kansas corn
David DeHetre via Flickr
Corn futures have fallen $0.40 a bushel, the most allowed by the Chicago Board of Trade in a single day. 
Trading in the commodity was halted after testing those lower limit bounds, and are currently priced 5.1 percent lower at $7.455 a bushel. 
Wheat quoting was also temporarily halted in afternoon trade, after prices dropped 6.2 percent to $8.5575 a bushel. 
The CBOT updates daily price limits on a daily basis, the equivalent of a circuit breaker in New York equity exchanges.
Prices of both agriculture commodities have moved violently as the drought across the U.S. aggravated the nation's crop.