Soybean futures climbed for the fourth straight day, as the combination of firm cash market prices and shrinking South American crop potential fueled advances.

The most active March contract rose to its highest level since October on continuation charts.

The uncertainty of South American production, with crops in Argentina and Brazil suffering through a severe drought in December and January, has traders questioning the region's production potential.

Fears of shrinking yields were stoked by influential private forecasters lowering production outlooks Friday, said Chad Henderson, analyst with Prime Ag Consultants in Brookfield, Wis.

Private analytical firm Informa Economics on Friday lowered its outlook for Argentina and Brazil soybean harvests. Informa, a closely watched crop forecaster, cut its estimate for Argentina's soybean crop to 46.5 million tons from previous estimate of 51 million tons, and trimmed its estimate for Brazil by 2 million from its previous estimate to 70 million tons.

Traders had anticipated smaller crop forecasts, but the estimates fell to the low end of expectations, giving a boost to traders looking for a bullish spark, Henderson said.

Analysts are still hyping up early-season dryness, despite recent improvement in crop conditions, and with soybeans relatively cheap compared to corn, traders had enough momentum to push prices to the top of recent trading ranges, Henderson added.

Firm cash market prices supported futures, as slow farmer selling tightens available supplies, and export interest picks up as importers fear prices rising if South American crops shrink.

CBOT March soybeans ended up 15 1/2 cents, or 1.3%, at $12.32 1/2 per bushel.

Corn futures ended higher, climbing in the last few minutes of trading on spillover support from soybeans and near-term supply concerns. With soybeans rallying on South America worries, traders say corn risks losing acreage in the U.S. if prices don't keep up and give farmers the incentive to plant it.

CBOT March corn ended up 1 1/2 cent to $6.44 1/2 a bushel.

U.S. wheat futures end mostly lower as worries about reduced Russian supplies dissipate. The market was pressured by signals that Russia doesn't plan export curbs as many had expected, and that world supplies remain ample regardless.

CBOT March wheat ended down 2 cents to $6.60 3/4 per bushel, KCBT March wheat closed down 5 cents to $7.12 3/4, and MGEX March wheat ended up 2 1/2 cents to $8.38 1/4.

-By Andrew Johnson Jr., Dow Jones Newswires; 312-347-4604 begin_of_the_skype_highlighting 312-347-4604 end_of_the_skype_highlighting; Andrew.johnsonjr@dowjones.com