Actually the limits are 20 c for Corn, 30 c for Wheat and 50 c for Soybeans.
All traders should go straight to source itself....at the CBOT... to verify, and not rely upon anecotal reports or secondhand news.
Corn: 20/c
CBOT - Corn Quotes Open Auction
Wheat: 30/c
CBOT - Wheat Quotes Open Auction
Soybeans: 50/c
CBOT - Soybeans Quotes Open Auction
Look for the section that says "Daily Price Limit".
Good trading, folks!