In its monthly World Ag Supply and Demand Estimates (WASDE) report Tuesday Morning, USDA left U.S. corn stocks and use unchanged and lowered global soybean production based largely on crop trouble in South America.

U.S. Grain Stocks

• Corn: 801 million bushels
• Soybeans: 250 million
• Wheat: 793 million bushels

World Production

• Brazil corn: 62.0 million metric tons
• Argetina corn: 21.5 mmt

• Marketing Talk: Report reaction
• WASDE reports support grain prices
  
• Also: Brazil slashes soybean estimates
  
• See the full WASDE report

The unchanged number for corn is still thought to be bullish, traders say, while the world carryover numbers for soybeans are seen as bullish as well. Overall, that should translate to a higher start to the trade Tuesday. Corn is seen opening 2-5 cents higher, soybeans 10-15 cents higher and wheat 5-7 cents higher, sources say.

Though the unchanged U.S. numbers aren't much to write home about, the world numbers are definitely positive for the grains, says analyst and trader Don Roose with U.S. Commodities in West Des Moines, Iowa. Moving forward, he says it's all a matter of how much attention is paid to those South American numbers, which USDA tightened Tuesday.

"Certainly the U.S. numbers are a bit on the negative side, but I think the world supply/demand tables are positive. How much weight are we going to put on those world numbers over the U.S.?" he says. "We kind of know what we have for crops here and around the world, as far as South America. At what point does South America get dialed in versus a new crop coming at us in the U.S.? That's what we have to give a chance to go higher."