests.

Commodity funds already hold sizable net short positions in all three grain markets, and traders appeared to be weighing whether prices would fall further, or if current fundamentals have been absorbed.

"A lot of us are still trying to decipher South American crop sizes," said Dan Basse, president of AgResource Company in Chicago. "Bear markets will end when we've digested all the news, and it's always a question if we have done that."

Market bulls noted that the International Monetary Fund slightly raised its forecast for global economic growth, a potentially supportive signal for commodities.

Others expected that slow demand would continue to dog the grain markets, given a U.S. corn surplus and a lack of interest in U.S. soybeans from top global buyer China.

"Today is going to get a lot of people excited about the lows being in ... But we've got (an) over 2 billion-bushel carry-over in corn. Without massive, massive sales, it's a long road to a tight balance sheet," said Ted Seifried, chief market strategist for the Zaner Group.

Condition ratings for winter wheat improved during January in Kansas, the top U.S. winter wheat producer, as drought eased in much of the Plains, although ratings declined in other states including Texas, the U.S. Department of Agriculture said on Monday. (Reporting by Julie Ingwersen in Chicago Additional reporting by Gus Trompiz in Paris and Peter Hobson in Canberra Editing by Marguerita Choy and Matthew Lewis)